[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.
 *
 * 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;
	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(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(dev_net(dev), 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 "
					       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(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;

	/* 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: 3.2.1.2 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(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	*
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
	147	/*
	148	* SNMP management statistics
	149	*/
	150
ba89966c	151	DEFINE_SNMP_STAT(struct ipstats_mib, ip_statistics) __read_mostly;
1da177e4 LT	152
	153	/*
	154	* Process Router Attention IP option
e905a9ed	155	*/
1da177e4 LT	156	int ip_call_ra_chain(struct sk_buff *skb)
	157	{
	158	struct ip_ra_chain *ra;
eddc9ec5	159	u8 protocol = ip_hdr(skb)->protocol;
1da177e4	160	struct sock *last = NULL;
cb84663e	161	struct net_device *dev = skb->dev;
1da177e4 LT	162
	163	read_lock(&ip_ra_lock);
	164	for (ra = ip_ra_chain; ra; ra = ra->next) {
	165	struct sock *sk = ra->sk;
	166
	167	/* If socket is bound to an interface, only report
	168	* the packet if it came from that interface.
	169	*/
	170	if (sk && inet_sk(sk)->num == protocol &&
	171	(!sk->sk_bound_dev_if \|\|
cb84663e	172	sk->sk_bound_dev_if == dev->ifindex) &&
3b1e0a65	173	sock_net(sk) == dev_net(dev)) {
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	{
c346dca1	200	struct net *net = dev_net(skb->dev);
f145049a	201
c9bdd4b5	202	__skb_pull(skb, ip_hdrlen(skb));
1da177e4	203
e905a9ed	204	/* Point into the IP datagram, just past the header. */
badff6d0	205	skb_reset_transport_header(skb);
1da177e4 LT	206
	207	rcu_read_lock();
	208	{
eddc9ec5	209	int protocol = ip_hdr(skb)->protocol;
7bc54c90	210	int hash, raw;
1da177e4 LT	211	struct net_protocol *ipprot;
	212
	213	resubmit:
7bc54c90	214	raw = raw_local_deliver(skb, protocol);
1da177e4	215
7bc54c90	216	hash = protocol & (MAX_INET_PROTOS - 1);
f145049a DL	217	ipprot = rcu_dereference(inet_protos[hash]);
f145049a DL	218	if (ipprot != NULL && (net == &init_net \|\| ipprot->netns_ok)) {
1da177e4 LT	219	int ret;
1da177e4 LT	220
b59c2701 PM	221	if (!ipprot->no_policy) {
	222	if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
	223	kfree_skb(skb);
	224	goto out;
	225	}
	226	nf_reset(skb);
1da177e4 LT	227	}
	228	ret = ipprot->handler(skb);
	229	if (ret < 0) {
	230	protocol = -ret;
	231	goto resubmit;
	232	}
	233	IP_INC_STATS_BH(IPSTATS_MIB_INDELIVERS);
	234	} else {
7bc54c90	235	if (!raw) {
1da177e4 LT	236	if (xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
	237	IP_INC_STATS_BH(IPSTATS_MIB_INUNKNOWNPROTOS);
	238	icmp_send(skb, ICMP_DEST_UNREACH,
	239	ICMP_PROT_UNREACH, 0);
	240	}
	241	} else
	242	IP_INC_STATS_BH(IPSTATS_MIB_INDELIVERS);
	243	kfree_skb(skb);
	244	}
	245	}
	246	out:
	247	rcu_read_unlock();
	248
	249	return 0;
	250	}
	251
	252	/*
	253	* Deliver IP Packets to the higher protocol layers.
e905a9ed	254	*/
1da177e4 LT	255	int ip_local_deliver(struct sk_buff *skb)
	256	{
	257	/*
	258	* Reassemble IP fragments.
	259	*/
	260
eddc9ec5	261	if (ip_hdr(skb)->frag_off & htons(IP_MF \| IP_OFFSET)) {
776c729e	262	if (ip_defrag(skb, IP_DEFRAG_LOCAL_DELIVER))
1da177e4 LT	263	return 0;
	264	}
	265
6e23ae2a	266	return NF_HOOK(PF_INET, NF_INET_LOCAL_IN, skb, skb->dev, NULL,
1da177e4 LT	267	ip_local_deliver_finish);
	268	}
	269
d245407e TG	270	static inline int ip_rcv_options(struct sk_buff *skb)
	271	{
	272	struct ip_options *opt;
	273	struct iphdr *iph;
	274	struct net_device *dev = skb->dev;
	275
	276	/* It looks as overkill, because not all
	277	IP options require packet mangling.
	278	But it is the easiest for now, especially taking
	279	into account that combination of IP options
	280	and running sniffer is extremely rare condition.
	281	--ANK (980813)
	282	*/
	283	if (skb_cow(skb, skb_headroom(skb))) {
	284	IP_INC_STATS_BH(IPSTATS_MIB_INDISCARDS);
	285	goto drop;
	286	}
	287
eddc9ec5	288	iph = ip_hdr(skb);
22aba383 DL	289	opt = &(IPCB(skb)->opt);
22aba383 DL	290	opt->optlen = iph->ihl*4 - sizeof(struct iphdr);
d245407e	291
c346dca1	292	if (ip_options_compile(dev_net(dev), opt, skb)) {
d245407e TG	293	IP_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
	294	goto drop;
	295	}
	296
d245407e TG	297	if (unlikely(opt->srr)) {
	298	struct in_device *in_dev = in_dev_get(dev);
	299	if (in_dev) {
	300	if (!IN_DEV_SOURCE_ROUTE(in_dev)) {
	301	if (IN_DEV_LOG_MARTIANS(in_dev) &&
	302	net_ratelimit())
	303	printk(KERN_INFO "source route option "
a7d632b6	304	NIPQUAD_FMT " -> " NIPQUAD_FMT "\n",
d245407e TG	305	NIPQUAD(iph->saddr),
	306	NIPQUAD(iph->daddr));
	307	in_dev_put(in_dev);
	308	goto drop;
	309	}
	310
	311	in_dev_put(in_dev);
	312	}
	313
	314	if (ip_options_rcv_srr(skb))
	315	goto drop;
	316	}
	317
	318	return 0;
	319	drop:
	320	return -1;
	321	}
	322
861d0486	323	static int ip_rcv_finish(struct sk_buff *skb)
1da177e4	324	{
eddc9ec5	325	const struct iphdr *iph = ip_hdr(skb);
5506b54b	326	struct rtable *rt;
1da177e4 LT	327
	328	/*
	329	* Initialise the virtual path cache for the packet. It describes
	330	* how the packet travels inside Linux networking.
e905a9ed	331	*/
0182bd2b	332	if (skb->dst == NULL) {
3e192bea TG	333	int err = ip_route_input(skb, iph->daddr, iph->saddr, iph->tos,
	334	skb->dev);
	335	if (unlikely(err)) {
2c2910a4 DE	336	if (err == -EHOSTUNREACH)
2c2910a4 DE	337	IP_INC_STATS_BH(IPSTATS_MIB_INADDRERRORS);
e91a47eb MC	338	else if (err == -ENETUNREACH)
e91a47eb MC	339	IP_INC_STATS_BH(IPSTATS_MIB_INNOROUTES);
e905a9ed	340	goto drop;
2c2910a4	341	}
1da177e4 LT	342	}
	343
	344	#ifdef CONFIG_NET_CLS_ROUTE
3e192bea	345	if (unlikely(skb->dst->tclassid)) {
8dbde28d	346	struct ip_rt_acct *st = per_cpu_ptr(ip_rt_acct, smp_processor_id());
1da177e4 LT	347	u32 idx = skb->dst->tclassid;
	348	st[idx&0xFF].o_packets++;
	349	st[idx&0xFF].o_bytes+=skb->len;
	350	st[(idx>>16)&0xFF].i_packets++;
	351	st[(idx>>16)&0xFF].i_bytes+=skb->len;
	352	}
	353	#endif
	354
d245407e TG	355	if (iph->ihl > 5 && ip_rcv_options(skb))
d245407e TG	356	goto drop;
1da177e4	357
ee6b9673	358	rt = skb->rtable;
5506b54b MC	359	if (rt->rt_type == RTN_MULTICAST)
	360	IP_INC_STATS_BH(IPSTATS_MIB_INMCASTPKTS);
	361	else if (rt->rt_type == RTN_BROADCAST)
	362	IP_INC_STATS_BH(IPSTATS_MIB_INBCASTPKTS);
	363
1da177e4 LT	364	return dst_input(skb);
1da177e4 LT	365
1da177e4	366	drop:
e905a9ed YH	367	kfree_skb(skb);
e905a9ed YH	368	return NET_RX_DROP;
1da177e4 LT	369	}
	370
	371	/*
	372	* Main IP Receive routine.
e905a9ed	373	*/
f2ccd8fa	374	int ip_rcv(struct sk_buff skb, struct net_device dev, struct packet_type pt, struct net_device orig_dev)
1da177e4 LT	375	{
1da177e4 LT	376	struct iphdr *iph;
58615242	377	u32 len;
1da177e4 LT	378
	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
1da177e4 LT	397	/*
c67fa027	398	* RFC1122: 3.2.1.2 MUST silently discard any IP frame that fails the checksum.
1da177e4 LT	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);