// 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 #include #include #include #include #include #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(&call->notify_lock); call->notify_rx(sk, call, call->user_call_ID); spin_unlock(&call->notify_lock); } else { spin_lock(&rx->recvmsg_lock); if (list_empty(&call->recvmsg_link)) { rxrpc_get_call(call, rxrpc_call_get_notify_socket); list_add_tail(&call->recvmsg_link, &rx->recvmsg_q); } spin_unlock(&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(""); } /* * 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->completion); BUG(); break; } trace_rxrpc_recvdata(call, rxrpc_recvmsg_terminal, call->ackr_window - 1, call->rx_pkt_offset, call->rx_pkt_len, ret); return ret; } /* * 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 old_consumed = call->rx_consumed, tseq; bool last; int acked; _enter("%d", call->debug_id); skb = skb_dequeue(&call->recvmsg_queue); rxrpc_see_skb(skb, rxrpc_skb_see_rotate); sp = rxrpc_skb(skb); tseq = sp->hdr.seq; serial = sp->hdr.serial; last = sp->hdr.flags & RXRPC_LAST_PACKET; /* Barrier against rxrpc_input_data(). */ if (after(tseq, call->rx_consumed)) smp_store_release(&call->rx_consumed, tseq); rxrpc_free_skb(skb, rxrpc_skb_put_rotate); trace_rxrpc_receive(call, last ? rxrpc_receive_rotate_last : rxrpc_receive_rotate, serial, call->rx_consumed); if (last) set_bit(RXRPC_CALL_RECVMSG_READ_ALL, &call->flags); /* Check to see if there's an ACK that needs sending. */ acked = atomic_add_return(call->rx_consumed - old_consumed, &call->ackr_nr_consumed); if (acked > 8 && !test_and_set_bit(RXRPC_CALL_RX_IS_IDLE, &call->flags)) rxrpc_poke_call(call, rxrpc_call_poke_idle); } /* * Decrypt and verify a DATA packet. */ static int rxrpc_verify_data(struct rxrpc_call *call, struct sk_buff *skb) { struct rxrpc_skb_priv *sp = rxrpc_skb(skb); if (sp->flags & RXRPC_RX_VERIFIED) return 0; return call->security->verify_packet(call, skb); } /* * 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 and if the * call has failed it returns -EIO. */ 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_seq_t seq = 0; size_t remain; unsigned int rx_pkt_offset, rx_pkt_len; int copy, ret = -EAGAIN, ret2; rx_pkt_offset = call->rx_pkt_offset; rx_pkt_len = call->rx_pkt_len; if (rxrpc_call_has_failed(call)) { seq = call->ackr_window - 1; ret = -EIO; goto done; } if (test_bit(RXRPC_CALL_RECVMSG_READ_ALL, &call->flags)) { seq = call->ackr_window - 1; ret = 1; goto done; } /* No one else can be removing stuff from the queue, so we shouldn't * need the Rx lock to walk it. */ skb = skb_peek(&call->recvmsg_queue); while (skb) { rxrpc_see_skb(skb, rxrpc_skb_see_recvmsg); sp = rxrpc_skb(skb); seq = sp->hdr.seq; if (!(flags & MSG_PEEK)) trace_rxrpc_receive(call, rxrpc_receive_front, sp->hdr.serial, seq); if (msg) sock_recv_timestamp(msg, sock->sk, skb); if (rx_pkt_offset == 0) { ret2 = rxrpc_verify_data(call, skb); trace_rxrpc_recvdata(call, rxrpc_recvmsg_next, seq, sp->offset, sp->len, ret2); if (ret2 < 0) { kdebug("verify = %d", ret2); ret = ret2; goto out; } rx_pkt_offset = sp->offset; rx_pkt_len = sp->len; } else { trace_rxrpc_recvdata(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_recvdata(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 (sp->hdr.flags & RXRPC_LAST_PACKET) ret = 1; rx_pkt_offset = 0; rx_pkt_len = 0; skb = skb_peek_next(skb, &call->recvmsg_queue); if (!(flags & MSG_PEEK)) rxrpc_rotate_rx_window(call); } out: if (!(flags & MSG_PEEK)) { call->rx_pkt_offset = rx_pkt_offset; call->rx_pkt_len = rx_pkt_len; } done: trace_rxrpc_recvdata(call, rxrpc_recvmsg_data_return, seq, rx_pkt_offset, rx_pkt_len, ret); if (ret == -EAGAIN) set_bit(RXRPC_CALL_RX_IS_IDLE, &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; unsigned int call_debug_id = 0; size_t copied = 0; long timeo; int ret; DEFINE_WAIT(wait); trace_rxrpc_recvmsg(0, rxrpc_recvmsg_enter, 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(0, rxrpc_recvmsg_wait, 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. */ spin_lock(&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_get_recvmsg); spin_unlock(&rx->recvmsg_lock); call_debug_id = call->debug_id; trace_rxrpc_recvmsg(call_debug_id, rxrpc_recvmsg_dequeue, 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) { size_t len = sizeof(call->dest_srx); memcpy(msg->msg_name, &call->dest_srx, len); msg->msg_namelen = len; } ret = rxrpc_recvmsg_data(sock, call, msg, &msg->msg_iter, len, flags, &copied); if (ret == -EAGAIN) ret = 0; if (ret == -EIO) goto call_failed; if (ret < 0) goto error_unlock_call; if (rxrpc_call_is_complete(call) && skb_queue_empty(&call->recvmsg_queue)) goto call_complete; if (rxrpc_call_has_failed(call)) goto call_failed; rxrpc_notify_socket(call); goto not_yet_complete; call_failed: rxrpc_purge_queue(&call->recvmsg_queue); 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; not_yet_complete: 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_recvmsg); trace_rxrpc_recvmsg(call_debug_id, rxrpc_recvmsg_return, ret); return ret; error_requeue_call: if (!(flags & MSG_PEEK)) { spin_lock(&rx->recvmsg_lock); list_add(&call->recvmsg_link, &rx->recvmsg_q); spin_unlock(&rx->recvmsg_lock); trace_rxrpc_recvmsg(call_debug_id, rxrpc_recvmsg_requeue, 0); } else { rxrpc_put_call(call, rxrpc_call_put_recvmsg); } error_no_call: release_sock(&rx->sk); error_trace: trace_rxrpc_recvmsg(call_debug_id, rxrpc_recvmsg_return, 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},%zu,%d", call->debug_id, *_len, want_more); mutex_lock(&call->user_mutex); ret = rxrpc_recvmsg_data(sock, call, NULL, iter, *_len, 0, &offset); *_len -= offset; if (ret == -EIO) goto call_failed; 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; read_phase_complete: ret = 1; out: if (_service) *_service = call->dest_srx.srx_service; mutex_unlock(&call->user_mutex); _leave(" = %d [%zu,%d]", ret, iov_iter_count(iter), *_abort); return ret; short_data: trace_rxrpc_abort(call->debug_id, rxrpc_recvmsg_short_data, call->cid, call->call_id, call->rx_consumed, 0, -EBADMSG); ret = -EBADMSG; goto out; excess_data: trace_rxrpc_abort(call->debug_id, rxrpc_recvmsg_excess_data, call->cid, call->call_id, call->rx_consumed, 0, -EMSGSIZE); ret = -EMSGSIZE; goto out; call_failed: *_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);