mount: consolidate permission checks
... and ask for global CAP_SYS_ADMIN only for superblock-level remounts
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/namespace.c b/fs/namespace.c
index edac42c..269919f 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1300,24 +1300,6 @@
#endif
-static int mount_is_safe(struct path *path)
-{
- if (may_mount())
- return 0;
- return -EPERM;
-#ifdef notyet
- if (S_ISLNK(path->dentry->d_inode->i_mode))
- return -EPERM;
- if (path->dentry->d_inode->i_mode & S_ISVTX) {
- if (current_uid() != path->dentry->d_inode->i_uid)
- return -EPERM;
- }
- if (inode_permission(path->dentry->d_inode, MAY_WRITE))
- return -EPERM;
- return 0;
-#endif
-}
-
static bool mnt_ns_loop(struct path *path)
{
/* Could bind mounting the mount namespace inode cause a
@@ -1640,9 +1622,6 @@
int type;
int err = 0;
- if (!may_mount())
- return -EPERM;
-
if (path->dentry != path->mnt->mnt_root)
return -EINVAL;
@@ -1676,9 +1655,7 @@
LIST_HEAD(umount_list);
struct path old_path;
struct mount *mnt = NULL, *old;
- int err = mount_is_safe(path);
- if (err)
- return err;
+ int err;
if (!old_name || !*old_name)
return -EINVAL;
err = kern_path(old_name, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &old_path);
@@ -1755,9 +1732,6 @@
struct super_block *sb = path->mnt->mnt_sb;
struct mount *mnt = real_mount(path->mnt);
- if (!capable(CAP_SYS_ADMIN))
- return -EPERM;
-
if (!check_mnt(mnt))
return -EINVAL;
@@ -1771,6 +1745,8 @@
down_write(&sb->s_umount);
if (flags & MS_BIND)
err = change_mount_flags(path->mnt, flags);
+ else if (!capable(CAP_SYS_ADMIN))
+ err = -EPERM;
else
err = do_remount_sb(sb, flags, data, 0);
if (!err) {
@@ -1803,9 +1779,7 @@
struct path old_path, parent_path;
struct mount *p;
struct mount *old;
- int err = 0;
- if (!may_mount())
- return -EPERM;
+ int err;
if (!old_name || !*old_name)
return -EINVAL;
err = kern_path(old_name, LOOKUP_FOLLOW, &old_path);
@@ -1947,9 +1921,6 @@
if (!fstype)
return -EINVAL;
- if (!may_mount())
- return -EPERM;
-
type = get_fs_type(fstype);
if (!type)
return -ENODEV;
@@ -2263,6 +2234,9 @@
if (retval)
goto dput_out;
+ if (!may_mount())
+ return -EPERM;
+
/* Default to relatime unless overriden */
if (!(flags & MS_NOATIME))
mnt_flags |= MNT_RELATIME;