[PATCH net v4 2/9] rxrpc: Fix packet encryption error handling
From: David Howells <dhowells@redhat.com>
Date: 2026-07-23 10:03:33
Also in:
lkml
Subsystem:
networking [general], rxrpc sockets (af_rxrpc), the rest, tracing · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, David Howells, Marc Dionne, Linus Torvalds, Steven Rostedt, Masami Hiramatsu
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 <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: Eric Dumazet <edumazet@google.com>
cc: "David S. Miller" <davem@davemloft.net>
cc: Jakub Kicinski <kuba@kernel.org>
cc: Paolo Abeni <pabeni@redhat.com>
cc: Simon Horman <horms@kernel.org>
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) &&