From 7c9526b1e36c4ead68cd0caa2aac02374b490ddc Mon Sep 17 00:00:00 2001
From: Chuck Lever <chuck.lever@oracle.com>
Date: Tue, 29 Nov 2016 11:04:34 -0500
Subject: [PATCH] svcauth_gss: Close connection when dropping an incoming
 message

commit 4d712ef1db05c3aa5c3b690a50c37ebad584c53f upstream.

S5.3.3.1 of RFC 2203 requires that an incoming GSS-wrapped message
whose sequence number lies outside the current window is dropped.
The rationale is:

  The reason for discarding requests silently is that the server
  is unable to determine if the duplicate or out of range request
  was due to a sequencing problem in the client, network, or the
  operating system, or due to some quirk in routing, or a replay
  attack by an intruder.  Discarding the request allows the client
  to recover after timing out, if indeed the duplication was
  unintentional or well intended.

However, clients may rely on the server dropping the connection to
indicate that a retransmit is needed. Without a connection reset, a
client can wait forever without retransmitting, and the workload
just stops dead. I've reproduced this behavior by running xfstests
generic/323 on an NFSv4.0 mount with proto=rdma and sec=krb5i.

To address this issue, have the server close the connection when it
silently discards an incoming message due to a GSS sequence number
problem.

There are a few other places where the server will never reply.
Change those spots in a similar fashion.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/net/sunrpc/auth_gss/svcauth_gss.c b/net/sunrpc/auth_gss/svcauth_gss.c
index a16b5a3e983c..74a1b77d3697 100644
--- a/net/sunrpc/auth_gss/svcauth_gss.c
+++ b/net/sunrpc/auth_gss/svcauth_gss.c
@@ -1541,7 +1541,7 @@ complete:
 	ret = SVC_COMPLETE;
 	goto out;
 drop:
-	ret = SVC_DROP;
+	ret = SVC_CLOSE;
 out:
 	if (rsci)
 		cache_put(&rsci->h, sn->rsc_cache);
diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
index c5b0cb4f4056..463d417ed77c 100644
--- a/net/sunrpc/svc.c
+++ b/net/sunrpc/svc.c
@@ -1138,8 +1138,7 @@ svc_process_common(struct svc_rqst *rqstp, struct kvec *argv, struct kvec *resv)
 	case SVC_DENIED:
 		goto err_bad_auth;
 	case SVC_CLOSE:
-		if (test_bit(XPT_TEMP, &rqstp->rq_xprt->xpt_flags))
-			svc_close_xprt(rqstp->rq_xprt);
+		goto close;
 	case SVC_DROP:
 		goto dropit;
 	case SVC_COMPLETE:
@@ -1229,7 +1228,7 @@ svc_process_common(struct svc_rqst *rqstp, struct kvec *argv, struct kvec *resv)
 
  sendit:
 	if (svc_authorise(rqstp))
-		goto dropit;
+		goto close;
 	return 1;		/* Caller can now send it */
 
  dropit:
@@ -1237,11 +1236,16 @@ svc_process_common(struct svc_rqst *rqstp, struct kvec *argv, struct kvec *resv)
 	dprintk("svc: svc_process dropit\n");
 	return 0;
 
+ close:
+	if (test_bit(XPT_TEMP, &rqstp->rq_xprt->xpt_flags))
+		svc_close_xprt(rqstp->rq_xprt);
+	dprintk("svc: svc_process close\n");
+	return 0;
+
 err_short_len:
 	svc_printk(rqstp, "short len %Zd, dropping request\n",
 			argv->iov_len);
-
-	goto dropit;			/* drop request */
+	goto close;
 
 err_bad_rpc:
 	serv->sv_stats->rpcbadfmt++;
-- 
2.12.0