On 6/6/19 2:13 PM, Stefano Brivio wrote:
> Since commit 2b760fcf5cfb ("ipv6: hook up exception table to store dst
> cache"), route exceptions reside in a separate hash table, and won't be
> found by walking the FIB, so they won't be dumped to userspace on a
> RTM_GETROUTE message.
>
> This causes 'ip -6 route list cache' and 'ip -6 route flush cache' to
> have no function anymore:
>
> # ip -6 route get fc00:3::1
> fc00:3::1 via fc00:1::2 dev veth_A-R1 src fc00:1::1 metric 1024 expires
> 539sec mtu 1400 pref medium
> # ip -6 route get fc00:4::1
> fc00:4::1 via fc00:2::2 dev veth_A-R2 src fc00:2::1 metric 1024 expires
> 536sec mtu 1500 pref medium
> # ip -6 route list cache
> # ip -6 route flush cache
> # ip -6 route get fc00:3::1
> fc00:3::1 via fc00:1::2 dev veth_A-R1 src fc00:1::1 metric 1024 expires
> 520sec mtu 1400 pref medium
> # ip -6 route get fc00:4::1
> fc00:4::1 via fc00:2::2 dev veth_A-R2 src fc00:2::1 metric 1024 expires
> 519sec mtu 1500 pref medium
>
> because iproute2 lists cached routes using RTM_GETROUTE, and flushes them
> by listing all the routes, and deleting them with RTM_DELROUTE one by one.
>
> Look up exceptions in the hash table associated with the current fib6_info
> in rt6_dump_route(), and, if present and not expired, add them to the
> dump.
>
> Re-allow userspace to get FIB results by passing the RTM_F_CLONED flag as
> filter, by reverting commit 08e814c9e8eb ("net/ipv6: Bail early if user
> only wants cloned entries").
>
> As we do this, we also have to honour this flag while filtering routes in
> rt6_dump_route() and, if this filter effectively causes some results to be
> discarded, by passing the NLM_F_DUMP_FILTERED flag back.
>
> To flush cached routes, a procfs entry could be introduced instead: that's
> how it works for IPv4. We already have a rt6_flush_exception() function
> ready to be wired to it. However, this would not solve the issue for
> listing, and wouldn't fix the issue with current and previous versions of
> iproute2.
>
> Reported-by: Jianlin Shi <[email protected]>
> Fixes: 2b760fcf5cfb ("ipv6: hook up exception table to store dst cache")
> Signed-off-by: Stefano Brivio <[email protected]>
> ---
> This will cause a non-trivial conflict with commit cc5c073a693f
> ("ipv6: Move exception bucket to fib6_nh") on net-next. I can submit
> an equivalent patch against net-next, if it helps.
>
Thanks for doing this. It is on my to-do list.
Can you do the same for IPv4?
