[mirror_ubuntu-jammy-kernel.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, skb_network_header_len(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;
	}

	skb->transport_header = skb->network_header + iph->ihl*4;

	/* 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
21d1196a	193	__skb_pull(skb, skb_network_header_len(skb));
1da177e4 LT	194
	195	rcu_read_lock();
	196	{
eddc9ec5	197	int protocol = ip_hdr(skb)->protocol;
32613090	198	const struct net_protocol *ipprot;
f9242b6b	199	int raw;
1da177e4 LT	200
1da177e4 LT	201	resubmit:
7bc54c90	202	raw = raw_local_deliver(skb, protocol);
1da177e4	203
f9242b6b	204	ipprot = rcu_dereference(inet_protos[protocol]);
9c0188ac	205	if (ipprot != NULL) {
1da177e4 LT	206	int ret;
1da177e4 LT	207
b59c2701 PM	208	if (!ipprot->no_policy) {
	209	if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
	210	kfree_skb(skb);
	211	goto out;
	212	}
	213	nf_reset(skb);
1da177e4 LT	214	}
	215	ret = ipprot->handler(skb);
	216	if (ret < 0) {
	217	protocol = -ret;
	218	goto resubmit;
	219	}
7c73a6fa	220	IP_INC_STATS_BH(net, IPSTATS_MIB_INDELIVERS);
1da177e4	221	} else {
7bc54c90	222	if (!raw) {
1da177e4	223	if (xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
7c73a6fa	224	IP_INC_STATS_BH(net, IPSTATS_MIB_INUNKNOWNPROTOS);
1da177e4 LT	225	icmp_send(skb, ICMP_DEST_UNREACH,
	226	ICMP_PROT_UNREACH, 0);
	227	}
d8c6f4b9 NH	228	kfree_skb(skb);
d8c6f4b9 NH	229	} else {
7c73a6fa	230	IP_INC_STATS_BH(net, IPSTATS_MIB_INDELIVERS);
d8c6f4b9 NH	231	consume_skb(skb);
d8c6f4b9 NH	232	}
1da177e4 LT	233	}
	234	}
	235	out:
	236	rcu_read_unlock();
	237
	238	return 0;
	239	}
	240
	241	/*
	242	* Deliver IP Packets to the higher protocol layers.
e905a9ed	243	*/
1da177e4 LT	244	int ip_local_deliver(struct sk_buff *skb)
	245	{
	246	/*
	247	* Reassemble IP fragments.
	248	*/
	249
56f8a75c	250	if (ip_is_fragment(ip_hdr(skb))) {
776c729e	251	if (ip_defrag(skb, IP_DEFRAG_LOCAL_DELIVER))
1da177e4 LT	252	return 0;
	253	}
	254
9bbc768a	255	return NF_HOOK(NFPROTO_IPV4, NF_INET_LOCAL_IN, skb, skb->dev, NULL,
1da177e4 LT	256	ip_local_deliver_finish);
	257	}
	258
6a91395f	259	static inline bool ip_rcv_options(struct sk_buff *skb)
d245407e TG	260	{
d245407e TG	261	struct ip_options *opt;
b71d1d42	262	const struct iphdr *iph;
d245407e TG	263	struct net_device *dev = skb->dev;
	264
	265	/* It looks as overkill, because not all
	266	IP options require packet mangling.
	267	But it is the easiest for now, especially taking
	268	into account that combination of IP options
	269	and running sniffer is extremely rare condition.
	270	--ANK (980813)
	271	*/
	272	if (skb_cow(skb, skb_headroom(skb))) {
7c73a6fa	273	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
d245407e TG	274	goto drop;
	275	}
	276
eddc9ec5	277	iph = ip_hdr(skb);
22aba383 DL	278	opt = &(IPCB(skb)->opt);
22aba383 DL	279	opt->optlen = iph->ihl*4 - sizeof(struct iphdr);
d245407e	280
c346dca1	281	if (ip_options_compile(dev_net(dev), opt, skb)) {
7c73a6fa	282	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INHDRERRORS);
d245407e TG	283	goto drop;
	284	}
	285
d245407e	286	if (unlikely(opt->srr)) {
6e8b11b4 ED	287	struct in_device *in_dev = __in_dev_get_rcu(dev);
6e8b11b4 ED	288
d245407e TG	289	if (in_dev) {
d245407e TG	290	if (!IN_DEV_SOURCE_ROUTE(in_dev)) {
e87cc472 JP	291	if (IN_DEV_LOG_MARTIANS(in_dev))
	292	net_info_ratelimited("source route option %pI4 -> %pI4\n",
	293	&iph->saddr,
	294	&iph->daddr);
d245407e TG	295	goto drop;
d245407e TG	296	}
d245407e TG	297	}
	298
	299	if (ip_options_rcv_srr(skb))
	300	goto drop;
	301	}
	302
6a91395f	303	return false;
d245407e	304	drop:
6a91395f	305	return true;
d245407e TG	306	}
d245407e TG	307
6648bd7e	308	int sysctl_ip_early_demux __read_mostly = 1;
c7109986	309	EXPORT_SYMBOL(sysctl_ip_early_demux);
6648bd7e	310
861d0486	311	static int ip_rcv_finish(struct sk_buff *skb)
1da177e4	312	{
eddc9ec5	313	const struct iphdr *iph = ip_hdr(skb);
5506b54b	314	struct rtable *rt;
1da177e4	315
160eb5a6 DM	316	if (sysctl_ip_early_demux && !skb_dst(skb)) {
	317	const struct net_protocol *ipprot;
	318	int protocol = iph->protocol;
	319
160eb5a6	320	ipprot = rcu_dereference(inet_protos[protocol]);
9cb429d6	321	if (ipprot && ipprot->early_demux) {
160eb5a6	322	ipprot->early_demux(skb);
9cb429d6 ED	323	/* must reload iph, skb->head might have changed */
	324	iph = ip_hdr(skb);
	325	}
160eb5a6 DM	326	}
160eb5a6 DM	327
1da177e4 LT	328	/*
	329	* Initialise the virtual path cache for the packet. It describes
	330	* how the packet travels inside Linux networking.
e905a9ed	331	*/
160eb5a6	332	if (!skb_dst(skb)) {
c6cffba4 DM	333	int err = ip_route_input_noref(skb, iph->daddr, iph->saddr,
c6cffba4 DM	334	iph->tos, skb->dev);
160eb5a6 DM	335	if (unlikely(err)) {
	336	if (err == -EXDEV)
	337	NET_INC_STATS_BH(dev_net(skb->dev),
	338	LINUX_MIB_IPRPFILTER);
	339	goto drop;
2c2910a4	340	}
1da177e4 LT	341	}
1da177e4 LT	342
c7066f70	343	#ifdef CONFIG_IP_ROUTE_CLASSID
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	376	{
b71d1d42	377	const 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)))
6a5dc9e5	419	goto csum_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
21d1196a ED	437	skb->transport_header = skb->network_header + iph->ihl*4;
21d1196a ED	438
53602f92	439	/* Remove any debris in the socket control block */
d569f1d7	440	memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
53602f92	441
71f9dacd HX	442	/* Must drop socket now because of tproxy. */
	443	skb_orphan(skb);
	444
9bbc768a	445	return NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, skb, dev, NULL,
1da177e4 LT	446	ip_rcv_finish);
1da177e4 LT	447
6a5dc9e5 ED	448	csum_error:
6a5dc9e5 ED	449	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_CSUMERRORS);
1da177e4	450	inhdr_error:
7c73a6fa	451	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INHDRERRORS);
1da177e4	452	drop:
e905a9ed	453	kfree_skb(skb);
1da177e4	454	out:
e905a9ed	455	return NET_RX_DROP;
1da177e4	456	}