netfilter: nf_conntrack: make sequence number adjustments usuable without NAT

Split out sequence number adjustments from NAT and move them to the conntrack
core to make them usable for SYN proxying. The sequence number adjustment
information is moved to a seperate extend. The extend is added to new
conntracks when a NAT mapping is set up for a connection using a helper.

As a side effect, this saves 24 bytes per connection with NAT in the common
case that a connection does not have a helper assigned.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Tested-by: Martin Topholm <mph@one.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 3 insertions, 225 deletions

diff --git a/net/netfilter/nf_nat_helper.c b/net/netfilter/nf_nat_helper.c
index 46b9baa845a6..2840abb5bb99 100644
--- a/net/netfilter/nf_nat_helper.c
+++ b/net/netfilter/nf_nat_helper.c
@@ -20,67 +20,13 @@
 #include <net/netfilter/nf_conntrack_helper.h>
 #include <net/netfilter/nf_conntrack_ecache.h>
 #include <net/netfilter/nf_conntrack_expect.h>
+#include <net/netfilter/nf_conntrack_seqadj.h>
 #include <net/netfilter/nf_nat.h>
 #include <net/netfilter/nf_nat_l3proto.h>
 #include <net/netfilter/nf_nat_l4proto.h>
 #include <net/netfilter/nf_nat_core.h>
 #include <net/netfilter/nf_nat_helper.h>
 
-#define DUMP_OFFSET(x) \
-	pr_debug("offset_before=%d, offset_after=%d, correction_pos=%u\n", \
-		 x->offset_before, x->offset_after, x->correction_pos);
-
-/* Setup TCP sequence correction given this change at this sequence */
-static inline void
-adjust_tcp_sequence(u32 seq,
-		    int sizediff,
-		    struct nf_conn *ct,
-		    enum ip_conntrack_info ctinfo)
-{
-	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
-	struct nf_conn_nat *nat = nfct_nat(ct);
-	struct nf_nat_seq *this_way = &nat->seq[dir];
-
-	pr_debug("adjust_tcp_sequence: seq = %u, sizediff = %d\n",
-		 seq, sizediff);
-
-	pr_debug("adjust_tcp_sequence: Seq_offset before: ");
-	DUMP_OFFSET(this_way);
-
-	spin_lock_bh(&ct->lock);
-
-	/* SYN adjust. If it's uninitialized, or this is after last
-	 * correction, record it: we don't handle more than one
-	 * adjustment in the window, but do deal with common case of a
-	 * retransmit */
-	if (this_way->offset_before == this_way->offset_after ||
-	    before(this_way->correction_pos, seq)) {
-		this_way->correction_pos = seq;
-		this_way->offset_before = this_way->offset_after;
-		this_way->offset_after += sizediff;
-	}
-	spin_unlock_bh(&ct->lock);
-
-	pr_debug("adjust_tcp_sequence: Seq_offset after: ");
-	DUMP_OFFSET(this_way);
-}
-
-/* Get the offset value, for conntrack. Caller must have the conntrack locked */
-s32 nf_nat_get_offset(const struct nf_conn *ct,
-		      enum ip_conntrack_dir dir,
-		      u32 seq)
-{
-	struct nf_conn_nat *nat = nfct_nat(ct);
-	struct nf_nat_seq *this_way;
-
-	if (!nat)
-		return 0;
-
-	this_way = &nat->seq[dir];
-	return after(seq, this_way->correction_pos)
-		 ? this_way->offset_after : this_way->offset_before;
-}
-
 /* Frobs data inside this packet, which is linear. */
 static void mangle_contents(struct sk_buff *skb,
 			    unsigned int dataoff,
@@ -135,30 +81,6 @@ 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, s32 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);
-
-void nf_nat_tcp_seq_adjust(struct sk_buff *skb, struct nf_conn *ct,
-			   u32 ctinfo, int off)
-{
-	const struct tcphdr *th;
-
-	if (nf_ct_protonum(ct) != IPPROTO_TCP)
-		return;
-
-	th = (struct tcphdr *)(skb_network_header(skb)+ ip_hdrlen(skb));
-	nf_nat_set_seq_adjust(ct, ctinfo, th->seq, off);
-}
-EXPORT_SYMBOL_GPL(nf_nat_tcp_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).
@@ -203,8 +125,8 @@ int __nf_nat_mangle_tcp_packet(struct sk_buff *skb,
 			     datalen, oldlen);
 
 	if (adjust && rep_len != match_len)
-		nf_nat_set_seq_adjust(ct, ctinfo, tcph->seq,
-				      (int)rep_len - (int)match_len);
+		nf_ct_seqadj_set(ct, ctinfo, tcph->seq,
+				 (int)rep_len - (int)match_len);
 
 	return 1;
 }
@@ -264,150 +186,6 @@ nf_nat_mangle_udp_packet(struct sk_buff *skb,
 }
 EXPORT_SYMBOL(nf_nat_mangle_udp_packet);
 
-/* Adjust one found SACK option including checksum correction */
-static void
-sack_adjust(struct sk_buff *skb,
-	    struct tcphdr *tcph,
-	    unsigned int sackoff,
-	    unsigned int sackend,
-	    struct nf_nat_seq *natseq)
-{
-	while (sackoff < sackend) {
-		struct tcp_sack_block_wire *sack;
-		__be32 new_start_seq, new_end_seq;
-
-		sack = (void *)skb->data + sackoff;
-		if (after(ntohl(sack->start_seq) - natseq->offset_before,
-			  natseq->correction_pos))
-			new_start_seq = htonl(ntohl(sack->start_seq)
-					- natseq->offset_after);
-		else
-			new_start_seq = htonl(ntohl(sack->start_seq)
-					- natseq->offset_before);
-
-		if (after(ntohl(sack->end_seq) - natseq->offset_before,
-			  natseq->correction_pos))
-			new_end_seq = htonl(ntohl(sack->end_seq)
-				      - natseq->offset_after);
-		else
-			new_end_seq = htonl(ntohl(sack->end_seq)
-				      - natseq->offset_before);
-
-		pr_debug("sack_adjust: start_seq: %d->%d, end_seq: %d->%d\n",
-			 ntohl(sack->start_seq), new_start_seq,
-			 ntohl(sack->end_seq), new_end_seq);
-
-		inet_proto_csum_replace4(&tcph->check, skb,
-					 sack->start_seq, new_start_seq, 0);
-		inet_proto_csum_replace4(&tcph->check, skb,
-					 sack->end_seq, new_end_seq, 0);
-		sack->start_seq = new_start_seq;
-		sack->end_seq = new_end_seq;
-		sackoff += sizeof(*sack);
-	}
-}
-
-/* TCP SACK sequence number adjustment */
-static inline unsigned int
-nf_nat_sack_adjust(struct sk_buff *skb,
-		   unsigned int protoff,
-		   struct tcphdr *tcph,
-		   struct nf_conn *ct,
-		   enum ip_conntrack_info ctinfo)
-{
-	unsigned int dir, optoff, optend;
-	struct nf_conn_nat *nat = nfct_nat(ct);
-
-	optoff = protoff + sizeof(struct tcphdr);
-	optend = protoff + tcph->doff * 4;
-
-	if (!skb_make_writable(skb, optend))
-		return 0;
-
-	dir = CTINFO2DIR(ctinfo);
-
-	while (optoff < optend) {
-		/* Usually: option, length. */
-		unsigned char *op = skb->data + optoff;
-
-		switch (op[0]) {
-		case TCPOPT_EOL:
-			return 1;
-		case TCPOPT_NOP:
-			optoff++;
-			continue;
-		default:
-			/* no partial options */
-			if (optoff + 1 == optend ||
-			    optoff + op[1] > optend ||
-			    op[1] < 2)
-				return 0;
-			if (op[0] == TCPOPT_SACK &&
-			    op[1] >= 2+TCPOLEN_SACK_PERBLOCK &&
-			    ((op[1] - 2) % TCPOLEN_SACK_PERBLOCK) == 0)
-				sack_adjust(skb, tcph, optoff+2,
-					    optoff+op[1], &nat->seq[!dir]);
-			optoff += op[1];
-		}
-	}
-	return 1;
-}
-
-/* TCP sequence number adjustment.  Returns 1 on success, 0 on failure */
-int
-nf_nat_seq_adjust(struct sk_buff *skb,
-		  struct nf_conn *ct,
-		  enum ip_conntrack_info ctinfo,
-		  unsigned int protoff)
-{
-	struct tcphdr *tcph;
-	int dir;
-	__be32 newseq, newack;
-	s32 seqoff, ackoff;
-	struct nf_conn_nat *nat = nfct_nat(ct);
-	struct nf_nat_seq *this_way, *other_way;
-	int res;
-
-	dir = CTINFO2DIR(ctinfo);
-
-	this_way = &nat->seq[dir];
-	other_way = &nat->seq[!dir];
-
-	if (!skb_make_writable(skb, protoff + sizeof(*tcph)))
-		return 0;
-
-	tcph = (void *)skb->data + protoff;
-	spin_lock_bh(&ct->lock);
-	if (after(ntohl(tcph->seq), this_way->correction_pos))
-		seqoff = this_way->offset_after;
-	else
-		seqoff = this_way->offset_before;
-
-	if (after(ntohl(tcph->ack_seq) - other_way->offset_before,
-		  other_way->correction_pos))
-		ackoff = other_way->offset_after;
-	else
-		ackoff = other_way->offset_before;
-
-	newseq = htonl(ntohl(tcph->seq) + seqoff);
-	newack = htonl(ntohl(tcph->ack_seq) - ackoff);
-
-	inet_proto_csum_replace4(&tcph->check, skb, tcph->seq, newseq, 0);
-	inet_proto_csum_replace4(&tcph->check, skb, tcph->ack_seq, newack, 0);
-
-	pr_debug("Adjusting sequence number from %u->%u, ack from %u->%u\n",
-		 ntohl(tcph->seq), ntohl(newseq), ntohl(tcph->ack_seq),
-		 ntohl(newack));
-
-	tcph->seq = newseq;
-	tcph->ack_seq = newack;
-
-	res = nf_nat_sack_adjust(skb, protoff, tcph, ct, ctinfo);
-	spin_unlock_bh(&ct->lock);
-
-	return res;
-}
-
 /* Setup NAT on this expected conntrack so it follows master. */
 /* If we fail to get a free NAT slot, we'll get dropped on confirm */
 void nf_nat_follow_master(struct nf_conn *ct,