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v3.15
   1/*
   2 *	NET3:	Implementation of the ICMP protocol layer.
   3 *
   4 *		Alan Cox, <alan@lxorguk.ukuu.org.uk>
   5 *
   6 *	This program is free software; you can redistribute it and/or
   7 *	modify it under the terms of the GNU General Public License
   8 *	as published by the Free Software Foundation; either version
   9 *	2 of the License, or (at your option) any later version.
  10 *
  11 *	Some of the function names and the icmp unreach table for this
  12 *	module were derived from [icmp.c 1.0.11 06/02/93] by
  13 *	Ross Biro, Fred N. van Kempen, Mark Evans, Alan Cox, Gerhard Koerting.
  14 *	Other than that this module is a complete rewrite.
  15 *
  16 *	Fixes:
  17 *	Clemens Fruhwirth	:	introduce global icmp rate limiting
  18 *					with icmp type masking ability instead
  19 *					of broken per type icmp timeouts.
  20 *		Mike Shaver	:	RFC1122 checks.
  21 *		Alan Cox	:	Multicast ping reply as self.
  22 *		Alan Cox	:	Fix atomicity lockup in ip_build_xmit
  23 *					call.
  24 *		Alan Cox	:	Added 216,128 byte paths to the MTU
  25 *					code.
  26 *		Martin Mares	:	RFC1812 checks.
  27 *		Martin Mares	:	Can be configured to follow redirects
  28 *					if acting as a router _without_ a
  29 *					routing protocol (RFC 1812).
  30 *		Martin Mares	:	Echo requests may be configured to
  31 *					be ignored (RFC 1812).
  32 *		Martin Mares	:	Limitation of ICMP error message
  33 *					transmit rate (RFC 1812).
  34 *		Martin Mares	:	TOS and Precedence set correctly
  35 *					(RFC 1812).
  36 *		Martin Mares	:	Now copying as much data from the
  37 *					original packet as we can without
  38 *					exceeding 576 bytes (RFC 1812).
  39 *	Willy Konynenberg	:	Transparent proxying support.
  40 *		Keith Owens	:	RFC1191 correction for 4.2BSD based
  41 *					path MTU bug.
  42 *		Thomas Quinot	:	ICMP Dest Unreach codes up to 15 are
  43 *					valid (RFC 1812).
  44 *		Andi Kleen	:	Check all packet lengths properly
  45 *					and moved all kfree_skb() up to
  46 *					icmp_rcv.
  47 *		Andi Kleen	:	Move the rate limit bookkeeping
  48 *					into the dest entry and use a token
  49 *					bucket filter (thanks to ANK). Make
  50 *					the rates sysctl configurable.
  51 *		Yu Tianli	:	Fixed two ugly bugs in icmp_send
  52 *					- IP option length was accounted wrongly
  53 *					- ICMP header length was not accounted
  54 *					  at all.
  55 *              Tristan Greaves :       Added sysctl option to ignore bogus
  56 *              			broadcast responses from broken routers.
  57 *
  58 * To Fix:
  59 *
  60 *	- Should use skb_pull() instead of all the manual checking.
  61 *	  This would also greatly simply some upper layer error handlers. --AK
  62 *
  63 */
  64
  65#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  66
  67#include <linux/module.h>
  68#include <linux/types.h>
  69#include <linux/jiffies.h>
  70#include <linux/kernel.h>
  71#include <linux/fcntl.h>
  72#include <linux/socket.h>
  73#include <linux/in.h>
  74#include <linux/inet.h>
  75#include <linux/inetdevice.h>
  76#include <linux/netdevice.h>
  77#include <linux/string.h>
  78#include <linux/netfilter_ipv4.h>
  79#include <linux/slab.h>
  80#include <net/snmp.h>
  81#include <net/ip.h>
  82#include <net/route.h>
  83#include <net/protocol.h>
  84#include <net/icmp.h>
  85#include <net/tcp.h>
  86#include <net/udp.h>
  87#include <net/raw.h>
  88#include <net/ping.h>
  89#include <linux/skbuff.h>
  90#include <net/sock.h>
  91#include <linux/errno.h>
  92#include <linux/timer.h>
  93#include <linux/init.h>
  94#include <asm/uaccess.h>
  95#include <net/checksum.h>
  96#include <net/xfrm.h>
  97#include <net/inet_common.h>
  98#include <net/ip_fib.h>
 
  99
 100/*
 101 *	Build xmit assembly blocks
 102 */
 103
 104struct icmp_bxm {
 105	struct sk_buff *skb;
 106	int offset;
 107	int data_len;
 108
 109	struct {
 110		struct icmphdr icmph;
 111		__be32	       times[3];
 112	} data;
 113	int head_len;
 114	struct ip_options_data replyopts;
 115};
 116
 117/* An array of errno for error messages from dest unreach. */
 118/* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */
 119
 120const struct icmp_err icmp_err_convert[] = {
 121	{
 122		.errno = ENETUNREACH,	/* ICMP_NET_UNREACH */
 123		.fatal = 0,
 124	},
 125	{
 126		.errno = EHOSTUNREACH,	/* ICMP_HOST_UNREACH */
 127		.fatal = 0,
 128	},
 129	{
 130		.errno = ENOPROTOOPT	/* ICMP_PROT_UNREACH */,
 131		.fatal = 1,
 132	},
 133	{
 134		.errno = ECONNREFUSED,	/* ICMP_PORT_UNREACH */
 135		.fatal = 1,
 136	},
 137	{
 138		.errno = EMSGSIZE,	/* ICMP_FRAG_NEEDED */
 139		.fatal = 0,
 140	},
 141	{
 142		.errno = EOPNOTSUPP,	/* ICMP_SR_FAILED */
 143		.fatal = 0,
 144	},
 145	{
 146		.errno = ENETUNREACH,	/* ICMP_NET_UNKNOWN */
 147		.fatal = 1,
 148	},
 149	{
 150		.errno = EHOSTDOWN,	/* ICMP_HOST_UNKNOWN */
 151		.fatal = 1,
 152	},
 153	{
 154		.errno = ENONET,	/* ICMP_HOST_ISOLATED */
 155		.fatal = 1,
 156	},
 157	{
 158		.errno = ENETUNREACH,	/* ICMP_NET_ANO	*/
 159		.fatal = 1,
 160	},
 161	{
 162		.errno = EHOSTUNREACH,	/* ICMP_HOST_ANO */
 163		.fatal = 1,
 164	},
 165	{
 166		.errno = ENETUNREACH,	/* ICMP_NET_UNR_TOS */
 167		.fatal = 0,
 168	},
 169	{
 170		.errno = EHOSTUNREACH,	/* ICMP_HOST_UNR_TOS */
 171		.fatal = 0,
 172	},
 173	{
 174		.errno = EHOSTUNREACH,	/* ICMP_PKT_FILTERED */
 175		.fatal = 1,
 176	},
 177	{
 178		.errno = EHOSTUNREACH,	/* ICMP_PREC_VIOLATION */
 179		.fatal = 1,
 180	},
 181	{
 182		.errno = EHOSTUNREACH,	/* ICMP_PREC_CUTOFF */
 183		.fatal = 1,
 184	},
 185};
 186EXPORT_SYMBOL(icmp_err_convert);
 187
 188/*
 189 *	ICMP control array. This specifies what to do with each ICMP.
 190 */
 191
 192struct icmp_control {
 193	void (*handler)(struct sk_buff *skb);
 194	short   error;		/* This ICMP is classed as an error message */
 195};
 196
 197static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1];
 198
 199/*
 200 *	The ICMP socket(s). This is the most convenient way to flow control
 201 *	our ICMP output as well as maintain a clean interface throughout
 202 *	all layers. All Socketless IP sends will soon be gone.
 203 *
 204 *	On SMP we have one ICMP socket per-cpu.
 205 */
 206static struct sock *icmp_sk(struct net *net)
 207{
 208	return net->ipv4.icmp_sk[smp_processor_id()];
 209}
 210
 
 211static inline struct sock *icmp_xmit_lock(struct net *net)
 212{
 213	struct sock *sk;
 214
 215	local_bh_disable();
 216
 217	sk = icmp_sk(net);
 218
 219	if (unlikely(!spin_trylock(&sk->sk_lock.slock))) {
 220		/* This can happen if the output path signals a
 221		 * dst_link_failure() for an outgoing ICMP packet.
 222		 */
 223		local_bh_enable();
 224		return NULL;
 225	}
 226	return sk;
 227}
 228
 229static inline void icmp_xmit_unlock(struct sock *sk)
 230{
 231	spin_unlock_bh(&sk->sk_lock.slock);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 232}
 233
 234/*
 235 *	Send an ICMP frame.
 236 */
 237
 238static inline bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt,
 239				      struct flowi4 *fl4, int type, int code)
 240{
 241	struct dst_entry *dst = &rt->dst;
 
 242	bool rc = true;
 
 243
 244	if (type > NR_ICMP_TYPES)
 245		goto out;
 246
 247	/* Don't limit PMTU discovery. */
 248	if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
 249		goto out;
 250
 251	/* No rate limit on loopback */
 252	if (dst->dev && (dst->dev->flags&IFF_LOOPBACK))
 253		goto out;
 254
 255	/* Limit if icmp type is enabled in ratemask. */
 256	if ((1 << type) & net->ipv4.sysctl_icmp_ratemask) {
 257		struct inet_peer *peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, 1);
 258		rc = inet_peer_xrlim_allow(peer,
 259					   net->ipv4.sysctl_icmp_ratelimit);
 260		if (peer)
 261			inet_putpeer(peer);
 262	}
 263out:
 264	return rc;
 265}
 266
 267/*
 268 *	Maintain the counters used in the SNMP statistics for outgoing ICMP
 269 */
 270void icmp_out_count(struct net *net, unsigned char type)
 271{
 272	ICMPMSGOUT_INC_STATS(net, type);
 273	ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS);
 274}
 275
 276/*
 277 *	Checksum each fragment, and on the first include the headers and final
 278 *	checksum.
 279 */
 280static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd,
 281			  struct sk_buff *skb)
 282{
 283	struct icmp_bxm *icmp_param = (struct icmp_bxm *)from;
 284	__wsum csum;
 285
 286	csum = skb_copy_and_csum_bits(icmp_param->skb,
 287				      icmp_param->offset + offset,
 288				      to, len, 0);
 289
 290	skb->csum = csum_block_add(skb->csum, csum, odd);
 291	if (icmp_pointers[icmp_param->data.icmph.type].error)
 292		nf_ct_attach(skb, icmp_param->skb);
 293	return 0;
 294}
 295
 296static void icmp_push_reply(struct icmp_bxm *icmp_param,
 297			    struct flowi4 *fl4,
 298			    struct ipcm_cookie *ipc, struct rtable **rt)
 299{
 300	struct sock *sk;
 301	struct sk_buff *skb;
 302
 303	sk = icmp_sk(dev_net((*rt)->dst.dev));
 304	if (ip_append_data(sk, fl4, icmp_glue_bits, icmp_param,
 305			   icmp_param->data_len+icmp_param->head_len,
 306			   icmp_param->head_len,
 307			   ipc, rt, MSG_DONTWAIT) < 0) {
 308		ICMP_INC_STATS_BH(sock_net(sk), ICMP_MIB_OUTERRORS);
 309		ip_flush_pending_frames(sk);
 310	} else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
 311		struct icmphdr *icmph = icmp_hdr(skb);
 312		__wsum csum = 0;
 313		struct sk_buff *skb1;
 314
 315		skb_queue_walk(&sk->sk_write_queue, skb1) {
 316			csum = csum_add(csum, skb1->csum);
 317		}
 318		csum = csum_partial_copy_nocheck((void *)&icmp_param->data,
 319						 (char *)icmph,
 320						 icmp_param->head_len, csum);
 321		icmph->checksum = csum_fold(csum);
 322		skb->ip_summed = CHECKSUM_NONE;
 323		ip_push_pending_frames(sk, fl4);
 324	}
 325}
 326
 327/*
 328 *	Driving logic for building and sending ICMP messages.
 329 */
 330
 331static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
 332{
 333	struct ipcm_cookie ipc;
 334	struct rtable *rt = skb_rtable(skb);
 335	struct net *net = dev_net(rt->dst.dev);
 336	struct flowi4 fl4;
 337	struct sock *sk;
 338	struct inet_sock *inet;
 339	__be32 daddr, saddr;
 
 
 
 340
 341	if (ip_options_echo(&icmp_param->replyopts.opt.opt, skb))
 342		return;
 343
 
 
 
 
 
 
 
 344	sk = icmp_xmit_lock(net);
 345	if (sk == NULL)
 346		return;
 347	inet = inet_sk(sk);
 348
 349	icmp_param->data.icmph.checksum = 0;
 350
 351	inet->tos = ip_hdr(skb)->tos;
 
 352	daddr = ipc.addr = ip_hdr(skb)->saddr;
 353	saddr = fib_compute_spec_dst(skb);
 354	ipc.opt = NULL;
 355	ipc.tx_flags = 0;
 356	ipc.ttl = 0;
 357	ipc.tos = -1;
 358
 359	if (icmp_param->replyopts.opt.opt.optlen) {
 360		ipc.opt = &icmp_param->replyopts.opt;
 361		if (ipc.opt->opt.srr)
 362			daddr = icmp_param->replyopts.opt.opt.faddr;
 363	}
 364	memset(&fl4, 0, sizeof(fl4));
 365	fl4.daddr = daddr;
 366	fl4.saddr = saddr;
 
 
 367	fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos);
 368	fl4.flowi4_proto = IPPROTO_ICMP;
 
 369	security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
 370	rt = ip_route_output_key(net, &fl4);
 371	if (IS_ERR(rt))
 372		goto out_unlock;
 373	if (icmpv4_xrlim_allow(net, rt, &fl4, icmp_param->data.icmph.type,
 374			       icmp_param->data.icmph.code))
 375		icmp_push_reply(icmp_param, &fl4, &ipc, &rt);
 376	ip_rt_put(rt);
 377out_unlock:
 378	icmp_xmit_unlock(sk);
 
 
 379}
 380
 381static struct rtable *icmp_route_lookup(struct net *net,
 382					struct flowi4 *fl4,
 383					struct sk_buff *skb_in,
 384					const struct iphdr *iph,
 385					__be32 saddr, u8 tos,
 386					int type, int code,
 387					struct icmp_bxm *param)
 388{
 389	struct rtable *rt, *rt2;
 390	struct flowi4 fl4_dec;
 391	int err;
 392
 393	memset(fl4, 0, sizeof(*fl4));
 394	fl4->daddr = (param->replyopts.opt.opt.srr ?
 395		      param->replyopts.opt.opt.faddr : iph->saddr);
 396	fl4->saddr = saddr;
 
 
 397	fl4->flowi4_tos = RT_TOS(tos);
 398	fl4->flowi4_proto = IPPROTO_ICMP;
 399	fl4->fl4_icmp_type = type;
 400	fl4->fl4_icmp_code = code;
 
 
 401	security_skb_classify_flow(skb_in, flowi4_to_flowi(fl4));
 402	rt = __ip_route_output_key(net, fl4);
 403	if (IS_ERR(rt))
 404		return rt;
 405
 406	/* No need to clone since we're just using its address. */
 407	rt2 = rt;
 408
 409	rt = (struct rtable *) xfrm_lookup(net, &rt->dst,
 410					   flowi4_to_flowi(fl4), NULL, 0);
 411	if (!IS_ERR(rt)) {
 412		if (rt != rt2)
 413			return rt;
 414	} else if (PTR_ERR(rt) == -EPERM) {
 415		rt = NULL;
 416	} else
 417		return rt;
 418
 419	err = xfrm_decode_session_reverse(skb_in, flowi4_to_flowi(&fl4_dec), AF_INET);
 420	if (err)
 421		goto relookup_failed;
 422
 423	if (inet_addr_type(net, fl4_dec.saddr) == RTN_LOCAL) {
 
 424		rt2 = __ip_route_output_key(net, &fl4_dec);
 425		if (IS_ERR(rt2))
 426			err = PTR_ERR(rt2);
 427	} else {
 428		struct flowi4 fl4_2 = {};
 429		unsigned long orefdst;
 430
 431		fl4_2.daddr = fl4_dec.saddr;
 432		rt2 = ip_route_output_key(net, &fl4_2);
 433		if (IS_ERR(rt2)) {
 434			err = PTR_ERR(rt2);
 435			goto relookup_failed;
 436		}
 437		/* Ugh! */
 438		orefdst = skb_in->_skb_refdst; /* save old refdst */
 
 439		err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr,
 440				     RT_TOS(tos), rt2->dst.dev);
 441
 442		dst_release(&rt2->dst);
 443		rt2 = skb_rtable(skb_in);
 444		skb_in->_skb_refdst = orefdst; /* restore old refdst */
 445	}
 446
 447	if (err)
 448		goto relookup_failed;
 449
 450	rt2 = (struct rtable *) xfrm_lookup(net, &rt2->dst,
 451					    flowi4_to_flowi(&fl4_dec), NULL,
 452					    XFRM_LOOKUP_ICMP);
 453	if (!IS_ERR(rt2)) {
 454		dst_release(&rt->dst);
 455		memcpy(fl4, &fl4_dec, sizeof(*fl4));
 456		rt = rt2;
 457	} else if (PTR_ERR(rt2) == -EPERM) {
 458		if (rt)
 459			dst_release(&rt->dst);
 460		return rt2;
 461	} else {
 462		err = PTR_ERR(rt2);
 463		goto relookup_failed;
 464	}
 465	return rt;
 466
 467relookup_failed:
 468	if (rt)
 469		return rt;
 470	return ERR_PTR(err);
 471}
 472
 473/*
 474 *	Send an ICMP message in response to a situation
 475 *
 476 *	RFC 1122: 3.2.2	MUST send at least the IP header and 8 bytes of header.
 477 *		  MAY send more (we do).
 478 *			MUST NOT change this header information.
 479 *			MUST NOT reply to a multicast/broadcast IP address.
 480 *			MUST NOT reply to a multicast/broadcast MAC address.
 481 *			MUST reply to only the first fragment.
 482 */
 483
 484void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
 485{
 486	struct iphdr *iph;
 487	int room;
 488	struct icmp_bxm *icmp_param;
 489	struct rtable *rt = skb_rtable(skb_in);
 490	struct ipcm_cookie ipc;
 491	struct flowi4 fl4;
 492	__be32 saddr;
 493	u8  tos;
 
 494	struct net *net;
 495	struct sock *sk;
 496
 497	if (!rt)
 498		goto out;
 499	net = dev_net(rt->dst.dev);
 500
 501	/*
 502	 *	Find the original header. It is expected to be valid, of course.
 503	 *	Check this, icmp_send is called from the most obscure devices
 504	 *	sometimes.
 505	 */
 506	iph = ip_hdr(skb_in);
 507
 508	if ((u8 *)iph < skb_in->head ||
 509	    (skb_network_header(skb_in) + sizeof(*iph)) >
 510	    skb_tail_pointer(skb_in))
 511		goto out;
 512
 513	/*
 514	 *	No replies to physical multicast/broadcast
 515	 */
 516	if (skb_in->pkt_type != PACKET_HOST)
 517		goto out;
 518
 519	/*
 520	 *	Now check at the protocol level
 521	 */
 522	if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
 523		goto out;
 524
 525	/*
 526	 *	Only reply to fragment 0. We byte re-order the constant
 527	 *	mask for efficiency.
 528	 */
 529	if (iph->frag_off & htons(IP_OFFSET))
 530		goto out;
 531
 532	/*
 533	 *	If we send an ICMP error to an ICMP error a mess would result..
 534	 */
 535	if (icmp_pointers[type].error) {
 536		/*
 537		 *	We are an error, check if we are replying to an
 538		 *	ICMP error
 539		 */
 540		if (iph->protocol == IPPROTO_ICMP) {
 541			u8 _inner_type, *itp;
 542
 543			itp = skb_header_pointer(skb_in,
 544						 skb_network_header(skb_in) +
 545						 (iph->ihl << 2) +
 546						 offsetof(struct icmphdr,
 547							  type) -
 548						 skb_in->data,
 549						 sizeof(_inner_type),
 550						 &_inner_type);
 551			if (itp == NULL)
 552				goto out;
 553
 554			/*
 555			 *	Assume any unknown ICMP type is an error. This
 556			 *	isn't specified by the RFC, but think about it..
 557			 */
 558			if (*itp > NR_ICMP_TYPES ||
 559			    icmp_pointers[*itp].error)
 560				goto out;
 561		}
 562	}
 563
 564	icmp_param = kmalloc(sizeof(*icmp_param), GFP_ATOMIC);
 565	if (!icmp_param)
 566		return;
 
 
 
 
 
 
 
 567
 568	sk = icmp_xmit_lock(net);
 569	if (sk == NULL)
 570		goto out_free;
 571
 572	/*
 573	 *	Construct source address and options.
 574	 */
 575
 576	saddr = iph->daddr;
 577	if (!(rt->rt_flags & RTCF_LOCAL)) {
 578		struct net_device *dev = NULL;
 579
 580		rcu_read_lock();
 581		if (rt_is_input_route(rt) &&
 582		    net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)
 583			dev = dev_get_by_index_rcu(net, inet_iif(skb_in));
 584
 585		if (dev)
 586			saddr = inet_select_addr(dev, 0, RT_SCOPE_LINK);
 587		else
 588			saddr = 0;
 589		rcu_read_unlock();
 590	}
 591
 592	tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) |
 593					   IPTOS_PREC_INTERNETCONTROL) :
 594					  iph->tos;
 
 595
 596	if (ip_options_echo(&icmp_param->replyopts.opt.opt, skb_in))
 597		goto out_unlock;
 598
 599
 600	/*
 601	 *	Prepare data for ICMP header.
 602	 */
 603
 604	icmp_param->data.icmph.type	 = type;
 605	icmp_param->data.icmph.code	 = code;
 606	icmp_param->data.icmph.un.gateway = info;
 607	icmp_param->data.icmph.checksum	 = 0;
 608	icmp_param->skb	  = skb_in;
 609	icmp_param->offset = skb_network_offset(skb_in);
 610	inet_sk(sk)->tos = tos;
 
 611	ipc.addr = iph->saddr;
 612	ipc.opt = &icmp_param->replyopts.opt;
 613	ipc.tx_flags = 0;
 614	ipc.ttl = 0;
 615	ipc.tos = -1;
 616
 617	rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos,
 618			       type, code, icmp_param);
 619	if (IS_ERR(rt))
 620		goto out_unlock;
 621
 
 622	if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code))
 623		goto ende;
 624
 625	/* RFC says return as much as we can without exceeding 576 bytes. */
 626
 627	room = dst_mtu(&rt->dst);
 628	if (room > 576)
 629		room = 576;
 630	room -= sizeof(struct iphdr) + icmp_param->replyopts.opt.opt.optlen;
 631	room -= sizeof(struct icmphdr);
 632
 633	icmp_param->data_len = skb_in->len - icmp_param->offset;
 634	if (icmp_param->data_len > room)
 635		icmp_param->data_len = room;
 636	icmp_param->head_len = sizeof(struct icmphdr);
 637
 638	icmp_push_reply(icmp_param, &fl4, &ipc, &rt);
 639ende:
 640	ip_rt_put(rt);
 641out_unlock:
 642	icmp_xmit_unlock(sk);
 643out_free:
 644	kfree(icmp_param);
 645out:;
 646}
 647EXPORT_SYMBOL(icmp_send);
 648
 649
 650static void icmp_socket_deliver(struct sk_buff *skb, u32 info)
 651{
 652	const struct iphdr *iph = (const struct iphdr *) skb->data;
 653	const struct net_protocol *ipprot;
 654	int protocol = iph->protocol;
 655
 656	/* Checkin full IP header plus 8 bytes of protocol to
 657	 * avoid additional coding at protocol handlers.
 658	 */
 659	if (!pskb_may_pull(skb, iph->ihl * 4 + 8))
 
 660		return;
 
 661
 662	raw_icmp_error(skb, protocol, info);
 663
 664	rcu_read_lock();
 665	ipprot = rcu_dereference(inet_protos[protocol]);
 666	if (ipprot && ipprot->err_handler)
 667		ipprot->err_handler(skb, info);
 668	rcu_read_unlock();
 669}
 670
 671static bool icmp_tag_validation(int proto)
 672{
 673	bool ok;
 674
 675	rcu_read_lock();
 676	ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation;
 677	rcu_read_unlock();
 678	return ok;
 679}
 680
 681/*
 682 *	Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEED, ICMP_QUENCH, and
 683 *	ICMP_PARAMETERPROB.
 684 */
 685
 686static void icmp_unreach(struct sk_buff *skb)
 687{
 688	const struct iphdr *iph;
 689	struct icmphdr *icmph;
 690	struct net *net;
 691	u32 info = 0;
 692
 693	net = dev_net(skb_dst(skb)->dev);
 694
 695	/*
 696	 *	Incomplete header ?
 697	 * 	Only checks for the IP header, there should be an
 698	 *	additional check for longer headers in upper levels.
 699	 */
 700
 701	if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 702		goto out_err;
 703
 704	icmph = icmp_hdr(skb);
 705	iph   = (const struct iphdr *)skb->data;
 706
 707	if (iph->ihl < 5) /* Mangled header, drop. */
 708		goto out_err;
 709
 710	if (icmph->type == ICMP_DEST_UNREACH) {
 
 711		switch (icmph->code & 15) {
 712		case ICMP_NET_UNREACH:
 713		case ICMP_HOST_UNREACH:
 714		case ICMP_PROT_UNREACH:
 715		case ICMP_PORT_UNREACH:
 716			break;
 717		case ICMP_FRAG_NEEDED:
 718			/* for documentation of the ip_no_pmtu_disc
 719			 * values please see
 720			 * Documentation/networking/ip-sysctl.txt
 721			 */
 722			switch (net->ipv4.sysctl_ip_no_pmtu_disc) {
 723			default:
 724				LIMIT_NETDEBUG(KERN_INFO pr_fmt("%pI4: fragmentation needed and DF set\n"),
 725					       &iph->daddr);
 726				break;
 727			case 2:
 728				goto out;
 729			case 3:
 730				if (!icmp_tag_validation(iph->protocol))
 731					goto out;
 732				/* fall through */
 733			case 0:
 734				info = ntohs(icmph->un.frag.mtu);
 735				if (!info)
 736					goto out;
 737			}
 738			break;
 739		case ICMP_SR_FAILED:
 740			LIMIT_NETDEBUG(KERN_INFO pr_fmt("%pI4: Source Route Failed\n"),
 741				       &iph->daddr);
 742			break;
 743		default:
 744			break;
 745		}
 746		if (icmph->code > NR_ICMP_UNREACH)
 747			goto out;
 748	} else if (icmph->type == ICMP_PARAMETERPROB)
 
 749		info = ntohl(icmph->un.gateway) >> 24;
 
 
 
 
 
 
 
 750
 751	/*
 752	 *	Throw it at our lower layers
 753	 *
 754	 *	RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
 755	 *		  header.
 756	 *	RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
 757	 *		  transport layer.
 758	 *	RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
 759	 *		  transport layer.
 760	 */
 761
 762	/*
 763	 *	Check the other end isn't violating RFC 1122. Some routers send
 764	 *	bogus responses to broadcast frames. If you see this message
 765	 *	first check your netmask matches at both ends, if it does then
 766	 *	get the other vendor to fix their kit.
 767	 */
 768
 769	if (!net->ipv4.sysctl_icmp_ignore_bogus_error_responses &&
 770	    inet_addr_type(net, iph->daddr) == RTN_BROADCAST) {
 771		net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n",
 772				     &ip_hdr(skb)->saddr,
 773				     icmph->type, icmph->code,
 774				     &iph->daddr, skb->dev->name);
 775		goto out;
 776	}
 777
 778	icmp_socket_deliver(skb, info);
 779
 780out:
 781	return;
 782out_err:
 783	ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
 784	goto out;
 785}
 786
 787
 788/*
 789 *	Handle ICMP_REDIRECT.
 790 */
 791
 792static void icmp_redirect(struct sk_buff *skb)
 793{
 794	if (skb->len < sizeof(struct iphdr)) {
 795		ICMP_INC_STATS_BH(dev_net(skb->dev), ICMP_MIB_INERRORS);
 796		return;
 797	}
 798
 799	if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 800		return;
 
 
 801
 802	icmp_socket_deliver(skb, icmp_hdr(skb)->un.gateway);
 
 803}
 804
 805/*
 806 *	Handle ICMP_ECHO ("ping") requests.
 807 *
 808 *	RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
 809 *		  requests.
 810 *	RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
 811 *		  included in the reply.
 812 *	RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
 813 *		  echo requests, MUST have default=NOT.
 814 *	See also WRT handling of options once they are done and working.
 815 */
 816
 817static void icmp_echo(struct sk_buff *skb)
 818{
 819	struct net *net;
 820
 821	net = dev_net(skb_dst(skb)->dev);
 822	if (!net->ipv4.sysctl_icmp_echo_ignore_all) {
 823		struct icmp_bxm icmp_param;
 824
 825		icmp_param.data.icmph	   = *icmp_hdr(skb);
 826		icmp_param.data.icmph.type = ICMP_ECHOREPLY;
 827		icmp_param.skb		   = skb;
 828		icmp_param.offset	   = 0;
 829		icmp_param.data_len	   = skb->len;
 830		icmp_param.head_len	   = sizeof(struct icmphdr);
 831		icmp_reply(&icmp_param, skb);
 832	}
 
 
 833}
 834
 835/*
 836 *	Handle ICMP Timestamp requests.
 837 *	RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
 838 *		  SHOULD be in the kernel for minimum random latency.
 839 *		  MUST be accurate to a few minutes.
 840 *		  MUST be updated at least at 15Hz.
 841 */
 842static void icmp_timestamp(struct sk_buff *skb)
 843{
 844	struct timespec tv;
 845	struct icmp_bxm icmp_param;
 846	/*
 847	 *	Too short.
 848	 */
 849	if (skb->len < 4)
 850		goto out_err;
 851
 852	/*
 853	 *	Fill in the current time as ms since midnight UT:
 854	 */
 855	getnstimeofday(&tv);
 856	icmp_param.data.times[1] = htonl((tv.tv_sec % 86400) * MSEC_PER_SEC +
 857					 tv.tv_nsec / NSEC_PER_MSEC);
 858	icmp_param.data.times[2] = icmp_param.data.times[1];
 859	if (skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4))
 860		BUG();
 
 861	icmp_param.data.icmph	   = *icmp_hdr(skb);
 862	icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
 863	icmp_param.data.icmph.code = 0;
 864	icmp_param.skb		   = skb;
 865	icmp_param.offset	   = 0;
 866	icmp_param.data_len	   = 0;
 867	icmp_param.head_len	   = sizeof(struct icmphdr) + 12;
 868	icmp_reply(&icmp_param, skb);
 869out:
 870	return;
 871out_err:
 872	ICMP_INC_STATS_BH(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
 873	goto out;
 874}
 875
 876static void icmp_discard(struct sk_buff *skb)
 877{
 
 
 878}
 879
 880/*
 881 *	Deal with incoming ICMP packets.
 882 */
 883int icmp_rcv(struct sk_buff *skb)
 884{
 885	struct icmphdr *icmph;
 886	struct rtable *rt = skb_rtable(skb);
 887	struct net *net = dev_net(rt->dst.dev);
 
 888
 889	if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
 890		struct sec_path *sp = skb_sec_path(skb);
 891		int nh;
 892
 893		if (!(sp && sp->xvec[sp->len - 1]->props.flags &
 894				 XFRM_STATE_ICMP))
 895			goto drop;
 896
 897		if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr)))
 898			goto drop;
 899
 900		nh = skb_network_offset(skb);
 901		skb_set_network_header(skb, sizeof(*icmph));
 902
 903		if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb))
 904			goto drop;
 905
 906		skb_set_network_header(skb, nh);
 907	}
 908
 909	ICMP_INC_STATS_BH(net, ICMP_MIB_INMSGS);
 910
 911	switch (skb->ip_summed) {
 912	case CHECKSUM_COMPLETE:
 913		if (!csum_fold(skb->csum))
 914			break;
 915		/* fall through */
 916	case CHECKSUM_NONE:
 917		skb->csum = 0;
 918		if (__skb_checksum_complete(skb))
 919			goto csum_error;
 920	}
 921
 922	if (!pskb_pull(skb, sizeof(*icmph)))
 923		goto error;
 924
 925	icmph = icmp_hdr(skb);
 926
 927	ICMPMSGIN_INC_STATS_BH(net, icmph->type);
 928	/*
 929	 *	18 is the highest 'known' ICMP type. Anything else is a mystery
 930	 *
 931	 *	RFC 1122: 3.2.2  Unknown ICMP messages types MUST be silently
 932	 *		  discarded.
 933	 */
 934	if (icmph->type > NR_ICMP_TYPES)
 935		goto error;
 936
 937
 938	/*
 939	 *	Parse the ICMP message
 940	 */
 941
 942	if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
 943		/*
 944		 *	RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
 945		 *	  silently ignored (we let user decide with a sysctl).
 946		 *	RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
 947		 *	  discarded if to broadcast/multicast.
 948		 */
 949		if ((icmph->type == ICMP_ECHO ||
 950		     icmph->type == ICMP_TIMESTAMP) &&
 951		    net->ipv4.sysctl_icmp_echo_ignore_broadcasts) {
 952			goto error;
 953		}
 954		if (icmph->type != ICMP_ECHO &&
 955		    icmph->type != ICMP_TIMESTAMP &&
 956		    icmph->type != ICMP_ADDRESS &&
 957		    icmph->type != ICMP_ADDRESSREPLY) {
 958			goto error;
 959		}
 960	}
 961
 962	icmp_pointers[icmph->type].handler(skb);
 
 
 
 
 
 963
 964drop:
 965	kfree_skb(skb);
 966	return 0;
 967csum_error:
 968	ICMP_INC_STATS_BH(net, ICMP_MIB_CSUMERRORS);
 969error:
 970	ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
 971	goto drop;
 972}
 973
 974void icmp_err(struct sk_buff *skb, u32 info)
 975{
 976	struct iphdr *iph = (struct iphdr *)skb->data;
 977	int offset = iph->ihl<<2;
 978	struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset);
 979	int type = icmp_hdr(skb)->type;
 980	int code = icmp_hdr(skb)->code;
 981	struct net *net = dev_net(skb->dev);
 982
 983	/*
 984	 * Use ping_err to handle all icmp errors except those
 985	 * triggered by ICMP_ECHOREPLY which sent from kernel.
 986	 */
 987	if (icmph->type != ICMP_ECHOREPLY) {
 988		ping_err(skb, offset, info);
 989		return;
 990	}
 991
 992	if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
 993		ipv4_update_pmtu(skb, net, info, 0, 0, IPPROTO_ICMP, 0);
 994	else if (type == ICMP_REDIRECT)
 995		ipv4_redirect(skb, net, 0, 0, IPPROTO_ICMP, 0);
 996}
 997
 998/*
 999 *	This table is the definition of how we handle ICMP.
1000 */
1001static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
1002	[ICMP_ECHOREPLY] = {
1003		.handler = ping_rcv,
1004	},
1005	[1] = {
1006		.handler = icmp_discard,
1007		.error = 1,
1008	},
1009	[2] = {
1010		.handler = icmp_discard,
1011		.error = 1,
1012	},
1013	[ICMP_DEST_UNREACH] = {
1014		.handler = icmp_unreach,
1015		.error = 1,
1016	},
1017	[ICMP_SOURCE_QUENCH] = {
1018		.handler = icmp_unreach,
1019		.error = 1,
1020	},
1021	[ICMP_REDIRECT] = {
1022		.handler = icmp_redirect,
1023		.error = 1,
1024	},
1025	[6] = {
1026		.handler = icmp_discard,
1027		.error = 1,
1028	},
1029	[7] = {
1030		.handler = icmp_discard,
1031		.error = 1,
1032	},
1033	[ICMP_ECHO] = {
1034		.handler = icmp_echo,
1035	},
1036	[9] = {
1037		.handler = icmp_discard,
1038		.error = 1,
1039	},
1040	[10] = {
1041		.handler = icmp_discard,
1042		.error = 1,
1043	},
1044	[ICMP_TIME_EXCEEDED] = {
1045		.handler = icmp_unreach,
1046		.error = 1,
1047	},
1048	[ICMP_PARAMETERPROB] = {
1049		.handler = icmp_unreach,
1050		.error = 1,
1051	},
1052	[ICMP_TIMESTAMP] = {
1053		.handler = icmp_timestamp,
1054	},
1055	[ICMP_TIMESTAMPREPLY] = {
1056		.handler = icmp_discard,
1057	},
1058	[ICMP_INFO_REQUEST] = {
1059		.handler = icmp_discard,
1060	},
1061	[ICMP_INFO_REPLY] = {
1062		.handler = icmp_discard,
1063	},
1064	[ICMP_ADDRESS] = {
1065		.handler = icmp_discard,
1066	},
1067	[ICMP_ADDRESSREPLY] = {
1068		.handler = icmp_discard,
1069	},
1070};
1071
1072static void __net_exit icmp_sk_exit(struct net *net)
1073{
1074	int i;
1075
1076	for_each_possible_cpu(i)
1077		inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]);
1078	kfree(net->ipv4.icmp_sk);
1079	net->ipv4.icmp_sk = NULL;
1080}
1081
1082static int __net_init icmp_sk_init(struct net *net)
1083{
1084	int i, err;
1085
1086	net->ipv4.icmp_sk =
1087		kzalloc(nr_cpu_ids * sizeof(struct sock *), GFP_KERNEL);
1088	if (net->ipv4.icmp_sk == NULL)
1089		return -ENOMEM;
1090
1091	for_each_possible_cpu(i) {
1092		struct sock *sk;
1093
1094		err = inet_ctl_sock_create(&sk, PF_INET,
1095					   SOCK_RAW, IPPROTO_ICMP, net);
1096		if (err < 0)
1097			goto fail;
1098
1099		net->ipv4.icmp_sk[i] = sk;
1100
1101		/* Enough space for 2 64K ICMP packets, including
1102		 * sk_buff/skb_shared_info struct overhead.
1103		 */
1104		sk->sk_sndbuf =	2 * SKB_TRUESIZE(64 * 1024);
1105
1106		/*
1107		 * Speedup sock_wfree()
1108		 */
1109		sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1110		inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT;
1111	}
1112
1113	/* Control parameters for ECHO replies. */
1114	net->ipv4.sysctl_icmp_echo_ignore_all = 0;
1115	net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1;
1116
1117	/* Control parameter - ignore bogus broadcast responses? */
1118	net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1;
1119
1120	/*
1121	 * 	Configurable global rate limit.
1122	 *
1123	 *	ratelimit defines tokens/packet consumed for dst->rate_token
1124	 *	bucket ratemask defines which icmp types are ratelimited by
1125	 *	setting	it's bit position.
1126	 *
1127	 *	default:
1128	 *	dest unreachable (3), source quench (4),
1129	 *	time exceeded (11), parameter problem (12)
1130	 */
1131
1132	net->ipv4.sysctl_icmp_ratelimit = 1 * HZ;
1133	net->ipv4.sysctl_icmp_ratemask = 0x1818;
1134	net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0;
1135
1136	return 0;
1137
1138fail:
1139	for_each_possible_cpu(i)
1140		inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]);
1141	kfree(net->ipv4.icmp_sk);
1142	return err;
1143}
1144
1145static struct pernet_operations __net_initdata icmp_sk_ops = {
1146       .init = icmp_sk_init,
1147       .exit = icmp_sk_exit,
1148};
1149
1150int __init icmp_init(void)
1151{
1152	return register_pernet_subsys(&icmp_sk_ops);
1153}
v4.17
   1/*
   2 *	NET3:	Implementation of the ICMP protocol layer.
   3 *
   4 *		Alan Cox, <alan@lxorguk.ukuu.org.uk>
   5 *
   6 *	This program is free software; you can redistribute it and/or
   7 *	modify it under the terms of the GNU General Public License
   8 *	as published by the Free Software Foundation; either version
   9 *	2 of the License, or (at your option) any later version.
  10 *
  11 *	Some of the function names and the icmp unreach table for this
  12 *	module were derived from [icmp.c 1.0.11 06/02/93] by
  13 *	Ross Biro, Fred N. van Kempen, Mark Evans, Alan Cox, Gerhard Koerting.
  14 *	Other than that this module is a complete rewrite.
  15 *
  16 *	Fixes:
  17 *	Clemens Fruhwirth	:	introduce global icmp rate limiting
  18 *					with icmp type masking ability instead
  19 *					of broken per type icmp timeouts.
  20 *		Mike Shaver	:	RFC1122 checks.
  21 *		Alan Cox	:	Multicast ping reply as self.
  22 *		Alan Cox	:	Fix atomicity lockup in ip_build_xmit
  23 *					call.
  24 *		Alan Cox	:	Added 216,128 byte paths to the MTU
  25 *					code.
  26 *		Martin Mares	:	RFC1812 checks.
  27 *		Martin Mares	:	Can be configured to follow redirects
  28 *					if acting as a router _without_ a
  29 *					routing protocol (RFC 1812).
  30 *		Martin Mares	:	Echo requests may be configured to
  31 *					be ignored (RFC 1812).
  32 *		Martin Mares	:	Limitation of ICMP error message
  33 *					transmit rate (RFC 1812).
  34 *		Martin Mares	:	TOS and Precedence set correctly
  35 *					(RFC 1812).
  36 *		Martin Mares	:	Now copying as much data from the
  37 *					original packet as we can without
  38 *					exceeding 576 bytes (RFC 1812).
  39 *	Willy Konynenberg	:	Transparent proxying support.
  40 *		Keith Owens	:	RFC1191 correction for 4.2BSD based
  41 *					path MTU bug.
  42 *		Thomas Quinot	:	ICMP Dest Unreach codes up to 15 are
  43 *					valid (RFC 1812).
  44 *		Andi Kleen	:	Check all packet lengths properly
  45 *					and moved all kfree_skb() up to
  46 *					icmp_rcv.
  47 *		Andi Kleen	:	Move the rate limit bookkeeping
  48 *					into the dest entry and use a token
  49 *					bucket filter (thanks to ANK). Make
  50 *					the rates sysctl configurable.
  51 *		Yu Tianli	:	Fixed two ugly bugs in icmp_send
  52 *					- IP option length was accounted wrongly
  53 *					- ICMP header length was not accounted
  54 *					  at all.
  55 *              Tristan Greaves :       Added sysctl option to ignore bogus
  56 *              			broadcast responses from broken routers.
  57 *
  58 * To Fix:
  59 *
  60 *	- Should use skb_pull() instead of all the manual checking.
  61 *	  This would also greatly simply some upper layer error handlers. --AK
  62 *
  63 */
  64
  65#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  66
  67#include <linux/module.h>
  68#include <linux/types.h>
  69#include <linux/jiffies.h>
  70#include <linux/kernel.h>
  71#include <linux/fcntl.h>
  72#include <linux/socket.h>
  73#include <linux/in.h>
  74#include <linux/inet.h>
  75#include <linux/inetdevice.h>
  76#include <linux/netdevice.h>
  77#include <linux/string.h>
  78#include <linux/netfilter_ipv4.h>
  79#include <linux/slab.h>
  80#include <net/snmp.h>
  81#include <net/ip.h>
  82#include <net/route.h>
  83#include <net/protocol.h>
  84#include <net/icmp.h>
  85#include <net/tcp.h>
  86#include <net/udp.h>
  87#include <net/raw.h>
  88#include <net/ping.h>
  89#include <linux/skbuff.h>
  90#include <net/sock.h>
  91#include <linux/errno.h>
  92#include <linux/timer.h>
  93#include <linux/init.h>
  94#include <linux/uaccess.h>
  95#include <net/checksum.h>
  96#include <net/xfrm.h>
  97#include <net/inet_common.h>
  98#include <net/ip_fib.h>
  99#include <net/l3mdev.h>
 100
 101/*
 102 *	Build xmit assembly blocks
 103 */
 104
 105struct icmp_bxm {
 106	struct sk_buff *skb;
 107	int offset;
 108	int data_len;
 109
 110	struct {
 111		struct icmphdr icmph;
 112		__be32	       times[3];
 113	} data;
 114	int head_len;
 115	struct ip_options_data replyopts;
 116};
 117
 118/* An array of errno for error messages from dest unreach. */
 119/* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */
 120
 121const struct icmp_err icmp_err_convert[] = {
 122	{
 123		.errno = ENETUNREACH,	/* ICMP_NET_UNREACH */
 124		.fatal = 0,
 125	},
 126	{
 127		.errno = EHOSTUNREACH,	/* ICMP_HOST_UNREACH */
 128		.fatal = 0,
 129	},
 130	{
 131		.errno = ENOPROTOOPT	/* ICMP_PROT_UNREACH */,
 132		.fatal = 1,
 133	},
 134	{
 135		.errno = ECONNREFUSED,	/* ICMP_PORT_UNREACH */
 136		.fatal = 1,
 137	},
 138	{
 139		.errno = EMSGSIZE,	/* ICMP_FRAG_NEEDED */
 140		.fatal = 0,
 141	},
 142	{
 143		.errno = EOPNOTSUPP,	/* ICMP_SR_FAILED */
 144		.fatal = 0,
 145	},
 146	{
 147		.errno = ENETUNREACH,	/* ICMP_NET_UNKNOWN */
 148		.fatal = 1,
 149	},
 150	{
 151		.errno = EHOSTDOWN,	/* ICMP_HOST_UNKNOWN */
 152		.fatal = 1,
 153	},
 154	{
 155		.errno = ENONET,	/* ICMP_HOST_ISOLATED */
 156		.fatal = 1,
 157	},
 158	{
 159		.errno = ENETUNREACH,	/* ICMP_NET_ANO	*/
 160		.fatal = 1,
 161	},
 162	{
 163		.errno = EHOSTUNREACH,	/* ICMP_HOST_ANO */
 164		.fatal = 1,
 165	},
 166	{
 167		.errno = ENETUNREACH,	/* ICMP_NET_UNR_TOS */
 168		.fatal = 0,
 169	},
 170	{
 171		.errno = EHOSTUNREACH,	/* ICMP_HOST_UNR_TOS */
 172		.fatal = 0,
 173	},
 174	{
 175		.errno = EHOSTUNREACH,	/* ICMP_PKT_FILTERED */
 176		.fatal = 1,
 177	},
 178	{
 179		.errno = EHOSTUNREACH,	/* ICMP_PREC_VIOLATION */
 180		.fatal = 1,
 181	},
 182	{
 183		.errno = EHOSTUNREACH,	/* ICMP_PREC_CUTOFF */
 184		.fatal = 1,
 185	},
 186};
 187EXPORT_SYMBOL(icmp_err_convert);
 188
 189/*
 190 *	ICMP control array. This specifies what to do with each ICMP.
 191 */
 192
 193struct icmp_control {
 194	bool (*handler)(struct sk_buff *skb);
 195	short   error;		/* This ICMP is classed as an error message */
 196};
 197
 198static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1];
 199
 200/*
 201 *	The ICMP socket(s). This is the most convenient way to flow control
 202 *	our ICMP output as well as maintain a clean interface throughout
 203 *	all layers. All Socketless IP sends will soon be gone.
 204 *
 205 *	On SMP we have one ICMP socket per-cpu.
 206 */
 207static struct sock *icmp_sk(struct net *net)
 208{
 209	return *this_cpu_ptr(net->ipv4.icmp_sk);
 210}
 211
 212/* Called with BH disabled */
 213static inline struct sock *icmp_xmit_lock(struct net *net)
 214{
 215	struct sock *sk;
 216
 
 
 217	sk = icmp_sk(net);
 218
 219	if (unlikely(!spin_trylock(&sk->sk_lock.slock))) {
 220		/* This can happen if the output path signals a
 221		 * dst_link_failure() for an outgoing ICMP packet.
 222		 */
 
 223		return NULL;
 224	}
 225	return sk;
 226}
 227
 228static inline void icmp_xmit_unlock(struct sock *sk)
 229{
 230	spin_unlock(&sk->sk_lock.slock);
 231}
 232
 233int sysctl_icmp_msgs_per_sec __read_mostly = 1000;
 234int sysctl_icmp_msgs_burst __read_mostly = 50;
 235
 236static struct {
 237	spinlock_t	lock;
 238	u32		credit;
 239	u32		stamp;
 240} icmp_global = {
 241	.lock		= __SPIN_LOCK_UNLOCKED(icmp_global.lock),
 242};
 243
 244/**
 245 * icmp_global_allow - Are we allowed to send one more ICMP message ?
 246 *
 247 * Uses a token bucket to limit our ICMP messages to sysctl_icmp_msgs_per_sec.
 248 * Returns false if we reached the limit and can not send another packet.
 249 * Note: called with BH disabled
 250 */
 251bool icmp_global_allow(void)
 252{
 253	u32 credit, delta, incr = 0, now = (u32)jiffies;
 254	bool rc = false;
 255
 256	/* Check if token bucket is empty and cannot be refilled
 257	 * without taking the spinlock.
 258	 */
 259	if (!icmp_global.credit) {
 260		delta = min_t(u32, now - icmp_global.stamp, HZ);
 261		if (delta < HZ / 50)
 262			return false;
 263	}
 264
 265	spin_lock(&icmp_global.lock);
 266	delta = min_t(u32, now - icmp_global.stamp, HZ);
 267	if (delta >= HZ / 50) {
 268		incr = sysctl_icmp_msgs_per_sec * delta / HZ ;
 269		if (incr)
 270			icmp_global.stamp = now;
 271	}
 272	credit = min_t(u32, icmp_global.credit + incr, sysctl_icmp_msgs_burst);
 273	if (credit) {
 274		credit--;
 275		rc = true;
 276	}
 277	icmp_global.credit = credit;
 278	spin_unlock(&icmp_global.lock);
 279	return rc;
 280}
 281EXPORT_SYMBOL(icmp_global_allow);
 282
 283static bool icmpv4_mask_allow(struct net *net, int type, int code)
 284{
 285	if (type > NR_ICMP_TYPES)
 286		return true;
 287
 288	/* Don't limit PMTU discovery. */
 289	if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
 290		return true;
 291
 292	/* Limit if icmp type is enabled in ratemask. */
 293	if (!((1 << type) & net->ipv4.sysctl_icmp_ratemask))
 294		return true;
 295
 296	return false;
 297}
 298
 299static bool icmpv4_global_allow(struct net *net, int type, int code)
 300{
 301	if (icmpv4_mask_allow(net, type, code))
 302		return true;
 303
 304	if (icmp_global_allow())
 305		return true;
 306
 307	return false;
 308}
 309
 310/*
 311 *	Send an ICMP frame.
 312 */
 313
 314static bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt,
 315			       struct flowi4 *fl4, int type, int code)
 316{
 317	struct dst_entry *dst = &rt->dst;
 318	struct inet_peer *peer;
 319	bool rc = true;
 320	int vif;
 321
 322	if (icmpv4_mask_allow(net, type, code))
 
 
 
 
 323		goto out;
 324
 325	/* No rate limit on loopback */
 326	if (dst->dev && (dst->dev->flags&IFF_LOOPBACK))
 327		goto out;
 328
 329	vif = l3mdev_master_ifindex(dst->dev);
 330	peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, vif, 1);
 331	rc = inet_peer_xrlim_allow(peer, net->ipv4.sysctl_icmp_ratelimit);
 332	if (peer)
 333		inet_putpeer(peer);
 
 
 
 334out:
 335	return rc;
 336}
 337
 338/*
 339 *	Maintain the counters used in the SNMP statistics for outgoing ICMP
 340 */
 341void icmp_out_count(struct net *net, unsigned char type)
 342{
 343	ICMPMSGOUT_INC_STATS(net, type);
 344	ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS);
 345}
 346
 347/*
 348 *	Checksum each fragment, and on the first include the headers and final
 349 *	checksum.
 350 */
 351static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd,
 352			  struct sk_buff *skb)
 353{
 354	struct icmp_bxm *icmp_param = (struct icmp_bxm *)from;
 355	__wsum csum;
 356
 357	csum = skb_copy_and_csum_bits(icmp_param->skb,
 358				      icmp_param->offset + offset,
 359				      to, len, 0);
 360
 361	skb->csum = csum_block_add(skb->csum, csum, odd);
 362	if (icmp_pointers[icmp_param->data.icmph.type].error)
 363		nf_ct_attach(skb, icmp_param->skb);
 364	return 0;
 365}
 366
 367static void icmp_push_reply(struct icmp_bxm *icmp_param,
 368			    struct flowi4 *fl4,
 369			    struct ipcm_cookie *ipc, struct rtable **rt)
 370{
 371	struct sock *sk;
 372	struct sk_buff *skb;
 373
 374	sk = icmp_sk(dev_net((*rt)->dst.dev));
 375	if (ip_append_data(sk, fl4, icmp_glue_bits, icmp_param,
 376			   icmp_param->data_len+icmp_param->head_len,
 377			   icmp_param->head_len,
 378			   ipc, rt, MSG_DONTWAIT) < 0) {
 379		__ICMP_INC_STATS(sock_net(sk), ICMP_MIB_OUTERRORS);
 380		ip_flush_pending_frames(sk);
 381	} else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
 382		struct icmphdr *icmph = icmp_hdr(skb);
 383		__wsum csum = 0;
 384		struct sk_buff *skb1;
 385
 386		skb_queue_walk(&sk->sk_write_queue, skb1) {
 387			csum = csum_add(csum, skb1->csum);
 388		}
 389		csum = csum_partial_copy_nocheck((void *)&icmp_param->data,
 390						 (char *)icmph,
 391						 icmp_param->head_len, csum);
 392		icmph->checksum = csum_fold(csum);
 393		skb->ip_summed = CHECKSUM_NONE;
 394		ip_push_pending_frames(sk, fl4);
 395	}
 396}
 397
 398/*
 399 *	Driving logic for building and sending ICMP messages.
 400 */
 401
 402static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
 403{
 404	struct ipcm_cookie ipc;
 405	struct rtable *rt = skb_rtable(skb);
 406	struct net *net = dev_net(rt->dst.dev);
 407	struct flowi4 fl4;
 408	struct sock *sk;
 409	struct inet_sock *inet;
 410	__be32 daddr, saddr;
 411	u32 mark = IP4_REPLY_MARK(net, skb->mark);
 412	int type = icmp_param->data.icmph.type;
 413	int code = icmp_param->data.icmph.code;
 414
 415	if (ip_options_echo(net, &icmp_param->replyopts.opt.opt, skb))
 416		return;
 417
 418	/* Needed by both icmp_global_allow and icmp_xmit_lock */
 419	local_bh_disable();
 420
 421	/* global icmp_msgs_per_sec */
 422	if (!icmpv4_global_allow(net, type, code))
 423		goto out_bh_enable;
 424
 425	sk = icmp_xmit_lock(net);
 426	if (!sk)
 427		goto out_bh_enable;
 428	inet = inet_sk(sk);
 429
 430	icmp_param->data.icmph.checksum = 0;
 431
 432	inet->tos = ip_hdr(skb)->tos;
 433	sk->sk_mark = mark;
 434	daddr = ipc.addr = ip_hdr(skb)->saddr;
 435	saddr = fib_compute_spec_dst(skb);
 436	ipc.opt = NULL;
 437	ipc.tx_flags = 0;
 438	ipc.ttl = 0;
 439	ipc.tos = -1;
 440
 441	if (icmp_param->replyopts.opt.opt.optlen) {
 442		ipc.opt = &icmp_param->replyopts.opt;
 443		if (ipc.opt->opt.srr)
 444			daddr = icmp_param->replyopts.opt.opt.faddr;
 445	}
 446	memset(&fl4, 0, sizeof(fl4));
 447	fl4.daddr = daddr;
 448	fl4.saddr = saddr;
 449	fl4.flowi4_mark = mark;
 450	fl4.flowi4_uid = sock_net_uid(net, NULL);
 451	fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos);
 452	fl4.flowi4_proto = IPPROTO_ICMP;
 453	fl4.flowi4_oif = l3mdev_master_ifindex(skb->dev);
 454	security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
 455	rt = ip_route_output_key(net, &fl4);
 456	if (IS_ERR(rt))
 457		goto out_unlock;
 458	if (icmpv4_xrlim_allow(net, rt, &fl4, type, code))
 
 459		icmp_push_reply(icmp_param, &fl4, &ipc, &rt);
 460	ip_rt_put(rt);
 461out_unlock:
 462	icmp_xmit_unlock(sk);
 463out_bh_enable:
 464	local_bh_enable();
 465}
 466
 467static struct rtable *icmp_route_lookup(struct net *net,
 468					struct flowi4 *fl4,
 469					struct sk_buff *skb_in,
 470					const struct iphdr *iph,
 471					__be32 saddr, u8 tos, u32 mark,
 472					int type, int code,
 473					struct icmp_bxm *param)
 474{
 475	struct rtable *rt, *rt2;
 476	struct flowi4 fl4_dec;
 477	int err;
 478
 479	memset(fl4, 0, sizeof(*fl4));
 480	fl4->daddr = (param->replyopts.opt.opt.srr ?
 481		      param->replyopts.opt.opt.faddr : iph->saddr);
 482	fl4->saddr = saddr;
 483	fl4->flowi4_mark = mark;
 484	fl4->flowi4_uid = sock_net_uid(net, NULL);
 485	fl4->flowi4_tos = RT_TOS(tos);
 486	fl4->flowi4_proto = IPPROTO_ICMP;
 487	fl4->fl4_icmp_type = type;
 488	fl4->fl4_icmp_code = code;
 489	fl4->flowi4_oif = l3mdev_master_ifindex(skb_dst(skb_in)->dev);
 490
 491	security_skb_classify_flow(skb_in, flowi4_to_flowi(fl4));
 492	rt = ip_route_output_key_hash(net, fl4, skb_in);
 493	if (IS_ERR(rt))
 494		return rt;
 495
 496	/* No need to clone since we're just using its address. */
 497	rt2 = rt;
 498
 499	rt = (struct rtable *) xfrm_lookup(net, &rt->dst,
 500					   flowi4_to_flowi(fl4), NULL, 0);
 501	if (!IS_ERR(rt)) {
 502		if (rt != rt2)
 503			return rt;
 504	} else if (PTR_ERR(rt) == -EPERM) {
 505		rt = NULL;
 506	} else
 507		return rt;
 508
 509	err = xfrm_decode_session_reverse(skb_in, flowi4_to_flowi(&fl4_dec), AF_INET);
 510	if (err)
 511		goto relookup_failed;
 512
 513	if (inet_addr_type_dev_table(net, skb_dst(skb_in)->dev,
 514				     fl4_dec.saddr) == RTN_LOCAL) {
 515		rt2 = __ip_route_output_key(net, &fl4_dec);
 516		if (IS_ERR(rt2))
 517			err = PTR_ERR(rt2);
 518	} else {
 519		struct flowi4 fl4_2 = {};
 520		unsigned long orefdst;
 521
 522		fl4_2.daddr = fl4_dec.saddr;
 523		rt2 = ip_route_output_key(net, &fl4_2);
 524		if (IS_ERR(rt2)) {
 525			err = PTR_ERR(rt2);
 526			goto relookup_failed;
 527		}
 528		/* Ugh! */
 529		orefdst = skb_in->_skb_refdst; /* save old refdst */
 530		skb_dst_set(skb_in, NULL);
 531		err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr,
 532				     RT_TOS(tos), rt2->dst.dev);
 533
 534		dst_release(&rt2->dst);
 535		rt2 = skb_rtable(skb_in);
 536		skb_in->_skb_refdst = orefdst; /* restore old refdst */
 537	}
 538
 539	if (err)
 540		goto relookup_failed;
 541
 542	rt2 = (struct rtable *) xfrm_lookup(net, &rt2->dst,
 543					    flowi4_to_flowi(&fl4_dec), NULL,
 544					    XFRM_LOOKUP_ICMP);
 545	if (!IS_ERR(rt2)) {
 546		dst_release(&rt->dst);
 547		memcpy(fl4, &fl4_dec, sizeof(*fl4));
 548		rt = rt2;
 549	} else if (PTR_ERR(rt2) == -EPERM) {
 550		if (rt)
 551			dst_release(&rt->dst);
 552		return rt2;
 553	} else {
 554		err = PTR_ERR(rt2);
 555		goto relookup_failed;
 556	}
 557	return rt;
 558
 559relookup_failed:
 560	if (rt)
 561		return rt;
 562	return ERR_PTR(err);
 563}
 564
 565/*
 566 *	Send an ICMP message in response to a situation
 567 *
 568 *	RFC 1122: 3.2.2	MUST send at least the IP header and 8 bytes of header.
 569 *		  MAY send more (we do).
 570 *			MUST NOT change this header information.
 571 *			MUST NOT reply to a multicast/broadcast IP address.
 572 *			MUST NOT reply to a multicast/broadcast MAC address.
 573 *			MUST reply to only the first fragment.
 574 */
 575
 576void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
 577{
 578	struct iphdr *iph;
 579	int room;
 580	struct icmp_bxm icmp_param;
 581	struct rtable *rt = skb_rtable(skb_in);
 582	struct ipcm_cookie ipc;
 583	struct flowi4 fl4;
 584	__be32 saddr;
 585	u8  tos;
 586	u32 mark;
 587	struct net *net;
 588	struct sock *sk;
 589
 590	if (!rt)
 591		goto out;
 592	net = dev_net(rt->dst.dev);
 593
 594	/*
 595	 *	Find the original header. It is expected to be valid, of course.
 596	 *	Check this, icmp_send is called from the most obscure devices
 597	 *	sometimes.
 598	 */
 599	iph = ip_hdr(skb_in);
 600
 601	if ((u8 *)iph < skb_in->head ||
 602	    (skb_network_header(skb_in) + sizeof(*iph)) >
 603	    skb_tail_pointer(skb_in))
 604		goto out;
 605
 606	/*
 607	 *	No replies to physical multicast/broadcast
 608	 */
 609	if (skb_in->pkt_type != PACKET_HOST)
 610		goto out;
 611
 612	/*
 613	 *	Now check at the protocol level
 614	 */
 615	if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
 616		goto out;
 617
 618	/*
 619	 *	Only reply to fragment 0. We byte re-order the constant
 620	 *	mask for efficiency.
 621	 */
 622	if (iph->frag_off & htons(IP_OFFSET))
 623		goto out;
 624
 625	/*
 626	 *	If we send an ICMP error to an ICMP error a mess would result..
 627	 */
 628	if (icmp_pointers[type].error) {
 629		/*
 630		 *	We are an error, check if we are replying to an
 631		 *	ICMP error
 632		 */
 633		if (iph->protocol == IPPROTO_ICMP) {
 634			u8 _inner_type, *itp;
 635
 636			itp = skb_header_pointer(skb_in,
 637						 skb_network_header(skb_in) +
 638						 (iph->ihl << 2) +
 639						 offsetof(struct icmphdr,
 640							  type) -
 641						 skb_in->data,
 642						 sizeof(_inner_type),
 643						 &_inner_type);
 644			if (!itp)
 645				goto out;
 646
 647			/*
 648			 *	Assume any unknown ICMP type is an error. This
 649			 *	isn't specified by the RFC, but think about it..
 650			 */
 651			if (*itp > NR_ICMP_TYPES ||
 652			    icmp_pointers[*itp].error)
 653				goto out;
 654		}
 655	}
 656
 657	/* Needed by both icmp_global_allow and icmp_xmit_lock */
 658	local_bh_disable();
 659
 660	/* Check global sysctl_icmp_msgs_per_sec ratelimit, unless
 661	 * incoming dev is loopback.  If outgoing dev change to not be
 662	 * loopback, then peer ratelimit still work (in icmpv4_xrlim_allow)
 663	 */
 664	if (!(skb_in->dev && (skb_in->dev->flags&IFF_LOOPBACK)) &&
 665	      !icmpv4_global_allow(net, type, code))
 666		goto out_bh_enable;
 667
 668	sk = icmp_xmit_lock(net);
 669	if (!sk)
 670		goto out_bh_enable;
 671
 672	/*
 673	 *	Construct source address and options.
 674	 */
 675
 676	saddr = iph->daddr;
 677	if (!(rt->rt_flags & RTCF_LOCAL)) {
 678		struct net_device *dev = NULL;
 679
 680		rcu_read_lock();
 681		if (rt_is_input_route(rt) &&
 682		    net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)
 683			dev = dev_get_by_index_rcu(net, inet_iif(skb_in));
 684
 685		if (dev)
 686			saddr = inet_select_addr(dev, 0, RT_SCOPE_LINK);
 687		else
 688			saddr = 0;
 689		rcu_read_unlock();
 690	}
 691
 692	tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) |
 693					   IPTOS_PREC_INTERNETCONTROL) :
 694					  iph->tos;
 695	mark = IP4_REPLY_MARK(net, skb_in->mark);
 696
 697	if (ip_options_echo(net, &icmp_param.replyopts.opt.opt, skb_in))
 698		goto out_unlock;
 699
 700
 701	/*
 702	 *	Prepare data for ICMP header.
 703	 */
 704
 705	icmp_param.data.icmph.type	 = type;
 706	icmp_param.data.icmph.code	 = code;
 707	icmp_param.data.icmph.un.gateway = info;
 708	icmp_param.data.icmph.checksum	 = 0;
 709	icmp_param.skb	  = skb_in;
 710	icmp_param.offset = skb_network_offset(skb_in);
 711	inet_sk(sk)->tos = tos;
 712	sk->sk_mark = mark;
 713	ipc.addr = iph->saddr;
 714	ipc.opt = &icmp_param.replyopts.opt;
 715	ipc.tx_flags = 0;
 716	ipc.ttl = 0;
 717	ipc.tos = -1;
 718
 719	rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos, mark,
 720			       type, code, &icmp_param);
 721	if (IS_ERR(rt))
 722		goto out_unlock;
 723
 724	/* peer icmp_ratelimit */
 725	if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code))
 726		goto ende;
 727
 728	/* RFC says return as much as we can without exceeding 576 bytes. */
 729
 730	room = dst_mtu(&rt->dst);
 731	if (room > 576)
 732		room = 576;
 733	room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen;
 734	room -= sizeof(struct icmphdr);
 735
 736	icmp_param.data_len = skb_in->len - icmp_param.offset;
 737	if (icmp_param.data_len > room)
 738		icmp_param.data_len = room;
 739	icmp_param.head_len = sizeof(struct icmphdr);
 740
 741	icmp_push_reply(&icmp_param, &fl4, &ipc, &rt);
 742ende:
 743	ip_rt_put(rt);
 744out_unlock:
 745	icmp_xmit_unlock(sk);
 746out_bh_enable:
 747	local_bh_enable();
 748out:;
 749}
 750EXPORT_SYMBOL(icmp_send);
 751
 752
 753static void icmp_socket_deliver(struct sk_buff *skb, u32 info)
 754{
 755	const struct iphdr *iph = (const struct iphdr *) skb->data;
 756	const struct net_protocol *ipprot;
 757	int protocol = iph->protocol;
 758
 759	/* Checkin full IP header plus 8 bytes of protocol to
 760	 * avoid additional coding at protocol handlers.
 761	 */
 762	if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) {
 763		__ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
 764		return;
 765	}
 766
 767	raw_icmp_error(skb, protocol, info);
 768
 
 769	ipprot = rcu_dereference(inet_protos[protocol]);
 770	if (ipprot && ipprot->err_handler)
 771		ipprot->err_handler(skb, info);
 
 772}
 773
 774static bool icmp_tag_validation(int proto)
 775{
 776	bool ok;
 777
 778	rcu_read_lock();
 779	ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation;
 780	rcu_read_unlock();
 781	return ok;
 782}
 783
 784/*
 785 *	Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEEDED, ICMP_QUENCH, and
 786 *	ICMP_PARAMETERPROB.
 787 */
 788
 789static bool icmp_unreach(struct sk_buff *skb)
 790{
 791	const struct iphdr *iph;
 792	struct icmphdr *icmph;
 793	struct net *net;
 794	u32 info = 0;
 795
 796	net = dev_net(skb_dst(skb)->dev);
 797
 798	/*
 799	 *	Incomplete header ?
 800	 * 	Only checks for the IP header, there should be an
 801	 *	additional check for longer headers in upper levels.
 802	 */
 803
 804	if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 805		goto out_err;
 806
 807	icmph = icmp_hdr(skb);
 808	iph   = (const struct iphdr *)skb->data;
 809
 810	if (iph->ihl < 5) /* Mangled header, drop. */
 811		goto out_err;
 812
 813	switch (icmph->type) {
 814	case ICMP_DEST_UNREACH:
 815		switch (icmph->code & 15) {
 816		case ICMP_NET_UNREACH:
 817		case ICMP_HOST_UNREACH:
 818		case ICMP_PROT_UNREACH:
 819		case ICMP_PORT_UNREACH:
 820			break;
 821		case ICMP_FRAG_NEEDED:
 822			/* for documentation of the ip_no_pmtu_disc
 823			 * values please see
 824			 * Documentation/networking/ip-sysctl.txt
 825			 */
 826			switch (net->ipv4.sysctl_ip_no_pmtu_disc) {
 827			default:
 828				net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n",
 829						    &iph->daddr);
 830				break;
 831			case 2:
 832				goto out;
 833			case 3:
 834				if (!icmp_tag_validation(iph->protocol))
 835					goto out;
 836				/* fall through */
 837			case 0:
 838				info = ntohs(icmph->un.frag.mtu);
 
 
 839			}
 840			break;
 841		case ICMP_SR_FAILED:
 842			net_dbg_ratelimited("%pI4: Source Route Failed\n",
 843					    &iph->daddr);
 844			break;
 845		default:
 846			break;
 847		}
 848		if (icmph->code > NR_ICMP_UNREACH)
 849			goto out;
 850		break;
 851	case ICMP_PARAMETERPROB:
 852		info = ntohl(icmph->un.gateway) >> 24;
 853		break;
 854	case ICMP_TIME_EXCEEDED:
 855		__ICMP_INC_STATS(net, ICMP_MIB_INTIMEEXCDS);
 856		if (icmph->code == ICMP_EXC_FRAGTIME)
 857			goto out;
 858		break;
 859	}
 860
 861	/*
 862	 *	Throw it at our lower layers
 863	 *
 864	 *	RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
 865	 *		  header.
 866	 *	RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
 867	 *		  transport layer.
 868	 *	RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
 869	 *		  transport layer.
 870	 */
 871
 872	/*
 873	 *	Check the other end isn't violating RFC 1122. Some routers send
 874	 *	bogus responses to broadcast frames. If you see this message
 875	 *	first check your netmask matches at both ends, if it does then
 876	 *	get the other vendor to fix their kit.
 877	 */
 878
 879	if (!net->ipv4.sysctl_icmp_ignore_bogus_error_responses &&
 880	    inet_addr_type_dev_table(net, skb->dev, iph->daddr) == RTN_BROADCAST) {
 881		net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n",
 882				     &ip_hdr(skb)->saddr,
 883				     icmph->type, icmph->code,
 884				     &iph->daddr, skb->dev->name);
 885		goto out;
 886	}
 887
 888	icmp_socket_deliver(skb, info);
 889
 890out:
 891	return true;
 892out_err:
 893	__ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
 894	return false;
 895}
 896
 897
 898/*
 899 *	Handle ICMP_REDIRECT.
 900 */
 901
 902static bool icmp_redirect(struct sk_buff *skb)
 903{
 904	if (skb->len < sizeof(struct iphdr)) {
 905		__ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
 906		return false;
 907	}
 908
 909	if (!pskb_may_pull(skb, sizeof(struct iphdr))) {
 910		/* there aught to be a stat */
 911		return false;
 912	}
 913
 914	icmp_socket_deliver(skb, icmp_hdr(skb)->un.gateway);
 915	return true;
 916}
 917
 918/*
 919 *	Handle ICMP_ECHO ("ping") requests.
 920 *
 921 *	RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
 922 *		  requests.
 923 *	RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
 924 *		  included in the reply.
 925 *	RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
 926 *		  echo requests, MUST have default=NOT.
 927 *	See also WRT handling of options once they are done and working.
 928 */
 929
 930static bool icmp_echo(struct sk_buff *skb)
 931{
 932	struct net *net;
 933
 934	net = dev_net(skb_dst(skb)->dev);
 935	if (!net->ipv4.sysctl_icmp_echo_ignore_all) {
 936		struct icmp_bxm icmp_param;
 937
 938		icmp_param.data.icmph	   = *icmp_hdr(skb);
 939		icmp_param.data.icmph.type = ICMP_ECHOREPLY;
 940		icmp_param.skb		   = skb;
 941		icmp_param.offset	   = 0;
 942		icmp_param.data_len	   = skb->len;
 943		icmp_param.head_len	   = sizeof(struct icmphdr);
 944		icmp_reply(&icmp_param, skb);
 945	}
 946	/* should there be an ICMP stat for ignored echos? */
 947	return true;
 948}
 949
 950/*
 951 *	Handle ICMP Timestamp requests.
 952 *	RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
 953 *		  SHOULD be in the kernel for minimum random latency.
 954 *		  MUST be accurate to a few minutes.
 955 *		  MUST be updated at least at 15Hz.
 956 */
 957static bool icmp_timestamp(struct sk_buff *skb)
 958{
 
 959	struct icmp_bxm icmp_param;
 960	/*
 961	 *	Too short.
 962	 */
 963	if (skb->len < 4)
 964		goto out_err;
 965
 966	/*
 967	 *	Fill in the current time as ms since midnight UT:
 968	 */
 969	icmp_param.data.times[1] = inet_current_timestamp();
 
 
 970	icmp_param.data.times[2] = icmp_param.data.times[1];
 971
 972	BUG_ON(skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4));
 973
 974	icmp_param.data.icmph	   = *icmp_hdr(skb);
 975	icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
 976	icmp_param.data.icmph.code = 0;
 977	icmp_param.skb		   = skb;
 978	icmp_param.offset	   = 0;
 979	icmp_param.data_len	   = 0;
 980	icmp_param.head_len	   = sizeof(struct icmphdr) + 12;
 981	icmp_reply(&icmp_param, skb);
 982	return true;
 983
 984out_err:
 985	__ICMP_INC_STATS(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
 986	return false;
 987}
 988
 989static bool icmp_discard(struct sk_buff *skb)
 990{
 991	/* pretend it was a success */
 992	return true;
 993}
 994
 995/*
 996 *	Deal with incoming ICMP packets.
 997 */
 998int icmp_rcv(struct sk_buff *skb)
 999{
1000	struct icmphdr *icmph;
1001	struct rtable *rt = skb_rtable(skb);
1002	struct net *net = dev_net(rt->dst.dev);
1003	bool success;
1004
1005	if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
1006		struct sec_path *sp = skb_sec_path(skb);
1007		int nh;
1008
1009		if (!(sp && sp->xvec[sp->len - 1]->props.flags &
1010				 XFRM_STATE_ICMP))
1011			goto drop;
1012
1013		if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr)))
1014			goto drop;
1015
1016		nh = skb_network_offset(skb);
1017		skb_set_network_header(skb, sizeof(*icmph));
1018
1019		if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb))
1020			goto drop;
1021
1022		skb_set_network_header(skb, nh);
1023	}
1024
1025	__ICMP_INC_STATS(net, ICMP_MIB_INMSGS);
1026
1027	if (skb_checksum_simple_validate(skb))
1028		goto csum_error;
 
 
 
 
 
 
 
 
1029
1030	if (!pskb_pull(skb, sizeof(*icmph)))
1031		goto error;
1032
1033	icmph = icmp_hdr(skb);
1034
1035	ICMPMSGIN_INC_STATS(net, icmph->type);
1036	/*
1037	 *	18 is the highest 'known' ICMP type. Anything else is a mystery
1038	 *
1039	 *	RFC 1122: 3.2.2  Unknown ICMP messages types MUST be silently
1040	 *		  discarded.
1041	 */
1042	if (icmph->type > NR_ICMP_TYPES)
1043		goto error;
1044
1045
1046	/*
1047	 *	Parse the ICMP message
1048	 */
1049
1050	if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
1051		/*
1052		 *	RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
1053		 *	  silently ignored (we let user decide with a sysctl).
1054		 *	RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
1055		 *	  discarded if to broadcast/multicast.
1056		 */
1057		if ((icmph->type == ICMP_ECHO ||
1058		     icmph->type == ICMP_TIMESTAMP) &&
1059		    net->ipv4.sysctl_icmp_echo_ignore_broadcasts) {
1060			goto error;
1061		}
1062		if (icmph->type != ICMP_ECHO &&
1063		    icmph->type != ICMP_TIMESTAMP &&
1064		    icmph->type != ICMP_ADDRESS &&
1065		    icmph->type != ICMP_ADDRESSREPLY) {
1066			goto error;
1067		}
1068	}
1069
1070	success = icmp_pointers[icmph->type].handler(skb);
1071
1072	if (success)  {
1073		consume_skb(skb);
1074		return NET_RX_SUCCESS;
1075	}
1076
1077drop:
1078	kfree_skb(skb);
1079	return NET_RX_DROP;
1080csum_error:
1081	__ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS);
1082error:
1083	__ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
1084	goto drop;
1085}
1086
1087void icmp_err(struct sk_buff *skb, u32 info)
1088{
1089	struct iphdr *iph = (struct iphdr *)skb->data;
1090	int offset = iph->ihl<<2;
1091	struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset);
1092	int type = icmp_hdr(skb)->type;
1093	int code = icmp_hdr(skb)->code;
1094	struct net *net = dev_net(skb->dev);
1095
1096	/*
1097	 * Use ping_err to handle all icmp errors except those
1098	 * triggered by ICMP_ECHOREPLY which sent from kernel.
1099	 */
1100	if (icmph->type != ICMP_ECHOREPLY) {
1101		ping_err(skb, offset, info);
1102		return;
1103	}
1104
1105	if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
1106		ipv4_update_pmtu(skb, net, info, 0, 0, IPPROTO_ICMP, 0);
1107	else if (type == ICMP_REDIRECT)
1108		ipv4_redirect(skb, net, 0, 0, IPPROTO_ICMP, 0);
1109}
1110
1111/*
1112 *	This table is the definition of how we handle ICMP.
1113 */
1114static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
1115	[ICMP_ECHOREPLY] = {
1116		.handler = ping_rcv,
1117	},
1118	[1] = {
1119		.handler = icmp_discard,
1120		.error = 1,
1121	},
1122	[2] = {
1123		.handler = icmp_discard,
1124		.error = 1,
1125	},
1126	[ICMP_DEST_UNREACH] = {
1127		.handler = icmp_unreach,
1128		.error = 1,
1129	},
1130	[ICMP_SOURCE_QUENCH] = {
1131		.handler = icmp_unreach,
1132		.error = 1,
1133	},
1134	[ICMP_REDIRECT] = {
1135		.handler = icmp_redirect,
1136		.error = 1,
1137	},
1138	[6] = {
1139		.handler = icmp_discard,
1140		.error = 1,
1141	},
1142	[7] = {
1143		.handler = icmp_discard,
1144		.error = 1,
1145	},
1146	[ICMP_ECHO] = {
1147		.handler = icmp_echo,
1148	},
1149	[9] = {
1150		.handler = icmp_discard,
1151		.error = 1,
1152	},
1153	[10] = {
1154		.handler = icmp_discard,
1155		.error = 1,
1156	},
1157	[ICMP_TIME_EXCEEDED] = {
1158		.handler = icmp_unreach,
1159		.error = 1,
1160	},
1161	[ICMP_PARAMETERPROB] = {
1162		.handler = icmp_unreach,
1163		.error = 1,
1164	},
1165	[ICMP_TIMESTAMP] = {
1166		.handler = icmp_timestamp,
1167	},
1168	[ICMP_TIMESTAMPREPLY] = {
1169		.handler = icmp_discard,
1170	},
1171	[ICMP_INFO_REQUEST] = {
1172		.handler = icmp_discard,
1173	},
1174	[ICMP_INFO_REPLY] = {
1175		.handler = icmp_discard,
1176	},
1177	[ICMP_ADDRESS] = {
1178		.handler = icmp_discard,
1179	},
1180	[ICMP_ADDRESSREPLY] = {
1181		.handler = icmp_discard,
1182	},
1183};
1184
1185static void __net_exit icmp_sk_exit(struct net *net)
1186{
1187	int i;
1188
1189	for_each_possible_cpu(i)
1190		inet_ctl_sock_destroy(*per_cpu_ptr(net->ipv4.icmp_sk, i));
1191	free_percpu(net->ipv4.icmp_sk);
1192	net->ipv4.icmp_sk = NULL;
1193}
1194
1195static int __net_init icmp_sk_init(struct net *net)
1196{
1197	int i, err;
1198
1199	net->ipv4.icmp_sk = alloc_percpu(struct sock *);
1200	if (!net->ipv4.icmp_sk)
 
1201		return -ENOMEM;
1202
1203	for_each_possible_cpu(i) {
1204		struct sock *sk;
1205
1206		err = inet_ctl_sock_create(&sk, PF_INET,
1207					   SOCK_RAW, IPPROTO_ICMP, net);
1208		if (err < 0)
1209			goto fail;
1210
1211		*per_cpu_ptr(net->ipv4.icmp_sk, i) = sk;
1212
1213		/* Enough space for 2 64K ICMP packets, including
1214		 * sk_buff/skb_shared_info struct overhead.
1215		 */
1216		sk->sk_sndbuf =	2 * SKB_TRUESIZE(64 * 1024);
1217
1218		/*
1219		 * Speedup sock_wfree()
1220		 */
1221		sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1222		inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT;
1223	}
1224
1225	/* Control parameters for ECHO replies. */
1226	net->ipv4.sysctl_icmp_echo_ignore_all = 0;
1227	net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1;
1228
1229	/* Control parameter - ignore bogus broadcast responses? */
1230	net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1;
1231
1232	/*
1233	 * 	Configurable global rate limit.
1234	 *
1235	 *	ratelimit defines tokens/packet consumed for dst->rate_token
1236	 *	bucket ratemask defines which icmp types are ratelimited by
1237	 *	setting	it's bit position.
1238	 *
1239	 *	default:
1240	 *	dest unreachable (3), source quench (4),
1241	 *	time exceeded (11), parameter problem (12)
1242	 */
1243
1244	net->ipv4.sysctl_icmp_ratelimit = 1 * HZ;
1245	net->ipv4.sysctl_icmp_ratemask = 0x1818;
1246	net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0;
1247
1248	return 0;
1249
1250fail:
1251	for_each_possible_cpu(i)
1252		inet_ctl_sock_destroy(*per_cpu_ptr(net->ipv4.icmp_sk, i));
1253	free_percpu(net->ipv4.icmp_sk);
1254	return err;
1255}
1256
1257static struct pernet_operations __net_initdata icmp_sk_ops = {
1258       .init = icmp_sk_init,
1259       .exit = icmp_sk_exit,
1260};
1261
1262int __init icmp_init(void)
1263{
1264	return register_pernet_subsys(&icmp_sk_ops);
1265}