Messages in this thread Patch in this message | | | From | Eric Dumazet <> | Date | Wed, 22 Jun 2022 21:27:11 +0200 | Subject | Re: [PATCH net] net: ensure all external references are released in deferred skbuffs |
| |
On Wed, Jun 22, 2022 at 9:04 PM Eric Dumazet <edumazet@google.com> wrote: > > On Wed, Jun 22, 2022 at 8:19 PM Ilya Maximets <i.maximets@ovn.org> wrote: > > > > On 6/22/22 19:03, Eric Dumazet wrote: > > > On Wed, Jun 22, 2022 at 6:47 PM Eric Dumazet <edumazet@google.com> wrote: > > >> > > >> On Wed, Jun 22, 2022 at 6:39 PM Eric Dumazet <edumazet@google.com> wrote: > > >>> > > >>> On Wed, Jun 22, 2022 at 6:29 PM Eric Dumazet <edumazet@google.com> wrote: > > >>>> > > >>>> On Wed, Jun 22, 2022 at 4:26 PM Ilya Maximets <i.maximets@ovn.org> wrote: > > >>>>> > > >>>>> On 6/22/22 13:43, Eric Dumazet wrote: > > >>>> > > >>>>> > > >>>>> I tested the patch below and it seems to fix the issue seen > > >>>>> with OVS testsuite. Though it's not obvious for me why this > > >>>>> happens. Can you explain a bit more? > > >>>> > > >>>> Anyway, I am not sure we can call nf_reset_ct(skb) that early. > > >>>> > > >>>> git log seems to say that xfrm check needs to be done before > > >>>> nf_reset_ct(skb), I have no idea why. > > >>> > > >>> Additional remark: In IPv6 side, xfrm6_policy_check() _is_ called > > >>> after nf_reset_ct(skb) > > >>> > > >>> Steffen, do you have some comments ? > > >>> > > >>> Some context: > > >>> commit b59c270104f03960069596722fea70340579244d > > >>> Author: Patrick McHardy <kaber@trash.net> > > >>> Date: Fri Jan 6 23:06:10 2006 -0800 > > >>> > > >>> [NETFILTER]: Keep conntrack reference until IPsec policy checks are done > > >>> > > >>> Keep the conntrack reference until policy checks have been performed for > > >>> IPsec NAT support. The reference needs to be dropped before a packet is > > >>> queued to avoid having the conntrack module unloadable. > > >>> > > >>> Signed-off-by: Patrick McHardy <kaber@trash.net> > > >>> Signed-off-by: David S. Miller <davem@davemloft.net> > > >>> > > >> > > >> Oh well... __xfrm_policy_check() has : > > >> > > >> nf_nat_decode_session(skb, &fl, family); > > >> > > >> This answers my questions. > > >> > > >> This means we are probably missing at least one XFRM check in TCP > > >> stack in some cases. > > >> (Only after adding this XFRM check we can call nf_reset_ct(skb)) > > >> > > > > > > Maybe this will help ? > > > > I tested this patch and it seems to fix the OVS problem. > > I did not test the xfrm part of it. > > > > Will you post an official patch? > > Yes I will. I need to double check we do not leak either the req, or the child. > > Maybe the XFRM check should be done even earlier, on the listening socket ? > > Or if we assume the SYNACK packet has been sent after the XFRM test > has been applied to the SYN, > maybe we could just call nf_reset_ct(skb) to lower risk of regressions. > > With the last patch, it would be strange that we accept the 3WHS and > establish a socket, > but drop the payload in the 3rd packet...
Ilya, can you test the following patch ? I think it makes more sense to let XFRM reject the packet earlier, and not complete the 3WHS, if for some reason this happens.
Thanks !
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index fe8f23b95d32ca4a35d05166d471327bc608fa91..da5a3c44c4fb70f1d3ecc596e694a86267f1c44a 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -1964,7 +1964,10 @@ int tcp_v4_rcv(struct sk_buff *skb) struct sock *nsk;
sk = req->rsk_listener; - drop_reason = tcp_inbound_md5_hash(sk, skb, + if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb)) + drop_reason = SKB_DROP_REASON_XFRM_POLICY; + else + drop_reason = tcp_inbound_md5_hash(sk, skb, &iph->saddr, &iph->daddr, AF_INET, dif, sdif); if (unlikely(drop_reason)) { @@ -2016,6 +2019,7 @@ int tcp_v4_rcv(struct sk_buff *skb) } goto discard_and_relse; } + nf_reset_ct(skb); if (nsk == sk) { reqsk_put(req); tcp_v4_restore_cb(skb);
| |