Do not reset IP_CT_TCP_FLAG_BE_LIBERAL flag in out-of-sync scenarios
coming before the TCP window tracking, otherwise such connections will
fail in the window check.
Update tcp_options() to leave this flag in place and add a new helper
function to reset the tcp window state.
Based on patch from Sven Auhagen.
Fixes: c4832c7bbc3f ("netfilter: nf_ct_tcp: improve out-of-sync situation in TCP tracking")
Tested-by: Sven Auhagen <sven.auhagen@xxxxxxxxxxxx>
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
---
net/netfilter/nf_conntrack_proto_tcp.c | 17 +++++++++++++----
1 file changed, 13 insertions(+), 4 deletions(-)
diff --git a/net/netfilter/nf_conntrack_proto_tcp.c b/net/netfilter/nf_conntrack_proto_tcp.c
index d1582b888c0d..8ec55cd72572 100644
--- a/net/netfilter/nf_conntrack_proto_tcp.c
+++ b/net/netfilter/nf_conntrack_proto_tcp.c
@@ -341,8 +341,8 @@ static void tcp_options(const struct sk_buff *skb,
if (!ptr)
return;
- state->td_scale =
- state->flags = 0;
+ state->td_scale = 0;
+ state->flags &= IP_CT_TCP_FLAG_BE_LIBERAL;
while (length > 0) {
int opcode=*ptr++;
@@ -862,6 +862,16 @@ static bool tcp_can_early_drop(const struct nf_conn *ct)
return false;
}
+static void nf_ct_tcp_state_reset(struct ip_ct_tcp_state *state)
+{
+ state->td_end = 0;
+ state->td_maxend = 0;
+ state->td_maxwin = 0;
+ state->td_maxack = 0;
+ state->td_scale = 0;
+ state->flags &= IP_CT_TCP_FLAG_BE_LIBERAL;
+}
+
/* Returns verdict for packet, or -1 for invalid. */
int nf_conntrack_tcp_packet(struct nf_conn *ct,
struct sk_buff *skb,
@@ -968,8 +978,7 @@ 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;
- memset(&ct->proto.tcp.seen[dir], 0,
- sizeof(struct ip_ct_tcp_state));
+ nf_ct_tcp_state_reset(&ct->proto.tcp.seen[dir]);
break;
}
ct->proto.tcp.last_index = index;
--
2.30.2
