From d7bdd849ef1b681da03ac05ca0957b2cbe2d24b6 Mon Sep 17 00:00:00 2001 From: Benjamin Coddington Date: Fri, 15 Nov 2024 08:59:36 -0500 Subject: [PATCH] SUNRPC: timeout and cancel TLS handshake with -ETIMEDOUT 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 Reviewed-by: Chuck Lever Fixes: 75eb6af7acdf ("SUNRPC: Add a TCP-with-TLS RPC transport class") Signed-off-by: Trond Myklebust --- net/sunrpc/xprtsock.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c index 31bc046e285021..fecc8b8fa26618 100644 --- a/net/sunrpc/xprtsock.c +++ b/net/sunrpc/xprtsock.c @@ -2616,11 +2616,10 @@ 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;