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SUNRPC: timeout and cancel TLS handshake with -ETIMEDOUT

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[ Upstream commit d7bdd849ef ]

We've noticed a situation where an unstable TCP connection can cause the
TLS handshake to timeout waiting for userspace to complete it.  When this
happens, we don't want to return from xs_tls_handshake_sync() with zero, as
this will cause the upper xprt to be set CONNECTED, and subsequent attempts
to transmit will be returned with -EPIPE.  The sunrpc machine does not
recover from this situation and will spin attempting to transmit.

The return value of tls_handshake_cancel() can be used to detect a race
with completion:

 * tls_handshake_cancel - cancel a pending handshake
 * Return values:
 *   %true - Uncompleted handshake request was canceled
 *   %false - Handshake request already completed or not found

If true, we do not want the upper xprt to be connected, so return
-ETIMEDOUT.  If false, its possible the handshake request was lost and
that may be the reason for our timeout.  Again we do not want the upper
xprt to be connected, so return -ETIMEDOUT.

Ensure that we alway return an error from xs_tls_handshake_sync() if we
call tls_handshake_cancel().

Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Fixes: 75eb6af7ac ("SUNRPC: Add a TCP-with-TLS RPC transport class")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Benjamin Coddington
2024-11-15 08:59:36 -05:00
committed by Greg Kroah-Hartman
parent 3811172e8c
commit 931be6b738
1 changed files with 4 additions and 5 deletions
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net/sunrpc/xprtsock.c
+4 -5
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@@ -2596,11 +2596,10 @@ static int xs_tls_handshake_sync(struct rpc_xprt *lower_xprt, struct xprtsec_par
rc = wait_for_completion_interruptible_timeout(&lower_transport->handshake_done,
XS_TLS_HANDSHAKE_TO);
if (rc <= 0) {
if (!tls_handshake_cancel(sk)) {
if (rc == 0)
rc = -ETIMEDOUT;
goto out_put_xprt;
}
tls_handshake_cancel(sk);
if (rc == 0)
rc = -ETIMEDOUT;
goto out_put_xprt;
}
rc = lower_transport->xprt_err;