netfilter: add protocol independent NAT core

Convert the IPv4 NAT implementation to a protocol independent core and
address family specific modules.

Signed-off-by: Patrick McHardy <kaber@trash.net>

1 files changed, 0 insertions, 461 deletions

diff --git a/net/ipv4/netfilter/nf_nat_helper.c b/net/ipv4/netfilter/nf_nat_helper.c
deleted file mode 100644
index 2fefec5e757c..000000000000
--- a/net/ipv4/netfilter/nf_nat_helper.c
+++ /dev/null
@@ -1,461 +0,0 @@
-/* ip_nat_helper.c - generic support functions for NAT helpers
- *
- * (C) 2000-2002 Harald Welte <laforge@netfilter.org>
- * (C) 2003-2006 Netfilter Core Team <coreteam@netfilter.org>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- */
-#include <linux/module.h>
-#include <linux/gfp.h>
-#include <linux/kmod.h>
-#include <linux/types.h>
-#include <linux/timer.h>
-#include <linux/skbuff.h>
-#include <linux/tcp.h>
-#include <linux/udp.h>
-#include <net/checksum.h>
-#include <net/tcp.h>
-#include <net/route.h>
-
-#include <linux/netfilter_ipv4.h>
-#include <net/netfilter/nf_conntrack.h>
-#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_nat.h>
-#include <net/netfilter/nf_nat_protocol.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);
-
-static DEFINE_SPINLOCK(nf_nat_seqofs_lock);
-
-/* 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(&nf_nat_seqofs_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(&nf_nat_seqofs_lock);
-
-	pr_debug("adjust_tcp_sequence: Seq_offset after: ");
-	DUMP_OFFSET(this_way);
-}
-
-/* Get the offset value, for conntrack */
-s16 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;
-	s16 offset;
-
-	if (!nat)
-		return 0;
-
-	this_way = &nat->seq[dir];
-	spin_lock_bh(&nf_nat_seqofs_lock);
-	offset = after(seq, this_way->correction_pos)
-		 ? this_way->offset_after : this_way->offset_before;
-	spin_unlock_bh(&nf_nat_seqofs_lock);
-
-	return offset;
-}
-EXPORT_SYMBOL_GPL(nf_nat_get_offset);
-
-/* Frobs data inside this packet, which is linear. */
-static void mangle_contents(struct sk_buff *skb,
-			    unsigned int dataoff,
-			    unsigned int match_offset,
-			    unsigned int match_len,
-			    const char *rep_buffer,
-			    unsigned int rep_len)
-{
-	unsigned char *data;
-
-	BUG_ON(skb_is_nonlinear(skb));
-	data = skb_network_header(skb) + dataoff;
-
-	/* move post-replacement */
-	memmove(data + match_offset + rep_len,
-		data + match_offset + match_len,
-		skb->tail - (skb->network_header + dataoff +
-			     match_offset + match_len));
-
-	/* insert data from buffer */
-	memcpy(data + match_offset, rep_buffer, rep_len);
-
-	/* update skb info */
-	if (rep_len > match_len) {
-		pr_debug("nf_nat_mangle_packet: Extending packet by "
-			 "%u from %u bytes\n", rep_len - match_len, skb->len);
-		skb_put(skb, rep_len - match_len);
-	} else {
-		pr_debug("nf_nat_mangle_packet: Shrinking packet from "
-			 "%u from %u bytes\n", match_len - rep_len, skb->len);
-		__skb_trim(skb, skb->len + rep_len - match_len);
-	}
-
-	/* fix IP hdr checksum information */
-	ip_hdr(skb)->tot_len = htons(skb->len);
-	ip_send_check(ip_hdr(skb));
-}
-
-/* Unusual, but possible case. */
-static int enlarge_skb(struct sk_buff *skb, unsigned int extra)
-{
-	if (skb->len + extra > 65535)
-		return 0;
-
-	if (pskb_expand_head(skb, 0, extra - skb_tailroom(skb), GFP_ATOMIC))
-		return 0;
-
-	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);
-
-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);
-
-static void nf_nat_csum(struct sk_buff *skb, const struct iphdr *iph, void *data,
-			int datalen, __sum16 *check, int oldlen)
-{
-	struct rtable *rt = skb_rtable(skb);
-
-	if (skb->ip_summed != CHECKSUM_PARTIAL) {
-		if (!(rt->rt_flags & RTCF_LOCAL) &&
-		    (!skb->dev || skb->dev->features & NETIF_F_V4_CSUM)) {
-			skb->ip_summed = CHECKSUM_PARTIAL;
-			skb->csum_start = skb_headroom(skb) +
-					  skb_network_offset(skb) +
-					  iph->ihl * 4;
-			skb->csum_offset = (void *)check - data;
-			*check = ~csum_tcpudp_magic(iph->saddr, iph->daddr,
-						    datalen, iph->protocol, 0);
-		} else {
-			*check = 0;
-			*check = csum_tcpudp_magic(iph->saddr, iph->daddr,
-						   datalen, iph->protocol,
-						   csum_partial(data, datalen,
-								0));
-			if (iph->protocol == IPPROTO_UDP && !*check)
-				*check = CSUM_MANGLED_0;
-		}
-	} else
-		inet_proto_csum_replace2(check, skb,
-					 htons(oldlen), htons(datalen), 1);
-}
-
-/* Generic function for mangling variable-length address changes inside
- * NATed TCP connections (like the PORT XXX,XXX,XXX,XXX,XXX,XXX
- * command in FTP).
- *
- * Takes care about all the nasty sequence number changes, checksumming,
- * skb enlargement, ...
- *
- * */
-int __nf_nat_mangle_tcp_packet(struct sk_buff *skb,
-			       struct nf_conn *ct,
-			       enum ip_conntrack_info ctinfo,
-			       unsigned int protoff,
-			       unsigned int match_offset,
-			       unsigned int match_len,
-			       const char *rep_buffer,
-			       unsigned int rep_len, bool adjust)
-{
-	struct iphdr *iph;
-	struct tcphdr *tcph;
-	int oldlen, datalen;
-
-	if (!skb_make_writable(skb, skb->len))
-		return 0;
-
-	if (rep_len > match_len &&
-	    rep_len - match_len > skb_tailroom(skb) &&
-	    !enlarge_skb(skb, rep_len - match_len))
-		return 0;
-
-	SKB_LINEAR_ASSERT(skb);
-
-	iph = ip_hdr(skb);
-	tcph = (void *)iph + iph->ihl*4;
-
-	oldlen = skb->len - iph->ihl*4;
-	mangle_contents(skb, iph->ihl*4 + tcph->doff*4,
-			match_offset, match_len, rep_buffer, rep_len);
-
-	datalen = skb->len - iph->ihl*4;
-	nf_nat_csum(skb, iph, tcph, datalen, &tcph->check, oldlen);
-
-	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);
-
-/* Generic function for mangling variable-length address changes inside
- * NATed UDP connections (like the CONNECT DATA XXXXX MESG XXXXX INDEX XXXXX
- * command in the Amanda protocol)
- *
- * Takes care about all the nasty sequence number changes, checksumming,
- * skb enlargement, ...
- *
- * XXX - This function could be merged with nf_nat_mangle_tcp_packet which
- *       should be fairly easy to do.
- */
-int
-nf_nat_mangle_udp_packet(struct sk_buff *skb,
-			 struct nf_conn *ct,
-			 enum ip_conntrack_info ctinfo,
-			 unsigned int protoff,
-			 unsigned int match_offset,
-			 unsigned int match_len,
-			 const char *rep_buffer,
-			 unsigned int rep_len)
-{
-	struct iphdr *iph;
-	struct udphdr *udph;
-	int datalen, oldlen;
-
-	if (!skb_make_writable(skb, skb->len))
-		return 0;
-
-	if (rep_len > match_len &&
-	    rep_len - match_len > skb_tailroom(skb) &&
-	    !enlarge_skb(skb, rep_len - match_len))
-		return 0;
-
-	iph = ip_hdr(skb);
-	udph = (void *)iph + iph->ihl*4;
-
-	oldlen = skb->len - iph->ihl*4;
-	mangle_contents(skb, iph->ihl*4 + sizeof(*udph),
-			match_offset, match_len, rep_buffer, rep_len);
-
-	/* update the length of the UDP packet */
-	datalen = skb->len - iph->ihl*4;
-	udph->len = htons(datalen);
-
-	/* fix udp checksum if udp checksum was previously calculated */
-	if (!udph->check && skb->ip_summed != CHECKSUM_PARTIAL)
-		return 1;
-
-	nf_nat_csum(skb, iph, udph, datalen, &udph->check, oldlen);
-
-	return 1;
-}
-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,
-		   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 = ip_hdrlen(skb) + sizeof(struct tcphdr);
-	optend = ip_hdrlen(skb) + 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;
-	s16 seqoff, ackoff;
-	struct nf_conn_nat *nat = nfct_nat(ct);
-	struct nf_nat_seq *this_way, *other_way;
-
-	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;
-	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;
-
-	return nf_nat_sack_adjust(skb, tcph, ct, ctinfo);
-}
-
-/* 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,
-			  struct nf_conntrack_expect *exp)
-{
-	struct nf_nat_ipv4_range range;
-
-	/* This must be a fresh one. */
-	BUG_ON(ct->status & IPS_NAT_DONE_MASK);
-
-	/* Change src to where master sends to */
-	range.flags = NF_NAT_RANGE_MAP_IPS;
-	range.min_ip = range.max_ip
-		= ct->master->tuplehash[!exp->dir].tuple.dst.u3.ip;
-	nf_nat_setup_info(ct, &range, NF_NAT_MANIP_SRC);
-
-	/* For DST manip, map port here to where it's expected. */
-	range.flags = (NF_NAT_RANGE_MAP_IPS | NF_NAT_RANGE_PROTO_SPECIFIED);
-	range.min = range.max = exp->saved_proto;
-	range.min_ip = range.max_ip
-		= ct->master->tuplehash[!exp->dir].tuple.src.u3.ip;
-	nf_nat_setup_info(ct, &range, NF_NAT_MANIP_DST);
-}
-EXPORT_SYMBOL(nf_nat_follow_master);