[net-next-2.6.git] / net / ipv4 / ip_input.c

/*
 * INET		An implementation of the TCP/IP protocol suite for the LINUX
 *		operating system.  INET is implemented using the  BSD Socket
 *		interface as the means of communication with the user level.
 *
 *		The Internet Protocol (IP) module.
 *
 * Authors:	Ross Biro
 *		Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
 *		Donald Becker, <becker@super.org>
 *		Alan Cox, <alan@lxorguk.ukuu.org.uk>
 *		Richard Underwood
 *		Stefan Becker, <stefanb@yello.ping.de>
 *		Jorge Cwik, <jorge@laser.satlink.net>
 *		Arnt Gulbrandsen, <agulbra@nvg.unit.no>
 *
 *
 * Fixes:
 *		Alan Cox	:	Commented a couple of minor bits of surplus code
 *		Alan Cox	:	Undefining IP_FORWARD doesn't include the code
 *					(just stops a compiler warning).
 *		Alan Cox	:	Frames with >=MAX_ROUTE record routes, strict routes or loose routes
 *					are junked rather than corrupting things.
 *		Alan Cox	:	Frames to bad broadcast subnets are dumped
 *					We used to process them non broadcast and
 *					boy could that cause havoc.
 *		Alan Cox	:	ip_forward sets the free flag on the
 *					new frame it queues. Still crap because
 *					it copies the frame but at least it
 *					doesn't eat memory too.
 *		Alan Cox	:	Generic queue code and memory fixes.
 *		Fred Van Kempen :	IP fragment support (borrowed from NET2E)
 *		Gerhard Koerting:	Forward fragmented frames correctly.
 *		Gerhard Koerting: 	Fixes to my fix of the above 8-).
 *		Gerhard Koerting:	IP interface addressing fix.
 *		Linus Torvalds	:	More robustness checks
 *		Alan Cox	:	Even more checks: Still not as robust as it ought to be
 *		Alan Cox	:	Save IP header pointer for later
 *		Alan Cox	:	ip option setting
 *		Alan Cox	:	Use ip_tos/ip_ttl settings
 *		Alan Cox	:	Fragmentation bogosity removed
 *					(Thanks to Mark.Bush@prg.ox.ac.uk)
 *		Dmitry Gorodchanin :	Send of a raw packet crash fix.
 *		Alan Cox	:	Silly ip bug when an overlength
 *					fragment turns up. Now frees the
 *					queue.
 *		Linus Torvalds/ :	Memory leakage on fragmentation
 *		Alan Cox	:	handling.
 *		Gerhard Koerting:	Forwarding uses IP priority hints
 *		Teemu Rantanen	:	Fragment problems.
 *		Alan Cox	:	General cleanup, comments and reformat
 *		Alan Cox	:	SNMP statistics
 *		Alan Cox	:	BSD address rule semantics. Also see
 *					UDP as there is a nasty checksum issue
 *					if you do things the wrong way.
 *		Alan Cox	:	Always defrag, moved IP_FORWARD to the config.in file
 *		Alan Cox	: 	IP options adjust sk->priority.
 *		Pedro Roque	:	Fix mtu/length error in ip_forward.
 *		Alan Cox	:	Avoid ip_chk_addr when possible.
 *	Richard Underwood	:	IP multicasting.
 *		Alan Cox	:	Cleaned up multicast handlers.
 *		Alan Cox	:	RAW sockets demultiplex in the BSD style.
 *		Gunther Mayer	:	Fix the SNMP reporting typo
 *		Alan Cox	:	Always in group 224.0.0.1
 *	Pauline Middelink	:	Fast ip_checksum update when forwarding
 *					Masquerading support.
 *		Alan Cox	:	Multicast loopback error for 224.0.0.1
 *		Alan Cox	:	IP_MULTICAST_LOOP option.
 *		Alan Cox	:	Use notifiers.
 *		Bjorn Ekwall	:	Removed ip_csum (from slhc.c too)
 *		Bjorn Ekwall	:	Moved ip_fast_csum to ip.h (inline!)
 *		Stefan Becker   :       Send out ICMP HOST REDIRECT
 *	Arnt Gulbrandsen	:	ip_build_xmit
 *		Alan Cox	:	Per socket routing cache
 *		Alan Cox	:	Fixed routing cache, added header cache.
 *		Alan Cox	:	Loopback didn't work right in original ip_build_xmit - fixed it.
 *		Alan Cox	:	Only send ICMP_REDIRECT if src/dest are the same net.
 *		Alan Cox	:	Incoming IP option handling.
 *		Alan Cox	:	Set saddr on raw output frames as per BSD.
 *		Alan Cox	:	Stopped broadcast source route explosions.
 *		Alan Cox	:	Can disable source routing
 *		Takeshi Sone    :	Masquerading didn't work.
 *	Dave Bonn,Alan Cox	:	Faster IP forwarding whenever possible.
 *		Alan Cox	:	Memory leaks, tramples, misc debugging.
 *		Alan Cox	:	Fixed multicast (by popular demand 8))
 *		Alan Cox	:	Fixed forwarding (by even more popular demand 8))
 *		Alan Cox	:	Fixed SNMP statistics [I think]
 *	Gerhard Koerting	:	IP fragmentation forwarding fix
 *		Alan Cox	:	Device lock against page fault.
 *		Alan Cox	:	IP_HDRINCL facility.
 *	Werner Almesberger	:	Zero fragment bug
 *		Alan Cox	:	RAW IP frame length bug
 *		Alan Cox	:	Outgoing firewall on build_xmit
 *		A.N.Kuznetsov	:	IP_OPTIONS support throughout the kernel
 *		Alan Cox	:	Multicast routing hooks
 *		Jos Vos		:	Do accounting *before* call_in_firewall
 *	Willy Konynenberg	:	Transparent proxying support
 *
 *
 *
 * To Fix:
 *		IP fragmentation wants rewriting cleanly. The RFC815 algorithm is much more efficient
 *		and could be made very efficient with the addition of some virtual memory hacks to permit
 *		the allocation of a buffer that can then be 'grown' by twiddling page tables.
 *		Output fragmentation wants updating along with the buffer management to use a single
 *		interleaved copy algorithm so that fragmenting has a one copy overhead. Actual packet
 *		output should probably do its own fragmentation at the UDP/RAW layer. TCP shouldn't cause
 *		fragmentation anyway.
 *
 *		This program is free software; you can redistribute it and/or
 *		modify it under the terms of the GNU General Public License
 *		as published by the Free Software Foundation; either version
 *		2 of the License, or (at your option) any later version.
 */

#include <asm/system.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/slab.h>

#include <linux/net.h>
#include <linux/socket.h>
#include <linux/sockios.h>
#include <linux/in.h>
#include <linux/inet.h>
#include <linux/inetdevice.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>

#include <net/snmp.h>
#include <net/ip.h>
#include <net/protocol.h>
#include <net/route.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <net/arp.h>
#include <net/icmp.h>
#include <net/raw.h>
#include <net/checksum.h>
#include <linux/netfilter_ipv4.h>
#include <net/xfrm.h>
#include <linux/mroute.h>
#include <linux/netlink.h>

/*
 *	Process Router Attention IP option
 */
int ip_call_ra_chain(struct sk_buff *skb)
{
	struct ip_ra_chain *ra;
	u8 protocol = ip_hdr(skb)->protocol;
	struct sock *last = NULL;
	struct net_device *dev = skb->dev;

	read_lock(&ip_ra_lock);
	for (ra = ip_ra_chain; ra; ra = ra->next) {
		struct sock *sk = ra->sk;

		/* If socket is bound to an interface, only report
		 * the packet if it came  from that interface.
		 */
		if (sk && inet_sk(sk)->inet_num == protocol &&
		    (!sk->sk_bound_dev_if ||
		     sk->sk_bound_dev_if == dev->ifindex) &&
		    net_eq(sock_net(sk), dev_net(dev))) {
			if (ip_hdr(skb)->frag_off & htons(IP_MF | IP_OFFSET)) {
				if (ip_defrag(skb, IP_DEFRAG_CALL_RA_CHAIN)) {
					read_unlock(&ip_ra_lock);
					return 1;
				}
			}
			if (last) {
				struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
				if (skb2)
					raw_rcv(last, skb2);
			}
			last = sk;
		}
	}

	if (last) {
		raw_rcv(last, skb);
		read_unlock(&ip_ra_lock);
		return 1;
	}
	read_unlock(&ip_ra_lock);
	return 0;
}

static int ip_local_deliver_finish(struct sk_buff *skb)
{
	struct net *net = dev_net(skb->dev);

	__skb_pull(skb, ip_hdrlen(skb));

	/* Point into the IP datagram, just past the header. */
	skb_reset_transport_header(skb);

	rcu_read_lock();
	{
		int protocol = ip_hdr(skb)->protocol;
		int hash, raw;
		const struct net_protocol *ipprot;

	resubmit:
		raw = raw_local_deliver(skb, protocol);

		hash = protocol & (MAX_INET_PROTOS - 1);
		ipprot = rcu_dereference(inet_protos[hash]);
		if (ipprot != NULL) {
			int ret;

			if (!net_eq(net, &init_net) && !ipprot->netns_ok) {
				if (net_ratelimit())
					printk("%s: proto %d isn't netns-ready\n",
						__func__, protocol);
				kfree_skb(skb);
				goto out;
			}

			if (!ipprot->no_policy) {
				if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
					kfree_skb(skb);
					goto out;
				}
				nf_reset(skb);
			}
			ret = ipprot->handler(skb);
			if (ret < 0) {
				protocol = -ret;
				goto resubmit;
			}
			IP_INC_STATS_BH(net, IPSTATS_MIB_INDELIVERS);
		} else {
			if (!raw) {
				if (xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
					IP_INC_STATS_BH(net, IPSTATS_MIB_INUNKNOWNPROTOS);
					icmp_send(skb, ICMP_DEST_UNREACH,
						  ICMP_PROT_UNREACH, 0);
				}
			} else
				IP_INC_STATS_BH(net, IPSTATS_MIB_INDELIVERS);
			kfree_skb(skb);
		}
	}
 out:
	rcu_read_unlock();

	return 0;
}

/*
 * 	Deliver IP Packets to the higher protocol layers.
 */
int ip_local_deliver(struct sk_buff *skb)
{
	/*
	 *	Reassemble IP fragments.
	 */

	if (ip_hdr(skb)->frag_off & htons(IP_MF | IP_OFFSET)) {
		if (ip_defrag(skb, IP_DEFRAG_LOCAL_DELIVER))
			return 0;
	}

	return NF_HOOK(PF_INET, NF_INET_LOCAL_IN, skb, skb->dev, NULL,
		       ip_local_deliver_finish);
}

static inline int ip_rcv_options(struct sk_buff *skb)
{
	struct ip_options *opt;
	struct iphdr *iph;
	struct net_device *dev = skb->dev;

	/* It looks as overkill, because not all
	   IP options require packet mangling.
	   But it is the easiest for now, especially taking
	   into account that combination of IP options
	   and running sniffer is extremely rare condition.
					      --ANK (980813)
	*/
	if (skb_cow(skb, skb_headroom(skb))) {
		IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
		goto drop;
	}

	iph = ip_hdr(skb);
	opt = &(IPCB(skb)->opt);
	opt->optlen = iph->ihl*4 - sizeof(struct iphdr);

	if (ip_options_compile(dev_net(dev), opt, skb)) {
		IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INHDRERRORS);
		goto drop;
	}

	if (unlikely(opt->srr)) {
		struct in_device *in_dev = in_dev_get(dev);
		if (in_dev) {
			if (!IN_DEV_SOURCE_ROUTE(in_dev)) {
				if (IN_DEV_LOG_MARTIANS(in_dev) &&
				    net_ratelimit())
					printk(KERN_INFO "source route option %pI4 -> %pI4\n",
					       &iph->saddr, &iph->daddr);
				in_dev_put(in_dev);
				goto drop;
			}

			in_dev_put(in_dev);
		}

		if (ip_options_rcv_srr(skb))
			goto drop;
	}

	return 0;
drop:
	return -1;
}

static int ip_rcv_finish(struct sk_buff *skb)
{
	const struct iphdr *iph = ip_hdr(skb);
	struct rtable *rt;

	/*
	 *	Initialise the virtual path cache for the packet. It describes
	 *	how the packet travels inside Linux networking.
	 */
	if (skb_dst(skb) == NULL) {
		int err = ip_route_input(skb, iph->daddr, iph->saddr, iph->tos,
					 skb->dev);
		if (unlikely(err)) {
			if (err == -EHOSTUNREACH)
				IP_INC_STATS_BH(dev_net(skb->dev),
						IPSTATS_MIB_INADDRERRORS);
			else if (err == -ENETUNREACH)
				IP_INC_STATS_BH(dev_net(skb->dev),
						IPSTATS_MIB_INNOROUTES);
			goto drop;
		}
	}

#ifdef CONFIG_NET_CLS_ROUTE
	if (unlikely(skb_dst(skb)->tclassid)) {
		struct ip_rt_acct *st = per_cpu_ptr(ip_rt_acct, smp_processor_id());
		u32 idx = skb_dst(skb)->tclassid;
		st[idx&0xFF].o_packets++;
		st[idx&0xFF].o_bytes += skb->len;
		st[(idx>>16)&0xFF].i_packets++;
		st[(idx>>16)&0xFF].i_bytes += skb->len;
	}
#endif

	if (iph->ihl > 5 && ip_rcv_options(skb))
		goto drop;

	rt = skb_rtable(skb);
	if (rt->rt_type == RTN_MULTICAST) {
		IP_UPD_PO_STATS_BH(dev_net(rt->u.dst.dev), IPSTATS_MIB_INMCAST,
				skb->len);
	} else if (rt->rt_type == RTN_BROADCAST)
		IP_UPD_PO_STATS_BH(dev_net(rt->u.dst.dev), IPSTATS_MIB_INBCAST,
				skb->len);

	return dst_input(skb);

drop:
	kfree_skb(skb);
	return NET_RX_DROP;
}

/*
 * 	Main IP Receive routine.
 */
int ip_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev)
{
	struct iphdr *iph;
	u32 len;

	/* When the interface is in promisc. mode, drop all the crap
	 * that it receives, do not try to analyse it.
	 */
	if (skb->pkt_type == PACKET_OTHERHOST)
		goto drop;


	IP_UPD_PO_STATS_BH(dev_net(dev), IPSTATS_MIB_IN, skb->len);

	if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL) {
		IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
		goto out;
	}

	if (!pskb_may_pull(skb, sizeof(struct iphdr)))
		goto inhdr_error;

	iph = ip_hdr(skb);

	/*
	 *	RFC1122: 3.2.1.2 MUST silently discard any IP frame that fails the checksum.
	 *
	 *	Is the datagram acceptable?
	 *
	 *	1.	Length at least the size of an ip header
	 *	2.	Version of 4
	 *	3.	Checksums correctly. [Speed optimisation for later, skip loopback checksums]
	 *	4.	Doesn't have a bogus length
	 */

	if (iph->ihl < 5 || iph->version != 4)
		goto inhdr_error;

	if (!pskb_may_pull(skb, iph->ihl*4))
		goto inhdr_error;

	iph = ip_hdr(skb);

	if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
		goto inhdr_error;

	len = ntohs(iph->tot_len);
	if (skb->len < len) {
		IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INTRUNCATEDPKTS);
		goto drop;
	} else if (len < (iph->ihl*4))
		goto inhdr_error;

	/* Our transport medium may have padded the buffer out. Now we know it
	 * is IP we can trim to the true length of the frame.
	 * Note this now means skb->len holds ntohs(iph->tot_len).
	 */
	if (pskb_trim_rcsum(skb, len)) {
		IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
		goto drop;
	}

	/* Remove any debris in the socket control block */
	memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));

	/* Must drop socket now because of tproxy. */
	skb_orphan(skb);

	return NF_HOOK(PF_INET, NF_INET_PRE_ROUTING, skb, dev, NULL,
		       ip_rcv_finish);

inhdr_error:
	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INHDRERRORS);
drop:
	kfree_skb(skb);
out:
	return NET_RX_DROP;
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* INET An implementation of the TCP/IP protocol suite for the LINUX
	3	* operating system. INET is implemented using the BSD Socket
	4	* interface as the means of communication with the user level.
	5	*
	6	* The Internet Protocol (IP) module.
	7	*
02c30a84	8	* Authors: Ross Biro
1da177e4 LT	9	* Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
1da177e4 LT	10	* Donald Becker, <becker@super.org>
113aa838	11	* Alan Cox, <alan@lxorguk.ukuu.org.uk>
1da177e4 LT	12	* Richard Underwood
	13	* Stefan Becker, <stefanb@yello.ping.de>
	14	* Jorge Cwik, <jorge@laser.satlink.net>
	15	* Arnt Gulbrandsen, <agulbra@nvg.unit.no>
e905a9ed	16	*
1da177e4 LT	17	*
	18	* Fixes:
	19	* Alan Cox : Commented a couple of minor bits of surplus code
	20	* Alan Cox : Undefining IP_FORWARD doesn't include the code
	21	* (just stops a compiler warning).
	22	* Alan Cox : Frames with >=MAX_ROUTE record routes, strict routes or loose routes
	23	* are junked rather than corrupting things.
	24	* Alan Cox : Frames to bad broadcast subnets are dumped
	25	* We used to process them non broadcast and
	26	* boy could that cause havoc.
	27	* Alan Cox : ip_forward sets the free flag on the
	28	* new frame it queues. Still crap because
	29	* it copies the frame but at least it
	30	* doesn't eat memory too.
	31	* Alan Cox : Generic queue code and memory fixes.
	32	* Fred Van Kempen : IP fragment support (borrowed from NET2E)
	33	* Gerhard Koerting: Forward fragmented frames correctly.
	34	* Gerhard Koerting: Fixes to my fix of the above 8-).
	35	* Gerhard Koerting: IP interface addressing fix.
	36	* Linus Torvalds : More robustness checks
	37	* Alan Cox : Even more checks: Still not as robust as it ought to be
	38	* Alan Cox : Save IP header pointer for later
	39	* Alan Cox : ip option setting
	40	* Alan Cox : Use ip_tos/ip_ttl settings
	41	* Alan Cox : Fragmentation bogosity removed
	42	* (Thanks to Mark.Bush@prg.ox.ac.uk)
	43	* Dmitry Gorodchanin : Send of a raw packet crash fix.
	44	* Alan Cox : Silly ip bug when an overlength
	45	* fragment turns up. Now frees the
	46	* queue.
	47	* Linus Torvalds/ : Memory leakage on fragmentation
	48	* Alan Cox : handling.
	49	* Gerhard Koerting: Forwarding uses IP priority hints
	50	* Teemu Rantanen : Fragment problems.
	51	* Alan Cox : General cleanup, comments and reformat
	52	* Alan Cox : SNMP statistics
	53	* Alan Cox : BSD address rule semantics. Also see
	54	* UDP as there is a nasty checksum issue
	55	* if you do things the wrong way.
	56	* Alan Cox : Always defrag, moved IP_FORWARD to the config.in file
	57	* Alan Cox : IP options adjust sk->priority.
	58	* Pedro Roque : Fix mtu/length error in ip_forward.
	59	* Alan Cox : Avoid ip_chk_addr when possible.
	60	* Richard Underwood : IP multicasting.
	61	* Alan Cox : Cleaned up multicast handlers.
	62	* Alan Cox : RAW sockets demultiplex in the BSD style.
	63	* Gunther Mayer : Fix the SNMP reporting typo
	64	* Alan Cox : Always in group 224.0.0.1
	65	* Pauline Middelink : Fast ip_checksum update when forwarding
	66	* Masquerading support.
	67	* Alan Cox : Multicast loopback error for 224.0.0.1
	68	* Alan Cox : IP_MULTICAST_LOOP option.
	69	* Alan Cox : Use notifiers.
	70	* Bjorn Ekwall : Removed ip_csum (from slhc.c too)
	71	* Bjorn Ekwall : Moved ip_fast_csum to ip.h (inline!)
	72	* Stefan Becker : Send out ICMP HOST REDIRECT
	73	* Arnt Gulbrandsen : ip_build_xmit
	74	* Alan Cox : Per socket routing cache
	75	* Alan Cox : Fixed routing cache, added header cache.
	76	* Alan Cox : Loopback didn't work right in original ip_build_xmit - fixed it.
	77	* Alan Cox : Only send ICMP_REDIRECT if src/dest are the same net.
	78	* Alan Cox : Incoming IP option handling.
	79	* Alan Cox : Set saddr on raw output frames as per BSD.
	80	* Alan Cox : Stopped broadcast source route explosions.
81	* Alan Cox : Can disable source routing
82	* Takeshi Sone : Masquerading didn't work.
83	* Dave Bonn,Alan Cox : Faster IP forwarding whenever possible.
84	* Alan Cox : Memory leaks, tramples, misc debugging.
85	* Alan Cox : Fixed multicast (by popular demand 8))
86	* Alan Cox : Fixed forwarding (by even more popular demand 8))
87	* Alan Cox : Fixed SNMP statistics [I think]
88	* Gerhard Koerting : IP fragmentation forwarding fix
89	* Alan Cox : Device lock against page fault.
90	* Alan Cox : IP_HDRINCL facility.
91	* Werner Almesberger : Zero fragment bug
92	* Alan Cox : RAW IP frame length bug
93	* Alan Cox : Outgoing firewall on build_xmit
94	* A.N.Kuznetsov : IP_OPTIONS support throughout the kernel
95	* Alan Cox : Multicast routing hooks
96	* Jos Vos : Do accounting before call_in_firewall
97	* Willy Konynenberg : Transparent proxying support
98	*
e905a9ed	99	*
1da177e4 LT	100	*
	101	* To Fix:
	102	* IP fragmentation wants rewriting cleanly. The RFC815 algorithm is much more efficient
	103	* and could be made very efficient with the addition of some virtual memory hacks to permit
	104	* the allocation of a buffer that can then be 'grown' by twiddling page tables.
e905a9ed	105	* Output fragmentation wants updating along with the buffer management to use a single
1da177e4 LT	106	* interleaved copy algorithm so that fragmenting has a one copy overhead. Actual packet
	107	* output should probably do its own fragmentation at the UDP/RAW layer. TCP shouldn't cause
	108	* fragmentation anyway.
	109	*
	110	* This program is free software; you can redistribute it and/or
	111	* modify it under the terms of the GNU General Public License
	112	* as published by the Free Software Foundation; either version
	113	* 2 of the License, or (at your option) any later version.
	114	*/
	115
	116	#include <asm/system.h>
	117	#include <linux/module.h>
	118	#include <linux/types.h>
	119	#include <linux/kernel.h>
	120	#include <linux/string.h>
	121	#include <linux/errno.h>
5a0e3ad6	122	#include <linux/slab.h>
1da177e4 LT	123
	124	#include <linux/net.h>
	125	#include <linux/socket.h>
	126	#include <linux/sockios.h>
	127	#include <linux/in.h>
	128	#include <linux/inet.h>
14c85021	129	#include <linux/inetdevice.h>
1da177e4 LT	130	#include <linux/netdevice.h>
	131	#include <linux/etherdevice.h>
	132
	133	#include <net/snmp.h>
	134	#include <net/ip.h>
	135	#include <net/protocol.h>
	136	#include <net/route.h>
	137	#include <linux/skbuff.h>
	138	#include <net/sock.h>
	139	#include <net/arp.h>
	140	#include <net/icmp.h>
	141	#include <net/raw.h>
	142	#include <net/checksum.h>
	143	#include <linux/netfilter_ipv4.h>
	144	#include <net/xfrm.h>
	145	#include <linux/mroute.h>
	146	#include <linux/netlink.h>
	147
1da177e4 LT	148	/*
1da177e4 LT	149	* Process Router Attention IP option
e905a9ed	150	*/
1da177e4 LT	151	int ip_call_ra_chain(struct sk_buff *skb)
	152	{
	153	struct ip_ra_chain *ra;
eddc9ec5	154	u8 protocol = ip_hdr(skb)->protocol;
1da177e4	155	struct sock *last = NULL;
cb84663e	156	struct net_device *dev = skb->dev;
1da177e4 LT	157
	158	read_lock(&ip_ra_lock);
	159	for (ra = ip_ra_chain; ra; ra = ra->next) {
	160	struct sock *sk = ra->sk;
	161
	162	/* If socket is bound to an interface, only report
	163	* the packet if it came from that interface.
	164	*/
c720c7e8	165	if (sk && inet_sk(sk)->inet_num == protocol &&
1da177e4	166	(!sk->sk_bound_dev_if \|\|
cb84663e	167	sk->sk_bound_dev_if == dev->ifindex) &&
09ad9bc7	168	net_eq(sock_net(sk), dev_net(dev))) {
eddc9ec5	169	if (ip_hdr(skb)->frag_off & htons(IP_MF \| IP_OFFSET)) {
776c729e	170	if (ip_defrag(skb, IP_DEFRAG_CALL_RA_CHAIN)) {
1da177e4 LT	171	read_unlock(&ip_ra_lock);
	172	return 1;
	173	}
	174	}
	175	if (last) {
	176	struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
	177	if (skb2)
	178	raw_rcv(last, skb2);
	179	}
	180	last = sk;
	181	}
	182	}
	183
	184	if (last) {
	185	raw_rcv(last, skb);
	186	read_unlock(&ip_ra_lock);
	187	return 1;
	188	}
	189	read_unlock(&ip_ra_lock);
	190	return 0;
	191	}
	192
861d0486	193	static int ip_local_deliver_finish(struct sk_buff *skb)
1da177e4	194	{
c346dca1	195	struct net *net = dev_net(skb->dev);
f145049a	196
c9bdd4b5	197	__skb_pull(skb, ip_hdrlen(skb));
1da177e4	198
e905a9ed	199	/* Point into the IP datagram, just past the header. */
badff6d0	200	skb_reset_transport_header(skb);
1da177e4 LT	201
	202	rcu_read_lock();
	203	{
eddc9ec5	204	int protocol = ip_hdr(skb)->protocol;
7bc54c90	205	int hash, raw;
32613090	206	const struct net_protocol *ipprot;
1da177e4 LT	207
1da177e4 LT	208	resubmit:
7bc54c90	209	raw = raw_local_deliver(skb, protocol);
1da177e4	210
7bc54c90	211	hash = protocol & (MAX_INET_PROTOS - 1);
f145049a	212	ipprot = rcu_dereference(inet_protos[hash]);
9c0188ac	213	if (ipprot != NULL) {
1da177e4 LT	214	int ret;
1da177e4 LT	215
9c0188ac AD	216	if (!net_eq(net, &init_net) && !ipprot->netns_ok) {
	217	if (net_ratelimit())
	218	printk("%s: proto %d isn't netns-ready\n",
	219	__func__, protocol);
	220	kfree_skb(skb);
	221	goto out;
	222	}
	223
b59c2701 PM	224	if (!ipprot->no_policy) {
	225	if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
	226	kfree_skb(skb);
	227	goto out;
	228	}
	229	nf_reset(skb);
1da177e4 LT	230	}
	231	ret = ipprot->handler(skb);
	232	if (ret < 0) {
	233	protocol = -ret;
	234	goto resubmit;
	235	}
7c73a6fa	236	IP_INC_STATS_BH(net, IPSTATS_MIB_INDELIVERS);
1da177e4	237	} else {
7bc54c90	238	if (!raw) {
1da177e4	239	if (xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
7c73a6fa	240	IP_INC_STATS_BH(net, IPSTATS_MIB_INUNKNOWNPROTOS);
1da177e4 LT	241	icmp_send(skb, ICMP_DEST_UNREACH,
	242	ICMP_PROT_UNREACH, 0);
	243	}
	244	} else
7c73a6fa	245	IP_INC_STATS_BH(net, IPSTATS_MIB_INDELIVERS);
1da177e4 LT	246	kfree_skb(skb);
	247	}
	248	}
	249	out:
	250	rcu_read_unlock();
	251
	252	return 0;
	253	}
	254
	255	/*
	256	* Deliver IP Packets to the higher protocol layers.
e905a9ed	257	*/
1da177e4 LT	258	int ip_local_deliver(struct sk_buff *skb)
	259	{
	260	/*
	261	* Reassemble IP fragments.
	262	*/
	263
eddc9ec5	264	if (ip_hdr(skb)->frag_off & htons(IP_MF \| IP_OFFSET)) {
776c729e	265	if (ip_defrag(skb, IP_DEFRAG_LOCAL_DELIVER))
1da177e4 LT	266	return 0;
	267	}
	268
6e23ae2a	269	return NF_HOOK(PF_INET, NF_INET_LOCAL_IN, skb, skb->dev, NULL,
1da177e4 LT	270	ip_local_deliver_finish);
	271	}
	272
d245407e TG	273	static inline int ip_rcv_options(struct sk_buff *skb)
	274	{
	275	struct ip_options *opt;
	276	struct iphdr *iph;
	277	struct net_device *dev = skb->dev;
	278
	279	/* It looks as overkill, because not all
	280	IP options require packet mangling.
	281	But it is the easiest for now, especially taking
	282	into account that combination of IP options
	283	and running sniffer is extremely rare condition.
	284	--ANK (980813)
	285	*/
	286	if (skb_cow(skb, skb_headroom(skb))) {
7c73a6fa	287	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
d245407e TG	288	goto drop;
	289	}
	290
eddc9ec5	291	iph = ip_hdr(skb);
22aba383 DL	292	opt = &(IPCB(skb)->opt);
22aba383 DL	293	opt->optlen = iph->ihl*4 - sizeof(struct iphdr);
d245407e	294
c346dca1	295	if (ip_options_compile(dev_net(dev), opt, skb)) {
7c73a6fa	296	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INHDRERRORS);
d245407e TG	297	goto drop;
	298	}
	299
d245407e TG	300	if (unlikely(opt->srr)) {
	301	struct in_device *in_dev = in_dev_get(dev);
	302	if (in_dev) {
	303	if (!IN_DEV_SOURCE_ROUTE(in_dev)) {
	304	if (IN_DEV_LOG_MARTIANS(in_dev) &&
	305	net_ratelimit())
673d57e7 HH	306	printk(KERN_INFO "source route option %pI4 -> %pI4\n",
673d57e7 HH	307	&iph->saddr, &iph->daddr);
d245407e TG	308	in_dev_put(in_dev);
	309	goto drop;
	310	}
	311
	312	in_dev_put(in_dev);
	313	}
	314
	315	if (ip_options_rcv_srr(skb))
	316	goto drop;
	317	}
	318
	319	return 0;
	320	drop:
	321	return -1;
	322	}
	323
861d0486	324	static int ip_rcv_finish(struct sk_buff *skb)
1da177e4	325	{
eddc9ec5	326	const struct iphdr *iph = ip_hdr(skb);
5506b54b	327	struct rtable *rt;
1da177e4 LT	328
	329	/*
	330	* Initialise the virtual path cache for the packet. It describes
	331	* how the packet travels inside Linux networking.
e905a9ed	332	*/
adf30907	333	if (skb_dst(skb) == NULL) {
3e192bea TG	334	int err = ip_route_input(skb, iph->daddr, iph->saddr, iph->tos,
	335	skb->dev);
	336	if (unlikely(err)) {
2c2910a4	337	if (err == -EHOSTUNREACH)
7c73a6fa PE	338	IP_INC_STATS_BH(dev_net(skb->dev),
7c73a6fa PE	339	IPSTATS_MIB_INADDRERRORS);
e91a47eb	340	else if (err == -ENETUNREACH)
7c73a6fa PE	341	IP_INC_STATS_BH(dev_net(skb->dev),
7c73a6fa PE	342	IPSTATS_MIB_INNOROUTES);
e905a9ed	343	goto drop;
2c2910a4	344	}
1da177e4 LT	345	}
	346
	347	#ifdef CONFIG_NET_CLS_ROUTE
adf30907	348	if (unlikely(skb_dst(skb)->tclassid)) {
8dbde28d	349	struct ip_rt_acct *st = per_cpu_ptr(ip_rt_acct, smp_processor_id());
adf30907	350	u32 idx = skb_dst(skb)->tclassid;
1da177e4	351	st[idx&0xFF].o_packets++;
fd3f8c4c	352	st[idx&0xFF].o_bytes += skb->len;
1da177e4	353	st[(idx>>16)&0xFF].i_packets++;
fd3f8c4c	354	st[(idx>>16)&0xFF].i_bytes += skb->len;
1da177e4 LT	355	}
	356	#endif
	357
d245407e TG	358	if (iph->ihl > 5 && ip_rcv_options(skb))
d245407e TG	359	goto drop;
1da177e4	360
511c3f92	361	rt = skb_rtable(skb);
edf391ff NH	362	if (rt->rt_type == RTN_MULTICAST) {
	363	IP_UPD_PO_STATS_BH(dev_net(rt->u.dst.dev), IPSTATS_MIB_INMCAST,
	364	skb->len);
	365	} else if (rt->rt_type == RTN_BROADCAST)
	366	IP_UPD_PO_STATS_BH(dev_net(rt->u.dst.dev), IPSTATS_MIB_INBCAST,
	367	skb->len);
5506b54b	368
1da177e4 LT	369	return dst_input(skb);
1da177e4 LT	370
1da177e4	371	drop:
e905a9ed YH	372	kfree_skb(skb);
e905a9ed YH	373	return NET_RX_DROP;
1da177e4 LT	374	}
	375
	376	/*
	377	* Main IP Receive routine.
e905a9ed	378	*/
f2ccd8fa	379	int ip_rcv(struct sk_buff skb, struct net_device dev, struct packet_type pt, struct net_device orig_dev)
1da177e4 LT	380	{
1da177e4 LT	381	struct iphdr *iph;
58615242	382	u32 len;
1da177e4 LT	383
	384	/* When the interface is in promisc. mode, drop all the crap
	385	* that it receives, do not try to analyse it.
	386	*/
	387	if (skb->pkt_type == PACKET_OTHERHOST)
	388	goto drop;
	389
edf391ff NH	390
edf391ff NH	391	IP_UPD_PO_STATS_BH(dev_net(dev), IPSTATS_MIB_IN, skb->len);
1da177e4 LT	392
1da177e4 LT	393	if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL) {
7c73a6fa	394	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
1da177e4 LT	395	goto out;
	396	}
	397
	398	if (!pskb_may_pull(skb, sizeof(struct iphdr)))
	399	goto inhdr_error;
	400
eddc9ec5	401	iph = ip_hdr(skb);
1da177e4 LT	402
1da177e4 LT	403	/*
c67fa027	404	* RFC1122: 3.2.1.2 MUST silently discard any IP frame that fails the checksum.
1da177e4 LT	405	*
	406	* Is the datagram acceptable?
	407	*
	408	* 1. Length at least the size of an ip header
	409	* 2. Version of 4
	410	* 3. Checksums correctly. [Speed optimisation for later, skip loopback checksums]
	411	* 4. Doesn't have a bogus length
	412	*/
	413
	414	if (iph->ihl < 5 \|\| iph->version != 4)
58615242	415	goto inhdr_error;
1da177e4 LT	416
	417	if (!pskb_may_pull(skb, iph->ihl*4))
	418	goto inhdr_error;
	419
eddc9ec5	420	iph = ip_hdr(skb);
1da177e4	421
e9c60422	422	if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
58615242	423	goto inhdr_error;
1da177e4	424
58615242	425	len = ntohs(iph->tot_len);
704aed53	426	if (skb->len < len) {
7c73a6fa	427	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INTRUNCATEDPKTS);
704aed53 MC	428	goto drop;
704aed53 MC	429	} else if (len < (iph->ihl*4))
58615242	430	goto inhdr_error;
1da177e4	431
58615242 TG	432	/* Our transport medium may have padded the buffer out. Now we know it
	433	* is IP we can trim to the true length of the frame.
	434	* Note this now means skb->len holds ntohs(iph->tot_len).
	435	*/
	436	if (pskb_trim_rcsum(skb, len)) {
7c73a6fa	437	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
58615242	438	goto drop;
1da177e4 LT	439	}
1da177e4 LT	440
53602f92	441	/* Remove any debris in the socket control block */
d569f1d7	442	memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
53602f92	443
71f9dacd HX	444	/* Must drop socket now because of tproxy. */
	445	skb_orphan(skb);
	446
6e23ae2a	447	return NF_HOOK(PF_INET, NF_INET_PRE_ROUTING, skb, dev, NULL,
1da177e4 LT	448	ip_rcv_finish);
	449
	450	inhdr_error:
7c73a6fa	451	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INHDRERRORS);
1da177e4	452	drop:
e905a9ed	453	kfree_skb(skb);
1da177e4	454	out:
e905a9ed	455	return NET_RX_DROP;
1da177e4	456	}