// 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 "transport_tcp.h"
#include "transport_rdma.h"

static DEFINE_MUTEX(init_lock);

static struct ksmbd_conn_ops default_conn_ops;

LIST_HEAD(conn_list);
DEFINE_RWLOCK(conn_list_lock);

/**
 * ksmbd_conn_free() - free resources of the connection instance
 *
 * @conn:       connection instance to be cleand 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)
{
        write_lock(&conn_list_lock);
        list_del(&conn->conns_list);
        write_unlock(&conn_list_lock);

        kvfree(conn->request_buf);
        kfree(conn->preauth_info);
        kfree(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(sizeof(struct ksmbd_conn), GFP_KERNEL);
        if (!conn)
                return NULL;

        conn->need_neg = true;
        conn->status = KSMBD_SESS_NEW;
        conn->local_nls = load_nls("utf8");
        if (!conn->local_nls)
                conn->local_nls = load_nls_default();
        atomic_set(&conn->req_running, 0);
        atomic_set(&conn->r_count, 0);
        conn->total_credits = 1;
        conn->outstanding_credits = 1;

        init_waitqueue_head(&conn->req_running_q);
        INIT_LIST_HEAD(&conn->conns_list);
        INIT_LIST_HEAD(&conn->sessions);
        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);

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

        write_lock(&conn_list_lock);
        list_add(&conn->conns_list, &conn_list);
        write_unlock(&conn_list_lock);
        return conn;
}

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

        read_lock(&conn_list_lock);
        list_for_each_entry(t, &conn_list, conns_list) {
                if (memcmp(t->ClientGUID, c->ClientGUID, SMB2_CLIENT_GUID_SIZE))
                        continue;

                ret = true;
                break;
        }
        read_unlock(&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;
                work->syncronous = true;
        }

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

int ksmbd_conn_try_dequeue_request(struct ksmbd_work *work)
{
        struct ksmbd_conn *conn = work->conn;
        int ret = 1;

        if (list_empty(&work->request_entry) &&
            list_empty(&work->async_request_entry))
                return 0;

        if (!work->multiRsp)
                atomic_dec(&conn->req_running);
        spin_lock(&conn->request_lock);
        if (!work->multiRsp) {
                list_del_init(&work->request_entry);
                if (work->syncronous == false)
                        list_del_init(&work->async_request_entry);
                ret = 0;
        }
        spin_unlock(&conn->request_lock);

        wake_up_all(&conn->req_running_q);
        return ret;
}

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

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

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

int ksmbd_conn_write(struct ksmbd_work *work)
{
        struct ksmbd_conn *conn = work->conn;
        size_t len = 0;
        int sent;
        struct kvec iov[3];
        int iov_idx = 0;

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

        if (work->tr_buf) {
                iov[iov_idx] = (struct kvec) { work->tr_buf,
                                sizeof(struct smb2_transform_hdr) + 4 };
                len += iov[iov_idx++].iov_len;
        }

        if (work->aux_payload_sz) {
                iov[iov_idx] = (struct kvec) { work->response_buf, work->resp_hdr_sz };
                len += iov[iov_idx++].iov_len;
                iov[iov_idx] = (struct kvec) { work->aux_payload_buf, work->aux_payload_sz };
                len += iov[iov_idx++].iov_len;
        } else {
                if (work->tr_buf)
                        iov[iov_idx].iov_len = work->resp_hdr_sz;
                else
                        iov[iov_idx].iov_len = get_rfc1002_len(work->response_buf) + 4;
                iov[iov_idx].iov_base = work->response_buf;
                len += iov[iov_idx++].iov_len;
        }

        ksmbd_conn_lock(conn);
        sent = conn->transport->ops->writev(conn->transport, &iov[0],
                                        iov_idx, len,
                                        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, u32 remote_key, u64 remote_offset,
                         u32 remote_len)
{
        int ret = -EINVAL;

        if (conn->transport->ops->rdma_read)
                ret = conn->transport->ops->rdma_read(conn->transport,
                                                      buf, buflen,
                                                      remote_key, remote_offset,
                                                      remote_len);
        return ret;
}

int ksmbd_conn_rdma_write(struct ksmbd_conn *conn, void *buf,
                          unsigned int buflen, u32 remote_key,
                          u64 remote_offset, u32 remote_len)
{
        int ret = -EINVAL;

        if (conn->transport->ops->rdma_write)
                ret = conn->transport->ops->rdma_write(conn->transport,
                                                       buf, buflen,
                                                       remote_key, remote_offset,
                                                       remote_len);
        return ret;
}

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

        if (conn->status == KSMBD_SESS_EXITING)
                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;
}

/**
 * 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;
        char hdr_buf[4] = {0,};
        int size;

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

        if (t->ops->prepare && t->ops->prepare(t))
                goto out;

        conn->last_active = jiffies;
        while (ksmbd_conn_alive(conn)) {
                if (try_to_freeze())
                        continue;

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

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

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

                /*
                 * Check if pdu size is valid (min : smb header size,
                 * max : 0x00FFFFFF).
                 */
                if (pdu_size < __SMB2_HEADER_STRUCTURE_SIZE ||
                    pdu_size > MAX_STREAM_PROT_LEN) {
                        continue;
                }

                /* 4 for rfc1002 length field */
                size = pdu_size + 4;
                conn->request_buf = kvmalloc(size, GFP_KERNEL);
                if (!conn->request_buf)
                        continue;

                memcpy(conn->request_buf, hdr_buf, sizeof(hdr_buf));
                if (!ksmbd_smb_request(conn))
                        break;

                /*
                 * 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);
                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 (!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;
                }
        }

out:
        /* Wait till all reference dropped to the Server object*/
        while (atomic_read(&conn->r_count) > 0)
                schedule_timeout(HZ);

        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;
}

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);
        return ret;
}

static void stop_sessions(void)
{
        struct ksmbd_conn *conn;
        struct ksmbd_transport *t;

again:
        read_lock(&conn_list_lock);
        list_for_each_entry(conn, &conn_list, conns_list) {
                struct task_struct *task;

                t = conn->transport;
                task = t->handler;
                if (task)
                        ksmbd_debug(CONN, "Stop session handler %s/%d\n",
                                    task->comm, task_pid_nr(task));
                conn->status = KSMBD_SESS_EXITING;
                if (t->ops->shutdown) {
                        read_unlock(&conn_list_lock);
                        t->ops->shutdown(t);
                        read_lock(&conn_list_lock);
                }
        }
        read_unlock(&conn_list_lock);

        if (!list_empty(&conn_list)) {
                schedule_timeout_interruptible(HZ / 10); /* 100ms */
                goto again;
        }
}

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