userns: Convert hugetlbfs to use kuid/kgid where appropriate

Note sysctl_hugetlb_shm_group can only be written in the root user
in the initial user namespace, so we can assume sysctl_hugetlb_shm_group
is in the initial user namespace.

Cc: William Irwin <wli@holomorphy.com>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

fs/hugetlbfs/inode.c

@@ -42,8 +42,8 @@ static const struct inode_operations hugetlbfs_dir_inode_operations;
 static const struct inode_operations hugetlbfs_inode_operations;
 
 struct hugetlbfs_config {
-	uid_t   uid;
-	gid_t   gid;
+	kuid_t   uid;
+	kgid_t   gid;
 	umode_t mode;
 	long	nr_blocks;
 	long	nr_inodes;
@@ -785,13 +785,17 @@ hugetlbfs_parse_options(char *options, struct hugetlbfs_config *pconfig)
 		case Opt_uid:
 			if (match_int(&args[0], &option))
  				goto bad_val;
-			pconfig->uid = option;
+			pconfig->uid = make_kuid(current_user_ns(), option);
+			if (!uid_valid(pconfig->uid))
+				goto bad_val;
 			break;
 
 		case Opt_gid:
 			if (match_int(&args[0], &option))
  				goto bad_val;
-			pconfig->gid = option;
+			pconfig->gid = make_kgid(current_user_ns(), option);
+			if (!gid_valid(pconfig->gid))
+				goto bad_val;
 			break;
 
 		case Opt_mode:
@@ -924,7 +928,9 @@ static struct vfsmount *hugetlbfs_vfsmount;
 
 static int can_do_hugetlb_shm(void)
 {
-	return capable(CAP_IPC_LOCK) || in_group_p(sysctl_hugetlb_shm_group);
+	kgid_t shm_group;
+	shm_group = make_kgid(&init_user_ns, sysctl_hugetlb_shm_group);
+	return capable(CAP_IPC_LOCK) || in_group_p(shm_group);
 }
 
 struct file *hugetlb_file_setup(const char *name, unsigned long addr,

init/Kconfig

@@ -954,7 +954,6 @@ config UIDGID_CONVERTED
 	depends on HFS_FS = n
 	depends on HFSPLUS_FS = n
 	depends on HPFS_FS = n
-	depends on HUGETLBFS = n
 	depends on ISO9660_FS = n
 	depends on JFFS2_FS = n
 	depends on JFS_FS = n