nfs: Convert idmap to use kuids and kgids

Convert nfs_map_name_to_uid to return a kuid_t value.
Convert nfs_map_name_to_gid to return a kgid_t value.
Convert nfs_map_uid_to_name to take a kuid_t paramater.
Convert nfs_map_gid_to_name to take a kgid_t paramater.

Tweak nfs_fattr_map_owner_to_name to use a kuid_t intermediate value.
Tweak nfs_fattr_map_group_to_name to use a kgid_t intermediate value.

Which makes these functions properly handle kuids and kgids, including
erroring of the generated kuid or kgid is invalid.

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

fs/nfs/idmap.c

@@ -97,7 +97,7 @@ static void nfs_fattr_free_group_name(struct nfs_fattr *fattr)
 static bool nfs_fattr_map_owner_name(struct nfs_server *server, struct nfs_fattr *fattr)
 {
 	struct nfs4_string *owner = fattr->owner_name;
-	__u32 uid;
+	kuid_t uid;
 
 	if (!(fattr->valid & NFS_ATTR_FATTR_OWNER_NAME))
 		return false;
@@ -111,7 +111,7 @@ static bool nfs_fattr_map_owner_name(struct nfs_server *server, struct nfs_fattr
 static bool nfs_fattr_map_group_name(struct nfs_server *server, struct nfs_fattr *fattr)
 {
 	struct nfs4_string *group = fattr->group_name;
-	__u32 gid;
+	kgid_t gid;
 
 	if (!(fattr->valid & NFS_ATTR_FATTR_GROUP_NAME))
 		return false;
@@ -837,43 +837,61 @@ idmap_release_pipe(struct inode *inode)
 	nfs_idmap_abort_pipe_upcall(idmap, -EPIPE);
 }
 
-int nfs_map_name_to_uid(const struct nfs_server *server, const char *name, size_t namelen, __u32 *uid)
+int nfs_map_name_to_uid(const struct nfs_server *server, const char *name, size_t namelen, kuid_t *uid)
 {
 	struct idmap *idmap = server->nfs_client->cl_idmap;
+	__u32 id = -1;
+	int ret = 0;
 
-	if (nfs_map_string_to_numeric(name, namelen, uid))
-		return 0;
-	return nfs_idmap_lookup_id(name, namelen, "uid", uid, idmap);
+	if (!nfs_map_string_to_numeric(name, namelen, &id))
+		ret = nfs_idmap_lookup_id(name, namelen, "uid", &id, idmap);
+	if (ret == 0) {
+		*uid = make_kuid(&init_user_ns, id);
+		if (!uid_valid(*uid))
+			ret = -ERANGE;
+	}
+	return ret;
 }
 
-int nfs_map_group_to_gid(const struct nfs_server *server, const char *name, size_t namelen, __u32 *gid)
+int nfs_map_group_to_gid(const struct nfs_server *server, const char *name, size_t namelen, kgid_t *gid)
 {
 	struct idmap *idmap = server->nfs_client->cl_idmap;
+	__u32 id = -1;
+	int ret = 0;
 
-	if (nfs_map_string_to_numeric(name, namelen, gid))
-		return 0;
-	return nfs_idmap_lookup_id(name, namelen, "gid", gid, idmap);
+	if (!nfs_map_string_to_numeric(name, namelen, &id))
+		ret = nfs_idmap_lookup_id(name, namelen, "gid", &id, idmap);
+	if (ret == 0) {
+		*gid = make_kgid(&init_user_ns, id);
+		if (!gid_valid(*gid))
+			ret = -ERANGE;
+	}
+	return ret;
 }
 
-int nfs_map_uid_to_name(const struct nfs_server *server, __u32 uid, char *buf, size_t buflen)
+int nfs_map_uid_to_name(const struct nfs_server *server, kuid_t uid, char *buf, size_t buflen)
 {
 	struct idmap *idmap = server->nfs_client->cl_idmap;
 	int ret = -EINVAL;
+	__u32 id;
 
+	id = from_kuid(&init_user_ns, uid);
 	if (!(server->caps & NFS_CAP_UIDGID_NOMAP))
-		ret = nfs_idmap_lookup_name(uid, "user", buf, buflen, idmap);
+		ret = nfs_idmap_lookup_name(id, "user", buf, buflen, idmap);
 	if (ret < 0)
-		ret = nfs_map_numeric_to_string(uid, buf, buflen);
+		ret = nfs_map_numeric_to_string(id, buf, buflen);
 	return ret;
 }
-int nfs_map_gid_to_group(const struct nfs_server *server, __u32 gid, char *buf, size_t buflen)
+int nfs_map_gid_to_group(const struct nfs_server *server, kgid_t gid, char *buf, size_t buflen)
 {
 	struct idmap *idmap = server->nfs_client->cl_idmap;
 	int ret = -EINVAL;
+	__u32 id;
 
+	id = from_kgid(&init_user_ns, gid);
 	if (!(server->caps & NFS_CAP_UIDGID_NOMAP))
-		ret = nfs_idmap_lookup_name(gid, "group", buf, buflen, idmap);
+		ret = nfs_idmap_lookup_name(id, "group", buf, buflen, idmap);
 	if (ret < 0)
-		ret = nfs_map_numeric_to_string(gid, buf, buflen);
+		ret = nfs_map_numeric_to_string(id, buf, buflen);
 	return ret;
 }

include/linux/nfs_idmap.h

@@ -36,6 +36,7 @@
 #ifndef NFS_IDMAP_H
 #define NFS_IDMAP_H
 
+#include <linux/uidgid.h>
 #include <uapi/linux/nfs_idmap.h>
 
 
@@ -67,10 +68,10 @@ void nfs_fattr_init_names(struct nfs_fattr *fattr,
 void nfs_fattr_free_names(struct nfs_fattr *);
 void nfs_fattr_map_and_free_names(struct nfs_server *, struct nfs_fattr *);
 
-int nfs_map_name_to_uid(const struct nfs_server *, const char *, size_t, __u32 *);
-int nfs_map_group_to_gid(const struct nfs_server *, const char *, size_t, __u32 *);
-int nfs_map_uid_to_name(const struct nfs_server *, __u32, char *, size_t);
-int nfs_map_gid_to_group(const struct nfs_server *, __u32, char *, size_t);
+int nfs_map_name_to_uid(const struct nfs_server *, const char *, size_t, kuid_t *);
+int nfs_map_group_to_gid(const struct nfs_server *, const char *, size_t, kgid_t *);
+int nfs_map_uid_to_name(const struct nfs_server *, kuid_t, char *, size_t);
+int nfs_map_gid_to_group(const struct nfs_server *, kgid_t, char *, size_t);
 
 extern unsigned int nfs_idmap_cache_timeout;
 #endif /* NFS_IDMAP_H */