[GitHub/mt8127/android_kernel_alcatel_ttab.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.
 */

#define pr_fmt(fmt) "IPv4: " fmt

#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)
 */
bool 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_is_fragment(ip_hdr(skb))) {
				if (ip_defrag(skb, IP_DEFRAG_CALL_RA_CHAIN))
					return true;
			}
			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 true;
	}
	return false;
}

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;
		const struct net_protocol *ipprot;
		int raw;

	resubmit:
		raw = raw_local_deliver(skb, protocol);

		ipprot = rcu_dereference(inet_protos[protocol]);
		if (ipprot != 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(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);
				}
				kfree_skb(skb);
			} else {
				IP_INC_STATS_BH(net, IPSTATS_MIB_INDELIVERS);
				consume_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_is_fragment(ip_hdr(skb))) {
		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 bool ip_rcv_options(struct sk_buff *skb)
{
	struct ip_options *opt;
	const 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_info_ratelimited("source route option %pI4 -> %pI4\n",
							     &iph->saddr,
							     &iph->daddr);
				goto drop;
			}
		}

		if (ip_options_rcv_srr(skb))
			goto drop;
	}

	return false;
drop:
	return true;
}

int sysctl_ip_early_demux __read_mostly = 1;
EXPORT_SYMBOL(sysctl_ip_early_demux);

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

	if (sysctl_ip_early_demux && !skb_dst(skb)) {
		const struct net_protocol *ipprot;
		int protocol = iph->protocol;

		ipprot = rcu_dereference(inet_protos[protocol]);
		if (ipprot && ipprot->early_demux) {
			ipprot->early_demux(skb);
			/* must reload iph, skb->head might have changed */
			iph = ip_hdr(skb);
		}
	}

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

#ifdef CONFIG_IP_ROUTE_CLASSID
	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)
{
	const 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 csum_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);

csum_error:
	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_CSUMERRORS);
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
afd46503 JP	116	#define pr_fmt(fmt) "IPv4: " fmt
afd46503 JP	117
1da177e4 LT	118	#include <linux/module.h>
	119	#include <linux/types.h>
	120	#include <linux/kernel.h>
	121	#include <linux/string.h>
	122	#include <linux/errno.h>
5a0e3ad6	123	#include <linux/slab.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
1da177e4	149	/*
66018506	150	* Process Router Attention IP option (RFC 2113)
e905a9ed	151	*/
ba57b4db	152	bool ip_call_ra_chain(struct sk_buff *skb)
1da177e4 LT	153	{
1da177e4 LT	154	struct ip_ra_chain *ra;
eddc9ec5	155	u8 protocol = ip_hdr(skb)->protocol;
1da177e4	156	struct sock *last = NULL;
cb84663e	157	struct net_device *dev = skb->dev;
1da177e4	158
66018506	159	for (ra = rcu_dereference(ip_ra_chain); ra; ra = rcu_dereference(ra->next)) {
1da177e4 LT	160	struct sock *sk = ra->sk;
	161
	162	/* If socket is bound to an interface, only report
	163	* the packet if it came from that interface.
	164	*/
c720c7e8	165	if (sk && inet_sk(sk)->inet_num == protocol &&
1da177e4	166	(!sk->sk_bound_dev_if \|\|
cb84663e	167	sk->sk_bound_dev_if == dev->ifindex) &&
09ad9bc7	168	net_eq(sock_net(sk), dev_net(dev))) {
56f8a75c	169	if (ip_is_fragment(ip_hdr(skb))) {
66018506	170	if (ip_defrag(skb, IP_DEFRAG_CALL_RA_CHAIN))
ba57b4db	171	return true;
1da177e4 LT	172	}
	173	if (last) {
	174	struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
	175	if (skb2)
	176	raw_rcv(last, skb2);
	177	}
	178	last = sk;
	179	}
	180	}
	181
	182	if (last) {
	183	raw_rcv(last, skb);
ba57b4db	184	return true;
1da177e4	185	}
ba57b4db	186	return false;
1da177e4 LT	187	}
1da177e4 LT	188
861d0486	189	static int ip_local_deliver_finish(struct sk_buff *skb)
1da177e4	190	{
c346dca1	191	struct net *net = dev_net(skb->dev);
f145049a	192
c9bdd4b5	193	__skb_pull(skb, ip_hdrlen(skb));
1da177e4	194
e905a9ed	195	/* Point into the IP datagram, just past the header. */
badff6d0	196	skb_reset_transport_header(skb);
1da177e4 LT	197
	198	rcu_read_lock();
	199	{
eddc9ec5	200	int protocol = ip_hdr(skb)->protocol;
32613090	201	const struct net_protocol *ipprot;
f9242b6b	202	int raw;
1da177e4 LT	203
1da177e4 LT	204	resubmit:
7bc54c90	205	raw = raw_local_deliver(skb, protocol);
1da177e4	206
f9242b6b	207	ipprot = rcu_dereference(inet_protos[protocol]);
9c0188ac	208	if (ipprot != NULL) {
1da177e4 LT	209	int ret;
1da177e4 LT	210
b59c2701 PM	211	if (!ipprot->no_policy) {
	212	if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
	213	kfree_skb(skb);
	214	goto out;
	215	}
	216	nf_reset(skb);
1da177e4 LT	217	}
	218	ret = ipprot->handler(skb);
	219	if (ret < 0) {
	220	protocol = -ret;
	221	goto resubmit;
	222	}
7c73a6fa	223	IP_INC_STATS_BH(net, IPSTATS_MIB_INDELIVERS);
1da177e4	224	} else {
7bc54c90	225	if (!raw) {
1da177e4	226	if (xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
7c73a6fa	227	IP_INC_STATS_BH(net, IPSTATS_MIB_INUNKNOWNPROTOS);
1da177e4 LT	228	icmp_send(skb, ICMP_DEST_UNREACH,
	229	ICMP_PROT_UNREACH, 0);
	230	}
d8c6f4b9 NH	231	kfree_skb(skb);
d8c6f4b9 NH	232	} else {
7c73a6fa	233	IP_INC_STATS_BH(net, IPSTATS_MIB_INDELIVERS);
d8c6f4b9 NH	234	consume_skb(skb);
d8c6f4b9 NH	235	}
1da177e4 LT	236	}
	237	}
	238	out:
	239	rcu_read_unlock();
	240
	241	return 0;
	242	}
	243
	244	/*
	245	* Deliver IP Packets to the higher protocol layers.
e905a9ed	246	*/
1da177e4 LT	247	int ip_local_deliver(struct sk_buff *skb)
	248	{
	249	/*
	250	* Reassemble IP fragments.
	251	*/
	252
56f8a75c	253	if (ip_is_fragment(ip_hdr(skb))) {
776c729e	254	if (ip_defrag(skb, IP_DEFRAG_LOCAL_DELIVER))
1da177e4 LT	255	return 0;
	256	}
	257
9bbc768a	258	return NF_HOOK(NFPROTO_IPV4, NF_INET_LOCAL_IN, skb, skb->dev, NULL,
1da177e4 LT	259	ip_local_deliver_finish);
	260	}
	261
6a91395f	262	static inline bool ip_rcv_options(struct sk_buff *skb)
d245407e TG	263	{
d245407e TG	264	struct ip_options *opt;
b71d1d42	265	const struct iphdr *iph;
d245407e TG	266	struct net_device *dev = skb->dev;
	267
	268	/* It looks as overkill, because not all
	269	IP options require packet mangling.
	270	But it is the easiest for now, especially taking
	271	into account that combination of IP options
	272	and running sniffer is extremely rare condition.
	273	--ANK (980813)
	274	*/
	275	if (skb_cow(skb, skb_headroom(skb))) {
7c73a6fa	276	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
d245407e TG	277	goto drop;
	278	}
	279
eddc9ec5	280	iph = ip_hdr(skb);
22aba383 DL	281	opt = &(IPCB(skb)->opt);
22aba383 DL	282	opt->optlen = iph->ihl*4 - sizeof(struct iphdr);
d245407e	283
c346dca1	284	if (ip_options_compile(dev_net(dev), opt, skb)) {
7c73a6fa	285	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INHDRERRORS);
d245407e TG	286	goto drop;
	287	}
	288
d245407e	289	if (unlikely(opt->srr)) {
6e8b11b4 ED	290	struct in_device *in_dev = __in_dev_get_rcu(dev);
6e8b11b4 ED	291
d245407e TG	292	if (in_dev) {
d245407e TG	293	if (!IN_DEV_SOURCE_ROUTE(in_dev)) {
e87cc472 JP	294	if (IN_DEV_LOG_MARTIANS(in_dev))
	295	net_info_ratelimited("source route option %pI4 -> %pI4\n",
	296	&iph->saddr,
	297	&iph->daddr);
d245407e TG	298	goto drop;
d245407e TG	299	}
d245407e TG	300	}
	301
	302	if (ip_options_rcv_srr(skb))
	303	goto drop;
	304	}
	305
6a91395f	306	return false;
d245407e	307	drop:
6a91395f	308	return true;
d245407e TG	309	}
d245407e TG	310
6648bd7e	311	int sysctl_ip_early_demux __read_mostly = 1;
c7109986	312	EXPORT_SYMBOL(sysctl_ip_early_demux);
6648bd7e	313
861d0486	314	static int ip_rcv_finish(struct sk_buff *skb)
1da177e4	315	{
eddc9ec5	316	const struct iphdr *iph = ip_hdr(skb);
5506b54b	317	struct rtable *rt;
1da177e4	318
160eb5a6 DM	319	if (sysctl_ip_early_demux && !skb_dst(skb)) {
	320	const struct net_protocol *ipprot;
	321	int protocol = iph->protocol;
	322
160eb5a6	323	ipprot = rcu_dereference(inet_protos[protocol]);
9cb429d6	324	if (ipprot && ipprot->early_demux) {
160eb5a6	325	ipprot->early_demux(skb);
9cb429d6 ED	326	/* must reload iph, skb->head might have changed */
	327	iph = ip_hdr(skb);
	328	}
160eb5a6 DM	329	}
160eb5a6 DM	330
1da177e4 LT	331	/*
	332	* Initialise the virtual path cache for the packet. It describes
	333	* how the packet travels inside Linux networking.
e905a9ed	334	*/
160eb5a6	335	if (!skb_dst(skb)) {
c6cffba4 DM	336	int err = ip_route_input_noref(skb, iph->daddr, iph->saddr,
c6cffba4 DM	337	iph->tos, skb->dev);
160eb5a6 DM	338	if (unlikely(err)) {
	339	if (err == -EXDEV)
	340	NET_INC_STATS_BH(dev_net(skb->dev),
	341	LINUX_MIB_IPRPFILTER);
	342	goto drop;
2c2910a4	343	}
1da177e4 LT	344	}
1da177e4 LT	345
c7066f70	346	#ifdef CONFIG_IP_ROUTE_CLASSID
adf30907	347	if (unlikely(skb_dst(skb)->tclassid)) {
7a9b2d59	348	struct ip_rt_acct *st = this_cpu_ptr(ip_rt_acct);
adf30907	349	u32 idx = skb_dst(skb)->tclassid;
1da177e4	350	st[idx&0xFF].o_packets++;
fd3f8c4c	351	st[idx&0xFF].o_bytes += skb->len;
1da177e4	352	st[(idx>>16)&0xFF].i_packets++;
fd3f8c4c	353	st[(idx>>16)&0xFF].i_bytes += skb->len;
1da177e4 LT	354	}
	355	#endif
	356
d245407e TG	357	if (iph->ihl > 5 && ip_rcv_options(skb))
d245407e TG	358	goto drop;
1da177e4	359
511c3f92	360	rt = skb_rtable(skb);
edf391ff	361	if (rt->rt_type == RTN_MULTICAST) {
d8d1f30b	362	IP_UPD_PO_STATS_BH(dev_net(rt->dst.dev), IPSTATS_MIB_INMCAST,
edf391ff NH	363	skb->len);
edf391ff NH	364	} else if (rt->rt_type == RTN_BROADCAST)
d8d1f30b	365	IP_UPD_PO_STATS_BH(dev_net(rt->dst.dev), IPSTATS_MIB_INBCAST,
edf391ff	366	skb->len);
5506b54b	367
1da177e4 LT	368	return dst_input(skb);
1da177e4 LT	369
1da177e4	370	drop:
e905a9ed YH	371	kfree_skb(skb);
e905a9ed YH	372	return NET_RX_DROP;
1da177e4 LT	373	}
	374
	375	/*
	376	* Main IP Receive routine.
e905a9ed	377	*/
f2ccd8fa	378	int ip_rcv(struct sk_buff skb, struct net_device dev, struct packet_type pt, struct net_device orig_dev)
1da177e4	379	{
b71d1d42	380	const struct iphdr *iph;
58615242	381	u32 len;
1da177e4 LT	382
	383	/* When the interface is in promisc. mode, drop all the crap
	384	* that it receives, do not try to analyse it.
	385	*/
	386	if (skb->pkt_type == PACKET_OTHERHOST)
	387	goto drop;
	388
edf391ff NH	389
edf391ff NH	390	IP_UPD_PO_STATS_BH(dev_net(dev), IPSTATS_MIB_IN, skb->len);
1da177e4 LT	391
1da177e4 LT	392	if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL) {
7c73a6fa	393	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
1da177e4 LT	394	goto out;
	395	}
	396
	397	if (!pskb_may_pull(skb, sizeof(struct iphdr)))
	398	goto inhdr_error;
	399
eddc9ec5	400	iph = ip_hdr(skb);
1da177e4 LT	401
1da177e4 LT	402	/*
c67fa027	403	* RFC1122: 3.2.1.2 MUST silently discard any IP frame that fails the checksum.
1da177e4 LT	404	*
	405	* Is the datagram acceptable?
	406	*
	407	* 1. Length at least the size of an ip header
	408	* 2. Version of 4
	409	* 3. Checksums correctly. [Speed optimisation for later, skip loopback checksums]
	410	* 4. Doesn't have a bogus length
	411	*/
	412
	413	if (iph->ihl < 5 \|\| iph->version != 4)
58615242	414	goto inhdr_error;
1da177e4 LT	415
	416	if (!pskb_may_pull(skb, iph->ihl*4))
	417	goto inhdr_error;
	418
eddc9ec5	419	iph = ip_hdr(skb);
1da177e4	420
e9c60422	421	if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
6a5dc9e5	422	goto csum_error;
1da177e4	423
58615242	424	len = ntohs(iph->tot_len);
704aed53	425	if (skb->len < len) {
7c73a6fa	426	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INTRUNCATEDPKTS);
704aed53 MC	427	goto drop;
704aed53 MC	428	} else if (len < (iph->ihl*4))
58615242	429	goto inhdr_error;
1da177e4	430
58615242 TG	431	/* Our transport medium may have padded the buffer out. Now we know it
	432	* is IP we can trim to the true length of the frame.
	433	* Note this now means skb->len holds ntohs(iph->tot_len).
	434	*/
	435	if (pskb_trim_rcsum(skb, len)) {
7c73a6fa	436	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
58615242	437	goto drop;
1da177e4 LT	438	}
1da177e4 LT	439
53602f92	440	/* Remove any debris in the socket control block */
d569f1d7	441	memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
53602f92	442
71f9dacd HX	443	/* Must drop socket now because of tproxy. */
	444	skb_orphan(skb);
	445
9bbc768a	446	return NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, skb, dev, NULL,
1da177e4 LT	447	ip_rcv_finish);
1da177e4 LT	448
6a5dc9e5 ED	449	csum_error:
6a5dc9e5 ED	450	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_CSUMERRORS);
1da177e4	451	inhdr_error:
7c73a6fa	452	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INHDRERRORS);
1da177e4	453	drop:
e905a9ed	454	kfree_skb(skb);
1da177e4	455	out:
e905a9ed	456	return NET_RX_DROP;
1da177e4	457	}