[NETFILTER]: nf_conntrack: make l3proto->prepare() generic and renames it

The icmp[v6] l4proto modules parse headers in ICMP[v6] error to get tuple.
But they have to find the offset to transport protocol header before that.
Their processings are almost same as prepare() of l3proto modules.
This makes prepare() more generic to simplify icmp[v6] l4proto module
later.

Signed-off-by: Yasuyuki Kozakai <yasuyuki.kozakai@toshiba.co.jp>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 36 insertions, 26 deletions

diff --git a/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c b/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c
index 3c56299..ee29f4e 100644
--- a/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c
+++ b/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c
@@ -78,21 +78,26 @@ nf_ct_ipv4_gather_frags(struct sk_buff *skb, u_int32_t user)
 	return skb;
 }
 
-static int
-ipv4_prepare(struct sk_buff **pskb, unsigned int hooknum, unsigned int *dataoff,
-	     u_int8_t *protonum)
+static int ipv4_get_l4proto(const struct sk_buff *skb, unsigned int nhoff,
+			    unsigned int *dataoff, u_int8_t *protonum)
 {
+	struct iphdr _iph, *iph;
+
+	iph = skb_header_pointer(skb, nhoff, sizeof(_iph), &_iph);
+	if (iph == NULL)
+		return -NF_DROP;
+
 	/* Never happen */
-	if (ip_hdr(*pskb)->frag_off & htons(IP_OFFSET)) {
+	if (iph->frag_off & htons(IP_OFFSET)) {
 		if (net_ratelimit()) {
-			printk(KERN_ERR "ipv4_prepare: Frag of proto %u (hook=%u)\n",
-			ip_hdr(*pskb)->protocol, hooknum);
+			printk(KERN_ERR "ipv4_get_l4proto: Frag of proto %u\n",
+			iph->protocol);
 		}
 		return -NF_DROP;
 	}
 
-	*dataoff = skb_network_offset(*pskb) + ip_hdrlen(*pskb);
-	*protonum = ip_hdr(*pskb)->protocol;
+	*dataoff = nhoff + (iph->ihl << 2);
+	*protonum = iph->protocol;
 
 	return NF_ACCEPT;
 }
@@ -407,7 +412,7 @@ struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv4 = {
 	.invert_tuple	 = ipv4_invert_tuple,
 	.print_tuple	 = ipv4_print_tuple,
 	.print_conntrack = ipv4_print_conntrack,
-	.prepare	 = ipv4_prepare,
+	.get_l4proto	 = ipv4_get_l4proto,
 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 	.tuple_to_nfattr = ipv4_tuple_to_nfattr,
 	.nfattr_to_tuple = ipv4_nfattr_to_tuple,
diff --git a/net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c b/net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c
index b5c4bb5..9b7eaaa 100644
--- a/net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c
+++ b/net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c
@@ -86,7 +86,7 @@ static int ipv6_print_conntrack(struct seq_file *s,
  *        - Note also special handling of AUTH header. Thanks to IPsec wizards.
  */
 
-int nf_ct_ipv6_skip_exthdr(struct sk_buff *skb, int start, u8 *nexthdrp,
+int nf_ct_ipv6_skip_exthdr(const struct sk_buff *skb, int start, u8 *nexthdrp,
 			   int len)
 {
 	u8 nexthdr = *nexthdrp;
@@ -117,19 +117,24 @@ int nf_ct_ipv6_skip_exthdr(struct sk_buff *skb, int start, u8 *nexthdrp,
 	return start;
 }
 
-static int
-ipv6_prepare(struct sk_buff **pskb, unsigned int hooknum, unsigned int *dataoff,
-	     u_int8_t *protonum)
+static int ipv6_get_l4proto(const struct sk_buff *skb, unsigned int nhoff,
+			    unsigned int *dataoff, u_int8_t *protonum)
 {
-	unsigned int extoff = (u8 *)(ipv6_hdr(*pskb) + 1) - (*pskb)->data;
-	unsigned char pnum = ipv6_hdr(*pskb)->nexthdr;
-	int protoff = nf_ct_ipv6_skip_exthdr(*pskb, extoff, &pnum,
-					     (*pskb)->len - extoff);
+	unsigned int extoff = nhoff + sizeof(struct ipv6hdr);
+	unsigned char pnum;
+	int protoff;
+
+	if (skb_copy_bits(skb, nhoff + offsetof(struct ipv6hdr, nexthdr),
+			  &pnum, sizeof(pnum)) != 0) {
+		pr_debug("ip6_conntrack_core: can't get nexthdr\n");
+		return -NF_ACCEPT;
+	}
+	protoff = nf_ct_ipv6_skip_exthdr(skb, extoff, &pnum, skb->len - extoff);
 	/*
-	 * (protoff == (*pskb)->len) mean that the packet doesn't have no data
+	 * (protoff == skb->len) mean that the packet doesn't have no data
 	 * except of IPv6 & ext headers. but it's tracked anyway. - YK
 	 */
-	if ((protoff < 0) || (protoff > (*pskb)->len)) {
+	if ((protoff < 0) || (protoff > skb->len)) {
 		pr_debug("ip6_conntrack_core: can't find proto in pkt\n");
 		return -NF_ACCEPT;
 	}
@@ -375,7 +380,7 @@ struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv6 = {
 	.invert_tuple		= ipv6_invert_tuple,
 	.print_tuple		= ipv6_print_tuple,
 	.print_conntrack	= ipv6_print_conntrack,
-	.prepare		= ipv6_prepare,
+	.get_l4proto		= ipv6_get_l4proto,
 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 	.tuple_to_nfattr	= ipv6_tuple_to_nfattr,
 	.nfattr_to_tuple	= ipv6_nfattr_to_tuple,
diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index b730413..5b194e3 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -622,8 +622,9 @@ nf_conntrack_in(int pf, unsigned int hooknum, struct sk_buff **pskb)
 
 	/* rcu_read_lock()ed by nf_hook_slow */
 	l3proto = __nf_ct_l3proto_find((u_int16_t)pf);
-
-	if ((ret = l3proto->prepare(pskb, hooknum, &dataoff, &protonum)) <= 0) {
+	ret = l3proto->get_l4proto(*pskb, skb_network_offset(*pskb),
+				   &dataoff, &protonum);
+	if (ret <= 0) {
 		pr_debug("not prepared to track yet or error occured\n");
 		NF_CT_STAT_INC_ATOMIC(error);
 		NF_CT_STAT_INC_ATOMIC(invalid);
diff --git a/net/netfilter/nf_conntrack_l3proto_generic.c b/net/netfilter/nf_conntrack_l3proto_generic.c
index b1bfa20..0691642 100644
--- a/net/netfilter/nf_conntrack_l3proto_generic.c
+++ b/net/netfilter/nf_conntrack_l3proto_generic.c
@@ -61,9 +61,8 @@ static int generic_print_conntrack(struct seq_file *s,
 	return 0;
 }
 
-static int
-generic_prepare(struct sk_buff **pskb, unsigned int hooknum,
-		unsigned int *dataoff, u_int8_t *protonum)
+static int generic_get_l4proto(const struct sk_buff *skb, unsigned int nhoff,
+			       unsigned int *dataoff, u_int8_t *protonum)
 {
 	/* Never track !!! */
 	return -NF_ACCEPT;
@@ -77,6 +76,6 @@ struct nf_conntrack_l3proto nf_conntrack_l3proto_generic = {
 	.invert_tuple	 = generic_invert_tuple,
 	.print_tuple	 = generic_print_tuple,
 	.print_conntrack = generic_print_conntrack,
-	.prepare	 = generic_prepare,
+	.get_l4proto	 = generic_get_l4proto,
 };
 EXPORT_SYMBOL_GPL(nf_conntrack_l3proto_generic);