[mirror_ubuntu-hirsute-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>
#include <net/dst_metadata.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_valid_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>
f38a9eb1	149	#include <net/dst_metadata.h>
1da177e4	150
1da177e4	151	/*
66018506	152	* Process Router Attention IP option (RFC 2113)
e905a9ed	153	*/
ba57b4db	154	bool ip_call_ra_chain(struct sk_buff *skb)
1da177e4 LT	155	{
1da177e4 LT	156	struct ip_ra_chain *ra;
eddc9ec5	157	u8 protocol = ip_hdr(skb)->protocol;
1da177e4	158	struct sock *last = NULL;
cb84663e	159	struct net_device *dev = skb->dev;
1da177e4	160
66018506	161	for (ra = rcu_dereference(ip_ra_chain); ra; ra = rcu_dereference(ra->next)) {
1da177e4 LT	162	struct sock *sk = ra->sk;
	163
	164	/* If socket is bound to an interface, only report
	165	* the packet if it came from that interface.
	166	*/
c720c7e8	167	if (sk && inet_sk(sk)->inet_num == protocol &&
1da177e4	168	(!sk->sk_bound_dev_if \|\|
cb84663e	169	sk->sk_bound_dev_if == dev->ifindex) &&
09ad9bc7	170	net_eq(sock_net(sk), dev_net(dev))) {
56f8a75c	171	if (ip_is_fragment(ip_hdr(skb))) {
66018506	172	if (ip_defrag(skb, IP_DEFRAG_CALL_RA_CHAIN))
ba57b4db	173	return true;
1da177e4 LT	174	}
	175	if (last) {
	176	struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
	177	if (skb2)
	178	raw_rcv(last, skb2);
	179	}
	180	last = sk;
	181	}
	182	}
	183
	184	if (last) {
	185	raw_rcv(last, skb);
ba57b4db	186	return true;
1da177e4	187	}
ba57b4db	188	return false;
1da177e4 LT	189	}
1da177e4 LT	190
7026b1dd	191	static int ip_local_deliver_finish(struct sock sk, struct sk_buff skb)
1da177e4	192	{
c346dca1	193	struct net *net = dev_net(skb->dev);
f145049a	194
21d1196a	195	__skb_pull(skb, skb_network_header_len(skb));
1da177e4 LT	196
	197	rcu_read_lock();
	198	{
eddc9ec5	199	int protocol = ip_hdr(skb)->protocol;
32613090	200	const struct net_protocol *ipprot;
f9242b6b	201	int raw;
1da177e4 LT	202
1da177e4 LT	203	resubmit:
7bc54c90	204	raw = raw_local_deliver(skb, protocol);
1da177e4	205
f9242b6b	206	ipprot = rcu_dereference(inet_protos[protocol]);
00db4124	207	if (ipprot) {
1da177e4 LT	208	int ret;
1da177e4 LT	209
b59c2701 PM	210	if (!ipprot->no_policy) {
	211	if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
	212	kfree_skb(skb);
	213	goto out;
	214	}
	215	nf_reset(skb);
1da177e4 LT	216	}
	217	ret = ipprot->handler(skb);
	218	if (ret < 0) {
	219	protocol = -ret;
	220	goto resubmit;
	221	}
7c73a6fa	222	IP_INC_STATS_BH(net, IPSTATS_MIB_INDELIVERS);
1da177e4	223	} else {
7bc54c90	224	if (!raw) {
1da177e4	225	if (xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
7c73a6fa	226	IP_INC_STATS_BH(net, IPSTATS_MIB_INUNKNOWNPROTOS);
1da177e4 LT	227	icmp_send(skb, ICMP_DEST_UNREACH,
	228	ICMP_PROT_UNREACH, 0);
	229	}
d8c6f4b9 NH	230	kfree_skb(skb);
d8c6f4b9 NH	231	} else {
7c73a6fa	232	IP_INC_STATS_BH(net, IPSTATS_MIB_INDELIVERS);
d8c6f4b9 NH	233	consume_skb(skb);
d8c6f4b9 NH	234	}
1da177e4 LT	235	}
	236	}
	237	out:
	238	rcu_read_unlock();
	239
	240	return 0;
	241	}
	242
	243	/*
	244	* Deliver IP Packets to the higher protocol layers.
e905a9ed	245	*/
1da177e4 LT	246	int ip_local_deliver(struct sk_buff *skb)
	247	{
	248	/*
	249	* Reassemble IP fragments.
	250	*/
	251
56f8a75c	252	if (ip_is_fragment(ip_hdr(skb))) {
776c729e	253	if (ip_defrag(skb, IP_DEFRAG_LOCAL_DELIVER))
1da177e4 LT	254	return 0;
	255	}
	256
7026b1dd DM	257	return NF_HOOK(NFPROTO_IPV4, NF_INET_LOCAL_IN, NULL, skb,
7026b1dd DM	258	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
7026b1dd	314	static int ip_rcv_finish(struct sock sk, struct sk_buff skb)
1da177e4	315	{
eddc9ec5	316	const struct iphdr *iph = ip_hdr(skb);
5506b54b	317	struct rtable *rt;
1da177e4	318
51456b29	319	if (sysctl_ip_early_demux && !skb_dst(skb) && !skb->sk) {
160eb5a6 DM	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	*/
f38a9eb1	335	if (!skb_valid_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	391
51456b29 IM	392	skb = skb_share_check(skb, GFP_ATOMIC);
51456b29 IM	393	if (!skb) {
7c73a6fa	394	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
1da177e4 LT	395	goto out;
	396	}
	397
	398	if (!pskb_may_pull(skb, sizeof(struct iphdr)))
	399	goto inhdr_error;
	400
eddc9ec5	401	iph = ip_hdr(skb);
1da177e4 LT	402
1da177e4 LT	403	/*
c67fa027	404	* RFC1122: 3.2.1.2 MUST silently discard any IP frame that fails the checksum.
1da177e4 LT	405	*
	406	* Is the datagram acceptable?
	407	*
	408	* 1. Length at least the size of an ip header
	409	* 2. Version of 4
	410	* 3. Checksums correctly. [Speed optimisation for later, skip loopback checksums]
	411	* 4. Doesn't have a bogus length
	412	*/
	413
	414	if (iph->ihl < 5 \|\| iph->version != 4)
58615242	415	goto inhdr_error;
1da177e4	416
1f07d03e ED	417	BUILD_BUG_ON(IPSTATS_MIB_ECT1PKTS != IPSTATS_MIB_NOECTPKTS + INET_ECN_ECT_1);
	418	BUILD_BUG_ON(IPSTATS_MIB_ECT0PKTS != IPSTATS_MIB_NOECTPKTS + INET_ECN_ECT_0);
	419	BUILD_BUG_ON(IPSTATS_MIB_CEPKTS != IPSTATS_MIB_NOECTPKTS + INET_ECN_CE);
	420	IP_ADD_STATS_BH(dev_net(dev),
	421	IPSTATS_MIB_NOECTPKTS + (iph->tos & INET_ECN_MASK),
	422	max_t(unsigned short, 1, skb_shinfo(skb)->gso_segs));
	423
1da177e4 LT	424	if (!pskb_may_pull(skb, iph->ihl*4))
	425	goto inhdr_error;
	426
eddc9ec5	427	iph = ip_hdr(skb);
1da177e4	428
e9c60422	429	if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
6a5dc9e5	430	goto csum_error;
1da177e4	431
58615242	432	len = ntohs(iph->tot_len);
704aed53	433	if (skb->len < len) {
7c73a6fa	434	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INTRUNCATEDPKTS);
704aed53 MC	435	goto drop;
704aed53 MC	436	} else if (len < (iph->ihl*4))
58615242	437	goto inhdr_error;
1da177e4	438
58615242 TG	439	/* Our transport medium may have padded the buffer out. Now we know it
	440	* is IP we can trim to the true length of the frame.
	441	* Note this now means skb->len holds ntohs(iph->tot_len).
	442	*/
	443	if (pskb_trim_rcsum(skb, len)) {
7c73a6fa	444	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
58615242	445	goto drop;
1da177e4 LT	446	}
1da177e4 LT	447
21d1196a ED	448	skb->transport_header = skb->network_header + iph->ihl*4;
21d1196a ED	449
53602f92	450	/* Remove any debris in the socket control block */
d569f1d7	451	memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
53602f92	452
71f9dacd HX	453	/* Must drop socket now because of tproxy. */
	454	skb_orphan(skb);
	455
7026b1dd DM	456	return NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, NULL, skb,
7026b1dd DM	457	dev, NULL,
1da177e4 LT	458	ip_rcv_finish);
1da177e4 LT	459
6a5dc9e5 ED	460	csum_error:
6a5dc9e5 ED	461	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_CSUMERRORS);
1da177e4	462	inhdr_error:
7c73a6fa	463	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INHDRERRORS);
1da177e4	464	drop:
e905a9ed	465	kfree_skb(skb);
1da177e4	466	out:
e905a9ed	467	return NET_RX_DROP;
1da177e4	468	}