468 строки
14 KiB
C
468 строки
14 KiB
C
/*
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* INET An implementation of the TCP/IP protocol suite for the LINUX
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* operating system. INET is implemented using the BSD Socket
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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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* Authors: Ross Biro
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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@lxorguk.ukuu.org.uk>
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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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* 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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* 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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#define pr_fmt(fmt) "IPv4: " fmt
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#include <linux/module.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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#include <linux/errno.h>
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#include <linux/slab.h>
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#include <linux/net.h>
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#include <linux/socket.h>
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#include <linux/sockios.h>
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#include <linux/in.h>
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#include <linux/inet.h>
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#include <linux/inetdevice.h>
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#include <linux/netdevice.h>
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#include <linux/etherdevice.h>
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#include <net/snmp.h>
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#include <net/ip.h>
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#include <net/protocol.h>
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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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#include <net/arp.h>
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#include <net/icmp.h>
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#include <net/raw.h>
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#include <net/checksum.h>
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#include <net/inet_ecn.h>
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#include <linux/netfilter_ipv4.h>
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#include <net/xfrm.h>
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#include <linux/mroute.h>
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#include <linux/netlink.h>
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/*
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* Process Router Attention IP option (RFC 2113)
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*/
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bool ip_call_ra_chain(struct sk_buff *skb)
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{
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struct ip_ra_chain *ra;
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u8 protocol = ip_hdr(skb)->protocol;
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struct sock *last = NULL;
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struct net_device *dev = skb->dev;
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for (ra = rcu_dereference(ip_ra_chain); ra; ra = rcu_dereference(ra->next)) {
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struct sock *sk = ra->sk;
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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 && inet_sk(sk)->inet_num == protocol &&
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(!sk->sk_bound_dev_if ||
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sk->sk_bound_dev_if == dev->ifindex) &&
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net_eq(sock_net(sk), dev_net(dev))) {
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if (ip_is_fragment(ip_hdr(skb))) {
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if (ip_defrag(skb, IP_DEFRAG_CALL_RA_CHAIN))
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return true;
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}
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if (last) {
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struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
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if (skb2)
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raw_rcv(last, skb2);
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}
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last = sk;
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}
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}
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if (last) {
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raw_rcv(last, skb);
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return true;
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}
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return false;
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}
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static int ip_local_deliver_finish(struct sock *sk, struct sk_buff *skb)
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{
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struct net *net = dev_net(skb->dev);
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__skb_pull(skb, skb_network_header_len(skb));
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rcu_read_lock();
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{
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int protocol = ip_hdr(skb)->protocol;
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const struct net_protocol *ipprot;
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int raw;
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resubmit:
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raw = raw_local_deliver(skb, protocol);
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ipprot = rcu_dereference(inet_protos[protocol]);
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if (ipprot) {
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int ret;
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if (!ipprot->no_policy) {
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if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
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kfree_skb(skb);
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goto out;
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}
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nf_reset(skb);
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}
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ret = ipprot->handler(skb);
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if (ret < 0) {
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protocol = -ret;
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goto resubmit;
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}
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IP_INC_STATS_BH(net, IPSTATS_MIB_INDELIVERS);
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} else {
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if (!raw) {
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if (xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
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IP_INC_STATS_BH(net, IPSTATS_MIB_INUNKNOWNPROTOS);
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icmp_send(skb, ICMP_DEST_UNREACH,
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ICMP_PROT_UNREACH, 0);
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}
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kfree_skb(skb);
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} else {
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IP_INC_STATS_BH(net, IPSTATS_MIB_INDELIVERS);
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consume_skb(skb);
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}
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}
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}
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out:
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rcu_read_unlock();
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return 0;
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}
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/*
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* Deliver IP Packets to the higher protocol layers.
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*/
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int ip_local_deliver(struct sk_buff *skb)
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{
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/*
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* Reassemble IP fragments.
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*/
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if (ip_is_fragment(ip_hdr(skb))) {
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if (ip_defrag(skb, IP_DEFRAG_LOCAL_DELIVER))
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return 0;
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}
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return NF_HOOK(NFPROTO_IPV4, NF_INET_LOCAL_IN, NULL, skb,
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skb->dev, NULL,
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ip_local_deliver_finish);
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}
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static inline bool ip_rcv_options(struct sk_buff *skb)
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{
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struct ip_options *opt;
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const struct iphdr *iph;
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struct net_device *dev = skb->dev;
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/* It looks as overkill, because not all
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IP options require packet mangling.
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But it is the easiest for now, especially taking
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into account that combination of IP options
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and running sniffer is extremely rare condition.
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--ANK (980813)
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*/
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if (skb_cow(skb, skb_headroom(skb))) {
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IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
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goto drop;
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}
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iph = ip_hdr(skb);
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opt = &(IPCB(skb)->opt);
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opt->optlen = iph->ihl*4 - sizeof(struct iphdr);
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if (ip_options_compile(dev_net(dev), opt, skb)) {
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IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INHDRERRORS);
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goto drop;
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}
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if (unlikely(opt->srr)) {
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struct in_device *in_dev = __in_dev_get_rcu(dev);
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if (in_dev) {
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if (!IN_DEV_SOURCE_ROUTE(in_dev)) {
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if (IN_DEV_LOG_MARTIANS(in_dev))
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net_info_ratelimited("source route option %pI4 -> %pI4\n",
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&iph->saddr,
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&iph->daddr);
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goto drop;
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}
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}
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if (ip_options_rcv_srr(skb))
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goto drop;
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}
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return false;
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drop:
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return true;
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}
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int sysctl_ip_early_demux __read_mostly = 1;
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EXPORT_SYMBOL(sysctl_ip_early_demux);
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static int ip_rcv_finish(struct sock *sk, struct sk_buff *skb)
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{
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const struct iphdr *iph = ip_hdr(skb);
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struct rtable *rt;
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if (sysctl_ip_early_demux && !skb_dst(skb) && !skb->sk) {
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const struct net_protocol *ipprot;
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int protocol = iph->protocol;
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ipprot = rcu_dereference(inet_protos[protocol]);
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if (ipprot && ipprot->early_demux) {
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ipprot->early_demux(skb);
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/* must reload iph, skb->head might have changed */
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iph = ip_hdr(skb);
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}
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}
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/*
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* Initialise the virtual path cache for the packet. It describes
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* how the packet travels inside Linux networking.
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*/
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if (!skb_dst(skb)) {
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int err = ip_route_input_noref(skb, iph->daddr, iph->saddr,
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iph->tos, skb->dev);
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if (unlikely(err)) {
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if (err == -EXDEV)
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NET_INC_STATS_BH(dev_net(skb->dev),
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LINUX_MIB_IPRPFILTER);
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goto drop;
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}
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}
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#ifdef CONFIG_IP_ROUTE_CLASSID
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if (unlikely(skb_dst(skb)->tclassid)) {
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struct ip_rt_acct *st = this_cpu_ptr(ip_rt_acct);
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u32 idx = skb_dst(skb)->tclassid;
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st[idx&0xFF].o_packets++;
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st[idx&0xFF].o_bytes += skb->len;
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st[(idx>>16)&0xFF].i_packets++;
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st[(idx>>16)&0xFF].i_bytes += skb->len;
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}
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#endif
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if (iph->ihl > 5 && ip_rcv_options(skb))
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goto drop;
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rt = skb_rtable(skb);
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if (rt->rt_type == RTN_MULTICAST) {
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IP_UPD_PO_STATS_BH(dev_net(rt->dst.dev), IPSTATS_MIB_INMCAST,
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skb->len);
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} else if (rt->rt_type == RTN_BROADCAST)
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IP_UPD_PO_STATS_BH(dev_net(rt->dst.dev), IPSTATS_MIB_INBCAST,
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skb->len);
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return dst_input(skb);
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drop:
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kfree_skb(skb);
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return NET_RX_DROP;
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}
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/*
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* Main IP Receive routine.
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*/
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int ip_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev)
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{
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const struct iphdr *iph;
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u32 len;
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/* When the interface is in promisc. mode, drop all the crap
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* that it receives, do not try to analyse it.
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*/
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if (skb->pkt_type == PACKET_OTHERHOST)
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goto drop;
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IP_UPD_PO_STATS_BH(dev_net(dev), IPSTATS_MIB_IN, skb->len);
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skb = skb_share_check(skb, GFP_ATOMIC);
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if (!skb) {
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IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
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goto out;
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}
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if (!pskb_may_pull(skb, sizeof(struct iphdr)))
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goto inhdr_error;
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iph = ip_hdr(skb);
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/*
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* RFC1122: 3.2.1.2 MUST silently discard any IP frame that fails the checksum.
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*
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* Is the datagram acceptable?
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*
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* 1. Length at least the size of an ip header
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* 2. Version of 4
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* 3. Checksums correctly. [Speed optimisation for later, skip loopback checksums]
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* 4. Doesn't have a bogus length
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*/
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if (iph->ihl < 5 || iph->version != 4)
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goto inhdr_error;
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BUILD_BUG_ON(IPSTATS_MIB_ECT1PKTS != IPSTATS_MIB_NOECTPKTS + INET_ECN_ECT_1);
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BUILD_BUG_ON(IPSTATS_MIB_ECT0PKTS != IPSTATS_MIB_NOECTPKTS + INET_ECN_ECT_0);
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BUILD_BUG_ON(IPSTATS_MIB_CEPKTS != IPSTATS_MIB_NOECTPKTS + INET_ECN_CE);
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IP_ADD_STATS_BH(dev_net(dev),
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IPSTATS_MIB_NOECTPKTS + (iph->tos & INET_ECN_MASK),
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max_t(unsigned short, 1, skb_shinfo(skb)->gso_segs));
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if (!pskb_may_pull(skb, iph->ihl*4))
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goto inhdr_error;
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iph = ip_hdr(skb);
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if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
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goto csum_error;
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len = ntohs(iph->tot_len);
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if (skb->len < len) {
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IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INTRUNCATEDPKTS);
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goto drop;
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} else if (len < (iph->ihl*4))
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goto inhdr_error;
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/* Our transport medium may have padded the buffer out. Now we know it
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* is IP we can trim to the true length of the frame.
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* Note this now means skb->len holds ntohs(iph->tot_len).
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*/
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if (pskb_trim_rcsum(skb, len)) {
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IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
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goto drop;
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}
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skb->transport_header = skb->network_header + iph->ihl*4;
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/* Remove any debris in the socket control block */
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memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
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/* Must drop socket now because of tproxy. */
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skb_orphan(skb);
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return NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, NULL, skb,
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dev, NULL,
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ip_rcv_finish);
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csum_error:
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IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_CSUMERRORS);
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inhdr_error:
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IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INHDRERRORS);
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drop:
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kfree_skb(skb);
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out:
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return NET_RX_DROP;
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}
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