| /* |
| * 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. |
| */ |
| |
| #define pr_fmt(fmt) "IPv4: " fmt |
| |
| #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 <net/inet_ecn.h> |
| #include <linux/netfilter_ipv4.h> |
| #include <net/xfrm.h> |
| #include <linux/mroute.h> |
| #include <linux/netlink.h> |
| #include <net/dst_metadata.h> |
| |
| /* |
| * Process Router Attention IP option (RFC 2113) |
| */ |
| bool 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; |
| struct net *net = dev_net(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), net)) { |
| if (ip_is_fragment(ip_hdr(skb))) { |
| if (ip_defrag(net, skb, IP_DEFRAG_CALL_RA_CHAIN)) |
| return true; |
| } |
| 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 true; |
| } |
| return false; |
| } |
| |
| static int ip_local_deliver_finish(struct net *net, struct sock *sk, struct sk_buff *skb) |
| { |
| __skb_pull(skb, skb_network_header_len(skb)); |
| |
| rcu_read_lock(); |
| { |
| int protocol = ip_hdr(skb)->protocol; |
| const struct net_protocol *ipprot; |
| int raw; |
| |
| resubmit: |
| raw = raw_local_deliver(skb, protocol); |
| |
| ipprot = rcu_dereference(inet_protos[protocol]); |
| if (ipprot) { |
| int ret; |
| |
| 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(net, IPSTATS_MIB_INDELIVERS); |
| } else { |
| if (!raw) { |
| if (xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { |
| __IP_INC_STATS(net, IPSTATS_MIB_INUNKNOWNPROTOS); |
| icmp_send(skb, ICMP_DEST_UNREACH, |
| ICMP_PROT_UNREACH, 0); |
| } |
| kfree_skb(skb); |
| } else { |
| __IP_INC_STATS(net, IPSTATS_MIB_INDELIVERS); |
| consume_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. |
| */ |
| struct net *net = dev_net(skb->dev); |
| |
| if (ip_is_fragment(ip_hdr(skb))) { |
| if (ip_defrag(net, skb, IP_DEFRAG_LOCAL_DELIVER)) |
| return 0; |
| } |
| |
| return NF_HOOK(NFPROTO_IPV4, NF_INET_LOCAL_IN, |
| net, NULL, skb, skb->dev, NULL, |
| ip_local_deliver_finish); |
| } |
| |
| static inline bool 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(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(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_info_ratelimited("source route option %pI4 -> %pI4\n", |
| &iph->saddr, |
| &iph->daddr); |
| goto drop; |
| } |
| } |
| |
| if (ip_options_rcv_srr(skb)) |
| goto drop; |
| } |
| |
| return false; |
| drop: |
| return true; |
| } |
| |
| static int ip_rcv_finish(struct net *net, struct sock *sk, struct sk_buff *skb) |
| { |
| const struct iphdr *iph = ip_hdr(skb); |
| struct rtable *rt; |
| |
| if (net->ipv4.sysctl_ip_early_demux && |
| !skb_dst(skb) && |
| !skb->sk && |
| !ip_is_fragment(iph)) { |
| const struct net_protocol *ipprot; |
| int protocol = iph->protocol; |
| |
| ipprot = rcu_dereference(inet_protos[protocol]); |
| if (ipprot && ipprot->early_demux) { |
| ipprot->early_demux(skb); |
| /* must reload iph, skb->head might have changed */ |
| iph = ip_hdr(skb); |
| } |
| } |
| |
| /* |
| * Initialise the virtual path cache for the packet. It describes |
| * how the packet travels inside Linux networking. |
| */ |
| if (!skb_valid_dst(skb)) { |
| int err = ip_route_input_noref(skb, iph->daddr, iph->saddr, |
| iph->tos, skb->dev); |
| if (unlikely(err)) { |
| if (err == -EXDEV) |
| __NET_INC_STATS(net, 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(net, IPSTATS_MIB_INMCAST, skb->len); |
| } else if (rt->rt_type == RTN_BROADCAST) { |
| __IP_UPD_PO_STATS(net, IPSTATS_MIB_INBCAST, skb->len); |
| } else if (skb->pkt_type == PACKET_BROADCAST || |
| skb->pkt_type == PACKET_MULTICAST) { |
| struct in_device *in_dev = __in_dev_get_rcu(skb->dev); |
| |
| /* RFC 1122 3.3.6: |
| * |
| * When a host sends a datagram to a link-layer broadcast |
| * address, the IP destination address MUST be a legal IP |
| * broadcast or IP multicast address. |
| * |
| * A host SHOULD silently discard a datagram that is received |
| * via a link-layer broadcast (see Section 2.4) but does not |
| * specify an IP multicast or broadcast destination address. |
| * |
| * This doesn't explicitly say L2 *broadcast*, but broadcast is |
| * in a way a form of multicast and the most common use case for |
| * this is 802.11 protecting against cross-station spoofing (the |
| * so-called "hole-196" attack) so do it for both. |
| */ |
| if (in_dev && |
| IN_DEV_ORCONF(in_dev, DROP_UNICAST_IN_L2_MULTICAST)) |
| goto drop; |
| } |
| |
| 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; |
| struct net *net; |
| 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; |
| |
| |
| net = dev_net(dev); |
| __IP_UPD_PO_STATS(net, IPSTATS_MIB_IN, skb->len); |
| |
| skb = skb_share_check(skb, GFP_ATOMIC); |
| if (!skb) { |
| __IP_INC_STATS(net, 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; |
| |
| BUILD_BUG_ON(IPSTATS_MIB_ECT1PKTS != IPSTATS_MIB_NOECTPKTS + INET_ECN_ECT_1); |
| BUILD_BUG_ON(IPSTATS_MIB_ECT0PKTS != IPSTATS_MIB_NOECTPKTS + INET_ECN_ECT_0); |
| BUILD_BUG_ON(IPSTATS_MIB_CEPKTS != IPSTATS_MIB_NOECTPKTS + INET_ECN_CE); |
| __IP_ADD_STATS(net, |
| IPSTATS_MIB_NOECTPKTS + (iph->tos & INET_ECN_MASK), |
| max_t(unsigned short, 1, skb_shinfo(skb)->gso_segs)); |
| |
| 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 csum_error; |
| |
| len = ntohs(iph->tot_len); |
| if (skb->len < len) { |
| __IP_INC_STATS(net, 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(net, IPSTATS_MIB_INDISCARDS); |
| goto drop; |
| } |
| |
| skb->transport_header = skb->network_header + iph->ihl*4; |
| |
| /* 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, |
| net, NULL, skb, dev, NULL, |
| ip_rcv_finish); |
| |
| csum_error: |
| __IP_INC_STATS(net, IPSTATS_MIB_CSUMERRORS); |
| inhdr_error: |
| __IP_INC_STATS(net, IPSTATS_MIB_INHDRERRORS); |
| drop: |
| kfree_skb(skb); |
| out: |
| return NET_RX_DROP; |
| } |