@@ -272,13 +272,8 @@ static int mknod_ptmx(struct super_block *sb)
struct dentry *root = sb->s_root;
struct pts_fs_info *fsi = DEVPTS_SB(sb);
struct pts_mount_opts *opts = &fsi->mount_opts;
- kuid_t root_uid;
- kgid_t root_gid;
-
- root_uid = make_kuid(current_user_ns(), 0);
- root_gid = make_kgid(current_user_ns(), 0);
- if (!uid_valid(root_uid) || !gid_valid(root_gid))
- return -EINVAL;
+ kuid_t ptmx_uid = current_fsuid();
+ kgid_t ptmx_gid = current_fsgid();
inode_lock(d_inode(root));
@@ -309,8 +304,8 @@ static int mknod_ptmx(struct super_block *sb)
mode = S_IFCHR|opts->ptmxmode;
init_special_inode(inode, mode, MKDEV(TTYAUX_MAJOR, 2));
- inode->i_uid = root_uid;
- inode->i_gid = root_gid;
+ inode->i_uid = ptmx_uid;
+ inode->i_gid = ptmx_gid;
d_add(dentry, inode);
In 99.99% of the cases only root in a user namespace can mount /dev/pts and in those cases the owner of /dev/pts/ptmx will remain root.root In the oddball case where someone else has CAP_SYS_ADMIN this code modifies the /dev/pts mount code to use current_fsuid and current_fsgid as the values to use when creating the /dev/ptmx inode. As is done when any other file is created. This is a code simplification, and it allows running without a root user entirely. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> --- fs/devpts/inode.c | 13 ++++--------- 1 file changed, 4 insertions(+), 9 deletions(-)