[linux-2.6-block.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.
 *
 * Version:	$Id: ip_input.c,v 1.55 2002/01/12 07:39:45 davem Exp $
 *
 * Authors:	Ross Biro
 *		Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
 *		Donald Becker, <becker@super.org>
 *		Alan Cox, <Alan.Cox@linux.org>
 *		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/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>

/*
 *	SNMP management statistics
 */

DEFINE_SNMP_STAT(struct ipstats_mib, ip_statistics) __read_mostly;

/*
 *	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;

	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)->num == protocol &&
		    (!sk->sk_bound_dev_if ||
		     sk->sk_bound_dev_if == skb->dev->ifindex)) {
			if (ip_hdr(skb)->frag_off & htons(IP_MF | IP_OFFSET)) {
				skb = ip_defrag(skb, IP_DEFRAG_CALL_RA_CHAIN);
				if (skb == NULL) {
					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 inline int ip_local_deliver_finish(struct sk_buff *skb)
{
	__skb_pull(skb, ip_hdrlen(skb));

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

	rcu_read_lock();
	{
		/* Note: See raw.c and net/raw.h, RAWV4_HTABLE_SIZE==MAX_INET_PROTOS */
		int protocol = ip_hdr(skb)->protocol;
		int hash;
		struct sock *raw_sk;
		struct net_protocol *ipprot;

	resubmit:
		hash = protocol & (MAX_INET_PROTOS - 1);
		raw_sk = sk_head(&raw_v4_htable[hash]);

		/* If there maybe a raw socket we must check - if not we
		 * don't care less
		 */
		if (raw_sk && !raw_v4_input(skb, ip_hdr(skb), hash))
			raw_sk = NULL;

		if ((ipprot = rcu_dereference(inet_protos[hash])) != NULL) {
			int ret;

			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(IPSTATS_MIB_INDELIVERS);
		} else {
			if (!raw_sk) {
				if (xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
					IP_INC_STATS_BH(IPSTATS_MIB_INUNKNOWNPROTOS);
					icmp_send(skb, ICMP_DEST_UNREACH,
						  ICMP_PROT_UNREACH, 0);
				}
			} else
				IP_INC_STATS_BH(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)) {
		skb = ip_defrag(skb, IP_DEFRAG_LOCAL_DELIVER);
		if (!skb)
			return 0;
	}

	return NF_HOOK(PF_INET, NF_IP_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(IPSTATS_MIB_INDISCARDS);
		goto drop;
	}

	iph = ip_hdr(skb);

	if (ip_options_compile(NULL, skb)) {
		IP_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
		goto drop;
	}

	opt = &(IPCB(skb)->opt);
	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 "
					       "%u.%u.%u.%u -> %u.%u.%u.%u\n",
					       NIPQUAD(iph->saddr),
					       NIPQUAD(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 inline 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 == 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(IPSTATS_MIB_INADDRERRORS);
			else if (err == -ENETUNREACH)
				IP_INC_STATS_BH(IPSTATS_MIB_INNOROUTES);
			goto drop;
		}
	}

#ifdef CONFIG_NET_CLS_ROUTE
	if (unlikely(skb->dst->tclassid)) {
		struct ip_rt_acct *st = ip_rt_acct + 256*smp_processor_id();
		u32 idx = skb->dst->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 = (struct rtable*)skb->dst;
	if (rt->rt_type == RTN_MULTICAST)
		IP_INC_STATS_BH(IPSTATS_MIB_INMCASTPKTS);
	else if (rt->rt_type == RTN_BROADCAST)
		IP_INC_STATS_BH(IPSTATS_MIB_INBCASTPKTS);

	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;

	if (dev->nd_net != &init_net)
		goto drop;

	/* 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_INC_STATS_BH(IPSTATS_MIB_INRECEIVES);

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

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

	iph = ip_hdr(skb);

	/*
	 *	RFC1122: 3.1.2.2 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(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(IPSTATS_MIB_INDISCARDS);
		goto drop;
	}

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

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

inhdr_error:
	IP_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
drop:
	kfree_skb(skb);
out:
	return NET_RX_DROP;
}

EXPORT_SYMBOL(ip_statistics);
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	*
	8	* Version: $Id: ip_input.c,v 1.55 2002/01/12 07:39:45 davem Exp $
	9	*
02c30a84	10	* Authors: Ross Biro
1da177e4 LT	11	* Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
	12	* Donald Becker, <becker@super.org>
	13	* Alan Cox, <Alan.Cox@linux.org>
	14	* Richard Underwood
	15	* Stefan Becker, <stefanb@yello.ping.de>
	16	* Jorge Cwik, <jorge@laser.satlink.net>
	17	* Arnt Gulbrandsen, <agulbra@nvg.unit.no>
e905a9ed	18	*
1da177e4 LT	19	*
	20	* Fixes:
	21	* Alan Cox : Commented a couple of minor bits of surplus code
	22	* Alan Cox : Undefining IP_FORWARD doesn't include the code
	23	* (just stops a compiler warning).
	24	* Alan Cox : Frames with >=MAX_ROUTE record routes, strict routes or loose routes
	25	* are junked rather than corrupting things.
	26	* Alan Cox : Frames to bad broadcast subnets are dumped
	27	* We used to process them non broadcast and
	28	* boy could that cause havoc.
	29	* Alan Cox : ip_forward sets the free flag on the
	30	* new frame it queues. Still crap because
	31	* it copies the frame but at least it
	32	* doesn't eat memory too.
	33	* Alan Cox : Generic queue code and memory fixes.
	34	* Fred Van Kempen : IP fragment support (borrowed from NET2E)
	35	* Gerhard Koerting: Forward fragmented frames correctly.
	36	* Gerhard Koerting: Fixes to my fix of the above 8-).
	37	* Gerhard Koerting: IP interface addressing fix.
	38	* Linus Torvalds : More robustness checks
	39	* Alan Cox : Even more checks: Still not as robust as it ought to be
	40	* Alan Cox : Save IP header pointer for later
	41	* Alan Cox : ip option setting
	42	* Alan Cox : Use ip_tos/ip_ttl settings
	43	* Alan Cox : Fragmentation bogosity removed
	44	* (Thanks to Mark.Bush@prg.ox.ac.uk)
	45	* Dmitry Gorodchanin : Send of a raw packet crash fix.
	46	* Alan Cox : Silly ip bug when an overlength
	47	* fragment turns up. Now frees the
	48	* queue.
	49	* Linus Torvalds/ : Memory leakage on fragmentation
	50	* Alan Cox : handling.
	51	* Gerhard Koerting: Forwarding uses IP priority hints
	52	* Teemu Rantanen : Fragment problems.
	53	* Alan Cox : General cleanup, comments and reformat
	54	* Alan Cox : SNMP statistics
	55	* Alan Cox : BSD address rule semantics. Also see
	56	* UDP as there is a nasty checksum issue
	57	* if you do things the wrong way.
	58	* Alan Cox : Always defrag, moved IP_FORWARD to the config.in file
	59	* Alan Cox : IP options adjust sk->priority.
	60	* Pedro Roque : Fix mtu/length error in ip_forward.
	61	* Alan Cox : Avoid ip_chk_addr when possible.
	62	* Richard Underwood : IP multicasting.
	63	* Alan Cox : Cleaned up multicast handlers.
	64	* Alan Cox : RAW sockets demultiplex in the BSD style.
	65	* Gunther Mayer : Fix the SNMP reporting typo
	66	* Alan Cox : Always in group 224.0.0.1
	67	* Pauline Middelink : Fast ip_checksum update when forwarding
	68	* Masquerading support.
	69	* Alan Cox : Multicast loopback error for 224.0.0.1
	70	* Alan Cox : IP_MULTICAST_LOOP option.
	71	* Alan Cox : Use notifiers.
	72	* Bjorn Ekwall : Removed ip_csum (from slhc.c too)
	73	* Bjorn Ekwall : Moved ip_fast_csum to ip.h (inline!)
	74	* Stefan Becker : Send out ICMP HOST REDIRECT
	75	* Arnt Gulbrandsen : ip_build_xmit
	76	* Alan Cox : Per socket routing cache
	77	* Alan Cox : Fixed routing cache, added header cache.
	78	* Alan Cox : Loopback didn't work right in original ip_build_xmit - fixed it.
	79	* Alan Cox : Only send ICMP_REDIRECT if src/dest are the same net.
	80	* Alan Cox : Incoming IP option handling.
	81	* Alan Cox : Set saddr on raw output frames as per BSD.
	82	* Alan Cox : Stopped broadcast source route explosions.
83	* Alan Cox : Can disable source routing
84	* Takeshi Sone : Masquerading didn't work.
85	* Dave Bonn,Alan Cox : Faster IP forwarding whenever possible.
86	* Alan Cox : Memory leaks, tramples, misc debugging.
87	* Alan Cox : Fixed multicast (by popular demand 8))
88	* Alan Cox : Fixed forwarding (by even more popular demand 8))
89	* Alan Cox : Fixed SNMP statistics [I think]
90	* Gerhard Koerting : IP fragmentation forwarding fix
91	* Alan Cox : Device lock against page fault.
92	* Alan Cox : IP_HDRINCL facility.
93	* Werner Almesberger : Zero fragment bug
94	* Alan Cox : RAW IP frame length bug
95	* Alan Cox : Outgoing firewall on build_xmit
96	* A.N.Kuznetsov : IP_OPTIONS support throughout the kernel
97	* Alan Cox : Multicast routing hooks
98	* Jos Vos : Do accounting before call_in_firewall
99	* Willy Konynenberg : Transparent proxying support
100	*
e905a9ed	101	*
1da177e4 LT	102	*
	103	* To Fix:
	104	* IP fragmentation wants rewriting cleanly. The RFC815 algorithm is much more efficient
	105	* and could be made very efficient with the addition of some virtual memory hacks to permit
	106	* the allocation of a buffer that can then be 'grown' by twiddling page tables.
e905a9ed	107	* Output fragmentation wants updating along with the buffer management to use a single
1da177e4 LT	108	* interleaved copy algorithm so that fragmenting has a one copy overhead. Actual packet
	109	* output should probably do its own fragmentation at the UDP/RAW layer. TCP shouldn't cause
	110	* fragmentation anyway.
	111	*
	112	* This program is free software; you can redistribute it and/or
	113	* modify it under the terms of the GNU General Public License
	114	* as published by the Free Software Foundation; either version
	115	* 2 of the License, or (at your option) any later version.
	116	*/
	117
	118	#include <asm/system.h>
	119	#include <linux/module.h>
	120	#include <linux/types.h>
	121	#include <linux/kernel.h>
	122	#include <linux/string.h>
	123	#include <linux/errno.h>
1da177e4 LT	124
	125	#include <linux/net.h>
	126	#include <linux/socket.h>
	127	#include <linux/sockios.h>
	128	#include <linux/in.h>
	129	#include <linux/inet.h>
14c85021	130	#include <linux/inetdevice.h>
1da177e4 LT	131	#include <linux/netdevice.h>
	132	#include <linux/etherdevice.h>
	133
	134	#include <net/snmp.h>
	135	#include <net/ip.h>
	136	#include <net/protocol.h>
	137	#include <net/route.h>
	138	#include <linux/skbuff.h>
	139	#include <net/sock.h>
	140	#include <net/arp.h>
	141	#include <net/icmp.h>
	142	#include <net/raw.h>
	143	#include <net/checksum.h>
	144	#include <linux/netfilter_ipv4.h>
	145	#include <net/xfrm.h>
	146	#include <linux/mroute.h>
	147	#include <linux/netlink.h>
	148
	149	/*
	150	* SNMP management statistics
	151	*/
	152
ba89966c	153	DEFINE_SNMP_STAT(struct ipstats_mib, ip_statistics) __read_mostly;
1da177e4 LT	154
	155	/*
	156	* Process Router Attention IP option
e905a9ed	157	*/
1da177e4 LT	158	int ip_call_ra_chain(struct sk_buff *skb)
	159	{
	160	struct ip_ra_chain *ra;
eddc9ec5	161	u8 protocol = ip_hdr(skb)->protocol;
1da177e4 LT	162	struct sock *last = NULL;
	163
	164	read_lock(&ip_ra_lock);
	165	for (ra = ip_ra_chain; ra; ra = ra->next) {
	166	struct sock *sk = ra->sk;
	167
	168	/* If socket is bound to an interface, only report
	169	* the packet if it came from that interface.
	170	*/
	171	if (sk && inet_sk(sk)->num == protocol &&
	172	(!sk->sk_bound_dev_if \|\|
	173	sk->sk_bound_dev_if == skb->dev->ifindex)) {
eddc9ec5	174	if (ip_hdr(skb)->frag_off & htons(IP_MF \| IP_OFFSET)) {
1da177e4 LT	175	skb = ip_defrag(skb, IP_DEFRAG_CALL_RA_CHAIN);
	176	if (skb == NULL) {
	177	read_unlock(&ip_ra_lock);
	178	return 1;
	179	}
	180	}
	181	if (last) {
	182	struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
	183	if (skb2)
	184	raw_rcv(last, skb2);
	185	}
	186	last = sk;
	187	}
	188	}
	189
	190	if (last) {
	191	raw_rcv(last, skb);
	192	read_unlock(&ip_ra_lock);
	193	return 1;
	194	}
	195	read_unlock(&ip_ra_lock);
	196	return 0;
	197	}
	198
	199	static inline int ip_local_deliver_finish(struct sk_buff *skb)
	200	{
c9bdd4b5	201	__skb_pull(skb, ip_hdrlen(skb));
1da177e4	202
e905a9ed	203	/* Point into the IP datagram, just past the header. */
badff6d0	204	skb_reset_transport_header(skb);
1da177e4 LT	205
	206	rcu_read_lock();
	207	{
	208	/* Note: See raw.c and net/raw.h, RAWV4_HTABLE_SIZE==MAX_INET_PROTOS */
eddc9ec5	209	int protocol = ip_hdr(skb)->protocol;
1da177e4 LT	210	int hash;
	211	struct sock *raw_sk;
	212	struct net_protocol *ipprot;
	213
	214	resubmit:
	215	hash = protocol & (MAX_INET_PROTOS - 1);
	216	raw_sk = sk_head(&raw_v4_htable[hash]);
	217
	218	/* If there maybe a raw socket we must check - if not we
	219	* don't care less
	220	*/
eddc9ec5	221	if (raw_sk && !raw_v4_input(skb, ip_hdr(skb), hash))
d13964f4	222	raw_sk = NULL;
1da177e4 LT	223
	224	if ((ipprot = rcu_dereference(inet_protos[hash])) != NULL) {
	225	int ret;
	226
b59c2701 PM	227	if (!ipprot->no_policy) {
	228	if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
	229	kfree_skb(skb);
	230	goto out;
	231	}
	232	nf_reset(skb);
1da177e4 LT	233	}
	234	ret = ipprot->handler(skb);
	235	if (ret < 0) {
	236	protocol = -ret;
	237	goto resubmit;
	238	}
	239	IP_INC_STATS_BH(IPSTATS_MIB_INDELIVERS);
	240	} else {
	241	if (!raw_sk) {
	242	if (xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
	243	IP_INC_STATS_BH(IPSTATS_MIB_INUNKNOWNPROTOS);
	244	icmp_send(skb, ICMP_DEST_UNREACH,
	245	ICMP_PROT_UNREACH, 0);
	246	}
	247	} else
	248	IP_INC_STATS_BH(IPSTATS_MIB_INDELIVERS);
	249	kfree_skb(skb);
	250	}
	251	}
	252	out:
	253	rcu_read_unlock();
	254
	255	return 0;
	256	}
	257
	258	/*
	259	* Deliver IP Packets to the higher protocol layers.
e905a9ed	260	*/
1da177e4 LT	261	int ip_local_deliver(struct sk_buff *skb)
	262	{
	263	/*
	264	* Reassemble IP fragments.
	265	*/
	266
eddc9ec5	267	if (ip_hdr(skb)->frag_off & htons(IP_MF \| IP_OFFSET)) {
1da177e4 LT	268	skb = ip_defrag(skb, IP_DEFRAG_LOCAL_DELIVER);
	269	if (!skb)
	270	return 0;
	271	}
	272
	273	return NF_HOOK(PF_INET, NF_IP_LOCAL_IN, skb, skb->dev, NULL,
	274	ip_local_deliver_finish);
	275	}
	276
d245407e TG	277	static inline int ip_rcv_options(struct sk_buff *skb)
	278	{
	279	struct ip_options *opt;
	280	struct iphdr *iph;
	281	struct net_device *dev = skb->dev;
	282
	283	/* It looks as overkill, because not all
	284	IP options require packet mangling.
	285	But it is the easiest for now, especially taking
	286	into account that combination of IP options
	287	and running sniffer is extremely rare condition.
	288	--ANK (980813)
	289	*/
	290	if (skb_cow(skb, skb_headroom(skb))) {
	291	IP_INC_STATS_BH(IPSTATS_MIB_INDISCARDS);
	292	goto drop;
	293	}
	294
eddc9ec5	295	iph = ip_hdr(skb);
d245407e TG	296
	297	if (ip_options_compile(NULL, skb)) {
	298	IP_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
	299	goto drop;
	300	}
	301
	302	opt = &(IPCB(skb)->opt);
	303	if (unlikely(opt->srr)) {
	304	struct in_device *in_dev = in_dev_get(dev);
	305	if (in_dev) {
	306	if (!IN_DEV_SOURCE_ROUTE(in_dev)) {
	307	if (IN_DEV_LOG_MARTIANS(in_dev) &&
	308	net_ratelimit())
	309	printk(KERN_INFO "source route option "
	310	"%u.%u.%u.%u -> %u.%u.%u.%u\n",
	311	NIPQUAD(iph->saddr),
	312	NIPQUAD(iph->daddr));
	313	in_dev_put(in_dev);
	314	goto drop;
	315	}
	316
	317	in_dev_put(in_dev);
	318	}
	319
	320	if (ip_options_rcv_srr(skb))
	321	goto drop;
	322	}
	323
	324	return 0;
	325	drop:
	326	return -1;
	327	}
	328
1da177e4 LT	329	static inline int ip_rcv_finish(struct sk_buff *skb)
1da177e4 LT	330	{
eddc9ec5	331	const struct iphdr *iph = ip_hdr(skb);
5506b54b	332	struct rtable *rt;
1da177e4 LT	333
	334	/*
	335	* Initialise the virtual path cache for the packet. It describes
	336	* how the packet travels inside Linux networking.
e905a9ed	337	*/
0182bd2b	338	if (skb->dst == NULL) {
3e192bea TG	339	int err = ip_route_input(skb, iph->daddr, iph->saddr, iph->tos,
	340	skb->dev);
	341	if (unlikely(err)) {
2c2910a4 DE	342	if (err == -EHOSTUNREACH)
2c2910a4 DE	343	IP_INC_STATS_BH(IPSTATS_MIB_INADDRERRORS);
e91a47eb MC	344	else if (err == -ENETUNREACH)
e91a47eb MC	345	IP_INC_STATS_BH(IPSTATS_MIB_INNOROUTES);
e905a9ed	346	goto drop;
2c2910a4	347	}
1da177e4 LT	348	}
	349
	350	#ifdef CONFIG_NET_CLS_ROUTE
3e192bea	351	if (unlikely(skb->dst->tclassid)) {
1da177e4 LT	352	struct ip_rt_acct st = ip_rt_acct + 256smp_processor_id();
	353	u32 idx = skb->dst->tclassid;
	354	st[idx&0xFF].o_packets++;
	355	st[idx&0xFF].o_bytes+=skb->len;
	356	st[(idx>>16)&0xFF].i_packets++;
	357	st[(idx>>16)&0xFF].i_bytes+=skb->len;
	358	}
	359	#endif
	360
d245407e TG	361	if (iph->ihl > 5 && ip_rcv_options(skb))
d245407e TG	362	goto drop;
1da177e4	363
5506b54b MC	364	rt = (struct rtable*)skb->dst;
	365	if (rt->rt_type == RTN_MULTICAST)
	366	IP_INC_STATS_BH(IPSTATS_MIB_INMCASTPKTS);
	367	else if (rt->rt_type == RTN_BROADCAST)
	368	IP_INC_STATS_BH(IPSTATS_MIB_INBCASTPKTS);
	369
1da177e4 LT	370	return dst_input(skb);
1da177e4 LT	371
1da177e4	372	drop:
e905a9ed YH	373	kfree_skb(skb);
e905a9ed YH	374	return NET_RX_DROP;
1da177e4 LT	375	}
	376
	377	/*
	378	* Main IP Receive routine.
e905a9ed	379	*/
f2ccd8fa	380	int ip_rcv(struct sk_buff skb, struct net_device dev, struct packet_type pt, struct net_device orig_dev)
1da177e4 LT	381	{
1da177e4 LT	382	struct iphdr *iph;
58615242	383	u32 len;
1da177e4	384
e730c155 EB	385	if (dev->nd_net != &init_net)
	386	goto drop;
	387
1da177e4 LT	388	/* When the interface is in promisc. mode, drop all the crap
	389	* that it receives, do not try to analyse it.
	390	*/
	391	if (skb->pkt_type == PACKET_OTHERHOST)
	392	goto drop;
	393
	394	IP_INC_STATS_BH(IPSTATS_MIB_INRECEIVES);
	395
	396	if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL) {
	397	IP_INC_STATS_BH(IPSTATS_MIB_INDISCARDS);
	398	goto out;
	399	}
	400
	401	if (!pskb_may_pull(skb, sizeof(struct iphdr)))
	402	goto inhdr_error;
	403
eddc9ec5	404	iph = ip_hdr(skb);
1da177e4 LT	405
	406	/*
	407	* RFC1122: 3.1.2.2 MUST silently discard any IP frame that fails the checksum.
	408	*
	409	* Is the datagram acceptable?
	410	*
	411	* 1. Length at least the size of an ip header
	412	* 2. Version of 4
	413	* 3. Checksums correctly. [Speed optimisation for later, skip loopback checksums]
	414	* 4. Doesn't have a bogus length
	415	*/
	416
	417	if (iph->ihl < 5 \|\| iph->version != 4)
58615242	418	goto inhdr_error;
1da177e4 LT	419
	420	if (!pskb_may_pull(skb, iph->ihl*4))
	421	goto inhdr_error;
	422
eddc9ec5	423	iph = ip_hdr(skb);
1da177e4	424
e9c60422	425	if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
58615242	426	goto inhdr_error;
1da177e4	427
58615242	428	len = ntohs(iph->tot_len);
704aed53 MC	429	if (skb->len < len) {
	430	IP_INC_STATS_BH(IPSTATS_MIB_INTRUNCATEDPKTS);
	431	goto drop;
	432	} else if (len < (iph->ihl*4))
58615242	433	goto inhdr_error;
1da177e4	434
58615242 TG	435	/* Our transport medium may have padded the buffer out. Now we know it
	436	* is IP we can trim to the true length of the frame.
	437	* Note this now means skb->len holds ntohs(iph->tot_len).
	438	*/
	439	if (pskb_trim_rcsum(skb, len)) {
	440	IP_INC_STATS_BH(IPSTATS_MIB_INDISCARDS);
	441	goto drop;
1da177e4 LT	442	}
1da177e4 LT	443
53602f92	444	/* Remove any debris in the socket control block */
d569f1d7	445	memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
53602f92	446
1da177e4 LT	447	return NF_HOOK(PF_INET, NF_IP_PRE_ROUTING, skb, dev, NULL,
	448	ip_rcv_finish);
	449
	450	inhdr_error:
	451	IP_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
	452	drop:
e905a9ed	453	kfree_skb(skb);
1da177e4	454	out:
e905a9ed	455	return NET_RX_DROP;
1da177e4 LT	456	}
1da177e4 LT	457
1da177e4	458	EXPORT_SYMBOL(ip_statistics);