mount.nfs: return error if proto= option specified IPv6 when IPv6 isn't supported

Right now, there's nothing that expressly forbids someone from
specifying proto=tcp6 for instance, even when nfs-utils it built without
IPv6 support. This may not work well if (for instance) they are using
NFSv3, since statd won't support IPv6. Explicitly return an error if
someone specifies an IPv6 proto= or mountproto= option and IPv6 isn't
supported.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Steve Dickson <steved@redhat.com>

1 files changed, 43 insertions, 16 deletions

diff --git a/utils/mount/network.c b/utils/mount/network.c
index c400dd8..a12fbe2 100644
--- a/utils/mount/network.c
+++ b/utils/mount/network.c
@@ -1334,21 +1334,36 @@ nfs_nfs_port(struct mount_options *options, unsigned long *port)
 
 #ifdef IPV6_SUPPORTED
 sa_family_t	config_default_family = AF_UNSPEC;
-#else
+
+static int
+nfs_verify_family(sa_family_t family)
+{
+	return 1;
+}
+#else /* IPV6_SUPPORTED */
 sa_family_t	config_default_family = AF_INET;
-#endif
+
+static int
+nfs_verify_family(sa_family_t family)
+{
+	if (family != AF_INET)
+		return 0;
+
+	return 1;
+}
+#endif /* IPV6_SUPPORTED */
 
 /*
  * Returns TRUE and fills in @family if a valid NFS protocol option
- * is found, or FALSE if the option was specified with an invalid value.
+ * is found, or FALSE if the option was specified with an invalid value
+ * or if the protocol family isn't supported. On error, errno is set.
  */
 int nfs_nfs_proto_family(struct mount_options *options,
 				sa_family_t *family)
 {
 	unsigned long protocol;
 	char *option;
-
-	*family = config_default_family;
+	sa_family_t tmp_family = config_default_family;
 
 	switch (po_rightmost(options, nfs_transport_opttbl)) {
 	case 0:	/* udp */
@@ -1357,15 +1372,18 @@ int nfs_nfs_proto_family(struct mount_options *options,
 		return 1;
 	case 2: /* proto */
 		option = po_get(options, "proto");
-		if (option != NULL)
-			return nfs_get_proto(option, family, &protocol);
+		if (option != NULL &&
+		    !nfs_get_proto(option, &tmp_family, &protocol))
+			goto out_err;
 	}
 
-	/*
-	 * NFS transport protocol wasn't specified.  Return the
-	 * default address family.
-	 */
+	if (!nfs_verify_family(tmp_family))
+		goto out_err;
+	*family = tmp_family;
 	return 1;
+out_err:
+	errno = EAFNOSUPPORT;
+	return 0;
 }
 
 /*
@@ -1483,19 +1501,25 @@ nfs_mount_port(struct mount_options *options, unsigned long *port)
 
 /*
  * Returns TRUE and fills in @family if a valid MNT protocol option
- * is found, or FALSE if the option was specified with an invalid value.
+ * is found, or FALSE if the option was specified with an invalid value
+ * or if the protocol family isn't supported. On error, errno is set.
  */
 int nfs_mount_proto_family(struct mount_options *options,
 				sa_family_t *family)
 {
 	unsigned long protocol;
 	char *option;
-
-	*family = config_default_family;
+	sa_family_t tmp_family = config_default_family;
 
 	option = po_get(options, "mountproto");
-	if (option != NULL)
-		return nfs_get_proto(option, family, &protocol);
+	if (option != NULL) {
+		if (!nfs_get_proto(option, &tmp_family, &protocol))
+			goto out_err;
+		if (!nfs_verify_family(tmp_family))
+			goto out_err;
+		*family = tmp_family;
+		return 1;
+	}
 
 	/*
 	 * MNT transport protocol wasn't specified.  If the NFS
@@ -1504,6 +1528,9 @@ int nfs_mount_proto_family(struct mount_options *options,
 	 * NFS.
 	 */
 	return nfs_nfs_proto_family(options, family);
+out_err:
+	errno = EAFNOSUPPORT;
+	return 0;
 }
 
 /**