// SPDX-License-Identifier: LGPL-2.1
/*
 *
 *   Copyright (C) International Business Machines  Corp., 2002,2011
 *   Author(s): Steve French (sfrench@us.ibm.com)
 *
 */
#include <linux/fs.h>
#include <linux/net.h>
#include <linux/string.h>
#include <linux/sched/mm.h>
#include <linux/sched/signal.h>
#include <linux/list.h>
#include <linux/wait.h>
#include <linux/slab.h>
#include <linux/pagemap.h>
#include <linux/ctype.h>
#include <linux/utsname.h>
#include <linux/mempool.h>
#include <linux/delay.h>
#include <linux/completion.h>
#include <linux/kthread.h>
#include <linux/pagevec.h>
#include <linux/freezer.h>
#include <linux/namei.h>
#include <linux/uuid.h>
#include <linux/uaccess.h>
#include <asm/processor.h>
#include <linux/inet.h>
#include <linux/module.h>
#include <keys/user-type.h>
#include <net/ipv6.h>
#include <linux/parser.h>
#include <linux/bvec.h>
#include "cifsglob.h"
#include "cifsproto.h"
#include "cifs_unicode.h"
#include "cifs_debug.h"
#include "cifs_fs_sb.h"
#include "ntlmssp.h"
#include "nterr.h"
#include "rfc1002pdu.h"
#include "fscache.h"
#include "smb2proto.h"
#include "smbdirect.h"
#include "dns_resolve.h"
#ifdef CONFIG_CIFS_DFS_UPCALL
#include "dfs.h"
#include "dfs_cache.h"
#endif
#include "fs_context.h"
#include "cifs_swn.h"

/* FIXME: should these be tunable? */
#define TLINK_ERROR_EXPIRE      (1 * HZ)
#define TLINK_IDLE_EXPIRE       (600 * HZ)

/* Drop the connection to not overload the server */
#define MAX_STATUS_IO_TIMEOUT   5

static int ip_connect(struct TCP_Server_Info *server);
static int generic_ip_connect(struct TCP_Server_Info *server);
static void tlink_rb_insert(struct rb_root *root, struct tcon_link *new_tlink);
static void cifs_prune_tlinks(struct work_struct *work);

static struct mchan_mount *mchan_mount_alloc(struct cifs_ses *ses);
static void mchan_mount_free(struct mchan_mount *mchan_mount);
static void mchan_mount_work_fn(struct work_struct *work);

/*
 * Resolve hostname and set ip addr in tcp ses. Useful for hostnames that may
 * get their ip addresses changed at some point.
 *
 * This should be called with server->srv_mutex held.
 */
static int reconn_set_ipaddr_from_hostname(struct TCP_Server_Info *server)
{
        struct sockaddr_storage ss;
        int rc;

        if (!server->hostname)
                return -EINVAL;

        /* if server hostname isn't populated, there's nothing to do here */
        if (server->hostname[0] == '\0')
                return 0;

        spin_lock(&server->srv_lock);
        ss = server->dstaddr;
        spin_unlock(&server->srv_lock);

        rc = dns_resolve_name(server->dns_dom, server->hostname,
                              strlen(server->hostname),
                              (struct sockaddr *)&ss);
        if (!rc) {
                spin_lock(&server->srv_lock);
                memcpy(&server->dstaddr, &ss, sizeof(server->dstaddr));
                spin_unlock(&server->srv_lock);
        }
        return rc;
}

void smb2_query_server_interfaces(struct work_struct *work)
{
        int rc;
        int xid;
        struct cifs_tcon *tcon = container_of(work,
                                        struct cifs_tcon,
                                        query_interfaces.work);
        struct TCP_Server_Info *server = tcon->ses->server;

        /*
         * query server network interfaces, in case they change
         */
        if (!server->ops->query_server_interfaces)
                return;

        xid = get_xid();
        rc = server->ops->query_server_interfaces(xid, tcon, false);
        free_xid(xid);

        if (rc)
                cifs_dbg(FYI, "%s: failed to query server interfaces: %d\n",
                                __func__, rc);

        queue_delayed_work(cifsiod_wq, &tcon->query_interfaces,
                           (SMB_INTERFACE_POLL_INTERVAL * HZ));
}

#define set_need_reco(server) \
do { \
        spin_lock(&server->srv_lock); \
        if (server->tcpStatus != CifsExiting) \
                server->tcpStatus = CifsNeedReconnect; \
        spin_unlock(&server->srv_lock); \
} while (0)

/*
 * Update the tcpStatus for the server.
 * This is used to signal the cifsd thread to call cifs_reconnect
 * ONLY cifsd thread should call cifs_reconnect. For any other
 * thread, use this function
 *
 * @server: the tcp ses for which reconnect is needed
 * @all_channels: if this needs to be done for all channels
 */
void
cifs_signal_cifsd_for_reconnect(struct TCP_Server_Info *server,
                                bool all_channels)
{
        struct TCP_Server_Info *nserver;
        struct cifs_ses *ses;
        LIST_HEAD(reco);
        int i;

        /* if we need to signal just this channel */
        if (!all_channels) {
                set_need_reco(server);
                return;
        }

        if (SERVER_IS_CHAN(server))
                server = server->primary_server;
        scoped_guard(spinlock, &cifs_tcp_ses_lock) {
                set_need_reco(server);
                list_for_each_entry(ses, &server->smb_ses_list, smb_ses_list) {
                        spin_lock(&ses->ses_lock);
                        if (ses->ses_status == SES_EXITING) {
                                spin_unlock(&ses->ses_lock);
                                continue;
                        }
                        spin_lock(&ses->chan_lock);
                        for (i = 1; i < ses->chan_count; i++) {
                                nserver = ses->chans[i].server;
                                if (!nserver)
                                        continue;
                                nserver->srv_count++;
                                list_add(&nserver->rlist, &reco);
                        }
                        spin_unlock(&ses->chan_lock);
                        spin_unlock(&ses->ses_lock);
                }
        }

        list_for_each_entry_safe(server, nserver, &reco, rlist) {
                list_del_init(&server->rlist);
                set_need_reco(server);
                cifs_put_tcp_session(server, 0);
        }
}

/*
 * Mark all sessions and tcons for reconnect.
 * IMPORTANT: make sure that this gets called only from
 * cifsd thread. For any other thread, use
 * cifs_signal_cifsd_for_reconnect
 *
 * @server: the tcp ses for which reconnect is needed
 * @server needs to be previously set to CifsNeedReconnect.
 * @mark_smb_session: whether even sessions need to be marked
 */
void
cifs_mark_tcp_ses_conns_for_reconnect(struct TCP_Server_Info *server,
                                      bool mark_smb_session)
{
        struct TCP_Server_Info *pserver;
        struct cifs_ses *ses, *nses;
        struct cifs_tcon *tcon;

        /*
         * before reconnecting the tcp session, mark the smb session (uid) and the tid bad so they
         * are not used until reconnected.
         */
        cifs_dbg(FYI, "%s: marking necessary sessions and tcons for reconnect\n", __func__);

        /* If server is a channel, select the primary channel */
        pserver = SERVER_IS_CHAN(server) ? server->primary_server : server;

        /*
         * if the server has been marked for termination, there is a
         * chance that the remaining channels all need reconnect. To be
         * on the safer side, mark the session and trees for reconnect
         * for this scenario. This might cause a few redundant session
         * setup and tree connect requests, but it is better than not doing
         * a tree connect when needed, and all following requests failing
         */
        if (server->terminate) {
                mark_smb_session = true;
                server = pserver;
        }

        spin_lock(&cifs_tcp_ses_lock);
        list_for_each_entry_safe(ses, nses, &pserver->smb_ses_list, smb_ses_list) {
                spin_lock(&ses->ses_lock);
                if (ses->ses_status == SES_EXITING) {
                        spin_unlock(&ses->ses_lock);
                        continue;
                }
                spin_unlock(&ses->ses_lock);

                spin_lock(&ses->chan_lock);
                if (cifs_ses_get_chan_index(ses, server) ==
                    CIFS_INVAL_CHAN_INDEX) {
                        spin_unlock(&ses->chan_lock);
                        continue;
                }

                if (!cifs_chan_is_iface_active(ses, server)) {
                        spin_unlock(&ses->chan_lock);
                        cifs_chan_update_iface(ses, server);
                        spin_lock(&ses->chan_lock);
                }

                if (!mark_smb_session && cifs_chan_needs_reconnect(ses, server)) {
                        spin_unlock(&ses->chan_lock);
                        continue;
                }

                if (mark_smb_session)
                        CIFS_SET_ALL_CHANS_NEED_RECONNECT(ses);
                else
                        cifs_chan_set_need_reconnect(ses, server);

                cifs_dbg(FYI, "%s: channel connect bitmap: 0x%lx\n",
                         __func__, ses->chans_need_reconnect);

                /* If all channels need reconnect, then tcon needs reconnect */
                if (!mark_smb_session && !CIFS_ALL_CHANS_NEED_RECONNECT(ses)) {
                        spin_unlock(&ses->chan_lock);
                        continue;
                }
                spin_unlock(&ses->chan_lock);

                spin_lock(&ses->ses_lock);
                ses->ses_status = SES_NEED_RECON;
                spin_unlock(&ses->ses_lock);

                list_for_each_entry(tcon, &ses->tcon_list, tcon_list) {
                        tcon->need_reconnect = true;
                        spin_lock(&tcon->tc_lock);
                        tcon->status = TID_NEED_RECON;
                        spin_unlock(&tcon->tc_lock);

                        cancel_delayed_work(&tcon->query_interfaces);
                }
                if (ses->tcon_ipc) {
                        ses->tcon_ipc->need_reconnect = true;
                        spin_lock(&ses->tcon_ipc->tc_lock);
                        ses->tcon_ipc->status = TID_NEED_RECON;
                        spin_unlock(&ses->tcon_ipc->tc_lock);
                }
        }
        spin_unlock(&cifs_tcp_ses_lock);
}

static void
cifs_abort_connection(struct TCP_Server_Info *server)
{
        struct mid_q_entry *mid, *nmid;
        struct list_head retry_list;

        server->maxBuf = 0;
        server->max_read = 0;

        /* do not want to be sending data on a socket we are freeing */
        cifs_dbg(FYI, "%s: tearing down socket\n", __func__);
        cifs_server_lock(server);
        if (server->ssocket) {
                cifs_dbg(FYI, "State: 0x%x Flags: 0x%lx\n", server->ssocket->state,
                         server->ssocket->flags);
                kernel_sock_shutdown(server->ssocket, SHUT_WR);
                cifs_dbg(FYI, "Post shutdown state: 0x%x Flags: 0x%lx\n", server->ssocket->state,
                         server->ssocket->flags);
                sock_release(server->ssocket);
                server->ssocket = NULL;
        } else if (cifs_rdma_enabled(server)) {
                smbd_destroy(server);
        }
        server->sequence_number = 0;
        server->session_estab = false;
        kfree_sensitive(server->session_key.response);
        server->session_key.response = NULL;
        server->session_key.len = 0;
        server->lstrp = jiffies;

        /* mark submitted MIDs for retry and issue callback */
        INIT_LIST_HEAD(&retry_list);
        cifs_dbg(FYI, "%s: moving mids to private list\n", __func__);
        spin_lock(&server->mid_queue_lock);
        list_for_each_entry_safe(mid, nmid, &server->pending_mid_q, qhead) {
                smb_get_mid(mid);
                if (mid->mid_state == MID_REQUEST_SUBMITTED)
                        mid->mid_state = MID_RETRY_NEEDED;
                list_move(&mid->qhead, &retry_list);
                mid->deleted_from_q = true;
        }
        spin_unlock(&server->mid_queue_lock);
        cifs_server_unlock(server);

        cifs_dbg(FYI, "%s: issuing mid callbacks\n", __func__);
        list_for_each_entry_safe(mid, nmid, &retry_list, qhead) {
                list_del_init(&mid->qhead);
                mid_execute_callback(server, mid);
                release_mid(server, mid);
        }
}

static bool cifs_tcp_ses_needs_reconnect(struct TCP_Server_Info *server, int num_targets)
{
        spin_lock(&server->srv_lock);
        server->nr_targets = num_targets;
        if (server->tcpStatus == CifsExiting) {
                /* the demux thread will exit normally next time through the loop */
                spin_unlock(&server->srv_lock);
                wake_up(&server->response_q);
                return false;
        }

        cifs_dbg(FYI, "Mark tcp session as need reconnect\n");
        trace_smb3_reconnect(server->current_mid, server->conn_id,
                             server->hostname);
        server->tcpStatus = CifsNeedReconnect;

        spin_unlock(&server->srv_lock);
        return true;
}

/*
 * cifs tcp session reconnection
 *
 * mark tcp session as reconnecting so temporarily locked
 * mark all smb sessions as reconnecting for tcp session
 * reconnect tcp session
 * wake up waiters on reconnection? - (not needed currently)
 *
 * if mark_smb_session is passed as true, unconditionally mark
 * the smb session (and tcon) for reconnect as well. This value
 * doesn't really matter for non-multichannel scenario.
 *
 */
static int __cifs_reconnect(struct TCP_Server_Info *server,
                            bool mark_smb_session, bool once)
{
        int rc = 0;

        if (!cifs_tcp_ses_needs_reconnect(server, 1))
                return 0;

        /*
         * if smb session has been marked for reconnect, also reconnect all
         * connections. This way, the other connections do not end up bad.
         */
        if (mark_smb_session)
                cifs_signal_cifsd_for_reconnect(server, mark_smb_session);

        cifs_mark_tcp_ses_conns_for_reconnect(server, mark_smb_session);

        cifs_abort_connection(server);

        do {
                try_to_freeze();
                cifs_server_lock(server);

                if (!cifs_swn_set_server_dstaddr(server) &&
                    !SERVER_IS_CHAN(server)) {
                        /* resolve the hostname again to make sure that IP address is up-to-date */
                        rc = reconn_set_ipaddr_from_hostname(server);
                        cifs_dbg(FYI, "%s: reconn_set_ipaddr_from_hostname: rc=%d\n", __func__, rc);
                }

                if (cifs_rdma_enabled(server))
                        rc = smbd_reconnect(server);
                else
                        rc = generic_ip_connect(server);
                if (rc) {
                        cifs_server_unlock(server);
                        cifs_dbg(FYI, "%s: reconnect error %d\n", __func__, rc);
                        /* If was asked to reconnect only once, do not try it more times */
                        if (once)
                                break;
                        msleep(3000);
                } else {
                        atomic_inc(&tcpSesReconnectCount);
                        set_credits(server, 1);
                        spin_lock(&server->srv_lock);
                        if (server->tcpStatus != CifsExiting)
                                server->tcpStatus = CifsNeedNegotiate;
                        spin_unlock(&server->srv_lock);
                        cifs_swn_reset_server_dstaddr(server);
                        cifs_server_unlock(server);
                        cifs_queue_server_reconn(server);
                }
        } while (server->tcpStatus == CifsNeedReconnect);

        spin_lock(&server->srv_lock);
        if (server->tcpStatus == CifsNeedNegotiate)
                mod_delayed_work(cifsiod_wq, &server->echo, 0);
        spin_unlock(&server->srv_lock);

        wake_up(&server->response_q);
        return rc;
}

#ifdef CONFIG_CIFS_DFS_UPCALL
static int __reconnect_target_locked(struct TCP_Server_Info *server,
                                     const char *target)
{
        int rc;
        char *hostname;

        if (!cifs_swn_set_server_dstaddr(server)) {
                if (server->hostname != target) {
                        hostname = extract_hostname(target);
                        if (!IS_ERR(hostname)) {
                                spin_lock(&server->srv_lock);
                                kfree(server->hostname);
                                server->hostname = hostname;
                                spin_unlock(&server->srv_lock);
                        } else {
                                cifs_dbg(FYI, "%s: couldn't extract hostname or address from dfs target: %ld\n",
                                         __func__, PTR_ERR(hostname));
                                cifs_dbg(FYI, "%s: default to last target server: %s\n", __func__,
                                         server->hostname);
                        }
                }
                /* resolve the hostname again to make sure that IP address is up-to-date. */
                rc = reconn_set_ipaddr_from_hostname(server);
                cifs_dbg(FYI, "%s: reconn_set_ipaddr_from_hostname: rc=%d\n", __func__, rc);
        }
        /* Reconnect the socket */
        if (cifs_rdma_enabled(server))
                rc = smbd_reconnect(server);
        else
                rc = generic_ip_connect(server);

        return rc;
}

static int reconnect_target_locked(struct TCP_Server_Info *server,
                                   struct dfs_cache_tgt_list *tl,
                                   struct dfs_cache_tgt_iterator **target_hint)
{
        struct dfs_cache_tgt_iterator *tit;
        int rc;

        *target_hint = NULL;

        /* If dfs target list is empty, then reconnect to last server */
        tit = dfs_cache_get_tgt_iterator(tl);
        if (!tit)
                return __reconnect_target_locked(server, server->hostname);

        /* Otherwise, try every dfs target in @tl */
        do {
                const char *target = dfs_cache_get_tgt_name(tit);

                spin_lock(&server->srv_lock);
                if (server->tcpStatus != CifsNeedReconnect) {
                        spin_unlock(&server->srv_lock);
                        return -ECONNRESET;
                }
                spin_unlock(&server->srv_lock);
                rc = __reconnect_target_locked(server, target);
                if (!rc) {
                        *target_hint = tit;
                        break;
                }
        } while ((tit = dfs_cache_get_next_tgt(tl, tit)));
        return rc;
}

static int reconnect_dfs_server(struct TCP_Server_Info *server)
{
        struct dfs_cache_tgt_iterator *target_hint = NULL;
        const char *ref_path = server->leaf_fullpath + 1;
        DFS_CACHE_TGT_LIST(tl);
        int num_targets = 0;
        int rc = 0;

        /*
         * Determine the number of dfs targets the referral path in @cifs_sb resolves to.
         *
         * smb2_reconnect() needs to know how long it should wait based upon the number of dfs
         * targets (server->nr_targets).  It's also possible that the cached referral was cleared
         * through /proc/fs/cifs/dfscache or the target list is empty due to server settings after
         * refreshing the referral, so, in this case, default it to 1.
         */
        if (!dfs_cache_noreq_find(ref_path, NULL, &tl))
                num_targets = dfs_cache_get_nr_tgts(&tl);
        if (!num_targets)
                num_targets = 1;

        if (!cifs_tcp_ses_needs_reconnect(server, num_targets))
                return 0;

        /*
         * Unconditionally mark all sessions & tcons for reconnect as we might be connecting to a
         * different server or share during failover.  It could be improved by adding some logic to
         * only do that in case it connects to a different server or share, though.
         */
        cifs_mark_tcp_ses_conns_for_reconnect(server, true);

        cifs_abort_connection(server);

        do {
                try_to_freeze();
                cifs_server_lock(server);

                rc = reconnect_target_locked(server, &tl, &target_hint);
                if (rc) {
                        /* Failed to reconnect socket */
                        cifs_server_unlock(server);
                        cifs_dbg(FYI, "%s: reconnect error %d\n", __func__, rc);
                        msleep(3000);
                        continue;
                }
                /*
                 * Socket was created.  Update tcp session status to CifsNeedNegotiate so that a
                 * process waiting for reconnect will know it needs to re-establish session and tcon
                 * through the reconnected target server.
                 */
                atomic_inc(&tcpSesReconnectCount);
                set_credits(server, 1);
                spin_lock(&server->srv_lock);
                if (server->tcpStatus != CifsExiting)
                        server->tcpStatus = CifsNeedNegotiate;
                spin_unlock(&server->srv_lock);
                cifs_swn_reset_server_dstaddr(server);
                cifs_server_unlock(server);
                cifs_queue_server_reconn(server);
        } while (server->tcpStatus == CifsNeedReconnect);

        dfs_cache_noreq_update_tgthint(ref_path, target_hint);
        dfs_cache_free_tgts(&tl);

        /* Need to set up echo worker again once connection has been established */
        spin_lock(&server->srv_lock);
        if (server->tcpStatus == CifsNeedNegotiate)
                mod_delayed_work(cifsiod_wq, &server->echo, 0);
        spin_unlock(&server->srv_lock);

        wake_up(&server->response_q);
        return rc;
}

static int
_cifs_reconnect(struct TCP_Server_Info *server, bool mark_smb_session, bool once)
{
        if (!server->leaf_fullpath)
                return __cifs_reconnect(server, mark_smb_session, once);
        return reconnect_dfs_server(server);
}
#else
static int
_cifs_reconnect(struct TCP_Server_Info *server, bool mark_smb_session, bool once)
{
        return __cifs_reconnect(server, mark_smb_session, once);
}
#endif

int
cifs_reconnect(struct TCP_Server_Info *server, bool mark_smb_session)
{
        return _cifs_reconnect(server, mark_smb_session, false);
}

static int
cifs_reconnect_once(struct TCP_Server_Info *server)
{
        return _cifs_reconnect(server, true, true);
}

static void
cifs_echo_request(struct work_struct *work)
{
        int rc;
        struct TCP_Server_Info *server = container_of(work,
                                        struct TCP_Server_Info, echo.work);

        /*
         * We cannot send an echo if it is disabled.
         * Also, no need to ping if we got a response recently.
         */

        if (server->tcpStatus == CifsNeedReconnect ||
            server->tcpStatus == CifsExiting ||
            server->tcpStatus == CifsNew ||
            (server->ops->can_echo && !server->ops->can_echo(server)) ||
            time_before(jiffies, server->lstrp + server->echo_interval - HZ))
                goto requeue_echo;

        rc = server->ops->echo ? server->ops->echo(server) : -ENOSYS;
        cifs_server_dbg(FYI, "send echo request: rc = %d\n", rc);

        /* Check witness registrations */
        cifs_swn_check();

requeue_echo:
        queue_delayed_work(cifsiod_wq, &server->echo, server->echo_interval);
}

static bool
allocate_buffers(struct TCP_Server_Info *server)
{
        if (!server->bigbuf) {
                server->bigbuf = (char *)cifs_buf_get();
                if (!server->bigbuf) {
                        cifs_server_dbg(VFS, "No memory for large SMB response\n");
                        msleep(3000);
                        /* retry will check if exiting */
                        return false;
                }
        } else if (server->large_buf) {
                /* we are reusing a dirty large buf, clear its start */
                memset(server->bigbuf, 0, HEADER_SIZE(server));
        }

        if (!server->smallbuf) {
                server->smallbuf = (char *)cifs_small_buf_get();
                if (!server->smallbuf) {
                        cifs_server_dbg(VFS, "No memory for SMB response\n");
                        msleep(1000);
                        /* retry will check if exiting */
                        return false;
                }
                /* beginning of smb buffer is cleared in our buf_get */
        } else {
                /* if existing small buf clear beginning */
                memset(server->smallbuf, 0, HEADER_SIZE(server));
        }

        return true;
}

static bool
server_unresponsive(struct TCP_Server_Info *server)
{
        /*
         * If we're in the process of mounting a share or reconnecting a session
         * and the server abruptly shut down (e.g. socket wasn't closed, packet
         * had been ACK'ed but no SMB response), don't wait longer than 20s from
         * when negotiate actually started.
         */
        spin_lock(&server->srv_lock);
        if (server->tcpStatus == CifsInNegotiate &&
            time_after(jiffies, server->neg_start + 20 * HZ)) {
                spin_unlock(&server->srv_lock);
                cifs_reconnect(server, false);
                return true;
        }
        /*
         * We need to wait 3 echo intervals to make sure we handle such
         * situations right:
         * 1s  client sends a normal SMB request
         * 2s  client gets a response
         * 30s echo workqueue job pops, and decides we got a response recently
         *     and don't need to send another
         * ...
         * 65s kernel_recvmsg times out, and we see that we haven't gotten
         *     a response in >60s.
         */
        if ((server->tcpStatus == CifsGood ||
            server->tcpStatus == CifsNeedNegotiate) &&
            (!server->ops->can_echo || server->ops->can_echo(server)) &&
            time_after(jiffies, server->lstrp + 3 * server->echo_interval)) {
                spin_unlock(&server->srv_lock);
                cifs_server_dbg(VFS, "has not responded in %lu seconds. Reconnecting...\n",
                         (3 * server->echo_interval) / HZ);
                cifs_reconnect(server, false);
                return true;
        }
        spin_unlock(&server->srv_lock);

        return false;
}

static inline bool
zero_credits(struct TCP_Server_Info *server)
{
        int val;

        spin_lock(&server->req_lock);
        val = server->credits + server->echo_credits + server->oplock_credits;
        if (server->in_flight == 0 && val == 0) {
                spin_unlock(&server->req_lock);
                return true;
        }
        spin_unlock(&server->req_lock);
        return false;
}

static int
cifs_readv_from_socket(struct TCP_Server_Info *server, struct msghdr *smb_msg)
{
        int length = 0;
        int total_read;

        for (total_read = 0; msg_data_left(smb_msg); total_read += length) {
                try_to_freeze();

                /* reconnect if no credits and no requests in flight */
                if (zero_credits(server)) {
                        cifs_reconnect(server, false);
                        return -ECONNABORTED;
                }

                if (server_unresponsive(server))
                        return -ECONNABORTED;
                if (cifs_rdma_enabled(server) && server->smbd_conn)
                        length = smbd_recv(server->smbd_conn, smb_msg);
                else
                        length = sock_recvmsg(server->ssocket, smb_msg, 0);

                spin_lock(&server->srv_lock);
                if (server->tcpStatus == CifsExiting) {
                        spin_unlock(&server->srv_lock);
                        return -ESHUTDOWN;
                }

                if (server->tcpStatus == CifsNeedReconnect) {
                        spin_unlock(&server->srv_lock);
                        cifs_reconnect(server, false);
                        return -ECONNABORTED;
                }
                spin_unlock(&server->srv_lock);

                if (length == -ERESTARTSYS ||
                    length == -EAGAIN ||
                    length == -EINTR) {
                        /*
                         * Minimum sleep to prevent looping, allowing socket
                         * to clear and app threads to set tcpStatus
                         * CifsNeedReconnect if server hung.
                         */
                        usleep_range(1000, 2000);
                        length = 0;
                        continue;
                }

                if (length <= 0) {
                        cifs_dbg(FYI, "Received no data or error: %d\n", length);
                        cifs_reconnect(server, false);
                        return -ECONNABORTED;
                }
        }
        return total_read;
}

int
cifs_read_from_socket(struct TCP_Server_Info *server, char *buf,
                      unsigned int to_read)
{
        struct msghdr smb_msg = {};
        struct kvec iov = {.iov_base = buf, .iov_len = to_read};

        iov_iter_kvec(&smb_msg.msg_iter, ITER_DEST, &iov, 1, to_read);

        return cifs_readv_from_socket(server, &smb_msg);
}

ssize_t
cifs_discard_from_socket(struct TCP_Server_Info *server, size_t to_read)
{
        struct msghdr smb_msg = {};

        /*
         *  iov_iter_discard already sets smb_msg.type and count and iov_offset
         *  and cifs_readv_from_socket sets msg_control and msg_controllen
         *  so little to initialize in struct msghdr
         */
        iov_iter_discard(&smb_msg.msg_iter, ITER_DEST, to_read);

        return cifs_readv_from_socket(server, &smb_msg);
}

int
cifs_read_iter_from_socket(struct TCP_Server_Info *server, struct iov_iter *iter,
                           unsigned int to_read)
{
        struct msghdr smb_msg = { .msg_iter = *iter };

        iov_iter_truncate(&smb_msg.msg_iter, to_read);
        return cifs_readv_from_socket(server, &smb_msg);
}

static bool
is_smb_response(struct TCP_Server_Info *server, unsigned char type)
{
        /*
         * The first byte big endian of the length field,
         * is actually not part of the length but the type
         * with the most common, zero, as regular data.
         */
        switch (type) {
        case RFC1002_SESSION_MESSAGE:
                /* Regular SMB response */
                return true;
        case RFC1002_SESSION_KEEP_ALIVE:
                /*
                 * RFC 1002 session keep alive can sent by the server only when
                 * we established a RFC 1002 session. But Samba servers send
                 * RFC 1002 session keep alive also over port 445 on which
                 * RFC 1002 session is not established.
                 */
                cifs_dbg(FYI, "RFC 1002 session keep alive\n");
                break;
        case RFC1002_POSITIVE_SESSION_RESPONSE:
                /*
                 * RFC 1002 positive session response cannot be returned
                 * for SMB request. RFC 1002 session response is handled
                 * exclusively in ip_rfc1001_connect() function.
                 */
                cifs_server_dbg(VFS, "RFC 1002 positive session response (unexpected)\n");
                cifs_reconnect(server, true);
                break;
        case RFC1002_NEGATIVE_SESSION_RESPONSE:
                /*
                 * We get this from Windows 98 instead of an error on
                 * SMB negprot response, when we have not established
                 * RFC 1002 session (which means ip_rfc1001_connect()
                 * was skipped). Note that same still happens with
                 * Windows Server 2022 when connecting via port 139.
                 * So for this case when mount option -o nonbsessinit
                 * was not specified, try to reconnect with establishing
                 * RFC 1002 session. If new socket establishment with
                 * RFC 1002 session was successful then return to the
                 * mid's caller -EAGAIN, so it can retry the request.
                 */
                if (!cifs_rdma_enabled(server) &&
                    server->tcpStatus == CifsInNegotiate &&
                    !server->with_rfc1001 &&
                    server->rfc1001_sessinit != 0) {
                        int rc, mid_rc;
                        struct mid_q_entry *mid, *nmid;
                        LIST_HEAD(dispose_list);

                        cifs_dbg(FYI, "RFC 1002 negative session response during SMB Negotiate, retrying with NetBIOS session\n");

                        /*
                         * Before reconnect, delete all pending mids for this
                         * server, so reconnect would not signal connection
                         * aborted error to mid's callbacks. Note that for this
                         * server there should be exactly one pending mid
                         * corresponding to SMB1/SMB2 Negotiate packet.
                         */
                        spin_lock(&server->mid_queue_lock);
                        list_for_each_entry_safe(mid, nmid, &server->pending_mid_q, qhead) {
                                smb_get_mid(mid);
                                list_move(&mid->qhead, &dispose_list);
                                mid->deleted_from_q = true;
                        }
                        spin_unlock(&server->mid_queue_lock);

                        /* Now try to reconnect once with NetBIOS session. */
                        server->with_rfc1001 = true;
                        rc = cifs_reconnect_once(server);

                        /*
                         * If reconnect was successful then indicate -EAGAIN
                         * to mid's caller. If reconnect failed with -EAGAIN
                         * then mask it as -EHOSTDOWN, so mid's caller would
                         * know that it failed.
                         */
                        if (rc == 0)
                                mid_rc = -EAGAIN;
                        else if (rc == -EAGAIN)
                                mid_rc = -EHOSTDOWN;
                        else
                                mid_rc = rc;

                        /*
                         * After reconnect (either successful or unsuccessful)
                         * deliver reconnect status to mid's caller via mid's
                         * callback. Use MID_RC state which indicates that the
                         * return code should be read from mid_rc member.
                         */
                        list_for_each_entry_safe(mid, nmid, &dispose_list, qhead) {
                                list_del_init(&mid->qhead);
                                mid->mid_rc = mid_rc;
                                mid->mid_state = MID_RC;
                                mid_execute_callback(server, mid);
                                release_mid(server, mid);
                        }

                        /*
                         * If reconnect failed then wait two seconds. In most
                         * cases we were been called from the mount context and
                         * delivered failure to mid's callback will stop this
                         * receiver task thread and fails the mount process.
                         * So wait two seconds to prevent another reconnect
                         * in this task thread, which would be useless as the
                         * mount context will fail at all.
                         */
                        if (rc != 0)
                                msleep(2000);
                } else {
                        cifs_server_dbg(VFS, "RFC 1002 negative session response (unexpected)\n");
                        cifs_reconnect(server, true);
                }
                break;
        case RFC1002_RETARGET_SESSION_RESPONSE:
                cifs_server_dbg(VFS, "RFC 1002 retarget session response (unexpected)\n");
                cifs_reconnect(server, true);
                break;
        default:
                cifs_server_dbg(VFS, "RFC 1002 unknown response type 0x%x\n", type);
                cifs_reconnect(server, true);
        }

        return false;
}

void
dequeue_mid(struct TCP_Server_Info *server, struct mid_q_entry *mid, bool malformed)
{
#ifdef CONFIG_CIFS_STATS2
        mid->when_received = jiffies;
#endif
        spin_lock(&server->mid_queue_lock);
        if (!malformed)
                mid->mid_state = MID_RESPONSE_RECEIVED;
        else
                mid->mid_state = MID_RESPONSE_MALFORMED;
        /*
         * Trying to handle/dequeue a mid after the send_recv()
         * function has finished processing it is a bug.
         */
        if (mid->deleted_from_q == true) {
                spin_unlock(&server->mid_queue_lock);
                pr_warn_once("trying to dequeue a deleted mid\n");
        } else {
                list_del_init(&mid->qhead);
                mid->deleted_from_q = true;
                spin_unlock(&server->mid_queue_lock);
        }
}

static unsigned int
smb2_get_credits_from_hdr(char *buffer, struct TCP_Server_Info *server)
{
        struct smb2_hdr *shdr = (struct smb2_hdr *)buffer;

        /*
         * SMB1 does not use credits.
         */
        if (is_smb1(server))
                return 0;

        return le16_to_cpu(shdr->CreditRequest);
}

static void
handle_mid(struct mid_q_entry *mid, struct TCP_Server_Info *server,
           char *buf, int malformed)
{
        if (server->ops->check_trans2 &&
            server->ops->check_trans2(mid, server, buf, malformed))
                return;
        mid->credits_received = smb2_get_credits_from_hdr(buf, server);
        mid->resp_buf = buf;
        mid->large_buf = server->large_buf;
        /* Was previous buf put in mpx struct for multi-rsp? */
        if (!mid->multiRsp) {
                /* smb buffer will be freed by user thread */
                if (server->large_buf)
                        server->bigbuf = NULL;
                else
                        server->smallbuf = NULL;
        }
        dequeue_mid(server, mid, malformed);
}

int
cifs_enable_signing(struct TCP_Server_Info *server, bool mnt_sign_required)
{
        bool srv_sign_required = server->sec_mode & server->vals->signing_required;
        bool srv_sign_enabled = server->sec_mode & server->vals->signing_enabled;
        bool mnt_sign_enabled;

        /*
         * Is signing required by mnt options? If not then check
         * global_secflags to see if it is there.
         */
        if (!mnt_sign_required)
                mnt_sign_required = ((global_secflags & CIFSSEC_MUST_SIGN) ==
                                                CIFSSEC_MUST_SIGN);

        /*
         * If signing is required then it's automatically enabled too,
         * otherwise, check to see if the secflags allow it.
         */
        mnt_sign_enabled = mnt_sign_required ? mnt_sign_required :
                                (global_secflags & CIFSSEC_MAY_SIGN);

        /* If server requires signing, does client allow it? */
        if (srv_sign_required) {
                if (!mnt_sign_enabled) {
                        cifs_dbg(VFS, "Server requires signing, but it's disabled in SecurityFlags!\n");
                        return -EOPNOTSUPP;
                }
                server->sign = true;
        }

        /* If client requires signing, does server allow it? */
        if (mnt_sign_required) {
                if (!srv_sign_enabled) {
                        cifs_dbg(VFS, "Server does not support signing!\n");
                        return -EOPNOTSUPP;
                }
                server->sign = true;
        }

        if (cifs_rdma_enabled(server) && server->sign)
                cifs_dbg(VFS, "Signing is enabled, and RDMA read/write will be disabled\n");

        return 0;
}

static noinline_for_stack void
clean_demultiplex_info(struct TCP_Server_Info *server)
{
        int length;

        /* take it off the list, if it's not already */
        spin_lock(&server->srv_lock);
        list_del_init(&server->tcp_ses_list);
        spin_unlock(&server->srv_lock);

        cancel_delayed_work_sync(&server->echo);

        spin_lock(&server->srv_lock);
        server->tcpStatus = CifsExiting;
        spin_unlock(&server->srv_lock);
        wake_up_all(&server->response_q);

        /* check if we have blocked requests that need to free */
        spin_lock(&server->req_lock);
        if (server->credits <= 0)
                server->credits = 1;
        spin_unlock(&server->req_lock);
        /*
         * Although there should not be any requests blocked on this queue it
         * can not hurt to be paranoid and try to wake up requests that may
         * haven been blocked when more than 50 at time were on the wire to the
         * same server - they now will see the session is in exit state and get
         * out of SendReceive.
         */
        wake_up_all(&server->request_q);
        /* give those requests time to exit */
        msleep(125);
        if (cifs_rdma_enabled(server))
                smbd_destroy(server);
        if (server->ssocket) {
                sock_release(server->ssocket);
                server->ssocket = NULL;
        }

        if (!list_empty(&server->pending_mid_q)) {
                struct mid_q_entry *mid_entry;
                struct list_head *tmp, *tmp2;
                LIST_HEAD(dispose_list);

                spin_lock(&server->mid_queue_lock);
                list_for_each_safe(tmp, tmp2, &server->pending_mid_q) {
                        mid_entry = list_entry(tmp, struct mid_q_entry, qhead);
                        cifs_dbg(FYI, "Clearing mid %llu\n", mid_entry->mid);
                        smb_get_mid(mid_entry);
                        mid_entry->mid_state = MID_SHUTDOWN;
                        list_move(&mid_entry->qhead, &dispose_list);
                        mid_entry->deleted_from_q = true;
                }
                spin_unlock(&server->mid_queue_lock);

                /* now walk dispose list and issue callbacks */
                list_for_each_safe(tmp, tmp2, &dispose_list) {
                        mid_entry = list_entry(tmp, struct mid_q_entry, qhead);
                        cifs_dbg(FYI, "Callback mid %llu\n", mid_entry->mid);
                        list_del_init(&mid_entry->qhead);
                        mid_execute_callback(server, mid_entry);
                        release_mid(server, mid_entry);
                }
                /* 1/8th of sec is more than enough time for them to exit */
                msleep(125);
        }

        if (!list_empty(&server->pending_mid_q)) {
                /*
                 * mpx threads have not exited yet give them at least the smb
                 * send timeout time for long ops.
                 *
                 * Due to delays on oplock break requests, we need to wait at
                 * least 45 seconds before giving up on a request getting a
                 * response and going ahead and killing cifsd.
                 */
                cifs_dbg(FYI, "Wait for exit from demultiplex thread\n");
                msleep(46000);
                /*
                 * If threads still have not exited they are probably never
                 * coming home not much else we can do but free the memory.
                 */
        }

        put_net(cifs_net_ns(server));
        kfree(server->leaf_fullpath);
        kfree(server->hostname);
        kfree(server);

        length = atomic_dec_return(&tcpSesAllocCount);
        if (length > 0)
                mempool_resize(cifs_req_poolp, length + cifs_min_rcv);
}

static int
standard_receive3(struct TCP_Server_Info *server, struct mid_q_entry *mid)
{
        int length;
        char *buf = server->smallbuf;
        unsigned int pdu_length = server->pdu_size;

        /* make sure this will fit in a large buffer */
        if (pdu_length > CIFSMaxBufSize + MAX_HEADER_SIZE(server)) {
                cifs_server_dbg(VFS, "SMB response too long (%u bytes)\n", pdu_length);
                cifs_reconnect(server, true);
                return -ECONNABORTED;
        }

        /* switch to large buffer if too big for a small one */
        if (pdu_length > MAX_CIFS_SMALL_BUFFER_SIZE) {
                server->large_buf = true;
                memcpy(server->bigbuf, buf, server->total_read);
                buf = server->bigbuf;
        }

        /* now read the rest */
        length = cifs_read_from_socket(server, buf + HEADER_SIZE(server) - 1,
                                       pdu_length - MID_HEADER_SIZE(server));

        if (length < 0)
                return length;
        server->total_read += length;

        dump_smb(buf, server->total_read);

        return cifs_handle_standard(server, mid);
}

int
cifs_handle_standard(struct TCP_Server_Info *server, struct mid_q_entry *mid)
{
        char *buf = server->large_buf ? server->bigbuf : server->smallbuf;
        int rc;

        /*
         * We know that we received enough to get to the MID as we
         * checked the pdu_length earlier. Now check to see
         * if the rest of the header is OK.
         *
         * 48 bytes is enough to display the header and a little bit
         * into the payload for debugging purposes.
         */
        rc = server->ops->check_message(buf, server->pdu_size,
                                        server->total_read, server);
        if (rc)
                cifs_dump_mem("Bad SMB: ", buf,
                        min_t(unsigned int, server->total_read, 48));

        if (server->ops->is_session_expired &&
            server->ops->is_session_expired(buf)) {
                cifs_reconnect(server, true);
                return -1;
        }

        if (server->ops->is_status_pending &&
            server->ops->is_status_pending(buf, server))
                return -1;

        if (!mid)
                return rc;

        handle_mid(mid, server, buf, rc);
        return 0;
}

static void
smb2_add_credits_from_hdr(char *buffer, struct TCP_Server_Info *server)
{
        struct smb2_hdr *shdr = (struct smb2_hdr *)buffer;
        int scredits, in_flight;

        /*
         * SMB1 does not use credits.
         */
        if (is_smb1(server))
                return;

        if (shdr->CreditRequest) {
                spin_lock(&server->req_lock);
                server->credits += le16_to_cpu(shdr->CreditRequest);
                scredits = server->credits;
                in_flight = server->in_flight;
                spin_unlock(&server->req_lock);
                wake_up(&server->request_q);

                trace_smb3_hdr_credits(server->current_mid,
                                server->conn_id, server->hostname, scredits,
                                le16_to_cpu(shdr->CreditRequest), in_flight);
                cifs_server_dbg(FYI, "%s: added %u credits total=%d\n",
                                __func__, le16_to_cpu(shdr->CreditRequest),
                                scredits);
        }
}


static int
cifs_demultiplex_thread(void *p)
{
        int i, num_mids, length;
        struct TCP_Server_Info *server = p;
        unsigned int pdu_length;
        unsigned int next_offset;
        char *buf = NULL;
        struct task_struct *task_to_wake = NULL;
        struct mid_q_entry *mids[MAX_COMPOUND];
        char *bufs[MAX_COMPOUND];
        unsigned int noreclaim_flag, num_io_timeout = 0;
        bool pending_reconnect = false;

        noreclaim_flag = memalloc_noreclaim_save();
        cifs_dbg(FYI, "Demultiplex PID: %d\n", task_pid_nr(current));

        length = atomic_inc_return(&tcpSesAllocCount);
        if (length > 1)
                mempool_resize(cifs_req_poolp, length + cifs_min_rcv);

        set_freezable();
        allow_kernel_signal(SIGKILL);
        while (server->tcpStatus != CifsExiting) {
                if (try_to_freeze())
                        continue;

                if (!allocate_buffers(server))
                        continue;

                server->large_buf = false;
                buf = server->smallbuf;
                pdu_length = 4; /* enough to get RFC1001 header */

                length = cifs_read_from_socket(server, buf, pdu_length);
                if (length < 0)
                        continue;

                server->total_read = 0;

                /*
                 * The right amount was read from socket - 4 bytes,
                 * so we can now interpret the length field.
                 */
                pdu_length = be32_to_cpup(((__be32 *)buf)) & 0xffffff;

                cifs_dbg(FYI, "RFC1002 header 0x%x\n", pdu_length);
                if (!is_smb_response(server, buf[0]))
                        continue;

                pending_reconnect = false;
next_pdu:
                server->pdu_size = pdu_length;

                /* make sure we have enough to get to the MID */
                if (server->pdu_size < MID_HEADER_SIZE(server)) {
                        cifs_server_dbg(VFS, "SMB response too short (%u bytes)\n",
                                 server->pdu_size);
                        cifs_reconnect(server, true);
                        continue;
                }

                /* read down to the MID */
                length = cifs_read_from_socket(server, buf,
                                               MID_HEADER_SIZE(server));
                if (length < 0)
                        continue;
                server->total_read += length;

                if (server->ops->next_header) {
                        if (server->ops->next_header(server, buf, &next_offset)) {
                                cifs_dbg(VFS, "%s: malformed response (next_offset=%u)\n",
                                         __func__, next_offset);
                                cifs_reconnect(server, true);
                                continue;
                        }
                        if (next_offset)
                                server->pdu_size = next_offset;
                }

                memset(mids, 0, sizeof(mids));
                memset(bufs, 0, sizeof(bufs));
                num_mids = 0;

                if (server->ops->is_transform_hdr &&
                    server->ops->receive_transform &&
                    server->ops->is_transform_hdr(buf)) {
                        length = server->ops->receive_transform(server,
                                                                mids,
                                                                bufs,
                                                                &num_mids);
                } else {
                        mids[0] = server->ops->find_mid(server, buf);
                        bufs[0] = buf;
                        num_mids = 1;

                        if (mids[0])
                                mids[0]->response_pdu_len = pdu_length;
                        if (!mids[0] || !mids[0]->receive)
                                length = standard_receive3(server, mids[0]);
                        else
                                length = mids[0]->receive(server, mids[0]);
                }

                if (length < 0) {
                        for (i = 0; i < num_mids; i++)
                                if (mids[i])
                                        release_mid(server, mids[i]);
                        continue;
                }

                if (server->ops->is_status_io_timeout &&
                    server->ops->is_status_io_timeout(buf)) {
                        num_io_timeout++;
                        if (num_io_timeout > MAX_STATUS_IO_TIMEOUT) {
                                cifs_server_dbg(VFS,
                                                "Number of request timeouts exceeded %d. Reconnecting",
                                                MAX_STATUS_IO_TIMEOUT);

                                pending_reconnect = true;
                                num_io_timeout = 0;
                        }
                }

                server->lstrp = jiffies;

                for (i = 0; i < num_mids; i++) {
                        if (mids[i] != NULL) {
                                mids[i]->resp_buf_size = server->pdu_size;

                                if (bufs[i] != NULL) {
                                        if (server->ops->is_network_name_deleted &&
                                            server->ops->is_network_name_deleted(bufs[i],
                                                                                 server)) {
                                                cifs_server_dbg(FYI,
                                                                "Share deleted. Reconnect needed");
                                        }
                                }

                                if (!mids[i]->multiRsp || mids[i]->multiEnd)
                                        mid_execute_callback(server, mids[i]);

                                release_mid(server, mids[i]);
                        } else if (server->ops->is_oplock_break &&
                                   server->ops->is_oplock_break(bufs[i],
                                                                server)) {
                                smb2_add_credits_from_hdr(bufs[i], server);
                                cifs_dbg(FYI, "Received oplock break\n");
                        } else {
                                cifs_server_dbg(VFS, "No task to wake, unknown frame received! NumMids %d\n",
                                                atomic_read(&mid_count));
                                cifs_dump_mem("Received Data is: ", bufs[i],
                                              HEADER_SIZE(server));
                                smb2_add_credits_from_hdr(bufs[i], server);
#ifdef CONFIG_CIFS_DEBUG2
                                if (server->ops->dump_detail)
                                        server->ops->dump_detail(bufs[i], pdu_length,
                                                                 server);
                                cifs_dump_mids(server);
#endif /* CIFS_DEBUG2 */
                        }
                }

                if (pdu_length > server->pdu_size) {
                        if (!allocate_buffers(server))
                                continue;
                        pdu_length -= server->pdu_size;
                        server->total_read = 0;
                        server->large_buf = false;
                        buf = server->smallbuf;
                        goto next_pdu;
                }

                /* do this reconnect at the very end after processing all MIDs */
                if (pending_reconnect)
                        cifs_reconnect(server, true);

        } /* end while !EXITING */

        /* buffer usually freed in free_mid - need to free it here on exit */
        cifs_buf_release(server->bigbuf);
        if (server->smallbuf) /* no sense logging a debug message if NULL */
                cifs_small_buf_release(server->smallbuf);

        task_to_wake = xchg(&server->tsk, NULL);
        clean_demultiplex_info(server);

        /* if server->tsk was NULL then wait for a signal before exiting */
        if (!task_to_wake) {
                set_current_state(TASK_INTERRUPTIBLE);
                while (!signal_pending(current)) {
                        schedule();
                        set_current_state(TASK_INTERRUPTIBLE);
                }
                set_current_state(TASK_RUNNING);
        }

        memalloc_noreclaim_restore(noreclaim_flag);
        module_put_and_kthread_exit(0);
}

int
cifs_ipaddr_cmp(struct sockaddr *srcaddr, struct sockaddr *rhs)
{
        struct sockaddr_in *saddr4 = (struct sockaddr_in *)srcaddr;
        struct sockaddr_in *vaddr4 = (struct sockaddr_in *)rhs;
        struct sockaddr_in6 *saddr6 = (struct sockaddr_in6 *)srcaddr;
        struct sockaddr_in6 *vaddr6 = (struct sockaddr_in6 *)rhs;

        switch (srcaddr->sa_family) {
        case AF_UNSPEC:
                switch (rhs->sa_family) {
                case AF_UNSPEC:
                        return 0;
                case AF_INET:
                case AF_INET6:
                        return 1;
                default:
                        return -1;
                }
        case AF_INET: {
                switch (rhs->sa_family) {
                case AF_UNSPEC:
                        return -1;
                case AF_INET:
                        return memcmp(saddr4, vaddr4,
                                      sizeof(struct sockaddr_in));
                case AF_INET6:
                        return 1;
                default:
                        return -1;
                }
        }
        case AF_INET6: {
                switch (rhs->sa_family) {
                case AF_UNSPEC:
                case AF_INET:
                        return -1;
                case AF_INET6:
                        return memcmp(saddr6,
                                      vaddr6,
                                      sizeof(struct sockaddr_in6));
                default:
                        return -1;
                }
        }
        default:
                return -1; /* don't expect to be here */
        }
}

/*
 * Returns true if srcaddr isn't specified and rhs isn't specified, or
 * if srcaddr is specified and matches the IP address of the rhs argument
 */
bool
cifs_match_ipaddr(struct sockaddr *srcaddr, struct sockaddr *rhs)
{
        switch (srcaddr->sa_family) {
        case AF_UNSPEC:
                return (rhs->sa_family == AF_UNSPEC);
        case AF_INET: {
                struct sockaddr_in *saddr4 = (struct sockaddr_in *)srcaddr;
                struct sockaddr_in *vaddr4 = (struct sockaddr_in *)rhs;

                return (saddr4->sin_addr.s_addr == vaddr4->sin_addr.s_addr);
        }
        case AF_INET6: {
                struct sockaddr_in6 *saddr6 = (struct sockaddr_in6 *)srcaddr;
                struct sockaddr_in6 *vaddr6 = (struct sockaddr_in6 *)rhs;

                return (ipv6_addr_equal(&saddr6->sin6_addr, &vaddr6->sin6_addr)
                        && saddr6->sin6_scope_id == vaddr6->sin6_scope_id);
        }
        default:
                WARN_ON(1);
                return false; /* don't expect to be here */
        }
}

/*
 * If no port is specified in addr structure, we try to match with 445 port
 * and if it fails - with 139 ports. It should be called only if address
 * families of server and addr are equal.
 */
static bool
match_port(struct TCP_Server_Info *server, struct sockaddr *addr)
{
        __be16 port, *sport;

        /* SMBDirect manages its own ports, don't match it here */
        if (server->rdma)
                return true;

        switch (addr->sa_family) {
        case AF_INET:
                sport = &((struct sockaddr_in *) &server->dstaddr)->sin_port;
                port = ((struct sockaddr_in *) addr)->sin_port;
                break;
        case AF_INET6:
                sport = &((struct sockaddr_in6 *) &server->dstaddr)->sin6_port;
                port = ((struct sockaddr_in6 *) addr)->sin6_port;
                break;
        default:
                WARN_ON(1);
                return false;
        }

        if (!port) {
                port = htons(CIFS_PORT);
                if (port == *sport)
                        return true;

                port = htons(RFC1001_PORT);
        }

        return port == *sport;
}

static bool match_server_address(struct TCP_Server_Info *server, struct sockaddr *addr)
{
        if (!cifs_match_ipaddr(addr, (struct sockaddr *)&server->dstaddr))
                return false;

        return true;
}

static bool
match_security(struct TCP_Server_Info *server, struct smb3_fs_context *ctx)
{
        /*
         * The select_sectype function should either return the ctx->sectype
         * that was specified, or "Unspecified" if that sectype was not
         * compatible with the given NEGOTIATE request.
         */
        if (server->ops->select_sectype(server, ctx->sectype)
             == Unspecified)
                return false;

        /*
         * Now check if signing mode is acceptable. No need to check
         * global_secflags at this point since if MUST_SIGN is set then
         * the server->sign had better be too.
         */
        if (ctx->sign && !server->sign)
                return false;

        return true;
}

/* this function must be called with srv_lock held */
static int match_server(struct TCP_Server_Info *server,
                        struct smb3_fs_context *ctx,
                        bool match_super)
{
        struct sockaddr *addr = (struct sockaddr *)&ctx->dstaddr;

        lockdep_assert_held(&server->srv_lock);

        if (ctx->nosharesock)
                return 0;

        /* this server does not share socket */
        if (server->nosharesock)
                return 0;

        if (!match_super && (ctx->dfs_conn || server->dfs_conn))
                return 0;

        /* If multidialect negotiation see if existing sessions match one */
        if (strcmp(ctx->vals->version_string, SMB3ANY_VERSION_STRING) == 0) {
                if (server->vals->protocol_id < SMB30_PROT_ID)
                        return 0;
        } else if (strcmp(ctx->vals->version_string,
                   SMBDEFAULT_VERSION_STRING) == 0) {
                if (server->vals->protocol_id < SMB21_PROT_ID)
                        return 0;
        } else if ((server->vals != ctx->vals) || (server->ops != ctx->ops))
                return 0;

        if (!net_eq(cifs_net_ns(server), current->nsproxy->net_ns))
                return 0;

        if (!cifs_match_ipaddr((struct sockaddr *)&ctx->srcaddr,
                               (struct sockaddr *)&server->srcaddr))
                return 0;

        if (strcasecmp(server->hostname, ctx->server_hostname) ||
            !match_server_address(server, addr) ||
            !match_port(server, addr))
                return 0;

        if (!match_security(server, ctx))
                return 0;

        if (server->echo_interval != ctx->echo_interval * HZ)
                return 0;

        if (server->rdma != ctx->rdma)
                return 0;

        if (server->ignore_signature != ctx->ignore_signature)
                return 0;

        if (server->min_offload != ctx->min_offload)
                return 0;

        if (server->retrans != ctx->retrans)
                return 0;

        return 1;
}

struct TCP_Server_Info *
cifs_find_tcp_session(struct smb3_fs_context *ctx)
{
        struct TCP_Server_Info *server;

        spin_lock(&cifs_tcp_ses_lock);
        list_for_each_entry(server, &cifs_tcp_ses_list, tcp_ses_list) {
                spin_lock(&server->srv_lock);
                /*
                 * Skip ses channels since they're only handled in lower layers
                 * (e.g. cifs_send_recv).
                 */
                if (SERVER_IS_CHAN(server) ||
                    !match_server(server, ctx, false)) {
                        spin_unlock(&server->srv_lock);
                        continue;
                }
                spin_unlock(&server->srv_lock);

                ++server->srv_count;
                spin_unlock(&cifs_tcp_ses_lock);
                cifs_dbg(FYI, "Existing tcp session with server found\n");
                return server;
        }
        spin_unlock(&cifs_tcp_ses_lock);
        return NULL;
}

void
cifs_put_tcp_session(struct TCP_Server_Info *server, int from_reconnect)
{
        struct task_struct *task;

        spin_lock(&cifs_tcp_ses_lock);
        if (--server->srv_count > 0) {
                spin_unlock(&cifs_tcp_ses_lock);
                return;
        }

        /* srv_count can never go negative */
        WARN_ON(server->srv_count < 0);

        list_del_init(&server->tcp_ses_list);
        spin_unlock(&cifs_tcp_ses_lock);

        cancel_delayed_work_sync(&server->echo);

        if (from_reconnect)
                /*
                 * Avoid deadlock here: reconnect work calls
                 * cifs_put_tcp_session() at its end. Need to be sure
                 * that reconnect work does nothing with server pointer after
                 * that step.
                 */
                cancel_delayed_work(&server->reconnect);
        else
                cancel_delayed_work_sync(&server->reconnect);

        /* For secondary channels, we pick up ref-count on the primary server */
        if (SERVER_IS_CHAN(server))
                cifs_put_tcp_session(server->primary_server, from_reconnect);

        spin_lock(&server->srv_lock);
        server->tcpStatus = CifsExiting;
        spin_unlock(&server->srv_lock);

        cifs_crypto_secmech_release(server);

        kfree_sensitive(server->session_key.response);
        server->session_key.response = NULL;
        server->session_key.len = 0;

        task = xchg(&server->tsk, NULL);
        if (task)
                send_sig(SIGKILL, task, 1);
}

struct TCP_Server_Info *
cifs_get_tcp_session(struct smb3_fs_context *ctx,
                     struct TCP_Server_Info *primary_server)
{
        struct TCP_Server_Info *tcp_ses = NULL;
        int rc;

        cifs_dbg(FYI, "UNC: %s\n", ctx->UNC);

        /* see if we already have a matching tcp_ses */
        tcp_ses = cifs_find_tcp_session(ctx);
        if (tcp_ses)
                return tcp_ses;

        tcp_ses = kzalloc_obj(struct TCP_Server_Info);
        if (!tcp_ses) {
                rc = -ENOMEM;
                goto out_err;
        }

        tcp_ses->hostname = kstrdup(ctx->server_hostname, GFP_KERNEL);
        if (!tcp_ses->hostname) {
                rc = -ENOMEM;
                goto out_err;
        }

        if (ctx->leaf_fullpath) {
                tcp_ses->leaf_fullpath = kstrdup(ctx->leaf_fullpath, GFP_KERNEL);
                if (!tcp_ses->leaf_fullpath) {
                        rc = -ENOMEM;
                        goto out_err;
                }
        }
        if (ctx->dns_dom)
                strscpy(tcp_ses->dns_dom, ctx->dns_dom);

        if (ctx->nosharesock)
                tcp_ses->nosharesock = true;
        tcp_ses->dfs_conn = ctx->dfs_conn;

        tcp_ses->ops = ctx->ops;
        tcp_ses->vals = ctx->vals;
        cifs_set_net_ns(tcp_ses, get_net(current->nsproxy->net_ns));

        tcp_ses->sign = ctx->sign;
        tcp_ses->conn_id = atomic_inc_return(&tcpSesNextId);
        tcp_ses->noblockcnt = ctx->rootfs;
        tcp_ses->noblocksnd = ctx->noblocksnd || ctx->rootfs;
        tcp_ses->noautotune = ctx->noautotune;
        tcp_ses->tcp_nodelay = ctx->sockopt_tcp_nodelay;
        tcp_ses->rdma = ctx->rdma;
        tcp_ses->in_flight = 0;
        tcp_ses->max_in_flight = 0;
        tcp_ses->credits = 1;
        if (primary_server) {
                spin_lock(&cifs_tcp_ses_lock);
                ++primary_server->srv_count;
                spin_unlock(&cifs_tcp_ses_lock);
                tcp_ses->primary_server = primary_server;
        }
        init_waitqueue_head(&tcp_ses->response_q);
        init_waitqueue_head(&tcp_ses->request_q);
        INIT_LIST_HEAD(&tcp_ses->pending_mid_q);
        mutex_init(&tcp_ses->_srv_mutex);
        memcpy(tcp_ses->workstation_RFC1001_name,
                ctx->source_rfc1001_name, RFC1001_NAME_LEN_WITH_NULL);
        memcpy(tcp_ses->server_RFC1001_name,
                ctx->target_rfc1001_name, RFC1001_NAME_LEN_WITH_NULL);
        tcp_ses->rfc1001_sessinit = ctx->rfc1001_sessinit;
        tcp_ses->with_rfc1001 = false;
        tcp_ses->session_estab = false;
        tcp_ses->sequence_number = 0;
        tcp_ses->channel_sequence_num = 0; /* only tracked for primary channel */
        tcp_ses->reconnect_instance = 1;
        tcp_ses->lstrp = jiffies;
        tcp_ses->compression.requested = ctx->compress;
        spin_lock_init(&tcp_ses->req_lock);
        spin_lock_init(&tcp_ses->srv_lock);
        spin_lock_init(&tcp_ses->mid_queue_lock);
        spin_lock_init(&tcp_ses->mid_counter_lock);
        INIT_LIST_HEAD(&tcp_ses->tcp_ses_list);
        INIT_LIST_HEAD(&tcp_ses->smb_ses_list);
        INIT_DELAYED_WORK(&tcp_ses->echo, cifs_echo_request);
        INIT_DELAYED_WORK(&tcp_ses->reconnect, smb2_reconnect_server);
        mutex_init(&tcp_ses->reconnect_mutex);
        memcpy(&tcp_ses->srcaddr, &ctx->srcaddr,
               sizeof(tcp_ses->srcaddr));
        memcpy(&tcp_ses->dstaddr, &ctx->dstaddr,
                sizeof(tcp_ses->dstaddr));
        if (ctx->use_client_guid)
                memcpy(tcp_ses->client_guid, ctx->client_guid,
                       SMB2_CLIENT_GUID_SIZE);
        else
                generate_random_uuid(tcp_ses->client_guid);
        /*
         * at this point we are the only ones with the pointer
         * to the struct since the kernel thread not created yet
         * no need to spinlock this init of tcpStatus or srv_count
         */
        tcp_ses->tcpStatus = CifsNew;
        ++tcp_ses->srv_count;
        tcp_ses->echo_interval = ctx->echo_interval * HZ;

        if (tcp_ses->rdma) {
#ifndef CONFIG_CIFS_SMB_DIRECT
                cifs_dbg(VFS, "CONFIG_CIFS_SMB_DIRECT is not enabled\n");
                rc = -ENOENT;
                goto out_err_crypto_release;
#endif
                tcp_ses->smbd_conn = smbd_get_connection(
                        tcp_ses, (struct sockaddr *)&ctx->dstaddr);
                if (tcp_ses->smbd_conn) {
                        cifs_dbg(VFS, "RDMA transport established\n");
                        rc = 0;
                        goto smbd_connected;
                } else {
                        rc = -ENOENT;
                        goto out_err_crypto_release;
                }
        }
        rc = ip_connect(tcp_ses);
        if (rc < 0) {
                cifs_dbg(VFS, "Error connecting to socket. Aborting operation.\n");
                goto out_err_crypto_release;
        }
smbd_connected:
        /*
         * since we're in a cifs function already, we know that
         * this will succeed. No need for try_module_get().
         */
        __module_get(THIS_MODULE);
        tcp_ses->tsk = kthread_run(cifs_demultiplex_thread,
                                  tcp_ses, "cifsd");
        if (IS_ERR(tcp_ses->tsk)) {
                rc = PTR_ERR(tcp_ses->tsk);
                cifs_dbg(VFS, "error %d create cifsd thread\n", rc);
                module_put(THIS_MODULE);
                goto out_err_crypto_release;
        }
        tcp_ses->min_offload = ctx->min_offload;
        tcp_ses->retrans = ctx->retrans;
        /*
         * at this point we are the only ones with the pointer
         * to the struct since the kernel thread not created yet
         * no need to spinlock this update of tcpStatus
         */
        spin_lock(&tcp_ses->srv_lock);
        tcp_ses->tcpStatus = CifsNeedNegotiate;
        spin_unlock(&tcp_ses->srv_lock);

        if ((ctx->max_credits < 20) || (ctx->max_credits > 60000))
                tcp_ses->max_credits = SMB2_MAX_CREDITS_AVAILABLE;
        else
                tcp_ses->max_credits = ctx->max_credits;

        tcp_ses->nr_targets = 1;
        tcp_ses->ignore_signature = ctx->ignore_signature;
        /* thread spawned, put it on the list */
        spin_lock(&cifs_tcp_ses_lock);
        list_add(&tcp_ses->tcp_ses_list, &cifs_tcp_ses_list);
        spin_unlock(&cifs_tcp_ses_lock);

        /* queue echo request delayed work */
        queue_delayed_work(cifsiod_wq, &tcp_ses->echo, tcp_ses->echo_interval);

        return tcp_ses;

out_err_crypto_release:
        cifs_crypto_secmech_release(tcp_ses);

        put_net(cifs_net_ns(tcp_ses));

out_err:
        if (tcp_ses) {
                if (SERVER_IS_CHAN(tcp_ses))
                        cifs_put_tcp_session(tcp_ses->primary_server, false);
                kfree(tcp_ses->hostname);
                kfree(tcp_ses->leaf_fullpath);
                if (tcp_ses->ssocket)
                        sock_release(tcp_ses->ssocket);
                kfree(tcp_ses);
        }
        return ERR_PTR(rc);
}

/* this function must be called with ses_lock and chan_lock held */
static int match_session(struct cifs_ses *ses,
                         struct smb3_fs_context *ctx,
                         bool match_super)
{
        struct TCP_Server_Info *server = ses->server;
        enum securityEnum ctx_sec, ses_sec;

        if (!match_super && ctx->dfs_root_ses != ses->dfs_root_ses)
                return 0;

        /*
         * If an existing session is limited to less channels than
         * requested, it should not be reused
         */
        if (ses->chan_max < ctx->max_channels)
                return 0;

        ctx_sec = server->ops->select_sectype(server, ctx->sectype);
        ses_sec = server->ops->select_sectype(server, ses->sectype);

        if (ctx_sec != ses_sec)
                return 0;

        switch (ctx_sec) {
        case IAKerb:
        case Kerberos:
                if (!uid_eq(ctx->cred_uid, ses->cred_uid))
                        return 0;
                if (strncmp(ses->user_name ?: "",
                            ctx->username ?: "",
                            CIFS_MAX_USERNAME_LEN))
                        return 0;
                break;
        case NTLMv2:
        case RawNTLMSSP:
        default:
                /* NULL username means anonymous session */
                if (ses->user_name == NULL) {
                        if (!ctx->nullauth)
                                return 0;
                        break;
                }

                /* anything else takes username/password */
                if (strncmp(ses->user_name,
                            ctx->username ? ctx->username : "",
                            CIFS_MAX_USERNAME_LEN))
                        return 0;
                if ((ctx->username && strlen(ctx->username) != 0) &&
                    ses->password != NULL) {

                        /* New mount can only share sessions with an existing mount if:
                         * 1. Both password and password2 match, or
                         * 2. password2 of the old mount matches password of the new mount
                         *    and password of the old mount matches password2 of the new
                         *        mount
                         */
                        if (ses->password2 != NULL && ctx->password2 != NULL) {
                                if (!((strncmp(ses->password, ctx->password ?
                                        ctx->password : "", CIFS_MAX_PASSWORD_LEN) == 0 &&
                                        strncmp(ses->password2, ctx->password2,
                                        CIFS_MAX_PASSWORD_LEN) == 0) ||
                                        (strncmp(ses->password, ctx->password2,
                                        CIFS_MAX_PASSWORD_LEN) == 0 &&
                                        strncmp(ses->password2, ctx->password ?
                                        ctx->password : "", CIFS_MAX_PASSWORD_LEN) == 0)))
                                        return 0;

                        } else if ((ses->password2 == NULL && ctx->password2 != NULL) ||
                                (ses->password2 != NULL && ctx->password2 == NULL)) {
                                return 0;

                        } else {
                                if (strncmp(ses->password, ctx->password ?
                                        ctx->password : "", CIFS_MAX_PASSWORD_LEN))
                                        return 0;
                        }
                }
        }

        if (strcmp(ctx->local_nls->charset, ses->local_nls->charset))
                return 0;

        return 1;
}

/**
 * cifs_setup_ipc - helper to setup the IPC tcon for the session
 * @ses: smb session to issue the request on
 * @seal: if encryption is requested
 *
 * A new IPC connection is made and stored in the session
 * tcon_ipc. The IPC tcon has the same lifetime as the session.
 */
struct cifs_tcon *cifs_setup_ipc(struct cifs_ses *ses, bool seal)
{
        int rc = 0, xid;
        struct cifs_tcon *tcon;
        char unc[SERVER_NAME_LENGTH + sizeof("//x/IPC$")] = {0};
        struct TCP_Server_Info *server = ses->server;

        /*
         * If the mount request that resulted in the creation of the
         * session requires encryption, force IPC to be encrypted too.
         */
        if (seal && !(server->capabilities & SMB2_GLOBAL_CAP_ENCRYPTION)) {
                cifs_server_dbg(VFS, "IPC: server doesn't support encryption\n");
                return ERR_PTR(-EOPNOTSUPP);
        }

        /* no need to setup directory caching on IPC share, so pass in false */
        tcon = tcon_info_alloc(false, netfs_trace_tcon_ref_new_ipc);
        if (tcon == NULL)
                return ERR_PTR(-ENOMEM);

        spin_lock(&server->srv_lock);
        scnprintf(unc, sizeof(unc), "\\\\%s\\IPC$", server->hostname);
        spin_unlock(&server->srv_lock);

        xid = get_xid();
        tcon->ses = ses;
        tcon->ipc = true;
        tcon->seal = seal;
        rc = server->ops->tree_connect(xid, ses, unc, tcon, ses->local_nls);
        free_xid(xid);

        if (rc) {
                cifs_server_dbg(VFS | ONCE, "failed to connect to IPC (rc=%d)\n", rc);
                tconInfoFree(tcon, netfs_trace_tcon_ref_free_ipc_fail);
                return ERR_PTR(rc);
        }

        cifs_dbg(FYI, "IPC tcon rc=%d ipc tid=0x%x\n", rc, tcon->tid);

        spin_lock(&tcon->tc_lock);
        tcon->status = TID_GOOD;
        spin_unlock(&tcon->tc_lock);
        return tcon;
}

static struct cifs_ses *
cifs_find_smb_ses(struct TCP_Server_Info *server, struct smb3_fs_context *ctx)
{
        struct cifs_ses *ses, *ret = NULL;

        spin_lock(&cifs_tcp_ses_lock);
        list_for_each_entry(ses, &server->smb_ses_list, smb_ses_list) {
                spin_lock(&ses->ses_lock);
                if (ses->ses_status == SES_EXITING) {
                        spin_unlock(&ses->ses_lock);
                        continue;
                }
                spin_lock(&ses->chan_lock);
                if (match_session(ses, ctx, false)) {
                        spin_unlock(&ses->chan_lock);
                        spin_unlock(&ses->ses_lock);
                        ret = ses;
                        break;
                }
                spin_unlock(&ses->chan_lock);
                spin_unlock(&ses->ses_lock);
        }
        if (ret)
                cifs_smb_ses_inc_refcount(ret);
        spin_unlock(&cifs_tcp_ses_lock);
        return ret;
}

void __cifs_put_smb_ses(struct cifs_ses *ses)
{
        struct TCP_Server_Info *server = ses->server;
        struct cifs_tcon *tcon;
        unsigned int xid;
        size_t i;
        bool do_logoff;
        int rc;

        spin_lock(&cifs_tcp_ses_lock);
        spin_lock(&ses->ses_lock);
        cifs_dbg(FYI, "%s: id=0x%llx ses_count=%d ses_status=%u ipc=%s\n",
                 __func__, ses->Suid, ses->ses_count, ses->ses_status,
                 ses->tcon_ipc ? ses->tcon_ipc->tree_name : "none");
        if (ses->ses_status == SES_EXITING || --ses->ses_count > 0) {
                spin_unlock(&ses->ses_lock);
                spin_unlock(&cifs_tcp_ses_lock);
                return;
        }
        /* ses_count can never go negative */
        WARN_ON(ses->ses_count < 0);

        spin_lock(&ses->chan_lock);
        cifs_chan_clear_need_reconnect(ses, server);
        spin_unlock(&ses->chan_lock);

        do_logoff = ses->ses_status == SES_GOOD && server->ops->logoff;
        ses->ses_status = SES_EXITING;
        tcon = ses->tcon_ipc;
        ses->tcon_ipc = NULL;
        spin_unlock(&ses->ses_lock);
        spin_unlock(&cifs_tcp_ses_lock);

        /*
         * On session close, the IPC is closed and the server must release all
         * tcons of the session.  No need to send a tree disconnect here.
         *
         * Besides, it will make the server to not close durable and resilient
         * files on session close, as specified in MS-SMB2 3.3.5.6 Receiving an
         * SMB2 LOGOFF Request.
         */
        tconInfoFree(tcon, netfs_trace_tcon_ref_free_ipc);
        if (do_logoff) {
                xid = get_xid();
                rc = server->ops->logoff(xid, ses);
                cifs_server_dbg(FYI, "%s: Session Logoff: rc=%d\n",
                                __func__, rc);
                _free_xid(xid);
        }

        spin_lock(&cifs_tcp_ses_lock);
        list_del_init(&ses->smb_ses_list);
        spin_unlock(&cifs_tcp_ses_lock);

        /* close any extra channels */
        for (i = 1; i < ses->chan_count; i++) {
                if (ses->chans[i].iface) {
                        kref_put(&ses->chans[i].iface->refcount, release_iface);
                        ses->chans[i].iface = NULL;
                }
                cifs_put_tcp_session(ses->chans[i].server, 0);
                ses->chans[i].server = NULL;
        }

        /* we now account for primary channel in iface->refcount */
        if (ses->chans[0].iface) {
                kref_put(&ses->chans[0].iface->refcount, release_iface);
                ses->chans[0].server = NULL;
        }

        sesInfoFree(ses);
        cifs_put_tcp_session(server, 0);
}

#ifdef CONFIG_KEYS

/* Populate username and pw fields from keyring if possible */
static int
cifs_set_cifscreds(struct smb3_fs_context *ctx, struct cifs_ses *ses)
{
        int rc = 0;
        int is_domain = 0;
        const char *delim, *payload;
        size_t desc_sz;
        char *desc;
        ssize_t len;
        struct key *key;
        struct TCP_Server_Info *server = ses->server;
        struct sockaddr_in *sa;
        struct sockaddr_in6 *sa6;
        const struct user_key_payload *upayload;

        /* "cifs:a:" and "cifs:d:" are the same length; +1 for NUL terminator */
        desc_sz = strlen("cifs:a:") + CIFS_MAX_DOMAINNAME_LEN + 1;
        desc = kmalloc(desc_sz, GFP_KERNEL);
        if (!desc)
                return -ENOMEM;

        /* try to find an address key first */
        switch (server->dstaddr.ss_family) {
        case AF_INET:
                sa = (struct sockaddr_in *)&server->dstaddr;
                snprintf(desc, desc_sz, "cifs:a:%pI4", &sa->sin_addr.s_addr);
                break;
        case AF_INET6:
                sa6 = (struct sockaddr_in6 *)&server->dstaddr;
                snprintf(desc, desc_sz, "cifs:a:%pI6c", &sa6->sin6_addr.s6_addr);
                break;
        default:
                cifs_dbg(FYI, "Bad ss_family (%hu)\n",
                         server->dstaddr.ss_family);
                rc = -EINVAL;
                goto out_err;
        }

        cifs_dbg(FYI, "%s: desc=%s\n", __func__, desc);
        key = request_key(&key_type_logon, desc, "");
        if (IS_ERR(key)) {
                if (!ses->domainName) {
                        cifs_dbg(FYI, "domainName is NULL\n");
                        rc = PTR_ERR(key);
                        goto out_err;
                }

                /* didn't work, try to find a domain key */
                snprintf(desc, desc_sz, "cifs:d:%s", ses->domainName);
                cifs_dbg(FYI, "%s: desc=%s\n", __func__, desc);
                key = request_key(&key_type_logon, desc, "");
                if (IS_ERR(key)) {
                        rc = PTR_ERR(key);
                        goto out_err;
                }
                is_domain = 1;
        }

        down_read(&key->sem);
        upayload = user_key_payload_locked(key);
        if (IS_ERR_OR_NULL(upayload)) {
                rc = upayload ? PTR_ERR(upayload) : -EINVAL;
                goto out_key_put;
        }

        /* find first : in payload */
        payload = upayload->data;
        delim = strnchr(payload, upayload->datalen, ':');
        if (!delim) {
                cifs_dbg(FYI, "Unable to find ':' in payload (datalen=%d)\n",
                         upayload->datalen);
                rc = -EINVAL;
                goto out_key_put;
        }

        len = delim - payload;
        if (len > CIFS_MAX_USERNAME_LEN || len <= 0) {
                cifs_dbg(FYI, "Bad value from username search (len=%zd)\n",
                         len);
                rc = -EINVAL;
                goto out_key_put;
        }

        ctx->username = kstrndup(payload, len, GFP_KERNEL);
        if (!ctx->username) {
                cifs_dbg(FYI, "Unable to allocate %zd bytes for username\n",
                         len);
                rc = -ENOMEM;
                goto out_key_put;
        }
        cifs_dbg(FYI, "%s: username=%s\n", __func__, ctx->username);

        len = key->datalen - (len + 1);
        if (len > CIFS_MAX_PASSWORD_LEN || len <= 0) {
                cifs_dbg(FYI, "Bad len for password search (len=%zd)\n", len);
                rc = -EINVAL;
                kfree(ctx->username);
                ctx->username = NULL;
                goto out_key_put;
        }

        ++delim;
        /* BB consider adding support for password2 (Key Rotation) for multiuser in future */
        ctx->password = kstrndup(delim, len, GFP_KERNEL);
        if (!ctx->password) {
                cifs_dbg(FYI, "Unable to allocate %zd bytes for password\n",
                         len);
                rc = -ENOMEM;
                kfree(ctx->username);
                ctx->username = NULL;
                goto out_key_put;
        }

        /*
         * If we have a domain key then we must set the domainName in the
         * for the request.
         */
        if (is_domain && ses->domainName) {
                ctx->domainname = kstrdup(ses->domainName, GFP_KERNEL);
                if (!ctx->domainname) {
                        cifs_dbg(FYI, "Unable to allocate %zd bytes for domain\n",
                                 len);
                        rc = -ENOMEM;
                        kfree(ctx->username);
                        ctx->username = NULL;
                        kfree_sensitive(ctx->password);
                        /* no need to free ctx->password2 since not allocated in this path */
                        ctx->password = NULL;
                        goto out_key_put;
                }
        }

        strscpy(ctx->workstation_name, ses->workstation_name, sizeof(ctx->workstation_name));

out_key_put:
        up_read(&key->sem);
        key_put(key);
out_err:
        kfree(desc);
        cifs_dbg(FYI, "%s: returning %d\n", __func__, rc);
        return rc;
}
#else /* ! CONFIG_KEYS */
static inline int
cifs_set_cifscreds(struct smb3_fs_context *ctx __maybe_unused,
                   struct cifs_ses *ses __maybe_unused)
{
        return -ENOSYS;
}
#endif /* CONFIG_KEYS */

/**
 * cifs_get_smb_ses - get a session matching @ctx data from @server
 * @server: server to setup the session to
 * @ctx: superblock configuration context to use to setup the session
 *
 * This function assumes it is being called from cifs_mount() where we
 * already got a server reference (server refcount +1). See
 * cifs_get_tcon() for refcount explanations.
 */
struct cifs_ses *
cifs_get_smb_ses(struct TCP_Server_Info *server, struct smb3_fs_context *ctx)
{
        struct sockaddr_in6 *addr6 = (struct sockaddr_in6 *)&server->dstaddr;
        struct sockaddr_in *addr = (struct sockaddr_in *)&server->dstaddr;
        struct cifs_tcon *ipc;
        struct cifs_ses *ses;
        unsigned int xid;
        int retries = 0;
        size_t len;
        int rc = 0;

        xid = get_xid();

        ses = cifs_find_smb_ses(server, ctx);
        if (ses) {
                cifs_dbg(FYI, "Existing smb sess found (status=%d)\n",
                         ses->ses_status);

                spin_lock(&ses->chan_lock);
                if (cifs_chan_needs_reconnect(ses, server)) {
                        spin_unlock(&ses->chan_lock);
                        cifs_dbg(FYI, "Session needs reconnect\n");

                        mutex_lock(&ses->session_mutex);

retry_old_session:
                        rc = cifs_negotiate_protocol(xid, ses, server);
                        if (rc) {
                                mutex_unlock(&ses->session_mutex);
                                /* problem -- put our ses reference */
                                cifs_put_smb_ses(ses);
                                free_xid(xid);
                                return ERR_PTR(rc);
                        }

                        rc = cifs_setup_session(xid, ses, server,
                                                ctx->local_nls);
                        if (rc) {
                                if (((rc == -EACCES) || (rc == -EKEYEXPIRED) ||
                                        (rc == -EKEYREVOKED)) && !retries && ses->password2) {
                                        retries++;
                                        cifs_dbg(FYI, "Session reconnect failed, retrying with alternate password\n");
                                        swap(ses->password, ses->password2);
                                        goto retry_old_session;
                                }
                                mutex_unlock(&ses->session_mutex);
                                /* problem -- put our reference */
                                cifs_put_smb_ses(ses);
                                free_xid(xid);
                                return ERR_PTR(rc);
                        }
                        mutex_unlock(&ses->session_mutex);

                        spin_lock(&ses->chan_lock);
                }
                spin_unlock(&ses->chan_lock);

                /* existing SMB ses has a server reference already */
                cifs_put_tcp_session(server, 0);
                free_xid(xid);
                return ses;
        }

        rc = -ENOMEM;

        cifs_dbg(FYI, "Existing smb sess not found\n");
        ses = sesInfoAlloc();
        if (ses == NULL)
                goto get_ses_fail;

        /* new SMB session uses our server ref */
        ses->server = server;
        if (server->dstaddr.ss_family == AF_INET6)
                sprintf(ses->ip_addr, "%pI6", &addr6->sin6_addr);
        else
                sprintf(ses->ip_addr, "%pI4", &addr->sin_addr);

        if (ctx->username) {
                ses->user_name = kstrdup(ctx->username, GFP_KERNEL);
                if (!ses->user_name)
                        goto get_ses_fail;
        }

        /* ctx->password freed at unmount */
        if (ctx->password) {
                ses->password = kstrdup(ctx->password, GFP_KERNEL);
                if (!ses->password)
                        goto get_ses_fail;
        }
        /* ctx->password freed at unmount */
        if (ctx->password2) {
                ses->password2 = kstrdup(ctx->password2, GFP_KERNEL);
                if (!ses->password2)
                        goto get_ses_fail;
        }
        if (ctx->domainname) {
                ses->domainName = kstrdup(ctx->domainname, GFP_KERNEL);
                if (!ses->domainName)
                        goto get_ses_fail;

                len = strnlen(ctx->domainname, CIFS_MAX_DOMAINNAME_LEN);
                if (!cifs_netbios_name(ctx->domainname, len)) {
                        ses->dns_dom = kstrndup(ctx->domainname,
                                                len, GFP_KERNEL);
                        if (!ses->dns_dom)
                                goto get_ses_fail;
                }
        }

        strscpy(ses->workstation_name, ctx->workstation_name, sizeof(ses->workstation_name));

        if (ctx->domainauto)
                ses->domainAuto = ctx->domainauto;
        ses->cred_uid = ctx->cred_uid;
        ses->linux_uid = ctx->linux_uid;

        ses->unicode = ctx->unicode;
        ses->sectype = ctx->sectype;
        ses->sign = ctx->sign;

        /*
         *Explicitly marking upcall_target mount option for easier handling
         * by cifs_spnego.c and eventually cifs.upcall.c
         */

        switch (ctx->upcall_target) {
        case UPTARGET_UNSPECIFIED: /* default to app */
        case UPTARGET_APP:
                ses->upcall_target = UPTARGET_APP;
                break;
        case UPTARGET_MOUNT:
                ses->upcall_target = UPTARGET_MOUNT;
                break;
        default:
                // should never happen
                ses->upcall_target = UPTARGET_APP;
                break;
        }

        ses->local_nls = load_nls(ctx->local_nls->charset);

        /* add server as first channel */
        spin_lock(&ses->chan_lock);
        ses->chans[0].server = server;
        ses->chan_count = 1;
        ses->chan_max = ctx->multichannel ? ctx->max_channels:1;
        ses->chans_need_reconnect = 1;
        spin_unlock(&ses->chan_lock);

retry_new_session:
        mutex_lock(&ses->session_mutex);
        rc = cifs_negotiate_protocol(xid, ses, server);
        if (!rc)
                rc = cifs_setup_session(xid, ses, server, ctx->local_nls);
        mutex_unlock(&ses->session_mutex);

        /* each channel uses a different signing key */
        spin_lock(&ses->chan_lock);
        memcpy(ses->chans[0].signkey, ses->smb3signingkey,
               sizeof(ses->smb3signingkey));
        spin_unlock(&ses->chan_lock);

        if (rc) {
                if (((rc == -EACCES) || (rc == -EKEYEXPIRED) ||
                        (rc == -EKEYREVOKED)) && !retries && ses->password2) {
                        retries++;
                        cifs_dbg(FYI, "Session setup failed, retrying with alternate password\n");
                        swap(ses->password, ses->password2);
                        goto retry_new_session;
                } else
                        goto get_ses_fail;
        }

        /*
         * success, put it on the list and add it as first channel
         * note: the session becomes active soon after this. So you'll
         * need to lock before changing something in the session.
         */
        spin_lock(&cifs_tcp_ses_lock);
        ses->dfs_root_ses = ctx->dfs_root_ses;
        list_add(&ses->smb_ses_list, &server->smb_ses_list);
        spin_unlock(&cifs_tcp_ses_lock);

        ipc = cifs_setup_ipc(ses, ctx->seal);
        spin_lock(&cifs_tcp_ses_lock);
        spin_lock(&ses->ses_lock);
        ses->tcon_ipc = !IS_ERR(ipc) ? ipc : NULL;
        spin_unlock(&ses->ses_lock);
        spin_unlock(&cifs_tcp_ses_lock);

        free_xid(xid);

        return ses;

get_ses_fail:
        sesInfoFree(ses);
        free_xid(xid);
        return ERR_PTR(rc);
}

/* this function must be called with tc_lock held */
static int match_tcon(struct cifs_tcon *tcon, struct smb3_fs_context *ctx)
{
        struct TCP_Server_Info *server = tcon->ses->server;

        if (tcon->status == TID_EXITING)
                return 0;

        if (tcon->origin_fullpath) {
                if (!ctx->source ||
                    !dfs_src_pathname_equal(ctx->source,
                                            tcon->origin_fullpath))
                        return 0;
        } else if (!server->leaf_fullpath &&
                   strncmp(tcon->tree_name, ctx->UNC, MAX_TREE_SIZE)) {
                return 0;
        }
        if (tcon->seal != ctx->seal)
                return 0;
        if (tcon->snapshot_time != ctx->snapshot_time)
                return 0;
        if (tcon->handle_timeout != ctx->handle_timeout)
                return 0;
        if (tcon->no_lease != ctx->no_lease)
                return 0;
        if (tcon->nodelete != ctx->nodelete)
                return 0;
        if (tcon->posix_extensions != ctx->linux_ext)
                return 0;
        return 1;
}

static struct cifs_tcon *
cifs_find_tcon(struct cifs_ses *ses, struct smb3_fs_context *ctx)
{
        struct cifs_tcon *tcon;

        spin_lock(&cifs_tcp_ses_lock);
        list_for_each_entry(tcon, &ses->tcon_list, tcon_list) {
                spin_lock(&tcon->tc_lock);
                if (!match_tcon(tcon, ctx)) {
                        spin_unlock(&tcon->tc_lock);
                        continue;
                }
                ++tcon->tc_count;
                trace_smb3_tcon_ref(tcon->debug_id, tcon->tc_count,
                                    netfs_trace_tcon_ref_get_find);
                spin_unlock(&tcon->tc_lock);
                spin_unlock(&cifs_tcp_ses_lock);
                return tcon;
        }
        spin_unlock(&cifs_tcp_ses_lock);
        return NULL;
}

void
cifs_put_tcon(struct cifs_tcon *tcon, enum smb3_tcon_ref_trace trace)
{
        unsigned int xid;
        struct cifs_ses *ses;
        LIST_HEAD(ses_list);

        /*
         * IPC tcon share the lifetime of their session and are
         * destroyed in the session put function
         */
        if (tcon == NULL || tcon->ipc)
                return;

        ses = tcon->ses;
        cifs_dbg(FYI, "%s: tc_count=%d\n", __func__, tcon->tc_count);
        spin_lock(&cifs_tcp_ses_lock);
        spin_lock(&tcon->tc_lock);
        trace_smb3_tcon_ref(tcon->debug_id, tcon->tc_count - 1, trace);
        if (--tcon->tc_count > 0) {
                spin_unlock(&tcon->tc_lock);
                spin_unlock(&cifs_tcp_ses_lock);
                return;
        }

        /* tc_count can never go negative */
        WARN_ON(tcon->tc_count < 0);

        list_del_init(&tcon->tcon_list);
        tcon->status = TID_EXITING;
        spin_unlock(&tcon->tc_lock);
        spin_unlock(&cifs_tcp_ses_lock);

        /* cancel polling of interfaces */
        cancel_delayed_work_sync(&tcon->query_interfaces);
#ifdef CONFIG_CIFS_DFS_UPCALL
        cancel_delayed_work_sync(&tcon->dfs_cache_work);
        list_replace_init(&tcon->dfs_ses_list, &ses_list);
#endif

        if (tcon->use_witness) {
                int rc;

                rc = cifs_swn_unregister(tcon);
                if (rc < 0) {
                        cifs_dbg(VFS, "%s: Failed to unregister for witness notifications: %d\n",
                                        __func__, rc);
                }
        }

        xid = get_xid();
        if (ses->server->ops->tree_disconnect)
                ses->server->ops->tree_disconnect(xid, tcon);
        _free_xid(xid);

        cifs_fscache_release_super_cookie(tcon);
        tconInfoFree(tcon, netfs_trace_tcon_ref_free);
        cifs_put_smb_ses(ses);
#ifdef CONFIG_CIFS_DFS_UPCALL
        dfs_put_root_smb_sessions(&ses_list);
#endif
}

/**
 * cifs_get_tcon - get a tcon matching @ctx data from @ses
 * @ses: smb session to issue the request on
 * @ctx: the superblock configuration context to use for building the
 *
 * - tcon refcount is the number of mount points using the tcon.
 * - ses refcount is the number of tcon using the session.
 *
 * 1. This function assumes it is being called from cifs_mount() where
 *    we already got a session reference (ses refcount +1).
 *
 * 2. Since we're in the context of adding a mount point, the end
 *    result should be either:
 *
 * a) a new tcon already allocated with refcount=1 (1 mount point) and
 *    its session refcount incremented (1 new tcon). This +1 was
 *    already done in (1).
 *
 * b) an existing tcon with refcount+1 (add a mount point to it) and
 *    identical ses refcount (no new tcon). Because of (1) we need to
 *    decrement the ses refcount.
 */
static struct cifs_tcon *
cifs_get_tcon(struct cifs_ses *ses, struct smb3_fs_context *ctx)
{
        struct cifs_tcon *tcon;
        bool nohandlecache;
        int rc, xid;

        tcon = cifs_find_tcon(ses, ctx);
        if (tcon) {
                /*
                 * tcon has refcount already incremented but we need to
                 * decrement extra ses reference gotten by caller (case b)
                 */
                cifs_dbg(FYI, "Found match on UNC path\n");
                cifs_put_smb_ses(ses);
                return tcon;
        }

        if (!ses->server->ops->tree_connect) {
                rc = -ENOSYS;
                goto out_fail;
        }

        if (ses->server->dialect >= SMB20_PROT_ID &&
            (ses->server->capabilities & SMB2_GLOBAL_CAP_DIRECTORY_LEASING))
                nohandlecache = ctx->nohandlecache || !dir_cache_timeout;
        else
                nohandlecache = true;
        tcon = tcon_info_alloc(!nohandlecache, netfs_trace_tcon_ref_new);
        if (tcon == NULL) {
                rc = -ENOMEM;
                goto out_fail;
        }
        tcon->nohandlecache = nohandlecache;

        if (ctx->snapshot_time) {
                if (ses->server->vals->protocol_id == 0) {
                        cifs_dbg(VFS,
                             "Use SMB2 or later for snapshot mount option\n");
                        rc = -EOPNOTSUPP;
                        goto out_fail;
                } else
                        tcon->snapshot_time = ctx->snapshot_time;
        }

        if (ctx->handle_timeout) {
                if (ses->server->vals->protocol_id == 0) {
                        cifs_dbg(VFS,
                             "Use SMB2.1 or later for handle timeout option\n");
                        rc = -EOPNOTSUPP;
                        goto out_fail;
                } else
                        tcon->handle_timeout = ctx->handle_timeout;
        }

        tcon->ses = ses;
        if (ctx->password) {
                tcon->password = kstrdup(ctx->password, GFP_KERNEL);
                if (!tcon->password) {
                        rc = -ENOMEM;
                        goto out_fail;
                }
        }

        if (ctx->seal) {
                if (ses->server->vals->protocol_id == 0) {
                        cifs_dbg(VFS,
                                 "SMB3 or later required for encryption\n");
                        rc = -EOPNOTSUPP;
                        goto out_fail;
                } else if (tcon->ses->server->capabilities &
                                        SMB2_GLOBAL_CAP_ENCRYPTION)
                        tcon->seal = true;
                else {
                        cifs_dbg(VFS, "Encryption is not supported on share\n");
                        rc = -EOPNOTSUPP;
                        goto out_fail;
                }
        }

        if (ctx->linux_ext) {
                if (ses->server->posix_ext_supported) {
                        tcon->posix_extensions = true;
                        pr_warn_once("SMB3.11 POSIX Extensions are experimental\n");
                } else if ((ses->server->vals->protocol_id == SMB311_PROT_ID) ||
                    (strcmp(ses->server->vals->version_string,
                     SMB3ANY_VERSION_STRING) == 0) ||
                    (strcmp(ses->server->vals->version_string,
                     SMBDEFAULT_VERSION_STRING) == 0)) {
                        cifs_dbg(VFS, "Server does not support mounting with posix SMB3.11 extensions\n");
                        rc = -EOPNOTSUPP;
                        goto out_fail;
                } else if (ses->server->vals->protocol_id == SMB10_PROT_ID)
                        if (cap_unix(ses))
                                cifs_dbg(FYI, "Unix Extensions requested on SMB1 mount\n");
                        else {
                                cifs_dbg(VFS, "SMB1 Unix Extensions not supported by server\n");
                                rc = -EOPNOTSUPP;
                                goto out_fail;
                } else {
                        cifs_dbg(VFS,
                                "Check vers= mount option. SMB3.11 disabled but required for POSIX extensions\n");
                        rc = -EOPNOTSUPP;
                        goto out_fail;
                }
        }

        xid = get_xid();
        rc = ses->server->ops->tree_connect(xid, ses, ctx->UNC, tcon,
                                            ctx->local_nls);
        free_xid(xid);
        cifs_dbg(FYI, "Tcon rc = %d\n", rc);
        if (rc)
                goto out_fail;

        tcon->use_persistent = false;
        /* check if SMB2 or later, CIFS does not support persistent handles */
        if (ctx->persistent) {
                if (ses->server->vals->protocol_id == 0) {
                        cifs_dbg(VFS,
                             "SMB3 or later required for persistent handles\n");
                        rc = -EOPNOTSUPP;
                        goto out_fail;
                } else if (ses->server->capabilities &
                           SMB2_GLOBAL_CAP_PERSISTENT_HANDLES)
                        tcon->use_persistent = true;
                else /* persistent handles requested but not supported */ {
                        cifs_dbg(VFS,
                                "Persistent handles not supported on share\n");
                        rc = -EOPNOTSUPP;
                        goto out_fail;
                }
        } else if ((tcon->capabilities & SMB2_SHARE_CAP_CONTINUOUS_AVAILABILITY)
             && (ses->server->capabilities & SMB2_GLOBAL_CAP_PERSISTENT_HANDLES)
             && (ctx->nopersistent == false)) {
                cifs_dbg(FYI, "enabling persistent handles\n");
                tcon->use_persistent = true;
        } else if (ctx->resilient) {
                if (ses->server->vals->protocol_id == 0) {
                        cifs_dbg(VFS,
                             "SMB2.1 or later required for resilient handles\n");
                        rc = -EOPNOTSUPP;
                        goto out_fail;
                }
                tcon->use_resilient = true;
        }

        tcon->use_witness = false;
        if (IS_ENABLED(CONFIG_CIFS_SWN_UPCALL) && ctx->witness) {
                if (ses->server->vals->protocol_id >= SMB30_PROT_ID) {
                        if (tcon->capabilities & SMB2_SHARE_CAP_CLUSTER) {
                                /*
                                 * Set witness in use flag in first place
                                 * to retry registration in the echo task
                                 */
                                tcon->use_witness = true;
                                /* And try to register immediately */
                                rc = cifs_swn_register(tcon);
                                if (rc < 0) {
                                        cifs_dbg(VFS, "Failed to register for witness notifications: %d\n", rc);
                                        goto out_fail;
                                }
                        } else {
                                /* TODO: try to extend for non-cluster uses (eg multichannel) */
                                cifs_dbg(VFS, "witness requested on mount but no CLUSTER capability on share\n");
                                rc = -EOPNOTSUPP;
                                goto out_fail;
                        }
                } else {
                        cifs_dbg(VFS, "SMB3 or later required for witness option\n");
                        rc = -EOPNOTSUPP;
                        goto out_fail;
                }
        }

        /* If the user really knows what they are doing they can override */
        if (tcon->share_flags & SMB2_SHAREFLAG_NO_CACHING) {
                if (ctx->cache_ro)
                        cifs_dbg(VFS, "cache=ro requested on mount but NO_CACHING flag set on share\n");
                else if (ctx->cache_rw)
                        cifs_dbg(VFS, "cache=singleclient requested on mount but NO_CACHING flag set on share\n");
        }

        if (ctx->no_lease) {
                if (ses->server->vals->protocol_id == 0) {
                        cifs_dbg(VFS,
                                "SMB2 or later required for nolease option\n");
                        rc = -EOPNOTSUPP;
                        goto out_fail;
                } else
                        tcon->no_lease = ctx->no_lease;
        }

        /*
         * We can have only one retry value for a connection to a share so for
         * resources mounted more than once to the same server share the last
         * value passed in for the retry flag is used.
         */
        tcon->retry = ctx->retry;
        tcon->nocase = ctx->nocase;
        tcon->broken_sparse_sup = ctx->no_sparse;
        tcon->max_cached_dirs = ctx->max_cached_dirs;
        tcon->nodelete = ctx->nodelete;
        tcon->local_lease = ctx->local_lease;
        tcon->status = TID_GOOD;

        if (ses->server->dialect >= SMB30_PROT_ID &&
            (ses->server->capabilities & SMB2_GLOBAL_CAP_MULTI_CHANNEL)) {
                /* schedule query interfaces poll */
                queue_delayed_work(cifsiod_wq, &tcon->query_interfaces,
                                   (SMB_INTERFACE_POLL_INTERVAL * HZ));
        }
        spin_lock(&cifs_tcp_ses_lock);
        list_add(&tcon->tcon_list, &ses->tcon_list);
        spin_unlock(&cifs_tcp_ses_lock);

        return tcon;

out_fail:
        tconInfoFree(tcon, netfs_trace_tcon_ref_free_fail);
        return ERR_PTR(rc);
}

void
cifs_put_tlink(struct tcon_link *tlink)
{
        if (!tlink || IS_ERR(tlink))
                return;

        if (!atomic_dec_and_test(&tlink->tl_count) ||
            test_bit(TCON_LINK_IN_TREE, &tlink->tl_flags)) {
                tlink->tl_time = jiffies;
                return;
        }

        if (!IS_ERR(tlink_tcon(tlink)))
                cifs_put_tcon(tlink_tcon(tlink), netfs_trace_tcon_ref_put_tlink);
        kfree(tlink);
}

static int
compare_mount_options(struct super_block *sb, struct cifs_mnt_data *mnt_data)
{
        struct cifs_sb_info *old = CIFS_SB(sb);
        struct cifs_sb_info *new = mnt_data->cifs_sb;
        unsigned int oldflags = cifs_sb_flags(old) & CIFS_MOUNT_MASK;
        unsigned int newflags = cifs_sb_flags(new) & CIFS_MOUNT_MASK;

        if ((sb->s_flags & CIFS_MS_MASK) != (mnt_data->flags & CIFS_MS_MASK))
                return 0;

        if (old->mnt_cifs_serverino_autodisabled)
                newflags &= ~CIFS_MOUNT_SERVER_INUM;

        if (oldflags != newflags)
                return 0;

        /*
         * We want to share sb only if we don't specify an r/wsize or
         * specified r/wsize is greater than or equal to existing one.
         */
        if (new->ctx->wsize && new->ctx->wsize < old->ctx->wsize)
                return 0;

        if (new->ctx->rsize && new->ctx->rsize < old->ctx->rsize)
                return 0;

        if (!uid_eq(old->ctx->linux_uid, new->ctx->linux_uid) ||
            !gid_eq(old->ctx->linux_gid, new->ctx->linux_gid))
                return 0;

        if (old->ctx->file_mode != new->ctx->file_mode ||
            old->ctx->dir_mode != new->ctx->dir_mode)
                return 0;

        if (strcmp(old->local_nls->charset, new->local_nls->charset))
                return 0;

        if (old->ctx->acregmax != new->ctx->acregmax)
                return 0;
        if (old->ctx->acdirmax != new->ctx->acdirmax)
                return 0;
        if (old->ctx->closetimeo != new->ctx->closetimeo)
                return 0;
        if (old->ctx->reparse_type != new->ctx->reparse_type)
                return 0;
        if (old->ctx->nonativesocket != new->ctx->nonativesocket)
                return 0;
        if (old->ctx->symlink_type != new->ctx->symlink_type)
                return 0;

        return 1;
}

static int match_prepath(struct super_block *sb,
                         struct cifs_tcon *tcon,
                         struct cifs_mnt_data *mnt_data)
{
        struct smb3_fs_context *ctx = mnt_data->ctx;
        struct cifs_sb_info *old = CIFS_SB(sb);
        struct cifs_sb_info *new = mnt_data->cifs_sb;
        bool old_set = (cifs_sb_flags(old) & CIFS_MOUNT_USE_PREFIX_PATH) &&
                old->prepath;
        bool new_set = (cifs_sb_flags(new) & CIFS_MOUNT_USE_PREFIX_PATH) &&
                new->prepath;

        if (tcon->origin_fullpath &&
            dfs_src_pathname_equal(tcon->origin_fullpath, ctx->source))
                return 1;

        if (old_set && new_set && !strcmp(new->prepath, old->prepath))
                return 1;
        else if (!old_set && !new_set)
                return 1;

        return 0;
}

int
cifs_match_super(struct super_block *sb, void *data)
{
        struct cifs_mnt_data *mnt_data = data;
        struct smb3_fs_context *ctx;
        struct cifs_sb_info *cifs_sb;
        struct TCP_Server_Info *tcp_srv;
        struct cifs_ses *ses;
        struct cifs_tcon *tcon;
        struct tcon_link *tlink;
        int rc = 0;

        spin_lock(&cifs_tcp_ses_lock);
        cifs_sb = CIFS_SB(sb);

        /* We do not want to use a superblock that has been shutdown */
        if (cifs_forced_shutdown(cifs_sb)) {
                spin_unlock(&cifs_tcp_ses_lock);
                return 0;
        }

        tlink = cifs_get_tlink(cifs_sb_master_tlink(cifs_sb));
        if (IS_ERR_OR_NULL(tlink)) {
                pr_warn_once("%s: skip super matching due to bad tlink(%p)\n",
                             __func__, tlink);
                spin_unlock(&cifs_tcp_ses_lock);
                return 0;
        }
        tcon = tlink_tcon(tlink);
        ses = tcon->ses;
        tcp_srv = ses->server;

        ctx = mnt_data->ctx;

        spin_lock(&tcp_srv->srv_lock);
        spin_lock(&ses->ses_lock);
        spin_lock(&ses->chan_lock);
        spin_lock(&tcon->tc_lock);
        if (!match_server(tcp_srv, ctx, true) ||
            !match_session(ses, ctx, true) ||
            !match_tcon(tcon, ctx) ||
            !match_prepath(sb, tcon, mnt_data)) {
                rc = 0;
                goto out;
        }

        rc = compare_mount_options(sb, mnt_data);
out:
        spin_unlock(&tcon->tc_lock);
        spin_unlock(&ses->chan_lock);
        spin_unlock(&ses->ses_lock);
        spin_unlock(&tcp_srv->srv_lock);

        spin_unlock(&cifs_tcp_ses_lock);
        cifs_put_tlink(tlink);
        return rc;
}

#ifdef CONFIG_DEBUG_LOCK_ALLOC
static struct lock_class_key cifs_key[2];
static struct lock_class_key cifs_slock_key[2];

static inline void
cifs_reclassify_socket4(struct socket *sock)
{
        struct sock *sk = sock->sk;

        BUG_ON(!sock_allow_reclassification(sk));
        sock_lock_init_class_and_name(sk, "slock-AF_INET-CIFS",
                &cifs_slock_key[0], "sk_lock-AF_INET-CIFS", &cifs_key[0]);
}

static inline void
cifs_reclassify_socket6(struct socket *sock)
{
        struct sock *sk = sock->sk;

        BUG_ON(!sock_allow_reclassification(sk));
        sock_lock_init_class_and_name(sk, "slock-AF_INET6-CIFS",
                &cifs_slock_key[1], "sk_lock-AF_INET6-CIFS", &cifs_key[1]);
}
#else
static inline void
cifs_reclassify_socket4(struct socket *sock)
{
}

static inline void
cifs_reclassify_socket6(struct socket *sock)
{
}
#endif

/* See RFC1001 section 14 on representation of Netbios names */
static void rfc1002mangle(char *target, char *source, unsigned int length)
{
        unsigned int i, j;

        for (i = 0, j = 0; i < (length); i++) {
                /* mask a nibble at a time and encode */
                target[j] = 'A' + (0x0F & (source[i] >> 4));
                target[j+1] = 'A' + (0x0F & source[i]);
                j += 2;
        }

}

static int
bind_socket(struct TCP_Server_Info *server)
{
        int rc = 0;

        if (server->srcaddr.ss_family != AF_UNSPEC) {
                /* Bind to the specified local IP address */
                struct socket *socket = server->ssocket;

                rc = kernel_bind(socket,
                                 (struct sockaddr_unsized *) &server->srcaddr,
                                 sizeof(server->srcaddr));
                if (rc < 0) {
                        struct sockaddr_in *saddr4;
                        struct sockaddr_in6 *saddr6;

                        saddr4 = (struct sockaddr_in *)&server->srcaddr;
                        saddr6 = (struct sockaddr_in6 *)&server->srcaddr;
                        if (saddr6->sin6_family == AF_INET6)
                                cifs_server_dbg(VFS, "Failed to bind to: %pI6c, error: %d\n",
                                         &saddr6->sin6_addr, rc);
                        else
                                cifs_server_dbg(VFS, "Failed to bind to: %pI4, error: %d\n",
                                         &saddr4->sin_addr.s_addr, rc);
                }
        }
        return rc;
}

static int
smb_recv_kvec(struct TCP_Server_Info *server, struct msghdr *msg, size_t *recv)
{
        int rc = 0;
        int retries = 0;
        int msg_flags = server->noblocksnd ? MSG_DONTWAIT : 0;

        *recv = 0;

        while (msg_data_left(msg)) {
                rc = sock_recvmsg(server->ssocket, msg, msg_flags);
                if (rc == -EAGAIN) {
                        retries++;
                        if (retries >= 14 ||
                            (!server->noblocksnd && (retries > 2))) {
                                cifs_server_dbg(VFS, "sends on sock %p stuck for 15 seconds\n",
                                                server->ssocket);
                                return -EAGAIN;
                        }
                        msleep(1 << retries);
                        continue;
                }

                if (rc < 0)
                        return rc;

                if (rc == 0) {
                        cifs_dbg(FYI, "Received no data (TCP RST)\n");
                        return -ECONNABORTED;
                }

                /* recv was at least partially successful */
                *recv += rc;
                retries = 0; /* in case we get ENOSPC on the next send */
        }
        return 0;
}

static int
ip_rfc1001_connect(struct TCP_Server_Info *server)
{
        int rc = 0;
        /*
         * some servers require RFC1001 sessinit before sending
         * negprot - BB check reconnection in case where second
         * sessinit is sent but no second negprot
         */
        struct rfc1002_session_packet req = {};
        struct rfc1002_session_packet resp = {};
        struct msghdr msg = {};
        struct kvec iov = {};
        unsigned int len;
        size_t sent;
        size_t recv;

        req.trailer.session_req.called_len = sizeof(req.trailer.session_req.called_name);

        if (server->server_RFC1001_name[0] != 0)
                rfc1002mangle(req.trailer.session_req.called_name,
                              server->server_RFC1001_name,
                              RFC1001_NAME_LEN_WITH_NULL);
        else
                rfc1002mangle(req.trailer.session_req.called_name,
                              DEFAULT_CIFS_CALLED_NAME,
                              RFC1001_NAME_LEN_WITH_NULL);

        req.trailer.session_req.calling_len = sizeof(req.trailer.session_req.calling_name);

        /* calling name ends in null (byte 16) from old smb convention */
        if (server->workstation_RFC1001_name[0] != 0)
                rfc1002mangle(req.trailer.session_req.calling_name,
                              server->workstation_RFC1001_name,
                              RFC1001_NAME_LEN_WITH_NULL);
        else
                rfc1002mangle(req.trailer.session_req.calling_name,
                              "LINUX_CIFS_CLNT",
                              RFC1001_NAME_LEN_WITH_NULL);

        /*
         * As per rfc1002, @len must be the number of bytes that follows the
         * length field of a rfc1002 session request payload.
         */
        len = sizeof(req.trailer.session_req);
        req.type = RFC1002_SESSION_REQUEST;
        req.flags = 0;
        req.length = cpu_to_be16(len);
        len += offsetof(typeof(req), trailer.session_req);
        iov.iov_base = &req;
        iov.iov_len = len;
        iov_iter_kvec(&msg.msg_iter, ITER_SOURCE, &iov, 1, len);
        rc = smb_send_kvec(server, &msg, &sent);
        if (rc < 0 || len != sent)
                return (rc == -EINTR || rc == -EAGAIN) ? rc : -ECONNABORTED;

        /*
         * RFC1001 layer in at least one server requires very short break before
         * negprot presumably because not expecting negprot to follow so fast.
         * For example DOS SMB servers cannot process negprot if it was received
         * before the server sent response for SESSION_REQUEST packet. So, wait
         * for the response, read it and parse it as it can contain useful error
         * information (e.g. specified server name was incorrect). For example
         * even the latest Windows Server 2022 SMB1 server over port 139 send
         * error if its server name was in SESSION_REQUEST packet incorrect.
         * Nowadays usage of port 139 is not common, so waiting for reply here
         * does not slowing down mounting of common case (over port 445).
         */
        len = offsetof(typeof(resp), trailer);
        iov.iov_base = &resp;
        iov.iov_len = len;
        iov_iter_kvec(&msg.msg_iter, ITER_DEST, &iov, 1, len);
        rc = smb_recv_kvec(server, &msg, &recv);
        if (rc < 0 || recv != len)
                return (rc == -EINTR || rc == -EAGAIN) ? rc : -ECONNABORTED;

        switch (resp.type) {
        case RFC1002_POSITIVE_SESSION_RESPONSE:
                if (be16_to_cpu(resp.length) != 0) {
                        cifs_dbg(VFS, "RFC 1002 positive session response but with invalid non-zero length %u\n",
                                 be16_to_cpu(resp.length));
                        return smb_EIO(smb_eio_trace_rx_pos_sess_resp);
                }
                cifs_dbg(FYI, "RFC 1002 positive session response");
                break;
        case RFC1002_NEGATIVE_SESSION_RESPONSE:
                /* Read RFC1002 response error code and convert it to errno in rc */
                len = sizeof(resp.trailer.neg_ses_resp_error_code);
                iov.iov_base = &resp.trailer.neg_ses_resp_error_code;
                iov.iov_len = len;
                iov_iter_kvec(&msg.msg_iter, ITER_DEST, &iov, 1, len);
                if (be16_to_cpu(resp.length) == len &&
                    smb_recv_kvec(server, &msg, &recv) == 0 &&
                    recv == len) {
                        cifs_dbg(VFS, "RFC 1002 negative session response with error 0x%x\n",
                                 resp.trailer.neg_ses_resp_error_code);
                        switch (resp.trailer.neg_ses_resp_error_code) {
                        case RFC1002_NOT_LISTENING_CALLED:
                                /* server does not listen for specified server name */
                                fallthrough;
                        case RFC1002_NOT_PRESENT:
                                /* server name is incorrect */
                                rc = -ENOENT;
                                cifs_dbg(VFS, "Server rejected NetBIOS servername %.15s\n",
                                         server->server_RFC1001_name[0] ?
                                         server->server_RFC1001_name :
                                         DEFAULT_CIFS_CALLED_NAME);
                                cifs_dbg(VFS, "Specify correct NetBIOS servername in source path or with -o servern= option\n");
                                break;
                        case RFC1002_NOT_LISTENING_CALLING:
                                /* client name was not accepted by server */
                                rc = -EACCES;
                                cifs_dbg(VFS, "Server rejected NetBIOS clientname %.15s\n",
                                         server->workstation_RFC1001_name[0] ?
                                         server->workstation_RFC1001_name :
                                         "LINUX_CIFS_CLNT");
                                cifs_dbg(VFS, "Specify correct NetBIOS clientname with -o netbiosname= option\n");
                                break;
                        case RFC1002_INSUFFICIENT_RESOURCE:
                                /* remote server resource error */
                                smb_EIO(smb_eio_trace_rx_insuff_res);
                                rc = -EREMOTEIO;
                                break;
                        case RFC1002_UNSPECIFIED_ERROR:
                        default:
                                /* other/unknown error */
                                rc = smb_EIO(smb_eio_trace_rx_unspec_error);
                                break;
                        }
                } else {
                        cifs_dbg(VFS, "RFC 1002 negative session response\n");
                        rc = smb_EIO(smb_eio_trace_rx_neg_sess_resp);
                }
                return rc;
        case RFC1002_RETARGET_SESSION_RESPONSE:
                cifs_dbg(VFS, "RFC 1002 retarget session response\n");
                if (be16_to_cpu(resp.length) == sizeof(resp.trailer.retarget_resp)) {
                        len = sizeof(resp.trailer.retarget_resp);
                        iov.iov_base = &resp.trailer.retarget_resp;
                        iov.iov_len = len;
                        iov_iter_kvec(&msg.msg_iter, ITER_DEST, &iov, 1, len);
                        if (smb_recv_kvec(server, &msg, &recv) == 0 && recv == len) {
                                cifs_dbg(VFS, "Server wants to redirect connection\n");
                                cifs_dbg(VFS, "Remount with options -o ip=%pI4,port=%u\n",
                                         &resp.trailer.retarget_resp.retarget_ip_addr,
                                         be16_to_cpu(resp.trailer.retarget_resp.port));
                        }
                }
                cifs_dbg(VFS, "Closing connection\n");
                /* FIXME: Should we automatically redirect to new retarget_resp server? */
                return -EMULTIHOP;
        default:
                cifs_dbg(VFS, "RFC 1002 unknown response type 0x%x\n", resp.type);
                return smb_EIO1(smb_eio_trace_rx_unknown_resp, resp.type);
        }

        server->with_rfc1001 = true;
        return 0;
}

static int
generic_ip_connect(struct TCP_Server_Info *server)
{
        struct sockaddr *saddr;
        struct socket *socket;
        int slen, sfamily;
        __be16 sport;
        int rc = 0;

        saddr = (struct sockaddr *) &server->dstaddr;

        if (server->dstaddr.ss_family == AF_INET6) {
                struct sockaddr_in6 *ipv6 = (struct sockaddr_in6 *)&server->dstaddr;

                sport = ipv6->sin6_port;
                slen = sizeof(struct sockaddr_in6);
                sfamily = AF_INET6;
                cifs_dbg(FYI, "%s: connecting to [%pI6]:%d\n", __func__, &ipv6->sin6_addr,
                                ntohs(sport));
        } else {
                struct sockaddr_in *ipv4 = (struct sockaddr_in *)&server->dstaddr;

                sport = ipv4->sin_port;
                slen = sizeof(struct sockaddr_in);
                sfamily = AF_INET;
                cifs_dbg(FYI, "%s: connecting to %pI4:%d\n", __func__, &ipv4->sin_addr,
                                ntohs(sport));
        }

        if (server->ssocket) {
                socket = server->ssocket;
        } else {
                struct net *net = cifs_net_ns(server);
                struct sock *sk;

                rc = sock_create_kern(net, sfamily, SOCK_STREAM,
                                      IPPROTO_TCP, &server->ssocket);
                if (rc < 0) {
                        cifs_server_dbg(VFS, "Error %d creating socket\n", rc);
                        return rc;
                }

                sk = server->ssocket->sk;
                sk_net_refcnt_upgrade(sk);

                /* BB other socket options to set KEEPALIVE, NODELAY? */
                cifs_dbg(FYI, "Socket created\n");
                socket = server->ssocket;
                socket->sk->sk_allocation = GFP_NOFS;
                socket->sk->sk_use_task_frag = false;
                if (sfamily == AF_INET6)
                        cifs_reclassify_socket6(socket);
                else
                        cifs_reclassify_socket4(socket);
        }

        rc = bind_socket(server);
        if (rc < 0)
                return rc;

        /*
         * Eventually check for other socket options to change from
         * the default. sock_setsockopt not used because it expects
         * user space buffer
         */
        socket->sk->sk_rcvtimeo = 7 * HZ;
        socket->sk->sk_sndtimeo = 5 * HZ;

        /* make the bufsizes depend on wsize/rsize and max requests */
        if (server->noautotune) {
                if (socket->sk->sk_sndbuf < (200 * 1024))
                        socket->sk->sk_sndbuf = 200 * 1024;
                if (socket->sk->sk_rcvbuf < (140 * 1024))
                        socket->sk->sk_rcvbuf = 140 * 1024;
        }

        if (server->tcp_nodelay)
                tcp_sock_set_nodelay(socket->sk);

        cifs_dbg(FYI, "sndbuf %d rcvbuf %d rcvtimeo 0x%lx\n",
                 socket->sk->sk_sndbuf,
                 socket->sk->sk_rcvbuf, socket->sk->sk_rcvtimeo);

        rc = kernel_connect(socket, (struct sockaddr_unsized *)saddr, slen,
                            server->noblockcnt ? O_NONBLOCK : 0);
        /*
         * When mounting SMB root file systems, we do not want to block in
         * connect. Otherwise bail out and then let cifs_reconnect() perform
         * reconnect failover - if possible.
         */
        if (server->noblockcnt && rc == -EINPROGRESS)
                rc = 0;
        if (rc < 0) {
                cifs_dbg(FYI, "Error %d connecting to server\n", rc);
                trace_smb3_connect_err(server->hostname, server->conn_id, &server->dstaddr, rc);
                sock_release(socket);
                server->ssocket = NULL;
                return rc;
        }
        trace_smb3_connect_done(server->hostname, server->conn_id, &server->dstaddr);

        /*
         * Establish RFC1001 NetBIOS session when it was explicitly requested
         * by mount option -o nbsessinit, or when connecting to default RFC1001
         * server port (139) and it was not explicitly disabled by mount option
         * -o nonbsessinit.
         */
        if (server->with_rfc1001 ||
            server->rfc1001_sessinit == 1 ||
            (server->rfc1001_sessinit == -1 && sport == htons(RFC1001_PORT)))
                rc = ip_rfc1001_connect(server);

        return rc;
}

static int
ip_connect(struct TCP_Server_Info *server)
{
        __be16 *sport;
        struct sockaddr_in6 *addr6 = (struct sockaddr_in6 *)&server->dstaddr;
        struct sockaddr_in *addr = (struct sockaddr_in *)&server->dstaddr;

        if (server->dstaddr.ss_family == AF_INET6)
                sport = &addr6->sin6_port;
        else
                sport = &addr->sin_port;

        if (*sport == 0) {
                int rc;

                /* try with 445 port at first */
                *sport = htons(CIFS_PORT);

                rc = generic_ip_connect(server);
                if (rc >= 0)
                        return rc;

                /* if it failed, try with 139 port */
                *sport = htons(RFC1001_PORT);
        }

        return generic_ip_connect(server);
}

int cifs_setup_cifs_sb(struct cifs_sb_info *cifs_sb)
{
        struct smb3_fs_context *ctx = cifs_sb->ctx;
        unsigned int sbflags;
        int rc = 0;

        INIT_DELAYED_WORK(&cifs_sb->prune_tlinks, cifs_prune_tlinks);
        INIT_LIST_HEAD(&cifs_sb->tcon_sb_link);

        spin_lock_init(&cifs_sb->tlink_tree_lock);
        cifs_sb->tlink_tree = RB_ROOT;

        cifs_dbg(FYI, "file mode: %04ho  dir mode: %04ho\n",
                 ctx->file_mode, ctx->dir_mode);

        /* this is needed for ASCII cp to Unicode converts */
        if (ctx->iocharset == NULL) {
                /* load_nls_default cannot return null */
                cifs_sb->local_nls = load_nls_default();
        } else {
                cifs_sb->local_nls = load_nls(ctx->iocharset);
                if (cifs_sb->local_nls == NULL) {
                        cifs_dbg(VFS, "CIFS mount error: iocharset %s not found\n",
                                 ctx->iocharset);
                        return -ELIBACC;
                }
        }
        ctx->local_nls = cifs_sb->local_nls;

        sbflags = smb3_update_mnt_flags(cifs_sb);

        if (ctx->direct_io)
                cifs_dbg(FYI, "mounting share using direct i/o\n");
        if (ctx->cache_ro) {
                cifs_dbg(VFS, "mounting share with read only caching. Ensure that the share will not be modified while in use.\n");
                sbflags |= CIFS_MOUNT_RO_CACHE;
        } else if (ctx->cache_rw) {
                cifs_dbg(VFS, "mounting share in single client RW caching mode. Ensure that no other systems will be accessing the share.\n");
                sbflags |= CIFS_MOUNT_RO_CACHE | CIFS_MOUNT_RW_CACHE;
        }

        if ((ctx->cifs_acl) && (ctx->dynperm))
                cifs_dbg(VFS, "mount option dynperm ignored if cifsacl mount option supported\n");

        if (ctx->prepath) {
                cifs_sb->prepath = kstrdup(ctx->prepath, GFP_KERNEL);
                if (cifs_sb->prepath == NULL)
                        rc = -ENOMEM;
                else
                        sbflags |= CIFS_MOUNT_USE_PREFIX_PATH;
        }

        atomic_set(&cifs_sb->mnt_cifs_flags, sbflags);
        return rc;
}

/* Release all succeed connections */
void cifs_mount_put_conns(struct cifs_mount_ctx *mnt_ctx)
{
        struct cifs_sb_info *cifs_sb = mnt_ctx->cifs_sb;
        int rc = 0;

        if (mnt_ctx->tcon)
                cifs_put_tcon(mnt_ctx->tcon, netfs_trace_tcon_ref_put_mnt_ctx);
        else if (mnt_ctx->ses)
                cifs_put_smb_ses(mnt_ctx->ses);
        else if (mnt_ctx->server)
                cifs_put_tcp_session(mnt_ctx->server, 0);
        mnt_ctx->ses = NULL;
        mnt_ctx->tcon = NULL;
        mnt_ctx->server = NULL;
        atomic_andnot(CIFS_MOUNT_POSIX_PATHS, &cifs_sb->mnt_cifs_flags);
        free_xid(mnt_ctx->xid);
}

int cifs_mount_get_session(struct cifs_mount_ctx *mnt_ctx)
{
        struct TCP_Server_Info *server = NULL;
        struct smb3_fs_context *ctx;
        struct cifs_ses *ses = NULL;
        unsigned int xid;
        int rc = 0;

        xid = get_xid();

        if (WARN_ON_ONCE(!mnt_ctx || !mnt_ctx->fs_ctx)) {
                rc = -EINVAL;
                goto out;
        }
        ctx = mnt_ctx->fs_ctx;

        /* get a reference to a tcp session */
        server = cifs_get_tcp_session(ctx, NULL);
        if (IS_ERR(server)) {
                rc = PTR_ERR(server);
                server = NULL;
                goto out;
        }

        /* get a reference to a SMB session */
        ses = cifs_get_smb_ses(server, ctx);
        if (IS_ERR(ses)) {
                rc = PTR_ERR(ses);
                ses = NULL;
                goto out;
        }

        if ((ctx->persistent == true) && (!(ses->server->capabilities &
                                            SMB2_GLOBAL_CAP_PERSISTENT_HANDLES))) {
                cifs_server_dbg(VFS, "persistent handles not supported by server\n");
                rc = -EOPNOTSUPP;
        }

out:
        mnt_ctx->xid = xid;
        mnt_ctx->server = server;
        mnt_ctx->ses = ses;
        mnt_ctx->tcon = NULL;

        return rc;
}

int cifs_mount_get_tcon(struct cifs_mount_ctx *mnt_ctx)
{
        struct TCP_Server_Info *server;
        struct cifs_tcon *tcon = NULL;
        struct cifs_sb_info *cifs_sb;
        struct smb3_fs_context *ctx;
        unsigned int sbflags;
        int rc = 0;

        if (WARN_ON_ONCE(!mnt_ctx))
                return -EINVAL;
        if (WARN_ON_ONCE(!mnt_ctx->server || !mnt_ctx->ses ||
                         !mnt_ctx->fs_ctx || !mnt_ctx->cifs_sb)) {
                mnt_ctx->tcon = NULL;
                return -EINVAL;
        }
        server = mnt_ctx->server;
        ctx = mnt_ctx->fs_ctx;
        cifs_sb = mnt_ctx->cifs_sb;
        sbflags = cifs_sb_flags(cifs_sb);

        /* search for existing tcon to this server share */
        tcon = cifs_get_tcon(mnt_ctx->ses, ctx);
        if (IS_ERR(tcon)) {
                rc = PTR_ERR(tcon);
                tcon = NULL;
                goto out;
        }

        /*
         * if new SMB3.11 POSIX extensions are supported, do not change anything in the
         * path (i.e., do not remap / and \ and do not map any special characters)
         */
        if (tcon->posix_extensions) {
                sbflags |= CIFS_MOUNT_POSIX_PATHS;
                sbflags &= ~(CIFS_MOUNT_MAP_SFM_CHR |
                             CIFS_MOUNT_MAP_SPECIAL_CHR);
        }

#ifdef CONFIG_CIFS_ALLOW_INSECURE_LEGACY
        /* tell server which Unix caps we support */
        if (cap_unix(tcon->ses)) {
                /*
                 * reset of caps checks mount to see if unix extensions disabled
                 * for just this mount.
                 */
                reset_cifs_unix_caps(mnt_ctx->xid, tcon, cifs_sb, ctx);
                spin_lock(&tcon->ses->server->srv_lock);
                if ((tcon->ses->server->tcpStatus == CifsNeedReconnect) &&
                    (le64_to_cpu(tcon->fsUnixInfo.Capability) &
                     CIFS_UNIX_TRANSPORT_ENCRYPTION_MANDATORY_CAP)) {
                        spin_unlock(&tcon->ses->server->srv_lock);
                        rc = -EACCES;
                        goto out;
                }
                spin_unlock(&tcon->ses->server->srv_lock);
        } else
#endif /* CONFIG_CIFS_ALLOW_INSECURE_LEGACY */
                tcon->unix_ext = 0; /* server does not support them */

        /* do not care if a following call succeed - informational */
        if (!tcon->pipe && server->ops->qfs_tcon) {
                server->ops->qfs_tcon(mnt_ctx->xid, tcon, cifs_sb);
                if (sbflags & CIFS_MOUNT_RO_CACHE) {
                        if (tcon->fsDevInfo.DeviceCharacteristics &
                            cpu_to_le32(FILE_READ_ONLY_DEVICE))
                                cifs_dbg(VFS, "mounted to read only share\n");
                        else if (!(sbflags & CIFS_MOUNT_RW_CACHE))
                                cifs_dbg(VFS, "read only mount of RW share\n");
                        /* no need to log a RW mount of a typical RW share */
                }
        }

        cifs_negotiate_iosize(server, cifs_sb->ctx, tcon);
        /*
         * The cookie is initialized from volume info returned above.
         * Inside cifs_fscache_get_super_cookie it checks
         * that we do not get super cookie twice.
         */
        if (sbflags & CIFS_MOUNT_FSCACHE)
                cifs_fscache_get_super_cookie(tcon);

out:
        mnt_ctx->tcon = tcon;
        atomic_set(&cifs_sb->mnt_cifs_flags, sbflags);
        return rc;
}

static int mount_setup_tlink(struct cifs_sb_info *cifs_sb, struct cifs_ses *ses,
                             struct cifs_tcon *tcon)
{
        struct tcon_link *tlink;

        /* hang the tcon off of the superblock */
        tlink = kzalloc_obj(*tlink);
        if (tlink == NULL)
                return -ENOMEM;

        tlink->tl_uid = ses->linux_uid;
        tlink->tl_tcon = tcon;
        tlink->tl_time = jiffies;
        set_bit(TCON_LINK_MASTER, &tlink->tl_flags);
        set_bit(TCON_LINK_IN_TREE, &tlink->tl_flags);

        cifs_sb->master_tlink = tlink;
        spin_lock(&cifs_sb->tlink_tree_lock);
        tlink_rb_insert(&cifs_sb->tlink_tree, tlink);
        spin_unlock(&cifs_sb->tlink_tree_lock);

        spin_lock(&tcon->sb_list_lock);
        list_add(&cifs_sb->tcon_sb_link, &tcon->cifs_sb_list);
        spin_unlock(&tcon->sb_list_lock);

        queue_delayed_work(cifsiod_wq, &cifs_sb->prune_tlinks,
                                TLINK_IDLE_EXPIRE);
        return 0;
}

static int
cifs_are_all_path_components_accessible(struct TCP_Server_Info *server,
                                        unsigned int xid,
                                        struct cifs_tcon *tcon,
                                        struct cifs_sb_info *cifs_sb,
                                        char *full_path,
                                        int added_treename)
{
        int rc;
        char *s;
        char sep, tmp;
        int skip = added_treename ? 1 : 0;

        sep = CIFS_DIR_SEP(cifs_sb);
        s = full_path;

        rc = server->ops->is_path_accessible(xid, tcon, cifs_sb, "");
        while (rc == 0) {
                /* skip separators */
                while (*s == sep)
                        s++;
                if (!*s)
                        break;
                /* next separator */
                while (*s && *s != sep)
                        s++;
                /*
                 * if the treename is added, we then have to skip the first
                 * part within the separators
                 */
                if (skip) {
                        skip = 0;
                        continue;
                }
                /*
                 * temporarily null-terminate the path at the end of
                 * the current component
                 */
                tmp = *s;
                *s = 0;
                rc = server->ops->is_path_accessible(xid, tcon, cifs_sb,
                                                     full_path);
                *s = tmp;
        }
        return rc;
}

/*
 * Check if path is remote (i.e. a DFS share).
 *
 * Return -EREMOTE if it is, otherwise 0 or -errno.
 */
int cifs_is_path_remote(struct cifs_mount_ctx *mnt_ctx)
{
        int rc;
        struct cifs_sb_info *cifs_sb = mnt_ctx->cifs_sb;
        struct TCP_Server_Info *server = mnt_ctx->server;
        unsigned int xid = mnt_ctx->xid;
        struct cifs_tcon *tcon = mnt_ctx->tcon;
        struct smb3_fs_context *ctx = mnt_ctx->fs_ctx;
        char *full_path;

        if (!server->ops->is_path_accessible)
                return -EOPNOTSUPP;

        /*
         * cifs_build_path_to_root works only when we have a valid tcon
         */
        full_path = cifs_build_path_to_root(ctx, cifs_sb, tcon,
                                            tcon->Flags & SMB_SHARE_IS_IN_DFS);
        if (full_path == NULL)
                return -ENOMEM;

        cifs_dbg(FYI, "%s: full_path: %s\n", __func__, full_path);

        rc = server->ops->is_path_accessible(xid, tcon, cifs_sb,
                                             full_path);
        if (rc != 0 && rc != -EREMOTE)
                goto out;

        if (rc != -EREMOTE) {
                rc = cifs_are_all_path_components_accessible(server, xid, tcon,
                        cifs_sb, full_path, tcon->Flags & SMB_SHARE_IS_IN_DFS);
                if (rc != 0) {
                        cifs_server_dbg(VFS, "cannot query dirs between root and final path, enabling CIFS_MOUNT_USE_PREFIX_PATH\n");
                        atomic_or(CIFS_MOUNT_USE_PREFIX_PATH,
                                  &cifs_sb->mnt_cifs_flags);
                        rc = 0;
                }
        }

out:
        kfree(full_path);
        return rc;
}

static struct mchan_mount *
mchan_mount_alloc(struct cifs_ses *ses)
{
        struct mchan_mount *mchan_mount;

        mchan_mount = kzalloc_obj(*mchan_mount);
        if (!mchan_mount)
                return ERR_PTR(-ENOMEM);

        INIT_WORK(&mchan_mount->work, mchan_mount_work_fn);

        spin_lock(&cifs_tcp_ses_lock);
        cifs_smb_ses_inc_refcount(ses);
        spin_unlock(&cifs_tcp_ses_lock);
        mchan_mount->ses = ses;

        return mchan_mount;
}

static void
mchan_mount_free(struct mchan_mount *mchan_mount)
{
        cifs_put_smb_ses(mchan_mount->ses);
        kfree(mchan_mount);
}

static void
mchan_mount_work_fn(struct work_struct *work)
{
        struct mchan_mount *mchan_mount = container_of(work, struct mchan_mount, work);

        smb3_update_ses_channels(mchan_mount->ses,
                                 mchan_mount->ses->server,
                                 false /* from_reconnect */,
                                 false /* disable_mchan */);

        mchan_mount_free(mchan_mount);
}

#ifdef CONFIG_CIFS_DFS_UPCALL
int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb3_fs_context *ctx)
{
        struct cifs_mount_ctx mnt_ctx = { .cifs_sb = cifs_sb, .fs_ctx = ctx, };
        struct mchan_mount *mchan_mount = NULL;
        int rc;

        rc = dfs_mount_share(&mnt_ctx);
        if (rc)
                goto error;

        if (ctx->multichannel) {
                mchan_mount = mchan_mount_alloc(mnt_ctx.ses);
                if (IS_ERR(mchan_mount)) {
                        rc = PTR_ERR(mchan_mount);
                        goto error;
                }
        }

        if (!ctx->dfs_conn)
                goto out;

        /*
         * After reconnecting to a different server, unique ids won't match anymore, so we disable
         * serverino. This prevents dentry revalidation to think the dentry are stale (ESTALE).
         */
        cifs_autodisable_serverino(cifs_sb);
        /*
         * Force the use of prefix path to support failover on DFS paths that resolve to targets
         * that have different prefix paths.
         */
        atomic_or(CIFS_MOUNT_USE_PREFIX_PATH, &cifs_sb->mnt_cifs_flags);
        kfree(cifs_sb->prepath);
        cifs_sb->prepath = ctx->prepath;
        ctx->prepath = NULL;

out:
        rc = mount_setup_tlink(cifs_sb, mnt_ctx.ses, mnt_ctx.tcon);
        if (rc)
                goto error;

        if (ctx->multichannel)
                queue_work(cifsiod_wq, &mchan_mount->work);

        free_xid(mnt_ctx.xid);
        return rc;

error:
        if (ctx->multichannel && !IS_ERR_OR_NULL(mchan_mount))
                mchan_mount_free(mchan_mount);
        cifs_mount_put_conns(&mnt_ctx);
        return rc;
}
#else
int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb3_fs_context *ctx)
{
        int rc = 0;
        struct cifs_mount_ctx mnt_ctx = { .cifs_sb = cifs_sb, .fs_ctx = ctx, };
        struct mchan_mount *mchan_mount = NULL;

        rc = cifs_mount_get_session(&mnt_ctx);
        if (rc)
                goto error;

        rc = cifs_mount_get_tcon(&mnt_ctx);
        if (!rc) {
                /*
                 * Prevent superblock from being created with any missing
                 * connections.
                 */
                if (WARN_ON(!mnt_ctx.server))
                        rc = -EHOSTDOWN;
                else if (WARN_ON(!mnt_ctx.ses))
                        rc = -EACCES;
                else if (WARN_ON(!mnt_ctx.tcon))
                        rc = -ENOENT;
        }
        if (rc)
                goto error;

        rc = cifs_is_path_remote(&mnt_ctx);
        if (rc == -EREMOTE)
                rc = -EOPNOTSUPP;
        if (rc)
                goto error;

        if (ctx->multichannel) {
                mchan_mount = mchan_mount_alloc(mnt_ctx.ses);
                if (IS_ERR(mchan_mount)) {
                        rc = PTR_ERR(mchan_mount);
                        goto error;
                }
        }

        rc = mount_setup_tlink(cifs_sb, mnt_ctx.ses, mnt_ctx.tcon);
        if (rc)
                goto error;

        if (ctx->multichannel)
                queue_work(cifsiod_wq, &mchan_mount->work);

        free_xid(mnt_ctx.xid);
        return rc;

error:
        if (ctx->multichannel && !IS_ERR_OR_NULL(mchan_mount))
                mchan_mount_free(mchan_mount);
        cifs_mount_put_conns(&mnt_ctx);
        return rc;
}
#endif

static void delayed_free(struct rcu_head *p)
{
        struct cifs_sb_info *cifs_sb = container_of(p, struct cifs_sb_info, rcu);

        unload_nls(cifs_sb->local_nls);
        smb3_cleanup_fs_context(cifs_sb->ctx);
        kfree(cifs_sb);
}

void
cifs_umount(struct cifs_sb_info *cifs_sb)
{
        struct rb_root *root = &cifs_sb->tlink_tree;
        struct rb_node *node;
        struct tcon_link *tlink;
        struct cifs_tcon *tcon = NULL;

        cancel_delayed_work_sync(&cifs_sb->prune_tlinks);

        if (cifs_sb->master_tlink) {
                tcon = cifs_sb->master_tlink->tl_tcon;
                if (tcon) {
                        spin_lock(&tcon->sb_list_lock);
                        list_del_init(&cifs_sb->tcon_sb_link);
                        spin_unlock(&tcon->sb_list_lock);
                }
        }

        spin_lock(&cifs_sb->tlink_tree_lock);
        while ((node = rb_first(root))) {
                tlink = rb_entry(node, struct tcon_link, tl_rbnode);
                cifs_get_tlink(tlink);
                clear_bit(TCON_LINK_IN_TREE, &tlink->tl_flags);
                rb_erase(node, root);

                spin_unlock(&cifs_sb->tlink_tree_lock);
                cifs_put_tlink(tlink);
                spin_lock(&cifs_sb->tlink_tree_lock);
        }
        spin_unlock(&cifs_sb->tlink_tree_lock);

        kfree(cifs_sb->prepath);
        call_rcu(&cifs_sb->rcu, delayed_free);
}

int
cifs_negotiate_protocol(const unsigned int xid, struct cifs_ses *ses,
                        struct TCP_Server_Info *server)
{
        bool in_retry = false;
        int rc = 0;

        if (!server->ops->need_neg || !server->ops->negotiate)
                return -ENOSYS;

retry:
        /* only send once per connect */
        spin_lock(&server->srv_lock);
        if (server->tcpStatus != CifsGood &&
            server->tcpStatus != CifsNew &&
            server->tcpStatus != CifsNeedNegotiate) {
                spin_unlock(&server->srv_lock);
                return -EHOSTDOWN;
        }

        if (!server->ops->need_neg(server) &&
            server->tcpStatus == CifsGood) {
                spin_unlock(&server->srv_lock);
                return 0;
        }

        server->tcpStatus = CifsInNegotiate;
        server->neg_start = jiffies;
        spin_unlock(&server->srv_lock);

        rc = server->ops->negotiate(xid, ses, server);
        if (rc == -EAGAIN) {
                /* Allow one retry attempt */
                if (!in_retry) {
                        in_retry = true;
                        goto retry;
                }
                rc = -EHOSTDOWN;
        }
        if (rc == 0) {
                spin_lock(&server->srv_lock);
                if (server->tcpStatus == CifsInNegotiate)
                        server->tcpStatus = CifsGood;
                else
                        rc = -EHOSTDOWN;
                spin_unlock(&server->srv_lock);
        } else {
                spin_lock(&server->srv_lock);
                if (server->tcpStatus == CifsInNegotiate)
                        server->tcpStatus = CifsNeedNegotiate;
                spin_unlock(&server->srv_lock);
        }

        return rc;
}

int
cifs_setup_session(const unsigned int xid, struct cifs_ses *ses,
                   struct TCP_Server_Info *server,
                   struct nls_table *nls_info)
{
        int rc = 0;
        struct TCP_Server_Info *pserver = SERVER_IS_CHAN(server) ? server->primary_server : server;
        struct sockaddr_in6 *addr6 = (struct sockaddr_in6 *)&pserver->dstaddr;
        struct sockaddr_in *addr = (struct sockaddr_in *)&pserver->dstaddr;
        bool is_binding = false;
        bool new_ses;

        spin_lock(&ses->ses_lock);
        new_ses = ses->ses_status == SES_NEW;
        cifs_dbg(FYI, "%s: channel connect bitmap: 0x%lx\n",
                 __func__, ses->chans_need_reconnect);

        if (ses->ses_status != SES_GOOD &&
            ses->ses_status != SES_NEW &&
            ses->ses_status != SES_NEED_RECON) {
                spin_unlock(&ses->ses_lock);
                return -EHOSTDOWN;
        }

        /* only send once per connect */
        spin_lock(&ses->chan_lock);
        if (CIFS_ALL_CHANS_GOOD(ses)) {
                if (ses->ses_status == SES_NEED_RECON)
                        ses->ses_status = SES_GOOD;
                spin_unlock(&ses->chan_lock);
                spin_unlock(&ses->ses_lock);
                return 0;
        }

        cifs_chan_set_in_reconnect(ses, server);
        is_binding = !CIFS_ALL_CHANS_NEED_RECONNECT(ses);
        spin_unlock(&ses->chan_lock);

        if (!is_binding) {
                ses->ses_status = SES_IN_SETUP;

                /* force iface_list refresh */
                spin_lock(&ses->iface_lock);
                ses->iface_last_update = 0;
                spin_unlock(&ses->iface_lock);
        }
        spin_unlock(&ses->ses_lock);

        /* update ses ip_addr only for primary chan */
        if (server == pserver) {
                if (server->dstaddr.ss_family == AF_INET6)
                        scnprintf(ses->ip_addr, sizeof(ses->ip_addr), "%pI6", &addr6->sin6_addr);
                else
                        scnprintf(ses->ip_addr, sizeof(ses->ip_addr), "%pI4", &addr->sin_addr);
        }

        if (!is_binding) {
                ses->capabilities = server->capabilities;
                if (!linuxExtEnabled)
                        ses->capabilities &= (~server->vals->cap_unix);

                /*
                 * Check if the server supports specified encoding mode.
                 * Zero value in vals->cap_unicode indidcates that chosen
                 * protocol dialect does not support non-UNICODE mode.
                 */
                if (ses->unicode == 1 && server->vals->cap_unicode != 0 &&
                    !(server->capabilities & server->vals->cap_unicode)) {
                        cifs_dbg(VFS, "Server does not support mounting in UNICODE mode\n");
                        rc = -EOPNOTSUPP;
                } else if (ses->unicode == 0 && server->vals->cap_unicode == 0) {
                        cifs_dbg(VFS, "Server does not support mounting in non-UNICODE mode\n");
                        rc = -EOPNOTSUPP;
                } else if (ses->unicode == 0) {
                        /*
                         * When UNICODE mode was explicitly disabled then
                         * do not announce client UNICODE capability.
                         */
                        ses->capabilities &= (~server->vals->cap_unicode);
                }

                if (ses->auth_key.response) {
                        cifs_dbg(FYI, "Free previous auth_key.response = %p\n",
                                 ses->auth_key.response);
                        kfree_sensitive(ses->auth_key.response);
                        ses->auth_key.response = NULL;
                        ses->auth_key.len = 0;
                }
        }

        cifs_dbg(FYI, "Security Mode: 0x%x Capabilities: 0x%x TimeAdjust: %d\n",
                 server->sec_mode, server->capabilities, server->timeAdj);

        if (!rc) {
                if (server->ops->sess_setup)
                        rc = server->ops->sess_setup(xid, ses, server, nls_info);
                else
                        rc = -ENOSYS;
        }

        if (rc) {
                if (new_ses) {
                        cifs_server_dbg(VFS, "failed to create a new SMB session with %s: %d\n",
                                        get_security_type_str(ses->sectype), rc);
                }
                spin_lock(&ses->ses_lock);
                if (ses->ses_status == SES_IN_SETUP)
                        ses->ses_status = SES_NEED_RECON;
                spin_lock(&ses->chan_lock);
                cifs_chan_clear_in_reconnect(ses, server);
                spin_unlock(&ses->chan_lock);
                spin_unlock(&ses->ses_lock);
        } else {
                spin_lock(&ses->ses_lock);
                if (ses->ses_status == SES_IN_SETUP)
                        ses->ses_status = SES_GOOD;
                spin_lock(&ses->chan_lock);
                cifs_chan_clear_in_reconnect(ses, server);
                cifs_chan_clear_need_reconnect(ses, server);
                spin_unlock(&ses->chan_lock);
                spin_unlock(&ses->ses_lock);
        }

        return rc;
}

static int
cifs_set_vol_auth(struct smb3_fs_context *ctx, struct cifs_ses *ses)
{
        ctx->sectype = ses->sectype;

        /* krb5 is special, since we don't need username or pw */
        if (ctx->sectype == Kerberos)
                return 0;

        return cifs_set_cifscreds(ctx, ses);
}

static struct cifs_tcon *
cifs_construct_tcon(struct cifs_sb_info *cifs_sb, kuid_t fsuid)
{
        int rc;
        struct cifs_tcon *master_tcon = cifs_sb_master_tcon(cifs_sb);
        struct cifs_ses *ses;
        struct cifs_tcon *tcon = NULL;
        struct smb3_fs_context *ctx;
        char *origin_fullpath = NULL;

        ctx = kzalloc_obj(*ctx);
        if (ctx == NULL)
                return ERR_PTR(-ENOMEM);

        ctx->local_nls = cifs_sb->local_nls;
        ctx->linux_uid = fsuid;
        ctx->cred_uid = fsuid;
        ctx->UNC = master_tcon->tree_name;
        ctx->retry = master_tcon->retry;
        ctx->nocase = master_tcon->nocase;
        ctx->nohandlecache = master_tcon->nohandlecache;
        ctx->local_lease = master_tcon->local_lease;
        ctx->no_lease = master_tcon->no_lease;
        ctx->resilient = master_tcon->use_resilient;
        ctx->persistent = master_tcon->use_persistent;
        ctx->handle_timeout = master_tcon->handle_timeout;
        ctx->no_linux_ext = !master_tcon->unix_ext;
        ctx->linux_ext = master_tcon->posix_extensions;
        ctx->sectype = master_tcon->ses->sectype;
        ctx->sign = master_tcon->ses->sign;
        ctx->seal = master_tcon->seal;
        ctx->witness = master_tcon->use_witness;
        ctx->dfs_root_ses = master_tcon->ses->dfs_root_ses;
        ctx->unicode = master_tcon->ses->unicode;

        rc = cifs_set_vol_auth(ctx, master_tcon->ses);
        if (rc) {
                tcon = ERR_PTR(rc);
                goto out;
        }

        /* get a reference for the same TCP session */
        spin_lock(&cifs_tcp_ses_lock);
        ++master_tcon->ses->server->srv_count;
        spin_unlock(&cifs_tcp_ses_lock);

        ses = cifs_get_smb_ses(master_tcon->ses->server, ctx);
        if (IS_ERR(ses)) {
                tcon = ERR_CAST(ses);
                cifs_put_tcp_session(master_tcon->ses->server, 0);
                goto out;
        }

#ifdef CONFIG_CIFS_DFS_UPCALL
        spin_lock(&master_tcon->tc_lock);
        if (master_tcon->origin_fullpath) {
                spin_unlock(&master_tcon->tc_lock);
                origin_fullpath = dfs_get_path(cifs_sb, cifs_sb->ctx->source);
                if (IS_ERR(origin_fullpath)) {
                        tcon = ERR_CAST(origin_fullpath);
                        origin_fullpath = NULL;
                        cifs_put_smb_ses(ses);
                        goto out;
                }
        } else {
                spin_unlock(&master_tcon->tc_lock);
        }
#endif

        tcon = cifs_get_tcon(ses, ctx);
        if (IS_ERR(tcon)) {
                cifs_put_smb_ses(ses);
                goto out;
        }

#ifdef CONFIG_CIFS_DFS_UPCALL
        if (origin_fullpath) {
                spin_lock(&tcon->tc_lock);
                tcon->origin_fullpath = origin_fullpath;
                spin_unlock(&tcon->tc_lock);
                origin_fullpath = NULL;
                queue_delayed_work(dfscache_wq, &tcon->dfs_cache_work,
                                   dfs_cache_get_ttl() * HZ);
        }
#endif

#ifdef CONFIG_CIFS_ALLOW_INSECURE_LEGACY
        if (cap_unix(ses))
                reset_cifs_unix_caps(0, tcon, NULL, ctx);
#endif /* CONFIG_CIFS_ALLOW_INSECURE_LEGACY */

out:
        kfree(ctx->username);
        kfree(ctx->domainname);
        kfree_sensitive(ctx->password);
        kfree(origin_fullpath);
        kfree(ctx);

        return tcon;
}

struct cifs_tcon *
cifs_sb_master_tcon(struct cifs_sb_info *cifs_sb)
{
        return tlink_tcon(cifs_sb_master_tlink(cifs_sb));
}

/* find and return a tlink with given uid */
static struct tcon_link *
tlink_rb_search(struct rb_root *root, kuid_t uid)
{
        struct rb_node *node = root->rb_node;
        struct tcon_link *tlink;

        while (node) {
                tlink = rb_entry(node, struct tcon_link, tl_rbnode);

                if (uid_gt(tlink->tl_uid, uid))
                        node = node->rb_left;
                else if (uid_lt(tlink->tl_uid, uid))
                        node = node->rb_right;
                else
                        return tlink;
        }
        return NULL;
}

/* insert a tcon_link into the tree */
static void
tlink_rb_insert(struct rb_root *root, struct tcon_link *new_tlink)
{
        struct rb_node **new = &(root->rb_node), *parent = NULL;
        struct tcon_link *tlink;

        while (*new) {
                tlink = rb_entry(*new, struct tcon_link, tl_rbnode);
                parent = *new;

                if (uid_gt(tlink->tl_uid, new_tlink->tl_uid))
                        new = &((*new)->rb_left);
                else
                        new = &((*new)->rb_right);
        }

        rb_link_node(&new_tlink->tl_rbnode, parent, new);
        rb_insert_color(&new_tlink->tl_rbnode, root);
}

/*
 * Find or construct an appropriate tcon given a cifs_sb and the fsuid of the
 * current task.
 *
 * If the superblock doesn't refer to a multiuser mount, then just return
 * the master tcon for the mount.
 *
 * First, search the rbtree for an existing tcon for this fsuid. If one
 * exists, then check to see if it's pending construction. If it is then wait
 * for construction to complete. Once it's no longer pending, check to see if
 * it failed and either return an error or retry construction, depending on
 * the timeout.
 *
 * If one doesn't exist then insert a new tcon_link struct into the tree and
 * try to construct a new one.
 *
 * REMEMBER to call cifs_put_tlink() after successful calls to cifs_sb_tlink,
 * to avoid refcount issues
 */
struct tcon_link *
cifs_sb_tlink(struct cifs_sb_info *cifs_sb)
{
        struct tcon_link *tlink, *newtlink;
        kuid_t fsuid = current_fsuid();
        int err;

        if (!(cifs_sb_flags(cifs_sb) & CIFS_MOUNT_MULTIUSER))
                return cifs_get_tlink(cifs_sb_master_tlink(cifs_sb));

        spin_lock(&cifs_sb->tlink_tree_lock);
        tlink = tlink_rb_search(&cifs_sb->tlink_tree, fsuid);
        if (tlink)
                cifs_get_tlink(tlink);
        spin_unlock(&cifs_sb->tlink_tree_lock);

        if (tlink == NULL) {
                newtlink = kzalloc_obj(*tlink);
                if (newtlink == NULL)
                        return ERR_PTR(-ENOMEM);
                newtlink->tl_uid = fsuid;
                newtlink->tl_tcon = ERR_PTR(-EACCES);
                set_bit(TCON_LINK_PENDING, &newtlink->tl_flags);
                set_bit(TCON_LINK_IN_TREE, &newtlink->tl_flags);
                cifs_get_tlink(newtlink);

                spin_lock(&cifs_sb->tlink_tree_lock);
                /* was one inserted after previous search? */
                tlink = tlink_rb_search(&cifs_sb->tlink_tree, fsuid);
                if (tlink) {
                        cifs_get_tlink(tlink);
                        spin_unlock(&cifs_sb->tlink_tree_lock);
                        kfree(newtlink);
                        goto wait_for_construction;
                }
                tlink = newtlink;
                tlink_rb_insert(&cifs_sb->tlink_tree, tlink);
                spin_unlock(&cifs_sb->tlink_tree_lock);
        } else {
wait_for_construction:
                err = wait_on_bit(&tlink->tl_flags, TCON_LINK_PENDING,
                                  TASK_INTERRUPTIBLE);
                if (err) {
                        cifs_put_tlink(tlink);
                        return ERR_PTR(-ERESTARTSYS);
                }

                /* if it's good, return it */
                if (!IS_ERR(tlink->tl_tcon))
                        return tlink;

                /* return error if we tried this already recently */
                if (time_before(jiffies, tlink->tl_time + TLINK_ERROR_EXPIRE)) {
                        err = PTR_ERR(tlink->tl_tcon);
                        cifs_put_tlink(tlink);
                        return ERR_PTR(err);
                }

                if (test_and_set_bit(TCON_LINK_PENDING, &tlink->tl_flags))
                        goto wait_for_construction;
        }

        tlink->tl_tcon = cifs_construct_tcon(cifs_sb, fsuid);
        clear_bit(TCON_LINK_PENDING, &tlink->tl_flags);
        wake_up_bit(&tlink->tl_flags, TCON_LINK_PENDING);

        if (IS_ERR(tlink->tl_tcon)) {
                err = PTR_ERR(tlink->tl_tcon);
                if (err == -ENOKEY)
                        err = -EACCES;
                cifs_put_tlink(tlink);
                return ERR_PTR(err);
        }

        return tlink;
}

/*
 * periodic workqueue job that scans tcon_tree for a superblock and closes
 * out tcons.
 */
static void
cifs_prune_tlinks(struct work_struct *work)
{
        struct cifs_sb_info *cifs_sb = container_of(work, struct cifs_sb_info,
                                                    prune_tlinks.work);
        struct rb_root *root = &cifs_sb->tlink_tree;
        struct rb_node *node;
        struct rb_node *tmp;
        struct tcon_link *tlink;

        /*
         * Because we drop the spinlock in the loop in order to put the tlink
         * it's not guarded against removal of links from the tree. The only
         * places that remove entries from the tree are this function and
         * umounts. Because this function is non-reentrant and is canceled
         * before umount can proceed, this is safe.
         */
        spin_lock(&cifs_sb->tlink_tree_lock);
        node = rb_first(root);
        while (node != NULL) {
                tmp = node;
                node = rb_next(tmp);
                tlink = rb_entry(tmp, struct tcon_link, tl_rbnode);

                if (test_bit(TCON_LINK_MASTER, &tlink->tl_flags) ||
                    atomic_read(&tlink->tl_count) != 0 ||
                    time_after(tlink->tl_time + TLINK_IDLE_EXPIRE, jiffies))
                        continue;

                cifs_get_tlink(tlink);
                clear_bit(TCON_LINK_IN_TREE, &tlink->tl_flags);
                rb_erase(tmp, root);

                spin_unlock(&cifs_sb->tlink_tree_lock);
                cifs_put_tlink(tlink);
                spin_lock(&cifs_sb->tlink_tree_lock);
        }
        spin_unlock(&cifs_sb->tlink_tree_lock);

        queue_delayed_work(cifsiod_wq, &cifs_sb->prune_tlinks,
                                TLINK_IDLE_EXPIRE);
}

#ifndef CONFIG_CIFS_DFS_UPCALL
int cifs_tree_connect(const unsigned int xid, struct cifs_tcon *tcon)
{
        const struct smb_version_operations *ops = tcon->ses->server->ops;
        int rc;

        /* only send once per connect */
        spin_lock(&tcon->tc_lock);

        /* if tcon is marked for needing reconnect, update state */
        if (tcon->need_reconnect)
                tcon->status = TID_NEED_TCON;

        if (tcon->status == TID_GOOD) {
                spin_unlock(&tcon->tc_lock);
                return 0;
        }

        if (tcon->status != TID_NEW &&
            tcon->status != TID_NEED_TCON) {
                spin_unlock(&tcon->tc_lock);
                return -EHOSTDOWN;
        }

        tcon->status = TID_IN_TCON;
        spin_unlock(&tcon->tc_lock);

        rc = ops->tree_connect(xid, tcon->ses, tcon->tree_name,
                               tcon, tcon->ses->local_nls);
        if (rc) {
                spin_lock(&tcon->tc_lock);
                if (tcon->status == TID_IN_TCON)
                        tcon->status = TID_NEED_TCON;
                spin_unlock(&tcon->tc_lock);
        } else {
                spin_lock(&tcon->tc_lock);
                if (tcon->status == TID_IN_TCON)
                        tcon->status = TID_GOOD;
                tcon->need_reconnect = false;
                spin_unlock(&tcon->tc_lock);
        }

        return rc;
}
#endif