patch-1.3.36 linux/net/ipv4/ip_input.c

• Lines: 614
• Date: Tue Oct 17 13:42:37 1995
• Orig file: v1.3.35/linux/net/ipv4/ip_input.c
• Orig date: Thu Jan 1 02:00:00 1970

diff -u --recursive --new-file v1.3.35/linux/net/ipv4/ip_input.c linux/net/ipv4/ip_input.c
@@ -0,0 +1,613 @@
+/*
+ * 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:	@(#)ip.c	1.0.16b	9/1/93
+ *
+ * Authors:	Ross Biro, <bir7@leland.Stanford.Edu>
+ *		Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
+ *		Donald Becker, <becker@super.org>
+ *		Alan Cox, <Alan.Cox@linux.org>
+ *		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 didnt 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
+ *
+ *  
+ *
+ * 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.
+ *
+ *		FIXME: copy frag 0 iph to qp->iph
+ *
+ *		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/segment.h>
+#include <asm/system.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <linux/string.h>
+#include <linux/errno.h>
+#include <linux/config.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 <linux/proc_fs.h>
+#include <linux/stat.h>
+
+#include <net/snmp.h>
+#include <net/ip.h>
+#include <net/protocol.h>
+#include <net/route.h>
+#include <net/tcp.h>
+#include <net/udp.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/igmp.h>
+#include <linux/ip_fw.h>
+#include <linux/firewall.h>
+#include <linux/mroute.h>
+#include <net/netlink.h>
+
+extern int last_retran;
+extern void sort_send(struct sock *sk);
+
+#define min(a,b)	((a)<(b)?(a):(b))
+
+/*
+ *	SNMP management statistics
+ */
+
+#ifdef CONFIG_IP_FORWARD
+struct ip_mib ip_statistics={1,64,};	/* Forwarding=Yes, Default TTL=64 */
+#else
+struct ip_mib ip_statistics={2,64,};	/* Forwarding=No, Default TTL=64 */
+#endif
+
+/*
+ *	Handle the issuing of an ioctl() request
+ *	for the ip device. This is scheduled to
+ *	disappear
+ */
+
+int ip_ioctl(struct sock *sk, int cmd, unsigned long arg)
+{
+	switch(cmd)
+	{
+		default:
+			return(-EINVAL);
+	}
+}
+
+
+
+/*
+ *	This function receives all incoming IP datagrams.
+ *
+ *	On entry skb->data points to the start of the IP header and
+ *	the MAC header has been removed.
+ */
+
+int ip_rcv(struct sk_buff *skb, struct device *dev, struct packet_type *pt)
+{
+	struct iphdr *iph = skb->h.iph;
+	struct sock *raw_sk=NULL;
+	unsigned char hash;
+	unsigned char flag = 0;
+	struct inet_protocol *ipprot;
+	int brd=IS_MYADDR;
+	struct options * opt = NULL;
+	int is_frag=0;
+#ifdef CONFIG_FIREWALL
+	int err;
+#endif	
+#ifdef CONFIG_IP_MROUTE
+	int mroute_pkt=0;
+#endif	
+
+#ifdef CONFIG_NET_IPV6
+	/* 
+	 *	Intercept IPv6 frames. We dump ST-II and invalid types just below..
+	 */
+	 
+	if(iph->version == 6)
+		return ipv6_rcv(skb,dev,pt);
+#endif		
+
+	ip_statistics.IpInReceives++;
+
+	/*
+	 *	Tag the ip header of this packet so we can find it
+	 */
+
+	skb->ip_hdr = iph;
+
+	/*
+	 *	RFC1122: 3.1.2.2 MUST silently discard any IP frame that fails the checksum.
+	 *	RFC1122: 3.1.2.3 MUST discard a frame with invalid source address [NEEDS FIXING].
+	 *
+	 *	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
+	 *	(5.	We ought to check for IP multicast addresses and undefined types.. does this matter ?)
+	 */
+
+	if (skb->len<sizeof(struct iphdr) || iph->ihl<5 || iph->version != 4 || ip_fast_csum((unsigned char *)iph, iph->ihl) !=0
+		|| skb->len < ntohs(iph->tot_len))
+	{
+		ip_statistics.IpInHdrErrors++;
+		kfree_skb(skb, FREE_WRITE);
+		return(0);
+	}
+
+	/*
+	 *	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).
+	 */
+
+	skb_trim(skb,ntohs(iph->tot_len));
+
+	if (iph->ihl > 5) 
+	{
+		skb->ip_summed = 0;
+		if (ip_options_compile(NULL, skb))
+			return(0);
+		opt = (struct options*)skb->proto_priv;
+#ifdef CONFIG_IP_NOSR
+		if (opt->srr) 
+		{
+			kfree_skb(skb, FREE_READ);
+			return -EINVAL;
+		}
+#endif					
+	}
+	
+	/*
+	 *	See if the firewall wants to dispose of the packet. 
+	 */
+
+#ifdef	CONFIG_FIREWALL
+	
+	if ((err=call_in_firewall(PF_INET, skb, iph))<FW_ACCEPT)
+	{
+		if(err==FW_REJECT)
+			icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0, dev);
+		kfree_skb(skb, FREE_WRITE);
+		return 0;	
+	}
+
+#endif
+	
+	/*
+	 *	Remember if the frame is fragmented.
+	 */
+	 
+	if(iph->frag_off)
+	{
+		if (iph->frag_off & htons(IP_MF))
+			is_frag|=1;
+		/*
+		 *	Last fragment ?
+		 */
+	
+		if (iph->frag_off & htons(IP_OFFSET))
+			is_frag|=2;
+	}
+	
+	/*
+	 *	Do any IP forwarding required.  chk_addr() is expensive -- avoid it someday.
+	 *
+	 *	This is inefficient. While finding out if it is for us we could also compute
+	 *	the routing table entry. This is where the great unified cache theory comes
+	 *	in as and when someone implements it
+	 *
+	 *	For most hosts over 99% of packets match the first conditional
+	 *	and don't go via ip_chk_addr. Note: brd is set to IS_MYADDR at
+	 *	function entry.
+	 */
+
+	if ( iph->daddr == skb->dev->pa_addr || (brd = ip_chk_addr(iph->daddr)) != 0)
+	{
+	        if (opt && opt->srr) 
+	        {
+			int srrspace, srrptr;
+			__u32 nexthop;
+			unsigned char * optptr = ((unsigned char *)iph) + opt->srr;
+
+			if (brd != IS_MYADDR || skb->pkt_type != PACKET_HOST) 
+			{
+				kfree_skb(skb, FREE_WRITE);
+				return 0;
+			}
+
+			for ( srrptr=optptr[2], srrspace = optptr[1];
+			      srrptr <= srrspace;
+			      srrptr += 4
+			     ) 
+			{
+				int brd2;
+				if (srrptr + 3 > srrspace) 
+				{
+					icmp_send(skb, ICMP_PARAMETERPROB, 0, opt->srr+2,
+						  skb->dev);
+					kfree_skb(skb, FREE_WRITE);
+					return 0;
+				}
+				memcpy(&nexthop, &optptr[srrptr-1], 4);
+				if ((brd2 = ip_chk_addr(nexthop)) == 0)
+					break;
+				if (brd2 != IS_MYADDR) 
+				{
+
+					/*
+					 *	ANK: should we implement weak tunneling of multicasts?
+					 *	Are they obsolete? DVMRP specs (RFC-1075) is old enough...
+					 *	[They are obsolete]
+					 */
+					kfree_skb(skb, FREE_WRITE);
+					return -EINVAL;
+				}
+			}
+			if (srrptr <= srrspace) 
+			{
+				opt->srr_is_hit = 1;
+				opt->is_changed = 1;
+#ifdef CONFIG_IP_FORWARD
+				if (ip_forward(skb, dev, is_frag, nexthop))
+					kfree_skb(skb, FREE_WRITE);
+#else
+				ip_statistics.IpInAddrErrors++;
+				kfree_skb(skb, FREE_WRITE);
+#endif
+				return 0;
+			}
+		}
+
+#ifdef CONFIG_IP_MULTICAST	
+		if(!(dev->flags&IFF_ALLMULTI) && brd==IS_MULTICAST && iph->daddr!=IGMP_ALL_HOSTS && !(dev->flags&IFF_LOOPBACK))
+		{
+			/*
+			 *	Check it is for one of our groups
+			 */
+			struct ip_mc_list *ip_mc=dev->ip_mc_list;
+			do
+			{
+				if(ip_mc==NULL)
+				{	
+					kfree_skb(skb, FREE_WRITE);
+					return 0;
+				}
+				if(ip_mc->multiaddr==iph->daddr)
+					break;
+				ip_mc=ip_mc->next;
+			}
+			while(1);
+		}
+#endif
+
+#ifdef CONFIG_IP_MASQUERADE
+		/*
+		 * Do we need to de-masquerade this fragment?
+		 */
+		if (ip_fw_demasquerade(skb)) 
+		{
+			struct iphdr *iph=skb->h.iph;
+			if (ip_forward(skb, dev, is_frag|4, iph->daddr))
+				kfree_skb(skb, FREE_WRITE);
+			return(0);
+		}
+#endif
+
+		/*
+		 *	Account for the packet
+		 */
+ 
+#ifdef CONFIG_IP_ACCT
+		ip_fw_chk(iph,dev,ip_acct_chain,IP_FW_F_ACCEPT,1);
+#endif	
+
+		/*
+		 *	Reassemble IP fragments.
+		 */
+
+		if(is_frag)
+		{
+			/* Defragment. Obtain the complete packet if there is one */
+			skb=ip_defrag(iph,skb,dev);
+			if(skb==NULL)
+				return 0;
+			skb->dev = dev;
+			iph=skb->h.iph;
+		}
+
+		/*
+		 *	Point into the IP datagram, just past the header.
+		 */
+
+		skb->ip_hdr = iph;
+		skb->h.raw += iph->ihl*4;
+
+#ifdef CONFIG_IP_MROUTE		
+		/*
+		 *	Check the state on multicast routing (multicast and not 224.0.0.z)
+		 */
+		 
+		if(brd==IS_MULTICAST && (iph->daddr&htonl(0xFFFFFF00))!=htonl(0xE0000000))
+			mroute_pkt=1;
+
+#endif
+		/*
+		 *	Deliver to raw sockets. This is fun as to avoid copies we want to make no surplus copies.
+		 *
+		 *	RFC 1122: SHOULD pass TOS value up to the transport layer.
+		 */
+ 
+		hash = iph->protocol & (SOCK_ARRAY_SIZE-1);
+
+		/* 
+		 *	If there maybe a raw socket we must check - if not we don't care less 
+		 */
+		 
+		if((raw_sk=raw_prot.sock_array[hash])!=NULL)
+		{
+			struct sock *sknext=NULL;
+			struct sk_buff *skb1;
+			raw_sk=get_sock_raw(raw_sk, iph->protocol,  iph->saddr, iph->daddr);
+			if(raw_sk)	/* Any raw sockets */
+			{
+				do
+				{
+					/* Find the next */
+					sknext=get_sock_raw(raw_sk->next, iph->protocol, iph->saddr, iph->daddr);
+					if(sknext)
+						skb1=skb_clone(skb, GFP_ATOMIC);
+					else
+						break;	/* One pending raw socket left */
+					if(skb1)
+						raw_rcv(raw_sk, skb1, dev, iph->saddr,iph->daddr);
+					raw_sk=sknext;
+				}
+				while(raw_sk!=NULL);
+				
+				/*
+				 *	Here either raw_sk is the last raw socket, or NULL if none 
+				 */
+				 
+				/*
+				 *	We deliver to the last raw socket AFTER the protocol checks as it avoids a surplus copy 
+				 */
+			}
+		}
+	
+		/*
+		 *	skb->h.raw now points at the protocol beyond the IP header.
+		 */
+	
+		hash = iph->protocol & (MAX_INET_PROTOS -1);
+		for (ipprot = (struct inet_protocol *)inet_protos[hash];ipprot != NULL;ipprot=(struct inet_protocol *)ipprot->next)
+		{
+			struct sk_buff *skb2;
+	
+			if (ipprot->protocol != iph->protocol)
+				continue;
+		       /*
+			* 	See if we need to make a copy of it.  This will
+			* 	only be set if more than one protocol wants it.
+			* 	and then not for the last one. If there is a pending
+			*	raw delivery wait for that
+			*/
+	
+#ifdef CONFIG_IP_MROUTE
+			if (ipprot->copy || raw_sk || mroute_pkt)
+#else	
+			if (ipprot->copy || raw_sk)
+#endif			
+			{
+				skb2 = skb_clone(skb, GFP_ATOMIC);
+				if(skb2==NULL)
+					continue;
+			}
+			else
+			{
+				skb2 = skb;
+			}
+			flag = 1;
+
+		       /*
+			*	Pass on the datagram to each protocol that wants it,
+			*	based on the datagram protocol.  We should really
+			*	check the protocol handler's return values here...
+			*/
+
+			ipprot->handler(skb2, dev, opt, iph->daddr,
+				(ntohs(iph->tot_len) - (iph->ihl * 4)),
+				iph->saddr, 0, ipprot);
+		}
+
+		/*
+		 *	All protocols checked.
+		 *	If this packet was a broadcast, we may *not* reply to it, since that
+		 *	causes (proven, grin) ARP storms and a leakage of memory (i.e. all
+		 *	ICMP reply messages get queued up for transmission...)
+		 */
+
+#ifdef CONFIG_IP_MROUTE		 
+		/*
+		 *	Forward the last copy to the multicast router. If
+		 *	there is a pending raw deliery however make a copy
+		 *	and forward that.
+		 */
+		 
+		if(mroute_pkt)
+		{
+			flag=1;
+			if(raw_sk==NULL)
+				ipmr_forward(skb, is_frag);
+			else
+			{
+				struct sk_buff *skb2=skb_clone(skb, GFP_ATOMIC);
+				if(skb2)
+				{
+					skb2->free=1;
+					ipmr_forward(skb2, is_frag);
+				}
+			}
+		}
+#endif		
+
+		if(raw_sk!=NULL)	/* Shift to last raw user */
+			raw_rcv(raw_sk, skb, dev, iph->saddr, iph->daddr);
+		else if (!flag)		/* Free and report errors */
+		{
+			if (brd != IS_BROADCAST && brd!=IS_MULTICAST)
+				icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PROT_UNREACH, 0, dev);	
+			kfree_skb(skb, FREE_WRITE);
+		}
+
+		return(0);
+	}
+
+	/*
+	 *	Do any unicast IP forwarding required.
+	 */
+	
+	/*
+	 *	Don't forward multicast or broadcast frames.
+	 */
+
+	if(skb->pkt_type!=PACKET_HOST || brd==IS_BROADCAST)
+	{
+		kfree_skb(skb,FREE_WRITE);
+		return 0;
+	}
+
+	/*
+	 *	The packet is for another target. Forward the frame
+	 */
+
+#ifdef CONFIG_IP_FORWARD
+	if (opt && opt->is_strictroute) 
+	{
+	      icmp_send(skb, ICMP_PARAMETERPROB, 0, 16, skb->dev);
+	      kfree_skb(skb, FREE_WRITE);
+	      return -1;
+	}
+	if (ip_forward(skb, dev, is_frag, iph->daddr))
+		kfree_skb(skb, FREE_WRITE);
+#else
+/*	printk("Machine %lx tried to use us as a forwarder to %lx but we have forwarding disabled!\n",
+			iph->saddr,iph->daddr);*/
+	ip_statistics.IpInAddrErrors++;
+	kfree_skb(skb, FREE_WRITE);
+#endif
+	return(0);
+}
+	
+