[deliverable/linux.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)) {
				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)
{
	__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;
		struct net_protocol *ipprot;

	resubmit:
		raw = raw_local_deliver(skb, protocol);

		hash = protocol & (MAX_INET_PROTOS - 1);
		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) {
				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)) {
		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(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(opt, skb)) {
		IP_INC_STATS_BH(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 "
					       "%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 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 = per_cpu_ptr(ip_rt_acct, 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 = skb->rtable;
	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_INET_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)) {
776c729e	175	if (ip_defrag(skb, IP_DEFRAG_CALL_RA_CHAIN)) {
1da177e4 LT	176	read_unlock(&ip_ra_lock);
	177	return 1;
	178	}
	179	}
	180	if (last) {
	181	struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
	182	if (skb2)
	183	raw_rcv(last, skb2);
	184	}
	185	last = sk;
	186	}
	187	}
	188
	189	if (last) {
	190	raw_rcv(last, skb);
	191	read_unlock(&ip_ra_lock);
	192	return 1;
	193	}
	194	read_unlock(&ip_ra_lock);
	195	return 0;
	196	}
	197
861d0486	198	static int ip_local_deliver_finish(struct sk_buff *skb)
1da177e4	199	{
c9bdd4b5	200	__skb_pull(skb, ip_hdrlen(skb));
1da177e4	201
e905a9ed	202	/* Point into the IP datagram, just past the header. */
badff6d0	203	skb_reset_transport_header(skb);
1da177e4 LT	204
	205	rcu_read_lock();
	206	{
eddc9ec5	207	int protocol = ip_hdr(skb)->protocol;
7bc54c90	208	int hash, raw;
1da177e4 LT	209	struct net_protocol *ipprot;
	210
	211	resubmit:
7bc54c90	212	raw = raw_local_deliver(skb, protocol);
1da177e4	213
7bc54c90	214	hash = protocol & (MAX_INET_PROTOS - 1);
1da177e4 LT	215	if ((ipprot = rcu_dereference(inet_protos[hash])) != NULL) {
	216	int ret;
	217
b59c2701 PM	218	if (!ipprot->no_policy) {
	219	if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
	220	kfree_skb(skb);
	221	goto out;
	222	}
	223	nf_reset(skb);
1da177e4 LT	224	}
	225	ret = ipprot->handler(skb);
	226	if (ret < 0) {
	227	protocol = -ret;
	228	goto resubmit;
	229	}
	230	IP_INC_STATS_BH(IPSTATS_MIB_INDELIVERS);
	231	} else {
7bc54c90	232	if (!raw) {
1da177e4 LT	233	if (xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
	234	IP_INC_STATS_BH(IPSTATS_MIB_INUNKNOWNPROTOS);
	235	icmp_send(skb, ICMP_DEST_UNREACH,
	236	ICMP_PROT_UNREACH, 0);
	237	}
	238	} else
	239	IP_INC_STATS_BH(IPSTATS_MIB_INDELIVERS);
	240	kfree_skb(skb);
	241	}
	242	}
	243	out:
	244	rcu_read_unlock();
	245
	246	return 0;
	247	}
	248
	249	/*
	250	* Deliver IP Packets to the higher protocol layers.
e905a9ed	251	*/
1da177e4 LT	252	int ip_local_deliver(struct sk_buff *skb)
	253	{
	254	/*
	255	* Reassemble IP fragments.
	256	*/
	257
eddc9ec5	258	if (ip_hdr(skb)->frag_off & htons(IP_MF \| IP_OFFSET)) {
776c729e	259	if (ip_defrag(skb, IP_DEFRAG_LOCAL_DELIVER))
1da177e4 LT	260	return 0;
	261	}
	262
6e23ae2a	263	return NF_HOOK(PF_INET, NF_INET_LOCAL_IN, skb, skb->dev, NULL,
1da177e4 LT	264	ip_local_deliver_finish);
	265	}
	266
d245407e TG	267	static inline int ip_rcv_options(struct sk_buff *skb)
	268	{
	269	struct ip_options *opt;
	270	struct iphdr *iph;
	271	struct net_device *dev = skb->dev;
	272
	273	/* It looks as overkill, because not all
	274	IP options require packet mangling.
	275	But it is the easiest for now, especially taking
	276	into account that combination of IP options
	277	and running sniffer is extremely rare condition.
	278	--ANK (980813)
	279	*/
	280	if (skb_cow(skb, skb_headroom(skb))) {
	281	IP_INC_STATS_BH(IPSTATS_MIB_INDISCARDS);
	282	goto drop;
	283	}
	284
eddc9ec5	285	iph = ip_hdr(skb);
22aba383 DL	286	opt = &(IPCB(skb)->opt);
22aba383 DL	287	opt->optlen = iph->ihl*4 - sizeof(struct iphdr);
d245407e	288
22aba383	289	if (ip_options_compile(opt, skb)) {
d245407e TG	290	IP_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
	291	goto drop;
	292	}
	293
d245407e TG	294	if (unlikely(opt->srr)) {
	295	struct in_device *in_dev = in_dev_get(dev);
	296	if (in_dev) {
	297	if (!IN_DEV_SOURCE_ROUTE(in_dev)) {
	298	if (IN_DEV_LOG_MARTIANS(in_dev) &&
	299	net_ratelimit())
	300	printk(KERN_INFO "source route option "
	301	"%u.%u.%u.%u -> %u.%u.%u.%u\n",
	302	NIPQUAD(iph->saddr),
	303	NIPQUAD(iph->daddr));
	304	in_dev_put(in_dev);
	305	goto drop;
	306	}
	307
	308	in_dev_put(in_dev);
	309	}
	310
	311	if (ip_options_rcv_srr(skb))
	312	goto drop;
	313	}
	314
	315	return 0;
	316	drop:
	317	return -1;
	318	}
	319
861d0486	320	static int ip_rcv_finish(struct sk_buff *skb)
1da177e4	321	{
eddc9ec5	322	const struct iphdr *iph = ip_hdr(skb);
5506b54b	323	struct rtable *rt;
1da177e4 LT	324
	325	/*
	326	* Initialise the virtual path cache for the packet. It describes
	327	* how the packet travels inside Linux networking.
e905a9ed	328	*/
0182bd2b	329	if (skb->dst == NULL) {
3e192bea TG	330	int err = ip_route_input(skb, iph->daddr, iph->saddr, iph->tos,
	331	skb->dev);
	332	if (unlikely(err)) {
2c2910a4 DE	333	if (err == -EHOSTUNREACH)
2c2910a4 DE	334	IP_INC_STATS_BH(IPSTATS_MIB_INADDRERRORS);
e91a47eb MC	335	else if (err == -ENETUNREACH)
e91a47eb MC	336	IP_INC_STATS_BH(IPSTATS_MIB_INNOROUTES);
e905a9ed	337	goto drop;
2c2910a4	338	}
1da177e4 LT	339	}
	340
	341	#ifdef CONFIG_NET_CLS_ROUTE
3e192bea	342	if (unlikely(skb->dst->tclassid)) {
8dbde28d	343	struct ip_rt_acct *st = per_cpu_ptr(ip_rt_acct, smp_processor_id());
1da177e4 LT	344	u32 idx = skb->dst->tclassid;
	345	st[idx&0xFF].o_packets++;
	346	st[idx&0xFF].o_bytes+=skb->len;
	347	st[(idx>>16)&0xFF].i_packets++;
	348	st[(idx>>16)&0xFF].i_bytes+=skb->len;
	349	}
	350	#endif
	351
d245407e TG	352	if (iph->ihl > 5 && ip_rcv_options(skb))
d245407e TG	353	goto drop;
1da177e4	354
ee6b9673	355	rt = skb->rtable;
5506b54b MC	356	if (rt->rt_type == RTN_MULTICAST)
	357	IP_INC_STATS_BH(IPSTATS_MIB_INMCASTPKTS);
	358	else if (rt->rt_type == RTN_BROADCAST)
	359	IP_INC_STATS_BH(IPSTATS_MIB_INBCASTPKTS);
	360
1da177e4 LT	361	return dst_input(skb);
1da177e4 LT	362
1da177e4	363	drop:
e905a9ed YH	364	kfree_skb(skb);
e905a9ed YH	365	return NET_RX_DROP;
1da177e4 LT	366	}
	367
	368	/*
	369	* Main IP Receive routine.
e905a9ed	370	*/
f2ccd8fa	371	int ip_rcv(struct sk_buff skb, struct net_device dev, struct packet_type pt, struct net_device orig_dev)
1da177e4 LT	372	{
1da177e4 LT	373	struct iphdr *iph;
58615242	374	u32 len;
1da177e4	375
e730c155 EB	376	if (dev->nd_net != &init_net)
	377	goto drop;
	378
1da177e4 LT	379	/* When the interface is in promisc. mode, drop all the crap
	380	* that it receives, do not try to analyse it.
	381	*/
	382	if (skb->pkt_type == PACKET_OTHERHOST)
	383	goto drop;
	384
	385	IP_INC_STATS_BH(IPSTATS_MIB_INRECEIVES);
	386
	387	if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL) {
	388	IP_INC_STATS_BH(IPSTATS_MIB_INDISCARDS);
	389	goto out;
	390	}
	391
	392	if (!pskb_may_pull(skb, sizeof(struct iphdr)))
	393	goto inhdr_error;
	394
eddc9ec5	395	iph = ip_hdr(skb);
1da177e4 LT	396
	397	/*
	398	* RFC1122: 3.1.2.2 MUST silently discard any IP frame that fails the checksum.
	399	*
	400	* Is the datagram acceptable?
	401	*
	402	* 1. Length at least the size of an ip header
	403	* 2. Version of 4
	404	* 3. Checksums correctly. [Speed optimisation for later, skip loopback checksums]
	405	* 4. Doesn't have a bogus length
	406	*/
	407
	408	if (iph->ihl < 5 \|\| iph->version != 4)
58615242	409	goto inhdr_error;
1da177e4 LT	410
	411	if (!pskb_may_pull(skb, iph->ihl*4))
	412	goto inhdr_error;
	413
eddc9ec5	414	iph = ip_hdr(skb);
1da177e4	415
e9c60422	416	if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
58615242	417	goto inhdr_error;
1da177e4	418
58615242	419	len = ntohs(iph->tot_len);
704aed53 MC	420	if (skb->len < len) {
	421	IP_INC_STATS_BH(IPSTATS_MIB_INTRUNCATEDPKTS);
	422	goto drop;
	423	} else if (len < (iph->ihl*4))
58615242	424	goto inhdr_error;
1da177e4	425
58615242 TG	426	/* Our transport medium may have padded the buffer out. Now we know it
	427	* is IP we can trim to the true length of the frame.
	428	* Note this now means skb->len holds ntohs(iph->tot_len).
	429	*/
	430	if (pskb_trim_rcsum(skb, len)) {
	431	IP_INC_STATS_BH(IPSTATS_MIB_INDISCARDS);
	432	goto drop;
1da177e4 LT	433	}
1da177e4 LT	434
53602f92	435	/* Remove any debris in the socket control block */
d569f1d7	436	memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
53602f92	437
6e23ae2a	438	return NF_HOOK(PF_INET, NF_INET_PRE_ROUTING, skb, dev, NULL,
1da177e4 LT	439	ip_rcv_finish);
	440
	441	inhdr_error:
	442	IP_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
	443	drop:
e905a9ed	444	kfree_skb(skb);
1da177e4	445	out:
e905a9ed	446	return NET_RX_DROP;
1da177e4 LT	447	}
1da177e4 LT	448
1da177e4	449	EXPORT_SYMBOL(ip_statistics);