On 4/16/25 15:42, Gabriel Totev wrote:
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.
so unfortunately this isn't correct. Yes some mapping needs to be
done but it needs to be relative to different policy namespaces. I
need to spend some time on this
Signed-off-by: Gabriel Totev <[email protected]>
---
security/apparmor/file.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/security/apparmor/file.c b/security/apparmor/file.c
index 5c984792cbf0..ecd36199337c 100644
--- a/security/apparmor/file.c
+++ b/security/apparmor/file.c
@@ -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;
