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-rw-r--r--net/ipv4/ip_input.c452
1 files changed, 452 insertions, 0 deletions
diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
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+/*
+ * 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.
+ *
+ * Authors: Ross Biro
+ * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
+ * Donald Becker, <becker@super.org>
+ * Alan Cox, <alan@lxorguk.ukuu.org.uk>
+ * 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/slab.h>
+
+#include <linux/net.h>
+#include <linux/socket.h>
+#include <linux/sockios.h>
+#include <linux/in.h>
+#include <linux/inet.h>
+#include <linux/inetdevice.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>
+
+/*
+ * Process Router Attention IP option (RFC 2113)
+ */
+int ip_call_ra_chain(struct sk_buff *skb)
+{
+ struct ip_ra_chain *ra;
+ u8 protocol = ip_hdr(skb)->protocol;
+ struct sock *last = NULL;
+ struct net_device *dev = skb->dev;
+
+ for (ra = rcu_dereference(ip_ra_chain); ra; ra = rcu_dereference(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)->inet_num == protocol &&
+ (!sk->sk_bound_dev_if ||
+ sk->sk_bound_dev_if == dev->ifindex) &&
+ net_eq(sock_net(sk), dev_net(dev))) {
+ if (ip_hdr(skb)->frag_off & htons(IP_MF | IP_OFFSET)) {
+ if (ip_defrag(skb, IP_DEFRAG_CALL_RA_CHAIN))
+ 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);
+ return 1;
+ }
+ return 0;
+}
+
+static int ip_local_deliver_finish(struct sk_buff *skb)
+{
+ struct net *net = dev_net(skb->dev);
+
+ __skb_pull(skb, ip_hdrlen(skb));
+
+ /* Point into the IP datagram, just past the header. */
+ skb_reset_transport_header(skb);
+
+ rcu_read_lock();
+ {
+ int protocol = ip_hdr(skb)->protocol;
+ int hash, raw;
+ const struct net_protocol *ipprot;
+
+ resubmit:
+ raw = raw_local_deliver(skb, protocol);
+
+ hash = protocol & (MAX_INET_PROTOS - 1);
+ ipprot = rcu_dereference(inet_protos[hash]);
+ if (ipprot != NULL) {
+ int ret;
+
+ if (!net_eq(net, &init_net) && !ipprot->netns_ok) {
+ if (net_ratelimit())
+ printk("%s: proto %d isn't netns-ready\n",
+ __func__, protocol);
+ kfree_skb(skb);
+ goto out;
+ }
+
+ if (!ipprot->no_policy) {
+ if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
+ kfree_skb(skb);
+ goto out;
+ }
+ nf_reset(skb);
+ }
+ ret = ipprot->handler(skb);
+ if (ret < 0) {
+ protocol = -ret;
+ goto resubmit;
+ }
+ IP_INC_STATS_BH(net, IPSTATS_MIB_INDELIVERS);
+ } else {
+ if (!raw) {
+ if (xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
+ IP_INC_STATS_BH(net, IPSTATS_MIB_INUNKNOWNPROTOS);
+ icmp_send(skb, ICMP_DEST_UNREACH,
+ ICMP_PROT_UNREACH, 0);
+ }
+ } else
+ IP_INC_STATS_BH(net, 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 (ip_hdr(skb)->frag_off & htons(IP_MF | IP_OFFSET)) {
+ if (ip_defrag(skb, IP_DEFRAG_LOCAL_DELIVER))
+ return 0;
+ }
+
+ return NF_HOOK(NFPROTO_IPV4, NF_INET_LOCAL_IN, skb, skb->dev, NULL,
+ ip_local_deliver_finish);
+}
+
+static inline int ip_rcv_options(struct sk_buff *skb)
+{
+ struct ip_options *opt;
+ const struct iphdr *iph;
+ struct net_device *dev = skb->dev;
+
+ /* 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(dev_net(dev), IPSTATS_MIB_INDISCARDS);
+ goto drop;
+ }
+
+ iph = ip_hdr(skb);
+ opt = &(IPCB(skb)->opt);
+ opt->optlen = iph->ihl*4 - sizeof(struct iphdr);
+
+ if (ip_options_compile(dev_net(dev), opt, skb)) {
+ IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INHDRERRORS);
+ goto drop;
+ }
+
+ if (unlikely(opt->srr)) {
+ struct in_device *in_dev = __in_dev_get_rcu(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 %pI4 -> %pI4\n",
+ &iph->saddr, &iph->daddr);
+ goto drop;
+ }
+ }
+
+ if (ip_options_rcv_srr(skb))
+ goto drop;
+ }
+
+ return 0;
+drop:
+ return -1;
+}
+
+static int ip_rcv_finish(struct sk_buff *skb)
+{
+ const struct iphdr *iph = ip_hdr(skb);
+ struct rtable *rt;
+
+ /*
+ * Initialise the virtual path cache for the packet. It describes
+ * how the packet travels inside Linux networking.
+ */
+ if (skb_dst(skb) == NULL) {
+ int err = ip_route_input_noref(skb, iph->daddr, iph->saddr,
+ iph->tos, skb->dev);
+ if (unlikely(err)) {
+ if (err == -EHOSTUNREACH)
+ IP_INC_STATS_BH(dev_net(skb->dev),
+ IPSTATS_MIB_INADDRERRORS);
+ else if (err == -ENETUNREACH)
+ IP_INC_STATS_BH(dev_net(skb->dev),
+ IPSTATS_MIB_INNOROUTES);
+ else if (err == -EXDEV)
+ NET_INC_STATS_BH(dev_net(skb->dev),
+ LINUX_MIB_IPRPFILTER);
+ goto drop;
+ }
+ }
+
+#ifdef CONFIG_IP_ROUTE_CLASSID
+ if (unlikely(skb_dst(skb)->tclassid)) {
+ struct ip_rt_acct *st = this_cpu_ptr(ip_rt_acct);
+ u32 idx = skb_dst(skb)->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 && ip_rcv_options(skb))
+ goto drop;
+
+ rt = skb_rtable(skb);
+ if (rt->rt_type == RTN_MULTICAST) {
+ IP_UPD_PO_STATS_BH(dev_net(rt->dst.dev), IPSTATS_MIB_INMCAST,
+ skb->len);
+ } else if (rt->rt_type == RTN_BROADCAST)
+ IP_UPD_PO_STATS_BH(dev_net(rt->dst.dev), IPSTATS_MIB_INBCAST,
+ skb->len);
+
+ return dst_input(skb);
+
+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 net_device *orig_dev)
+{
+ const struct iphdr *iph;
+ u32 len;
+
+ /* 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_UPD_PO_STATS_BH(dev_net(dev), IPSTATS_MIB_IN, skb->len);
+
+ if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL) {
+ IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
+ goto out;
+ }
+
+ if (!pskb_may_pull(skb, sizeof(struct iphdr)))
+ goto inhdr_error;
+
+ iph = ip_hdr(skb);
+
+ /*
+ * RFC1122: 3.2.1.2 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 = ip_hdr(skb);
+
+ if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
+ goto inhdr_error;
+
+ len = ntohs(iph->tot_len);
+ if (skb->len < len) {
+ IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INTRUNCATEDPKTS);
+ goto drop;
+ } else if (len < (iph->ihl*4))
+ 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(dev_net(dev), IPSTATS_MIB_INDISCARDS);
+ goto drop;
+ }
+
+ /* Remove any debris in the socket control block */
+ memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
+
+ /* Must drop socket now because of tproxy. */
+ skb_orphan(skb);
+
+ return NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, skb, dev, NULL,
+ ip_rcv_finish);
+
+inhdr_error:
+ IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INHDRERRORS);
+drop:
+ kfree_skb(skb);
+out:
+ return NET_RX_DROP;
+}
generated by cgit v1.2.3 (git 2.25.1) at 2024-06-06 19:47:51 +0000