ovl: handle idmapped mounts in ovl_set_acl()

Browse source

The two checks ovl_set_acl() performs on the overlay inode itself -
inode_owner_or_capable() and the setgid-stripping test - were done with
&nop_mnt_idmap.  On an idmapped overlay mount this compares the overlay
inode's id space directly against the caller's: it denies the rightful
owner (as seen through the mount idmap) the right to set an ACL, and
evaluates the setgid-drop decision in the wrong id space, which can
mis-set the mode on the upper inode.

Use the struct mnt_idmap passed in by the VFS for both.  Fold the
open-coded "caller not in group and not CAP_FSETID privileged" test
into in_group_or_capable() with i_gid_into_vfsgid(), the same
idmap-aware helpers used by setattr_should_drop_sgid().

The subsequent internal forced setgid-kill via ovl_setattr() stays on
&nop_mnt_idmap: it carries only ATTR_KILL_SGID with no uid/gid to
translate and is overlayfs' own mode change, not a user-driven
operation through the mount.

No functional change until FS_ALLOW_IDMAP is set on ovl_fs_type.

Link: https://patch.msgid.link/20260615-work-idmapped-overlayfs-v1-5-7381632aa402@kernel.org
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>

...

This commit is contained in:

Christian Brauner 2026-06-15 15:19:54 +02:00

parent 22b27d403d

commit d1f78a3fed

No known key found for this signature in database

GPG key ID: 91C61BC06578DCA2

1 changed files with 3 additions and 3 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

6

fs/overlayfs/inode.c

View file