On Mon, Mar 21, 2022 at 10:44:39AM +0100, Pablo Neira Ayuso wrote:
> On Mon, Mar 21, 2022 at 10:42:05AM +0100, Pablo Neira Ayuso wrote:
> > When tcp_options is called all flags are cleared.
> > When the IP_CT_TCP_FLAG_BE_LIBERAL is set it should be preserved
> > otherwise such connections will fail in the window check.
>
>
> This patch completes 8437a6209f76 ("netfilter: nft_flow_offload: set liberal tracking mode for tcp")
>
> I'm going to send v2 to add a wrapper function to update these flags,
> so we do not accidentally reset IP_CT_TCP_FLAG_BE_LIBERAL.
Hm. Actually I don't see a clear way to add such wrapper function, so
patch LGTM as is.
> > Signed-off-by: Sven Auhagen <sven.auhagen@xxxxxxxxxxxx>
> > Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
> > ---
> > Supersedes: https://patchwork.ozlabs.org/project/netfilter-devel/patch/20220318144939.69465-1-pablo@xxxxxxxxxxxxx/ which is not correct, it breaks TCP FIN handling.
> >
> > net/netfilter/nf_conntrack_proto_tcp.c | 6 ++++--
> > 1 file changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/net/netfilter/nf_conntrack_proto_tcp.c b/net/netfilter/nf_conntrack_proto_tcp.c
> > index d1582b888c0d..d8599ab5f767 100644
> > --- a/net/netfilter/nf_conntrack_proto_tcp.c
> > +++ b/net/netfilter/nf_conntrack_proto_tcp.c
> > @@ -342,7 +342,7 @@ static void tcp_options(const struct sk_buff *skb,
> > return;
> >
> > state->td_scale =
> > - state->flags = 0;
> > + state->flags &= IP_CT_TCP_FLAG_BE_LIBERAL;
> >
> > while (length > 0) {
> > int opcode=*ptr++;
> > @@ -873,7 +873,7 @@ int nf_conntrack_tcp_packet(struct nf_conn *ct,
> > struct nf_tcp_net *tn = nf_tcp_pernet(net);
> > struct nf_conntrack_tuple *tuple;
> > enum tcp_conntrack new_state, old_state;
> > - unsigned int index, *timeouts;
> > + unsigned int index, flags, *timeouts;
> > enum ip_conntrack_dir dir;
> > const struct tcphdr *th;
> > struct tcphdr _tcph;
> > @@ -968,8 +968,10 @@ int nf_conntrack_tcp_packet(struct nf_conn *ct,
> > ct->proto.tcp.last_flags &= ~IP_CT_EXP_CHALLENGE_ACK;
> > ct->proto.tcp.seen[ct->proto.tcp.last_dir].flags =
> > ct->proto.tcp.last_flags;
> > + flags = ct->proto.tcp.seen[dir].flags;
> > memset(&ct->proto.tcp.seen[dir], 0,
> > sizeof(struct ip_ct_tcp_state));
> > + ct->proto.tcp.seen[dir].flags = flags & IP_CT_TCP_FLAG_BE_LIBERAL;
> > break;
> > }
> > ct->proto.tcp.last_index = index;
> > --
> > 2.30.2
> >
