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

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

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

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

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

/*
 *	Process Router Attention IP option (RFC 2113)
 */
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;

	for (ra = rcu_dereference(ip_ra_chain); ra; ra = rcu_dereference(ra->next)) {
		struct sock *sk = ra->sk;

		/* If socket is bound to an interface, only report
		 * the packet if it came  from that interface.
		 */
		if (sk && inet_sk(sk)->inet_num == protocol &&
		    (!sk->sk_bound_dev_if ||
		     sk->sk_bound_dev_if == dev->ifindex) &&
		    net_eq(sock_net(sk), dev_net(dev))) {
			if (ip_hdr(skb)->frag_off & htons(IP_MF | IP_OFFSET)) {
				if (ip_defrag(skb, IP_DEFRAG_CALL_RA_CHAIN))
					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);
		return 1;
	}
	return 0;
}

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

	__skb_pull(skb, ip_hdrlen(skb));

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

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

	resubmit:
		raw = raw_local_deliver(skb, protocol);

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

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

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

	return 0;
}

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

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

	return NF_HOOK(NFPROTO_IPV4, 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_rcu(dev);

		if (in_dev) {
			if (!IN_DEV_SOURCE_ROUTE(in_dev)) {
				if (IN_DEV_LOG_MARTIANS(in_dev) &&
				    net_ratelimit())
					printk(KERN_INFO "source route option %pI4 -> %pI4\n",
					       &iph->saddr, &iph->daddr);
				goto drop;
			}
		}

		if (ip_options_rcv_srr(skb))
			goto drop;
	}

	return 0;
drop:
	return -1;
}

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

	/*
	 *	Initialise the virtual path cache for the packet. It describes
	 *	how the packet travels inside Linux networking.
	 */
	if (skb_dst(skb) == NULL) {
		int err = ip_route_input_noref(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);
			else if (err == -EXDEV)
				NET_INC_STATS_BH(dev_net(skb->dev),
						 LINUX_MIB_IPRPFILTER);
			goto drop;
		}
	}

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

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

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

	return dst_input(skb);

drop:
	kfree_skb(skb);
	return NET_RX_DROP;
}

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

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


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

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

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

	iph = ip_hdr(skb);

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

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

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

	iph = ip_hdr(skb);

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

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

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

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

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

	return NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, skb, dev, NULL,
		       ip_rcv_finish);

inhdr_error:
	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INHDRERRORS);
drop:
	kfree_skb(skb);
out:
	return NET_RX_DROP;
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* INET An implementation of the TCP/IP protocol suite for the LINUX
	3	* operating system. INET is implemented using the BSD Socket
	4	* interface as the means of communication with the user level.
	5	*
	6	* The Internet Protocol (IP) module.
	7	*
02c30a84	8	* Authors: Ross Biro
1da177e4 LT	9	* Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
1da177e4 LT	10	* Donald Becker, <becker@super.org>
113aa838	11	* Alan Cox, <alan@lxorguk.ukuu.org.uk>
1da177e4 LT	12	* Richard Underwood
	13	* Stefan Becker, <stefanb@yello.ping.de>
	14	* Jorge Cwik, <jorge@laser.satlink.net>
	15	* Arnt Gulbrandsen, <agulbra@nvg.unit.no>
e905a9ed	16	*
1da177e4 LT	17	*
	18	* Fixes:
	19	* Alan Cox : Commented a couple of minor bits of surplus code
	20	* Alan Cox : Undefining IP_FORWARD doesn't include the code
	21	* (just stops a compiler warning).
	22	* Alan Cox : Frames with >=MAX_ROUTE record routes, strict routes or loose routes
	23	* are junked rather than corrupting things.
	24	* Alan Cox : Frames to bad broadcast subnets are dumped
	25	* We used to process them non broadcast and
	26	* boy could that cause havoc.
	27	* Alan Cox : ip_forward sets the free flag on the
	28	* new frame it queues. Still crap because
	29	* it copies the frame but at least it
	30	* doesn't eat memory too.
	31	* Alan Cox : Generic queue code and memory fixes.
	32	* Fred Van Kempen : IP fragment support (borrowed from NET2E)
	33	* Gerhard Koerting: Forward fragmented frames correctly.
	34	* Gerhard Koerting: Fixes to my fix of the above 8-).
	35	* Gerhard Koerting: IP interface addressing fix.
	36	* Linus Torvalds : More robustness checks
	37	* Alan Cox : Even more checks: Still not as robust as it ought to be
	38	* Alan Cox : Save IP header pointer for later
	39	* Alan Cox : ip option setting
	40	* Alan Cox : Use ip_tos/ip_ttl settings
	41	* Alan Cox : Fragmentation bogosity removed
	42	* (Thanks to Mark.Bush@prg.ox.ac.uk)
	43	* Dmitry Gorodchanin : Send of a raw packet crash fix.
	44	* Alan Cox : Silly ip bug when an overlength
	45	* fragment turns up. Now frees the
	46	* queue.
	47	* Linus Torvalds/ : Memory leakage on fragmentation
	48	* Alan Cox : handling.
	49	* Gerhard Koerting: Forwarding uses IP priority hints
	50	* Teemu Rantanen : Fragment problems.
	51	* Alan Cox : General cleanup, comments and reformat
	52	* Alan Cox : SNMP statistics
	53	* Alan Cox : BSD address rule semantics. Also see
	54	* UDP as there is a nasty checksum issue
	55	* if you do things the wrong way.
	56	* Alan Cox : Always defrag, moved IP_FORWARD to the config.in file
	57	* Alan Cox : IP options adjust sk->priority.
	58	* Pedro Roque : Fix mtu/length error in ip_forward.
	59	* Alan Cox : Avoid ip_chk_addr when possible.
	60	* Richard Underwood : IP multicasting.
	61	* Alan Cox : Cleaned up multicast handlers.
	62	* Alan Cox : RAW sockets demultiplex in the BSD style.
	63	* Gunther Mayer : Fix the SNMP reporting typo
	64	* Alan Cox : Always in group 224.0.0.1
	65	* Pauline Middelink : Fast ip_checksum update when forwarding
	66	* Masquerading support.
	67	* Alan Cox : Multicast loopback error for 224.0.0.1
	68	* Alan Cox : IP_MULTICAST_LOOP option.
	69	* Alan Cox : Use notifiers.
	70	* Bjorn Ekwall : Removed ip_csum (from slhc.c too)
	71	* Bjorn Ekwall : Moved ip_fast_csum to ip.h (inline!)
	72	* Stefan Becker : Send out ICMP HOST REDIRECT
	73	* Arnt Gulbrandsen : ip_build_xmit
	74	* Alan Cox : Per socket routing cache
	75	* Alan Cox : Fixed routing cache, added header cache.
	76	* Alan Cox : Loopback didn't work right in original ip_build_xmit - fixed it.
	77	* Alan Cox : Only send ICMP_REDIRECT if src/dest are the same net.
	78	* Alan Cox : Incoming IP option handling.
	79	* Alan Cox : Set saddr on raw output frames as per BSD.
	80	* Alan Cox : Stopped broadcast source route explosions.
81	* Alan Cox : Can disable source routing
82	* Takeshi Sone : Masquerading didn't work.
83	* Dave Bonn,Alan Cox : Faster IP forwarding whenever possible.
84	* Alan Cox : Memory leaks, tramples, misc debugging.
85	* Alan Cox : Fixed multicast (by popular demand 8))
86	* Alan Cox : Fixed forwarding (by even more popular demand 8))
87	* Alan Cox : Fixed SNMP statistics [I think]
88	* Gerhard Koerting : IP fragmentation forwarding fix
89	* Alan Cox : Device lock against page fault.
90	* Alan Cox : IP_HDRINCL facility.
91	* Werner Almesberger : Zero fragment bug
92	* Alan Cox : RAW IP frame length bug
93	* Alan Cox : Outgoing firewall on build_xmit
94	* A.N.Kuznetsov : IP_OPTIONS support throughout the kernel
95	* Alan Cox : Multicast routing hooks
96	* Jos Vos : Do accounting before call_in_firewall
97	* Willy Konynenberg : Transparent proxying support
98	*
e905a9ed	99	*
1da177e4 LT	100	*
	101	* To Fix:
	102	* IP fragmentation wants rewriting cleanly. The RFC815 algorithm is much more efficient
	103	* and could be made very efficient with the addition of some virtual memory hacks to permit
	104	* the allocation of a buffer that can then be 'grown' by twiddling page tables.
e905a9ed	105	* Output fragmentation wants updating along with the buffer management to use a single
1da177e4 LT	106	* interleaved copy algorithm so that fragmenting has a one copy overhead. Actual packet
	107	* output should probably do its own fragmentation at the UDP/RAW layer. TCP shouldn't cause
	108	* fragmentation anyway.
	109	*
	110	* This program is free software; you can redistribute it and/or
	111	* modify it under the terms of the GNU General Public License
	112	* as published by the Free Software Foundation; either version
	113	* 2 of the License, or (at your option) any later version.
	114	*/
	115
	116	#include <asm/system.h>
	117	#include <linux/module.h>
	118	#include <linux/types.h>
	119	#include <linux/kernel.h>
	120	#include <linux/string.h>
	121	#include <linux/errno.h>
5a0e3ad6	122	#include <linux/slab.h>
1da177e4 LT	123
	124	#include <linux/net.h>
	125	#include <linux/socket.h>
	126	#include <linux/sockios.h>
	127	#include <linux/in.h>
	128	#include <linux/inet.h>
14c85021	129	#include <linux/inetdevice.h>
1da177e4 LT	130	#include <linux/netdevice.h>
	131	#include <linux/etherdevice.h>
	132
	133	#include <net/snmp.h>
	134	#include <net/ip.h>
	135	#include <net/protocol.h>
	136	#include <net/route.h>
	137	#include <linux/skbuff.h>
	138	#include <net/sock.h>
	139	#include <net/arp.h>
	140	#include <net/icmp.h>
	141	#include <net/raw.h>
	142	#include <net/checksum.h>
	143	#include <linux/netfilter_ipv4.h>
	144	#include <net/xfrm.h>
	145	#include <linux/mroute.h>
	146	#include <linux/netlink.h>
	147
1da177e4	148	/*
66018506	149	* Process Router Attention IP option (RFC 2113)
e905a9ed	150	*/
1da177e4 LT	151	int ip_call_ra_chain(struct sk_buff *skb)
	152	{
	153	struct ip_ra_chain *ra;
eddc9ec5	154	u8 protocol = ip_hdr(skb)->protocol;
1da177e4	155	struct sock *last = NULL;
cb84663e	156	struct net_device *dev = skb->dev;
1da177e4	157
66018506	158	for (ra = rcu_dereference(ip_ra_chain); ra; ra = rcu_dereference(ra->next)) {
1da177e4 LT	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	*/
c720c7e8	164	if (sk && inet_sk(sk)->inet_num == protocol &&
1da177e4	165	(!sk->sk_bound_dev_if \|\|
cb84663e	166	sk->sk_bound_dev_if == dev->ifindex) &&
09ad9bc7	167	net_eq(sock_net(sk), dev_net(dev))) {
eddc9ec5	168	if (ip_hdr(skb)->frag_off & htons(IP_MF \| IP_OFFSET)) {
66018506	169	if (ip_defrag(skb, IP_DEFRAG_CALL_RA_CHAIN))
1da177e4	170	return 1;
1da177e4 LT	171	}
	172	if (last) {
	173	struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
	174	if (skb2)
	175	raw_rcv(last, skb2);
	176	}
	177	last = sk;
	178	}
	179	}
	180
	181	if (last) {
	182	raw_rcv(last, skb);
1da177e4 LT	183	return 1;
1da177e4 LT	184	}
1da177e4 LT	185	return 0;
	186	}
	187
861d0486	188	static int ip_local_deliver_finish(struct sk_buff *skb)
1da177e4	189	{
c346dca1	190	struct net *net = dev_net(skb->dev);
f145049a	191
c9bdd4b5	192	__skb_pull(skb, ip_hdrlen(skb));
1da177e4	193
e905a9ed	194	/* Point into the IP datagram, just past the header. */
badff6d0	195	skb_reset_transport_header(skb);
1da177e4 LT	196
	197	rcu_read_lock();
	198	{
eddc9ec5	199	int protocol = ip_hdr(skb)->protocol;
7bc54c90	200	int hash, raw;
32613090	201	const struct net_protocol *ipprot;
1da177e4 LT	202
1da177e4 LT	203	resubmit:
7bc54c90	204	raw = raw_local_deliver(skb, protocol);
1da177e4	205
7bc54c90	206	hash = protocol & (MAX_INET_PROTOS - 1);
f145049a	207	ipprot = rcu_dereference(inet_protos[hash]);
9c0188ac	208	if (ipprot != NULL) {
1da177e4 LT	209	int ret;
1da177e4 LT	210
9c0188ac AD	211	if (!net_eq(net, &init_net) && !ipprot->netns_ok) {
	212	if (net_ratelimit())
	213	printk("%s: proto %d isn't netns-ready\n",
	214	__func__, protocol);
	215	kfree_skb(skb);
	216	goto out;
	217	}
	218
b59c2701 PM	219	if (!ipprot->no_policy) {
	220	if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
	221	kfree_skb(skb);
	222	goto out;
	223	}
	224	nf_reset(skb);
1da177e4 LT	225	}
	226	ret = ipprot->handler(skb);
	227	if (ret < 0) {
	228	protocol = -ret;
	229	goto resubmit;
	230	}
7c73a6fa	231	IP_INC_STATS_BH(net, IPSTATS_MIB_INDELIVERS);
1da177e4	232	} else {
7bc54c90	233	if (!raw) {
1da177e4	234	if (xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
7c73a6fa	235	IP_INC_STATS_BH(net, IPSTATS_MIB_INUNKNOWNPROTOS);
1da177e4 LT	236	icmp_send(skb, ICMP_DEST_UNREACH,
	237	ICMP_PROT_UNREACH, 0);
	238	}
	239	} else
7c73a6fa	240	IP_INC_STATS_BH(net, IPSTATS_MIB_INDELIVERS);
1da177e4 LT	241	kfree_skb(skb);
	242	}
	243	}
	244	out:
	245	rcu_read_unlock();
	246
	247	return 0;
	248	}
	249
	250	/*
	251	* Deliver IP Packets to the higher protocol layers.
e905a9ed	252	*/
1da177e4 LT	253	int ip_local_deliver(struct sk_buff *skb)
	254	{
	255	/*
	256	* Reassemble IP fragments.
	257	*/
	258
eddc9ec5	259	if (ip_hdr(skb)->frag_off & htons(IP_MF \| IP_OFFSET)) {
776c729e	260	if (ip_defrag(skb, IP_DEFRAG_LOCAL_DELIVER))
1da177e4 LT	261	return 0;
	262	}
	263
9bbc768a	264	return NF_HOOK(NFPROTO_IPV4, NF_INET_LOCAL_IN, skb, skb->dev, NULL,
1da177e4 LT	265	ip_local_deliver_finish);
	266	}
	267
d245407e TG	268	static inline int ip_rcv_options(struct sk_buff *skb)
	269	{
	270	struct ip_options *opt;
	271	struct iphdr *iph;
	272	struct net_device *dev = skb->dev;
	273
	274	/* It looks as overkill, because not all
	275	IP options require packet mangling.
	276	But it is the easiest for now, especially taking
	277	into account that combination of IP options
	278	and running sniffer is extremely rare condition.
	279	--ANK (980813)
	280	*/
	281	if (skb_cow(skb, skb_headroom(skb))) {
7c73a6fa	282	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
d245407e TG	283	goto drop;
	284	}
	285
eddc9ec5	286	iph = ip_hdr(skb);
22aba383 DL	287	opt = &(IPCB(skb)->opt);
22aba383 DL	288	opt->optlen = iph->ihl*4 - sizeof(struct iphdr);
d245407e	289
c346dca1	290	if (ip_options_compile(dev_net(dev), opt, skb)) {
7c73a6fa	291	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INHDRERRORS);
d245407e TG	292	goto drop;
	293	}
	294
d245407e	295	if (unlikely(opt->srr)) {
6e8b11b4 ED	296	struct in_device *in_dev = __in_dev_get_rcu(dev);
6e8b11b4 ED	297
d245407e TG	298	if (in_dev) {
	299	if (!IN_DEV_SOURCE_ROUTE(in_dev)) {
	300	if (IN_DEV_LOG_MARTIANS(in_dev) &&
	301	net_ratelimit())
673d57e7 HH	302	printk(KERN_INFO "source route option %pI4 -> %pI4\n",
673d57e7 HH	303	&iph->saddr, &iph->daddr);
d245407e TG	304	goto drop;
d245407e TG	305	}
d245407e TG	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	*/
adf30907	326	if (skb_dst(skb) == NULL) {
4a94445c ED	327	int err = ip_route_input_noref(skb, iph->daddr, iph->saddr,
4a94445c ED	328	iph->tos, skb->dev);
3e192bea	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);
b5f7e755 ED	336	else if (err == -EXDEV)
	337	NET_INC_STATS_BH(dev_net(skb->dev),
	338	LINUX_MIB_IPRPFILTER);
e905a9ed	339	goto drop;
2c2910a4	340	}
1da177e4 LT	341	}
	342
	343	#ifdef CONFIG_NET_CLS_ROUTE
adf30907	344	if (unlikely(skb_dst(skb)->tclassid)) {
7a9b2d59	345	struct ip_rt_acct *st = this_cpu_ptr(ip_rt_acct);
adf30907	346	u32 idx = skb_dst(skb)->tclassid;
1da177e4	347	st[idx&0xFF].o_packets++;
fd3f8c4c	348	st[idx&0xFF].o_bytes += skb->len;
1da177e4	349	st[(idx>>16)&0xFF].i_packets++;
fd3f8c4c	350	st[(idx>>16)&0xFF].i_bytes += skb->len;
1da177e4 LT	351	}
	352	#endif
	353
d245407e TG	354	if (iph->ihl > 5 && ip_rcv_options(skb))
d245407e TG	355	goto drop;
1da177e4	356
511c3f92	357	rt = skb_rtable(skb);
edf391ff	358	if (rt->rt_type == RTN_MULTICAST) {
d8d1f30b	359	IP_UPD_PO_STATS_BH(dev_net(rt->dst.dev), IPSTATS_MIB_INMCAST,
edf391ff NH	360	skb->len);
edf391ff NH	361	} else if (rt->rt_type == RTN_BROADCAST)
d8d1f30b	362	IP_UPD_PO_STATS_BH(dev_net(rt->dst.dev), IPSTATS_MIB_INBCAST,
edf391ff	363	skb->len);
5506b54b	364
1da177e4 LT	365	return dst_input(skb);
1da177e4 LT	366
1da177e4	367	drop:
e905a9ed YH	368	kfree_skb(skb);
e905a9ed YH	369	return NET_RX_DROP;
1da177e4 LT	370	}
	371
	372	/*
	373	* Main IP Receive routine.
e905a9ed	374	*/
f2ccd8fa	375	int ip_rcv(struct sk_buff skb, struct net_device dev, struct packet_type pt, struct net_device orig_dev)
1da177e4 LT	376	{
1da177e4 LT	377	struct iphdr *iph;
58615242	378	u32 len;
1da177e4 LT	379
	380	/* When the interface is in promisc. mode, drop all the crap
	381	* that it receives, do not try to analyse it.
	382	*/
	383	if (skb->pkt_type == PACKET_OTHERHOST)
	384	goto drop;
	385
edf391ff NH	386
edf391ff NH	387	IP_UPD_PO_STATS_BH(dev_net(dev), IPSTATS_MIB_IN, skb->len);
1da177e4 LT	388
1da177e4 LT	389	if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL) {
7c73a6fa	390	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
1da177e4 LT	391	goto out;
	392	}
	393
	394	if (!pskb_may_pull(skb, sizeof(struct iphdr)))
	395	goto inhdr_error;
	396
eddc9ec5	397	iph = ip_hdr(skb);
1da177e4 LT	398
1da177e4 LT	399	/*
c67fa027	400	* RFC1122: 3.2.1.2 MUST silently discard any IP frame that fails the checksum.
1da177e4 LT	401	*
	402	* Is the datagram acceptable?
	403	*
	404	* 1. Length at least the size of an ip header
	405	* 2. Version of 4
	406	* 3. Checksums correctly. [Speed optimisation for later, skip loopback checksums]
	407	* 4. Doesn't have a bogus length
	408	*/
	409
	410	if (iph->ihl < 5 \|\| iph->version != 4)
58615242	411	goto inhdr_error;
1da177e4 LT	412
	413	if (!pskb_may_pull(skb, iph->ihl*4))
	414	goto inhdr_error;
	415
eddc9ec5	416	iph = ip_hdr(skb);
1da177e4	417
e9c60422	418	if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
58615242	419	goto inhdr_error;
1da177e4	420
58615242	421	len = ntohs(iph->tot_len);
704aed53	422	if (skb->len < len) {
7c73a6fa	423	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INTRUNCATEDPKTS);
704aed53 MC	424	goto drop;
704aed53 MC	425	} else if (len < (iph->ihl*4))
58615242	426	goto inhdr_error;
1da177e4	427
58615242 TG	428	/* Our transport medium may have padded the buffer out. Now we know it
	429	* is IP we can trim to the true length of the frame.
	430	* Note this now means skb->len holds ntohs(iph->tot_len).
	431	*/
	432	if (pskb_trim_rcsum(skb, len)) {
7c73a6fa	433	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
58615242	434	goto drop;
1da177e4 LT	435	}
1da177e4 LT	436
53602f92	437	/* Remove any debris in the socket control block */
d569f1d7	438	memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
53602f92	439
71f9dacd HX	440	/* Must drop socket now because of tproxy. */
	441	skb_orphan(skb);
	442
9bbc768a	443	return NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, skb, dev, NULL,
1da177e4 LT	444	ip_rcv_finish);
	445
	446	inhdr_error:
7c73a6fa	447	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INHDRERRORS);
1da177e4	448	drop:
e905a9ed	449	kfree_skb(skb);
1da177e4	450	out:
e905a9ed	451	return NET_RX_DROP;
1da177e4	452	}