mirrors/linux
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git synced 2025-12-27 12:21:22 -05:00
Code Issues Packages Projects Releases Wiki Activity

apparmor: shift ouid when mediating hard links in userns

Browse Source 
When using AppArmor profiles inside an unprivileged container,
the link operation observes an unshifted ouid.
(tested with LXD and Incus)

For example, root inside container and uid 1000000 outside, with
`owner /root/link l,` profile entry for ln:

/root$ touch chain && ln chain link
==> dmesg
apparmor="DENIED" operation="link" class="file"
namespace="root//lxd-feet_<var-snap-lxd-common-lxd>" profile="linkit"
name="/root/link" pid=1655 comm="ln" requested_mask="l" denied_mask="l"
fsuid=1000000 ouid=0 [<== should be 1000000] target="/root/chain"

Fix by mapping inode uid of old_dentry in aa_path_link() rather than
using it directly, similarly to how it's mapped in __file_path_perm()
later in the file.

Signed-off-by: Gabriel Totev <gabriel.totev@zetier.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>
This commit is contained in:
Gabriel Totev
2025-04-16 18:42:08 -04:00
committed by John Johansen
parent 88fec3526e
commit c5bf96d20f
1 changed files with 4 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
security/apparmor/file.c
View File

@@ -430,9 +430,11 @@ int aa_path_link(const struct cred *subj_cred,
{
struct path link = { .mnt = new_dir->mnt, .dentry = new_dentry };
struct path target = { .mnt = new_dir->mnt, .dentry = old_dentry };
struct inode *inode = d_backing_inode(old_dentry);
vfsuid_t vfsuid = i_uid_into_vfsuid(mnt_idmap(target.mnt), inode);
struct path_cond cond = {
d_backing_inode(old_dentry)->i_uid,
d_backing_inode(old_dentry)->i_mode
.uid = vfsuid_into_kuid(vfsuid),
.mode = inode->i_mode,
};
char *buffer = NULL, *buffer2 = NULL;
struct aa_profile *profile;