| 1 |
1275 |
phoenix |
/*
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| 2 |
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* INET An implementation of the TCP/IP protocol suite for the LINUX
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| 3 |
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* operating system. INET is implemented using the BSD Socket
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| 4 |
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* interface as the means of communication with the user level.
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*
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* The Internet Protocol (IP) module.
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*
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* Version: $Id: ip_input.c,v 1.1.1.1 2004-04-15 01:13:18 phoenix Exp $
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*
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| 10 |
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* Authors: Ross Biro, <bir7@leland.Stanford.Edu>
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* Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
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* Donald Becker, <becker@super.org>
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* Alan Cox, <Alan.Cox@linux.org>
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* Richard Underwood
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* Stefan Becker, <stefanb@yello.ping.de>
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* Jorge Cwik, <jorge@laser.satlink.net>
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* Arnt Gulbrandsen, <agulbra@nvg.unit.no>
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*
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*
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* Fixes:
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* Alan Cox : Commented a couple of minor bits of surplus code
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* Alan Cox : Undefining IP_FORWARD doesn't include the code
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* (just stops a compiler warning).
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* Alan Cox : Frames with >=MAX_ROUTE record routes, strict routes or loose routes
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* are junked rather than corrupting things.
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* Alan Cox : Frames to bad broadcast subnets are dumped
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* We used to process them non broadcast and
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* boy could that cause havoc.
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* Alan Cox : ip_forward sets the free flag on the
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* new frame it queues. Still crap because
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* it copies the frame but at least it
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* doesn't eat memory too.
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* Alan Cox : Generic queue code and memory fixes.
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* Fred Van Kempen : IP fragment support (borrowed from NET2E)
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* Gerhard Koerting: Forward fragmented frames correctly.
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* Gerhard Koerting: Fixes to my fix of the above 8-).
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* Gerhard Koerting: IP interface addressing fix.
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* Linus Torvalds : More robustness checks
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* Alan Cox : Even more checks: Still not as robust as it ought to be
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* Alan Cox : Save IP header pointer for later
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* Alan Cox : ip option setting
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* Alan Cox : Use ip_tos/ip_ttl settings
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* Alan Cox : Fragmentation bogosity removed
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* (Thanks to Mark.Bush@prg.ox.ac.uk)
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* Dmitry Gorodchanin : Send of a raw packet crash fix.
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* Alan Cox : Silly ip bug when an overlength
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* fragment turns up. Now frees the
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* queue.
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* Linus Torvalds/ : Memory leakage on fragmentation
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* Alan Cox : handling.
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* Gerhard Koerting: Forwarding uses IP priority hints
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* Teemu Rantanen : Fragment problems.
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* Alan Cox : General cleanup, comments and reformat
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* Alan Cox : SNMP statistics
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* Alan Cox : BSD address rule semantics. Also see
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* UDP as there is a nasty checksum issue
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| 57 |
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* if you do things the wrong way.
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* Alan Cox : Always defrag, moved IP_FORWARD to the config.in file
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* Alan Cox : IP options adjust sk->priority.
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| 60 |
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* Pedro Roque : Fix mtu/length error in ip_forward.
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* Alan Cox : Avoid ip_chk_addr when possible.
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* Richard Underwood : IP multicasting.
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* Alan Cox : Cleaned up multicast handlers.
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* Alan Cox : RAW sockets demultiplex in the BSD style.
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* Gunther Mayer : Fix the SNMP reporting typo
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* Alan Cox : Always in group 224.0.0.1
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* Pauline Middelink : Fast ip_checksum update when forwarding
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* Masquerading support.
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* Alan Cox : Multicast loopback error for 224.0.0.1
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* Alan Cox : IP_MULTICAST_LOOP option.
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* Alan Cox : Use notifiers.
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* Bjorn Ekwall : Removed ip_csum (from slhc.c too)
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* Bjorn Ekwall : Moved ip_fast_csum to ip.h (inline!)
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* Stefan Becker : Send out ICMP HOST REDIRECT
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* Arnt Gulbrandsen : ip_build_xmit
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* Alan Cox : Per socket routing cache
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* Alan Cox : Fixed routing cache, added header cache.
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* Alan Cox : Loopback didn't work right in original ip_build_xmit - fixed it.
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* Alan Cox : Only send ICMP_REDIRECT if src/dest are the same net.
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* Alan Cox : Incoming IP option handling.
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* Alan Cox : Set saddr on raw output frames as per BSD.
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* Alan Cox : Stopped broadcast source route explosions.
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* Alan Cox : Can disable source routing
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* Takeshi Sone : Masquerading didn't work.
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* Dave Bonn,Alan Cox : Faster IP forwarding whenever possible.
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* Alan Cox : Memory leaks, tramples, misc debugging.
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* Alan Cox : Fixed multicast (by popular demand 8))
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* Alan Cox : Fixed forwarding (by even more popular demand 8))
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* Alan Cox : Fixed SNMP statistics [I think]
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* Gerhard Koerting : IP fragmentation forwarding fix
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* Alan Cox : Device lock against page fault.
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* Alan Cox : IP_HDRINCL facility.
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* Werner Almesberger : Zero fragment bug
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* Alan Cox : RAW IP frame length bug
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* Alan Cox : Outgoing firewall on build_xmit
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* A.N.Kuznetsov : IP_OPTIONS support throughout the kernel
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* Alan Cox : Multicast routing hooks
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* Jos Vos : Do accounting *before* call_in_firewall
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* Willy Konynenberg : Transparent proxying support
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*
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*
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*
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* To Fix:
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* IP fragmentation wants rewriting cleanly. The RFC815 algorithm is much more efficient
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* and could be made very efficient with the addition of some virtual memory hacks to permit
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* the allocation of a buffer that can then be 'grown' by twiddling page tables.
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* Output fragmentation wants updating along with the buffer management to use a single
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* interleaved copy algorithm so that fragmenting has a one copy overhead. Actual packet
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* output should probably do its own fragmentation at the UDP/RAW layer. TCP shouldn't cause
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* fragmentation anyway.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <asm/system.h>
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#include <linux/types.h>
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#include <linux/kernel.h>
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#include <linux/string.h>
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| 122 |
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#include <linux/errno.h>
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#include <linux/config.h>
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| 124 |
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| 125 |
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#include <linux/net.h>
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| 126 |
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#include <linux/socket.h>
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| 127 |
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#include <linux/sockios.h>
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| 128 |
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#include <linux/in.h>
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| 129 |
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#include <linux/inet.h>
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| 130 |
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#include <linux/netdevice.h>
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| 131 |
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#include <linux/etherdevice.h>
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| 133 |
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#include <net/snmp.h>
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| 134 |
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#include <net/ip.h>
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#include <net/protocol.h>
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| 136 |
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#include <net/route.h>
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#include <linux/skbuff.h>
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#include <net/sock.h>
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| 139 |
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#include <net/arp.h>
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| 140 |
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#include <net/icmp.h>
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| 141 |
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#include <net/raw.h>
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| 142 |
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#include <net/checksum.h>
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| 143 |
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#include <linux/netfilter_ipv4.h>
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| 144 |
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#include <linux/mroute.h>
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| 145 |
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#include <linux/netlink.h>
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| 146 |
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| 147 |
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/*
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| 148 |
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* SNMP management statistics
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| 149 |
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*/
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| 150 |
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| 151 |
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struct ip_mib ip_statistics[NR_CPUS*2];
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| 152 |
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| 153 |
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/*
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| 154 |
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* Process Router Attention IP option
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*/
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| 156 |
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int ip_call_ra_chain(struct sk_buff *skb)
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{
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| 158 |
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struct ip_ra_chain *ra;
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| 159 |
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u8 protocol = skb->nh.iph->protocol;
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| 160 |
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struct sock *last = NULL;
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| 161 |
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| 162 |
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read_lock(&ip_ra_lock);
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| 163 |
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for (ra = ip_ra_chain; ra; ra = ra->next) {
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struct sock *sk = ra->sk;
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| 165 |
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| 166 |
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/* If socket is bound to an interface, only report
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* the packet if it came from that interface.
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*/
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if (sk && sk->num == protocol
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&& ((sk->bound_dev_if == 0)
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|| (sk->bound_dev_if == skb->dev->ifindex))) {
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if (skb->nh.iph->frag_off & htons(IP_MF|IP_OFFSET)) {
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skb = ip_defrag(skb);
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| 174 |
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if (skb == NULL) {
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| 175 |
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read_unlock(&ip_ra_lock);
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| 176 |
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return 1;
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| 177 |
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}
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| 178 |
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}
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| 179 |
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if (last) {
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| 180 |
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struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
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| 181 |
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if (skb2)
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| 182 |
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raw_rcv(last, skb2);
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| 183 |
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}
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| 184 |
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last = sk;
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| 185 |
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}
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| 186 |
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}
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| 187 |
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| 188 |
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if (last) {
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| 189 |
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raw_rcv(last, skb);
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| 190 |
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read_unlock(&ip_ra_lock);
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| 191 |
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return 1;
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| 192 |
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}
|
| 193 |
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read_unlock(&ip_ra_lock);
|
| 194 |
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return 0;
|
| 195 |
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}
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| 196 |
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|
| 197 |
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/* Handle this out of line, it is rare. */
|
| 198 |
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static int ip_run_ipprot(struct sk_buff *skb, struct iphdr *iph,
|
| 199 |
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struct inet_protocol *ipprot, int force_copy)
|
| 200 |
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{
|
| 201 |
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int ret = 0;
|
| 202 |
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|
| 203 |
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do {
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| 204 |
|
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if (ipprot->protocol == iph->protocol) {
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| 205 |
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struct sk_buff *skb2 = skb;
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| 206 |
|
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if (ipprot->copy || force_copy)
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| 207 |
|
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skb2 = skb_clone(skb, GFP_ATOMIC);
|
| 208 |
|
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if(skb2 != NULL) {
|
| 209 |
|
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ret = 1;
|
| 210 |
|
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ipprot->handler(skb2);
|
| 211 |
|
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}
|
| 212 |
|
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}
|
| 213 |
|
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ipprot = (struct inet_protocol *) ipprot->next;
|
| 214 |
|
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} while(ipprot != NULL);
|
| 215 |
|
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|
| 216 |
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return ret;
|
| 217 |
|
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}
|
| 218 |
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|
| 219 |
|
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static inline int ip_local_deliver_finish(struct sk_buff *skb)
|
| 220 |
|
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{
|
| 221 |
|
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int ihl = skb->nh.iph->ihl*4;
|
| 222 |
|
|
|
| 223 |
|
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#ifdef CONFIG_NETFILTER_DEBUG
|
| 224 |
|
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nf_debug_ip_local_deliver(skb);
|
| 225 |
|
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#endif /*CONFIG_NETFILTER_DEBUG*/
|
| 226 |
|
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|
| 227 |
|
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__skb_pull(skb, ihl);
|
| 228 |
|
|
|
| 229 |
|
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#ifdef CONFIG_NETFILTER
|
| 230 |
|
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/* Free reference early: we don't need it any more, and it may
|
| 231 |
|
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hold ip_conntrack module loaded indefinitely. */
|
| 232 |
|
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nf_conntrack_put(skb->nfct);
|
| 233 |
|
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skb->nfct = NULL;
|
| 234 |
|
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#endif /*CONFIG_NETFILTER*/
|
| 235 |
|
|
|
| 236 |
|
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/* Point into the IP datagram, just past the header. */
|
| 237 |
|
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skb->h.raw = skb->data;
|
| 238 |
|
|
|
| 239 |
|
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{
|
| 240 |
|
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/* Note: See raw.c and net/raw.h, RAWV4_HTABLE_SIZE==MAX_INET_PROTOS */
|
| 241 |
|
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int protocol = skb->nh.iph->protocol;
|
| 242 |
|
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int hash = protocol & (MAX_INET_PROTOS - 1);
|
| 243 |
|
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struct sock *raw_sk = raw_v4_htable[hash];
|
| 244 |
|
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struct inet_protocol *ipprot;
|
| 245 |
|
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int flag;
|
| 246 |
|
|
|
| 247 |
|
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/* If there maybe a raw socket we must check - if not we
|
| 248 |
|
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* don't care less
|
| 249 |
|
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*/
|
| 250 |
|
|
if(raw_sk != NULL)
|
| 251 |
|
|
raw_sk = raw_v4_input(skb, skb->nh.iph, hash);
|
| 252 |
|
|
|
| 253 |
|
|
ipprot = (struct inet_protocol *) inet_protos[hash];
|
| 254 |
|
|
flag = 0;
|
| 255 |
|
|
if(ipprot != NULL) {
|
| 256 |
|
|
if(raw_sk == NULL &&
|
| 257 |
|
|
ipprot->next == NULL &&
|
| 258 |
|
|
ipprot->protocol == protocol) {
|
| 259 |
|
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int ret;
|
| 260 |
|
|
|
| 261 |
|
|
/* Fast path... */
|
| 262 |
|
|
ret = ipprot->handler(skb);
|
| 263 |
|
|
|
| 264 |
|
|
return ret;
|
| 265 |
|
|
} else {
|
| 266 |
|
|
flag = ip_run_ipprot(skb, skb->nh.iph, ipprot, (raw_sk != NULL));
|
| 267 |
|
|
}
|
| 268 |
|
|
}
|
| 269 |
|
|
|
| 270 |
|
|
/* All protocols checked.
|
| 271 |
|
|
* If this packet was a broadcast, we may *not* reply to it, since that
|
| 272 |
|
|
* causes (proven, grin) ARP storms and a leakage of memory (i.e. all
|
| 273 |
|
|
* ICMP reply messages get queued up for transmission...)
|
| 274 |
|
|
*/
|
| 275 |
|
|
if(raw_sk != NULL) { /* Shift to last raw user */
|
| 276 |
|
|
raw_rcv(raw_sk, skb);
|
| 277 |
|
|
sock_put(raw_sk);
|
| 278 |
|
|
} else if (!flag) { /* Free and report errors */
|
| 279 |
|
|
icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PROT_UNREACH, 0);
|
| 280 |
|
|
kfree_skb(skb);
|
| 281 |
|
|
}
|
| 282 |
|
|
}
|
| 283 |
|
|
|
| 284 |
|
|
return 0;
|
| 285 |
|
|
}
|
| 286 |
|
|
|
| 287 |
|
|
/*
|
| 288 |
|
|
* Deliver IP Packets to the higher protocol layers.
|
| 289 |
|
|
*/
|
| 290 |
|
|
int ip_local_deliver(struct sk_buff *skb)
|
| 291 |
|
|
{
|
| 292 |
|
|
/*
|
| 293 |
|
|
* Reassemble IP fragments.
|
| 294 |
|
|
*/
|
| 295 |
|
|
|
| 296 |
|
|
if (skb->nh.iph->frag_off & htons(IP_MF|IP_OFFSET)) {
|
| 297 |
|
|
skb = ip_defrag(skb);
|
| 298 |
|
|
if (!skb)
|
| 299 |
|
|
return 0;
|
| 300 |
|
|
}
|
| 301 |
|
|
|
| 302 |
|
|
return NF_HOOK(PF_INET, NF_IP_LOCAL_IN, skb, skb->dev, NULL,
|
| 303 |
|
|
ip_local_deliver_finish);
|
| 304 |
|
|
}
|
| 305 |
|
|
|
| 306 |
|
|
static inline int ip_rcv_finish(struct sk_buff *skb)
|
| 307 |
|
|
{
|
| 308 |
|
|
struct net_device *dev = skb->dev;
|
| 309 |
|
|
struct iphdr *iph = skb->nh.iph;
|
| 310 |
|
|
|
| 311 |
|
|
/*
|
| 312 |
|
|
* Initialise the virtual path cache for the packet. It describes
|
| 313 |
|
|
* how the packet travels inside Linux networking.
|
| 314 |
|
|
*/
|
| 315 |
|
|
if (skb->dst == NULL) {
|
| 316 |
|
|
if (ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, dev))
|
| 317 |
|
|
goto drop;
|
| 318 |
|
|
}
|
| 319 |
|
|
|
| 320 |
|
|
#ifdef CONFIG_NET_CLS_ROUTE
|
| 321 |
|
|
if (skb->dst->tclassid) {
|
| 322 |
|
|
struct ip_rt_acct *st = ip_rt_acct + 256*smp_processor_id();
|
| 323 |
|
|
u32 idx = skb->dst->tclassid;
|
| 324 |
|
|
st[idx&0xFF].o_packets++;
|
| 325 |
|
|
st[idx&0xFF].o_bytes+=skb->len;
|
| 326 |
|
|
st[(idx>>16)&0xFF].i_packets++;
|
| 327 |
|
|
st[(idx>>16)&0xFF].i_bytes+=skb->len;
|
| 328 |
|
|
}
|
| 329 |
|
|
#endif
|
| 330 |
|
|
|
| 331 |
|
|
if (iph->ihl > 5) {
|
| 332 |
|
|
struct ip_options *opt;
|
| 333 |
|
|
|
| 334 |
|
|
/* It looks as overkill, because not all
|
| 335 |
|
|
IP options require packet mangling.
|
| 336 |
|
|
But it is the easiest for now, especially taking
|
| 337 |
|
|
into account that combination of IP options
|
| 338 |
|
|
and running sniffer is extremely rare condition.
|
| 339 |
|
|
--ANK (980813)
|
| 340 |
|
|
*/
|
| 341 |
|
|
|
| 342 |
|
|
if (skb_cow(skb, skb_headroom(skb)))
|
| 343 |
|
|
goto drop;
|
| 344 |
|
|
iph = skb->nh.iph;
|
| 345 |
|
|
|
| 346 |
|
|
if (ip_options_compile(NULL, skb))
|
| 347 |
|
|
goto inhdr_error;
|
| 348 |
|
|
|
| 349 |
|
|
opt = &(IPCB(skb)->opt);
|
| 350 |
|
|
if (opt->srr) {
|
| 351 |
|
|
struct in_device *in_dev = in_dev_get(dev);
|
| 352 |
|
|
if (in_dev) {
|
| 353 |
|
|
if (!IN_DEV_SOURCE_ROUTE(in_dev)) {
|
| 354 |
|
|
if (IN_DEV_LOG_MARTIANS(in_dev) && net_ratelimit())
|
| 355 |
|
|
printk(KERN_INFO "source route option %u.%u.%u.%u -> %u.%u.%u.%u\n",
|
| 356 |
|
|
NIPQUAD(iph->saddr), NIPQUAD(iph->daddr));
|
| 357 |
|
|
in_dev_put(in_dev);
|
| 358 |
|
|
goto drop;
|
| 359 |
|
|
}
|
| 360 |
|
|
in_dev_put(in_dev);
|
| 361 |
|
|
}
|
| 362 |
|
|
if (ip_options_rcv_srr(skb))
|
| 363 |
|
|
goto drop;
|
| 364 |
|
|
}
|
| 365 |
|
|
}
|
| 366 |
|
|
|
| 367 |
|
|
return skb->dst->input(skb);
|
| 368 |
|
|
|
| 369 |
|
|
inhdr_error:
|
| 370 |
|
|
IP_INC_STATS_BH(IpInHdrErrors);
|
| 371 |
|
|
drop:
|
| 372 |
|
|
kfree_skb(skb);
|
| 373 |
|
|
return NET_RX_DROP;
|
| 374 |
|
|
}
|
| 375 |
|
|
|
| 376 |
|
|
/*
|
| 377 |
|
|
* Main IP Receive routine.
|
| 378 |
|
|
*/
|
| 379 |
|
|
int ip_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt)
|
| 380 |
|
|
{
|
| 381 |
|
|
struct iphdr *iph;
|
| 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 |
|
|
|
| 389 |
|
|
IP_INC_STATS_BH(IpInReceives);
|
| 390 |
|
|
|
| 391 |
|
|
if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)
|
| 392 |
|
|
goto out;
|
| 393 |
|
|
|
| 394 |
|
|
if (!pskb_may_pull(skb, sizeof(struct iphdr)))
|
| 395 |
|
|
goto inhdr_error;
|
| 396 |
|
|
|
| 397 |
|
|
iph = skb->nh.iph;
|
| 398 |
|
|
|
| 399 |
|
|
/*
|
| 400 |
|
|
* RFC1122: 3.1.2.2 MUST silently discard any IP frame that fails the checksum.
|
| 401 |
|
|
*
|
| 402 |
|
|
* Is the datagram acceptable?
|
| 403 |
|
|
*
|
| 404 |
|
|
* 1. Length at least the size of an ip header
|
| 405 |
|
|
* 2. Version of 4
|
| 406 |
|
|
* 3. Checksums correctly. [Speed optimisation for later, skip loopback checksums]
|
| 407 |
|
|
* 4. Doesn't have a bogus length
|
| 408 |
|
|
*/
|
| 409 |
|
|
|
| 410 |
|
|
if (iph->ihl < 5 || iph->version != 4)
|
| 411 |
|
|
goto inhdr_error;
|
| 412 |
|
|
|
| 413 |
|
|
if (!pskb_may_pull(skb, iph->ihl*4))
|
| 414 |
|
|
goto inhdr_error;
|
| 415 |
|
|
|
| 416 |
|
|
iph = skb->nh.iph;
|
| 417 |
|
|
|
| 418 |
|
|
if (ip_fast_csum((u8 *)iph, iph->ihl) != 0)
|
| 419 |
|
|
goto inhdr_error;
|
| 420 |
|
|
|
| 421 |
|
|
{
|
| 422 |
|
|
__u32 len = ntohs(iph->tot_len);
|
| 423 |
|
|
if (skb->len < len || len < (iph->ihl<<2))
|
| 424 |
|
|
goto inhdr_error;
|
| 425 |
|
|
|
| 426 |
|
|
/* Our transport medium may have padded the buffer out. Now we know it
|
| 427 |
|
|
* is IP we can trim to the true length of the frame.
|
| 428 |
|
|
* Note this now means skb->len holds ntohs(iph->tot_len).
|
| 429 |
|
|
*/
|
| 430 |
|
|
if (skb->len > len) {
|
| 431 |
|
|
__pskb_trim(skb, len);
|
| 432 |
|
|
if (skb->ip_summed == CHECKSUM_HW)
|
| 433 |
|
|
skb->ip_summed = CHECKSUM_NONE;
|
| 434 |
|
|
}
|
| 435 |
|
|
}
|
| 436 |
|
|
|
| 437 |
|
|
return NF_HOOK(PF_INET, NF_IP_PRE_ROUTING, skb, dev, NULL,
|
| 438 |
|
|
ip_rcv_finish);
|
| 439 |
|
|
|
| 440 |
|
|
inhdr_error:
|
| 441 |
|
|
IP_INC_STATS_BH(IpInHdrErrors);
|
| 442 |
|
|
drop:
|
| 443 |
|
|
kfree_skb(skb);
|
| 444 |
|
|
out:
|
| 445 |
|
|
return NET_RX_DROP;
|
| 446 |
|
|
}
|
| 447 |
|
|
|
