[pkg-go] Bug#1118056: podman: `podman network create` refuses network range if in use by the host

[Jonathan Dowland]

Package: podman
Version: 5.4.2+ds1-2+b1
Severity: normal

Dear Maintainer,

Prior to Trixie/5.4.2, I had Podman bridged network defined as a subset 
of the IP range of my local physical network. This was configured via 
the CNI backend (following [1], my write-up was [2]). With the upgrade 
to Trixie, my CNI-backed network definitions were removed and my 
containers would not start.

In repairing this, I discovered that 5.4.2 (with the Netavark backend) 
detects and prevents you configuring a Podman network that uses a subnet 
already available on the host. Assuming local network 192.168.1.0/24:

  $ podman network create --opt mode=unmanaged --interface-name=br0 --subnet 192.168.1.0/24 podbr0
  Error: subnet 192.168.1.0/24 is already used on the host or by another config

A workaround is to define it with a temporary subnet and then edit the 
JSON in /etc/containers/networks afterwards.

This has been fixed by 5.6.2 (sid's package).

I'm reporting it because I think it's useful to record the versions that 
are broken/fixed (I haven't found this reported upstream yet) but also 
because I would like to suggest backporting a fix (once 
identified/isolated) should be considered.


[1] https://blog.carroarmato0.be/2020/05/08/exposing-podman-container-on-the-network/
[2] https://jmtd.net/log/podman_network/

-- System Information:
Debian Release: 13.0
  APT prefers stable
  APT policy: (990, 'stable'), (500, 'stable-updates'), (500, 'stable-security'), (500, 'unstable')
Architecture: amd64 (x86_64)
Foreign Architectures: i386, ppc64el

Kernel: Linux 6.12.38+deb13-amd64 (SMP w/12 CPU threads; PREEMPT)
Kernel taint flags: TAINT_WARN
Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8), LANGUAGE=en_GB:en
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages podman depends on:
ii  conmon                           2.1.12-4
ii  golang-github-containers-common  0.62.2+ds1-2
ii  init-system-helpers              1.68
ii  libc6                            2.41-12
ii  libgpgme11t64                    1.24.2-3
ii  libseccomp2                      2.6.0-2
ii  libsqlite3-0                     3.46.1-7
ii  libsubid5                        1:4.17.4-2
ii  netavark                         1.14.0-2
ii  runc                             1.1.15+ds1-2+b4

Versions of packages podman recommends:
ii  buildah             1.39.3+ds1-1+b6
ii  ca-certificates     20250419
ii  containers-storage  1.57.2+ds1-1+b2
ii  criu                4.1.1-1
ii  dbus-user-session   1.16.2-2
ii  libcriu2            4.1.1-1
ii  passt               0.0~git20250503.587980c-2
ii  slirp4netns         1.2.1-1.1
ii  tini                0.19.0-3+b3
ii  uidmap              1:4.17.4-2

Versions of packages podman suggests:
ii  containernetworking-plugins  1.1.1+ds1-3+b17
ii  docker-compose               2.26.1-4
ii  iptables                     1.8.11-2

-- Configuration Files:
/etc/cni/net.d/87-podman-bridge.conflist [Errno 13] Permission denied: '/etc/cni/net.d/87-podman-bridge.conflist'

-- no debconf information