[linux.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.
 *
 * Version:	$Id: ip_input.c,v 1.55 2002/01/12 07:39:45 davem Exp $
 *
 * Authors:	Ross Biro
 *		Fred N. van Kempen, <[email protected]>
 *		Donald Becker, <[email protected]>
 *		Alan Cox, <[email protected]>
 *		Richard Underwood
 *		Stefan Becker, <[email protected]>
 *		Jorge Cwik, <[email protected]>
 *		Arnt Gulbrandsen, <[email protected]>
 *		
 *
 * 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 [email protected])
 *		Dmitry Gorodchanin :	Send of a raw packet crash fix.
 *		Alan Cox	:	Silly ip bug when an overlength
 *					fragment turns up. Now frees the
 *					queue.
 *		Linus Torvalds/ :	Memory leakage on fragmentation
 *		Alan Cox	:	handling.
 *		Gerhard Koerting:	Forwarding uses IP priority hints
 *		Teemu Rantanen	:	Fragment problems.
 *		Alan Cox	:	General cleanup, comments and reformat
 *		Alan Cox	:	SNMP statistics
 *		Alan Cox	:	BSD address rule semantics. Also see
 *					UDP as there is a nasty checksum issue
 *					if you do things the wrong way.
 *		Alan Cox	:	Always defrag, moved IP_FORWARD to the config.in file
 *		Alan Cox	: 	IP options adjust sk->priority.
 *		Pedro Roque	:	Fix mtu/length error in ip_forward.
 *		Alan Cox	:	Avoid ip_chk_addr when possible.
 *	Richard Underwood	:	IP multicasting.
 *		Alan Cox	:	Cleaned up multicast handlers.
 *		Alan Cox	:	RAW sockets demultiplex in the BSD style.
 *		Gunther Mayer	:	Fix the SNMP reporting typo
 *		Alan Cox	:	Always in group 224.0.0.1
 *	Pauline Middelink	:	Fast ip_checksum update when forwarding
 *					Masquerading support.
 *		Alan Cox	:	Multicast loopback error for 224.0.0.1
 *		Alan Cox	:	IP_MULTICAST_LOOP option.
 *		Alan Cox	:	Use notifiers.
 *		Bjorn Ekwall	:	Removed ip_csum (from slhc.c too)
 *		Bjorn Ekwall	:	Moved ip_fast_csum to ip.h (inline!)
 *		Stefan Becker   :       Send out ICMP HOST REDIRECT
 *	Arnt Gulbrandsen	:	ip_build_xmit
 *		Alan Cox	:	Per socket routing cache
 *		Alan Cox	:	Fixed routing cache, added header cache.
 *		Alan Cox	:	Loopback didn't work right in original ip_build_xmit - fixed it.
 *		Alan Cox	:	Only send ICMP_REDIRECT if src/dest are the same net.
 *		Alan Cox	:	Incoming IP option handling.
 *		Alan Cox	:	Set saddr on raw output frames as per BSD.
 *		Alan Cox	:	Stopped broadcast source route explosions.
 *		Alan Cox	:	Can disable source routing
 *		Takeshi Sone    :	Masquerading didn't work.
 *	Dave Bonn,Alan Cox	:	Faster IP forwarding whenever possible.
 *		Alan Cox	:	Memory leaks, tramples, misc debugging.
 *		Alan Cox	:	Fixed multicast (by popular demand 8))
 *		Alan Cox	:	Fixed forwarding (by even more popular demand 8))
 *		Alan Cox	:	Fixed SNMP statistics [I think]
 *	Gerhard Koerting	:	IP fragmentation forwarding fix
 *		Alan Cox	:	Device lock against page fault.
 *		Alan Cox	:	IP_HDRINCL facility.
 *	Werner Almesberger	:	Zero fragment bug
 *		Alan Cox	:	RAW IP frame length bug
 *		Alan Cox	:	Outgoing firewall on build_xmit
 *		A.N.Kuznetsov	:	IP_OPTIONS support throughout the kernel
 *		Alan Cox	:	Multicast routing hooks
 *		Jos Vos		:	Do accounting *before* call_in_firewall
 *	Willy Konynenberg	:	Transparent proxying support
 *
 *  
 *
 * To Fix:
 *		IP fragmentation wants rewriting cleanly. The RFC815 algorithm is much more efficient
 *		and could be made very efficient with the addition of some virtual memory hacks to permit
 *		the allocation of a buffer that can then be 'grown' by twiddling page tables.
 *		Output fragmentation wants updating along with the buffer management to use a single 
 *		interleaved copy algorithm so that fragmenting has a one copy overhead. Actual packet
 *		output should probably do its own fragmentation at the UDP/RAW layer. TCP shouldn't cause
 *		fragmentation anyway.
 *
 *		This program is free software; you can redistribute it and/or
 *		modify it under the terms of the GNU General Public License
 *		as published by the Free Software Foundation; either version
 *		2 of the License, or (at your option) any later version.
 */

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

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

/*
 *	SNMP management statistics
 */

DEFINE_SNMP_STAT(struct ipstats_mib, ip_statistics);

/*
 *	Process Router Attention IP option
 */ 
int ip_call_ra_chain(struct sk_buff *skb)
{
	struct ip_ra_chain *ra;
	u8 protocol = skb->nh.iph->protocol;
	struct sock *last = NULL;

	read_lock(&ip_ra_lock);
	for (ra = ip_ra_chain; ra; ra = 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)->num == protocol &&
		    (!sk->sk_bound_dev_if ||
		     sk->sk_bound_dev_if == skb->dev->ifindex)) {
			if (skb->nh.iph->frag_off & htons(IP_MF|IP_OFFSET)) {
				skb = ip_defrag(skb, IP_DEFRAG_CALL_RA_CHAIN);
				if (skb == NULL) {
					read_unlock(&ip_ra_lock);
					return 1;
				}
			}
			if (last) {
				struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
				if (skb2)
					raw_rcv(last, skb2);
			}
			last = sk;
			nf_reset(skb);
		}
	}

	if (last) {
		raw_rcv(last, skb);
		read_unlock(&ip_ra_lock);
		return 1;
	}
	read_unlock(&ip_ra_lock);
	return 0;
}

static inline int ip_local_deliver_finish(struct sk_buff *skb)
{
	int ihl = skb->nh.iph->ihl*4;

	__skb_pull(skb, ihl);

	/* Free reference early: we don't need it any more, and it may
           hold ip_conntrack module loaded indefinitely. */
	nf_reset(skb);

        /* Point into the IP datagram, just past the header. */
        skb->h.raw = skb->data;

	rcu_read_lock();
	{
		/* Note: See raw.c and net/raw.h, RAWV4_HTABLE_SIZE==MAX_INET_PROTOS */
		int protocol = skb->nh.iph->protocol;
		int hash;
		struct sock *raw_sk;
		struct net_protocol *ipprot;

	resubmit:
		hash = protocol & (MAX_INET_PROTOS - 1);
		raw_sk = sk_head(&raw_v4_htable[hash]);

		/* If there maybe a raw socket we must check - if not we
		 * don't care less
		 */
		if (raw_sk)
			raw_v4_input(skb, skb->nh.iph, hash);

		if ((ipprot = rcu_dereference(inet_protos[hash])) != NULL) {
			int ret;

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

	return 0;
}

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

	if (skb->nh.iph->frag_off & htons(IP_MF|IP_OFFSET)) {
		skb = ip_defrag(skb, IP_DEFRAG_LOCAL_DELIVER);
		if (!skb)
			return 0;
	}

	return NF_HOOK(PF_INET, NF_IP_LOCAL_IN, skb, skb->dev, NULL,
		       ip_local_deliver_finish);
}

static inline int ip_rcv_finish(struct sk_buff *skb)
{
	struct net_device *dev = skb->dev;
	struct iphdr *iph = skb->nh.iph;

	/*
	 *	Initialise the virtual path cache for the packet. It describes
	 *	how the packet travels inside Linux networking.
	 */ 
	if (skb->dst == NULL) {
		if (ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, dev))
			goto drop; 
	}

#ifdef CONFIG_NET_CLS_ROUTE
	if (skb->dst->tclassid) {
		struct ip_rt_acct *st = ip_rt_acct + 256*smp_processor_id();
		u32 idx = skb->dst->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) {
		struct ip_options *opt;

		/* 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(IPSTATS_MIB_INDISCARDS);
			goto drop;
		}
		iph = skb->nh.iph;

		if (ip_options_compile(NULL, skb))
			goto inhdr_error;

		opt = &(IPCB(skb)->opt);
		if (opt->srr) {
			struct in_device *in_dev = in_dev_get(dev);
			if (in_dev) {
				if (!IN_DEV_SOURCE_ROUTE(in_dev)) {
					if (IN_DEV_LOG_MARTIANS(in_dev) && net_ratelimit())
						printk(KERN_INFO "source route option %u.%u.%u.%u -> %u.%u.%u.%u\n",
						       NIPQUAD(iph->saddr), NIPQUAD(iph->daddr));
					in_dev_put(in_dev);
					goto drop;
				}
				in_dev_put(in_dev);
			}
			if (ip_options_rcv_srr(skb))
				goto drop;
		}
	}

	return dst_input(skb);

inhdr_error:
	IP_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
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 iphdr *iph;

	/* 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_INC_STATS_BH(IPSTATS_MIB_INRECEIVES);

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

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

	iph = skb->nh.iph;

	/*
	 *	RFC1122: 3.1.2.2 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 = skb->nh.iph;

	if (ip_fast_csum((u8 *)iph, iph->ihl) != 0)
		goto inhdr_error; 

	{
		__u32 len = ntohs(iph->tot_len); 
		if (skb->len < len || len < (iph->ihl<<2))
			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(IPSTATS_MIB_INDISCARDS);
			goto drop;
		}
	}

	return NF_HOOK(PF_INET, NF_IP_PRE_ROUTING, skb, dev, NULL,
		       ip_rcv_finish);

inhdr_error:
	IP_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
drop:
        kfree_skb(skb);
out:
        return NET_RX_DROP;
}

EXPORT_SYMBOL(ip_rcv);
EXPORT_SYMBOL(ip_statistics);
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	*
	8	* Version: $Id: ip_input.c,v 1.55 2002/01/12 07:39:45 davem Exp $
	9	*
02c30a84	10	* Authors: Ross Biro
1da177e4 LT	11	* Fred N. van Kempen, <[email protected]>
	12	* Donald Becker, <[email protected]>
	13	* Alan Cox, <[email protected]>
	14	* Richard Underwood
	15	* Stefan Becker, <[email protected]>
	16	* Jorge Cwik, <[email protected]>
	17	* Arnt Gulbrandsen, <[email protected]>
	18	*
	19	*
	20	* Fixes:
	21	* Alan Cox : Commented a couple of minor bits of surplus code
	22	* Alan Cox : Undefining IP_FORWARD doesn't include the code
	23	* (just stops a compiler warning).
	24	* Alan Cox : Frames with >=MAX_ROUTE record routes, strict routes or loose routes
	25	* are junked rather than corrupting things.
	26	* Alan Cox : Frames to bad broadcast subnets are dumped
	27	* We used to process them non broadcast and
	28	* boy could that cause havoc.
	29	* Alan Cox : ip_forward sets the free flag on the
	30	* new frame it queues. Still crap because
	31	* it copies the frame but at least it
	32	* doesn't eat memory too.
	33	* Alan Cox : Generic queue code and memory fixes.
	34	* Fred Van Kempen : IP fragment support (borrowed from NET2E)
	35	* Gerhard Koerting: Forward fragmented frames correctly.
	36	* Gerhard Koerting: Fixes to my fix of the above 8-).
	37	* Gerhard Koerting: IP interface addressing fix.
	38	* Linus Torvalds : More robustness checks
	39	* Alan Cox : Even more checks: Still not as robust as it ought to be
	40	* Alan Cox : Save IP header pointer for later
	41	* Alan Cox : ip option setting
	42	* Alan Cox : Use ip_tos/ip_ttl settings
	43	* Alan Cox : Fragmentation bogosity removed
	44	* (Thanks to [email protected])
	45	* Dmitry Gorodchanin : Send of a raw packet crash fix.
	46	* Alan Cox : Silly ip bug when an overlength
	47	* fragment turns up. Now frees the
	48	* queue.
	49	* Linus Torvalds/ : Memory leakage on fragmentation
	50	* Alan Cox : handling.
	51	* Gerhard Koerting: Forwarding uses IP priority hints
	52	* Teemu Rantanen : Fragment problems.
	53	* Alan Cox : General cleanup, comments and reformat
	54	* Alan Cox : SNMP statistics
	55	* Alan Cox : BSD address rule semantics. Also see
	56	* UDP as there is a nasty checksum issue
	57	* if you do things the wrong way.
	58	* Alan Cox : Always defrag, moved IP_FORWARD to the config.in file
	59	* Alan Cox : IP options adjust sk->priority.
	60	* Pedro Roque : Fix mtu/length error in ip_forward.
	61	* Alan Cox : Avoid ip_chk_addr when possible.
	62	* Richard Underwood : IP multicasting.
	63	* Alan Cox : Cleaned up multicast handlers.
	64	* Alan Cox : RAW sockets demultiplex in the BSD style.
	65	* Gunther Mayer : Fix the SNMP reporting typo
	66	* Alan Cox : Always in group 224.0.0.1
	67	* Pauline Middelink : Fast ip_checksum update when forwarding
	68	* Masquerading support.
	69	* Alan Cox : Multicast loopback error for 224.0.0.1
	70	* Alan Cox : IP_MULTICAST_LOOP option.
	71	* Alan Cox : Use notifiers.
	72	* Bjorn Ekwall : Removed ip_csum (from slhc.c too)
	73	* Bjorn Ekwall : Moved ip_fast_csum to ip.h (inline!)
	74	* Stefan Becker : Send out ICMP HOST REDIRECT
75	* Arnt Gulbrandsen : ip_build_xmit
76	* Alan Cox : Per socket routing cache
77	* Alan Cox : Fixed routing cache, added header cache.
78	* Alan Cox : Loopback didn't work right in original ip_build_xmit - fixed it.
79	* Alan Cox : Only send ICMP_REDIRECT if src/dest are the same net.
80	* Alan Cox : Incoming IP option handling.
81	* Alan Cox : Set saddr on raw output frames as per BSD.
82	* Alan Cox : Stopped broadcast source route explosions.
83	* Alan Cox : Can disable source routing
84	* Takeshi Sone : Masquerading didn't work.
85	* Dave Bonn,Alan Cox : Faster IP forwarding whenever possible.
86	* Alan Cox : Memory leaks, tramples, misc debugging.
87	* Alan Cox : Fixed multicast (by popular demand 8))
88	* Alan Cox : Fixed forwarding (by even more popular demand 8))
89	* Alan Cox : Fixed SNMP statistics [I think]
90	* Gerhard Koerting : IP fragmentation forwarding fix
91	* Alan Cox : Device lock against page fault.
92	* Alan Cox : IP_HDRINCL facility.
93	* Werner Almesberger : Zero fragment bug
94	* Alan Cox : RAW IP frame length bug
95	* Alan Cox : Outgoing firewall on build_xmit
96	* A.N.Kuznetsov : IP_OPTIONS support throughout the kernel
97	* Alan Cox : Multicast routing hooks
98	* Jos Vos : Do accounting before call_in_firewall
99	* Willy Konynenberg : Transparent proxying support
100	*
101	*
102	*
103	* To Fix:
104	* IP fragmentation wants rewriting cleanly. The RFC815 algorithm is much more efficient
105	* and could be made very efficient with the addition of some virtual memory hacks to permit
106	* the allocation of a buffer that can then be 'grown' by twiddling page tables.
107	* Output fragmentation wants updating along with the buffer management to use a single
108	* interleaved copy algorithm so that fragmenting has a one copy overhead. Actual packet
109	* output should probably do its own fragmentation at the UDP/RAW layer. TCP shouldn't cause
110	* fragmentation anyway.
111	*
112	* This program is free software; you can redistribute it and/or
113	* modify it under the terms of the GNU General Public License
114	* as published by the Free Software Foundation; either version
115	* 2 of the License, or (at your option) any later version.
116	*/
117
118	#include <asm/system.h>
119	#include <linux/module.h>
120	#include <linux/types.h>
121	#include <linux/kernel.h>
122	#include <linux/string.h>
123	#include <linux/errno.h>
124	#include <linux/config.h>
125
126	#include <linux/net.h>
127	#include <linux/socket.h>
128	#include <linux/sockios.h>
129	#include <linux/in.h>
130	#include <linux/inet.h>
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
149	/*
150	* SNMP management statistics
151	*/
152
153	DEFINE_SNMP_STAT(struct ipstats_mib, ip_statistics);
154
155	/*
156	* Process Router Attention IP option
157	*/
158	int ip_call_ra_chain(struct sk_buff *skb)
159	{
160	struct ip_ra_chain *ra;
161	u8 protocol = skb->nh.iph->protocol;
162	struct sock *last = NULL;
163
164	read_lock(&ip_ra_lock);
165	for (ra = ip_ra_chain; ra; ra = ra->next) {
166	struct sock *sk = ra->sk;
167
168	/* If socket is bound to an interface, only report
169	* the packet if it came from that interface.
170	*/
171	if (sk && inet_sk(sk)->num == protocol &&
172	(!sk->sk_bound_dev_if \|\|
173	sk->sk_bound_dev_if == skb->dev->ifindex)) {
174	if (skb->nh.iph->frag_off & htons(IP_MF\|IP_OFFSET)) {
175	skb = ip_defrag(skb, IP_DEFRAG_CALL_RA_CHAIN);
176	if (skb == NULL) {
177	read_unlock(&ip_ra_lock);
178	return 1;
179	}
180	}
181	if (last) {
182	struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
183	if (skb2)
184	raw_rcv(last, skb2);
185	}
186	last = sk;
2715bcf9	187	nf_reset(skb);
1da177e4 LT	188	}
	189	}
	190
	191	if (last) {
	192	raw_rcv(last, skb);
	193	read_unlock(&ip_ra_lock);
	194	return 1;
	195	}
	196	read_unlock(&ip_ra_lock);
	197	return 0;
	198	}
	199
	200	static inline int ip_local_deliver_finish(struct sk_buff *skb)
	201	{
	202	int ihl = skb->nh.iph->ihl*4;
	203
1da177e4 LT	204	__skb_pull(skb, ihl);
	205
	206	/* Free reference early: we don't need it any more, and it may
	207	hold ip_conntrack module loaded indefinitely. */
	208	nf_reset(skb);
	209
	210	/* Point into the IP datagram, just past the header. */
	211	skb->h.raw = skb->data;
	212
	213	rcu_read_lock();
	214	{
	215	/* Note: See raw.c and net/raw.h, RAWV4_HTABLE_SIZE==MAX_INET_PROTOS */
	216	int protocol = skb->nh.iph->protocol;
	217	int hash;
	218	struct sock *raw_sk;
	219	struct net_protocol *ipprot;
	220
	221	resubmit:
	222	hash = protocol & (MAX_INET_PROTOS - 1);
	223	raw_sk = sk_head(&raw_v4_htable[hash]);
	224
	225	/* If there maybe a raw socket we must check - if not we
	226	* don't care less
	227	*/
	228	if (raw_sk)
	229	raw_v4_input(skb, skb->nh.iph, hash);
	230
	231	if ((ipprot = rcu_dereference(inet_protos[hash])) != NULL) {
	232	int ret;
	233
	234	if (!ipprot->no_policy &&
	235	!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
	236	kfree_skb(skb);
	237	goto out;
	238	}
	239	ret = ipprot->handler(skb);
	240	if (ret < 0) {
	241	protocol = -ret;
	242	goto resubmit;
	243	}
	244	IP_INC_STATS_BH(IPSTATS_MIB_INDELIVERS);
	245	} else {
	246	if (!raw_sk) {
	247	if (xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
	248	IP_INC_STATS_BH(IPSTATS_MIB_INUNKNOWNPROTOS);
	249	icmp_send(skb, ICMP_DEST_UNREACH,
	250	ICMP_PROT_UNREACH, 0);
	251	}
	252	} else
	253	IP_INC_STATS_BH(IPSTATS_MIB_INDELIVERS);
	254	kfree_skb(skb);
	255	}
	256	}
	257	out:
	258	rcu_read_unlock();
	259
	260	return 0;
	261	}
	262
	263	/*
	264	* Deliver IP Packets to the higher protocol layers.
	265	*/
	266	int ip_local_deliver(struct sk_buff *skb)
	267	{
268	/*
269	* Reassemble IP fragments.
270	*/
271
272	if (skb->nh.iph->frag_off & htons(IP_MF\|IP_OFFSET)) {
273	skb = ip_defrag(skb, IP_DEFRAG_LOCAL_DELIVER);
274	if (!skb)
275	return 0;
276	}
277
278	return NF_HOOK(PF_INET, NF_IP_LOCAL_IN, skb, skb->dev, NULL,
279	ip_local_deliver_finish);
280	}
281
282	static inline int ip_rcv_finish(struct sk_buff *skb)
283	{
284	struct net_device *dev = skb->dev;
285	struct iphdr *iph = skb->nh.iph;
286
287	/*
288	* Initialise the virtual path cache for the packet. It describes
289	* how the packet travels inside Linux networking.
290	*/
291	if (skb->dst == NULL) {
292	if (ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, dev))
293	goto drop;
294	}
295
296	#ifdef CONFIG_NET_CLS_ROUTE
297	if (skb->dst->tclassid) {
298	struct ip_rt_acct st = ip_rt_acct + 256smp_processor_id();
299	u32 idx = skb->dst->tclassid;
300	st[idx&0xFF].o_packets++;
301	st[idx&0xFF].o_bytes+=skb->len;
302	st[(idx>>16)&0xFF].i_packets++;
303	st[(idx>>16)&0xFF].i_bytes+=skb->len;
304	}
305	#endif
306
307	if (iph->ihl > 5) {
308	struct ip_options *opt;
309
310	/* It looks as overkill, because not all
311	IP options require packet mangling.
312	But it is the easiest for now, especially taking
313	into account that combination of IP options
314	and running sniffer is extremely rare condition.
315	--ANK (980813)
316	*/
317
318	if (skb_cow(skb, skb_headroom(skb))) {
319	IP_INC_STATS_BH(IPSTATS_MIB_INDISCARDS);
320	goto drop;
321	}
322	iph = skb->nh.iph;
323
324	if (ip_options_compile(NULL, skb))
325	goto inhdr_error;
326
327	opt = &(IPCB(skb)->opt);
328	if (opt->srr) {
329	struct in_device *in_dev = in_dev_get(dev);
330	if (in_dev) {
331	if (!IN_DEV_SOURCE_ROUTE(in_dev)) {
332	if (IN_DEV_LOG_MARTIANS(in_dev) && net_ratelimit())
333	printk(KERN_INFO "source route option %u.%u.%u.%u -> %u.%u.%u.%u\n",
334	NIPQUAD(iph->saddr), NIPQUAD(iph->daddr));
335	in_dev_put(in_dev);
336	goto drop;
337	}
338	in_dev_put(in_dev);
339	}
340	if (ip_options_rcv_srr(skb))
341	goto drop;
342	}
343	}
344
345	return dst_input(skb);
346
347	inhdr_error:
348	IP_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
349	drop:
350	kfree_skb(skb);
351	return NET_RX_DROP;
352	}
353
354	/*
355	* Main IP Receive routine.
356	*/
357	int ip_rcv(struct sk_buff skb, struct net_device dev, struct packet_type *pt)
358	{
359	struct iphdr *iph;
360
361	/* When the interface is in promisc. mode, drop all the crap
362	* that it receives, do not try to analyse it.
363	*/
364	if (skb->pkt_type == PACKET_OTHERHOST)
365	goto drop;
366
367	IP_INC_STATS_BH(IPSTATS_MIB_INRECEIVES);
368
369	if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL) {
370	IP_INC_STATS_BH(IPSTATS_MIB_INDISCARDS);
371	goto out;
372	}
373
374	if (!pskb_may_pull(skb, sizeof(struct iphdr)))
375	goto inhdr_error;
376
377	iph = skb->nh.iph;
378
379	/*
380	* RFC1122: 3.1.2.2 MUST silently discard any IP frame that fails the checksum.
381	*
382	* Is the datagram acceptable?
383	*
384	* 1. Length at least the size of an ip header
385	* 2. Version of 4
386	* 3. Checksums correctly. [Speed optimisation for later, skip loopback checksums]
387	* 4. Doesn't have a bogus length
388	*/
389
390	if (iph->ihl < 5 \|\| iph->version != 4)
391	goto inhdr_error;
392
393	if (!pskb_may_pull(skb, iph->ihl*4))
394	goto inhdr_error;
395
396	iph = skb->nh.iph;
397
398	if (ip_fast_csum((u8 *)iph, iph->ihl) != 0)
399	goto inhdr_error;
400
401	{
402	__u32 len = ntohs(iph->tot_len);
403	if (skb->len < len \|\| len < (iph->ihl<<2))
404	goto inhdr_error;
405
406	/* Our transport medium may have padded the buffer out. Now we know it
407	* is IP we can trim to the true length of the frame.
408	* Note this now means skb->len holds ntohs(iph->tot_len).
409	*/
410	if (pskb_trim_rcsum(skb, len)) {
411	IP_INC_STATS_BH(IPSTATS_MIB_INDISCARDS);
412	goto drop;
413	}
414	}
415
416	return NF_HOOK(PF_INET, NF_IP_PRE_ROUTING, skb, dev, NULL,
417	ip_rcv_finish);
418
419	inhdr_error:
420	IP_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
421	drop:
422	kfree_skb(skb);
423	out:
424	return NET_RX_DROP;
425	}
426
427	EXPORT_SYMBOL(ip_rcv);
428	EXPORT_SYMBOL(ip_statistics);