// SPDX-License-Identifier: LGPL-2.1
/*
 *
 *   Copyright (C) International Business Machines  Corp., 2002,2008
 *   Author(s): Steve French (sfrench@us.ibm.com)
 *
 */

#include <linux/slab.h>
#include <linux/ctype.h>
#include <linux/mempool.h>
#include <linux/vmalloc.h>
#include "cifsglob.h"
#include "cifsproto.h"
#include "cifs_debug.h"
#include "smberr.h"
#include "nterr.h"
#include "cifs_unicode.h"
#include "smb2pdu.h"
#include "smb2proto.h"
#include "smb1proto.h"
#include "cifsfs.h"
#ifdef CONFIG_CIFS_DFS_UPCALL
#include "dns_resolve.h"
#include "dfs_cache.h"
#include "dfs.h"
#endif
#include "fs_context.h"
#include "cached_dir.h"

struct tcon_list {
        struct list_head entry;
        struct cifs_tcon *tcon;
};

/* The xid serves as a useful identifier for each incoming vfs request,
   in a similar way to the mid which is useful to track each sent smb,
   and CurrentXid can also provide a running counter (although it
   will eventually wrap past zero) of the total vfs operations handled
   since the cifs fs was mounted */

unsigned int
_get_xid(void)
{
        unsigned int xid;

        spin_lock(&GlobalMid_Lock);
        GlobalTotalActiveXid++;

        /* keep high water mark for number of simultaneous ops in filesystem */
        if (GlobalTotalActiveXid > GlobalMaxActiveXid)
                GlobalMaxActiveXid = GlobalTotalActiveXid;
        if (GlobalTotalActiveXid > 65000)
                cifs_dbg(FYI, "warning: more than 65000 requests active\n");
        xid = GlobalCurrentXid++;
        spin_unlock(&GlobalMid_Lock);
        return xid;
}

void
_free_xid(unsigned int xid)
{
        spin_lock(&GlobalMid_Lock);
        /* if (GlobalTotalActiveXid == 0)
                BUG(); */
        GlobalTotalActiveXid--;
        spin_unlock(&GlobalMid_Lock);
}

struct cifs_ses *
sesInfoAlloc(void)
{
        struct cifs_ses *ret_buf;

        ret_buf = kzalloc_obj(struct cifs_ses);
        if (ret_buf) {
                atomic_inc(&sesInfoAllocCount);
                spin_lock_init(&ret_buf->ses_lock);
                ret_buf->ses_status = SES_NEW;
                ++ret_buf->ses_count;
                INIT_LIST_HEAD(&ret_buf->smb_ses_list);
                INIT_LIST_HEAD(&ret_buf->tcon_list);
                mutex_init(&ret_buf->session_mutex);
                spin_lock_init(&ret_buf->iface_lock);
                INIT_LIST_HEAD(&ret_buf->iface_list);
                spin_lock_init(&ret_buf->chan_lock);
        }
        return ret_buf;
}

void
sesInfoFree(struct cifs_ses *buf_to_free)
{
        struct cifs_server_iface *iface = NULL, *niface = NULL;

        if (buf_to_free == NULL) {
                cifs_dbg(FYI, "Null buffer passed to sesInfoFree\n");
                return;
        }

        unload_nls(buf_to_free->local_nls);
        atomic_dec(&sesInfoAllocCount);
        kfree(buf_to_free->serverOS);
        kfree(buf_to_free->serverDomain);
        kfree(buf_to_free->serverNOS);
        kfree_sensitive(buf_to_free->password);
        kfree_sensitive(buf_to_free->password2);
        kfree(buf_to_free->user_name);
        kfree(buf_to_free->domainName);
        kfree(buf_to_free->dns_dom);
        kfree_sensitive(buf_to_free->auth_key.response);
        spin_lock(&buf_to_free->iface_lock);
        list_for_each_entry_safe(iface, niface, &buf_to_free->iface_list,
                                 iface_head)
                kref_put(&iface->refcount, release_iface);
        spin_unlock(&buf_to_free->iface_lock);
        kfree_sensitive(buf_to_free);
}

struct cifs_tcon *
tcon_info_alloc(bool dir_leases_enabled, enum smb3_tcon_ref_trace trace)
{
        struct cifs_tcon *ret_buf;
        static atomic_t tcon_debug_id;

        ret_buf = kzalloc_obj(*ret_buf);
        if (!ret_buf)
                return NULL;

        if (dir_leases_enabled == true) {
                ret_buf->cfids = init_cached_dirs();
                if (!ret_buf->cfids) {
                        kfree(ret_buf);
                        return NULL;
                }
        }
        /* else ret_buf->cfids is already set to NULL above */

        atomic_inc(&tconInfoAllocCount);
        ret_buf->status = TID_NEW;
        ret_buf->debug_id = atomic_inc_return(&tcon_debug_id);
        ret_buf->tc_count = 1;
        spin_lock_init(&ret_buf->tc_lock);
        INIT_LIST_HEAD(&ret_buf->openFileList);
        INIT_LIST_HEAD(&ret_buf->tcon_list);
        INIT_LIST_HEAD(&ret_buf->cifs_sb_list);
        spin_lock_init(&ret_buf->open_file_lock);
        spin_lock_init(&ret_buf->stat_lock);
        spin_lock_init(&ret_buf->sb_list_lock);
        atomic_set(&ret_buf->num_local_opens, 0);
        atomic_set(&ret_buf->num_remote_opens, 0);
        ret_buf->stats_from_time = ktime_get_real_seconds();
#ifdef CONFIG_CIFS_FSCACHE
        mutex_init(&ret_buf->fscache_lock);
#endif
        trace_smb3_tcon_ref(ret_buf->debug_id, ret_buf->tc_count, trace);
#ifdef CONFIG_CIFS_DFS_UPCALL
        INIT_LIST_HEAD(&ret_buf->dfs_ses_list);
#endif
        INIT_LIST_HEAD(&ret_buf->pending_opens);
        INIT_DELAYED_WORK(&ret_buf->query_interfaces,
                          smb2_query_server_interfaces);
#ifdef CONFIG_CIFS_DFS_UPCALL
        INIT_DELAYED_WORK(&ret_buf->dfs_cache_work, dfs_cache_refresh);
#endif

        return ret_buf;
}

void
tconInfoFree(struct cifs_tcon *tcon, enum smb3_tcon_ref_trace trace)
{
        if (tcon == NULL) {
                cifs_dbg(FYI, "Null buffer passed to tconInfoFree\n");
                return;
        }
        trace_smb3_tcon_ref(tcon->debug_id, tcon->tc_count, trace);
        free_cached_dirs(tcon->cfids);
        atomic_dec(&tconInfoAllocCount);
        kfree(tcon->nativeFileSystem);
        kfree_sensitive(tcon->password);
        kfree(tcon->origin_fullpath);
        kfree(tcon);
}

void *
cifs_buf_get(void)
{
        void *ret_buf = NULL;
        /*
         * SMB2 header is bigger than CIFS one - no problems to clean some
         * more bytes for CIFS.
         */
        size_t buf_size = sizeof(struct smb2_hdr);

        /*
         * We could use negotiated size instead of max_msgsize -
         * but it may be more efficient to always alloc same size
         * albeit slightly larger than necessary and maxbuffersize
         * defaults to this and can not be bigger.
         */
        ret_buf = mempool_alloc(cifs_req_poolp, GFP_NOFS);

        /* clear the first few header bytes */
        /* for most paths, more is cleared in header_assemble */
        memset(ret_buf, 0, buf_size + 3);
        atomic_inc(&buf_alloc_count);
#ifdef CONFIG_CIFS_STATS2
        atomic_inc(&total_buf_alloc_count);
#endif /* CONFIG_CIFS_STATS2 */

        return ret_buf;
}

void
cifs_buf_release(void *buf_to_free)
{
        if (buf_to_free == NULL) {
                /* cifs_dbg(FYI, "Null buffer passed to cifs_buf_release\n");*/
                return;
        }
        mempool_free(buf_to_free, cifs_req_poolp);

        atomic_dec(&buf_alloc_count);
        return;
}

void *
cifs_small_buf_get(void)
{
        void *ret_buf = NULL;

/* We could use negotiated size instead of max_msgsize -
   but it may be more efficient to always alloc same size
   albeit slightly larger than necessary and maxbuffersize
   defaults to this and can not be bigger */
        ret_buf = mempool_alloc(cifs_sm_req_poolp, GFP_NOFS);
        /* No need to clear memory here, cleared in header assemble */
        atomic_inc(&small_buf_alloc_count);
#ifdef CONFIG_CIFS_STATS2
        atomic_inc(&total_small_buf_alloc_count);
#endif /* CONFIG_CIFS_STATS2 */

        return ret_buf;
}

void
cifs_small_buf_release(void *buf_to_free)
{

        if (buf_to_free == NULL) {
                cifs_dbg(FYI, "Null buffer passed to cifs_small_buf_release\n");
                return;
        }
        mempool_free(buf_to_free, cifs_sm_req_poolp);

        atomic_dec(&small_buf_alloc_count);
        return;
}

void
free_rsp_buf(int resp_buftype, void *rsp)
{
        if (resp_buftype == CIFS_SMALL_BUFFER)
                cifs_small_buf_release(rsp);
        else if (resp_buftype == CIFS_LARGE_BUFFER)
                cifs_buf_release(rsp);
}

void
dump_smb(void *buf, int smb_buf_length)
{
        if (traceSMB == 0)
                return;

        print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_NONE, 8, 2, buf,
                       smb_buf_length, true);
}

void
cifs_autodisable_serverino(struct cifs_sb_info *cifs_sb)
{
        unsigned int sbflags = cifs_sb_flags(cifs_sb);

        if (sbflags & CIFS_MOUNT_SERVER_INUM) {
                struct cifs_tcon *tcon = NULL;

                if (cifs_sb->master_tlink)
                        tcon = cifs_sb_master_tcon(cifs_sb);

                atomic_andnot(CIFS_MOUNT_SERVER_INUM, &cifs_sb->mnt_cifs_flags);
                cifs_sb->mnt_cifs_serverino_autodisabled = true;
                cifs_dbg(VFS, "Autodisabling the use of server inode numbers on %s\n",
                         tcon ? tcon->tree_name : "new server");
                cifs_dbg(VFS, "The server doesn't seem to support them properly or the files might be on different servers (DFS)\n");
                cifs_dbg(VFS, "Hardlinks will not be recognized on this mount. Consider mounting with the \"noserverino\" option to silence this message.\n");

        }
}

void cifs_set_oplock_level(struct cifsInodeInfo *cinode, __u32 oplock)
{
        oplock &= 0xF;

        if (oplock == OPLOCK_EXCLUSIVE) {
                cinode->oplock = CIFS_CACHE_WRITE_FLG | CIFS_CACHE_READ_FLG;
                cifs_dbg(FYI, "Exclusive Oplock granted on inode %p\n",
                         &cinode->netfs.inode);
        } else if (oplock == OPLOCK_READ) {
                cinode->oplock = CIFS_CACHE_READ_FLG;
                cifs_dbg(FYI, "Level II Oplock granted on inode %p\n",
                         &cinode->netfs.inode);
        } else
                cinode->oplock = 0;
}

/*
 * We wait for oplock breaks to be processed before we attempt to perform
 * writes.
 */
int cifs_get_writer(struct cifsInodeInfo *cinode)
{
        int rc;

start:
        rc = wait_on_bit(&cinode->flags, CIFS_INODE_PENDING_OPLOCK_BREAK,
                         TASK_KILLABLE);
        if (rc)
                return rc;

        spin_lock(&cinode->writers_lock);
        if (!cinode->writers)
                set_bit(CIFS_INODE_PENDING_WRITERS, &cinode->flags);
        cinode->writers++;
        /* Check to see if we have started servicing an oplock break */
        if (test_bit(CIFS_INODE_PENDING_OPLOCK_BREAK, &cinode->flags)) {
                cinode->writers--;
                if (cinode->writers == 0) {
                        clear_bit(CIFS_INODE_PENDING_WRITERS, &cinode->flags);
                        wake_up_bit(&cinode->flags, CIFS_INODE_PENDING_WRITERS);
                }
                spin_unlock(&cinode->writers_lock);
                goto start;
        }
        spin_unlock(&cinode->writers_lock);
        return 0;
}

void cifs_put_writer(struct cifsInodeInfo *cinode)
{
        spin_lock(&cinode->writers_lock);
        cinode->writers--;
        if (cinode->writers == 0) {
                clear_bit(CIFS_INODE_PENDING_WRITERS, &cinode->flags);
                wake_up_bit(&cinode->flags, CIFS_INODE_PENDING_WRITERS);
        }
        spin_unlock(&cinode->writers_lock);
}

/**
 * cifs_queue_oplock_break - queue the oplock break handler for cfile
 * @cfile: The file to break the oplock on
 *
 * This function is called from the demultiplex thread when it
 * receives an oplock break for @cfile.
 *
 * Assumes the tcon->open_file_lock is held.
 * Assumes cfile->file_info_lock is NOT held.
 */
void cifs_queue_oplock_break(struct cifsFileInfo *cfile)
{
        /*
         * Bump the handle refcount now while we hold the
         * open_file_lock to enforce the validity of it for the oplock
         * break handler. The matching put is done at the end of the
         * handler.
         */
        cifsFileInfo_get(cfile);

        queue_work(cifsoplockd_wq, &cfile->oplock_break);
}

void cifs_done_oplock_break(struct cifsInodeInfo *cinode)
{
        clear_bit(CIFS_INODE_PENDING_OPLOCK_BREAK, &cinode->flags);
        wake_up_bit(&cinode->flags, CIFS_INODE_PENDING_OPLOCK_BREAK);
}

bool
backup_cred(struct cifs_sb_info *cifs_sb)
{
        unsigned int sbflags = cifs_sb_flags(cifs_sb);

        if (sbflags & CIFS_MOUNT_CIFS_BACKUPUID) {
                if (uid_eq(cifs_sb->ctx->backupuid, current_fsuid()))
                        return true;
        }
        if (sbflags & CIFS_MOUNT_CIFS_BACKUPGID) {
                if (in_group_p(cifs_sb->ctx->backupgid))
                        return true;
        }

        return false;
}

void
cifs_del_pending_open(struct cifs_pending_open *open)
{
        spin_lock(&tlink_tcon(open->tlink)->open_file_lock);
        list_del(&open->olist);
        spin_unlock(&tlink_tcon(open->tlink)->open_file_lock);
}

void
cifs_add_pending_open_locked(struct cifs_fid *fid, struct tcon_link *tlink,
                             struct cifs_pending_open *open)
{
        memcpy(open->lease_key, fid->lease_key, SMB2_LEASE_KEY_SIZE);
        open->oplock = CIFS_OPLOCK_NO_CHANGE;
        open->tlink = tlink;
        fid->pending_open = open;
        list_add_tail(&open->olist, &tlink_tcon(tlink)->pending_opens);
}

void
cifs_add_pending_open(struct cifs_fid *fid, struct tcon_link *tlink,
                      struct cifs_pending_open *open)
{
        spin_lock(&tlink_tcon(tlink)->open_file_lock);
        cifs_add_pending_open_locked(fid, tlink, open);
        spin_unlock(&tlink_tcon(open->tlink)->open_file_lock);
}

/*
 * Critical section which runs after acquiring deferred_lock.
 * As there is no reference count on cifs_deferred_close, pdclose
 * should not be used outside deferred_lock.
 */
bool
cifs_is_deferred_close(struct cifsFileInfo *cfile, struct cifs_deferred_close **pdclose)
{
        struct cifs_deferred_close *dclose;

        list_for_each_entry(dclose, &CIFS_I(d_inode(cfile->dentry))->deferred_closes, dlist) {
                if ((dclose->netfid == cfile->fid.netfid) &&
                        (dclose->persistent_fid == cfile->fid.persistent_fid) &&
                        (dclose->volatile_fid == cfile->fid.volatile_fid)) {
                        *pdclose = dclose;
                        return true;
                }
        }
        return false;
}

/*
 * Critical section which runs after acquiring deferred_lock.
 */
void
cifs_add_deferred_close(struct cifsFileInfo *cfile, struct cifs_deferred_close *dclose)
{
        bool is_deferred = false;
        struct cifs_deferred_close *pdclose;

        is_deferred = cifs_is_deferred_close(cfile, &pdclose);
        if (is_deferred) {
                kfree(dclose);
                return;
        }

        dclose->tlink = cfile->tlink;
        dclose->netfid = cfile->fid.netfid;
        dclose->persistent_fid = cfile->fid.persistent_fid;
        dclose->volatile_fid = cfile->fid.volatile_fid;
        list_add_tail(&dclose->dlist, &CIFS_I(d_inode(cfile->dentry))->deferred_closes);
}

/*
 * Critical section which runs after acquiring deferred_lock.
 */
void
cifs_del_deferred_close(struct cifsFileInfo *cfile)
{
        bool is_deferred = false;
        struct cifs_deferred_close *dclose;

        is_deferred = cifs_is_deferred_close(cfile, &dclose);
        if (!is_deferred)
                return;
        list_del(&dclose->dlist);
        kfree(dclose);
}

void
cifs_close_deferred_file(struct cifsInodeInfo *cifs_inode)
{
        struct cifsFileInfo *cfile = NULL;
        struct file_list *tmp_list, *tmp_next_list;
        LIST_HEAD(file_head);

        if (cifs_inode == NULL)
                return;

        spin_lock(&cifs_inode->open_file_lock);
        list_for_each_entry(cfile, &cifs_inode->openFileList, flist) {
                if (delayed_work_pending(&cfile->deferred)) {
                        if (cancel_delayed_work(&cfile->deferred)) {
                                spin_lock(&cifs_inode->deferred_lock);
                                cifs_del_deferred_close(cfile);
                                spin_unlock(&cifs_inode->deferred_lock);

                                tmp_list = kmalloc_obj(struct file_list,
                                                       GFP_ATOMIC);
                                if (tmp_list == NULL)
                                        break;
                                tmp_list->cfile = cfile;
                                list_add_tail(&tmp_list->list, &file_head);
                        }
                }
        }
        spin_unlock(&cifs_inode->open_file_lock);

        list_for_each_entry_safe(tmp_list, tmp_next_list, &file_head, list) {
                _cifsFileInfo_put(tmp_list->cfile, false, false);
                list_del(&tmp_list->list);
                kfree(tmp_list);
        }
}

void
cifs_close_all_deferred_files(struct cifs_tcon *tcon)
{
        struct cifsFileInfo *cfile;
        struct file_list *tmp_list, *tmp_next_list;
        LIST_HEAD(file_head);

        spin_lock(&tcon->open_file_lock);
        list_for_each_entry(cfile, &tcon->openFileList, tlist) {
                if (delayed_work_pending(&cfile->deferred)) {
                        if (cancel_delayed_work(&cfile->deferred)) {
                                spin_lock(&CIFS_I(d_inode(cfile->dentry))->deferred_lock);
                                cifs_del_deferred_close(cfile);
                                spin_unlock(&CIFS_I(d_inode(cfile->dentry))->deferred_lock);

                                tmp_list = kmalloc_obj(struct file_list,
                                                       GFP_ATOMIC);
                                if (tmp_list == NULL)
                                        break;
                                tmp_list->cfile = cfile;
                                list_add_tail(&tmp_list->list, &file_head);
                        }
                }
        }
        spin_unlock(&tcon->open_file_lock);

        list_for_each_entry_safe(tmp_list, tmp_next_list, &file_head, list) {
                _cifsFileInfo_put(tmp_list->cfile, true, false);
                list_del(&tmp_list->list);
                kfree(tmp_list);
        }
}

void cifs_close_all_deferred_files_sb(struct cifs_sb_info *cifs_sb)
{
        struct rb_root *root = &cifs_sb->tlink_tree;
        struct rb_node *node;
        struct cifs_tcon *tcon;
        struct tcon_link *tlink;
        struct tcon_list *tmp_list, *q;
        LIST_HEAD(tcon_head);

        spin_lock(&cifs_sb->tlink_tree_lock);
        for (node = rb_first(root); node; node = rb_next(node)) {
                tlink = rb_entry(node, struct tcon_link, tl_rbnode);
                tcon = tlink_tcon(tlink);
                if (IS_ERR(tcon))
                        continue;
                tmp_list = kmalloc_obj(struct tcon_list, GFP_ATOMIC);
                if (tmp_list == NULL)
                        break;
                tmp_list->tcon = tcon;
                /* Take a reference on tcon to prevent it from being freed */
                spin_lock(&tcon->tc_lock);
                ++tcon->tc_count;
                trace_smb3_tcon_ref(tcon->debug_id, tcon->tc_count,
                                    netfs_trace_tcon_ref_get_close_defer_files);
                spin_unlock(&tcon->tc_lock);
                list_add_tail(&tmp_list->entry, &tcon_head);
        }
        spin_unlock(&cifs_sb->tlink_tree_lock);

        list_for_each_entry_safe(tmp_list, q, &tcon_head, entry) {
                cifs_close_all_deferred_files(tmp_list->tcon);
                list_del(&tmp_list->entry);
                cifs_put_tcon(tmp_list->tcon, netfs_trace_tcon_ref_put_close_defer_files);
                kfree(tmp_list);
        }
}

void cifs_close_deferred_file_under_dentry(struct cifs_tcon *tcon,
                                           struct dentry *dentry)
{
        struct file_list *tmp_list, *tmp_next_list;
        struct cifsFileInfo *cfile;
        LIST_HEAD(file_head);

        spin_lock(&tcon->open_file_lock);
        list_for_each_entry(cfile, &tcon->openFileList, tlist) {
                if ((cfile->dentry == dentry) &&
                    delayed_work_pending(&cfile->deferred) &&
                    cancel_delayed_work(&cfile->deferred)) {
                        spin_lock(&CIFS_I(d_inode(cfile->dentry))->deferred_lock);
                        cifs_del_deferred_close(cfile);
                        spin_unlock(&CIFS_I(d_inode(cfile->dentry))->deferred_lock);

                        tmp_list = kmalloc_obj(struct file_list, GFP_ATOMIC);
                        if (tmp_list == NULL)
                                break;
                        tmp_list->cfile = cfile;
                        list_add_tail(&tmp_list->list, &file_head);
                }
        }
        spin_unlock(&tcon->open_file_lock);

        list_for_each_entry_safe(tmp_list, tmp_next_list, &file_head, list) {
                _cifsFileInfo_put(tmp_list->cfile, true, false);
                list_del(&tmp_list->list);
                kfree(tmp_list);
        }
}

/*
 * If a dentry has been deleted, all corresponding open handles should know that
 * so that we do not defer close them.
 */
void cifs_mark_open_handles_for_deleted_file(struct inode *inode,
                                             const char *path)
{
        struct cifsFileInfo *cfile;
        void *page;
        const char *full_path;
        struct cifsInodeInfo *cinode = CIFS_I(inode);

        page = alloc_dentry_path();
        spin_lock(&cinode->open_file_lock);

        /*
         * note: we need to construct path from dentry and compare only if the
         * inode has any hardlinks. When number of hardlinks is 1, we can just
         * mark all open handles since they are going to be from the same file.
         */
        if (inode->i_nlink > 1) {
                list_for_each_entry(cfile, &cinode->openFileList, flist) {
                        full_path = build_path_from_dentry(cfile->dentry, page);
                        if (!IS_ERR(full_path) && strcmp(full_path, path) == 0)
                                cfile->status_file_deleted = true;
                }
        } else {
                list_for_each_entry(cfile, &cinode->openFileList, flist)
                        cfile->status_file_deleted = true;
        }
        spin_unlock(&cinode->open_file_lock);
        free_dentry_path(page);
}

/* parses DFS referral V3 structure
 * caller is responsible for freeing target_nodes
 * returns:
 * - on success - 0
 * - on failure - errno
 */
int
parse_dfs_referrals(struct get_dfs_referral_rsp *rsp, u32 rsp_size,
                    unsigned int *num_of_nodes,
                    struct dfs_info3_param **target_nodes,
                    const struct nls_table *nls_codepage, int remap,
                    const char *searchName, bool is_unicode)
{
        int i, rc = 0;
        char *data_end;
        struct dfs_referral_level_3 *ref;

        if (rsp_size < sizeof(*rsp)) {
                cifs_dbg(VFS | ONCE,
                         "%s: header is malformed (size is %u, must be %zu)\n",
                         __func__, rsp_size, sizeof(*rsp));
                rc = -EINVAL;
                goto parse_DFS_referrals_exit;
        }

        *num_of_nodes = le16_to_cpu(rsp->NumberOfReferrals);

        if (*num_of_nodes < 1) {
                cifs_dbg(VFS | ONCE, "%s: [path=%s] num_referrals must be at least > 0, but we got %d\n",
                         __func__, searchName, *num_of_nodes);
                rc = -ENOENT;
                goto parse_DFS_referrals_exit;
        }

        if (sizeof(*rsp) + *num_of_nodes * sizeof(REFERRAL3) > rsp_size) {
                cifs_dbg(VFS | ONCE,
                         "%s: malformed buffer (size is %u, must be at least %zu)\n",
                         __func__, rsp_size,
                         sizeof(*rsp) + *num_of_nodes * sizeof(REFERRAL3));
                rc = -EINVAL;
                goto parse_DFS_referrals_exit;
        }

        ref = (struct dfs_referral_level_3 *) &(rsp->referrals);
        if (ref->VersionNumber != cpu_to_le16(3)) {
                cifs_dbg(VFS, "Referrals of V%d version are not supported, should be V3\n",
                         le16_to_cpu(ref->VersionNumber));
                rc = -EINVAL;
                goto parse_DFS_referrals_exit;
        }

        /* get the upper boundary of the resp buffer */
        data_end = (char *)rsp + rsp_size;

        cifs_dbg(FYI, "num_referrals: %d dfs flags: 0x%x ...\n",
                 *num_of_nodes, le32_to_cpu(rsp->DFSFlags));

        *target_nodes = kzalloc_objs(struct dfs_info3_param, *num_of_nodes);
        if (*target_nodes == NULL) {
                rc = -ENOMEM;
                goto parse_DFS_referrals_exit;
        }

        /* collect necessary data from referrals */
        for (i = 0; i < *num_of_nodes; i++) {
                char *temp;
                int max_len;
                struct dfs_info3_param *node = (*target_nodes)+i;

                node->flags = le32_to_cpu(rsp->DFSFlags);
                if (is_unicode) {
                        __le16 *tmp = kmalloc(strlen(searchName)*2 + 2,
                                                GFP_KERNEL);
                        if (tmp == NULL) {
                                rc = -ENOMEM;
                                goto parse_DFS_referrals_exit;
                        }
                        cifsConvertToUTF16((__le16 *) tmp, searchName,
                                           PATH_MAX, nls_codepage, remap);
                        node->path_consumed = cifs_utf16_bytes(tmp,
                                        le16_to_cpu(rsp->PathConsumed),
                                        nls_codepage);
                        kfree(tmp);
                } else
                        node->path_consumed = le16_to_cpu(rsp->PathConsumed);

                node->server_type = le16_to_cpu(ref->ServerType);
                node->ref_flag = le16_to_cpu(ref->ReferralEntryFlags);

                /* copy DfsPath */
                temp = (char *)ref + le16_to_cpu(ref->DfsPathOffset);
                max_len = data_end - temp;
                node->path_name = cifs_strndup_from_utf16(temp, max_len,
                                                is_unicode, nls_codepage);
                if (!node->path_name) {
                        rc = -ENOMEM;
                        goto parse_DFS_referrals_exit;
                }

                /* copy link target UNC */
                temp = (char *)ref + le16_to_cpu(ref->NetworkAddressOffset);
                max_len = data_end - temp;
                node->node_name = cifs_strndup_from_utf16(temp, max_len,
                                                is_unicode, nls_codepage);
                if (!node->node_name) {
                        rc = -ENOMEM;
                        goto parse_DFS_referrals_exit;
                }

                node->ttl = le32_to_cpu(ref->TimeToLive);

                ref++;
        }

parse_DFS_referrals_exit:
        if (rc) {
                free_dfs_info_array(*target_nodes, *num_of_nodes);
                *target_nodes = NULL;
                *num_of_nodes = 0;
        }
        return rc;
}

/**
 * cifs_alloc_hash - allocate hash and hash context together
 * @name: The name of the crypto hash algo
 * @sdesc: SHASH descriptor where to put the pointer to the hash TFM
 *
 * The caller has to make sure @sdesc is initialized to either NULL or
 * a valid context. It can be freed via cifs_free_hash().
 */
int
cifs_alloc_hash(const char *name, struct shash_desc **sdesc)
{
        int rc = 0;
        struct crypto_shash *alg = NULL;

        if (*sdesc)
                return 0;

        alg = crypto_alloc_shash(name, 0, 0);
        if (IS_ERR(alg)) {
                cifs_dbg(VFS, "Could not allocate shash TFM '%s'\n", name);
                rc = PTR_ERR(alg);
                *sdesc = NULL;
                return rc;
        }

        *sdesc = kmalloc(sizeof(struct shash_desc) + crypto_shash_descsize(alg), GFP_KERNEL);
        if (*sdesc == NULL) {
                cifs_dbg(VFS, "no memory left to allocate shash TFM '%s'\n", name);
                crypto_free_shash(alg);
                return -ENOMEM;
        }

        (*sdesc)->tfm = alg;
        return 0;
}

/**
 * cifs_free_hash - free hash and hash context together
 * @sdesc: Where to find the pointer to the hash TFM
 *
 * Freeing a NULL descriptor is safe.
 */
void
cifs_free_hash(struct shash_desc **sdesc)
{
        if (unlikely(!sdesc) || !*sdesc)
                return;

        if ((*sdesc)->tfm) {
                crypto_free_shash((*sdesc)->tfm);
                (*sdesc)->tfm = NULL;
        }

        kfree_sensitive(*sdesc);
        *sdesc = NULL;
}

void extract_unc_hostname(const char *unc, const char **h, size_t *len)
{
        const char *end;

        /* skip initial slashes */
        while (*unc && (*unc == '\\' || *unc == '/'))
                unc++;

        end = unc;

        while (*end && !(*end == '\\' || *end == '/'))
                end++;

        *h = unc;
        *len = end - unc;
}

/**
 * copy_path_name - copy src path to dst, possibly truncating
 * @dst: The destination buffer
 * @src: The source name
 *
 * returns number of bytes written (including trailing nul)
 */
int copy_path_name(char *dst, const char *src)
{
        int name_len;

        /*
         * PATH_MAX includes nul, so if strlen(src) >= PATH_MAX it
         * will truncate and strlen(dst) will be PATH_MAX-1
         */
        name_len = strscpy(dst, src, PATH_MAX);
        if (WARN_ON_ONCE(name_len < 0))
                name_len = PATH_MAX-1;

        /* we count the trailing nul */
        name_len++;
        return name_len;
}

struct super_cb_data {
        void *data;
        struct super_block *sb;
};

static void tcon_super_cb(struct super_block *sb, void *arg)
{
        struct super_cb_data *sd = arg;
        struct cifs_sb_info *cifs_sb;
        struct cifs_tcon *t1 = sd->data, *t2;

        if (sd->sb)
                return;

        cifs_sb = CIFS_SB(sb);
        t2 = cifs_sb_master_tcon(cifs_sb);

        spin_lock(&t2->tc_lock);
        if ((t1->ses == t2->ses ||
             t1->ses->dfs_root_ses == t2->ses->dfs_root_ses) &&
            t1->ses->server == t2->ses->server &&
            t2->origin_fullpath &&
            dfs_src_pathname_equal(t2->origin_fullpath, t1->origin_fullpath))
                sd->sb = sb;
        spin_unlock(&t2->tc_lock);
}

static struct super_block *__cifs_get_super(void (*f)(struct super_block *, void *),
                                            void *data)
{
        struct super_cb_data sd = {
                .data = data,
                .sb = NULL,
        };
        struct file_system_type **fs_type = (struct file_system_type *[]) {
                &cifs_fs_type, &smb3_fs_type, NULL,
        };

        for (; *fs_type; fs_type++) {
                iterate_supers_type(*fs_type, f, &sd);
                if (sd.sb) {
                        /*
                         * Grab an active reference in order to prevent automounts (DFS links)
                         * of expiring and then freeing up our cifs superblock pointer while
                         * we're doing failover.
                         */
                        cifs_sb_active(sd.sb);
                        return sd.sb;
                }
        }
        pr_warn_once("%s: could not find dfs superblock\n", __func__);
        return ERR_PTR(-EINVAL);
}

static void __cifs_put_super(struct super_block *sb)
{
        if (!IS_ERR_OR_NULL(sb))
                cifs_sb_deactive(sb);
}

struct super_block *cifs_get_dfs_tcon_super(struct cifs_tcon *tcon)
{
        spin_lock(&tcon->tc_lock);
        if (!tcon->origin_fullpath) {
                spin_unlock(&tcon->tc_lock);
                return ERR_PTR(-ENOENT);
        }
        spin_unlock(&tcon->tc_lock);
        return __cifs_get_super(tcon_super_cb, tcon);
}

void cifs_put_tcp_super(struct super_block *sb)
{
        __cifs_put_super(sb);
}

#ifdef CONFIG_CIFS_DFS_UPCALL
int match_target_ip(struct TCP_Server_Info *server,
                    const char *host, size_t hostlen,
                    bool *result)
{
        struct sockaddr_storage ss;
        int rc;

        cifs_dbg(FYI, "%s: hostname=%.*s\n", __func__, (int)hostlen, host);

        *result = false;

        rc = dns_resolve_name(server->dns_dom, host, hostlen,
                              (struct sockaddr *)&ss);
        if (rc < 0)
                return rc;

        spin_lock(&server->srv_lock);
        *result = cifs_match_ipaddr((struct sockaddr *)&server->dstaddr, (struct sockaddr *)&ss);
        spin_unlock(&server->srv_lock);
        cifs_dbg(FYI, "%s: ip addresses matched: %s\n", __func__, str_yes_no(*result));
        return 0;
}

int cifs_update_super_prepath(struct cifs_sb_info *cifs_sb, char *prefix)
{
        int rc;

        kfree(cifs_sb->prepath);
        cifs_sb->prepath = NULL;

        if (prefix && *prefix) {
                cifs_sb->prepath = cifs_sanitize_prepath(prefix, GFP_ATOMIC);
                if (IS_ERR(cifs_sb->prepath)) {
                        rc = PTR_ERR(cifs_sb->prepath);
                        cifs_sb->prepath = NULL;
                        return rc;
                }
                if (cifs_sb->prepath)
                        convert_delimiter(cifs_sb->prepath, CIFS_DIR_SEP(cifs_sb));
        }

        atomic_or(CIFS_MOUNT_USE_PREFIX_PATH, &cifs_sb->mnt_cifs_flags);
        return 0;
}

/*
 * Handle weird Windows SMB server behaviour. It responds with
 * STATUS_OBJECT_NAME_INVALID code to SMB2 QUERY_INFO request for
 * "\<server>\<dfsname>\<linkpath>" DFS reference, where <dfsname> contains
 * non-ASCII unicode symbols.
 */
int cifs_inval_name_dfs_link_error(const unsigned int xid,
                                   struct cifs_tcon *tcon,
                                   struct cifs_sb_info *cifs_sb,
                                   const char *full_path,
                                   bool *islink)
{
        struct TCP_Server_Info *server = tcon->ses->server;
        struct cifs_ses *ses = tcon->ses;
        size_t len;
        char *path;
        char *ref_path;

        *islink = false;

        /*
         * Fast path - skip check when @full_path doesn't have a prefix path to
         * look up or tcon is not DFS.
         */
        if (strlen(full_path) < 2 || !cifs_sb ||
            (cifs_sb_flags(cifs_sb) & CIFS_MOUNT_NO_DFS) ||
            !is_tcon_dfs(tcon))
                return 0;

        spin_lock(&server->srv_lock);
        if (!server->leaf_fullpath) {
                spin_unlock(&server->srv_lock);
                return 0;
        }
        spin_unlock(&server->srv_lock);

        /*
         * Slow path - tcon is DFS and @full_path has prefix path, so attempt
         * to get a referral to figure out whether it is an DFS link.
         */
        len = strnlen(tcon->tree_name, MAX_TREE_SIZE + 1) + strlen(full_path) + 1;
        path = kmalloc(len, GFP_KERNEL);
        if (!path)
                return -ENOMEM;

        scnprintf(path, len, "%s%s", tcon->tree_name, full_path);
        ref_path = dfs_cache_canonical_path(path + 1, cifs_sb->local_nls,
                                            cifs_remap(cifs_sb));
        kfree(path);

        if (IS_ERR(ref_path)) {
                if (PTR_ERR(ref_path) != -EINVAL)
                        return PTR_ERR(ref_path);
        } else {
                struct dfs_info3_param *refs = NULL;
                int num_refs = 0;

                /*
                 * XXX: we are not using dfs_cache_find() here because we might
                 * end up filling all the DFS cache and thus potentially
                 * removing cached DFS targets that the client would eventually
                 * need during failover.
                 */
                ses = CIFS_DFS_ROOT_SES(ses);
                if (ses->server->ops->get_dfs_refer &&
                    !ses->server->ops->get_dfs_refer(xid, ses, ref_path, &refs,
                                                     &num_refs, cifs_sb->local_nls,
                                                     cifs_remap(cifs_sb)))
                        *islink = refs[0].server_type == DFS_TYPE_LINK;
                free_dfs_info_array(refs, num_refs);
                kfree(ref_path);
        }
        return 0;
}
#endif

int cifs_wait_for_server_reconnect(struct TCP_Server_Info *server, bool retry)
{
        int timeout = 10;
        int rc;

        spin_lock(&server->srv_lock);
        if (server->tcpStatus != CifsNeedReconnect) {
                spin_unlock(&server->srv_lock);
                return 0;
        }
        timeout *= server->nr_targets;
        spin_unlock(&server->srv_lock);

        /*
         * Give demultiplex thread up to 10 seconds to each target available for
         * reconnect -- should be greater than cifs socket timeout which is 7
         * seconds.
         *
         * On "soft" mounts we wait once. Hard mounts keep retrying until
         * process is killed or server comes back on-line.
         */
        do {
                rc = wait_event_interruptible_timeout(server->response_q,
                                                      (server->tcpStatus != CifsNeedReconnect),
                                                      timeout * HZ);
                if (rc < 0) {
                        cifs_dbg(FYI, "%s: aborting reconnect due to received signal\n",
                                 __func__);
                        return -ERESTARTSYS;
                }

                /* are we still trying to reconnect? */
                spin_lock(&server->srv_lock);
                if (server->tcpStatus != CifsNeedReconnect) {
                        spin_unlock(&server->srv_lock);
                        return 0;
                }
                spin_unlock(&server->srv_lock);
        } while (retry);

        cifs_dbg(FYI, "%s: gave up waiting on reconnect\n", __func__);
        return -EHOSTDOWN;
}