// SPDX-License-Identifier: GPL-2.0-or-later
/* RxRPC recvmsg() implementation
 *
 * 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/net.h>
#include <linux/skbuff.h>
#include <linux/export.h>
#include <linux/sched/signal.h>

#include <net/sock.h>
#include <net/af_rxrpc.h>
#include "ar-internal.h"

/*
 * Post a call for attention by the socket or kernel service.  Further
 * notifications are suppressed by putting recvmsg_link on a dummy queue.
 */
void rxrpc_notify_socket(struct rxrpc_call *call)
{
        struct rxrpc_sock *rx;
        struct sock *sk;

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

        if (!list_empty(&call->recvmsg_link))
                return;

        rcu_read_lock();

        rx = rcu_dereference(call->socket);
        sk = &rx->sk;
        if (rx && sk->sk_state < RXRPC_CLOSE) {
                if (call->notify_rx) {
                        spin_lock_bh(&call->notify_lock);
                        call->notify_rx(sk, call, call->user_call_ID);
                        spin_unlock_bh(&call->notify_lock);
                } else {
                        write_lock_bh(&rx->recvmsg_lock);
                        if (list_empty(&call->recvmsg_link)) {
                                rxrpc_get_call(call, rxrpc_call_got);
                                list_add_tail(&call->recvmsg_link, &rx->recvmsg_q);
                        }
                        write_unlock_bh(&rx->recvmsg_lock);

                        if (!sock_flag(sk, SOCK_DEAD)) {
                                _debug("call %ps", sk->sk_data_ready);
                                sk->sk_data_ready(sk);
                        }
                }
        }

        rcu_read_unlock();
        _leave("");
}

/*
 * Transition a call to the complete state.
 */
bool __rxrpc_set_call_completion(struct rxrpc_call *call,
                                 enum rxrpc_call_completion compl,
                                 u32 abort_code,
                                 int error)
{
        if (call->state < RXRPC_CALL_COMPLETE) {
                call->abort_code = abort_code;
                call->error = error;
                call->completion = compl;
                call->state = RXRPC_CALL_COMPLETE;
                trace_rxrpc_call_complete(call);
                wake_up(&call->waitq);
                rxrpc_notify_socket(call);
                return true;
        }
        return false;
}

bool rxrpc_set_call_completion(struct rxrpc_call *call,
                               enum rxrpc_call_completion compl,
                               u32 abort_code,
                               int error)
{
        bool ret = false;

        if (call->state < RXRPC_CALL_COMPLETE) {
                write_lock_bh(&call->state_lock);
                ret = __rxrpc_set_call_completion(call, compl, abort_code, error);
                write_unlock_bh(&call->state_lock);
        }
        return ret;
}

/*
 * Record that a call successfully completed.
 */
bool __rxrpc_call_completed(struct rxrpc_call *call)
{
        return __rxrpc_set_call_completion(call, RXRPC_CALL_SUCCEEDED, 0, 0);
}

bool rxrpc_call_completed(struct rxrpc_call *call)
{
        bool ret = false;

        if (call->state < RXRPC_CALL_COMPLETE) {
                write_lock_bh(&call->state_lock);
                ret = __rxrpc_call_completed(call);
                write_unlock_bh(&call->state_lock);
        }
        return ret;
}

/*
 * Record that a call is locally aborted.
 */
bool __rxrpc_abort_call(const char *why, struct rxrpc_call *call,
                        rxrpc_seq_t seq, u32 abort_code, int error)
{
        trace_rxrpc_abort(call->debug_id, why, call->cid, call->call_id, seq,
                          abort_code, error);
        return __rxrpc_set_call_completion(call, RXRPC_CALL_LOCALLY_ABORTED,
                                           abort_code, error);
}

bool rxrpc_abort_call(const char *why, struct rxrpc_call *call,
                      rxrpc_seq_t seq, u32 abort_code, int error)
{
        bool ret;

        write_lock_bh(&call->state_lock);
        ret = __rxrpc_abort_call(why, call, seq, abort_code, error);
        write_unlock_bh(&call->state_lock);
        return ret;
}

/*
 * Pass a call terminating message to userspace.
 */
static int rxrpc_recvmsg_term(struct rxrpc_call *call, struct msghdr *msg)
{
        u32 tmp = 0;
        int ret;

        switch (call->completion) {
        case RXRPC_CALL_SUCCEEDED:
                ret = 0;
                if (rxrpc_is_service_call(call))
                        ret = put_cmsg(msg, SOL_RXRPC, RXRPC_ACK, 0, &tmp);
                break;
        case RXRPC_CALL_REMOTELY_ABORTED:
                tmp = call->abort_code;
                ret = put_cmsg(msg, SOL_RXRPC, RXRPC_ABORT, 4, &tmp);
                break;
        case RXRPC_CALL_LOCALLY_ABORTED:
                tmp = call->abort_code;
                ret = put_cmsg(msg, SOL_RXRPC, RXRPC_ABORT, 4, &tmp);
                break;
        case RXRPC_CALL_NETWORK_ERROR:
                tmp = -call->error;
                ret = put_cmsg(msg, SOL_RXRPC, RXRPC_NET_ERROR, 4, &tmp);
                break;
        case RXRPC_CALL_LOCAL_ERROR:
                tmp = -call->error;
                ret = put_cmsg(msg, SOL_RXRPC, RXRPC_LOCAL_ERROR, 4, &tmp);
                break;
        default:
                pr_err("Invalid terminal call state %u\n", call->state);
                BUG();
                break;
        }

        trace_rxrpc_recvmsg(call, rxrpc_recvmsg_terminal, call->rx_hard_ack,
                            call->rx_pkt_offset, call->rx_pkt_len, ret);
        return ret;
}

/*
 * End the packet reception phase.
 */
static void rxrpc_end_rx_phase(struct rxrpc_call *call, rxrpc_serial_t serial)
{
        _enter("%d,%s", call->debug_id, rxrpc_call_states[call->state]);

        trace_rxrpc_receive(call, rxrpc_receive_end, 0, call->rx_top);
        ASSERTCMP(call->rx_hard_ack, ==, call->rx_top);

        if (call->state == RXRPC_CALL_CLIENT_RECV_REPLY) {
                rxrpc_propose_ACK(call, RXRPC_ACK_IDLE, serial, false, true,
                                  rxrpc_propose_ack_terminal_ack);
                //rxrpc_send_ack_packet(call, false, NULL);
        }

        write_lock_bh(&call->state_lock);

        switch (call->state) {
        case RXRPC_CALL_CLIENT_RECV_REPLY:
                __rxrpc_call_completed(call);
                write_unlock_bh(&call->state_lock);
                break;

        case RXRPC_CALL_SERVER_RECV_REQUEST:
                call->tx_phase = true;
                call->state = RXRPC_CALL_SERVER_ACK_REQUEST;
                call->expect_req_by = jiffies + MAX_JIFFY_OFFSET;
                write_unlock_bh(&call->state_lock);
                rxrpc_propose_ACK(call, RXRPC_ACK_DELAY, serial, false, true,
                                  rxrpc_propose_ack_processing_op);
                break;
        default:
                write_unlock_bh(&call->state_lock);
                break;
        }
}

/*
 * Discard a packet we've used up and advance the Rx window by one.
 */
static void rxrpc_rotate_rx_window(struct rxrpc_call *call)
{
        struct rxrpc_skb_priv *sp;
        struct sk_buff *skb;
        rxrpc_serial_t serial;
        rxrpc_seq_t hard_ack, top;
        bool last = false;
        u8 subpacket;
        int ix;

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

        hard_ack = call->rx_hard_ack;
        top = smp_load_acquire(&call->rx_top);
        ASSERT(before(hard_ack, top));

        hard_ack++;
        ix = hard_ack & RXRPC_RXTX_BUFF_MASK;
        skb = call->rxtx_buffer[ix];
        rxrpc_see_skb(skb, rxrpc_skb_rotated);
        sp = rxrpc_skb(skb);

        subpacket = call->rxtx_annotations[ix] & RXRPC_RX_ANNO_SUBPACKET;
        serial = sp->hdr.serial + subpacket;

        if (subpacket == sp->nr_subpackets - 1 &&
            sp->rx_flags & RXRPC_SKB_INCL_LAST)
                last = true;

        call->rxtx_buffer[ix] = NULL;
        call->rxtx_annotations[ix] = 0;
        /* Barrier against rxrpc_input_data(). */
        smp_store_release(&call->rx_hard_ack, hard_ack);

        rxrpc_free_skb(skb, rxrpc_skb_freed);

        trace_rxrpc_receive(call, rxrpc_receive_rotate, serial, hard_ack);
        if (last) {
                rxrpc_end_rx_phase(call, serial);
        } else {
                /* Check to see if there's an ACK that needs sending. */
                if (after_eq(hard_ack, call->ackr_consumed + 2) ||
                    after_eq(top, call->ackr_seen + 2) ||
                    (hard_ack == top && after(hard_ack, call->ackr_consumed)))
                        rxrpc_propose_ACK(call, RXRPC_ACK_DELAY, serial,
                                          true, true,
                                          rxrpc_propose_ack_rotate_rx);
                if (call->ackr_reason && call->ackr_reason != RXRPC_ACK_DELAY)
                        rxrpc_send_ack_packet(call, false, NULL);
        }
}

/*
 * Decrypt and verify a (sub)packet.  The packet's length may be changed due to
 * padding, but if this is the case, the packet length will be resident in the
 * socket buffer.  Note that we can't modify the master skb info as the skb may
 * be the home to multiple subpackets.
 */
static int rxrpc_verify_packet(struct rxrpc_call *call, struct sk_buff *skb,
                               u8 annotation,
                               unsigned int offset, unsigned int len)
{
        struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
        rxrpc_seq_t seq = sp->hdr.seq;
        u16 cksum = sp->hdr.cksum;
        u8 subpacket = annotation & RXRPC_RX_ANNO_SUBPACKET;

        _enter("");

        /* For all but the head jumbo subpacket, the security checksum is in a
         * jumbo header immediately prior to the data.
         */
        if (subpacket > 0) {
                __be16 tmp;
                if (skb_copy_bits(skb, offset - 2, &tmp, 2) < 0)
                        BUG();
                cksum = ntohs(tmp);
                seq += subpacket;
        }

        return call->security->verify_packet(call, skb, offset, len,
                                             seq, cksum);
}

/*
 * Locate the data within a packet.  This is complicated by:
 *
 * (1) An skb may contain a jumbo packet - so we have to find the appropriate
 *     subpacket.
 *
 * (2) The (sub)packets may be encrypted and, if so, the encrypted portion
 *     contains an extra header which includes the true length of the data,
 *     excluding any encrypted padding.
 */
static int rxrpc_locate_data(struct rxrpc_call *call, struct sk_buff *skb,
                             u8 *_annotation,
                             unsigned int *_offset, unsigned int *_len,
                             bool *_last)
{
        struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
        unsigned int offset = sizeof(struct rxrpc_wire_header);
        unsigned int len;
        bool last = false;
        int ret;
        u8 annotation = *_annotation;
        u8 subpacket = annotation & RXRPC_RX_ANNO_SUBPACKET;

        /* Locate the subpacket */
        offset += subpacket * RXRPC_JUMBO_SUBPKTLEN;
        len = skb->len - offset;
        if (subpacket < sp->nr_subpackets - 1)
                len = RXRPC_JUMBO_DATALEN;
        else if (sp->rx_flags & RXRPC_SKB_INCL_LAST)
                last = true;

        if (!(annotation & RXRPC_RX_ANNO_VERIFIED)) {
                ret = rxrpc_verify_packet(call, skb, annotation, offset, len);
                if (ret < 0)
                        return ret;
                *_annotation |= RXRPC_RX_ANNO_VERIFIED;
        }

        *_offset = offset;
        *_len = len;
        *_last = last;
        call->security->locate_data(call, skb, _offset, _len);
        return 0;
}

/*
 * Deliver messages to a call.  This keeps processing packets until the buffer
 * is filled and we find either more DATA (returns 0) or the end of the DATA
 * (returns 1).  If more packets are required, it returns -EAGAIN.
 */
static int rxrpc_recvmsg_data(struct socket *sock, struct rxrpc_call *call,
                              struct msghdr *msg, struct iov_iter *iter,
                              size_t len, int flags, size_t *_offset)
{
        struct rxrpc_skb_priv *sp;
        struct sk_buff *skb;
        rxrpc_serial_t serial;
        rxrpc_seq_t hard_ack, top, seq;
        size_t remain;
        bool rx_pkt_last;
        unsigned int rx_pkt_offset, rx_pkt_len;
        int ix, copy, ret = -EAGAIN, ret2;

        if (test_and_clear_bit(RXRPC_CALL_RX_UNDERRUN, &call->flags) &&
            call->ackr_reason)
                rxrpc_send_ack_packet(call, false, NULL);

        rx_pkt_offset = call->rx_pkt_offset;
        rx_pkt_len = call->rx_pkt_len;
        rx_pkt_last = call->rx_pkt_last;

        if (call->state >= RXRPC_CALL_SERVER_ACK_REQUEST) {
                seq = call->rx_hard_ack;
                ret = 1;
                goto done;
        }

        /* Barriers against rxrpc_input_data(). */
        hard_ack = call->rx_hard_ack;
        seq = hard_ack + 1;

        while (top = smp_load_acquire(&call->rx_top),
               before_eq(seq, top)
               ) {
                ix = seq & RXRPC_RXTX_BUFF_MASK;
                skb = call->rxtx_buffer[ix];
                if (!skb) {
                        trace_rxrpc_recvmsg(call, rxrpc_recvmsg_hole, seq,
                                            rx_pkt_offset, rx_pkt_len, 0);
                        break;
                }
                smp_rmb();
                rxrpc_see_skb(skb, rxrpc_skb_seen);
                sp = rxrpc_skb(skb);

                if (!(flags & MSG_PEEK)) {
                        serial = sp->hdr.serial;
                        serial += call->rxtx_annotations[ix] & RXRPC_RX_ANNO_SUBPACKET;
                        trace_rxrpc_receive(call, rxrpc_receive_front,
                                            serial, seq);
                }

                if (msg)
                        sock_recv_timestamp(msg, sock->sk, skb);

                if (rx_pkt_offset == 0) {
                        ret2 = rxrpc_locate_data(call, skb,
                                                 &call->rxtx_annotations[ix],
                                                 &rx_pkt_offset, &rx_pkt_len,
                                                 &rx_pkt_last);
                        trace_rxrpc_recvmsg(call, rxrpc_recvmsg_next, seq,
                                            rx_pkt_offset, rx_pkt_len, ret2);
                        if (ret2 < 0) {
                                ret = ret2;
                                goto out;
                        }
                } else {
                        trace_rxrpc_recvmsg(call, rxrpc_recvmsg_cont, seq,
                                            rx_pkt_offset, rx_pkt_len, 0);
                }

                /* We have to handle short, empty and used-up DATA packets. */
                remain = len - *_offset;
                copy = rx_pkt_len;
                if (copy > remain)
                        copy = remain;
                if (copy > 0) {
                        ret2 = skb_copy_datagram_iter(skb, rx_pkt_offset, iter,
                                                      copy);
                        if (ret2 < 0) {
                                ret = ret2;
                                goto out;
                        }

                        /* handle piecemeal consumption of data packets */
                        rx_pkt_offset += copy;
                        rx_pkt_len -= copy;
                        *_offset += copy;
                }

                if (rx_pkt_len > 0) {
                        trace_rxrpc_recvmsg(call, rxrpc_recvmsg_full, seq,
                                            rx_pkt_offset, rx_pkt_len, 0);
                        ASSERTCMP(*_offset, ==, len);
                        ret = 0;
                        break;
                }

                /* The whole packet has been transferred. */
                if (!(flags & MSG_PEEK))
                        rxrpc_rotate_rx_window(call);
                rx_pkt_offset = 0;
                rx_pkt_len = 0;

                if (rx_pkt_last) {
                        ASSERTCMP(seq, ==, READ_ONCE(call->rx_top));
                        ret = 1;
                        goto out;
                }

                seq++;
        }

out:
        if (!(flags & MSG_PEEK)) {
                call->rx_pkt_offset = rx_pkt_offset;
                call->rx_pkt_len = rx_pkt_len;
                call->rx_pkt_last = rx_pkt_last;
        }
done:
        trace_rxrpc_recvmsg(call, rxrpc_recvmsg_data_return, seq,
                            rx_pkt_offset, rx_pkt_len, ret);
        if (ret == -EAGAIN)
                set_bit(RXRPC_CALL_RX_UNDERRUN, &call->flags);
        return ret;
}

/*
 * Receive a message from an RxRPC socket
 * - we need to be careful about two or more threads calling recvmsg
 *   simultaneously
 */
int rxrpc_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
                  int flags)
{
        struct rxrpc_call *call;
        struct rxrpc_sock *rx = rxrpc_sk(sock->sk);
        struct list_head *l;
        size_t copied = 0;
        long timeo;
        int ret;

        DEFINE_WAIT(wait);

        trace_rxrpc_recvmsg(NULL, rxrpc_recvmsg_enter, 0, 0, 0, 0);

        if (flags & (MSG_OOB | MSG_TRUNC))
                return -EOPNOTSUPP;

        timeo = sock_rcvtimeo(&rx->sk, flags & MSG_DONTWAIT);

try_again:
        lock_sock(&rx->sk);

        /* Return immediately if a client socket has no outstanding calls */
        if (RB_EMPTY_ROOT(&rx->calls) &&
            list_empty(&rx->recvmsg_q) &&
            rx->sk.sk_state != RXRPC_SERVER_LISTENING) {
                release_sock(&rx->sk);
                return -EAGAIN;
        }

        if (list_empty(&rx->recvmsg_q)) {
                ret = -EWOULDBLOCK;
                if (timeo == 0) {
                        call = NULL;
                        goto error_no_call;
                }

                release_sock(&rx->sk);

                /* Wait for something to happen */
                prepare_to_wait_exclusive(sk_sleep(&rx->sk), &wait,
                                          TASK_INTERRUPTIBLE);
                ret = sock_error(&rx->sk);
                if (ret)
                        goto wait_error;

                if (list_empty(&rx->recvmsg_q)) {
                        if (signal_pending(current))
                                goto wait_interrupted;
                        trace_rxrpc_recvmsg(NULL, rxrpc_recvmsg_wait,
                                            0, 0, 0, 0);
                        timeo = schedule_timeout(timeo);
                }
                finish_wait(sk_sleep(&rx->sk), &wait);
                goto try_again;
        }

        /* Find the next call and dequeue it if we're not just peeking.  If we
         * do dequeue it, that comes with a ref that we will need to release.
         */
        write_lock_bh(&rx->recvmsg_lock);
        l = rx->recvmsg_q.next;
        call = list_entry(l, struct rxrpc_call, recvmsg_link);
        if (!(flags & MSG_PEEK))
                list_del_init(&call->recvmsg_link);
        else
                rxrpc_get_call(call, rxrpc_call_got);
        write_unlock_bh(&rx->recvmsg_lock);

        trace_rxrpc_recvmsg(call, rxrpc_recvmsg_dequeue, 0, 0, 0, 0);

        /* We're going to drop the socket lock, so we need to lock the call
         * against interference by sendmsg.
         */
        if (!mutex_trylock(&call->user_mutex)) {
                ret = -EWOULDBLOCK;
                if (flags & MSG_DONTWAIT)
                        goto error_requeue_call;
                ret = -ERESTARTSYS;
                if (mutex_lock_interruptible(&call->user_mutex) < 0)
                        goto error_requeue_call;
        }

        release_sock(&rx->sk);

        if (test_bit(RXRPC_CALL_RELEASED, &call->flags))
                BUG();

        if (test_bit(RXRPC_CALL_HAS_USERID, &call->flags)) {
                if (flags & MSG_CMSG_COMPAT) {
                        unsigned int id32 = call->user_call_ID;

                        ret = put_cmsg(msg, SOL_RXRPC, RXRPC_USER_CALL_ID,
                                       sizeof(unsigned int), &id32);
                } else {
                        unsigned long idl = call->user_call_ID;

                        ret = put_cmsg(msg, SOL_RXRPC, RXRPC_USER_CALL_ID,
                                       sizeof(unsigned long), &idl);
                }
                if (ret < 0)
                        goto error_unlock_call;
        }

        if (msg->msg_name && call->peer) {
                struct sockaddr_rxrpc *srx = msg->msg_name;
                size_t len = sizeof(call->peer->srx);

                memcpy(msg->msg_name, &call->peer->srx, len);
                srx->srx_service = call->service_id;
                msg->msg_namelen = len;
        }

        switch (READ_ONCE(call->state)) {
        case RXRPC_CALL_CLIENT_RECV_REPLY:
        case RXRPC_CALL_SERVER_RECV_REQUEST:
        case RXRPC_CALL_SERVER_ACK_REQUEST:
                ret = rxrpc_recvmsg_data(sock, call, msg, &msg->msg_iter, len,
                                         flags, &copied);
                if (ret == -EAGAIN)
                        ret = 0;

                if (after(call->rx_top, call->rx_hard_ack) &&
                    call->rxtx_buffer[(call->rx_hard_ack + 1) & RXRPC_RXTX_BUFF_MASK])
                        rxrpc_notify_socket(call);
                break;
        default:
                ret = 0;
                break;
        }

        if (ret < 0)
                goto error_unlock_call;

        if (call->state == RXRPC_CALL_COMPLETE) {
                ret = rxrpc_recvmsg_term(call, msg);
                if (ret < 0)
                        goto error_unlock_call;
                if (!(flags & MSG_PEEK))
                        rxrpc_release_call(rx, call);
                msg->msg_flags |= MSG_EOR;
                ret = 1;
        }

        if (ret == 0)
                msg->msg_flags |= MSG_MORE;
        else
                msg->msg_flags &= ~MSG_MORE;
        ret = copied;

error_unlock_call:
        mutex_unlock(&call->user_mutex);
        rxrpc_put_call(call, rxrpc_call_put);
        trace_rxrpc_recvmsg(call, rxrpc_recvmsg_return, 0, 0, 0, ret);
        return ret;

error_requeue_call:
        if (!(flags & MSG_PEEK)) {
                write_lock_bh(&rx->recvmsg_lock);
                list_add(&call->recvmsg_link, &rx->recvmsg_q);
                write_unlock_bh(&rx->recvmsg_lock);
                trace_rxrpc_recvmsg(call, rxrpc_recvmsg_requeue, 0, 0, 0, 0);
        } else {
                rxrpc_put_call(call, rxrpc_call_put);
        }
error_no_call:
        release_sock(&rx->sk);
error_trace:
        trace_rxrpc_recvmsg(call, rxrpc_recvmsg_return, 0, 0, 0, ret);
        return ret;

wait_interrupted:
        ret = sock_intr_errno(timeo);
wait_error:
        finish_wait(sk_sleep(&rx->sk), &wait);
        call = NULL;
        goto error_trace;
}

/**
 * rxrpc_kernel_recv_data - Allow a kernel service to receive data/info
 * @sock: The socket that the call exists on
 * @call: The call to send data through
 * @iter: The buffer to receive into
 * @_len: The amount of data we want to receive (decreased on return)
 * @want_more: True if more data is expected to be read
 * @_abort: Where the abort code is stored if -ECONNABORTED is returned
 * @_service: Where to store the actual service ID (may be upgraded)
 *
 * Allow a kernel service to receive data and pick up information about the
 * state of a call.  Returns 0 if got what was asked for and there's more
 * available, 1 if we got what was asked for and we're at the end of the data
 * and -EAGAIN if we need more data.
 *
 * Note that we may return -EAGAIN to drain empty packets at the end of the
 * data, even if we've already copied over the requested data.
 *
 * *_abort should also be initialised to 0.
 */
int rxrpc_kernel_recv_data(struct socket *sock, struct rxrpc_call *call,
                           struct iov_iter *iter, size_t *_len,
                           bool want_more, u32 *_abort, u16 *_service)
{
        size_t offset = 0;
        int ret;

        _enter("{%d,%s},%zu,%d",
               call->debug_id, rxrpc_call_states[call->state],
               *_len, want_more);

        ASSERTCMP(call->state, !=, RXRPC_CALL_SERVER_SECURING);

        mutex_lock(&call->user_mutex);

        switch (READ_ONCE(call->state)) {
        case RXRPC_CALL_CLIENT_RECV_REPLY:
        case RXRPC_CALL_SERVER_RECV_REQUEST:
        case RXRPC_CALL_SERVER_ACK_REQUEST:
                ret = rxrpc_recvmsg_data(sock, call, NULL, iter,
                                         *_len, 0, &offset);
                *_len -= offset;
                if (ret < 0)
                        goto out;

                /* We can only reach here with a partially full buffer if we
                 * have reached the end of the data.  We must otherwise have a
                 * full buffer or have been given -EAGAIN.
                 */
                if (ret == 1) {
                        if (iov_iter_count(iter) > 0)
                                goto short_data;
                        if (!want_more)
                                goto read_phase_complete;
                        ret = 0;
                        goto out;
                }

                if (!want_more)
                        goto excess_data;
                goto out;

        case RXRPC_CALL_COMPLETE:
                goto call_complete;

        default:
                ret = -EINPROGRESS;
                goto out;
        }

read_phase_complete:
        ret = 1;
out:
        switch (call->ackr_reason) {
        case RXRPC_ACK_IDLE:
                break;
        case RXRPC_ACK_DELAY:
                if (ret != -EAGAIN)
                        break;
                fallthrough;
        default:
                rxrpc_send_ack_packet(call, false, NULL);
        }

        if (_service)
                *_service = call->service_id;
        mutex_unlock(&call->user_mutex);
        _leave(" = %d [%zu,%d]", ret, iov_iter_count(iter), *_abort);
        return ret;

short_data:
        trace_rxrpc_rx_eproto(call, 0, tracepoint_string("short_data"));
        ret = -EBADMSG;
        goto out;
excess_data:
        trace_rxrpc_rx_eproto(call, 0, tracepoint_string("excess_data"));
        ret = -EMSGSIZE;
        goto out;
call_complete:
        *_abort = call->abort_code;
        ret = call->error;
        if (call->completion == RXRPC_CALL_SUCCEEDED) {
                ret = 1;
                if (iov_iter_count(iter) > 0)
                        ret = -ECONNRESET;
        }
        goto out;
}
EXPORT_SYMBOL(rxrpc_kernel_recv_data);

/**
 * rxrpc_kernel_get_reply_time - Get timestamp on first reply packet
 * @sock: The socket that the call exists on
 * @call: The call to query
 * @_ts: Where to put the timestamp
 *
 * Retrieve the timestamp from the first DATA packet of the reply if it is
 * in the ring.  Returns true if successful, false if not.
 */
bool rxrpc_kernel_get_reply_time(struct socket *sock, struct rxrpc_call *call,
                                 ktime_t *_ts)
{
        struct sk_buff *skb;
        rxrpc_seq_t hard_ack, top, seq;
        bool success = false;

        mutex_lock(&call->user_mutex);

        if (READ_ONCE(call->state) != RXRPC_CALL_CLIENT_RECV_REPLY)
                goto out;

        hard_ack = call->rx_hard_ack;
        if (hard_ack != 0)
                goto out;

        seq = hard_ack + 1;
        top = smp_load_acquire(&call->rx_top);
        if (after(seq, top))
                goto out;

        skb = call->rxtx_buffer[seq & RXRPC_RXTX_BUFF_MASK];
        if (!skb)
                goto out;

        *_ts = skb_get_ktime(skb);
        success = true;

out:
        mutex_unlock(&call->user_mutex);
        return success;
}
EXPORT_SYMBOL(rxrpc_kernel_get_reply_time);