Messages in this thread | | | Subject | Re: [PATCH] tcp: md5: Fix overlap between vrf and non-vrf keys | From | Leonard Crestez <> | Date | Fri, 8 Oct 2021 18:51:56 +0300 |
| |
On 07.10.2021 21:27, David Ahern wrote: > On 10/7/21 12:41 AM, Leonard Crestez wrote: >> On 07.10.2021 04:14, David Ahern wrote: >>> On 10/6/21 11:48 AM, Leonard Crestez wrote: >>>> @@ -1103,11 +1116,11 @@ static struct tcp_md5sig_key >>>> *tcp_md5_do_lookup_exact(const struct sock *sk, >>>> #endif >>>> hlist_for_each_entry_rcu(key, &md5sig->head, node, >>>> lockdep_sock_is_held(sk)) { >>>> if (key->family != family) >>>> continue; >>>> - if (key->l3index && key->l3index != l3index) >>>> + if (key->l3index != l3index) >>> >>> That seems like the bug fix there. The L3 reference needs to match for >>> new key and existing key. I think the same change is needed in >>> __tcp_md5_do_lookup. >> >> Current behavior is that keys added without tcpm_ifindex will match >> connections both inside and outside VRFs. Changing this might break real >> applications, is it really OK to claim that this behavior was a bug all >> along? > > no. > > It's been a few years. I need to refresh on the logic and that is not > going to happen before this weekend.
It seems that always doing a strict key->l3index != l3index condition inside of __tcp_md5_do_lookup breaks the usecase of binding one listener to each VRF and not specifying the ifindex for each key.
This is a very valid usecase, maybe the most common way to use md5 with vrf.
Ways to fix this: * Make this comparison only take effect if TCP_MD5SIG_FLAG_IFINDEX is set. * Make this comparison only take effect if tcp_l3mdev_accept=1 * Add a new flag?
Right now passing TCP_MD5SIG_FLAG_IFINDEX and ifindex == 0 results in an error but maybe it should be accepted to mean "key applies only for default VRF".
-- Regards, Leonard
| |