diff options
Diffstat (limited to 'net/netfilter')
| -rw-r--r-- | net/netfilter/nf_conntrack_proto_tcp.c | 50 |
1 files changed, 40 insertions, 10 deletions
diff --git a/net/netfilter/nf_conntrack_proto_tcp.c b/net/netfilter/nf_conntrack_proto_tcp.c index 01c748fa8913..a06875a466a4 100644 --- a/net/netfilter/nf_conntrack_proto_tcp.c +++ b/net/netfilter/nf_conntrack_proto_tcp.c @@ -828,6 +828,12 @@ static noinline bool tcp_new(struct nf_conn *ct, const struct sk_buff *skb, return true; } +static bool nf_conntrack_tcp_established(const struct nf_conn *ct) +{ + return ct->proto.tcp.state == TCP_CONNTRACK_ESTABLISHED && + test_bit(IPS_ASSURED_BIT, &ct->status); +} + /* Returns verdict for packet, or -1 for invalid. */ int nf_conntrack_tcp_packet(struct nf_conn *ct, struct sk_buff *skb, @@ -1030,16 +1036,38 @@ int nf_conntrack_tcp_packet(struct nf_conn *ct, new_state = TCP_CONNTRACK_ESTABLISHED; break; case TCP_CONNTRACK_CLOSE: - if (index == TCP_RST_SET - && (ct->proto.tcp.seen[!dir].flags & IP_CT_TCP_FLAG_MAXACK_SET) - && before(ntohl(th->seq), ct->proto.tcp.seen[!dir].td_maxack)) { - /* Invalid RST */ - spin_unlock_bh(&ct->lock); - nf_ct_l4proto_log_invalid(skb, ct, "invalid rst"); - return -NF_ACCEPT; + if (index != TCP_RST_SET) + break; + + if (ct->proto.tcp.seen[!dir].flags & IP_CT_TCP_FLAG_MAXACK_SET) { + u32 seq = ntohl(th->seq); + + if (before(seq, ct->proto.tcp.seen[!dir].td_maxack)) { + /* Invalid RST */ + spin_unlock_bh(&ct->lock); + nf_ct_l4proto_log_invalid(skb, ct, "invalid rst"); + return -NF_ACCEPT; + } + + if (!nf_conntrack_tcp_established(ct) || + seq == ct->proto.tcp.seen[!dir].td_maxack) + break; + + /* Check if rst is part of train, such as + * foo:80 > bar:4379: P, 235946583:235946602(19) ack 42 + * foo:80 > bar:4379: R, 235946602:235946602(0) ack 42 + */ + if (ct->proto.tcp.last_index == TCP_ACK_SET && + ct->proto.tcp.last_dir == dir && + seq == ct->proto.tcp.last_end) + break; + + /* ... RST sequence number doesn't match exactly, keep + * established state to allow a possible challenge ACK. + */ + new_state = old_state; } - if (index == TCP_RST_SET - && ((test_bit(IPS_SEEN_REPLY_BIT, &ct->status) + if (((test_bit(IPS_SEEN_REPLY_BIT, &ct->status) && ct->proto.tcp.last_index == TCP_SYN_SET) || (!test_bit(IPS_ASSURED_BIT, &ct->status) && ct->proto.tcp.last_index == TCP_ACK_SET)) @@ -1055,7 +1083,7 @@ int nf_conntrack_tcp_packet(struct nf_conn *ct, * segments we ignored. */ goto in_window; } - /* Just fall through */ + break; default: /* Keep compilers happy. */ break; @@ -1090,6 +1118,8 @@ int nf_conntrack_tcp_packet(struct nf_conn *ct, if (ct->proto.tcp.retrans >= tn->tcp_max_retrans && timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS]) timeout = timeouts[TCP_CONNTRACK_RETRANS]; + else if (unlikely(index == TCP_RST_SET)) + timeout = timeouts[TCP_CONNTRACK_CLOSE]; else if ((ct->proto.tcp.seen[0].flags | ct->proto.tcp.seen[1].flags) & IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED && timeouts[new_state] > timeouts[TCP_CONNTRACK_UNACK]) |