podman/slirp4netns: `open("/dev/net/tun"): No such file or directory`

With podman - 5.2.2-r1 on OpenWrt 24.10.0-rc5 r28304-6dacba30a7 installed, running

podman run --rm --network=host docker.io/library/busybox ip a

works fine.

Seeing podman package pulls in slirp4netns via

# opkg info podman | grep '^Depends:'
Depends: libc, conmon, libgpgme, libseccomp, nsenter, zoneinfo-simple, kmod-veth, slirp4netns, netavark, aardvark-dns, catatonit, crun

I then tried to use a more isolated network setup:

# podman run --rm --network=slirp4netns docker.io/library/busybox ip a
Error: /usr/bin/slirp4netns failed: "WARNING: Support for seccomp is experimental\nopen(\"/dev/net/tun\"): No such file or directory\nWARNING: Support for IPv6 is experimental\nchild failed(1)\nWARNING: Support for IPv6 is experimental\n"

The issue gets fixed by manually installing the tun kernel module:

# opkg install kmod-tun
Installing kmod-tun (6.6.69-r1) to root...
Downloading https://downloads.openwrt.org/releases/24.10.0-rc5/targets/mediatek/filogic/kmods/6.6.69-1-83c6d4e14f7353564d3cadaf38a15bef/kmod-tun_6.6.69-r1_aarch64_cortex-a53.ipk
Configuring kmod-tun.

But if slirp4netns needs that module for its basic operation, it should likely include the kmod-tun package as a dependency.

Start by locating the OpenWrt package definition for slirp4netns and reviewing how package dependencies are declared. Reproduce the failure with the shown podman command, then verify that installing the package also provides kmod-tun and that slirp4netns networking works without a separate module install.