mountd: Add the missing '$' in auth_unix_ip()

We found this problem because NFS clients to a RHEL6 NFS server were
experiencing periods of ESTALE errors after being mounted and initially
working successfully. Tests were run which snapshotted the nfs/sunrpc
caches before and after the issue, and it was found that the '$'
character
at the beginning of the ID strings, used when in use_ipaddr mode, was
getting
lost:

GOOD, while mount was working:
nfsd 1.2.3.4 $1.2.3.4

BAD, after mount started returning ESTALE:
nfsd 1.2.3.4 1.2.3.4

This would then cause the export checks to fail by passing '1.2.3.4'
instead of '$1.2.3.4' up to rpc.mountd.

The problem appears to be in the auth_unix_ip() function when renewing
the auth.unix.ip cache entry.  It would fail to add the '$' character
back to the beginning of the string used for the domain string,
breaking the use_ipaddr mode.

Signed-off-by: Jose Castillo <jcastillo@redhat.com>
Signed-off-by: Steve Dickson <steved@redhat.com>

1 files changed, 6 insertions, 4 deletions

diff --git a/utils/mountd/cache.c b/utils/mountd/cache.c
index 978698d..e1027f3 100644
--- a/utils/mountd/cache.c
+++ b/utils/mountd/cache.c
@@ -80,7 +80,7 @@ static void auth_unix_ip(FILE *f)
 	 */
 	char *cp;
 	char class[20];
-	char ipaddr[INET6_ADDRSTRLEN];
+	char ipaddr[INET6_ADDRSTRLEN + 1];
 	char *client = NULL;
 	struct addrinfo *tmp = NULL;
 	if (readline(fileno(f), &lbuf, &lbuflen) != 1)
@@ -94,7 +94,7 @@ static void auth_unix_ip(FILE *f)
 	    strcmp(class, "nfsd") != 0)
 		return;
 
-	if (qword_get(&cp, ipaddr, sizeof(ipaddr)) <= 0)
+	if (qword_get(&cp, ipaddr, sizeof(ipaddr) - 1) <= 0)
 		return;
 
 	tmp = host_pton(ipaddr);
@@ -116,9 +116,11 @@ static void auth_unix_ip(FILE *f)
 	qword_print(f, "nfsd");
 	qword_print(f, ipaddr);
 	qword_printtimefrom(f, DEFAULT_TTL);
-	if (use_ipaddr)
+	if (use_ipaddr) {
+		memmove(ipaddr + 1, ipaddr, strlen(ipaddr) + 1);
+		ipaddr[0] = '$';
 		qword_print(f, ipaddr);
-	else if (client)
+	} else if (client)
 		qword_print(f, *client?client:"DEFAULT");
 	qword_eol(f);
 	xlog(D_CALL, "auth_unix_ip: client %p '%s'", client, client?client: "DEFAULT");