// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *   Copyright (C) 2016 Namjae Jeon <namjae.jeon@protocolfreedom.org>
 *   Copyright (C) 2018 Samsung Electronics Co., Ltd.
 */

#include <linux/mutex.h>
#include <linux/freezer.h>
#include <linux/module.h>

#include "server.h"
#include "smb_common.h"
#include "mgmt/ksmbd_ida.h"
#include "connection.h"
#include "compress.h"
#include "transport_tcp.h"
#include "transport_rdma.h"
#include "misc.h"

static DEFINE_MUTEX(init_lock);

static struct ksmbd_conn_ops default_conn_ops;

DEFINE_HASHTABLE(conn_list, CONN_HASH_BITS);
DECLARE_RWSEM(conn_list_lock);

#ifdef CONFIG_PROC_FS
static struct proc_dir_entry *proc_clients;

static int proc_show_clients(struct seq_file *m, void *v)
{
        struct ksmbd_conn *conn;
        struct timespec64 now, t;
        int i;

        seq_printf(m, "#%-20s %-10s %-10s %-10s %-10s %-10s\n",
                        "<name>", "<dialect>", "<credits>", "<open files>",
                        "<requests>", "<last active>");

        down_read(&conn_list_lock);
        hash_for_each(conn_list, i, conn, hlist) {
                jiffies_to_timespec64(jiffies - conn->last_active, &t);
                ktime_get_real_ts64(&now);
                t = timespec64_sub(now, t);
#if IS_ENABLED(CONFIG_IPV6)
                if (!conn->inet_addr)
                        seq_printf(m, "%-20pI6c", &conn->inet6_addr);
                else
#endif
                        seq_printf(m, "%-20pI4", &conn->inet_addr);
                seq_printf(m, "   0x%-10x %-10u %-12d %-10d %ptT\n",
                           conn->dialect,
                           conn->total_credits,
                           atomic_read(&conn->stats.open_files_count),
                           atomic_read(&conn->req_running),
                           &t);
        }
        up_read(&conn_list_lock);
        return 0;
}

static int create_proc_clients(void)
{
        proc_clients = ksmbd_proc_create("clients",
                                         proc_show_clients, NULL);
        if (!proc_clients)
                return -ENOMEM;
        return 0;
}

static void delete_proc_clients(void)
{
        if (proc_clients) {
                proc_remove(proc_clients);
                proc_clients = NULL;
        }
}
#else
static int create_proc_clients(void) { return 0; }
static void delete_proc_clients(void) {}
#endif

static struct workqueue_struct *ksmbd_conn_wq;

int ksmbd_conn_wq_init(void)
{
        ksmbd_conn_wq = alloc_workqueue("ksmbd-conn-release",
                                        WQ_UNBOUND | WQ_MEM_RECLAIM, 0);
        if (!ksmbd_conn_wq)
                return -ENOMEM;
        return 0;
}

void ksmbd_conn_wq_destroy(void)
{
        if (ksmbd_conn_wq) {
                destroy_workqueue(ksmbd_conn_wq);
                ksmbd_conn_wq = NULL;
        }
}

/*
 * __ksmbd_conn_release_work() - perform the final, once-per-struct cleanup
 * of a ksmbd_conn whose refcount has just dropped to zero.
 *
 * This is the common release path used by ksmbd_conn_put() for the embedded
 * state that outlives the connection thread: async_ida and the attached
 * transport (which owns the socket and iov for TCP).  Called from a workqueue
 * so that sleep-allowed teardown (sock_release -> tcp_close ->
 * lock_sock_nested) never runs from an RCU softirq callback (free_opinfo_rcu)
 * or any other non-sleeping putter context.
 */
static void __ksmbd_conn_release_work(struct work_struct *work)
{
        struct ksmbd_conn *conn =
                container_of(work, struct ksmbd_conn, release_work);

        ida_destroy(&conn->async_ida);
        conn->transport->ops->free_transport(conn->transport);
        kfree(conn);
}

/**
 * ksmbd_conn_get() - take a reference on @conn and return it.
 *
 * @conn: connection instance to get a reference to
 *
 * Returns @conn unchanged so callers can write
 * "fp->conn = ksmbd_conn_get(work->conn);" in one expression.  Returns NULL
 * if @conn is NULL.
 */
struct ksmbd_conn *ksmbd_conn_get(struct ksmbd_conn *conn)
{
        if (!conn)
                return NULL;

        atomic_inc(&conn->refcnt);
        return conn;
}

/**
 * ksmbd_conn_put() - drop a reference and, if it was the last, queue the
 * release onto ksmbd_conn_wq so it runs from process context.
 *
 * @conn: connection instance to put a reference to
 *
 * Callable from any context including RCU softirq callbacks and non-sleeping
 * locks; the actual release is deferred to the workqueue.  ksmbd_conn_wq is
 * created in ksmbd_server_init() before any conn can be allocated and is
 * destroyed in ksmbd_server_exit() after rcu_barrier(), so it is always
 * non-NULL while a conn reference is held.
 */
void ksmbd_conn_put(struct ksmbd_conn *conn)
{
        if (!conn)
                return;

        if (atomic_dec_and_test(&conn->refcnt))
                queue_work(ksmbd_conn_wq, &conn->release_work);
}

/**
 * ksmbd_conn_free() - free resources of the connection instance
 *
 * @conn:       connection instance to be cleaned up
 *
 * During the thread termination, the corresponding conn instance
 * resources(sock/memory) are released and finally the conn object is freed.
 */
void ksmbd_conn_free(struct ksmbd_conn *conn)
{
        down_write(&conn_list_lock);
        hash_del(&conn->hlist);
        up_write(&conn_list_lock);

        /*
         * request_buf / preauth_info / mechToken are only ever accessed by the
         * connection handler thread that owns @conn.  ksmbd_conn_free() is
         * called from the transport free_transport() path when that thread is
         * exiting, so it is safe to release them unconditionally even when
         * ksmbd_conn_put() below is not the final putter (oplock / ksmbd_file
         * holders only retain the conn pointer, not these per-thread buffers).
         */
        xa_destroy(&conn->sessions);
        kvfree(conn->request_buf);
        kfree(conn->preauth_info);
        kfree(conn->mechToken);
        ksmbd_conn_put(conn);
}

/**
 * ksmbd_conn_alloc() - initialize a new connection instance
 *
 * Return:      ksmbd_conn struct on success, otherwise NULL
 */
struct ksmbd_conn *ksmbd_conn_alloc(void)
{
        struct ksmbd_conn *conn;

        conn = kzalloc_obj(struct ksmbd_conn, KSMBD_DEFAULT_GFP);
        if (!conn)
                return NULL;

        conn->need_neg = true;
        ksmbd_conn_set_new(conn);
        conn->local_nls = load_nls("utf8");
        if (!conn->local_nls)
                conn->local_nls = load_nls_default();
        if (IS_ENABLED(CONFIG_UNICODE))
                conn->um = utf8_load(UNICODE_AGE(12, 1, 0));
        else
                conn->um = ERR_PTR(-EOPNOTSUPP);
        if (IS_ERR(conn->um))
                conn->um = NULL;
        INIT_WORK(&conn->release_work, __ksmbd_conn_release_work);
        atomic_set(&conn->req_running, 0);
        atomic_set(&conn->r_count, 0);
        atomic_set(&conn->refcnt, 1);
        conn->total_credits = 1;
        conn->outstanding_credits = 0;

        init_waitqueue_head(&conn->req_running_q);
        init_waitqueue_head(&conn->r_count_q);
        INIT_LIST_HEAD(&conn->requests);
        INIT_LIST_HEAD(&conn->async_requests);
        spin_lock_init(&conn->request_lock);
        spin_lock_init(&conn->credits_lock);
        ida_init(&conn->async_ida);
        xa_init(&conn->sessions);

        spin_lock_init(&conn->llist_lock);
        INIT_LIST_HEAD(&conn->lock_list);

        init_rwsem(&conn->session_lock);

        return conn;
}

bool ksmbd_conn_lookup_dialect(struct ksmbd_conn *c)
{
        struct ksmbd_conn *t;
        int bkt;
        bool ret = false;

        down_read(&conn_list_lock);
        hash_for_each(conn_list, bkt, t, hlist) {
                if (memcmp(t->ClientGUID, c->ClientGUID, SMB2_CLIENT_GUID_SIZE))
                        continue;

                ret = true;
                break;
        }
        up_read(&conn_list_lock);
        return ret;
}

void ksmbd_conn_enqueue_request(struct ksmbd_work *work)
{
        struct ksmbd_conn *conn = work->conn;
        struct list_head *requests_queue = NULL;

        if (conn->ops->get_cmd_val(work) != SMB2_CANCEL_HE)
                requests_queue = &conn->requests;

        atomic_inc(&conn->req_running);
        if (requests_queue) {
                spin_lock(&conn->request_lock);
                list_add_tail(&work->request_entry, requests_queue);
                spin_unlock(&conn->request_lock);
        }
}

void ksmbd_conn_try_dequeue_request(struct ksmbd_work *work)
{
        struct ksmbd_conn *conn = work->conn;

        atomic_dec(&conn->req_running);
        if (waitqueue_active(&conn->req_running_q))
                wake_up(&conn->req_running_q);

        if (list_empty(&work->request_entry) &&
            list_empty(&work->async_request_entry))
                return;

        spin_lock(&conn->request_lock);
        list_del_init(&work->request_entry);
        spin_unlock(&conn->request_lock);
        if (work->asynchronous)
                release_async_work(work);

        wake_up_all(&conn->req_running_q);
}

void ksmbd_conn_lock(struct ksmbd_conn *conn)
{
        mutex_lock(&conn->srv_mutex);
}

void ksmbd_conn_unlock(struct ksmbd_conn *conn)
{
        mutex_unlock(&conn->srv_mutex);
}

void ksmbd_all_conn_set_status(u64 sess_id, u32 status)
{
        struct ksmbd_conn *conn;
        int bkt;

        down_read(&conn_list_lock);
        hash_for_each(conn_list, bkt, conn, hlist) {
                if (conn->binding || xa_load(&conn->sessions, sess_id))
                        WRITE_ONCE(conn->status, status);
        }
        up_read(&conn_list_lock);
}

void ksmbd_conn_wait_idle(struct ksmbd_conn *conn)
{
        wait_event(conn->req_running_q, atomic_read(&conn->req_running) < 2);
}

int ksmbd_conn_wait_idle_sess_id(struct ksmbd_conn *curr_conn, u64 sess_id)
{
        struct ksmbd_conn *conn;
        int rc, retry_count = 0, max_timeout = 120;
        int rcount, bkt;

retry_idle:
        if (retry_count >= max_timeout)
                return -EIO;

        down_read(&conn_list_lock);
        hash_for_each(conn_list, bkt, conn, hlist) {
                if (conn->binding || xa_load(&conn->sessions, sess_id)) {
                        rcount = (conn == curr_conn) ? 2 : 1;
                        if (atomic_read(&conn->req_running) >= rcount) {
                                rc = wait_event_timeout(conn->req_running_q,
                                        atomic_read(&conn->req_running) < rcount,
                                        HZ);
                                if (!rc) {
                                        up_read(&conn_list_lock);
                                        retry_count++;
                                        goto retry_idle;
                                }
                        }
                }
        }
        up_read(&conn_list_lock);

        return 0;
}

int ksmbd_conn_write(struct ksmbd_work *work)
{
        struct ksmbd_conn *conn = work->conn;
        int sent;

        if (!work->response_buf) {
                pr_err("NULL response header\n");
                return -EINVAL;
        }

        if (work->send_no_response)
                return 0;

        if (!work->iov_idx)
                return -EINVAL;

        ksmbd_conn_lock(conn);
        sent = conn->transport->ops->writev(conn->transport, work->iov,
                        work->iov_cnt,
                        get_rfc1002_len(work->iov[0].iov_base) + 4,
                        work->need_invalidate_rkey,
                        work->remote_key);
        ksmbd_conn_unlock(conn);

        if (sent < 0) {
                pr_err("Failed to send message: %d\n", sent);
                return sent;
        }

        return 0;
}

int ksmbd_conn_rdma_read(struct ksmbd_conn *conn,
                         void *buf, unsigned int buflen,
                         struct smbdirect_buffer_descriptor_v1 *desc,
                         unsigned int desc_len)
{
        int ret = -EINVAL;

        if (conn->transport->ops->rdma_read)
                ret = conn->transport->ops->rdma_read(conn->transport,
                                                      buf, buflen,
                                                      desc, desc_len);
        return ret;
}

int ksmbd_conn_rdma_write(struct ksmbd_conn *conn,
                          void *buf, unsigned int buflen,
                          struct smbdirect_buffer_descriptor_v1 *desc,
                          unsigned int desc_len)
{
        int ret = -EINVAL;

        if (conn->transport->ops->rdma_write)
                ret = conn->transport->ops->rdma_write(conn->transport,
                                                       buf, buflen,
                                                       desc, desc_len);
        return ret;
}

bool ksmbd_conn_alive(struct ksmbd_conn *conn)
{
        if (!ksmbd_server_running())
                return false;

        if (ksmbd_conn_exiting(conn))
                return false;

        if (kthread_should_stop())
                return false;

        if (atomic_read(&conn->stats.open_files_count) > 0)
                return true;

        /*
         * Stop current session if the time that get last request from client
         * is bigger than deadtime user configured and opening file count is
         * zero.
         */
        if (server_conf.deadtime > 0 &&
            time_after(jiffies, conn->last_active + server_conf.deadtime)) {
                ksmbd_debug(CONN, "No response from client in %lu minutes\n",
                            server_conf.deadtime / SMB_ECHO_INTERVAL);
                return false;
        }
        return true;
}

/* "+2" for BCC field (ByteCount, 2 bytes) */
#define SMB1_MIN_SUPPORTED_PDU_SIZE (sizeof(struct smb_hdr) + 2)
#define SMB2_MIN_SUPPORTED_PDU_SIZE (sizeof(struct smb2_pdu))
#define SMB2_TRANSFORM_MIN_SUPPORTED_PDU_SIZE   \
        (sizeof(struct smb2_transform_hdr) + sizeof(struct smb2_hdr))

/**
 * ksmbd_conn_handler_loop() - session thread to listen on new smb requests
 * @p:          connection instance
 *
 * One thread each per connection
 *
 * Return:      0 on success
 */
int ksmbd_conn_handler_loop(void *p)
{
        struct ksmbd_conn *conn = (struct ksmbd_conn *)p;
        struct ksmbd_transport *t = conn->transport;
        unsigned int pdu_size, max_allowed_pdu_size, max_req;
        __le32 proto;
        char hdr_buf[4] = {0,};
        int size;

        mutex_init(&conn->srv_mutex);
        __module_get(THIS_MODULE);

        max_req = server_conf.max_inflight_req;
        conn->last_active = jiffies;
        set_freezable();
        while (ksmbd_conn_alive(conn)) {
                if (try_to_freeze())
                        continue;

                kvfree(conn->request_buf);
                conn->request_buf = NULL;

recheck:
                if (atomic_read(&conn->req_running) + 1 > max_req) {
                        wait_event_interruptible(conn->req_running_q,
                                atomic_read(&conn->req_running) < max_req);
                        goto recheck;
                }

                size = t->ops->read(t, hdr_buf, sizeof(hdr_buf), -1);
                if (size != sizeof(hdr_buf))
                        break;

                pdu_size = get_rfc1002_len(hdr_buf);
                ksmbd_debug(CONN, "RFC1002 header %u bytes\n", pdu_size);

                if (ksmbd_conn_good(conn))
                        max_allowed_pdu_size =
                                SMB3_MAX_MSGSIZE + conn->vals->max_write_size;
                else
                        max_allowed_pdu_size = SMB3_MAX_MSGSIZE;

                if (pdu_size > max_allowed_pdu_size) {
                        pr_err_ratelimited("PDU length(%u) exceeded maximum allowed pdu size(%u) on connection(%d)\n",
                                        pdu_size, max_allowed_pdu_size,
                                        READ_ONCE(conn->status));
                        break;
                }

                /*
                 * Check maximum pdu size(0x00FFFFFF).
                 */
                if (pdu_size > MAX_STREAM_PROT_LEN)
                        break;

                if (pdu_size < SMB1_MIN_SUPPORTED_PDU_SIZE)
                        break;

                /* 4 for rfc1002 length field */
                /* 1 for implied bcc[0] */
                size = pdu_size + 4 + 1;
                conn->request_buf = kvmalloc(size, KSMBD_DEFAULT_GFP);
                if (!conn->request_buf)
                        break;

                memcpy(conn->request_buf, hdr_buf, sizeof(hdr_buf));

                /*
                 * We already read 4 bytes to find out PDU size, now
                 * read in PDU
                 */
                size = t->ops->read(t, conn->request_buf + 4, pdu_size, 2);
                if (size < 0) {
                        pr_err("sock_read failed: %d\n", size);
                        break;
                }

                if (size != pdu_size) {
                        pr_err("PDU error. Read: %d, Expected: %d\n",
                               size, pdu_size);
                        continue;
                }

                if (((struct smb2_hdr *)smb_get_msg(conn->request_buf))->ProtocolId ==
                    SMB2_COMPRESSION_TRANSFORM_ID) {
                        /*
                         * Convert the transform into a normal RFC1002-framed SMB2
                         * request before protocol validation and work allocation.
                         */
                        if (ksmbd_decompress_request(conn))
                                break;
                        pdu_size = get_rfc1002_len(conn->request_buf);
                }

                if (!ksmbd_smb_request(conn))
                        break;

                proto = *(__le32 *)smb_get_msg(conn->request_buf);
                if (proto == SMB2_PROTO_NUMBER &&
                    pdu_size < SMB2_MIN_SUPPORTED_PDU_SIZE)
                        break;

                if (proto == SMB2_TRANSFORM_PROTO_NUM &&
                    pdu_size < SMB2_TRANSFORM_MIN_SUPPORTED_PDU_SIZE)
                        break;

                if (!default_conn_ops.process_fn) {
                        pr_err("No connection request callback\n");
                        break;
                }

                if (default_conn_ops.process_fn(conn)) {
                        pr_err("Cannot handle request\n");
                        break;
                }
        }

        ksmbd_conn_set_releasing(conn);
        /* Wait till all reference dropped to the Server object*/
        ksmbd_debug(CONN, "Wait for all pending requests(%d)\n", atomic_read(&conn->r_count));
        wait_event(conn->r_count_q, atomic_read(&conn->r_count) == 0);

        if (IS_ENABLED(CONFIG_UNICODE))
                utf8_unload(conn->um);
        unload_nls(conn->local_nls);
        if (default_conn_ops.terminate_fn)
                default_conn_ops.terminate_fn(conn);
        t->ops->disconnect(t);
        module_put(THIS_MODULE);
        return 0;
}

void ksmbd_conn_init_server_callbacks(struct ksmbd_conn_ops *ops)
{
        default_conn_ops.process_fn = ops->process_fn;
        default_conn_ops.terminate_fn = ops->terminate_fn;
}

void ksmbd_conn_r_count_inc(struct ksmbd_conn *conn)
{
        atomic_inc(&conn->r_count);
}

void ksmbd_conn_r_count_dec(struct ksmbd_conn *conn)
{
        /*
         * Checking waitqueue to dropping pending requests on
         * disconnection. waitqueue_active is safe because it
         * uses atomic operation for condition.
         */
        atomic_inc(&conn->refcnt);
        if (!atomic_dec_return(&conn->r_count) && waitqueue_active(&conn->r_count_q))
                wake_up(&conn->r_count_q);

        ksmbd_conn_put(conn);
}

int ksmbd_conn_transport_init(void)
{
        int ret;

        mutex_lock(&init_lock);
        ret = ksmbd_tcp_init();
        if (ret) {
                pr_err("Failed to init TCP subsystem: %d\n", ret);
                goto out;
        }

        ret = ksmbd_rdma_init();
        if (ret) {
                pr_err("Failed to init RDMA subsystem: %d\n", ret);
                goto out;
        }
out:
        mutex_unlock(&init_lock);
        create_proc_clients();
        return ret;
}

static void stop_sessions(void)
{
        struct ksmbd_conn *conn, *target;
        struct ksmbd_transport *t;
        bool any;
        int bkt;

        /*
         * Serialised via init_lock; no concurrent stop_sessions() can
         * touch conn->stop_called, so writing it under the read lock is
         * safe.
         */
again:
        target = NULL;
        any = false;
        down_read(&conn_list_lock);
        hash_for_each(conn_list, bkt, conn, hlist) {
                any = true;
                if (conn->stop_called)
                        continue;
                atomic_inc(&conn->refcnt);
                conn->stop_called = true;
                /*
                 * Mark the connection EXITING while still holding the
                 * read lock so the selection and the status transition
                 * happen together.  Do not regress a connection that has
                 * already advanced to RELEASING on its own (e.g. the
                 * handler exited its receive loop for an unrelated
                 * reason).
                 */
                if (READ_ONCE(conn->status) != KSMBD_SESS_RELEASING)
                        ksmbd_conn_set_exiting(conn);
                target = conn;
                break;
        }
        up_read(&conn_list_lock);

        if (target) {
                t = target->transport;
                if (t->ops->shutdown)
                        t->ops->shutdown(t);
                if (atomic_dec_and_test(&target->refcnt)) {
                        ida_destroy(&target->async_ida);
                        t->ops->free_transport(t);
                        kfree(target);
                }
                goto again;
        }

        if (any) {
                msleep(100);
                goto again;
        }
}

void ksmbd_conn_transport_destroy(void)
{
        delete_proc_clients();
        mutex_lock(&init_lock);
        ksmbd_tcp_destroy();
        ksmbd_rdma_stop_listening();
        stop_sessions();
        mutex_unlock(&init_lock);
}