[mirror_ubuntu-artful-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 <net/inet_ecn.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 sock *sk, 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) {
			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, NULL, 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 sock *sk, struct sk_buff *skb)
{
	const struct iphdr *iph = ip_hdr(skb);
	struct rtable *rt;

	if (sysctl_ip_early_demux && !skb_dst(skb) && !skb->sk) {
		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);

	skb = skb_share_check(skb, GFP_ATOMIC);
	if (!skb) {
		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;

	BUILD_BUG_ON(IPSTATS_MIB_ECT1PKTS != IPSTATS_MIB_NOECTPKTS + INET_ECN_ECT_1);
	BUILD_BUG_ON(IPSTATS_MIB_ECT0PKTS != IPSTATS_MIB_NOECTPKTS + INET_ECN_ECT_0);
	BUILD_BUG_ON(IPSTATS_MIB_CEPKTS != IPSTATS_MIB_NOECTPKTS + INET_ECN_CE);
	IP_ADD_STATS_BH(dev_net(dev),
			IPSTATS_MIB_NOECTPKTS + (iph->tos & INET_ECN_MASK),
			max_t(unsigned short, 1, skb_shinfo(skb)->gso_segs));

	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, NULL, 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>
1f07d03e	144	#include <net/inet_ecn.h>
1da177e4 LT	145	#include <linux/netfilter_ipv4.h>
	146	#include <net/xfrm.h>
	147	#include <linux/mroute.h>
	148	#include <linux/netlink.h>
	149
1da177e4	150	/*
66018506	151	* Process Router Attention IP option (RFC 2113)
e905a9ed	152	*/
ba57b4db	153	bool ip_call_ra_chain(struct sk_buff *skb)
1da177e4 LT	154	{
1da177e4 LT	155	struct ip_ra_chain *ra;
eddc9ec5	156	u8 protocol = ip_hdr(skb)->protocol;
1da177e4	157	struct sock *last = NULL;
cb84663e	158	struct net_device *dev = skb->dev;
1da177e4	159
66018506	160	for (ra = rcu_dereference(ip_ra_chain); ra; ra = rcu_dereference(ra->next)) {
1da177e4 LT	161	struct sock *sk = ra->sk;
	162
	163	/* If socket is bound to an interface, only report
	164	* the packet if it came from that interface.
	165	*/
c720c7e8	166	if (sk && inet_sk(sk)->inet_num == protocol &&
1da177e4	167	(!sk->sk_bound_dev_if \|\|
cb84663e	168	sk->sk_bound_dev_if == dev->ifindex) &&
09ad9bc7	169	net_eq(sock_net(sk), dev_net(dev))) {
56f8a75c	170	if (ip_is_fragment(ip_hdr(skb))) {
66018506	171	if (ip_defrag(skb, IP_DEFRAG_CALL_RA_CHAIN))
ba57b4db	172	return true;
1da177e4 LT	173	}
	174	if (last) {
	175	struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
	176	if (skb2)
	177	raw_rcv(last, skb2);
	178	}
	179	last = sk;
	180	}
	181	}
	182
	183	if (last) {
	184	raw_rcv(last, skb);
ba57b4db	185	return true;
1da177e4	186	}
ba57b4db	187	return false;
1da177e4 LT	188	}
1da177e4 LT	189
7026b1dd	190	static int ip_local_deliver_finish(struct sock sk, struct sk_buff skb)
1da177e4	191	{
c346dca1	192	struct net *net = dev_net(skb->dev);
f145049a	193
21d1196a	194	__skb_pull(skb, skb_network_header_len(skb));
1da177e4 LT	195
	196	rcu_read_lock();
	197	{
eddc9ec5	198	int protocol = ip_hdr(skb)->protocol;
32613090	199	const struct net_protocol *ipprot;
f9242b6b	200	int raw;
1da177e4 LT	201
1da177e4 LT	202	resubmit:
7bc54c90	203	raw = raw_local_deliver(skb, protocol);
1da177e4	204
f9242b6b	205	ipprot = rcu_dereference(inet_protos[protocol]);
00db4124	206	if (ipprot) {
1da177e4 LT	207	int ret;
1da177e4 LT	208
b59c2701 PM	209	if (!ipprot->no_policy) {
	210	if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
	211	kfree_skb(skb);
	212	goto out;
	213	}
	214	nf_reset(skb);
1da177e4 LT	215	}
	216	ret = ipprot->handler(skb);
	217	if (ret < 0) {
	218	protocol = -ret;
	219	goto resubmit;
	220	}
7c73a6fa	221	IP_INC_STATS_BH(net, IPSTATS_MIB_INDELIVERS);
1da177e4	222	} else {
7bc54c90	223	if (!raw) {
1da177e4	224	if (xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
7c73a6fa	225	IP_INC_STATS_BH(net, IPSTATS_MIB_INUNKNOWNPROTOS);
1da177e4 LT	226	icmp_send(skb, ICMP_DEST_UNREACH,
	227	ICMP_PROT_UNREACH, 0);
	228	}
d8c6f4b9 NH	229	kfree_skb(skb);
d8c6f4b9 NH	230	} else {
7c73a6fa	231	IP_INC_STATS_BH(net, IPSTATS_MIB_INDELIVERS);
d8c6f4b9 NH	232	consume_skb(skb);
d8c6f4b9 NH	233	}
1da177e4 LT	234	}
	235	}
	236	out:
	237	rcu_read_unlock();
	238
	239	return 0;
	240	}
	241
	242	/*
	243	* Deliver IP Packets to the higher protocol layers.
e905a9ed	244	*/
1da177e4 LT	245	int ip_local_deliver(struct sk_buff *skb)
	246	{
	247	/*
	248	* Reassemble IP fragments.
	249	*/
	250
56f8a75c	251	if (ip_is_fragment(ip_hdr(skb))) {
776c729e	252	if (ip_defrag(skb, IP_DEFRAG_LOCAL_DELIVER))
1da177e4 LT	253	return 0;
	254	}
	255
7026b1dd DM	256	return NF_HOOK(NFPROTO_IPV4, NF_INET_LOCAL_IN, NULL, skb,
7026b1dd DM	257	skb->dev, NULL,
1da177e4 LT	258	ip_local_deliver_finish);
	259	}
	260
6a91395f	261	static inline bool ip_rcv_options(struct sk_buff *skb)
d245407e TG	262	{
d245407e TG	263	struct ip_options *opt;
b71d1d42	264	const struct iphdr *iph;
d245407e TG	265	struct net_device *dev = skb->dev;
	266
	267	/* It looks as overkill, because not all
	268	IP options require packet mangling.
	269	But it is the easiest for now, especially taking
	270	into account that combination of IP options
	271	and running sniffer is extremely rare condition.
	272	--ANK (980813)
	273	*/
	274	if (skb_cow(skb, skb_headroom(skb))) {
7c73a6fa	275	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
d245407e TG	276	goto drop;
	277	}
	278
eddc9ec5	279	iph = ip_hdr(skb);
22aba383 DL	280	opt = &(IPCB(skb)->opt);
22aba383 DL	281	opt->optlen = iph->ihl*4 - sizeof(struct iphdr);
d245407e	282
c346dca1	283	if (ip_options_compile(dev_net(dev), opt, skb)) {
7c73a6fa	284	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INHDRERRORS);
d245407e TG	285	goto drop;
	286	}
	287
d245407e	288	if (unlikely(opt->srr)) {
6e8b11b4 ED	289	struct in_device *in_dev = __in_dev_get_rcu(dev);
6e8b11b4 ED	290
d245407e TG	291	if (in_dev) {
d245407e TG	292	if (!IN_DEV_SOURCE_ROUTE(in_dev)) {
e87cc472 JP	293	if (IN_DEV_LOG_MARTIANS(in_dev))
	294	net_info_ratelimited("source route option %pI4 -> %pI4\n",
	295	&iph->saddr,
	296	&iph->daddr);
d245407e TG	297	goto drop;
d245407e TG	298	}
d245407e TG	299	}
	300
	301	if (ip_options_rcv_srr(skb))
	302	goto drop;
	303	}
	304
6a91395f	305	return false;
d245407e	306	drop:
6a91395f	307	return true;
d245407e TG	308	}
d245407e TG	309
6648bd7e	310	int sysctl_ip_early_demux __read_mostly = 1;
c7109986	311	EXPORT_SYMBOL(sysctl_ip_early_demux);
6648bd7e	312
7026b1dd	313	static int ip_rcv_finish(struct sock sk, struct sk_buff skb)
1da177e4	314	{
eddc9ec5	315	const struct iphdr *iph = ip_hdr(skb);
5506b54b	316	struct rtable *rt;
1da177e4	317
51456b29	318	if (sysctl_ip_early_demux && !skb_dst(skb) && !skb->sk) {
160eb5a6 DM	319	const struct net_protocol *ipprot;
	320	int protocol = iph->protocol;
	321
160eb5a6	322	ipprot = rcu_dereference(inet_protos[protocol]);
9cb429d6	323	if (ipprot && ipprot->early_demux) {
160eb5a6	324	ipprot->early_demux(skb);
9cb429d6 ED	325	/* must reload iph, skb->head might have changed */
	326	iph = ip_hdr(skb);
	327	}
160eb5a6 DM	328	}
160eb5a6 DM	329
1da177e4 LT	330	/*
	331	* Initialise the virtual path cache for the packet. It describes
	332	* how the packet travels inside Linux networking.
e905a9ed	333	*/
160eb5a6	334	if (!skb_dst(skb)) {
c6cffba4 DM	335	int err = ip_route_input_noref(skb, iph->daddr, iph->saddr,
c6cffba4 DM	336	iph->tos, skb->dev);
160eb5a6 DM	337	if (unlikely(err)) {
	338	if (err == -EXDEV)
	339	NET_INC_STATS_BH(dev_net(skb->dev),
	340	LINUX_MIB_IPRPFILTER);
	341	goto drop;
2c2910a4	342	}
1da177e4 LT	343	}
1da177e4 LT	344
c7066f70	345	#ifdef CONFIG_IP_ROUTE_CLASSID
adf30907	346	if (unlikely(skb_dst(skb)->tclassid)) {
7a9b2d59	347	struct ip_rt_acct *st = this_cpu_ptr(ip_rt_acct);
adf30907	348	u32 idx = skb_dst(skb)->tclassid;
1da177e4	349	st[idx&0xFF].o_packets++;
fd3f8c4c	350	st[idx&0xFF].o_bytes += skb->len;
1da177e4	351	st[(idx>>16)&0xFF].i_packets++;
fd3f8c4c	352	st[(idx>>16)&0xFF].i_bytes += skb->len;
1da177e4 LT	353	}
	354	#endif
	355
d245407e TG	356	if (iph->ihl > 5 && ip_rcv_options(skb))
d245407e TG	357	goto drop;
1da177e4	358
511c3f92	359	rt = skb_rtable(skb);
edf391ff	360	if (rt->rt_type == RTN_MULTICAST) {
d8d1f30b	361	IP_UPD_PO_STATS_BH(dev_net(rt->dst.dev), IPSTATS_MIB_INMCAST,
edf391ff NH	362	skb->len);
edf391ff NH	363	} else if (rt->rt_type == RTN_BROADCAST)
d8d1f30b	364	IP_UPD_PO_STATS_BH(dev_net(rt->dst.dev), IPSTATS_MIB_INBCAST,
edf391ff	365	skb->len);
5506b54b	366
1da177e4 LT	367	return dst_input(skb);
1da177e4 LT	368
1da177e4	369	drop:
e905a9ed YH	370	kfree_skb(skb);
e905a9ed YH	371	return NET_RX_DROP;
1da177e4 LT	372	}
	373
	374	/*
	375	* Main IP Receive routine.
e905a9ed	376	*/
f2ccd8fa	377	int ip_rcv(struct sk_buff skb, struct net_device dev, struct packet_type pt, struct net_device orig_dev)
1da177e4	378	{
b71d1d42	379	const struct iphdr *iph;
58615242	380	u32 len;
1da177e4 LT	381
	382	/* When the interface is in promisc. mode, drop all the crap
	383	* that it receives, do not try to analyse it.
	384	*/
	385	if (skb->pkt_type == PACKET_OTHERHOST)
	386	goto drop;
	387
edf391ff NH	388
edf391ff NH	389	IP_UPD_PO_STATS_BH(dev_net(dev), IPSTATS_MIB_IN, skb->len);
1da177e4	390
51456b29 IM	391	skb = skb_share_check(skb, GFP_ATOMIC);
51456b29 IM	392	if (!skb) {
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	415
1f07d03e ED	416	BUILD_BUG_ON(IPSTATS_MIB_ECT1PKTS != IPSTATS_MIB_NOECTPKTS + INET_ECN_ECT_1);
	417	BUILD_BUG_ON(IPSTATS_MIB_ECT0PKTS != IPSTATS_MIB_NOECTPKTS + INET_ECN_ECT_0);
	418	BUILD_BUG_ON(IPSTATS_MIB_CEPKTS != IPSTATS_MIB_NOECTPKTS + INET_ECN_CE);
	419	IP_ADD_STATS_BH(dev_net(dev),
	420	IPSTATS_MIB_NOECTPKTS + (iph->tos & INET_ECN_MASK),
	421	max_t(unsigned short, 1, skb_shinfo(skb)->gso_segs));
	422
1da177e4 LT	423	if (!pskb_may_pull(skb, iph->ihl*4))
	424	goto inhdr_error;
	425
eddc9ec5	426	iph = ip_hdr(skb);
1da177e4	427
e9c60422	428	if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
6a5dc9e5	429	goto csum_error;
1da177e4	430
58615242	431	len = ntohs(iph->tot_len);
704aed53	432	if (skb->len < len) {
7c73a6fa	433	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INTRUNCATEDPKTS);
704aed53 MC	434	goto drop;
704aed53 MC	435	} else if (len < (iph->ihl*4))
58615242	436	goto inhdr_error;
1da177e4	437
58615242 TG	438	/* Our transport medium may have padded the buffer out. Now we know it
	439	* is IP we can trim to the true length of the frame.
	440	* Note this now means skb->len holds ntohs(iph->tot_len).
	441	*/
	442	if (pskb_trim_rcsum(skb, len)) {
7c73a6fa	443	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
58615242	444	goto drop;
1da177e4 LT	445	}
1da177e4 LT	446
21d1196a ED	447	skb->transport_header = skb->network_header + iph->ihl*4;
21d1196a ED	448
53602f92	449	/* Remove any debris in the socket control block */
d569f1d7	450	memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
53602f92	451
71f9dacd HX	452	/* Must drop socket now because of tproxy. */
	453	skb_orphan(skb);
	454
7026b1dd DM	455	return NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, NULL, skb,
7026b1dd DM	456	dev, NULL,
1da177e4 LT	457	ip_rcv_finish);
1da177e4 LT	458
6a5dc9e5 ED	459	csum_error:
6a5dc9e5 ED	460	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_CSUMERRORS);
1da177e4	461	inhdr_error:
7c73a6fa	462	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INHDRERRORS);
1da177e4	463	drop:
e905a9ed	464	kfree_skb(skb);
1da177e4	465	out:
e905a9ed	466	return NET_RX_DROP;
1da177e4	467	}