diff options
author | Pablo Neira Ayuso | 2012-06-07 13:31:25 +0200 |
---|---|---|
committer | Pablo Neira Ayuso | 2012-06-16 15:09:08 +0200 |
commit | 8c88f87cb27ad09086940bdd3e6955e5325ec89a (patch) | |
tree | 1acfa54ba78602eb4eb053110ffc0a54025318c7 /net/netfilter/nfnetlink_queue.c | |
parent | netfilter: add glue code to integrate nfnetlink_queue and ctnetlink (diff) | |
download | kernel-qcow2-linux-8c88f87cb27ad09086940bdd3e6955e5325ec89a.tar.gz kernel-qcow2-linux-8c88f87cb27ad09086940bdd3e6955e5325ec89a.tar.xz kernel-qcow2-linux-8c88f87cb27ad09086940bdd3e6955e5325ec89a.zip |
netfilter: nfnetlink_queue: add NAT TCP sequence adjustment if packet mangled
User-space programs that receive traffic via NFQUEUE may mangle packets.
If NAT is enabled, this usually puzzles sequence tracking, leading to
traffic disruptions.
With this patch, nfnl_queue will make the corresponding NAT TCP sequence
adjustment if:
1) The packet has been mangled,
2) the NFQA_CFG_F_CONNTRACK flag has been set, and
3) NAT is detected.
There are some records on the Internet complaning about this issue:
http://stackoverflow.com/questions/260757/packet-mangling-utilities-besides-iptables
By now, we only support TCP since we have no helpers for DCCP or SCTP.
Better to add this if we ever have some helper over those layer 4 protocols.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net/netfilter/nfnetlink_queue.c')
-rw-r--r-- | net/netfilter/nfnetlink_queue.c | 19 |
1 files changed, 11 insertions, 8 deletions
diff --git a/net/netfilter/nfnetlink_queue.c b/net/netfilter/nfnetlink_queue.c index 647923ae9230..ff82c7933dfd 100644 --- a/net/netfilter/nfnetlink_queue.c +++ b/net/netfilter/nfnetlink_queue.c @@ -502,12 +502,10 @@ err_out: } static int -nfqnl_mangle(void *data, int data_len, struct nf_queue_entry *e) +nfqnl_mangle(void *data, int data_len, struct nf_queue_entry *e, int diff) { struct sk_buff *nskb; - int diff; - diff = data_len - e->skb->len; if (diff < 0) { if (pskb_trim(e->skb, data_len)) return -ENOMEM; @@ -767,6 +765,8 @@ nfqnl_recv_verdict(struct sock *ctnl, struct sk_buff *skb, unsigned int verdict; struct nf_queue_entry *entry; struct nfq_ct_hook *nfq_ct; + enum ip_conntrack_info uninitialized_var(ctinfo); + struct nf_conn *ct = NULL; queue = instance_lookup(queue_num); if (!queue) @@ -789,20 +789,23 @@ nfqnl_recv_verdict(struct sock *ctnl, struct sk_buff *skb, nfq_ct = rcu_dereference(nfq_ct_hook); if (nfq_ct != NULL && (queue->flags & NFQA_CFG_F_CONNTRACK) && nfqa[NFQA_CT]) { - enum ip_conntrack_info ctinfo; - struct nf_conn *ct; - ct = nf_ct_get(entry->skb, &ctinfo); if (ct && !nf_ct_is_untracked(ct)) nfq_ct->parse(nfqa[NFQA_CT], ct); } - rcu_read_unlock(); if (nfqa[NFQA_PAYLOAD]) { + u16 payload_len = nla_len(nfqa[NFQA_PAYLOAD]); + int diff = payload_len - entry->skb->len; + if (nfqnl_mangle(nla_data(nfqa[NFQA_PAYLOAD]), - nla_len(nfqa[NFQA_PAYLOAD]), entry) < 0) + payload_len, entry, diff) < 0) verdict = NF_DROP; + + if (ct && (ct->status & IPS_NAT_MASK) && diff) + nfq_ct->seq_adjust(skb, ct, ctinfo, diff); } + rcu_read_unlock(); if (nfqa[NFQA_MARK]) entry->skb->mark = ntohl(nla_get_be32(nfqa[NFQA_MARK])); |