/* * NET3: Implementation of the ICMP protocol layer. * * Alan Cox, * * Version: $Id: icmp.c,v 1.82.2.1 2001/12/13 08:59:27 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 #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * Build xmit assembly blocks */ struct icmp_bxm { struct sk_buff *skb; int offset; int data_len; unsigned int csum; struct { struct icmphdr icmph; __u32 times[3]; } data; int head_len; struct ip_options replyopts; unsigned char optbuf[40]; }; /* * Statistics */ struct icmp_mib icmp_statistics[NR_CPUS*2]; /* An array of errno for error messages from dest unreach. */ /* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOS_UNREACH and SR_FAIELD MUST be considered 'transient errs'. */ struct icmp_err icmp_err_convert[] = { { ENETUNREACH, 0 }, /* ICMP_NET_UNREACH */ { EHOSTUNREACH, 0 }, /* ICMP_HOST_UNREACH */ { ENOPROTOOPT, 1 }, /* ICMP_PROT_UNREACH */ { ECONNREFUSED, 1 }, /* ICMP_PORT_UNREACH */ { EMSGSIZE, 0 }, /* ICMP_FRAG_NEEDED */ { EOPNOTSUPP, 0 }, /* ICMP_SR_FAILED */ { ENETUNREACH, 1 }, /* ICMP_NET_UNKNOWN */ { EHOSTDOWN, 1 }, /* ICMP_HOST_UNKNOWN */ { ENONET, 1 }, /* ICMP_HOST_ISOLATED */ { ENETUNREACH, 1 }, /* ICMP_NET_ANO */ { EHOSTUNREACH, 1 }, /* ICMP_HOST_ANO */ { ENETUNREACH, 0 }, /* ICMP_NET_UNR_TOS */ { EHOSTUNREACH, 0 }, /* ICMP_HOST_UNR_TOS */ { EHOSTUNREACH, 1 }, /* ICMP_PKT_FILTERED */ { EHOSTUNREACH, 1 }, /* ICMP_PREC_VIOLATION */ { EHOSTUNREACH, 1 } /* ICMP_PREC_CUTOFF */ }; /* Control parameters for ECHO replies. */ int sysctl_icmp_echo_ignore_all; int sysctl_icmp_echo_ignore_broadcasts; /* Control parameter - ignore bogus broadcast responses? */ int sysctl_icmp_ignore_bogus_error_responses; /* * 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 = 1*HZ; int sysctl_icmp_ratemask = 0x1818; /* * ICMP control array. This specifies what to do with each ICMP. */ struct icmp_control { unsigned long *output; /* Address to increment on output */ unsigned long *input; /* Address to increment on input */ void (*handler)(struct sk_buff *skb); short error; /* This ICMP is classed as an error message */ }; static struct icmp_control icmp_pointers[NR_ICMP_TYPES+1]; /* * The ICMP socket. 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. */ struct inode icmp_inode; struct socket *icmp_socket = &icmp_inode.u.socket_i; /* ICMPv4 socket is only a bit non-reenterable (unlike ICMPv6, which is strongly non-reenterable). A bit later it will be made reenterable and the lock may be removed then. */ static int icmp_xmit_holder = -1; static int icmp_xmit_lock_bh(void) { if (!spin_trylock(&icmp_socket->sk->lock.slock)) { if (icmp_xmit_holder == smp_processor_id()) return -EAGAIN; spin_lock(&icmp_socket->sk->lock.slock); } icmp_xmit_holder = smp_processor_id(); return 0; } static __inline__ int icmp_xmit_lock(void) { int ret; local_bh_disable(); ret = icmp_xmit_lock_bh(); if (ret) local_bh_enable(); return ret; } static void icmp_xmit_unlock_bh(void) { icmp_xmit_holder = -1; spin_unlock(&icmp_socket->sk->lock.slock); } static __inline__ void icmp_xmit_unlock(void) { icmp_xmit_unlock_bh(); local_bh_enable(); } /* * 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; now = jiffies; dst->rate_tokens += now - dst->rate_last; dst->rate_last = now; if (dst->rate_tokens > XRLIM_BURST_FACTOR*timeout) dst->rate_tokens = XRLIM_BURST_FACTOR*timeout; if (dst->rate_tokens >= timeout) { dst->rate_tokens -= timeout; return 1; } return 0; } static inline int icmpv4_xrlim_allow(struct rtable *rt, int type, int code) { struct dst_entry *dst = &rt->u.dst; if (type > NR_ICMP_TYPES) return 1; /* Don't limit PMTU discovery. */ if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) return 1; /* No rate limit on loopback */ if (dst->dev && (dst->dev->flags&IFF_LOOPBACK)) return 1; /* Limit if icmp type is enabled in ratemask. */ if((1 << type) & sysctl_icmp_ratemask) return xrlim_allow(dst, sysctl_icmp_ratelimit); else return 1; } /* * Maintain the counters used in the SNMP statistics for outgoing ICMP */ static void icmp_out_count(int type) { if (type>NR_ICMP_TYPES) return; (icmp_pointers[type].output)[(smp_processor_id()*2+!in_softirq())*sizeof(struct icmp_mib)/sizeof(unsigned long)]++; ICMP_INC_STATS(IcmpOutMsgs); } /* * Checksum each fragment, and on the first include the headers and final checksum. */ static int icmp_glue_bits(const void *p, char *to, unsigned int offset, unsigned int fraglen) { struct icmp_bxm *icmp_param = (struct icmp_bxm *)p; struct icmphdr *icmph; unsigned int csum; if (offset) { icmp_param->csum=skb_copy_and_csum_bits(icmp_param->skb, icmp_param->offset+(offset-icmp_param->head_len), to, fraglen,icmp_param->csum); return 0; } /* * First fragment includes header. Note that we've done * the other fragments first, so that we get the checksum * for the whole packet here. */ csum = csum_partial_copy_nocheck((void *)&icmp_param->data, to, icmp_param->head_len, icmp_param->csum); csum=skb_copy_and_csum_bits(icmp_param->skb, icmp_param->offset, to+icmp_param->head_len, fraglen-icmp_param->head_len, csum); icmph=(struct icmphdr *)to; icmph->checksum = csum_fold(csum); return 0; } /* * 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 ipcm_cookie ipc; struct rtable *rt = (struct rtable*)skb->dst; u32 daddr; if (ip_options_echo(&icmp_param->replyopts, skb)) return; if (icmp_xmit_lock_bh()) return; icmp_param->data.icmph.checksum=0; icmp_param->csum=0; icmp_out_count(icmp_param->data.icmph.type); sk->protinfo.af_inet.tos = skb->nh.iph->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; } if (ip_route_output(&rt, daddr, rt->rt_spec_dst, RT_TOS(skb->nh.iph->tos), 0)) goto out; if (icmpv4_xrlim_allow(rt, icmp_param->data.icmph.type, icmp_param->data.icmph.code)) { ip_build_xmit(sk, icmp_glue_bits, icmp_param, icmp_param->data_len+icmp_param->head_len, &ipc, rt, MSG_DONTWAIT); } ip_rt_put(rt); out: icmp_xmit_unlock_bh(); } /* * 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, u32 info) { struct iphdr *iph; int room; struct icmp_bxm icmp_param; struct rtable *rt = (struct rtable*)skb_in->dst; struct ipcm_cookie ipc; u32 saddr; u8 tos; if (!rt) return; /* * 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 = skb_in->nh.iph; if ((u8*)iph < skb_in->head || (u8*)(iph+1) > skb_in->tail) return; /* * No replies to physical multicast/broadcast */ if (skb_in->pkt_type!=PACKET_HOST) return; /* * Now check at the protocol level */ if (rt->rt_flags&(RTCF_BROADCAST|RTCF_MULTICAST)) return; /* * Only reply to fragment 0. We byte re-order the constant * mask for efficiency. */ if (iph->frag_off&htons(IP_OFFSET)) return; /* * 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; if (skb_copy_bits(skb_in, skb_in->nh.raw + (iph->ihl<<2) + offsetof(struct icmphdr, type) - skb_in->data, &inner_type, 1)) return; /* * Assume any unknown ICMP type is an error. This isn't * specified by the RFC, but think about it.. */ if (inner_type>NR_ICMP_TYPES || icmp_pointers[inner_type].error) return; } } if (icmp_xmit_lock()) return; /* * Construct source address and options. */ #ifdef CONFIG_IP_ROUTE_NAT /* * Restore original addresses if packet has been translated. */ if (rt->rt_flags&RTCF_NAT && IPCB(skb_in)->flags&IPSKB_TRANSLATED) { iph->daddr = rt->key.dst; iph->saddr = rt->key.src; } #endif saddr = iph->daddr; if (!(rt->rt_flags & RTCF_LOCAL)) saddr = 0; tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) | IPTOS_PREC_INTERNETCONTROL) : iph->tos; if (ip_route_output(&rt, iph->saddr, saddr, RT_TOS(tos), 0)) goto out; if (ip_options_echo(&icmp_param.replyopts, skb_in)) goto ende; /* * 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.csum=0; icmp_param.skb=skb_in; icmp_param.offset=skb_in->nh.raw - skb_in->data; icmp_out_count(icmp_param.data.icmph.type); icmp_socket->sk->protinfo.af_inet.tos = tos; ipc.addr = iph->saddr; ipc.opt = &icmp_param.replyopts; if (icmp_param.replyopts.srr) { ip_rt_put(rt); if (ip_route_output(&rt, icmp_param.replyopts.faddr, saddr, RT_TOS(tos), 0)) goto out; } if (!icmpv4_xrlim_allow(rt, type, code)) goto ende; /* RFC says return as much as we can without exceeding 576 bytes. */ room = rt->u.dst.pmtu; 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); ip_build_xmit(icmp_socket->sk, icmp_glue_bits, &icmp_param, icmp_param.data_len+sizeof(struct icmphdr), &ipc, rt, MSG_DONTWAIT); ende: ip_rt_put(rt); out: icmp_xmit_unlock(); } /* * 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 inet_protocol *ipprot; struct sock *raw_sk; u32 info = 0; /* * 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))) { ICMP_INC_STATS_BH(IcmpInErrors); return; } icmph = skb->h.icmph; iph = (struct iphdr *) skb->data; if (iph->ihl<5) { /* Mangled header, drop. */ ICMP_INC_STATS_BH(IcmpInErrors); return; } if(icmph->type==ICMP_DEST_UNREACH) { switch(icmph->code & 15) { case ICMP_NET_UNREACH: break; case ICMP_HOST_UNREACH: break; case ICMP_PROT_UNREACH: break; case ICMP_PORT_UNREACH: break; case ICMP_FRAG_NEEDED: if (ipv4_config.no_pmtu_disc) { if (net_ratelimit()) printk(KERN_INFO "ICMP: %u.%u.%u.%u: fragmentation needed and DF set.\n", NIPQUAD(iph->daddr)); } else { info = ip_rt_frag_needed(iph, ntohs(icmph->un.frag.mtu)); if (!info) goto out; } break; case ICMP_SR_FAILED: if (net_ratelimit()) printk(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) { if (inet_addr_type(iph->daddr) == RTN_BROADCAST) { if (net_ratelimit()) printk(KERN_WARNING "%u.%u.%u.%u sent an invalid ICMP error to a broadcast.\n", NIPQUAD(skb->nh.iph->saddr)); 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? */ /* Note: See raw.c and net/raw.h, RAWV4_HTABLE_SIZE==MAX_INET_PROTOS */ hash = protocol & (MAX_INET_PROTOS - 1); read_lock(&raw_v4_lock); if ((raw_sk = raw_v4_htable[hash]) != NULL) { while ((raw_sk = __raw_v4_lookup(raw_sk, protocol, iph->daddr, iph->saddr, skb->dev->ifindex)) != NULL) { raw_err(raw_sk, skb, info); raw_sk = raw_sk->next; iph = (struct iphdr *)skb->data; } } read_unlock(&raw_v4_lock); /* * This can't change while we are doing it. * Callers have obtained BR_NETPROTO_LOCK so * we are OK. */ ipprot = (struct inet_protocol *) inet_protos[hash]; while (ipprot) { struct inet_protocol *nextip; nextip = (struct inet_protocol *) ipprot->next; /* * Pass it off to everyone who wants it. */ /* RFC1122: OK. Passes appropriate ICMP errors to the */ /* appropriate protocol layer (MUST), as per 3.2.2. */ if (protocol == ipprot->protocol && ipprot->err_handler) ipprot->err_handler(skb, info); ipprot = nextip; } out:; } /* * Handle ICMP_REDIRECT. */ static void icmp_redirect(struct sk_buff *skb) { struct iphdr *iph; unsigned long ip; if (skb->len < sizeof(struct iphdr)) { ICMP_INC_STATS_BH(IcmpInErrors); return; } /* * Get the copied header of the packet that caused the redirect */ if (!pskb_may_pull(skb, sizeof(struct iphdr))) return; iph = (struct iphdr *) skb->data; ip = iph->daddr; switch (skb->h.icmph->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(skb->nh.iph->saddr, ip, skb->h.icmph->un.gateway, iph->saddr, iph->tos, skb->dev); break; default: break; } } /* * 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=*skb->h.icmph; 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) { ICMP_INC_STATS_BH(IcmpInErrors); return; } /* * 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=*skb->h.icmph; 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); } /* * 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; u32 mask; if (skb->len < 4 || !(rt->rt_flags&RTCF_DIRECTSRC)) return; in_dev = in_dev_get(dev); if (!in_dev) return; read_lock(&in_dev->lock); if (in_dev->ifa_list && IN_DEV_LOG_MARTIANS(in_dev) && IN_DEV_FORWARD(in_dev)) { if (skb_copy_bits(skb, 0, &mask, 4)) BUG(); for (ifa=in_dev->ifa_list; ifa; ifa = ifa->ifa_next) { if (mask == 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(mask), dev->name, NIPQUAD(rt->rt_src)); } } read_unlock(&in_dev->lock); in_dev_put(in_dev); } static void icmp_discard(struct sk_buff *skb) { } /* * Deal with incoming ICMP packets. */ int icmp_rcv(struct sk_buff *skb) { struct icmphdr *icmph = skb->h.icmph; struct rtable *rt = (struct rtable*)skb->dst; ICMP_INC_STATS_BH(IcmpInMsgs); switch (skb->ip_summed) { case CHECKSUM_HW: if ((u16)csum_fold(skb->csum) == 0) break; NETDEBUG(if (net_ratelimit()) printk(KERN_DEBUG "icmp v4 hw csum failure\n")); case CHECKSUM_NONE: if ((u16)csum_fold(skb_checksum(skb, 0, skb->len, 0))) goto error; default:; } if (!pskb_pull(skb, sizeof(struct icmphdr))) goto error; /* * 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 && 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].input[smp_processor_id()*2*sizeof(struct icmp_mib)/sizeof(unsigned long)]++; (icmp_pointers[icmph->type].handler)(skb); drop: kfree_skb(skb); return 0; error: ICMP_INC_STATS_BH(IcmpInErrors); goto drop; } /* * This table is the definition of how we handle ICMP. */ static struct icmp_control icmp_pointers[NR_ICMP_TYPES+1] = { /* ECHO REPLY (0) */ { &icmp_statistics[0].IcmpOutEchoReps, &icmp_statistics[0].IcmpInEchoReps, icmp_discard, 0 }, { &icmp_statistics[0].dummy, &icmp_statistics[0].IcmpInErrors, icmp_discard, 1 }, { &icmp_statistics[0].dummy, &icmp_statistics[0].IcmpInErrors, icmp_discard, 1 }, /* DEST UNREACH (3) */ { &icmp_statistics[0].IcmpOutDestUnreachs, &icmp_statistics[0].IcmpInDestUnreachs, icmp_unreach, 1 }, /* SOURCE QUENCH (4) */ { &icmp_statistics[0].IcmpOutSrcQuenchs, &icmp_statistics[0].IcmpInSrcQuenchs, icmp_unreach, 1 }, /* REDIRECT (5) */ { &icmp_statistics[0].IcmpOutRedirects, &icmp_statistics[0].IcmpInRedirects, icmp_redirect, 1 }, { &icmp_statistics[0].dummy, &icmp_statistics[0].IcmpInErrors, icmp_discard, 1 }, { &icmp_statistics[0].dummy, &icmp_statistics[0].IcmpInErrors, icmp_discard, 1 }, /* ECHO (8) */ { &icmp_statistics[0].IcmpOutEchos, &icmp_statistics[0].IcmpInEchos, icmp_echo, 0 }, { &icmp_statistics[0].dummy, &icmp_statistics[0].IcmpInErrors, icmp_discard, 1 }, { &icmp_statistics[0].dummy, &icmp_statistics[0].IcmpInErrors, icmp_discard, 1 }, /* TIME EXCEEDED (11) */ { &icmp_statistics[0].IcmpOutTimeExcds, &icmp_statistics[0].IcmpInTimeExcds, icmp_unreach, 1 }, /* PARAMETER PROBLEM (12) */ { &icmp_statistics[0].IcmpOutParmProbs, &icmp_statistics[0].IcmpInParmProbs, icmp_unreach, 1 }, /* TIMESTAMP (13) */ { &icmp_statistics[0].IcmpOutTimestamps, &icmp_statistics[0].IcmpInTimestamps, icmp_timestamp, 0 }, /* TIMESTAMP REPLY (14) */ { &icmp_statistics[0].IcmpOutTimestampReps, &icmp_statistics[0].IcmpInTimestampReps, icmp_discard, 0 }, /* INFO (15) */ { &icmp_statistics[0].dummy, &icmp_statistics[0].dummy, icmp_discard, 0 }, /* INFO REPLY (16) */ { &icmp_statistics[0].dummy, &icmp_statistics[0].dummy, icmp_discard, 0 }, /* ADDR MASK (17) */ { &icmp_statistics[0].IcmpOutAddrMasks, &icmp_statistics[0].IcmpInAddrMasks, icmp_address, 0 }, /* ADDR MASK REPLY (18) */ { &icmp_statistics[0].IcmpOutAddrMaskReps, &icmp_statistics[0].IcmpInAddrMaskReps, icmp_address_reply, 0 } }; void __init icmp_init(struct net_proto_family *ops) { int err; icmp_inode.i_mode = S_IFSOCK; icmp_inode.i_sock = 1; icmp_inode.i_uid = 0; icmp_inode.i_gid = 0; init_waitqueue_head(&icmp_inode.i_wait); init_waitqueue_head(&icmp_inode.u.socket_i.wait); icmp_socket->inode = &icmp_inode; icmp_socket->state = SS_UNCONNECTED; icmp_socket->type=SOCK_RAW; if ((err=ops->create(icmp_socket, IPPROTO_ICMP))<0) panic("Failed to create the ICMP control socket.\n"); icmp_socket->sk->allocation=GFP_ATOMIC; icmp_socket->sk->sndbuf = SK_WMEM_MAX*2; icmp_socket->sk->protinfo.af_inet.ttl = MAXTTL; icmp_socket->sk->protinfo.af_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. */ icmp_socket->sk->prot->unhash(icmp_socket->sk); }