[PATCH net v2] ipv6: socket SO_BINDTODEVICE lookup routing fail without IPv6 rule.

[Jakub Kicinski]

On Fri, 3 Jan 2025 13:43:49 +0800 Shiming Cheng wrote:
> When using socket IPv6 with SO_BINDTODEVICE, if IPv6 rule is not
> matched, it will return ENETUNREACH. In fact, IPv4 does not behave
> this way. IPv4 prioritizes looking up IP rules for routing and
> forwarding, if not matched it will use socket-bound out interface
> to send packets. The modification here is to make IPv6 behave the
> same as IPv4. If IP rule is not found, it will also use socket-bound
> out interface to send packts.

CI shows failures in tools/testing/selftests/net/fcnal-test.sh
and tools/testing/selftests/net/fib_nexthops.sh with this patch
applied. Could be a flake but please double check before sending v3