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Commit 6816d931 authored by Florian Westphal's avatar Florian Westphal Committed by Pablo Neira Ayuso
Browse files

netfilter: conntrack: remove get_l4proto indirection from l3 protocol trackers 



Handle it in the core instead.

ipv6_skip_exthdr() is built-in even if ipv6 is a module, i.e. this
doesn't create an ipv6 dependency.

Signed-off-by: default avatarFlorian Westphal <fw@strlen.de>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent d1b6fe94

include/net/netfilter/nf_conntrack_l3proto.h

+0 −8
Original line number Diff line number Diff line
@@ -24,14 +24,6 @@ struct nf_conntrack_l3proto { 
	/* size of tuple nlattr, fills a hole */

	u16 nla_size;



	/*

	 * Called before tracking. 

	 *	*dataoff: offset of protocol header (TCP, UDP,...) in skb

	 *	*protonum: protocol number

	 */

	int (*get_l4proto)(const struct sk_buff *skb, unsigned int nhoff,

			   unsigned int *dataoff, u_int8_t *protonum);



	/* Called when netns wants to use connection tracking */

	int (*net_ns_get)(struct net *);

	void (*net_ns_put)(struct net *);

net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c

+0 −30
Original line number Diff line number Diff line
@@ -38,35 +38,6 @@ struct conntrack4_net { 
	unsigned int users;

};



static int ipv4_get_l4proto(const struct sk_buff *skb, unsigned int nhoff,

			    unsigned int *dataoff, u_int8_t *protonum)

{

	const struct iphdr *iph;

	struct iphdr _iph;



	iph = skb_header_pointer(skb, nhoff, sizeof(_iph), &_iph);

	if (iph == NULL)

		return -NF_ACCEPT;



	/* Conntrack defragments packets, we might still see fragments

	 * inside ICMP packets though. */

	if (iph->frag_off & htons(IP_OFFSET))

		return -NF_ACCEPT;



	*dataoff = nhoff + (iph->ihl << 2);

	*protonum = iph->protocol;



	/* Check bogus IP headers */

	if (*dataoff > skb->len) {

		pr_debug("nf_conntrack_ipv4: bogus IPv4 packet: "

			 "nhoff %u, ihl %u, skblen %u\n",

			 nhoff, iph->ihl << 2, skb->len);

		return -NF_ACCEPT;

	}



	return NF_ACCEPT;

}



static unsigned int ipv4_helper(void *priv,

				struct sk_buff *skb,

				const struct nf_hook_state *state)
@@ -297,7 +268,6 @@ static void ipv4_hooks_unregister(struct net *net) 


const struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv4 = {

	.l3proto	 = PF_INET,

	.get_l4proto	 = ipv4_get_l4proto,

	.net_ns_get	 = ipv4_hooks_register,

	.net_ns_put	 = ipv4_hooks_unregister,

	.me		 = THIS_MODULE,

net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c

+0 −29
Original line number Diff line number Diff line
@@ -41,34 +41,6 @@ struct conntrack6_net { 
	unsigned int users;

};



static int ipv6_get_l4proto(const struct sk_buff *skb, unsigned int nhoff,

			    unsigned int *dataoff, u_int8_t *protonum)

{

	unsigned int extoff = nhoff + sizeof(struct ipv6hdr);

	__be16 frag_off;

	int protoff;

	u8 nexthdr;



	if (skb_copy_bits(skb, nhoff + offsetof(struct ipv6hdr, nexthdr),

			  &nexthdr, sizeof(nexthdr)) != 0) {

		pr_debug("ip6_conntrack_core: can't get nexthdr\n");

		return -NF_ACCEPT;

	}

	protoff = ipv6_skip_exthdr(skb, extoff, &nexthdr, &frag_off);

	/*

	 * (protoff == skb->len) means the packet has not data, just

	 * IPv6 and possibly extensions headers, but it is tracked anyway

	 */

	if (protoff < 0 || (frag_off & htons(~0x7)) != 0) {

		pr_debug("ip6_conntrack_core: can't find proto in pkt\n");

		return -NF_ACCEPT;

	}



	*dataoff = protoff;

	*protonum = nexthdr;

	return NF_ACCEPT;

}



static unsigned int ipv6_helper(void *priv,

				struct sk_buff *skb,

				const struct nf_hook_state *state)
@@ -281,7 +253,6 @@ static void ipv6_hooks_unregister(struct net *net) 


const struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv6 = {

	.l3proto		= PF_INET6,

	.get_l4proto		= ipv6_get_l4proto,

	.net_ns_get		= ipv6_hooks_register,

	.net_ns_put		= ipv6_hooks_unregister,

	.me			= THIS_MODULE,

net/netfilter/Makefile

+1 −1
Original line number Diff line number Diff line 
# SPDX-License-Identifier: GPL-2.0

netfilter-objs := core.o nf_log.o nf_queue.o nf_sockopt.o utils.o



nf_conntrack-y	:= nf_conntrack_core.o nf_conntrack_standalone.o nf_conntrack_expect.o nf_conntrack_helper.o nf_conntrack_proto.o nf_conntrack_l3proto_generic.o nf_conntrack_proto_generic.o nf_conntrack_proto_tcp.o nf_conntrack_proto_udp.o nf_conntrack_extend.o nf_conntrack_acct.o nf_conntrack_seqadj.o

nf_conntrack-y	:= nf_conntrack_core.o nf_conntrack_standalone.o nf_conntrack_expect.o nf_conntrack_helper.o nf_conntrack_proto.o nf_conntrack_proto_generic.o nf_conntrack_proto_tcp.o nf_conntrack_proto_udp.o nf_conntrack_extend.o nf_conntrack_acct.o nf_conntrack_seqadj.o

nf_conntrack-$(CONFIG_NF_CONNTRACK_TIMEOUT) += nf_conntrack_timeout.o

nf_conntrack-$(CONFIG_NF_CONNTRACK_TIMESTAMP) += nf_conntrack_timestamp.o

nf_conntrack-$(CONFIG_NF_CONNTRACK_EVENTS) += nf_conntrack_ecache.o

net/netfilter/nf_conntrack_core.c

+88 −20
Original line number Diff line number Diff line
@@ -37,7 +37,6 @@ 
#include <linux/rculist_nulls.h>



#include <net/netfilter/nf_conntrack.h>

#include <net/netfilter/nf_conntrack_l3proto.h>

#include <net/netfilter/nf_conntrack_l4proto.h>

#include <net/netfilter/nf_conntrack_expect.h>

#include <net/netfilter/nf_conntrack_helper.h>
@@ -55,6 +54,7 @@ 
#include <net/netfilter/nf_nat_core.h>

#include <net/netfilter/nf_nat_helper.h>

#include <net/netns/hash.h>

#include <net/ip.h>



#include "nf_internals.h"
@@ -273,21 +273,94 @@ nf_ct_get_tuple(const struct sk_buff *skb, 
	return l4proto->pkt_to_tuple(skb, dataoff, net, tuple);

}



static int ipv4_get_l4proto(const struct sk_buff *skb, unsigned int nhoff,

			    u_int8_t *protonum)

{

	int dataoff = -1;

#if IS_ENABLED(CONFIG_NF_CONNTRACK_IPV4)

	const struct iphdr *iph;

	struct iphdr _iph;



	iph = skb_header_pointer(skb, nhoff, sizeof(_iph), &_iph);

	if (!iph)

		return -1;



	/* Conntrack defragments packets, we might still see fragments

	 * inside ICMP packets though.

	 */

	if (iph->frag_off & htons(IP_OFFSET))

		return -1;



	dataoff = nhoff + (iph->ihl << 2);

	*protonum = iph->protocol;



	/* Check bogus IP headers */

	if (dataoff > skb->len) {

		pr_debug("bogus IPv4 packet: nhoff %u, ihl %u, skblen %u\n",

			 nhoff, iph->ihl << 2, skb->len);

		return -1;

	}

#endif

	return dataoff;

}



static int ipv6_get_l4proto(const struct sk_buff *skb, unsigned int nhoff,

			    u8 *protonum)

{

	int protoff = -1;

#if IS_ENABLED(CONFIG_NF_CONNTRACK_IPV6)

	unsigned int extoff = nhoff + sizeof(struct ipv6hdr);

	__be16 frag_off;

	u8 nexthdr;



	if (skb_copy_bits(skb, nhoff + offsetof(struct ipv6hdr, nexthdr),

			  &nexthdr, sizeof(nexthdr)) != 0) {

		pr_debug("can't get nexthdr\n");

		return -1;

	}

	protoff = ipv6_skip_exthdr(skb, extoff, &nexthdr, &frag_off);

	/*

	 * (protoff == skb->len) means the packet has not data, just

	 * IPv6 and possibly extensions headers, but it is tracked anyway

	 */

	if (protoff < 0 || (frag_off & htons(~0x7)) != 0) {

		pr_debug("can't find proto in pkt\n");

		return -1;

	}



	*protonum = nexthdr;

#endif

	return protoff;

}



static int get_l4proto(const struct sk_buff *skb,

		       unsigned int nhoff, u8 pf, u8 *l4num)

{

	switch (pf) {

	case NFPROTO_IPV4:

		return ipv4_get_l4proto(skb, nhoff, l4num);

	case NFPROTO_IPV6:

		return ipv6_get_l4proto(skb, nhoff, l4num);

	default:

		*l4num = 0;

		break;

	}

	return -1;

}



bool nf_ct_get_tuplepr(const struct sk_buff *skb, unsigned int nhoff,

		       u_int16_t l3num,

		       struct net *net, struct nf_conntrack_tuple *tuple)

{

	const struct nf_conntrack_l3proto *l3proto;

	const struct nf_conntrack_l4proto *l4proto;

	unsigned int protoff;

	u_int8_t protonum;

	u8 protonum;

	int protoff;

	int ret;



	rcu_read_lock();



	l3proto = __nf_ct_l3proto_find(l3num);

	ret = l3proto->get_l4proto(skb, nhoff, &protoff, &protonum);

	if (ret != NF_ACCEPT) {

	protoff = get_l4proto(skb, nhoff, l3num, &protonum);

	if (protoff <= 0) {

		rcu_read_unlock();

		return false;

	}
@@ -1397,14 +1470,12 @@ unsigned int 
nf_conntrack_in(struct net *net, u_int8_t pf, unsigned int hooknum,

		struct sk_buff *skb)

{

	const struct nf_conntrack_l3proto *l3proto;

	const struct nf_conntrack_l4proto *l4proto;

	struct nf_conn *ct, *tmpl;

	enum ip_conntrack_info ctinfo;

	unsigned int *timeouts;

	unsigned int dataoff;

	u_int8_t protonum;

	int ret;

	int dataoff, ret;



	tmpl = nf_ct_get(skb, &ctinfo);

	if (tmpl || ctinfo == IP_CT_UNTRACKED) {
@@ -1418,14 +1489,12 @@ nf_conntrack_in(struct net *net, u_int8_t pf, unsigned int hooknum, 
	}



	/* rcu_read_lock()ed by nf_hook_thresh */

	l3proto = __nf_ct_l3proto_find(pf);

	ret = l3proto->get_l4proto(skb, skb_network_offset(skb),

				   &dataoff, &protonum);

	if (ret <= 0) {

	dataoff = get_l4proto(skb, skb_network_offset(skb), pf, &protonum);

	if (dataoff <= 0) {

		pr_debug("not prepared to track yet or error occurred\n");

		NF_CT_STAT_INC_ATOMIC(net, error);

		NF_CT_STAT_INC_ATOMIC(net, invalid);

		ret = -ret;

		ret = NF_ACCEPT;

		goto out;

	}
@@ -1641,14 +1710,14 @@ static void nf_conntrack_attach(struct sk_buff *nskb, const struct sk_buff *skb) 


static int nf_conntrack_update(struct net *net, struct sk_buff *skb)

{

	const struct nf_conntrack_l3proto *l3proto;

	const struct nf_conntrack_l4proto *l4proto;

	struct nf_conntrack_tuple_hash *h;

	struct nf_conntrack_tuple tuple;

	enum ip_conntrack_info ctinfo;

	struct nf_nat_hook *nat_hook;

	unsigned int dataoff, status;

	unsigned int status;

	struct nf_conn *ct;

	int dataoff;

	u16 l3num;

	u8 l4num;
@@ -1657,10 +1726,9 @@ static int nf_conntrack_update(struct net *net, struct sk_buff *skb) 
		return 0;



	l3num = nf_ct_l3num(ct);

	l3proto = nf_ct_l3proto_find_get(l3num);



	if (l3proto->get_l4proto(skb, skb_network_offset(skb), &dataoff,

				 &l4num) <= 0)

	dataoff = get_l4proto(skb, skb_network_offset(skb), l3num, &l4num);

	if (dataoff <= 0)

		return -1;



	l4proto = nf_ct_l4proto_find_get(l3num, l4num);