userns: Convert fat to use kuid/kgid where appropriate

Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

fs/fat/fat.h

@@ -23,8 +23,8 @@
 #define FAT_ERRORS_RO		3      /* remount r/o on error */
 
 struct fat_mount_options {
-	uid_t fs_uid;
-	gid_t fs_gid;
+	kuid_t fs_uid;
+	kgid_t fs_gid;
 	unsigned short fs_fmask;
 	unsigned short fs_dmask;
 	unsigned short codepage;  /* Codepage for shortname conversions */

fs/fat/file.c

@@ -352,7 +352,7 @@ static int fat_allow_set_time(struct msdos_sb_info *sbi, struct inode *inode)
 {
 	umode_t allow_utime = sbi->options.allow_utime;
 
-	if (current_fsuid() != inode->i_uid) {
+	if (!uid_eq(current_fsuid(), inode->i_uid)) {
 		if (in_group_p(inode->i_gid))
 			allow_utime >>= 3;
 		if (allow_utime & MAY_WRITE)
@@ -407,9 +407,9 @@ int fat_setattr(struct dentry *dentry, struct iattr *attr)
 	}
 
 	if (((attr->ia_valid & ATTR_UID) &&
-	     (attr->ia_uid != sbi->options.fs_uid)) ||
+	     (!uid_eq(attr->ia_uid, sbi->options.fs_uid))) ||
 	    ((attr->ia_valid & ATTR_GID) &&
-	     (attr->ia_gid != sbi->options.fs_gid)) ||
+	     (!gid_eq(attr->ia_gid, sbi->options.fs_gid))) ||
 	    ((attr->ia_valid & ATTR_MODE) &&
 	     (attr->ia_mode & ~FAT_VALID_MODE)))
 		error = -EPERM;

fs/fat/inode.c

@@ -791,10 +791,12 @@ static int fat_show_options(struct seq_file *m, struct dentry *root)
 	struct fat_mount_options *opts = &sbi->options;
 	int isvfat = opts->isvfat;
 
-	if (opts->fs_uid != 0)
-		seq_printf(m, ",uid=%u", opts->fs_uid);
-	if (opts->fs_gid != 0)
-		seq_printf(m, ",gid=%u", opts->fs_gid);
+	if (!uid_eq(opts->fs_uid, GLOBAL_ROOT_UID))
+		seq_printf(m, ",uid=%u",
+				from_kuid_munged(&init_user_ns, opts->fs_uid));
+	if (!gid_eq(opts->fs_gid, GLOBAL_ROOT_GID))
+		seq_printf(m, ",gid=%u",
+				from_kgid_munged(&init_user_ns, opts->fs_gid));
 	seq_printf(m, ",fmask=%04o", opts->fs_fmask);
 	seq_printf(m, ",dmask=%04o", opts->fs_dmask);
 	if (opts->allow_utime)
@@ -1037,12 +1039,16 @@ static int parse_options(struct super_block *sb, char *options, int is_vfat,
 		case Opt_uid:
 			if (match_int(&args[0], &option))
 				return 0;
-			opts->fs_uid = option;
+			opts->fs_uid = make_kuid(current_user_ns(), option);
+			if (!uid_valid(opts->fs_uid))
+				return 0;
 			break;
 		case Opt_gid:
 			if (match_int(&args[0], &option))
 				return 0;
-			opts->fs_gid = option;
+			opts->fs_gid = make_kgid(current_user_ns(), option);
+			if (!gid_valid(opts->fs_gid))
+				return 0;
 			break;
 		case Opt_umask:
 			if (match_octal(&args[0], &option))

init/Kconfig

@@ -952,7 +952,6 @@ config UIDGID_CONVERTED
 	depends on ECRYPT_FS = n
 	depends on EFS_FS = n
 	depends on EXOFS_FS = n
-	depends on FAT_FS = n
 	depends on FUSE_FS = n
 	depends on GFS2_FS = n
 	depends on HFS_FS = n