This bug is missing log files that will aid in diagnosing the problem.
While running an Ubuntu kernel (not a mainline or third-party kernel)
please enter the following command in a terminal window:
apport-collect 1998602
and then change the status of the bug to 'Confirmed'.
If, due to the nature of the issue you have encountered, you are unable
to run this command, please add a comment stating that fact and change
the bug status to 'Confirmed'.
This change has been made by an automated script, maintained by the
Ubuntu Kernel Team.
** Changed in: linux (Ubuntu)
Status: New => Incomplete
--
You received this bug notification because you are a member of Kernel
Packages, which is subscribed to linux in Ubuntu.
https://bugs.launchpad.net/bugs/1998602
Title:
overlay writing user.* xattrs on symlinks
Status in linux package in Ubuntu:
Incomplete
Bug description:
This was reported (and worked around) in https://github.com/project-
stacker/stacker/pull/333.
The kernel does not allow user.* xattrs on a symlink. However, on
5.15.0-53-generic and 5.19.0-21-generic, but not on the ubuntu
mainline build (6.1.0-060100rc5-generic), an unprivileged program can
cause such xattrs to be created. Once they're there, userspace (i.e.
setfattr) cannot remove them since the kernel says they can't exist -
but listxattr shows them.
I've failed so far in setting up a simpler reproducer, so I'll begin
by reporting the full reproducer. Download 'stacker' from
https://github.com/project-
stacker/stacker/releases/download/v0.22.1/stacker . Create a
stacker.yaml config file:
cat > stacker.yaml << EOF
pxe-server-base:
from:
type: docker
url: docker://ubuntu:jammy
run: |
apt-get update
apt-get -y install dnsmasq systemd
sb-pxe-server:
from:
type: built
tag: pxe-server-base
run: |
systemctl disable dnsmasq
EOF
and run 'stacker build'. It will end with:
Executing: /lib/systemd/systemd-sysv-install disable dnsmasq
Removed /etc/systemd/system/multi-user.target.wants/dnsmasq.service.
error: /home/ubuntu/build2/roots/sb-pxe-server/overlay/etc/rc2.d/K01dnsmasq:
failed to remove attr user.overlay.origin: xattr.LRemove
/home/ubuntu/build2/roots/sb-pxe-server/overlay/etc/rc2.d/K01dnsmasq
user.overlay.origin: operation not permitted
error: exit status 1
You'll subsequently see that ./roots/sb-pxe-
server/overlay/etc/rc2.d/K01dnsmasq is a symbolic link with
user.overlay.origin xattr (per llistxatr), though you can't read the
contents or delete it.
I had thought I should be able to reproduce it by mounting (in an
unprivileged user+mountns) an overlayfs where the underlay has, say,
"/etc/rc2.d/K" symlink, then rename K to S (as i assume the 'systemctl
disable dnsmasq is doing), but that did not work for me.
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1998602/+subscriptions
--
Mailing list: https://launchpad.net/~kernel-packages
Post to : [email protected]
Unsubscribe : https://launchpad.net/~kernel-packages
More help : https://help.launchpad.net/ListHelp
