tls: Fix tls_sw_sendmsg error handling

Commit Message

Benjamin Coddington Jan. 4, 2025, 3:29 p.m. UTC

We've noticed that NFS can hang when using RPC over TLS on an unstable
connection, and investigation shows that the RPC layer is stuck in a tight
loop attempting to transmit, but forever getting -EBADMSG back from the
underlying network.  The loop begins when tcp_sendmsg_locked() returns
-EPIPE to tls_tx_records(), but that error is converted to -EBADMSG when
calling the socket's error reporting handler.

Instead of converting errors from tcp_sendmsg_locked(), let's pass them
along in this path.  The RPC layer handles -EPIPE by reconnecting the
transport, which prevents the endless attempts to transmit on a broken
connection.

Signed-off-by: Benjamin Coddington <[e-mail]>
---
 net/tls/tls_sw.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)


base-commit: 0bc21e701a6ffacfdde7f04f87d664d82e8a13bf

Comments

Jakub Kicinski Jan. 7, 2025, 2:36 a.m. UTC | #1

On Sat,  4 Jan 2025 10:29:45 -0500 Benjamin Coddington wrote:
> We've noticed that NFS can hang when using RPC over TLS on an unstable
> connection, and investigation shows that the RPC layer is stuck in a tight
> loop attempting to transmit, but forever getting -EBADMSG back from the
> underlying network.  The loop begins when tcp_sendmsg_locked() returns
> -EPIPE to tls_tx_records(), but that error is converted to -EBADMSG when
> calling the socket's error reporting handler.
> 
> Instead of converting errors from tcp_sendmsg_locked(), let's pass them
> along in this path.  The RPC layer handles -EPIPE by reconnecting the
> transport, which prevents the endless attempts to transmit on a broken
> connection.

LGTM, only question in my mind is whether we should send this to stable.
Any preference?

Patch

diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index bbf26cc4f6ee..7bcc9b4408a2 100644
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -458,7 +458,7 @@  int tls_tx_records(struct sock *sk, int flags)
 
 tx_err:
 	if (rc < 0 && rc != -EAGAIN)
-		tls_err_abort(sk, -EBADMSG);
+		tls_err_abort(sk, rc);
 
 	return rc;
 }