From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sat, 16 Apr 2005 15:20:36 -0700 Subject: Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip! --- net/ipv4/icmp.c | 1143 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 1143 insertions(+) create mode 100644 net/ipv4/icmp.c (limited to 'net/ipv4/icmp.c') diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c new file mode 100644 index 00000000000..85bf0d3e294 --- /dev/null +++ b/net/ipv4/icmp.c @@ -0,0 +1,1143 @@ +/* + * NET3: Implementation of the ICMP protocol layer. + * + * Alan Cox, + * + * 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 +#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; + + struct { + struct icmphdr icmph; + __u32 times[3]; + } data; + int head_len; + struct ip_options replyopts; + unsigned char optbuf[40]; +}; + +/* + * Statistics + */ +DEFINE_SNMP_STAT(struct icmp_mib, icmp_statistics); + +/* 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; +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 { + int output_entry; /* Field for increment on output */ + int input_entry; /* Field for 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(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 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; + int rc = 0; + + 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; + rc = 1; + } + 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 + */ +static void icmp_out_count(int type) +{ + if (type <= NR_ICMP_TYPES) { + ICMP_INC_STATS(icmp_pointers[type].output_entry); + 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; + unsigned int 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; + + 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); + + if ((skb = skb_peek(&icmp_socket->sk->sk_write_queue)) != NULL) { + struct icmphdr *icmph = skb->h.icmph; + unsigned int 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; + u32 daddr; + + if (ip_options_echo(&icmp_param->replyopts, skb)) + goto out; + + if (icmp_xmit_lock()) + return; + + icmp_param->data.icmph.checksum = 0; + icmp_out_count(icmp_param->data.icmph.type); + + 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; + } + { + struct flowi fl = { .nl_u = { .ip4_u = + { .daddr = daddr, + .saddr = rt->rt_spec_dst, + .tos = RT_TOS(skb->nh.iph->tos) } }, + .proto = IPPROTO_ICMP }; + if (ip_route_output_key(&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(); +out:; +} + + +/* + * 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) + goto out; + + /* + * 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) + 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_in->nh.raw + + (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)) + 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 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.skb = skb_in; + icmp_param.offset = skb_in->nh.raw - skb_in->data; + icmp_out_count(icmp_param.data.icmph.type); + 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 + } + } + }; + if (ip_route_output_key(&rt, &fl)) + goto out_unlock; + } + + 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; + 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))) + goto out_err; + + icmph = skb->h.icmph; + 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( + 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: + LIMIT_NETDEBUG( + 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 && + inet_addr_type(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(skb->nh.iph->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? + */ + + /* 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 = sk_head(&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 = sk_next(raw_sk); + iph = (struct iphdr *)skb->data; + } + } + read_unlock(&raw_v4_lock); + + 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; + unsigned long ip; + + 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; + 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; + } +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 = *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) + 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 = *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); +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)) { + u32 _mask, *mp; + + mp = skb_header_pointer(skb, 0, sizeof(_mask), &_mask); + if (mp == NULL) + BUG(); + 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; + + ICMP_INC_STATS_BH(ICMP_MIB_INMSGS); + + switch (skb->ip_summed) { + case CHECKSUM_HW: + if (!(u16)csum_fold(skb->csum)) + 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; + + icmph = skb->h.icmph; + + /* + * 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_INC_STATS_BH(icmp_pointers[icmph->type].input_entry); + 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 struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = { + [ICMP_ECHOREPLY] = { + .output_entry = ICMP_MIB_OUTECHOREPS, + .input_entry = ICMP_MIB_INECHOREPS, + .handler = icmp_discard, + }, + [1] = { + .output_entry = ICMP_MIB_DUMMY, + .input_entry = ICMP_MIB_INERRORS, + .handler = icmp_discard, + .error = 1, + }, + [2] = { + .output_entry = ICMP_MIB_DUMMY, + .input_entry = ICMP_MIB_INERRORS, + .handler = icmp_discard, + .error = 1, + }, + [ICMP_DEST_UNREACH] = { + .output_entry = ICMP_MIB_OUTDESTUNREACHS, + .input_entry = ICMP_MIB_INDESTUNREACHS, + .handler = icmp_unreach, + .error = 1, + }, + [ICMP_SOURCE_QUENCH] = { + .output_entry = ICMP_MIB_OUTSRCQUENCHS, + .input_entry = ICMP_MIB_INSRCQUENCHS, + .handler = icmp_unreach, + .error = 1, + }, + [ICMP_REDIRECT] = { + .output_entry = ICMP_MIB_OUTREDIRECTS, + .input_entry = ICMP_MIB_INREDIRECTS, + .handler = icmp_redirect, + .error = 1, + }, + [6] = { + .output_entry = ICMP_MIB_DUMMY, + .input_entry = ICMP_MIB_INERRORS, + .handler = icmp_discard, + .error = 1, + }, + [7] = { + .output_entry = ICMP_MIB_DUMMY, + .input_entry = ICMP_MIB_INERRORS, + .handler = icmp_discard, + .error = 1, + }, + [ICMP_ECHO] = { + .output_entry = ICMP_MIB_OUTECHOS, + .input_entry = ICMP_MIB_INECHOS, + .handler = icmp_echo, + }, + [9] = { + .output_entry = ICMP_MIB_DUMMY, + .input_entry = ICMP_MIB_INERRORS, + .handler = icmp_discard, + .error = 1, + }, + [10] = { + .output_entry = ICMP_MIB_DUMMY, + .input_entry = ICMP_MIB_INERRORS, + .handler = icmp_discard, + .error = 1, + }, + [ICMP_TIME_EXCEEDED] = { + .output_entry = ICMP_MIB_OUTTIMEEXCDS, + .input_entry = ICMP_MIB_INTIMEEXCDS, + .handler = icmp_unreach, + .error = 1, + }, + [ICMP_PARAMETERPROB] = { + .output_entry = ICMP_MIB_OUTPARMPROBS, + .input_entry = ICMP_MIB_INPARMPROBS, + .handler = icmp_unreach, + .error = 1, + }, + [ICMP_TIMESTAMP] = { + .output_entry = ICMP_MIB_OUTTIMESTAMPS, + .input_entry = ICMP_MIB_INTIMESTAMPS, + .handler = icmp_timestamp, + }, + [ICMP_TIMESTAMPREPLY] = { + .output_entry = ICMP_MIB_OUTTIMESTAMPREPS, + .input_entry = ICMP_MIB_INTIMESTAMPREPS, + .handler = icmp_discard, + }, + [ICMP_INFO_REQUEST] = { + .output_entry = ICMP_MIB_DUMMY, + .input_entry = ICMP_MIB_DUMMY, + .handler = icmp_discard, + }, + [ICMP_INFO_REPLY] = { + .output_entry = ICMP_MIB_DUMMY, + .input_entry = ICMP_MIB_DUMMY, + .handler = icmp_discard, + }, + [ICMP_ADDRESS] = { + .output_entry = ICMP_MIB_OUTADDRMASKS, + .input_entry = ICMP_MIB_INADDRMASKS, + .handler = icmp_address, + }, + [ICMP_ADDRESSREPLY] = { + .output_entry = ICMP_MIB_OUTADDRMASKREPS, + .input_entry = ICMP_MIB_INADDRMASKREPS, + .handler = icmp_address_reply, + }, +}; + +void __init icmp_init(struct net_proto_family *ops) +{ + struct inet_sock *inet; + int i; + + for (i = 0; i < NR_CPUS; i++) { + int err; + + if (!cpu_possible(i)) + continue; + + 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); -- cgit v1.2.3