/* * NET3: Implementation of the ICMP protocol layer. * * Alan Cox, <alan@redhat.com> * * Version: $Id: icmp.c,v 1.85 2002/02/01 22:01:03 davem Exp $ * * 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. * * Some of the function names and the icmp unreach table for this * module were derived from [icmp.c 1.0.11 06/02/93] by * Ross Biro, Fred N. van Kempen, Mark Evans, Alan Cox, Gerhard Koerting. * Other than that this module is a complete rewrite. * * Fixes: * Clemens Fruhwirth : introduce global icmp rate limiting * with icmp type masking ability instead * of broken per type icmp timeouts. * Mike Shaver : RFC1122 checks. * Alan Cox : Multicast ping reply as self. * Alan Cox : Fix atomicity lockup in ip_build_xmit * call. * Alan Cox : Added 216,128 byte paths to the MTU * code. * Martin Mares : RFC1812 checks. * Martin Mares : Can be configured to follow redirects * if acting as a router _without_ a * routing protocol (RFC 1812). * Martin Mares : Echo requests may be configured to * be ignored (RFC 1812). * Martin Mares : Limitation of ICMP error message * transmit rate (RFC 1812). * Martin Mares : TOS and Precedence set correctly * (RFC 1812). * Martin Mares : Now copying as much data from the * original packet as we can without * exceeding 576 bytes (RFC 1812). * Willy Konynenberg : Transparent proxying support. * Keith Owens : RFC1191 correction for 4.2BSD based * path MTU bug. * Thomas Quinot : ICMP Dest Unreach codes up to 15 are * valid (RFC 1812). * Andi Kleen : Check all packet lengths properly * and moved all kfree_skb() up to * icmp_rcv. * Andi Kleen : Move the rate limit bookkeeping * into the dest entry and use a token * bucket filter (thanks to ANK). Make * the rates sysctl configurable. * Yu Tianli : Fixed two ugly bugs in icmp_send * - IP option length was accounted wrongly * - ICMP header length was not accounted * at all. * Tristan Greaves : Added sysctl option to ignore bogus * broadcast responses from broken routers. * * To Fix: * * - Should use skb_pull() instead of all the manual checking. * This would also greatly simply some upper layer error handlers. --AK * */ #include <linux/module.h> #include <linux/types.h> #include <linux/jiffies.h> #include <linux/kernel.h> #include <linux/fcntl.h> #include <linux/socket.h> #include <linux/in.h> #include <linux/inet.h> #include <linux/inetdevice.h> #include <linux/netdevice.h> #include <linux/string.h> #include <linux/netfilter_ipv4.h> #include <net/snmp.h> #include <net/ip.h> #include <net/route.h> #include <net/protocol.h> #include <net/icmp.h> #include <net/tcp.h> #include <net/udp.h> #include <net/raw.h> #include <linux/skbuff.h> #include <net/sock.h> #include <linux/errno.h> #include <linux/timer.h> #include <linux/init.h> #include <asm/system.h> #include <asm/uaccess.h> #include <net/checksum.h> #include <net/xfrm.h> /* * Build xmit assembly blocks */ struct icmp_bxm { struct sk_buff *skb; int offset; int data_len; struct { struct icmphdr icmph; __be32 times[3]; } data; int head_len; struct ip_options replyopts; unsigned char optbuf[40]; }; /* * Statistics */ DEFINE_SNMP_STAT(struct icmp_mib, icmp_statistics) __read_mostly; DEFINE_SNMP_STAT(struct icmpmsg_mib, icmpmsg_statistics) __read_mostly; /* An array of errno for error messages from dest unreach. */ /* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */ struct icmp_err icmp_err_convert[] = { { .errno = ENETUNREACH, /* ICMP_NET_UNREACH */ .fatal = 0, }, { .errno = EHOSTUNREACH, /* ICMP_HOST_UNREACH */ .fatal = 0, }, { .errno = ENOPROTOOPT /* ICMP_PROT_UNREACH */, .fatal = 1, }, { .errno = ECONNREFUSED, /* ICMP_PORT_UNREACH */ .fatal = 1, }, { .errno = EMSGSIZE, /* ICMP_FRAG_NEEDED */ .fatal = 0, }, { .errno = EOPNOTSUPP, /* ICMP_SR_FAILED */ .fatal = 0, }, { .errno = ENETUNREACH, /* ICMP_NET_UNKNOWN */ .fatal = 1, }, { .errno = EHOSTDOWN, /* ICMP_HOST_UNKNOWN */ .fatal = 1, }, { .errno = ENONET, /* ICMP_HOST_ISOLATED */ .fatal = 1, }, { .errno = ENETUNREACH, /* ICMP_NET_ANO */ .fatal = 1, }, { .errno = EHOSTUNREACH, /* ICMP_HOST_ANO */ .fatal = 1, }, { .errno = ENETUNREACH, /* ICMP_NET_UNR_TOS */ .fatal = 0, }, { .errno = EHOSTUNREACH, /* ICMP_HOST_UNR_TOS */ .fatal = 0, }, { .errno = EHOSTUNREACH, /* ICMP_PKT_FILTERED */ .fatal = 1, }, { .errno = EHOSTUNREACH, /* ICMP_PREC_VIOLATION */ .fatal = 1, }, { .errno = EHOSTUNREACH, /* ICMP_PREC_CUTOFF */ .fatal = 1, }, }; /* Control parameters for ECHO replies. */ int sysctl_icmp_echo_ignore_all __read_mostly; int sysctl_icmp_echo_ignore_broadcasts __read_mostly = 1; /* Control parameter - ignore bogus broadcast responses? */ int sysctl_icmp_ignore_bogus_error_responses __read_mostly = 1; /* * Configurable global rate limit. * * ratelimit defines tokens/packet consumed for dst->rate_token bucket * ratemask defines which icmp types are ratelimited by setting * it's bit position. * * default: * dest unreachable (3), source quench (4), * time exceeded (11), parameter problem (12) */ int sysctl_icmp_ratelimit __read_mostly = 1 * HZ; int sysctl_icmp_ratemask __read_mostly = 0x1818; int sysctl_icmp_errors_use_inbound_ifaddr __read_mostly; /* * ICMP control array. This specifies what to do with each ICMP. */ struct icmp_control { void (*handler)(struct sk_buff *skb); short error; /* This ICMP is classed as an error message */ }; static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1]; /* * The ICMP socket(s). This is the most convenient way to flow control * our ICMP output as well as maintain a clean interface throughout * all layers. All Socketless IP sends will soon be gone. * * On SMP we have one ICMP socket per-cpu. */ static DEFINE_PER_CPU(struct socket *, __icmp_socket) = NULL; #define icmp_socket __get_cpu_var(__icmp_socket) static inline int icmp_xmit_lock(void) { local_bh_disable(); if (unlikely(!spin_trylock(&icmp_socket->sk->sk_lock.slock))) { /* This can happen if the output path signals a * dst_link_failure() for an outgoing ICMP packet. */ local_bh_enable(); return 1; } return 0; } static inline void icmp_xmit_unlock(void) { spin_unlock_bh(&icmp_socket->sk->sk_lock.slock); } /* * Send an ICMP frame. */ /* * Check transmit rate limitation for given message. * The rate information is held in the destination cache now. * This function is generic and could be used for other purposes * too. It uses a Token bucket filter as suggested by Alexey Kuznetsov. * * Note that the same dst_entry fields are modified by functions in * route.c too, but these work for packet destinations while xrlim_allow * works for icmp destinations. This means the rate limiting information * for one "ip object" is shared - and these ICMPs are twice limited: * by source and by destination. * * RFC 1812: 4.3.2.8 SHOULD be able to limit error message rate * SHOULD allow setting of rate limits * * Shared between ICMPv4 and ICMPv6. */ #define XRLIM_BURST_FACTOR 6 int xrlim_allow(struct dst_entry *dst, int timeout) { unsigned long now, token = dst->rate_tokens; int rc = 0; now = jiffies; token += now - dst->rate_last; dst->rate_last = now; if (token > XRLIM_BURST_FACTOR * timeout) token = XRLIM_BURST_FACTOR * timeout; if (token >= timeout) { token -= timeout; rc = 1; } dst->rate_tokens = token; return rc; } static inline int icmpv4_xrlim_allow(struct rtable *rt, int type, int code) { struct dst_entry *dst = &rt->u.dst; int rc = 1; if (type > NR_ICMP_TYPES) goto out; /* Don't limit PMTU discovery. */ if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) goto out; /* No rate limit on loopback */ if (dst->dev && (dst->dev->flags&IFF_LOOPBACK)) goto out; /* Limit if icmp type is enabled in ratemask. */ if ((1 << type) & sysctl_icmp_ratemask) rc = xrlim_allow(dst, sysctl_icmp_ratelimit); out: return rc; } /* * Maintain the counters used in the SNMP statistics for outgoing ICMP */ void icmp_out_count(unsigned char type) { ICMPMSGOUT_INC_STATS(type); ICMP_INC_STATS(ICMP_MIB_OUTMSGS); } /* * Checksum each fragment, and on the first include the headers and final * checksum. */ static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb) { struct icmp_bxm *icmp_param = (struct icmp_bxm *)from; __wsum csum; csum = skb_copy_and_csum_bits(icmp_param->skb, icmp_param->offset + offset, to, len, 0); skb->csum = csum_block_add(skb->csum, csum, odd); if (icmp_pointers[icmp_param->data.icmph.type].error) nf_ct_attach(skb, icmp_param->skb); return 0; } static void icmp_push_reply(struct icmp_bxm *icmp_param, struct ipcm_cookie *ipc, struct rtable *rt) { struct sk_buff *skb; if (ip_append_data(icmp_socket->sk, icmp_glue_bits, icmp_param, icmp_param->data_len+icmp_param->head_len, icmp_param->head_len, ipc, rt, MSG_DONTWAIT) < 0) ip_flush_pending_frames(icmp_socket->sk); else if ((skb = skb_peek(&icmp_socket->sk->sk_write_queue)) != NULL) { struct icmphdr *icmph = icmp_hdr(skb); __wsum csum = 0; struct sk_buff *skb1; skb_queue_walk(&icmp_socket->sk->sk_write_queue, skb1) { csum = csum_add(csum, skb1->csum); } csum = csum_partial_copy_nocheck((void *)&icmp_param->data, (char *)icmph, icmp_param->head_len, csum); icmph->checksum = csum_fold(csum); skb->ip_summed = CHECKSUM_NONE; ip_push_pending_frames(icmp_socket->sk); } } /* * Driving logic for building and sending ICMP messages. */ static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb) { struct sock *sk = icmp_socket->sk; struct inet_sock *inet = inet_sk(sk); struct ipcm_cookie ipc; struct rtable *rt = (struct rtable *)skb->dst; __be32 daddr; if (ip_options_echo(&icmp_param->replyopts, skb)) return; if (icmp_xmit_lock()) return; icmp_param->data.icmph.checksum = 0; inet->tos = ip_hdr(skb)->tos; daddr = ipc.addr = rt->rt_src; ipc.opt = NULL; if (icmp_param->replyopts.optlen) { ipc.opt = &icmp_param->replyopts; if (ipc.opt->srr) daddr = icmp_param->replyopts.faddr; } { struct flowi fl = { .nl_u = { .ip4_u = { .daddr = daddr, .saddr = rt->rt_spec_dst, .tos = RT_TOS(ip_hdr(skb)->tos) } }, .proto = IPPROTO_ICMP }; security_skb_classify_flow(skb, &fl); if (ip_route_output_key(rt->u.dst.dev->nd_net, &rt, &fl)) goto out_unlock; } if (icmpv4_xrlim_allow(rt, icmp_param->data.icmph.type, icmp_param->data.icmph.code)) icmp_push_reply(icmp_param, &ipc, rt); ip_rt_put(rt); out_unlock: icmp_xmit_unlock(); } /* * Send an ICMP message in response to a situation * * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. * MAY send more (we do). * MUST NOT change this header information. * MUST NOT reply to a multicast/broadcast IP address. * MUST NOT reply to a multicast/broadcast MAC address. * MUST reply to only the first fragment. */ void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info) { struct iphdr *iph; int room; struct icmp_bxm icmp_param; struct rtable *rt = (struct rtable *)skb_in->dst; struct ipcm_cookie ipc; __be32 saddr; u8 tos; struct net *net; if (!rt) goto out; net = rt->u.dst.dev->nd_net; /* * Find the original header. It is expected to be valid, of course. * Check this, icmp_send is called from the most obscure devices * sometimes. */ iph = ip_hdr(skb_in); if ((u8 *)iph < skb_in->head || (skb_in->network_header + sizeof(*iph)) > skb_in->tail) goto out; /* * No replies to physical multicast/broadcast */ if (skb_in->pkt_type != PACKET_HOST) goto out; /* * Now check at the protocol level */ if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) goto out; /* * Only reply to fragment 0. We byte re-order the constant * mask for efficiency. */ if (iph->frag_off & htons(IP_OFFSET)) goto out; /* * If we send an ICMP error to an ICMP error a mess would result.. */ if (icmp_pointers[type].error) { /* * We are an error, check if we are replying to an * ICMP error */ if (iph->protocol == IPPROTO_ICMP) { u8 _inner_type, *itp; itp = skb_header_pointer(skb_in, skb_network_header(skb_in) + (iph->ihl << 2) + offsetof(struct icmphdr, type) - skb_in->data, sizeof(_inner_type), &_inner_type); if (itp == NULL) goto out; /* * Assume any unknown ICMP type is an error. This * isn't specified by the RFC, but think about it.. */ if (*itp > NR_ICMP_TYPES || icmp_pointers[*itp].error) goto out; } } if (icmp_xmit_lock()) return; /* * Construct source address and options. */ saddr = iph->daddr; if (!(rt->rt_flags & RTCF_LOCAL)) { struct net_device *dev = NULL; if (rt->fl.iif && sysctl_icmp_errors_use_inbound_ifaddr) dev = dev_get_by_index(net, rt->fl.iif); if (dev) { saddr = inet_select_addr(dev, 0, RT_SCOPE_LINK); dev_put(dev); } else saddr = 0; } tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) | IPTOS_PREC_INTERNETCONTROL) : iph->tos; if (ip_options_echo(&icmp_param.replyopts, skb_in)) goto out_unlock; /* * Prepare data for ICMP header. */ icmp_param.data.icmph.type = type; icmp_param.data.icmph.code = code; icmp_param.data.icmph.un.gateway = info; icmp_param.data.icmph.checksum = 0; icmp_param.skb = skb_in; icmp_param.offset = skb_network_offset(skb_in); inet_sk(icmp_socket->sk)->tos = tos; ipc.addr = iph->saddr; ipc.opt = &icmp_param.replyopts; { struct flowi fl = { .nl_u = { .ip4_u = { .daddr = icmp_param.replyopts.srr ? icmp_param.replyopts.faddr : iph->saddr, .saddr = saddr, .tos = RT_TOS(tos) } }, .proto = IPPROTO_ICMP, .uli_u = { .icmpt = { .type = type, .code = code } } }; int err; struct rtable *rt2; security_skb_classify_flow(skb_in, &fl); if (__ip_route_output_key(net, &rt, &fl)) goto out_unlock; /* No need to clone since we're just using its address. */ rt2 = rt; err = xfrm_lookup((struct dst_entry **)&rt, &fl, NULL, 0); switch (err) { case 0: if (rt != rt2) goto route_done; break; case -EPERM: rt = NULL; break; default: goto out_unlock; } if (xfrm_decode_session_reverse(skb_in, &fl, AF_INET)) goto out_unlock; if (inet_addr_type(net, fl.fl4_src) == RTN_LOCAL) err = __ip_route_output_key(net, &rt2, &fl); else { struct flowi fl2 = {}; struct dst_entry *odst; fl2.fl4_dst = fl.fl4_src; if (ip_route_output_key(net, &rt2, &fl2)) goto out_unlock; /* Ugh! */ odst = skb_in->dst; err = ip_route_input(skb_in, fl.fl4_dst, fl.fl4_src, RT_TOS(tos), rt2->u.dst.dev); dst_release(&rt2->u.dst); rt2 = (struct rtable *)skb_in->dst; skb_in->dst = odst; } if (err) goto out_unlock; err = xfrm_lookup((struct dst_entry **)&rt2, &fl, NULL, XFRM_LOOKUP_ICMP); if (err == -ENOENT) { if (!rt) goto out_unlock; goto route_done; } dst_release(&rt->u.dst); rt = rt2; if (err) goto out_unlock; } route_done: if (!icmpv4_xrlim_allow(rt, type, code)) goto ende; /* RFC says return as much as we can without exceeding 576 bytes. */ room = dst_mtu(&rt->u.dst); if (room > 576) room = 576; room -= sizeof(struct iphdr) + icmp_param.replyopts.optlen; room -= sizeof(struct icmphdr); icmp_param.data_len = skb_in->len - icmp_param.offset; if (icmp_param.data_len > room) icmp_param.data_len = room; icmp_param.head_len = sizeof(struct icmphdr); icmp_push_reply(&icmp_param, &ipc, rt); ende: ip_rt_put(rt); out_unlock: icmp_xmit_unlock(); out:; } /* * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEED, and ICMP_QUENCH. */ static void icmp_unreach(struct sk_buff *skb) { struct iphdr *iph; struct icmphdr *icmph; int hash, protocol; struct net_protocol *ipprot; u32 info = 0; struct net *net; net = skb->dst->dev->nd_net; /* * Incomplete header ? * Only checks for the IP header, there should be an * additional check for longer headers in upper levels. */ if (!pskb_may_pull(skb, sizeof(struct iphdr))) goto out_err; icmph = icmp_hdr(skb); iph = (struct iphdr *)skb->data; if (iph->ihl < 5) /* Mangled header, drop. */ goto out_err; if (icmph->type == ICMP_DEST_UNREACH) { switch (icmph->code & 15) { case ICMP_NET_UNREACH: case ICMP_HOST_UNREACH: case ICMP_PROT_UNREACH: case ICMP_PORT_UNREACH: break; case ICMP_FRAG_NEEDED: if (ipv4_config.no_pmtu_disc) { LIMIT_NETDEBUG(KERN_INFO "ICMP: %u.%u.%u.%u: " "fragmentation needed " "and DF set.\n", NIPQUAD(iph->daddr)); } else { info = ip_rt_frag_needed(net, iph, ntohs(icmph->un.frag.mtu)); if (!info) goto out; } break; case ICMP_SR_FAILED: LIMIT_NETDEBUG(KERN_INFO "ICMP: %u.%u.%u.%u: Source " "Route Failed.\n", NIPQUAD(iph->daddr)); break; default: break; } if (icmph->code > NR_ICMP_UNREACH) goto out; } else if (icmph->type == ICMP_PARAMETERPROB) info = ntohl(icmph->un.gateway) >> 24; /* * Throw it at our lower layers * * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed * header. * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the * transport layer. * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to * transport layer. */ /* * Check the other end isnt violating RFC 1122. Some routers send * bogus responses to broadcast frames. If you see this message * first check your netmask matches at both ends, if it does then * get the other vendor to fix their kit. */ if (!sysctl_icmp_ignore_bogus_error_responses && inet_addr_type(net, iph->daddr) == RTN_BROADCAST) { if (net_ratelimit()) printk(KERN_WARNING "%u.%u.%u.%u sent an invalid ICMP " "type %u, code %u " "error to a broadcast: %u.%u.%u.%u on %s\n", NIPQUAD(ip_hdr(skb)->saddr), icmph->type, icmph->code, NIPQUAD(iph->daddr), skb->dev->name); goto out; } /* Checkin full IP header plus 8 bytes of protocol to * avoid additional coding at protocol handlers. */ if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) goto out; iph = (struct iphdr *)skb->data; protocol = iph->protocol; /* * Deliver ICMP message to raw sockets. Pretty useless feature? */ raw_icmp_error(skb, protocol, info); hash = protocol & (MAX_INET_PROTOS - 1); rcu_read_lock(); ipprot = rcu_dereference(inet_protos[hash]); if (ipprot && ipprot->err_handler) ipprot->err_handler(skb, info); rcu_read_unlock(); out: return; out_err: ICMP_INC_STATS_BH(ICMP_MIB_INERRORS); goto out; } /* * Handle ICMP_REDIRECT. */ static void icmp_redirect(struct sk_buff *skb) { struct iphdr *iph; if (skb->len < sizeof(struct iphdr)) goto out_err; /* * Get the copied header of the packet that caused the redirect */ if (!pskb_may_pull(skb, sizeof(struct iphdr))) goto out; iph = (struct iphdr *)skb->data; switch (icmp_hdr(skb)->code & 7) { case ICMP_REDIR_NET: case ICMP_REDIR_NETTOS: /* * As per RFC recommendations now handle it as a host redirect. */ case ICMP_REDIR_HOST: case ICMP_REDIR_HOSTTOS: ip_rt_redirect(ip_hdr(skb)->saddr, iph->daddr, icmp_hdr(skb)->un.gateway, iph->saddr, skb->dev); break; } out: return; out_err: ICMP_INC_STATS_BH(ICMP_MIB_INERRORS); goto out; } /* * Handle ICMP_ECHO ("ping") requests. * * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo * requests. * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be * included in the reply. * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring * echo requests, MUST have default=NOT. * See also WRT handling of options once they are done and working. */ static void icmp_echo(struct sk_buff *skb) { if (!sysctl_icmp_echo_ignore_all) { struct icmp_bxm icmp_param; icmp_param.data.icmph = *icmp_hdr(skb); icmp_param.data.icmph.type = ICMP_ECHOREPLY; icmp_param.skb = skb; icmp_param.offset = 0; icmp_param.data_len = skb->len; icmp_param.head_len = sizeof(struct icmphdr); icmp_reply(&icmp_param, skb); } } /* * Handle ICMP Timestamp requests. * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests. * SHOULD be in the kernel for minimum random latency. * MUST be accurate to a few minutes. * MUST be updated at least at 15Hz. */ static void icmp_timestamp(struct sk_buff *skb) { struct timeval tv; struct icmp_bxm icmp_param; /* * Too short. */ if (skb->len < 4) goto out_err; /* * Fill in the current time as ms since midnight UT: */ do_gettimeofday(&tv); icmp_param.data.times[1] = htonl((tv.tv_sec % 86400) * 1000 + tv.tv_usec / 1000); icmp_param.data.times[2] = icmp_param.data.times[1]; if (skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4)) BUG(); icmp_param.data.icmph = *icmp_hdr(skb); icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY; icmp_param.data.icmph.code = 0; icmp_param.skb = skb; icmp_param.offset = 0; icmp_param.data_len = 0; icmp_param.head_len = sizeof(struct icmphdr) + 12; icmp_reply(&icmp_param, skb); out: return; out_err: ICMP_INC_STATS_BH(ICMP_MIB_INERRORS); goto out; } /* * Handle ICMP_ADDRESS_MASK requests. (RFC950) * * RFC1122 (3.2.2.9). A host MUST only send replies to * ADDRESS_MASK requests if it's been configured as an address mask * agent. Receiving a request doesn't constitute implicit permission to * act as one. Of course, implementing this correctly requires (SHOULD) * a way to turn the functionality on and off. Another one for sysctl(), * I guess. -- MS * * RFC1812 (4.3.3.9). A router MUST implement it. * A router SHOULD have switch turning it on/off. * This switch MUST be ON by default. * * Gratuitous replies, zero-source replies are not implemented, * that complies with RFC. DO NOT implement them!!! All the idea * of broadcast addrmask replies as specified in RFC950 is broken. * The problem is that it is not uncommon to have several prefixes * on one physical interface. Moreover, addrmask agent can even be * not aware of existing another prefixes. * If source is zero, addrmask agent cannot choose correct prefix. * Gratuitous mask announcements suffer from the same problem. * RFC1812 explains it, but still allows to use ADDRMASK, * that is pretty silly. --ANK * * All these rules are so bizarre, that I removed kernel addrmask * support at all. It is wrong, it is obsolete, nobody uses it in * any case. --ANK * * Furthermore you can do it with a usermode address agent program * anyway... */ static void icmp_address(struct sk_buff *skb) { #if 0 if (net_ratelimit()) printk(KERN_DEBUG "a guy asks for address mask. Who is it?\n"); #endif } /* * RFC1812 (4.3.3.9). A router SHOULD listen all replies, and complain * loudly if an inconsistency is found. */ static void icmp_address_reply(struct sk_buff *skb) { struct rtable *rt = (struct rtable *)skb->dst; struct net_device *dev = skb->dev; struct in_device *in_dev; struct in_ifaddr *ifa; if (skb->len < 4 || !(rt->rt_flags&RTCF_DIRECTSRC)) goto out; in_dev = in_dev_get(dev); if (!in_dev) goto out; rcu_read_lock(); if (in_dev->ifa_list && IN_DEV_LOG_MARTIANS(in_dev) && IN_DEV_FORWARD(in_dev)) { __be32 _mask, *mp; mp = skb_header_pointer(skb, 0, sizeof(_mask), &_mask); BUG_ON(mp == NULL); for (ifa = in_dev->ifa_list; ifa; ifa = ifa->ifa_next) { if (*mp == ifa->ifa_mask && inet_ifa_match(rt->rt_src, ifa)) break; } if (!ifa && net_ratelimit()) { printk(KERN_INFO "Wrong address mask %u.%u.%u.%u from " "%s/%u.%u.%u.%u\n", NIPQUAD(*mp), dev->name, NIPQUAD(rt->rt_src)); } } rcu_read_unlock(); in_dev_put(in_dev); out:; } static void icmp_discard(struct sk_buff *skb) { } /* * Deal with incoming ICMP packets. */ int icmp_rcv(struct sk_buff *skb) { struct icmphdr *icmph; struct rtable *rt = (struct rtable *)skb->dst; if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { int nh; if (!(skb->sp && skb->sp->xvec[skb->sp->len - 1]->props.flags & XFRM_STATE_ICMP)) goto drop; if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr))) goto drop; nh = skb_network_offset(skb); skb_set_network_header(skb, sizeof(*icmph)); if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb)) goto drop; skb_set_network_header(skb, nh); } ICMP_INC_STATS_BH(ICMP_MIB_INMSGS); switch (skb->ip_summed) { case CHECKSUM_COMPLETE: if (!csum_fold(skb->csum)) break; /* fall through */ case CHECKSUM_NONE: skb->csum = 0; if (__skb_checksum_complete(skb)) goto error; } __skb_pull(skb, sizeof(*icmph)); icmph = icmp_hdr(skb); ICMPMSGIN_INC_STATS_BH(icmph->type); /* * 18 is the highest 'known' ICMP type. Anything else is a mystery * * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently * discarded. */ if (icmph->type > NR_ICMP_TYPES) goto error; /* * Parse the ICMP message */ if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) { /* * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be * silently ignored (we let user decide with a sysctl). * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently * discarded if to broadcast/multicast. */ if ((icmph->type == ICMP_ECHO || icmph->type == ICMP_TIMESTAMP) && sysctl_icmp_echo_ignore_broadcasts) { goto error; } if (icmph->type != ICMP_ECHO && icmph->type != ICMP_TIMESTAMP && icmph->type != ICMP_ADDRESS && icmph->type != ICMP_ADDRESSREPLY) { goto error; } } icmp_pointers[icmph->type].handler(skb); drop: kfree_skb(skb); return 0; error: ICMP_INC_STATS_BH(ICMP_MIB_INERRORS); goto drop; } /* * This table is the definition of how we handle ICMP. */ static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = { [ICMP_ECHOREPLY] = { .handler = icmp_discard, }, [1] = { .handler = icmp_discard, .error = 1, }, [2] = { .handler = icmp_discard, .error = 1, }, [ICMP_DEST_UNREACH] = { .handler = icmp_unreach, .error = 1, }, [ICMP_SOURCE_QUENCH] = { .handler = icmp_unreach, .error = 1, }, [ICMP_REDIRECT] = { .handler = icmp_redirect, .error = 1, }, [6] = { .handler = icmp_discard, .error = 1, }, [7] = { .handler = icmp_discard, .error = 1, }, [ICMP_ECHO] = { .handler = icmp_echo, }, [9] = { .handler = icmp_discard, .error = 1, }, [10] = { .handler = icmp_discard, .error = 1, }, [ICMP_TIME_EXCEEDED] = { .handler = icmp_unreach, .error = 1, }, [ICMP_PARAMETERPROB] = { .handler = icmp_unreach, .error = 1, }, [ICMP_TIMESTAMP] = { .handler = icmp_timestamp, }, [ICMP_TIMESTAMPREPLY] = { .handler = icmp_discard, }, [ICMP_INFO_REQUEST] = { .handler = icmp_discard, }, [ICMP_INFO_REPLY] = { .handler = icmp_discard, }, [ICMP_ADDRESS] = { .handler = icmp_address, }, [ICMP_ADDRESSREPLY] = { .handler = icmp_address_reply, }, }; void __init icmp_init(struct net_proto_family *ops) { struct inet_sock *inet; int i; for_each_possible_cpu(i) { int err; err = sock_create_kern(PF_INET, SOCK_RAW, IPPROTO_ICMP, &per_cpu(__icmp_socket, i)); if (err < 0) panic("Failed to create the ICMP control socket.\n"); per_cpu(__icmp_socket, i)->sk->sk_allocation = GFP_ATOMIC; /* Enough space for 2 64K ICMP packets, including * sk_buff struct overhead. */ per_cpu(__icmp_socket, i)->sk->sk_sndbuf = (2 * ((64 * 1024) + sizeof(struct sk_buff))); inet = inet_sk(per_cpu(__icmp_socket, i)->sk); inet->uc_ttl = -1; inet->pmtudisc = IP_PMTUDISC_DONT; /* Unhash it so that IP input processing does not even * see it, we do not wish this socket to see incoming * packets. */ per_cpu(__icmp_socket, i)->sk->sk_prot->unhash(per_cpu(__icmp_socket, i)->sk); } } EXPORT_SYMBOL(icmp_err_convert); EXPORT_SYMBOL(icmp_send); EXPORT_SYMBOL(icmp_statistics); EXPORT_SYMBOL(xrlim_allow);