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

[Jeff Layton <jlayton@redhat.com>]

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>
---
 utils/mount/network.c |   34 +++++++++++++++++++++++++++-------
 1 files changed, 27 insertions(+), 7 deletions(-)

diff --git a/utils/mount/network.c b/utils/mount/network.c
index c400dd8..ad165f4 100644
--- a/utils/mount/network.c
+++ b/utils/mount/network.c
@@ -1334,9 +1334,26 @@ 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) {
+		errno = EAFNOSUPPORT;
+		return 0;
+	}
+
+	return 1;
+}
+#endif /* IPV6_SUPPORTED */
 
 /*
  * Returns TRUE and fills in @family if a valid NFS protocol option
@@ -1357,15 +1374,15 @@ 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, family, &protocol))
+			return 0;
 	}
 
 	/*
 	 * NFS transport protocol wasn't specified.  Return the
 	 * default address family.
 	 */
-	return 1;
+	return nfs_verify_family(*family);
 }
 
 /*
@@ -1494,8 +1511,11 @@ int nfs_mount_proto_family(struct mount_options *options,
 	*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, family, &protocol))
+			return 0;
+		return nfs_verify_family(*family);
+	}
 
 	/*
 	 * MNT transport protocol wasn't specified.  If the NFS
-- 
1.6.6