Re: [PATCH v5 net-next 0/4] rtnetlink: improve ALT_IFNAME config and fix dangerous GROUP usage

["Jason A. Donenfeld" <Jason@zx2c4.com>]

Hi Florent,

On Fri, Apr 15, 2022 at 06:53:26PM +0200, Florent Fourcot wrote:
> First commit forbids dangerous calls when both IFNAME and GROUP are
> given, since it can introduce unexpected behaviour when IFNAME does not
> match any interface.
> 
> Second patch achieves primary goal of this patchset to fix/improve
> IFLA_ALT_IFNAME attribute, since previous code was never working for
> newlink/setlink. ip-link command is probably getting interface index
> before, and was not using this feature.
> 
> Last two patches are improving error code on corner cases.

This was just merged to net-next and appears to have broken the
wireguard test suite over on https://build.wireguard.com/

[+] Launching tests...
[    0.796066] init.sh (28) used greatest stack depth: 29152 bytes left
[    0.803809] ip (29) used greatest stack depth: 28544 bytes left
[+] ip netns add wg-test-27-0
[+] ip netns add wg-test-27-1
[    0.842841] ip (32) used greatest stack depth: 27512 bytes left
[+] ip netns add wg-test-27-2
[+] NS0: ip link set up dev lo
[+] NS0: ip link add dev wg0 type wireguard
[    0.896074] ip (35) used greatest stack depth: 27152 bytes left
Command "add" is unknown, try "ip link help".
[+] NS0: ip link del dev wg0
[+] NS0: ip link del dev wg1
[+] NS1: ip link del dev wg0
[+] NS1: ip link del dev wg1
[+] NS2: ip link del dev wg0
[+] NS2: ip link del dev wg1
[+] ip netns del wg-test-27-1
[+] ip netns del wg-test-27-2
[+] ip netns del wg-test-27-0
[-] Tests failed with exit code 255! ☹

So apparently something goes wrong with "ip link add dev wg0 type
wireguard". Not quite sure what yet, though. You can try it for yourself
with:

    make -C tools/testing/selftests/wireguard/qemu -j$(nproc)

Jason