[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.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>

/*
 *	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)->num == protocol &&
		    (!sk->sk_bound_dev_if ||
		     sk->sk_bound_dev_if == dev->ifindex) &&
		    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;
		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 && (net == &init_net || ipprot->netns_ok)) {
			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(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 "
					       NIPQUAD_FMT " -> " NIPQUAD_FMT "\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(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->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(dev_net(rt->u.dst.dev), IPSTATS_MIB_INMCASTPKTS);
	else if (rt->rt_type == RTN_BROADCAST)
		IP_INC_STATS_BH(dev_net(rt->u.dst.dev), 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;

	/* 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(dev_net(dev), IPSTATS_MIB_INRECEIVES);

	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));

	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>
	10	* Donald Becker, <becker@super.org>
	11	* Alan Cox, <Alan.Cox@linux.org>
	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>
1da177e4 LT	122
	123	#include <linux/net.h>
	124	#include <linux/socket.h>
	125	#include <linux/sockios.h>
	126	#include <linux/in.h>
	127	#include <linux/inet.h>
14c85021	128	#include <linux/inetdevice.h>
1da177e4 LT	129	#include <linux/netdevice.h>
	130	#include <linux/etherdevice.h>
	131
	132	#include <net/snmp.h>
	133	#include <net/ip.h>
	134	#include <net/protocol.h>
	135	#include <net/route.h>
	136	#include <linux/skbuff.h>
	137	#include <net/sock.h>
	138	#include <net/arp.h>
	139	#include <net/icmp.h>
	140	#include <net/raw.h>
	141	#include <net/checksum.h>
	142	#include <linux/netfilter_ipv4.h>
	143	#include <net/xfrm.h>
	144	#include <linux/mroute.h>
	145	#include <linux/netlink.h>
	146
1da177e4 LT	147	/*
1da177e4 LT	148	* Process Router Attention IP option
e905a9ed	149	*/
1da177e4 LT	150	int ip_call_ra_chain(struct sk_buff *skb)
	151	{
	152	struct ip_ra_chain *ra;
eddc9ec5	153	u8 protocol = ip_hdr(skb)->protocol;
1da177e4	154	struct sock *last = NULL;
cb84663e	155	struct net_device *dev = skb->dev;
1da177e4 LT	156
	157	read_lock(&ip_ra_lock);
	158	for (ra = ip_ra_chain; ra; ra = ra->next) {
	159	struct sock *sk = ra->sk;
	160
	161	/* If socket is bound to an interface, only report
	162	* the packet if it came from that interface.
	163	*/
	164	if (sk && inet_sk(sk)->num == protocol &&
	165	(!sk->sk_bound_dev_if \|\|
cb84663e	166	sk->sk_bound_dev_if == dev->ifindex) &&
3b1e0a65	167	sock_net(sk) == dev_net(dev)) {
eddc9ec5	168	if (ip_hdr(skb)->frag_off & htons(IP_MF \| IP_OFFSET)) {
776c729e	169	if (ip_defrag(skb, IP_DEFRAG_CALL_RA_CHAIN)) {
1da177e4 LT	170	read_unlock(&ip_ra_lock);
	171	return 1;
	172	}
	173	}
	174	if (last) {
	175	struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
	176	if (skb2)
	177	raw_rcv(last, skb2);
	178	}
	179	last = sk;
	180	}
	181	}
	182
	183	if (last) {
	184	raw_rcv(last, skb);
	185	read_unlock(&ip_ra_lock);
	186	return 1;
	187	}
	188	read_unlock(&ip_ra_lock);
	189	return 0;
	190	}
	191
861d0486	192	static int ip_local_deliver_finish(struct sk_buff *skb)
1da177e4	193	{
c346dca1	194	struct net *net = dev_net(skb->dev);
f145049a	195
c9bdd4b5	196	__skb_pull(skb, ip_hdrlen(skb));
1da177e4	197
e905a9ed	198	/* Point into the IP datagram, just past the header. */
badff6d0	199	skb_reset_transport_header(skb);
1da177e4 LT	200
	201	rcu_read_lock();
	202	{
eddc9ec5	203	int protocol = ip_hdr(skb)->protocol;
7bc54c90	204	int hash, raw;
1da177e4 LT	205	struct net_protocol *ipprot;
	206
	207	resubmit:
7bc54c90	208	raw = raw_local_deliver(skb, protocol);
1da177e4	209
7bc54c90	210	hash = protocol & (MAX_INET_PROTOS - 1);
f145049a DL	211	ipprot = rcu_dereference(inet_protos[hash]);
f145049a DL	212	if (ipprot != NULL && (net == &init_net \|\| ipprot->netns_ok)) {
1da177e4 LT	213	int ret;
1da177e4 LT	214
b59c2701 PM	215	if (!ipprot->no_policy) {
	216	if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
	217	kfree_skb(skb);
	218	goto out;
	219	}
	220	nf_reset(skb);
1da177e4 LT	221	}
	222	ret = ipprot->handler(skb);
	223	if (ret < 0) {
	224	protocol = -ret;
	225	goto resubmit;
	226	}
7c73a6fa	227	IP_INC_STATS_BH(net, IPSTATS_MIB_INDELIVERS);
1da177e4	228	} else {
7bc54c90	229	if (!raw) {
1da177e4	230	if (xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
7c73a6fa	231	IP_INC_STATS_BH(net, IPSTATS_MIB_INUNKNOWNPROTOS);
1da177e4 LT	232	icmp_send(skb, ICMP_DEST_UNREACH,
	233	ICMP_PROT_UNREACH, 0);
	234	}
	235	} else
7c73a6fa	236	IP_INC_STATS_BH(net, IPSTATS_MIB_INDELIVERS);
1da177e4 LT	237	kfree_skb(skb);
	238	}
	239	}
	240	out:
	241	rcu_read_unlock();
	242
	243	return 0;
	244	}
	245
	246	/*
	247	* Deliver IP Packets to the higher protocol layers.
e905a9ed	248	*/
1da177e4 LT	249	int ip_local_deliver(struct sk_buff *skb)
	250	{
	251	/*
	252	* Reassemble IP fragments.
	253	*/
	254
eddc9ec5	255	if (ip_hdr(skb)->frag_off & htons(IP_MF \| IP_OFFSET)) {
776c729e	256	if (ip_defrag(skb, IP_DEFRAG_LOCAL_DELIVER))
1da177e4 LT	257	return 0;
	258	}
	259
6e23ae2a	260	return NF_HOOK(PF_INET, NF_INET_LOCAL_IN, skb, skb->dev, NULL,
1da177e4 LT	261	ip_local_deliver_finish);
	262	}
	263
d245407e TG	264	static inline int ip_rcv_options(struct sk_buff *skb)
	265	{
	266	struct ip_options *opt;
	267	struct iphdr *iph;
	268	struct net_device *dev = skb->dev;
	269
	270	/* It looks as overkill, because not all
	271	IP options require packet mangling.
	272	But it is the easiest for now, especially taking
	273	into account that combination of IP options
	274	and running sniffer is extremely rare condition.
	275	--ANK (980813)
	276	*/
	277	if (skb_cow(skb, skb_headroom(skb))) {
7c73a6fa	278	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
d245407e TG	279	goto drop;
	280	}
	281
eddc9ec5	282	iph = ip_hdr(skb);
22aba383 DL	283	opt = &(IPCB(skb)->opt);
22aba383 DL	284	opt->optlen = iph->ihl*4 - sizeof(struct iphdr);
d245407e	285
c346dca1	286	if (ip_options_compile(dev_net(dev), opt, skb)) {
7c73a6fa	287	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INHDRERRORS);
d245407e TG	288	goto drop;
	289	}
	290
d245407e TG	291	if (unlikely(opt->srr)) {
	292	struct in_device *in_dev = in_dev_get(dev);
	293	if (in_dev) {
	294	if (!IN_DEV_SOURCE_ROUTE(in_dev)) {
	295	if (IN_DEV_LOG_MARTIANS(in_dev) &&
	296	net_ratelimit())
	297	printk(KERN_INFO "source route option "
a7d632b6	298	NIPQUAD_FMT " -> " NIPQUAD_FMT "\n",
d245407e TG	299	NIPQUAD(iph->saddr),
	300	NIPQUAD(iph->daddr));
	301	in_dev_put(in_dev);
	302	goto drop;
	303	}
	304
	305	in_dev_put(in_dev);
	306	}
	307
	308	if (ip_options_rcv_srr(skb))
	309	goto drop;
	310	}
	311
	312	return 0;
	313	drop:
	314	return -1;
	315	}
	316
861d0486	317	static int ip_rcv_finish(struct sk_buff *skb)
1da177e4	318	{
eddc9ec5	319	const struct iphdr *iph = ip_hdr(skb);
5506b54b	320	struct rtable *rt;
1da177e4 LT	321
	322	/*
	323	* Initialise the virtual path cache for the packet. It describes
	324	* how the packet travels inside Linux networking.
e905a9ed	325	*/
0182bd2b	326	if (skb->dst == NULL) {
3e192bea TG	327	int err = ip_route_input(skb, iph->daddr, iph->saddr, iph->tos,
	328	skb->dev);
	329	if (unlikely(err)) {
2c2910a4	330	if (err == -EHOSTUNREACH)
7c73a6fa PE	331	IP_INC_STATS_BH(dev_net(skb->dev),
7c73a6fa PE	332	IPSTATS_MIB_INADDRERRORS);
e91a47eb	333	else if (err == -ENETUNREACH)
7c73a6fa PE	334	IP_INC_STATS_BH(dev_net(skb->dev),
7c73a6fa PE	335	IPSTATS_MIB_INNOROUTES);
e905a9ed	336	goto drop;
2c2910a4	337	}
1da177e4 LT	338	}
	339
	340	#ifdef CONFIG_NET_CLS_ROUTE
3e192bea	341	if (unlikely(skb->dst->tclassid)) {
8dbde28d	342	struct ip_rt_acct *st = per_cpu_ptr(ip_rt_acct, smp_processor_id());
1da177e4 LT	343	u32 idx = skb->dst->tclassid;
	344	st[idx&0xFF].o_packets++;
	345	st[idx&0xFF].o_bytes+=skb->len;
	346	st[(idx>>16)&0xFF].i_packets++;
	347	st[(idx>>16)&0xFF].i_bytes+=skb->len;
	348	}
	349	#endif
	350
d245407e TG	351	if (iph->ihl > 5 && ip_rcv_options(skb))
d245407e TG	352	goto drop;
1da177e4	353
ee6b9673	354	rt = skb->rtable;
5506b54b	355	if (rt->rt_type == RTN_MULTICAST)
7c73a6fa	356	IP_INC_STATS_BH(dev_net(rt->u.dst.dev), IPSTATS_MIB_INMCASTPKTS);
5506b54b	357	else if (rt->rt_type == RTN_BROADCAST)
7c73a6fa	358	IP_INC_STATS_BH(dev_net(rt->u.dst.dev), IPSTATS_MIB_INBCASTPKTS);
5506b54b	359
1da177e4 LT	360	return dst_input(skb);
1da177e4 LT	361
1da177e4	362	drop:
e905a9ed YH	363	kfree_skb(skb);
e905a9ed YH	364	return NET_RX_DROP;
1da177e4 LT	365	}
	366
	367	/*
	368	* Main IP Receive routine.
e905a9ed	369	*/
f2ccd8fa	370	int ip_rcv(struct sk_buff skb, struct net_device dev, struct packet_type pt, struct net_device orig_dev)
1da177e4 LT	371	{
1da177e4 LT	372	struct iphdr *iph;
58615242	373	u32 len;
1da177e4 LT	374
	375	/* When the interface is in promisc. mode, drop all the crap
	376	* that it receives, do not try to analyse it.
	377	*/
	378	if (skb->pkt_type == PACKET_OTHERHOST)
	379	goto drop;
	380
7c73a6fa	381	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INRECEIVES);
1da177e4 LT	382
1da177e4 LT	383	if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL) {
7c73a6fa	384	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
1da177e4 LT	385	goto out;
	386	}
	387
	388	if (!pskb_may_pull(skb, sizeof(struct iphdr)))
	389	goto inhdr_error;
	390
eddc9ec5	391	iph = ip_hdr(skb);
1da177e4 LT	392
1da177e4 LT	393	/*
c67fa027	394	* RFC1122: 3.2.1.2 MUST silently discard any IP frame that fails the checksum.
1da177e4 LT	395	*
	396	* Is the datagram acceptable?
	397	*
	398	* 1. Length at least the size of an ip header
	399	* 2. Version of 4
	400	* 3. Checksums correctly. [Speed optimisation for later, skip loopback checksums]
	401	* 4. Doesn't have a bogus length
	402	*/
	403
	404	if (iph->ihl < 5 \|\| iph->version != 4)
58615242	405	goto inhdr_error;
1da177e4 LT	406
	407	if (!pskb_may_pull(skb, iph->ihl*4))
	408	goto inhdr_error;
	409
eddc9ec5	410	iph = ip_hdr(skb);
1da177e4	411
e9c60422	412	if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
58615242	413	goto inhdr_error;
1da177e4	414
58615242	415	len = ntohs(iph->tot_len);
704aed53	416	if (skb->len < len) {
7c73a6fa	417	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INTRUNCATEDPKTS);
704aed53 MC	418	goto drop;
704aed53 MC	419	} else if (len < (iph->ihl*4))
58615242	420	goto inhdr_error;
1da177e4	421
58615242 TG	422	/* Our transport medium may have padded the buffer out. Now we know it
	423	* is IP we can trim to the true length of the frame.
	424	* Note this now means skb->len holds ntohs(iph->tot_len).
	425	*/
	426	if (pskb_trim_rcsum(skb, len)) {
7c73a6fa	427	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
58615242	428	goto drop;
1da177e4 LT	429	}
1da177e4 LT	430
53602f92	431	/* Remove any debris in the socket control block */
d569f1d7	432	memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
53602f92	433
6e23ae2a	434	return NF_HOOK(PF_INET, NF_INET_PRE_ROUTING, skb, dev, NULL,
1da177e4 LT	435	ip_rcv_finish);
	436
	437	inhdr_error:
7c73a6fa	438	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INHDRERRORS);
1da177e4	439	drop:
e905a9ed	440	kfree_skb(skb);
1da177e4	441	out:
e905a9ed	442	return NET_RX_DROP;
1da177e4	443	}