In rxrpc_send_data(), if ->secure_packet() returns an error, the code currently just jumps to out: and returns the error to the app on the assumption that any error returned by this is automatically fatal for the call, and may even have corrupted the transmission queue - but leaving it to userspace to deal with. Nothing stops the application from retrying the sendmsg(), which will try to encrypt the buffer again, and might succeed with a corrupt buffer. Fix rxrpc_send_data() in the following ways: (1) If -ENOMEM is returned, assume we never got as far as the encryption and that the operation is retryable. In which case, jump to maybe_error_rewind and, if we've copied data into the last packet, remove a byte from it so that we don't tell the caller that we've completed the transmission phase. (2) If any other error occurs, set the TX_ERROR flag on the call and return that error directly; on all subsequent attempts to add data to the call, return -EIO. The app must then abort the call to get rid of it (this allows the app to choose the abort code to use). Fixes: 17926a79320a ("[AF_RXRPC]: Provide secure RxRPC sockets for use by userspace and kernel both") Closes: https://sashiko.dev/#/patchset/20260702144919.172295-1-dhowells%40redhat.com Signed-off-by: David Howells cc: Marc Dionne cc: Eric Dumazet cc: "David S. Miller" cc: Jakub Kicinski cc: Paolo Abeni cc: Simon Horman cc: linux-afs@lists.infradead.org cc: stable@kernel.org --- include/trace/events/rxrpc.h | 1 + net/rxrpc/ar-internal.h | 1 + net/rxrpc/sendmsg.c | 39 +++++++++++++++++++++++++++++++----- 3 files changed, 36 insertions(+), 5 deletions(-) diff --git a/include/trace/events/rxrpc.h b/include/trace/events/rxrpc.h index 704a10de6670..8f3e3967885a 100644 --- a/include/trace/events/rxrpc.h +++ b/include/trace/events/rxrpc.h @@ -148,6 +148,7 @@ EM(rxrpc_eproto_wrong_security, "wrong-sec") \ EM(rxrpc_recvmsg_excess_data, "recvmsg-excess") \ EM(rxrpc_recvmsg_short_data, "recvmsg-short") \ + EM(rxrpc_sendmsg_tx_error, "tx-error") \ E_(rxrpc_sendmsg_late_send, "sendmsg-late") #define rxrpc_call_poke_traces \ diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h index 865f05fe37ab..a6f830c1621f 100644 --- a/net/rxrpc/ar-internal.h +++ b/net/rxrpc/ar-internal.h @@ -642,6 +642,7 @@ enum rxrpc_call_flag { RXRPC_CALL_TX_LAST, /* Last packet in Tx buffer (at rxtx_top) */ RXRPC_CALL_TX_ALL_ACKED, /* Last packet has been hard-acked */ RXRPC_CALL_TX_NO_MORE, /* No more data to transmit (MSG_MORE deasserted) */ + RXRPC_CALL_TX_ERROR, /* Terminal error; call needs abort */ RXRPC_CALL_SEND_PING, /* A ping will need to be sent */ RXRPC_CALL_RETRANS_TIMEOUT, /* Retransmission due to timeout occurred */ RXRPC_CALL_BEGAN_RX_TIMER, /* We began the expect_rx_by timer */ diff --git a/net/rxrpc/sendmsg.c b/net/rxrpc/sendmsg.c index 4c754f78ece9..d117a25b031d 100644 --- a/net/rxrpc/sendmsg.c +++ b/net/rxrpc/sendmsg.c @@ -330,12 +330,18 @@ static int rxrpc_send_data(struct rxrpc_sock *rx, bool more = msg->msg_flags & MSG_MORE; int ret, copied = 0; - if (test_bit(RXRPC_CALL_TX_NO_MORE, &call->flags)) { + if (unlikely(test_bit(RXRPC_CALL_TX_NO_MORE, &call->flags))) { trace_rxrpc_abort(call->debug_id, rxrpc_sendmsg_late_send, call->cid, call->call_id, call->rx_consumed, 0, -EPROTO); return -EPROTO; } + if (unlikely(test_bit(RXRPC_CALL_TX_ERROR, &call->flags))) { + trace_rxrpc_abort(call->debug_id, rxrpc_sendmsg_tx_error, + call->cid, call->call_id, call->rx_consumed, + 0, -EIO); + return -EIO; + } timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT); @@ -440,12 +446,21 @@ static int rxrpc_send_data(struct rxrpc_sock *rx, /* add the packet to the send queue if it's now full */ if (!txb->space || (msg_data_left(msg) == 0 && !more)) { - if (msg_data_left(msg) == 0 && !more) - txb->flags |= RXRPC_LAST_PACKET; - + /* Do any required crypto. If this fails, it could + * have corrupted the txbuf content with a partial + * encrypt. Assume that ENOMEM is retryable, but + * everything else is terminal. + */ ret = call->security->secure_packet(call, txb); - if (ret < 0) + if (ret < 0) { + if (ret == -ENOMEM) + goto maybe_error_rewind; + set_bit(RXRPC_CALL_TX_ERROR, &call->flags); goto out; + } + + if (msg_data_left(msg) == 0 && !more) + txb->flags |= RXRPC_LAST_PACKET; rxrpc_queue_packet(rx, call, txb, notify_end_tx); txb = NULL; } @@ -463,6 +478,20 @@ static int rxrpc_send_data(struct rxrpc_sock *rx, _leave(" = %d", call->error); return call->error; +maybe_error_rewind: + /* If we got a retryable error after copying all the supplied data into + * the last packet, we need to rewind the buffer by one byte so the + * caller knows they need to retry. + */ + if (copied && !more && !msg_data_left(msg)) { + txb->space += 1; + txb->len -= 1; + txb->offset -= 1; + copied -= 1; + if (call->tx_total_len != -1) + call->tx_total_len += 1; + iov_iter_revert(&msg->msg_iter, 1); + } maybe_error: if (copied) { if (rxrpc_call_is_complete(call) &&