Patch "NFS: Don't drop CB requests with invalid principals" has been added to the 4.7-stable tree

This is a note to let you know that I've just added the patch titled

NFS: Don't drop CB requests with invalid principals

to the 4.7-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
nfs-don-t-drop-cb-requests-with-invalid-principals.patch
and it can be found in the queue-4.7 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Chuck Lever <[email protected]>
Date: Wed, 29 Jun 2016 13:55:22 -0400
Subject: NFS: Don't drop CB requests with invalid principals

From: Chuck Lever <[email protected]>

commit a4e187d83d88eeaba6252aac0a2ffe5eaa73a818 upstream.

Before commit 778be232a207 ("NFS do not find client in NFSv4 pg_authenticate"), the Linux callback server replied with RPC_AUTH_ERROR / RPC_AUTH_BADCRED, instead of dropping the CB request. Let's restore that behavior so the server has a chance to do something useful about it, and provide a warning that helps admins correct the problem.

---
 fs/nfs/callback_xdr.c |    6 +++++-
 net/sunrpc/svc.c      |    5 +++++
 2 files changed, 10 insertions(+), 1 deletion(-)

@@ -925,7 +925,7 @@ static __be32 nfs4_callback_compound(str
 	if (hdr_arg.minorversion == 0) {
 		cps.clp = nfs4_find_client_ident(SVC_NET(rqstp), hdr_arg.cb_ident);
 		if (!cps.clp || !check_gss_callback_principal(cps.clp, rqstp))
-			return rpc_drop_reply;
+			goto out_invalidcred;
 	}
 
 	cps.minorversion = hdr_arg.minorversion;

@@ -953,6 +953,10 @@ static __be32 nfs4_callback_compound(str
 	nfs_put_client(cps.clp);
 	dprintk("%s: done, status = %u\n", __func__, ntohl(status));
 	return rpc_success;
+
+out_invalidcred:
+	pr_warn_ratelimited("NFS: NFSv4 callback contains invalid cred\n");
+	return rpc_autherr_badcred;
 }
 
 /*

@@ -1194,6 +1194,11 @@ svc_process_common(struct svc_rqst *rqst
 				procp->pc_release(rqstp, NULL, rqstp->rq_resp);
 			goto dropit;
 		}
+		if (*statp == rpc_autherr_badcred) {
+			if (procp->pc_release)
+				procp->pc_release(rqstp, NULL, rqstp->rq_resp);
+			goto err_bad_auth;
+		}
 		if (*statp == rpc_success &&
 		    (xdr = procp->pc_encode) &&
 		    !xdr(rqstp, resv->iov_base+resv->iov_len, rqstp->rq_resp)) {

Patches currently in stable-queue which might be from [email protected] are

queue-4.7/xprtrdma-remove-fmrs-from-the-unmap-list-after-unmapping.patch queue-4.7/svc-avoid-garbage-replies-when-pc_func-returns-rpc_drop_reply.patch queue-4.7/nfs-don-t-drop-cb-requests-with-invalid-principals.patch