// SPDX-License-Identifier: GPL-2.0-or-later
/* RxRPC individual remote procedure call handling
 *
 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/slab.h>
#include <linux/module.h>
#include <linux/circ_buf.h>
#include <linux/spinlock_types.h>
#include <net/sock.h>
#include <net/af_rxrpc.h>
#include "ar-internal.h"

const char *const rxrpc_call_states[NR__RXRPC_CALL_STATES] = {
        [RXRPC_CALL_UNINITIALISED]              = "Uninit  ",
        [RXRPC_CALL_CLIENT_AWAIT_CONN]          = "ClWtConn",
        [RXRPC_CALL_CLIENT_SEND_REQUEST]        = "ClSndReq",
        [RXRPC_CALL_CLIENT_AWAIT_REPLY]         = "ClAwtRpl",
        [RXRPC_CALL_CLIENT_RECV_REPLY]          = "ClRcvRpl",
        [RXRPC_CALL_SERVER_PREALLOC]            = "SvPrealc",
        [RXRPC_CALL_SERVER_SECURING]            = "SvSecure",
        [RXRPC_CALL_SERVER_RECV_REQUEST]        = "SvRcvReq",
        [RXRPC_CALL_SERVER_ACK_REQUEST]         = "SvAckReq",
        [RXRPC_CALL_SERVER_SEND_REPLY]          = "SvSndRpl",
        [RXRPC_CALL_SERVER_AWAIT_ACK]           = "SvAwtACK",
        [RXRPC_CALL_COMPLETE]                   = "Complete",
};

const char *const rxrpc_call_completions[NR__RXRPC_CALL_COMPLETIONS] = {
        [RXRPC_CALL_SUCCEEDED]                  = "Complete",
        [RXRPC_CALL_REMOTELY_ABORTED]           = "RmtAbort",
        [RXRPC_CALL_LOCALLY_ABORTED]            = "LocAbort",
        [RXRPC_CALL_LOCAL_ERROR]                = "LocError",
        [RXRPC_CALL_NETWORK_ERROR]              = "NetError",
};

struct kmem_cache *rxrpc_call_jar;

static struct semaphore rxrpc_call_limiter =
        __SEMAPHORE_INITIALIZER(rxrpc_call_limiter, 1000);
static struct semaphore rxrpc_kernel_call_limiter =
        __SEMAPHORE_INITIALIZER(rxrpc_kernel_call_limiter, 1000);

static void rxrpc_call_timer_expired(struct timer_list *t)
{
        struct rxrpc_call *call = from_timer(call, t, timer);

        _enter("%d", call->debug_id);

        if (call->state < RXRPC_CALL_COMPLETE) {
                trace_rxrpc_timer(call, rxrpc_timer_expired, jiffies);
                rxrpc_queue_call(call);
        }
}

static struct lock_class_key rxrpc_call_user_mutex_lock_class_key;

/*
 * find an extant server call
 * - called in process context with IRQs enabled
 */
struct rxrpc_call *rxrpc_find_call_by_user_ID(struct rxrpc_sock *rx,
                                              unsigned long user_call_ID)
{
        struct rxrpc_call *call;
        struct rb_node *p;

        _enter("%p,%lx", rx, user_call_ID);

        read_lock(&rx->call_lock);

        p = rx->calls.rb_node;
        while (p) {
                call = rb_entry(p, struct rxrpc_call, sock_node);

                if (user_call_ID < call->user_call_ID)
                        p = p->rb_left;
                else if (user_call_ID > call->user_call_ID)
                        p = p->rb_right;
                else
                        goto found_extant_call;
        }

        read_unlock(&rx->call_lock);
        _leave(" = NULL");
        return NULL;

found_extant_call:
        rxrpc_get_call(call, rxrpc_call_got);
        read_unlock(&rx->call_lock);
        _leave(" = %p [%d]", call, atomic_read(&call->usage));
        return call;
}

/*
 * allocate a new call
 */
struct rxrpc_call *rxrpc_alloc_call(struct rxrpc_sock *rx, gfp_t gfp,
                                    unsigned int debug_id)
{
        struct rxrpc_call *call;
        struct rxrpc_net *rxnet = rxrpc_net(sock_net(&rx->sk));

        call = kmem_cache_zalloc(rxrpc_call_jar, gfp);
        if (!call)
                return NULL;

        call->rxtx_buffer = kcalloc(RXRPC_RXTX_BUFF_SIZE,
                                    sizeof(struct sk_buff *),
                                    gfp);
        if (!call->rxtx_buffer)
                goto nomem;

        call->rxtx_annotations = kcalloc(RXRPC_RXTX_BUFF_SIZE, sizeof(u8), gfp);
        if (!call->rxtx_annotations)
                goto nomem_2;

        mutex_init(&call->user_mutex);

        /* Prevent lockdep reporting a deadlock false positive between the afs
         * filesystem and sys_sendmsg() via the mmap sem.
         */
        if (rx->sk.sk_kern_sock)
                lockdep_set_class(&call->user_mutex,
                                  &rxrpc_call_user_mutex_lock_class_key);

        timer_setup(&call->timer, rxrpc_call_timer_expired, 0);
        INIT_WORK(&call->processor, &rxrpc_process_call);
        INIT_LIST_HEAD(&call->link);
        INIT_LIST_HEAD(&call->chan_wait_link);
        INIT_LIST_HEAD(&call->accept_link);
        INIT_LIST_HEAD(&call->recvmsg_link);
        INIT_LIST_HEAD(&call->sock_link);
        init_waitqueue_head(&call->waitq);
        spin_lock_init(&call->lock);
        spin_lock_init(&call->notify_lock);
        spin_lock_init(&call->input_lock);
        rwlock_init(&call->state_lock);
        atomic_set(&call->usage, 1);
        call->debug_id = debug_id;
        call->tx_total_len = -1;
        call->next_rx_timo = 20 * HZ;
        call->next_req_timo = 1 * HZ;

        memset(&call->sock_node, 0xed, sizeof(call->sock_node));

        /* Leave space in the ring to handle a maxed-out jumbo packet */
        call->rx_winsize = rxrpc_rx_window_size;
        call->tx_winsize = 16;
        call->rx_expect_next = 1;

        call->cong_cwnd = 2;
        call->cong_ssthresh = RXRPC_RXTX_BUFF_SIZE - 1;

        call->rxnet = rxnet;
        call->rtt_avail = RXRPC_CALL_RTT_AVAIL_MASK;
        atomic_inc(&rxnet->nr_calls);
        return call;

nomem_2:
        kfree(call->rxtx_buffer);
nomem:
        kmem_cache_free(rxrpc_call_jar, call);
        return NULL;
}

/*
 * Allocate a new client call.
 */
static struct rxrpc_call *rxrpc_alloc_client_call(struct rxrpc_sock *rx,
                                                  struct sockaddr_rxrpc *srx,
                                                  gfp_t gfp,
                                                  unsigned int debug_id)
{
        struct rxrpc_call *call;
        ktime_t now;

        _enter("");

        call = rxrpc_alloc_call(rx, gfp, debug_id);
        if (!call)
                return ERR_PTR(-ENOMEM);
        call->state = RXRPC_CALL_CLIENT_AWAIT_CONN;
        call->service_id = srx->srx_service;
        call->tx_phase = true;
        now = ktime_get_real();
        call->acks_latest_ts = now;
        call->cong_tstamp = now;

        _leave(" = %p", call);
        return call;
}

/*
 * Initiate the call ack/resend/expiry timer.
 */
static void rxrpc_start_call_timer(struct rxrpc_call *call)
{
        unsigned long now = jiffies;
        unsigned long j = now + MAX_JIFFY_OFFSET;

        call->ack_at = j;
        call->ack_lost_at = j;
        call->resend_at = j;
        call->ping_at = j;
        call->expect_rx_by = j;
        call->expect_req_by = j;
        call->expect_term_by = j;
        call->timer.expires = now;
}

/*
 * Wait for a call slot to become available.
 */
static struct semaphore *rxrpc_get_call_slot(struct rxrpc_call_params *p, gfp_t gfp)
{
        struct semaphore *limiter = &rxrpc_call_limiter;

        if (p->kernel)
                limiter = &rxrpc_kernel_call_limiter;
        if (p->interruptibility == RXRPC_UNINTERRUPTIBLE) {
                down(limiter);
                return limiter;
        }
        return down_interruptible(limiter) < 0 ? NULL : limiter;
}

/*
 * Release a call slot.
 */
static void rxrpc_put_call_slot(struct rxrpc_call *call)
{
        struct semaphore *limiter = &rxrpc_call_limiter;

        if (test_bit(RXRPC_CALL_KERNEL, &call->flags))
                limiter = &rxrpc_kernel_call_limiter;
        up(limiter);
}

/*
 * Set up a call for the given parameters.
 * - Called with the socket lock held, which it must release.
 * - If it returns a call, the call's lock will need releasing by the caller.
 */
struct rxrpc_call *rxrpc_new_client_call(struct rxrpc_sock *rx,
                                         struct rxrpc_conn_parameters *cp,
                                         struct sockaddr_rxrpc *srx,
                                         struct rxrpc_call_params *p,
                                         gfp_t gfp,
                                         unsigned int debug_id)
        __releases(&rx->sk.sk_lock.slock)
        __acquires(&call->user_mutex)
{
        struct rxrpc_call *call, *xcall;
        struct rxrpc_net *rxnet;
        struct semaphore *limiter;
        struct rb_node *parent, **pp;
        const void *here = __builtin_return_address(0);
        int ret;

        _enter("%p,%lx", rx, p->user_call_ID);

        limiter = rxrpc_get_call_slot(p, gfp);
        if (!limiter)
                return ERR_PTR(-ERESTARTSYS);

        call = rxrpc_alloc_client_call(rx, srx, gfp, debug_id);
        if (IS_ERR(call)) {
                release_sock(&rx->sk);
                up(limiter);
                _leave(" = %ld", PTR_ERR(call));
                return call;
        }

        call->interruptibility = p->interruptibility;
        call->tx_total_len = p->tx_total_len;
        trace_rxrpc_call(call->debug_id, rxrpc_call_new_client,
                         atomic_read(&call->usage),
                         here, (const void *)p->user_call_ID);
        if (p->kernel)
                __set_bit(RXRPC_CALL_KERNEL, &call->flags);

        /* We need to protect a partially set up call against the user as we
         * will be acting outside the socket lock.
         */
        mutex_lock(&call->user_mutex);

        /* Publish the call, even though it is incompletely set up as yet */
        write_lock(&rx->call_lock);

        pp = &rx->calls.rb_node;
        parent = NULL;
        while (*pp) {
                parent = *pp;
                xcall = rb_entry(parent, struct rxrpc_call, sock_node);

                if (p->user_call_ID < xcall->user_call_ID)
                        pp = &(*pp)->rb_left;
                else if (p->user_call_ID > xcall->user_call_ID)
                        pp = &(*pp)->rb_right;
                else
                        goto error_dup_user_ID;
        }

        rcu_assign_pointer(call->socket, rx);
        call->user_call_ID = p->user_call_ID;
        __set_bit(RXRPC_CALL_HAS_USERID, &call->flags);
        rxrpc_get_call(call, rxrpc_call_got_userid);
        rb_link_node(&call->sock_node, parent, pp);
        rb_insert_color(&call->sock_node, &rx->calls);
        list_add(&call->sock_link, &rx->sock_calls);

        write_unlock(&rx->call_lock);

        rxnet = call->rxnet;
        write_lock(&rxnet->call_lock);
        list_add_tail(&call->link, &rxnet->calls);
        write_unlock(&rxnet->call_lock);

        /* From this point on, the call is protected by its own lock. */
        release_sock(&rx->sk);

        /* Set up or get a connection record and set the protocol parameters,
         * including channel number and call ID.
         */
        ret = rxrpc_connect_call(rx, call, cp, srx, gfp);
        if (ret < 0)
                goto error_attached_to_socket;

        trace_rxrpc_call(call->debug_id, rxrpc_call_connected,
                         atomic_read(&call->usage), here, NULL);

        rxrpc_start_call_timer(call);

        _net("CALL new %d on CONN %d", call->debug_id, call->conn->debug_id);

        _leave(" = %p [new]", call);
        return call;

        /* We unexpectedly found the user ID in the list after taking
         * the call_lock.  This shouldn't happen unless the user races
         * with itself and tries to add the same user ID twice at the
         * same time in different threads.
         */
error_dup_user_ID:
        write_unlock(&rx->call_lock);
        release_sock(&rx->sk);
        __rxrpc_set_call_completion(call, RXRPC_CALL_LOCAL_ERROR,
                                    RX_CALL_DEAD, -EEXIST);
        trace_rxrpc_call(call->debug_id, rxrpc_call_error,
                         atomic_read(&call->usage), here, ERR_PTR(-EEXIST));
        rxrpc_release_call(rx, call);
        mutex_unlock(&call->user_mutex);
        rxrpc_put_call(call, rxrpc_call_put);
        _leave(" = -EEXIST");
        return ERR_PTR(-EEXIST);

        /* We got an error, but the call is attached to the socket and is in
         * need of release.  However, we might now race with recvmsg() when
         * completing the call queues it.  Return 0 from sys_sendmsg() and
         * leave the error to recvmsg() to deal with.
         */
error_attached_to_socket:
        trace_rxrpc_call(call->debug_id, rxrpc_call_error,
                         atomic_read(&call->usage), here, ERR_PTR(ret));
        set_bit(RXRPC_CALL_DISCONNECTED, &call->flags);
        __rxrpc_set_call_completion(call, RXRPC_CALL_LOCAL_ERROR,
                                    RX_CALL_DEAD, ret);
        _leave(" = c=%08x [err]", call->debug_id);
        return call;
}

/*
 * Set up an incoming call.  call->conn points to the connection.
 * This is called in BH context and isn't allowed to fail.
 */
void rxrpc_incoming_call(struct rxrpc_sock *rx,
                         struct rxrpc_call *call,
                         struct sk_buff *skb)
{
        struct rxrpc_connection *conn = call->conn;
        struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
        u32 chan;

        _enter(",%d", call->conn->debug_id);

        rcu_assign_pointer(call->socket, rx);
        call->call_id           = sp->hdr.callNumber;
        call->service_id        = sp->hdr.serviceId;
        call->cid               = sp->hdr.cid;
        call->state             = RXRPC_CALL_SERVER_SECURING;
        call->cong_tstamp       = skb->tstamp;

        /* Set the channel for this call.  We don't get channel_lock as we're
         * only defending against the data_ready handler (which we're called
         * from) and the RESPONSE packet parser (which is only really
         * interested in call_counter and can cope with a disagreement with the
         * call pointer).
         */
        chan = sp->hdr.cid & RXRPC_CHANNELMASK;
        conn->channels[chan].call_counter = call->call_id;
        conn->channels[chan].call_id = call->call_id;
        rcu_assign_pointer(conn->channels[chan].call, call);

        spin_lock(&conn->params.peer->lock);
        hlist_add_head_rcu(&call->error_link, &conn->params.peer->error_targets);
        spin_unlock(&conn->params.peer->lock);

        _net("CALL incoming %d on CONN %d", call->debug_id, call->conn->debug_id);

        rxrpc_start_call_timer(call);
        _leave("");
}

/*
 * Queue a call's work processor, getting a ref to pass to the work queue.
 */
bool rxrpc_queue_call(struct rxrpc_call *call)
{
        const void *here = __builtin_return_address(0);
        int n = atomic_fetch_add_unless(&call->usage, 1, 0);
        if (n == 0)
                return false;
        if (rxrpc_queue_work(&call->processor))
                trace_rxrpc_call(call->debug_id, rxrpc_call_queued, n + 1,
                                 here, NULL);
        else
                rxrpc_put_call(call, rxrpc_call_put_noqueue);
        return true;
}

/*
 * Queue a call's work processor, passing the callers ref to the work queue.
 */
bool __rxrpc_queue_call(struct rxrpc_call *call)
{
        const void *here = __builtin_return_address(0);
        int n = atomic_read(&call->usage);
        ASSERTCMP(n, >=, 1);
        if (rxrpc_queue_work(&call->processor))
                trace_rxrpc_call(call->debug_id, rxrpc_call_queued_ref, n,
                                 here, NULL);
        else
                rxrpc_put_call(call, rxrpc_call_put_noqueue);
        return true;
}

/*
 * Note the re-emergence of a call.
 */
void rxrpc_see_call(struct rxrpc_call *call)
{
        const void *here = __builtin_return_address(0);
        if (call) {
                int n = atomic_read(&call->usage);

                trace_rxrpc_call(call->debug_id, rxrpc_call_seen, n,
                                 here, NULL);
        }
}

/*
 * Note the addition of a ref on a call.
 */
void rxrpc_get_call(struct rxrpc_call *call, enum rxrpc_call_trace op)
{
        const void *here = __builtin_return_address(0);
        int n = atomic_inc_return(&call->usage);

        trace_rxrpc_call(call->debug_id, op, n, here, NULL);
}

/*
 * Clean up the RxTx skb ring.
 */
static void rxrpc_cleanup_ring(struct rxrpc_call *call)
{
        int i;

        for (i = 0; i < RXRPC_RXTX_BUFF_SIZE; i++) {
                rxrpc_free_skb(call->rxtx_buffer[i], rxrpc_skb_cleaned);
                call->rxtx_buffer[i] = NULL;
        }
}

/*
 * Detach a call from its owning socket.
 */
void rxrpc_release_call(struct rxrpc_sock *rx, struct rxrpc_call *call)
{
        const void *here = __builtin_return_address(0);
        struct rxrpc_connection *conn = call->conn;
        bool put = false;

        _enter("{%d,%d}", call->debug_id, atomic_read(&call->usage));

        trace_rxrpc_call(call->debug_id, rxrpc_call_release,
                         atomic_read(&call->usage),
                         here, (const void *)call->flags);

        ASSERTCMP(call->state, ==, RXRPC_CALL_COMPLETE);

        spin_lock_bh(&call->lock);
        if (test_and_set_bit(RXRPC_CALL_RELEASED, &call->flags))
                BUG();
        spin_unlock_bh(&call->lock);

        rxrpc_put_call_slot(call);

        del_timer_sync(&call->timer);

        /* Make sure we don't get any more notifications */
        write_lock_bh(&rx->recvmsg_lock);

        if (!list_empty(&call->recvmsg_link)) {
                _debug("unlinking once-pending call %p { e=%lx f=%lx }",
                       call, call->events, call->flags);
                list_del(&call->recvmsg_link);
                put = true;
        }

        /* list_empty() must return false in rxrpc_notify_socket() */
        call->recvmsg_link.next = NULL;
        call->recvmsg_link.prev = NULL;

        write_unlock_bh(&rx->recvmsg_lock);
        if (put)
                rxrpc_put_call(call, rxrpc_call_put);

        write_lock(&rx->call_lock);

        if (test_and_clear_bit(RXRPC_CALL_HAS_USERID, &call->flags)) {
                rb_erase(&call->sock_node, &rx->calls);
                memset(&call->sock_node, 0xdd, sizeof(call->sock_node));
                rxrpc_put_call(call, rxrpc_call_put_userid);
        }

        list_del(&call->sock_link);
        write_unlock(&rx->call_lock);

        _debug("RELEASE CALL %p (%d CONN %p)", call, call->debug_id, conn);

        if (conn && !test_bit(RXRPC_CALL_DISCONNECTED, &call->flags))
                rxrpc_disconnect_call(call);
        if (call->security)
                call->security->free_call_crypto(call);
        _leave("");
}

/*
 * release all the calls associated with a socket
 */
void rxrpc_release_calls_on_socket(struct rxrpc_sock *rx)
{
        struct rxrpc_call *call;

        _enter("%p", rx);

        while (!list_empty(&rx->to_be_accepted)) {
                call = list_entry(rx->to_be_accepted.next,
                                  struct rxrpc_call, accept_link);
                list_del(&call->accept_link);
                rxrpc_abort_call("SKR", call, 0, RX_CALL_DEAD, -ECONNRESET);
                rxrpc_put_call(call, rxrpc_call_put);
        }

        while (!list_empty(&rx->sock_calls)) {
                call = list_entry(rx->sock_calls.next,
                                  struct rxrpc_call, sock_link);
                rxrpc_get_call(call, rxrpc_call_got);
                rxrpc_abort_call("SKT", call, 0, RX_CALL_DEAD, -ECONNRESET);
                rxrpc_send_abort_packet(call);
                rxrpc_release_call(rx, call);
                rxrpc_put_call(call, rxrpc_call_put);
        }

        _leave("");
}

/*
 * release a call
 */
void rxrpc_put_call(struct rxrpc_call *call, enum rxrpc_call_trace op)
{
        struct rxrpc_net *rxnet = call->rxnet;
        const void *here = __builtin_return_address(0);
        unsigned int debug_id = call->debug_id;
        int n;

        ASSERT(call != NULL);

        n = atomic_dec_return(&call->usage);
        trace_rxrpc_call(debug_id, op, n, here, NULL);
        ASSERTCMP(n, >=, 0);
        if (n == 0) {
                _debug("call %d dead", call->debug_id);
                ASSERTCMP(call->state, ==, RXRPC_CALL_COMPLETE);

                if (!list_empty(&call->link)) {
                        write_lock(&rxnet->call_lock);
                        list_del_init(&call->link);
                        write_unlock(&rxnet->call_lock);
                }

                rxrpc_cleanup_call(call);
        }
}

/*
 * Final call destruction - but must be done in process context.
 */
static void rxrpc_destroy_call(struct work_struct *work)
{
        struct rxrpc_call *call = container_of(work, struct rxrpc_call, processor);
        struct rxrpc_net *rxnet = call->rxnet;

        rxrpc_put_connection(call->conn);
        rxrpc_put_peer(call->peer);
        kfree(call->rxtx_buffer);
        kfree(call->rxtx_annotations);
        kmem_cache_free(rxrpc_call_jar, call);
        if (atomic_dec_and_test(&rxnet->nr_calls))
                wake_up_var(&rxnet->nr_calls);
}

/*
 * Final call destruction under RCU.
 */
static void rxrpc_rcu_destroy_call(struct rcu_head *rcu)
{
        struct rxrpc_call *call = container_of(rcu, struct rxrpc_call, rcu);

        if (in_softirq()) {
                INIT_WORK(&call->processor, rxrpc_destroy_call);
                if (!rxrpc_queue_work(&call->processor))
                        BUG();
        } else {
                rxrpc_destroy_call(&call->processor);
        }
}

/*
 * clean up a call
 */
void rxrpc_cleanup_call(struct rxrpc_call *call)
{
        _net("DESTROY CALL %d", call->debug_id);

        memset(&call->sock_node, 0xcd, sizeof(call->sock_node));

        del_timer_sync(&call->timer);

        ASSERTCMP(call->state, ==, RXRPC_CALL_COMPLETE);
        ASSERT(test_bit(RXRPC_CALL_RELEASED, &call->flags));

        rxrpc_cleanup_ring(call);
        rxrpc_free_skb(call->tx_pending, rxrpc_skb_cleaned);

        call_rcu(&call->rcu, rxrpc_rcu_destroy_call);
}

/*
 * Make sure that all calls are gone from a network namespace.  To reach this
 * point, any open UDP sockets in that namespace must have been closed, so any
 * outstanding calls cannot be doing I/O.
 */
void rxrpc_destroy_all_calls(struct rxrpc_net *rxnet)
{
        struct rxrpc_call *call;

        _enter("");

        if (!list_empty(&rxnet->calls)) {
                write_lock(&rxnet->call_lock);

                while (!list_empty(&rxnet->calls)) {
                        call = list_entry(rxnet->calls.next,
                                          struct rxrpc_call, link);
                        _debug("Zapping call %p", call);

                        rxrpc_see_call(call);
                        list_del_init(&call->link);

                        pr_err("Call %p still in use (%d,%s,%lx,%lx)!\n",
                               call, atomic_read(&call->usage),
                               rxrpc_call_states[call->state],
                               call->flags, call->events);

                        write_unlock(&rxnet->call_lock);
                        cond_resched();
                        write_lock(&rxnet->call_lock);
                }

                write_unlock(&rxnet->call_lock);
        }

        atomic_dec(&rxnet->nr_calls);
        wait_var_event(&rxnet->nr_calls, !atomic_read(&rxnet->nr_calls));
}