NFS: add support for multiple sec= mount options

This patch adds support for multiple security options which can be
specified using a colon-delimited list of security flavors (the same
syntax as nfsd's exports file).

This is useful, for instance, when NFSv4.x mounts cross SECINFO
boundaries. With this patch a user can use "sec=krb5i,krb5p"
to mount a remote filesystem using krb5i, but can still cross
into krb5p-only exports.

New mounts will try all security options before failing.  NFSv4.x
SECINFO results will be compared against the sec= flavors to
find the first flavor in both lists or if no match is found will
return -EPERM.

Signed-off-by: Weston Andros Adamson <dros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 21 insertions, 11 deletions

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 0eb8dc5792da..b02c4cc7b0a9 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -2873,11 +2873,24 @@ static int nfs4_find_root_sec(struct nfs_server *server, struct nfs_fh *fhandle,
 	int status = -EPERM;
 	size_t i;
 
-	for (i = 0; i < ARRAY_SIZE(flav_array); i++) {
-		status = nfs4_lookup_root_sec(server, fhandle, info, flav_array[i]);
-		if (status == -NFS4ERR_WRONGSEC || status == -EACCES)
-			continue;
-		break;
+	if (server->auth_info.flavor_len > 0) {
+		/* try each flavor specified by user */
+		for (i = 0; i < server->auth_info.flavor_len; i++) {
+			status = nfs4_lookup_root_sec(server, fhandle, info,
+						server->auth_info.flavors[i]);
+			if (status == -NFS4ERR_WRONGSEC || status == -EACCES)
+				continue;
+			break;
+		}
+	} else {
+		/* no flavors specified by user, try default list */
+		for (i = 0; i < ARRAY_SIZE(flav_array); i++) {
+			status = nfs4_lookup_root_sec(server, fhandle, info,
+						      flav_array[i]);
+			if (status == -NFS4ERR_WRONGSEC || status == -EACCES)
+				continue;
+			break;
+		}
 	}
 
 	/*
@@ -2919,9 +2932,6 @@ int nfs4_proc_get_rootfh(struct nfs_server *server, struct nfs_fh *fhandle,
 		status = nfs4_lookup_root(server, fhandle, info);
 		if (status != -NFS4ERR_WRONGSEC)
 			break;
-		/* Did user force a 'sec=' mount option? */
-		if (server->auth_info.flavor_len > 0)
-			break;
 	default:
 		status = nfs4_do_find_root_sec(server, fhandle, info);
 	}
@@ -3179,9 +3189,6 @@ static int nfs4_proc_lookup_common(struct rpc_clnt **clnt, struct inode *dir,
 			err = -EPERM;
 			if (client != *clnt)
 				goto out;
-			/* No security negotiation if the user specified 'sec=' */
-			if (NFS_SERVER(dir)->auth_info.flavor_len > 0)
-				goto out;
 			client = nfs4_create_sec_client(client, dir, name);
 			if (IS_ERR(client))
 				return PTR_ERR(client);
@@ -7942,6 +7949,9 @@ nfs41_find_root_sec(struct nfs_server *server, struct nfs_fh *fhandle,
 			break;
 		}
 
+		if (!nfs_auth_info_match(&server->auth_info, flavor))
+			flavor = RPC_AUTH_MAXFLAVOR;
+
 		if (flavor != RPC_AUTH_MAXFLAVOR) {
 			err = nfs4_lookup_root_sec(server, fhandle,
 						   info, flavor);