/*
* NET3: Implementation of the ICMP protocol layer.
*
* Alan Cox, <alan@redhat.com>
*
* Version: $Id: icmp.c,v 1.71 2000/08/02 06:01:48 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:
* 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
*
* RFC1122 (Host Requirements -- Comm. Layer) Status:
* (boy, are there a lot of rules for ICMP)
* 3.2.2 (Generic ICMP stuff)
* MUST discard messages of unknown type. (OK)
* MUST copy at least the first 8 bytes from the offending packet
* when sending ICMP errors. (OBSOLETE -- see RFC1812)
* MUST pass received ICMP errors up to protocol level. (OK)
* SHOULD send ICMP errors with TOS == 0. (OBSOLETE -- see RFC1812)
* MUST NOT send ICMP errors in reply to:
* ICMP errors (OK)
* Broadcast/multicast datagrams (OK)
* MAC broadcasts (OK)
* Non-initial fragments (OK)
* Datagram with a source address that isn't a single host. (OK)
* 3.2.2.1 (Destination Unreachable)
* All the rules govern the IP layer, and are dealt with in ip.c, not here.
* 3.2.2.2 (Redirect)
* Host SHOULD NOT send ICMP_REDIRECTs. (OK)
* MUST update routing table in response to host or network redirects.
* (host OK, network OBSOLETE)
* SHOULD drop redirects if they're not from directly connected gateway
* (OK -- we drop it if it's not from our old gateway, which is close
* enough)
* 3.2.2.3 (Source Quench)
* MUST pass incoming SOURCE_QUENCHs to transport layer (OK)
* Other requirements are dealt with at the transport layer.
* 3.2.2.4 (Time Exceeded)
* MUST pass TIME_EXCEEDED to transport layer (OK)
* Other requirements dealt with at IP (generating TIME_EXCEEDED).
* 3.2.2.5 (Parameter Problem)
* SHOULD generate these (OK)
* MUST pass received PARAMPROBLEM to transport layer (NOT YET)
* [Solaris 2.X seems to assert EPROTO when this occurs] -- AC
* 3.2.2.6 (Echo Request/Reply)
* MUST reply to ECHO_REQUEST, and give app to do ECHO stuff (OK, OK)
* MAY discard broadcast ECHO_REQUESTs. (Configurable with a sysctl.)
* MUST reply using same source address as the request was sent to.
* We're OK for unicast ECHOs, and it doesn't say anything about
* how to handle broadcast ones, since it's optional.
* MUST copy data from REQUEST to REPLY (OK)
* unless it would require illegal fragmentation (OK)
* MUST pass REPLYs to transport/user layer (OK)
* MUST use any provided source route (reversed) for REPLY. (NOT YET)
* 3.2.2.7 (Information Request/Reply)
* MUST NOT implement this. (I guess that means silently discard...?) (OK)
* 3.2.2.8 (Timestamp Request/Reply)
* MAY implement (OK)
* SHOULD be in-kernel for "minimum variability" (OK)
* MAY discard broadcast REQUESTs. (OK, but see source for inconsistency)
* MUST reply using same source address as the request was sent to. (OK)
* MUST reverse source route, as per ECHO (NOT YET)
* MUST pass REPLYs to transport/user layer (requires RAW, just like
* ECHO) (OK)
* MUST update clock for timestamp at least 15 times/sec (OK)
* MUST be "correct within a few minutes" (OK)
* 3.2.2.9 (Address Mask Request/Reply)
* MAY implement (OK)
* MUST send a broadcast REQUEST if using this system to set netmask
* (OK... we don't use it)
* MUST discard received REPLYs if not using this system (OK)
* MUST NOT send replies unless specifically made agent for this sort
* of thing. (OK)
*
*
* RFC 1812 (IPv4 Router Requirements) Status (even longer):
* 4.3.2.1 (Unknown Message Types)
* MUST pass messages of unknown type to ICMP user iface or silently discard
* them (OK)
* 4.3.2.2 (ICMP Message TTL)
* MUST initialize TTL when originating an ICMP message (OK)
* 4.3.2.3 (Original Message Header)
* SHOULD copy as much data from the offending packet as possible without
* the length of the ICMP datagram exceeding 576 bytes (OK)
* MUST leave original IP header of the offending packet, but we're not
* required to undo modifications made (OK)
* 4.3.2.4 (Original Message Source Address)
* MUST use one of addresses for the interface the orig. packet arrived as
* source address (OK)
* 4.3.2.5 (TOS and Precedence)
* SHOULD leave TOS set to the same value unless the packet would be
* discarded for that reason (OK)
* MUST use TOS=0 if not possible to leave original value (OK)
* MUST leave IP Precedence for Source Quench messages (OK -- not sent
* at all)
* SHOULD use IP Precedence = 6 (Internetwork Control) or 7 (Network Control)
* for all other error messages (OK, we use 6)
* MAY allow configuration of IP Precedence (OK -- not done)
* MUST leave IP Precedence and TOS for reply messages (OK)
* 4.3.2.6 (Source Route)
* SHOULD use reverse source route UNLESS sending Parameter Problem on source
* routing and UNLESS the packet would be immediately discarded (NOT YET)
* 4.3.2.7 (When Not to Send ICMP Errors)
* MUST NOT send ICMP errors in reply to:
* ICMP errors (OK)
* Packets failing IP header validation tests unless otherwise noted (OK)
* Broadcast/multicast datagrams (OK)
* MAC broadcasts (OK)
* Non-initial fragments (OK)
* Datagram with a source address that isn't a single host. (OK)
* 4.3.2.8 (Rate Limiting)
* SHOULD be able to limit error message rate (OK)
* SHOULD allow setting of rate limits (OK, in the source)
* 4.3.3.1 (Destination Unreachable)
* All the rules govern the IP layer, and are dealt with in ip.c, not here.
* 4.3.3.2 (Redirect)
* MAY ignore ICMP Redirects if running a routing protocol or if forwarding
* is enabled on the interface (OK -- ignores)
* 4.3.3.3 (Source Quench)
* SHOULD NOT originate SQ messages (OK)
* MUST be able to limit SQ rate if originates them (OK as we don't
* send them)
* MAY ignore SQ messages it receives (OK -- we don't)
* 4.3.3.4 (Time Exceeded)
* Requirements dealt with at IP (generating TIME_EXCEEDED).
* 4.3.3.5 (Parameter Problem)
* MUST generate these for all errors not covered by other messages (OK)
* MUST include original value of the value pointed by (OK)
* 4.3.3.6 (Echo Request)
* MUST implement echo server function (OK)
* MUST process at ER of at least max(576, MTU) (OK)
* MAY reject broadcast/multicast ER's (We don't, but that's OK)
* SHOULD have a config option for silently ignoring ER's (OK)
* MUST have a default value for the above switch = NO (OK)
* MUST have application layer interface for Echo Request/Reply (OK)
* MUST reply using same source address as the request was sent to.
* We're OK for unicast ECHOs, and it doesn't say anything about
* how to handle broadcast ones, since it's optional.
* MUST copy data from Request to Reply (OK)
* SHOULD update Record Route / Timestamp options (??)
* MUST use reversed Source Route for Reply if possible (NOT YET)
* 4.3.3.7 (Information Request/Reply)
* SHOULD NOT originate or respond to these (OK)
* 4.3.3.8 (Timestamp / Timestamp Reply)
* MAY implement (OK)
* MUST reply to every Timestamp message received (OK)
* MAY discard broadcast REQUESTs. (OK, but see source for inconsistency)
* MUST reply using same source address as the request was sent to. (OK)
* MUST use reversed Source Route if possible (NOT YET)
* SHOULD update Record Route / Timestamp options (??)
* MUST pass REPLYs to transport/user layer (requires RAW, just like
* ECHO) (OK)
* MUST update clock for timestamp at least 16 times/sec (OK)
* MUST be "correct within a few minutes" (OK)
* 4.3.3.9 (Address Mask Request/Reply)
* MUST have support for receiving AMRq and responding with AMRe (OK,
* but only as a compile-time option)
* SHOULD have option for each interface for AMRe's, MUST default to
* NO (NOT YET)
* MUST NOT reply to AMRq before knows the correct AM (OK)
* MUST NOT respond to AMRq with source address 0.0.0.0 on physical
* interfaces having multiple logical i-faces with different masks
* (NOT YET)
* SHOULD examine all AMRe's it receives and check them (NOT YET)
* SHOULD log invalid AMRe's (AM+sender) (NOT YET)
* MUST NOT use contents of AMRe to determine correct AM (OK)
* MAY broadcast AMRe's after having configured address masks (OK -- doesn't)
* MUST NOT do broadcast AMRe's if not set by extra option (OK, no option)
* MUST use the { <NetPrefix>, -1 } form of broadcast addresses (OK)
* 4.3.3.10 (Router Advertisement and Solicitations)
* MUST support router part of Router Discovery Protocol on all networks we
* support broadcast or multicast addressing. (OK -- done by gated)
* MUST have all config parameters with the respective defaults (OK)
* 5.2.7.1 (Destination Unreachable)
* MUST generate DU's (OK)
* SHOULD choose a best-match response code (OK)
* SHOULD NOT generate Host Isolated codes (OK)
* SHOULD use Communication Administratively Prohibited when administratively
* filtering packets (NOT YET -- bug-to-bug compatibility)
* MAY include config option for not generating the above and silently
* discard the packets instead (OK)
* MAY include config option for not generating Precedence Violation and
* Precedence Cutoff messages (OK as we don't generate them at all)
* MUST use Host Unreachable or Dest. Host Unknown codes whenever other hosts
* on the same network might be reachable (OK -- no net unreach's at all)
* MUST use new form of Fragmentation Needed and DF Set messages (OK)
* 5.2.7.2 (Redirect)
* MUST NOT generate network redirects (OK)
* MUST be able to generate host redirects (OK)
* SHOULD be able to generate Host+TOS redirects (NO as we don't use TOS)
* MUST have an option to use Host redirects instead of Host+TOS ones (OK as
* no Host+TOS Redirects are used)
* MUST NOT generate redirects unless forwarding to the same i-face and the
* dest. address is on the same subnet as the src. address and no source
* routing is in use. (OK)
* MUST NOT follow redirects when using a routing protocol (OK)
* MAY use redirects if not using a routing protocol (OK, compile-time option)
* MUST comply to Host Requirements when not acting as a router (OK)
* 5.2.7.3 (Time Exceeded)
* MUST generate Time Exceeded Code 0 when discarding packet due to TTL=0 (OK)
* MAY have a per-interface option to disable origination of TE messages, but
* it MUST default to "originate" (OK -- we don't support it)
*/
#include <linux/config.h>
#include <linux/types.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/fcntl.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/string.h>
#include <linux/netfilter_ipv4.h>
#include <net/snmp.h>
#include <net/ip.h>
#include <net/route.h>
#include <net/protocol.h>
#include <net/icmp.h>
#include <net/tcp.h>
#include <net/udp.h>
#include <net/raw.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <linux/errno.h>
#include <linux/timer.h>
#include <linux/init.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <net/checksum.h>
#define min(a,b) ((a)<(b)?(a):(b))
/*
* Statistics
*/
struct icmp_mib icmp_statistics[NR_CPUS*2];
/* An array of errno for error messages from dest unreach. */
/* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOS_UNREACH and SR_FAIELD MUST be considered 'transient errs'. */
struct icmp_err icmp_err_convert[] = {
{ ENETUNREACH, 0 }, /* ICMP_NET_UNREACH */
{ EHOSTUNREACH, 0 }, /* ICMP_HOST_UNREACH */
{ ENOPROTOOPT, 1 }, /* ICMP_PROT_UNREACH */
{ ECONNREFUSED, 1 }, /* ICMP_PORT_UNREACH */
{ EMSGSIZE, 0 }, /* ICMP_FRAG_NEEDED */
{ EOPNOTSUPP, 0 }, /* ICMP_SR_FAILED */
{ ENETUNREACH, 1 }, /* ICMP_NET_UNKNOWN */
{ EHOSTDOWN, 1 }, /* ICMP_HOST_UNKNOWN */
{ ENONET, 1 }, /* ICMP_HOST_ISOLATED */
{ ENETUNREACH, 1 }, /* ICMP_NET_ANO */
{ EHOSTUNREACH, 1 }, /* ICMP_HOST_ANO */
{ ENETUNREACH, 0 }, /* ICMP_NET_UNR_TOS */
{ EHOSTUNREACH, 0 }, /* ICMP_HOST_UNR_TOS */
{ EHOSTUNREACH, 1 }, /* ICMP_PKT_FILTERED */
{ EHOSTUNREACH, 1 }, /* ICMP_PREC_VIOLATION */
{ EHOSTUNREACH, 1 } /* ICMP_PREC_CUTOFF */
};
/* Control parameters for ECHO relies. */
int sysctl_icmp_echo_ignore_all = 0;
int sysctl_icmp_echo_ignore_broadcasts = 0;
/* Control parameter - ignore bogus broadcast responses? */
int sysctl_icmp_ignore_bogus_error_responses =0;
/*
* ICMP control array. This specifies what to do with each ICMP.
*/
struct icmp_control
{
unsigned long *output; /* Address to increment on output */
unsigned long *input; /* Address to increment on input */
void (*handler)(struct icmphdr *icmph, struct sk_buff *skb, int len);
short error; /* This ICMP is classed as an error message */
int *timeout; /* Rate limit */
};
static struct icmp_control icmp_pointers[NR_ICMP_TYPES+1];
/*
* The ICMP socket. This is the most convenient way to flow control
* our ICMP output as well as maintain a clean interface throughout
* all layers. All Socketless IP sends will soon be gone.
*/
struct inode icmp_inode;
struct socket *icmp_socket=&icmp_inode.u.socket_i;
/* ICMPv4 socket is only a bit non-reenterable (unlike ICMPv6,
which is strongly non-reenterable). A bit later it will be made
reenterable and the lock may be removed then.
*/
static int icmp_xmit_holder = -1;
350 static int icmp_xmit_lock_bh(void)
{
352 if (!spin_trylock(&icmp_socket->sk->lock.slock)) {
353 if (icmp_xmit_holder == smp_processor_id())
354 return -EAGAIN;
spin_lock(&icmp_socket->sk->lock.slock);
}
icmp_xmit_holder = smp_processor_id();
358 return 0;
}
361 static __inline__ int icmp_xmit_lock(void)
{
int ret;
364 local_bh_disable();
ret = icmp_xmit_lock_bh();
366 if (ret)
367 local_bh_enable();
368 return ret;
}
371 static void icmp_xmit_unlock_bh(void)
{
icmp_xmit_holder = -1;
374 spin_unlock(&icmp_socket->sk->lock.slock);
}
377 static __inline__ void icmp_xmit_unlock(void)
{
icmp_xmit_unlock_bh();
380 local_bh_enable();
}
/*
* Send an ICMP frame.
*/
/*
* Check transmit rate limitation for given message.
* The rate information is held in the destination cache now.
* This function is generic and could be used for other purposes
* too. It uses a Token bucket filter as suggested by Alexey Kuznetsov.
*
* Note that the same dst_entry fields are modified by functions in
* route.c too, but these work for packet destinations while xrlim_allow
* works for icmp destinations. This means the rate limiting information
* for one "ip object" is shared.
*
* 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
411 int xrlim_allow(struct dst_entry *dst, int timeout)
{
unsigned long now;
now = jiffies;
dst->rate_tokens += now - dst->rate_last;
dst->rate_last = now;
418 if (dst->rate_tokens > XRLIM_BURST_FACTOR*timeout)
dst->rate_tokens = XRLIM_BURST_FACTOR*timeout;
420 if (dst->rate_tokens >= timeout) {
dst->rate_tokens -= timeout;
422 return 1;
}
424 return 0;
}
427 static inline int icmpv4_xrlim_allow(struct rtable *rt, int type, int code)
{
struct dst_entry *dst = &rt->u.dst;
431 if (type > NR_ICMP_TYPES || !icmp_pointers[type].timeout)
432 return 1;
/* Don't limit PMTU discovery. */
435 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
436 return 1;
/* Redirect has its own rate limit mechanism */
439 if (type == ICMP_REDIRECT)
440 return 1;
/* No rate limit on loopback */
443 if (dst->dev && (dst->dev->flags&IFF_LOOPBACK))
444 return 1;
446 return xrlim_allow(dst, *(icmp_pointers[type].timeout));
}
/*
* Maintain the counters used in the SNMP statistics for outgoing ICMP
*/
453 static void icmp_out_count(int type)
{
455 if (type>NR_ICMP_TYPES)
456 return;
(icmp_pointers[type].output)[(smp_processor_id()*2+!in_softirq())*sizeof(struct icmp_mib)/sizeof(unsigned long)]++;
ICMP_INC_STATS(IcmpOutMsgs);
}
/*
* Checksum each fragment, and on the first include the headers and final checksum.
*/
465 static int icmp_glue_bits(const void *p, char *to, unsigned int offset, unsigned int fraglen)
{
struct icmp_bxm *icmp_param = (struct icmp_bxm *)p;
struct icmphdr *icmph;
unsigned long csum;
471 if (offset) {
icmp_param->csum=csum_partial_copy_nocheck(icmp_param->data_ptr+offset-sizeof(struct icmphdr),
to, fraglen,icmp_param->csum);
474 return 0;
}
/*
* First fragment includes header. Note that we've done
* the other fragments first, so that we get the checksum
* for the whole packet here.
*/
csum = csum_partial_copy_nocheck((void *)&icmp_param->icmph,
to, sizeof(struct icmphdr),
icmp_param->csum);
csum = csum_partial_copy_nocheck(icmp_param->data_ptr,
to+sizeof(struct icmphdr),
fraglen-sizeof(struct icmphdr), csum);
icmph=(struct icmphdr *)to;
icmph->checksum = csum_fold(csum);
490 return 0;
}
/*
* Driving logic for building and sending ICMP messages.
*/
497 void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
{
struct sock *sk=icmp_socket->sk;
struct ipcm_cookie ipc;
struct rtable *rt = (struct rtable*)skb->dst;
u32 daddr;
504 if (ip_options_echo(&icmp_param->replyopts, skb))
505 return;
507 if (icmp_xmit_lock_bh())
508 return;
icmp_param->icmph.checksum=0;
icmp_param->csum=0;
icmp_out_count(icmp_param->icmph.type);
sk->protinfo.af_inet.tos = skb->nh.iph->tos;
daddr = ipc.addr = rt->rt_src;
ipc.opt = NULL;
517 if (icmp_param->replyopts.optlen) {
ipc.opt = &icmp_param->replyopts;
519 if (ipc.opt->srr)
daddr = icmp_param->replyopts.faddr;
}
522 if (ip_route_output(&rt, daddr, rt->rt_spec_dst, RT_TOS(skb->nh.iph->tos), 0))
523 goto out;
if (icmpv4_xrlim_allow(rt, icmp_param->icmph.type,
525 icmp_param->icmph.code)) {
ip_build_xmit(sk, icmp_glue_bits, icmp_param,
icmp_param->data_len+sizeof(struct icmphdr),
&ipc, rt, MSG_DONTWAIT);
}
ip_rt_put(rt);
out:
icmp_xmit_unlock_bh();
}
/*
* Send an ICMP message in response to a situation
*
* RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. MAY send more (we do).
* MUST NOT change this header information.
* MUST NOT reply to a multicast/broadcast IP address.
* MUST NOT reply to a multicast/broadcast MAC address.
* MUST reply to only the first fragment.
*/
546 void icmp_send(struct sk_buff *skb_in, int type, int code, unsigned long info)
{
struct iphdr *iph;
struct icmphdr *icmph;
int room;
struct icmp_bxm icmp_param;
struct rtable *rt = (struct rtable*)skb_in->dst;
struct ipcm_cookie ipc;
u32 saddr;
u8 tos;
557 if (!rt)
558 return;
/*
* Find the original header
*/
iph = skb_in->nh.iph;
/*
* No replies to physical multicast/broadcast
*/
568 if (skb_in->pkt_type!=PACKET_HOST)
569 return;
/*
* Now check at the protocol level
*/
574 if (rt->rt_flags&(RTCF_BROADCAST|RTCF_MULTICAST))
575 return;
/*
* Only reply to fragment 0. We byte re-order the constant
* mask for efficiency.
*/
581 if (iph->frag_off&htons(IP_OFFSET))
582 return;
/*
* If we send an ICMP error to an ICMP error a mess would result..
*/
587 if (icmp_pointers[type].error) {
/*
* We are an error, check if we are replying to an ICMP error
*/
591 if (iph->protocol==IPPROTO_ICMP) {
icmph = (struct icmphdr *)((char *)iph + (iph->ihl<<2));
/*
* Assume any unknown ICMP type is an error. This isn't
* specified by the RFC, but think about it..
*/
597 if (icmph->type>NR_ICMP_TYPES || icmp_pointers[icmph->type].error)
598 return;
}
}
603 if (icmp_xmit_lock())
604 return;
/*
* Construct source address and options.
*/
#ifdef CONFIG_IP_ROUTE_NAT
/*
* Restore original addresses if packet has been translated.
*/
if (rt->rt_flags&RTCF_NAT && IPCB(skb_in)->flags&IPSKB_TRANSLATED) {
iph->daddr = rt->key.dst;
iph->saddr = rt->key.src;
}
#endif
saddr = iph->daddr;
621 if (!(rt->rt_flags & RTCF_LOCAL))
saddr = 0;
tos = icmp_pointers[type].error ?
((iph->tos & IPTOS_TOS_MASK) | IPTOS_PREC_INTERNETCONTROL) :
iph->tos;
/* XXX: use a more aggressive expire for routes created by
* this call (not longer than the rate limit timeout).
* It could be also worthwhile to not put them into ipv4
* fast routing cache at first. Otherwise an attacker can
* grow the routing table.
*/
634 if (ip_route_output(&rt, iph->saddr, saddr, RT_TOS(tos), 0))
635 goto out;
637 if (ip_options_echo(&icmp_param.replyopts, skb_in))
638 goto ende;
/*
* Prepare data for ICMP header.
*/
icmp_param.icmph.type=type;
icmp_param.icmph.code=code;
icmp_param.icmph.un.gateway = info;
icmp_param.icmph.checksum=0;
icmp_param.csum=0;
icmp_param.data_ptr=iph;
icmp_out_count(icmp_param.icmph.type);
icmp_socket->sk->protinfo.af_inet.tos = tos;
ipc.addr = iph->saddr;
ipc.opt = &icmp_param.replyopts;
655 if (icmp_param.replyopts.srr) {
ip_rt_put(rt);
657 if (ip_route_output(&rt, icmp_param.replyopts.faddr, saddr, RT_TOS(tos), 0))
658 goto out;
}
661 if (!icmpv4_xrlim_allow(rt, type, code))
662 goto ende;
/* RFC says return as much as we can without exceeding 576 bytes. */
room = rt->u.dst.pmtu;
667 if (room > 576)
room = 576;
room -= sizeof(struct iphdr) + icmp_param.replyopts.optlen;
room -= sizeof(struct icmphdr);
icmp_param.data_len=(skb_in->tail-(u8*)iph);
673 if (icmp_param.data_len > room)
icmp_param.data_len = room;
ip_build_xmit(icmp_socket->sk, icmp_glue_bits, &icmp_param,
icmp_param.data_len+sizeof(struct icmphdr),
&ipc, rt, MSG_DONTWAIT);
ende:
ip_rt_put(rt);
out:
icmp_xmit_unlock();
}
/*
* Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEED, and ICMP_QUENCH.
*/
691 static void icmp_unreach(struct icmphdr *icmph, struct sk_buff *skb, int len)
{
struct iphdr *iph;
int hash;
struct inet_protocol *ipprot;
unsigned char *dp;
struct sock *raw_sk;
/*
* Incomplete header ?
* Only checks for the IP header, there should be an
* additional check for longer headers in upper levels.
*/
705 if(len<sizeof(struct iphdr)) {
ICMP_INC_STATS_BH(IcmpInErrors);
707 return;
}
iph = (struct iphdr *) (icmph + 1);
dp = (unsigned char*)iph;
713 if(icmph->type==ICMP_DEST_UNREACH) {
714 switch(icmph->code & 15) {
715 case ICMP_NET_UNREACH:
716 break;
717 case ICMP_HOST_UNREACH:
718 break;
719 case ICMP_PROT_UNREACH:
720 break;
721 case ICMP_PORT_UNREACH:
722 break;
723 case ICMP_FRAG_NEEDED:
724 if (ipv4_config.no_pmtu_disc) {
725 if (net_ratelimit())
printk(KERN_INFO "ICMP: %u.%u.%u.%u: fragmentation needed and DF set.\n",
NIPQUAD(iph->daddr));
728 } else {
unsigned short new_mtu;
new_mtu = ip_rt_frag_needed(iph, ntohs(icmph->un.frag.mtu));
731 if (!new_mtu)
732 return;
icmph->un.frag.mtu = htons(new_mtu);
}
735 break;
736 case ICMP_SR_FAILED:
737 if (net_ratelimit())
printk(KERN_INFO "ICMP: %u.%u.%u.%u: Source Route Failed.\n", NIPQUAD(iph->daddr));
739 break;
740 default:
741 break;
}
743 if (icmph->code>NR_ICMP_UNREACH)
744 return;
}
/*
* 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.
*/
762 if (!sysctl_icmp_ignore_bogus_error_responses)
{
765 if (inet_addr_type(iph->daddr) == RTN_BROADCAST)
{
767 if (net_ratelimit())
printk(KERN_WARNING "%u.%u.%u.%u sent an invalid ICMP error to a broadcast.\n",
NIPQUAD(skb->nh.iph->saddr));
770 return;
}
}
/*
* Deliver ICMP message to raw sockets. Pretty useless feature?
*/
/* Note: See raw.c and net/raw.h, RAWV4_HTABLE_SIZE==MAX_INET_PROTOS */
hash = iph->protocol & (MAX_INET_PROTOS - 1);
read_lock(&raw_v4_lock);
781 if ((raw_sk = raw_v4_htable[hash]) != NULL)
{
while ((raw_sk = __raw_v4_lookup(raw_sk, iph->protocol, iph->saddr,
784 iph->daddr, skb->dev->ifindex)) != NULL) {
raw_err(raw_sk, skb);
raw_sk = raw_sk->next;
}
}
789 read_unlock(&raw_v4_lock);
/*
* This can't change while we are doing it.
* Callers have obtained BR_NETPROTO_LOCK so
* we are OK.
*/
ipprot = (struct inet_protocol *) inet_protos[hash];
798 while(ipprot != NULL) {
struct inet_protocol *nextip;
nextip = (struct inet_protocol *) ipprot->next;
/*
* Pass it off to everyone who wants it.
*/
/* RFC1122: OK. Passes appropriate ICMP errors to the */
/* appropriate protocol layer (MUST), as per 3.2.2. */
810 if (iph->protocol == ipprot->protocol && ipprot->err_handler)
ipprot->err_handler(skb, dp, len);
ipprot = nextip;
}
}
/*
* Handle ICMP_REDIRECT.
*/
822 static void icmp_redirect(struct icmphdr *icmph, struct sk_buff *skb, int len)
{
struct iphdr *iph;
unsigned long ip;
827 if (len < sizeof(struct iphdr)) {
ICMP_INC_STATS_BH(IcmpInErrors);
829 return;
}
/*
* Get the copied header of the packet that caused the redirect
*/
iph = (struct iphdr *) (icmph + 1);
ip = iph->daddr;
839 switch(icmph->code & 7) {
840 case ICMP_REDIR_NET:
841 case ICMP_REDIR_NETTOS:
/*
* As per RFC recommendations now handle it as
* a host redirect.
*/
847 case ICMP_REDIR_HOST:
848 case ICMP_REDIR_HOSTTOS:
ip_rt_redirect(skb->nh.iph->saddr, ip, icmph->un.gateway, iph->saddr, iph->tos, skb->dev);
850 break;
851 default:
852 break;
}
}
/*
* Handle ICMP_ECHO ("ping") requests.
*
* RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo requests.
* RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be included in the reply.
* RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring echo requests, MUST have default=NOT.
* See also WRT handling of options once they are done and working.
*/
865 static void icmp_echo(struct icmphdr *icmph, struct sk_buff *skb, int len)
{
867 if (!sysctl_icmp_echo_ignore_all) {
struct icmp_bxm icmp_param;
icmp_param.icmph=*icmph;
icmp_param.icmph.type=ICMP_ECHOREPLY;
icmp_param.data_ptr=(icmph+1);
icmp_param.data_len=len;
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.
*/
886 static void icmp_timestamp(struct icmphdr *icmph, struct sk_buff *skb, int len)
{
struct timeval tv;
__u32 times[3]; /* So the new timestamp works on ALPHA's.. */
struct icmp_bxm icmp_param;
/*
* Too short.
*/
896 if(len<12) {
ICMP_INC_STATS_BH(IcmpInErrors);
898 return;
}
/*
* Fill in the current time as ms since midnight UT:
*/
do_gettimeofday(&tv);
times[1] = htonl((tv.tv_sec % 86400) * 1000 + tv.tv_usec / 1000);
times[2] = times[1];
memcpy((void *)×[0], icmph+1, 4); /* Incoming stamp */
icmp_param.icmph=*icmph;
icmp_param.icmph.type=ICMP_TIMESTAMPREPLY;
icmp_param.icmph.code=0;
icmp_param.data_ptr=×
icmp_param.data_len=12;
icmp_reply(&icmp_param, skb);
}
/*
* Handle ICMP_ADDRESS_MASK requests. (RFC950)
*
* RFC1122 (3.2.2.9). A host MUST only send replies to
* ADDRESS_MASK requests if it's been configured as an address mask
* agent. Receiving a request doesn't constitute implicit permission to
* act as one. Of course, implementing this correctly requires (SHOULD)
* a way to turn the functionality on and off. Another one for sysctl(),
* I guess. -- MS
*
* RFC1812 (4.3.3.9). A router MUST implement it.
* A router SHOULD have switch turning it on/off.
* This switch MUST be ON by default.
*
* Gratuitous replies, zero-source replies are not implemented,
* that complies with RFC. DO NOT implement them!!! All the idea
* of broadcast addrmask replies as specified in RFC950 is broken.
* The problem is that it is not uncommon to have several prefixes
* on one physical interface. Moreover, addrmask agent can even be
* not aware of existing another prefixes.
* If source is zero, addrmask agent cannot choose correct prefix.
* Gratuitous mask announcements suffer from the same problem.
* RFC1812 explains it, but still allows to use ADDRMASK,
* that is pretty silly. --ANK
*
* All these rules are so bizarre, that I removed kernel addrmask
* support at all. It is wrong, it is obsolete, nobody uses it in
* any case. --ANK
*
* Furthermore you can do it with a usermode address agent program
* anyway...
*/
951 static void icmp_address(struct icmphdr *icmph, struct sk_buff *skb, int len)
{
#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.
*/
964 static void icmp_address_reply(struct icmphdr *icmph, struct sk_buff *skb, int len)
{
struct rtable *rt = (struct rtable*)skb->dst;
struct net_device *dev = skb->dev;
struct in_device *in_dev;
struct in_ifaddr *ifa;
u32 mask;
972 if (len < 4 || !(rt->rt_flags&RTCF_DIRECTSRC))
973 return;
in_dev = in_dev_get(dev);
976 if (!in_dev)
977 return;
read_lock(&in_dev->lock);
if (in_dev->ifa_list &&
IN_DEV_LOG_MARTIANS(in_dev) &&
981 IN_DEV_FORWARD(in_dev)) {
mask = *(u32*)&icmph[1];
984 for (ifa=in_dev->ifa_list; ifa; ifa = ifa->ifa_next) {
985 if (mask == ifa->ifa_mask && inet_ifa_match(rt->rt_src, ifa))
986 break;
}
988 if (!ifa && net_ratelimit()) {
printk(KERN_INFO "Wrong address mask %u.%u.%u.%u from %s/%u.%u.%u.%u\n",
NIPQUAD(mask), dev->name, NIPQUAD(rt->rt_src));
}
}
993 read_unlock(&in_dev->lock);
in_dev_put(in_dev);
}
997 static void icmp_discard(struct icmphdr *icmph, struct sk_buff *skb, int len)
{
}
/*
* Deal with incoming ICMP packets.
*/
1005 int icmp_rcv(struct sk_buff *skb, unsigned short len)
{
struct icmphdr *icmph = skb->h.icmph;
struct rtable *rt = (struct rtable*)skb->dst;
ICMP_INC_STATS_BH(IcmpInMsgs);
/*
* 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(len < sizeof(struct icmphdr) ||
ip_compute_csum((unsigned char *) icmph, len) ||
1019 icmph->type > NR_ICMP_TYPES)
1020 goto error;
/*
* Parse the ICMP message
*/
1026 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 &&
1034 sysctl_icmp_echo_ignore_broadcasts) {
1035 goto error;
}
if (icmph->type != ICMP_ECHO &&
icmph->type != ICMP_TIMESTAMP &&
icmph->type != ICMP_ADDRESS &&
1040 icmph->type != ICMP_ADDRESSREPLY) {
1041 goto error;
}
}
len -= sizeof(struct icmphdr);
icmp_pointers[icmph->type].input[smp_processor_id()*2*sizeof(struct icmp_mib)/sizeof(unsigned long)]++;
(icmp_pointers[icmph->type].handler)(icmph, skb, len);
drop:
kfree_skb(skb);
1051 return 0;
error:
ICMP_INC_STATS_BH(IcmpInErrors);
1054 goto drop;
}
/*
* A spare long used to speed up statistics updating
*/
static unsigned long dummy;
/*
* Configurable rate limits.
* Someone should check if these default values are correct.
* Note that these values interact with the routing cache GC timeout.
* If you chose them too high they won't take effect, because the
* dst_entry gets expired too early. The same should happen when
* the cache grows too big.
*/
int sysctl_icmp_destunreach_time = 1*HZ;
int sysctl_icmp_timeexceed_time = 1*HZ;
int sysctl_icmp_paramprob_time = 1*HZ;
int sysctl_icmp_echoreply_time = 0; /* don't limit it per default. */
/*
* This table is the definition of how we handle ICMP.
*/
static struct icmp_control icmp_pointers[NR_ICMP_TYPES+1] = {
/* ECHO REPLY (0) */
{ &icmp_statistics[0].IcmpOutEchoReps, &icmp_statistics[0].IcmpInEchoReps, icmp_discard, 0, &sysctl_icmp_echoreply_time},
{ &dummy, &icmp_statistics[0].IcmpInErrors, icmp_discard, 1, },
{ &dummy, &icmp_statistics[0].IcmpInErrors, icmp_discard, 1, },
/* DEST UNREACH (3) */
{ &icmp_statistics[0].IcmpOutDestUnreachs, &icmp_statistics[0].IcmpInDestUnreachs, icmp_unreach, 1, &sysctl_icmp_destunreach_time },
/* SOURCE QUENCH (4) */
{ &icmp_statistics[0].IcmpOutSrcQuenchs, &icmp_statistics[0].IcmpInSrcQuenchs, icmp_unreach, 1, },
/* REDIRECT (5) */
{ &icmp_statistics[0].IcmpOutRedirects, &icmp_statistics[0].IcmpInRedirects, icmp_redirect, 1, },
{ &dummy, &icmp_statistics[0].IcmpInErrors, icmp_discard, 1, },
{ &dummy, &icmp_statistics[0].IcmpInErrors, icmp_discard, 1, },
/* ECHO (8) */
{ &icmp_statistics[0].IcmpOutEchos, &icmp_statistics[0].IcmpInEchos, icmp_echo, 0, },
{ &dummy, &icmp_statistics[0].IcmpInErrors, icmp_discard, 1, },
{ &dummy, &icmp_statistics[0].IcmpInErrors, icmp_discard, 1, },
/* TIME EXCEEDED (11) */
{ &icmp_statistics[0].IcmpOutTimeExcds, &icmp_statistics[0].IcmpInTimeExcds, icmp_unreach, 1, &sysctl_icmp_timeexceed_time },
/* PARAMETER PROBLEM (12) */
{ &icmp_statistics[0].IcmpOutParmProbs, &icmp_statistics[0].IcmpInParmProbs, icmp_unreach, 1, &sysctl_icmp_paramprob_time },
/* TIMESTAMP (13) */
{ &icmp_statistics[0].IcmpOutTimestamps, &icmp_statistics[0].IcmpInTimestamps, icmp_timestamp, 0, },
/* TIMESTAMP REPLY (14) */
{ &icmp_statistics[0].IcmpOutTimestampReps, &icmp_statistics[0].IcmpInTimestampReps, icmp_discard, 0, },
/* INFO (15) */
{ &dummy, &dummy, icmp_discard, 0, },
/* INFO REPLY (16) */
{ &dummy, &dummy, icmp_discard, 0, },
/* ADDR MASK (17) */
{ &icmp_statistics[0].IcmpOutAddrMasks, &icmp_statistics[0].IcmpInAddrMasks, icmp_address, 0, },
/* ADDR MASK REPLY (18) */
{ &icmp_statistics[0].IcmpOutAddrMaskReps, &icmp_statistics[0].IcmpInAddrMaskReps, icmp_address_reply, 0, }
};
1115 void __init icmp_init(struct net_proto_family *ops)
{
int err;
icmp_inode.i_mode = S_IFSOCK;
icmp_inode.i_sock = 1;
icmp_inode.i_uid = 0;
icmp_inode.i_gid = 0;
init_waitqueue_head(&icmp_inode.i_wait);
init_waitqueue_head(&icmp_inode.u.socket_i.wait);
icmp_socket->inode = &icmp_inode;
icmp_socket->state = SS_UNCONNECTED;
icmp_socket->type=SOCK_RAW;
1130 if ((err=ops->create(icmp_socket, IPPROTO_ICMP))<0)
panic("Failed to create the ICMP control socket.\n");
icmp_socket->sk->allocation=GFP_ATOMIC;
icmp_socket->sk->sndbuf = SK_WMEM_MAX*2;
icmp_socket->sk->protinfo.af_inet.ttl = MAXTTL;
/* Unhash it so that IP input processing does not even
* see it, we do not wish this socket to see incoming
* packets.
*/
icmp_socket->sk->prot->unhash(icmp_socket->sk);
}