Debian 12.1 (6.1.0-11-amd64) running LXD/LXC and on an unprivileged container setting security.idmap.isolated=true seems to fail to update the owner/group of the container's files.
Here is an example:
# lxc launch images:debian/12 debian
(...)
# lxc config get debian volatile.idmap.base
296608
# lxc stop debian
Error: The instance is already stopped
# lxc config set debian security.idmap.isolated true
# lxc config get debian security.idmap.isolated
true
# lxc start debian
Now if I list the files on the container volume I'll get they're all owned by the host root user:
# ls -la /mnt/NVME1/lxd/containers/debian/rootfs/
total 24
drwxr-xr-x 1 root root 154 Sep 5 06:28 .
d--x------ 1 296608 root 78 Sep 5 15:59 ..
lrwxrwxrwx 1 root root 7 Sep 5 06:25 bin -> usr/bin
drwxr-xr-x 1 root root 0 Jul 14 17:00 boot
drwxr-xr-x 1 root root 0 Sep 5 06:28 dev
drwxr-xr-x 1 root root 1570 Sep 5 06:28 etc
I tried multiple versions of LXD/LXC. This happens with both 5.0.2 from apt as well with 4.0 and 5.17 (latest) from snap.
Interestingly enough I have another Debian 10 (4.19.0-25-amd64) running and older LXD 4 from snap and on that one things work as expected:
# ls -la /mnt/NVME1/lxd/containers/debian/rootfs/
total 0
drwxr-xr-x 1 1065536 1065536 138 Oct 29 2020 .
d--x------ 1 1065536 root 78 Oct 14 2020 ..
drwxr-xr-x 1 1065536 1065536 1328 Jul 24 19:07 bin
drwxr-xr-x 1 1065536 1065536 0 Sep 19 2020 boot
drwxr-xr-x 1 1065536 1065536 0 Oct 14 2020 dev
drwxr-xr-x 1 1065536 1065536 1716 Jul 24 19:08 etc
As you can see on this systems all the files are owned by 1065536:1065536.
Update:
I tried to probe around the maps with lxc config show debian in both machines and I saw this:
Machine running Debian 10:
security.idmap.isolated: "true"
(...)
volatile.idmap.base: "1065536"
volatile.idmap.current: '[{"Isuid":true,"Isgid":false,"Hostid":1065536,"Nsid":0,"Maprange":65536},{"Isuid":false,"Isgid":true,"Hostid":1065536,"Nsid":0,"Maprange":65536}]'
volatile.idmap.next: '[{"Isuid":true,"Isgid":false,"Hostid":1065536,"Nsid":0,"Maprange":65536},{"Isuid":false,"Isgid":true,"Hostid":1065536,"Nsid":0,"Maprange":65536}]'
volatile.last_state.idmap: '[{"Isuid":true,"Isgid":false,"Hostid":1065536,"Nsid":0,"Maprange":65536},{"Isuid":false,"Isgid":true,"Hostid":1065536,"Nsid":0,"Maprange":65536}]'
Machine running Debian 12:
security.idmap.isolated: "true"
(...)
volatile.idmap.base: "231072"
volatile.idmap.current: '[{"Isuid":true,"Isgid":false,"Hostid":231072,"Nsid":0,"Maprange":65536},{"Isuid":false,"Isgid":true,"Hostid":231072,"Nsid":0,"Maprange":65536}]'
volatile.idmap.next: '[{"Isuid":true,"Isgid":false,"Hostid":231072,"Nsid":0,"Maprange":65536},{"Isuid":false,"Isgid":true,"Hostid":231072,"Nsid":0,"Maprange":65536}]'
volatile.last_state.idmap: '[]'
Why didn't it populate volatile.last_state.idmap: '[]'?
How can I fix it? Thank you.
Just be aware of the risks involved with running your own CA.
You’re adding a root certificate to your systems that will effectively accept any certificate issued with your CA’s key. If your PK gets stolen somehow and you don’t notice it, someone might be issuing certificates that are valid for those machines. Also real CA’s also have ways to revoke certificates that are checked by browsers (OCSP and CRLs), they may employ other techniques such as cross signing and chains of trust. All those make it so a compromised certificate is revoked and not trusted by anyone after the fact.
For what's worth, LetsEncrypt with DNS-01 challenge is way easier to deploy and maintain in your internal hosts than adding a CA and dealing with all the devices that might not like custom CAs. Also more secure.