12:40 p.m.
Hello all,
When I upgraded podman from 2.1.1 to 2.2.1, my wireguard container stopped
working because wg-quick returned a 'permission denied' error. After some
bug hunting, I found out that starting a (rootful) container like this...
podman run --rm --uidmap 0:60000:1000 --gidmap 0:60000:1000 \
docker.io/library/alpine:3.12 \
grep ^Cap /proc/self/status
...on podman 2.1.1 returns a capability mask of a80425fb for all of CapInh,
CapPrm, CapEff, CapBnd and CapAmb, and on podman 2.2.1 returns 800405fb for all
of the capability masks except for CapAmb, which is all zeroes.
So on podman 2.1.1 my rootful usernamespaced container ran with these capabilities:
0x00000000a80425fb=cap_chown,cap_dac_override,cap_fowner,cap_fsetid,cap_kill,cap_setgid,cap_setuid,cap_setpcap,cap_net_bind_service,cap_net_raw,cap_sys_chroot,cap_mknod,cap_audit_write,cap_setfcap
And on podman 2.2.1 with these:
0x00000000800405fb=cap_chown,cap_dac_override,cap_fowner,cap_fsetid,cap_kill,cap_setgid,cap_setuid,cap_setpcap,cap_net_bind_service,cap_sys_chroot,cap_setfcap
So, containers no longer run with CAP_NET_RAW, CAP_MKNOD and CAP_AUDIT_WRITE,
which for for my wireguard container means I now have to `--cap-add`
CAP_NET_RAW in addition to CAP_NET_ADMIN, because `wg-quick` runs `iptables`,
which opens some raw sockets to communicate with the kernel.
I wonder what is the background of this change, is it intentional? And I also
noticed CapAmb is now all zeroes, which seems to have to do with commit bce8f8
[1], but reading the code I don't understand why CapAmb is now empty when it
seems to be the intention to populate it.
Regards,
Joost Molenaar
[1] https://github.com/containers/podman/commit/bce8f851c1e891aa6159e61c56ccd...