nfsd: Modify nfsd4_cb_sec to use kuids and kgids

Change uid and gid in struct nfsd4_cb_sec to be of type kuid_t and
kgid_t.

In nfsd4_decode_cb_sec when reading uids and gids off the wire convert
them to kuids and kgids, and if they don't convert to valid kuids or
valid kuids ignore RPC_AUTH_UNIX and don't fill in any of the fields.

Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

fs/nfsd/nfs4xdr.c

@@ -464,9 +464,16 @@ static __be32 nfsd4_decode_cb_sec(struct nfsd4_compoundargs *argp, struct nfsd4_
 			READ32(dummy);
 			READ_BUF(dummy * 4);
 			if (cbs->flavor == (u32)(-1)) {
-				cbs->uid = uid;
-				cbs->gid = gid;
-				cbs->flavor = RPC_AUTH_UNIX;
+				kuid_t kuid = make_kuid(&init_user_ns, uid);
+				kgid_t kgid = make_kgid(&init_user_ns, gid);
+				if (uid_valid(kuid) && gid_valid(kgid)) {
+					cbs->uid = kuid;
+					cbs->gid = kgid;
+					cbs->flavor = RPC_AUTH_UNIX;
+				} else {
+					dprintk("RPC_AUTH_UNIX with invalid"
+						"uid or gid ignoring!\n");
+				}
 			}
 			break;
 		case RPC_AUTH_GSS:

fs/nfsd/state.h

@@ -152,8 +152,8 @@ struct nfsd4_channel_attrs {
 
 struct nfsd4_cb_sec {
 	u32	flavor; /* (u32)(-1) used to mean "no valid flavor" */
-	u32	uid;
-	u32	gid;
+	kuid_t	uid;
+	kgid_t	gid;
 };
 
 struct nfsd4_create_session {