1 files changed, 431 insertions, 0 deletions

diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
new file mode 100644
index 000000000000..a0d0833034be
--- /dev/null
+++ b/net/ipv4/ip_input.c
@@ -0,0 +1,431 @@
+/*
+ * 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, <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 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;
+                }
+        }
+
+        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;
+
+#ifdef CONFIG_NETFILTER_DEBUG
+        nf_debug_ip_local_deliver(skb);
+#endif /*CONFIG_NETFILTER_DEBUG*/
+
+        __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);