userns: Convert usb functionfs to use kuid/kgid where appropriate

Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Felipe Balbi <balbi@ti.com>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

drivers/usb/gadget/f_fs.c

@@ -220,8 +220,8 @@ struct ffs_data {
 	/* File permissions, written once when fs is mounted */
 	struct ffs_file_perms {
 		umode_t				mode;
-		uid_t				uid;
-		gid_t				gid;
+		kuid_t				uid;
+		kgid_t				gid;
 	}				file_perms;
 
 	/*
@@ -1143,10 +1143,19 @@ static int ffs_fs_parse_opts(struct ffs_sb_fill_data *data, char *opts)
 			break;
 
 		case 3:
-			if (!memcmp(opts, "uid", 3))
-				data->perms.uid = value;
+			if (!memcmp(opts, "uid", 3)) {
+				data->perms.uid = make_kuid(current_user_ns(), value);
+				if (!uid_valid(data->perms.uid)) {
+					pr_err("%s: unmapped value: %lu\n", opts, value);
+					return -EINVAL;
+				}
+			}
 			else if (!memcmp(opts, "gid", 3))
-				data->perms.gid = value;
+				data->perms.gid = make_kgid(current_user_ns(), value);
+				if (!gid_valid(data->perms.gid)) {
+					pr_err("%s: unmapped value: %lu\n", opts, value);
+					return -EINVAL;
+				}
 			else
 				goto invalid;
 			break;
@@ -1175,8 +1184,8 @@ ffs_fs_mount(struct file_system_type *t, int flags,
 	struct ffs_sb_fill_data data = {
 		.perms = {
 			.mode = S_IFREG | 0600,
-			.uid = 0,
-			.gid = 0
+			.uid = GLOBAL_ROOT_UID,
+			.gid = GLOBAL_ROOT_GID,
 		},
 		.root_mode = S_IFDIR | 0500,
 	};

init/Kconfig

@@ -932,7 +932,6 @@ config UIDGID_CONVERTED
 	depends on NET_9P = n
 
 	# Filesystems
-	depends on USB_FUNCTIONFS = n
 	depends on DEVTMPFS = n
 	depends on XENFS = n