From: Pablo Neira Ayuso pablo@netfilter.org
[ Upstream commit f2dd495a8d589371289981d5ed33e6873df94ecc ]
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@voleatech.de Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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;