From 010c0b9f34a4c567b431f8b49a58b7332ed42e47 Mon Sep 17 00:00:00 2001 From: Patrick McHardy Date: Thu, 11 Feb 2010 12:27:09 +0100 Subject: [PATCH] netfilter: nf_nat: support mangling a single TCP packet multiple times nf_nat_mangle_tcp_packet() can currently only handle a single mangling per window because it only maintains two sequence adjustment positions: the one before the last adjustment and the one after. This patch makes sequence number adjustment tracking in nf_nat_mangle_tcp_packet() optional and allows a helper to manually update the offsets after the packet has been fully handled. Signed-off-by: Patrick McHardy --- include/net/netfilter/nf_nat_helper.h | 32 +++++++++++++++++----- net/ipv4/netfilter/nf_nat_helper.c | 39 ++++++++++++++++----------- 2 files changed, 48 insertions(+), 23 deletions(-) diff --git a/include/net/netfilter/nf_nat_helper.h b/include/net/netfilter/nf_nat_helper.h index 4222220920a5..02bb6c29dc3d 100644 --- a/include/net/netfilter/nf_nat_helper.h +++ b/include/net/netfilter/nf_nat_helper.h @@ -7,13 +7,27 @@ struct sk_buff; /* These return true or false. */ -extern int nf_nat_mangle_tcp_packet(struct sk_buff *skb, - struct nf_conn *ct, - enum ip_conntrack_info ctinfo, - unsigned int match_offset, - unsigned int match_len, - const char *rep_buffer, - unsigned int rep_len); +extern int __nf_nat_mangle_tcp_packet(struct sk_buff *skb, + struct nf_conn *ct, + enum ip_conntrack_info ctinfo, + unsigned int match_offset, + unsigned int match_len, + const char *rep_buffer, + unsigned int rep_len, bool adjust); + +static inline int nf_nat_mangle_tcp_packet(struct sk_buff *skb, + struct nf_conn *ct, + enum ip_conntrack_info ctinfo, + unsigned int match_offset, + unsigned int match_len, + const char *rep_buffer, + unsigned int rep_len) +{ + return __nf_nat_mangle_tcp_packet(skb, ct, ctinfo, + match_offset, match_len, + rep_buffer, rep_len, true); +} + extern int nf_nat_mangle_udp_packet(struct sk_buff *skb, struct nf_conn *ct, enum ip_conntrack_info ctinfo, @@ -21,6 +35,10 @@ extern int nf_nat_mangle_udp_packet(struct sk_buff *skb, unsigned int match_len, const char *rep_buffer, unsigned int rep_len); + +extern void nf_nat_set_seq_adjust(struct nf_conn *ct, + enum ip_conntrack_info ctinfo, + __be32 seq, s16 off); extern int nf_nat_seq_adjust(struct sk_buff *skb, struct nf_conn *ct, enum ip_conntrack_info ctinfo); diff --git a/net/ipv4/netfilter/nf_nat_helper.c b/net/ipv4/netfilter/nf_nat_helper.c index 7f10a6be0191..4b6af4bb1f50 100644 --- a/net/ipv4/netfilter/nf_nat_helper.c +++ b/net/ipv4/netfilter/nf_nat_helper.c @@ -141,6 +141,17 @@ static int enlarge_skb(struct sk_buff *skb, unsigned int extra) return 1; } +void nf_nat_set_seq_adjust(struct nf_conn *ct, enum ip_conntrack_info ctinfo, + __be32 seq, s16 off) +{ + if (!off) + return; + set_bit(IPS_SEQ_ADJUST_BIT, &ct->status); + adjust_tcp_sequence(ntohl(seq), off, ct, ctinfo); + nf_conntrack_event_cache(IPCT_NATSEQADJ, ct); +} +EXPORT_SYMBOL_GPL(nf_nat_set_seq_adjust); + /* Generic function for mangling variable-length address changes inside * NATed TCP connections (like the PORT XXX,XXX,XXX,XXX,XXX,XXX * command in FTP). @@ -149,14 +160,13 @@ static int enlarge_skb(struct sk_buff *skb, unsigned int extra) * skb enlargement, ... * * */ -int -nf_nat_mangle_tcp_packet(struct sk_buff *skb, - struct nf_conn *ct, - enum ip_conntrack_info ctinfo, - unsigned int match_offset, - unsigned int match_len, - const char *rep_buffer, - unsigned int rep_len) +int __nf_nat_mangle_tcp_packet(struct sk_buff *skb, + struct nf_conn *ct, + enum ip_conntrack_info ctinfo, + unsigned int match_offset, + unsigned int match_len, + const char *rep_buffer, + unsigned int rep_len, bool adjust) { struct rtable *rt = skb_rtable(skb); struct iphdr *iph; @@ -202,16 +212,13 @@ nf_nat_mangle_tcp_packet(struct sk_buff *skb, inet_proto_csum_replace2(&tcph->check, skb, htons(oldlen), htons(datalen), 1); - if (rep_len != match_len) { - set_bit(IPS_SEQ_ADJUST_BIT, &ct->status); - adjust_tcp_sequence(ntohl(tcph->seq), - (int)rep_len - (int)match_len, - ct, ctinfo); - nf_conntrack_event_cache(IPCT_NATSEQADJ, ct); - } + if (adjust && rep_len != match_len) + nf_nat_set_seq_adjust(ct, ctinfo, tcph->seq, + (int)rep_len - (int)match_len); + return 1; } -EXPORT_SYMBOL(nf_nat_mangle_tcp_packet); +EXPORT_SYMBOL(__nf_nat_mangle_tcp_packet); /* Generic function for mangling variable-length address changes inside * NATed UDP connections (like the CONNECT DATA XXXXX MESG XXXXX INDEX XXXXX -- 2.39.2