diff options
Diffstat (limited to 'net/ipv4/ip_input.c')
| -rw-r--r-- | net/ipv4/ip_input.c | 431 |
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 0000000..a0d0833 --- /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); |
