kernel_optimize_test/net/ipv4/icmp.c
Patrick McHardy d8cf27287a [IPV4]: icmp: fix crash with sysctl_icmp_errors_use_inbound_ifaddr
When icmp_send is called on the local output path before the
packet hits ip_output, skb->dev is not set, causing a crash
when sysctl_icmp_errors_use_inbound_ifaddr is set. This can
happen with the netfilter REJECT target or IPsec tunnels.

Let routing decide the ICMP source address in that case, since the
packet is locally generated there is no inbound interface and
the sysctl should not apply.

The option actually seems to be unfixable broken, on the path
after ip_output() skb->dev points to the outgoing device and
we don't know the incoming device anymore, so its going to do
the absolute wrong thing and pick the address of the outgoing
interface. Add a comment about this.

Reported by Curtis Doty <Curtis@GreenKey.net>.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-05-19 14:44:15 -07:00

1147 lines
28 KiB
C

/*
* NET3: Implementation of the ICMP protocol layer.
*
* Alan Cox, <alan@redhat.com>
*
* Version: $Id: icmp.c,v 1.85 2002/02/01 22:01:03 davem Exp $
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* Some of the function names and the icmp unreach table for this
* module were derived from [icmp.c 1.0.11 06/02/93] by
* Ross Biro, Fred N. van Kempen, Mark Evans, Alan Cox, Gerhard Koerting.
* Other than that this module is a complete rewrite.
*
* Fixes:
* Clemens Fruhwirth : introduce global icmp rate limiting
* with icmp type masking ability instead
* of broken per type icmp timeouts.
* Mike Shaver : RFC1122 checks.
* Alan Cox : Multicast ping reply as self.
* Alan Cox : Fix atomicity lockup in ip_build_xmit
* call.
* Alan Cox : Added 216,128 byte paths to the MTU
* code.
* Martin Mares : RFC1812 checks.
* Martin Mares : Can be configured to follow redirects
* if acting as a router _without_ a
* routing protocol (RFC 1812).
* Martin Mares : Echo requests may be configured to
* be ignored (RFC 1812).
* Martin Mares : Limitation of ICMP error message
* transmit rate (RFC 1812).
* Martin Mares : TOS and Precedence set correctly
* (RFC 1812).
* Martin Mares : Now copying as much data from the
* original packet as we can without
* exceeding 576 bytes (RFC 1812).
* Willy Konynenberg : Transparent proxying support.
* Keith Owens : RFC1191 correction for 4.2BSD based
* path MTU bug.
* Thomas Quinot : ICMP Dest Unreach codes up to 15 are
* valid (RFC 1812).
* Andi Kleen : Check all packet lengths properly
* and moved all kfree_skb() up to
* icmp_rcv.
* Andi Kleen : Move the rate limit bookkeeping
* into the dest entry and use a token
* bucket filter (thanks to ANK). Make
* the rates sysctl configurable.
* Yu Tianli : Fixed two ugly bugs in icmp_send
* - IP option length was accounted wrongly
* - ICMP header length was not accounted
* at all.
* Tristan Greaves : Added sysctl option to ignore bogus
* broadcast responses from broken routers.
*
* To Fix:
*
* - Should use skb_pull() instead of all the manual checking.
* This would also greatly simply some upper layer error handlers. --AK
*
*/
#include <linux/module.h>
#include <linux/types.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/fcntl.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/inet.h>
#include <linux/inetdevice.h>
#include <linux/netdevice.h>
#include <linux/string.h>
#include <linux/netfilter_ipv4.h>
#include <net/snmp.h>
#include <net/ip.h>
#include <net/route.h>
#include <net/protocol.h>
#include <net/icmp.h>
#include <net/tcp.h>
#include <net/udp.h>
#include <net/raw.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <linux/errno.h>
#include <linux/timer.h>
#include <linux/init.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <net/checksum.h>
/*
* Build xmit assembly blocks
*/
struct icmp_bxm {
struct sk_buff *skb;
int offset;
int data_len;
struct {
struct icmphdr icmph;
__be32 times[3];
} data;
int head_len;
struct ip_options replyopts;
unsigned char optbuf[40];
};
/*
* Statistics
*/
DEFINE_SNMP_STAT(struct icmp_mib, icmp_statistics) __read_mostly;
/* An array of errno for error messages from dest unreach. */
/* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */
struct icmp_err icmp_err_convert[] = {
{
.errno = ENETUNREACH, /* ICMP_NET_UNREACH */
.fatal = 0,
},
{
.errno = EHOSTUNREACH, /* ICMP_HOST_UNREACH */
.fatal = 0,
},
{
.errno = ENOPROTOOPT /* ICMP_PROT_UNREACH */,
.fatal = 1,
},
{
.errno = ECONNREFUSED, /* ICMP_PORT_UNREACH */
.fatal = 1,
},
{
.errno = EMSGSIZE, /* ICMP_FRAG_NEEDED */
.fatal = 0,
},
{
.errno = EOPNOTSUPP, /* ICMP_SR_FAILED */
.fatal = 0,
},
{
.errno = ENETUNREACH, /* ICMP_NET_UNKNOWN */
.fatal = 1,
},
{
.errno = EHOSTDOWN, /* ICMP_HOST_UNKNOWN */
.fatal = 1,
},
{
.errno = ENONET, /* ICMP_HOST_ISOLATED */
.fatal = 1,
},
{
.errno = ENETUNREACH, /* ICMP_NET_ANO */
.fatal = 1,
},
{
.errno = EHOSTUNREACH, /* ICMP_HOST_ANO */
.fatal = 1,
},
{
.errno = ENETUNREACH, /* ICMP_NET_UNR_TOS */
.fatal = 0,
},
{
.errno = EHOSTUNREACH, /* ICMP_HOST_UNR_TOS */
.fatal = 0,
},
{
.errno = EHOSTUNREACH, /* ICMP_PKT_FILTERED */
.fatal = 1,
},
{
.errno = EHOSTUNREACH, /* ICMP_PREC_VIOLATION */
.fatal = 1,
},
{
.errno = EHOSTUNREACH, /* ICMP_PREC_CUTOFF */
.fatal = 1,
},
};
/* Control parameters for ECHO replies. */
int sysctl_icmp_echo_ignore_all __read_mostly;
int sysctl_icmp_echo_ignore_broadcasts __read_mostly = 1;
/* Control parameter - ignore bogus broadcast responses? */
int sysctl_icmp_ignore_bogus_error_responses __read_mostly = 1;
/*
* Configurable global rate limit.
*
* ratelimit defines tokens/packet consumed for dst->rate_token bucket
* ratemask defines which icmp types are ratelimited by setting
* it's bit position.
*
* default:
* dest unreachable (3), source quench (4),
* time exceeded (11), parameter problem (12)
*/
int sysctl_icmp_ratelimit __read_mostly = 1 * HZ;
int sysctl_icmp_ratemask __read_mostly = 0x1818;
int sysctl_icmp_errors_use_inbound_ifaddr __read_mostly;
/*
* ICMP control array. This specifies what to do with each ICMP.
*/
struct icmp_control {
int output_entry; /* Field for increment on output */
int input_entry; /* Field for increment on input */
void (*handler)(struct sk_buff *skb);
short error; /* This ICMP is classed as an error message */
};
static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1];
/*
* The ICMP socket(s). This is the most convenient way to flow control
* our ICMP output as well as maintain a clean interface throughout
* all layers. All Socketless IP sends will soon be gone.
*
* On SMP we have one ICMP socket per-cpu.
*/
static DEFINE_PER_CPU(struct socket *, __icmp_socket) = NULL;
#define icmp_socket __get_cpu_var(__icmp_socket)
static __inline__ int icmp_xmit_lock(void)
{
local_bh_disable();
if (unlikely(!spin_trylock(&icmp_socket->sk->sk_lock.slock))) {
/* This can happen if the output path signals a
* dst_link_failure() for an outgoing ICMP packet.
*/
local_bh_enable();
return 1;
}
return 0;
}
static void icmp_xmit_unlock(void)
{
spin_unlock_bh(&icmp_socket->sk->sk_lock.slock);
}
/*
* Send an ICMP frame.
*/
/*
* Check transmit rate limitation for given message.
* The rate information is held in the destination cache now.
* This function is generic and could be used for other purposes
* too. It uses a Token bucket filter as suggested by Alexey Kuznetsov.
*
* Note that the same dst_entry fields are modified by functions in
* route.c too, but these work for packet destinations while xrlim_allow
* works for icmp destinations. This means the rate limiting information
* for one "ip object" is shared - and these ICMPs are twice limited:
* by source and by destination.
*
* RFC 1812: 4.3.2.8 SHOULD be able to limit error message rate
* SHOULD allow setting of rate limits
*
* Shared between ICMPv4 and ICMPv6.
*/
#define XRLIM_BURST_FACTOR 6
int xrlim_allow(struct dst_entry *dst, int timeout)
{
unsigned long now;
int rc = 0;
now = jiffies;
dst->rate_tokens += now - dst->rate_last;
dst->rate_last = now;
if (dst->rate_tokens > XRLIM_BURST_FACTOR * timeout)
dst->rate_tokens = XRLIM_BURST_FACTOR * timeout;
if (dst->rate_tokens >= timeout) {
dst->rate_tokens -= timeout;
rc = 1;
}
return rc;
}
static inline int icmpv4_xrlim_allow(struct rtable *rt, int type, int code)
{
struct dst_entry *dst = &rt->u.dst;
int rc = 1;
if (type > NR_ICMP_TYPES)
goto out;
/* Don't limit PMTU discovery. */
if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
goto out;
/* No rate limit on loopback */
if (dst->dev && (dst->dev->flags&IFF_LOOPBACK))
goto out;
/* Limit if icmp type is enabled in ratemask. */
if ((1 << type) & sysctl_icmp_ratemask)
rc = xrlim_allow(dst, sysctl_icmp_ratelimit);
out:
return rc;
}
/*
* Maintain the counters used in the SNMP statistics for outgoing ICMP
*/
static void icmp_out_count(int type)
{
if (type <= NR_ICMP_TYPES) {
ICMP_INC_STATS(icmp_pointers[type].output_entry);
ICMP_INC_STATS(ICMP_MIB_OUTMSGS);
}
}
/*
* Checksum each fragment, and on the first include the headers and final
* checksum.
*/
static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd,
struct sk_buff *skb)
{
struct icmp_bxm *icmp_param = (struct icmp_bxm *)from;
__wsum csum;
csum = skb_copy_and_csum_bits(icmp_param->skb,
icmp_param->offset + offset,
to, len, 0);
skb->csum = csum_block_add(skb->csum, csum, odd);
if (icmp_pointers[icmp_param->data.icmph.type].error)
nf_ct_attach(skb, icmp_param->skb);
return 0;
}
static void icmp_push_reply(struct icmp_bxm *icmp_param,
struct ipcm_cookie *ipc, struct rtable *rt)
{
struct sk_buff *skb;
if (ip_append_data(icmp_socket->sk, icmp_glue_bits, icmp_param,
icmp_param->data_len+icmp_param->head_len,
icmp_param->head_len,
ipc, rt, MSG_DONTWAIT) < 0)
ip_flush_pending_frames(icmp_socket->sk);
else if ((skb = skb_peek(&icmp_socket->sk->sk_write_queue)) != NULL) {
struct icmphdr *icmph = icmp_hdr(skb);
__wsum csum = 0;
struct sk_buff *skb1;
skb_queue_walk(&icmp_socket->sk->sk_write_queue, skb1) {
csum = csum_add(csum, skb1->csum);
}
csum = csum_partial_copy_nocheck((void *)&icmp_param->data,
(char *)icmph,
icmp_param->head_len, csum);
icmph->checksum = csum_fold(csum);
skb->ip_summed = CHECKSUM_NONE;
ip_push_pending_frames(icmp_socket->sk);
}
}
/*
* Driving logic for building and sending ICMP messages.
*/
static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
{
struct sock *sk = icmp_socket->sk;
struct inet_sock *inet = inet_sk(sk);
struct ipcm_cookie ipc;
struct rtable *rt = (struct rtable *)skb->dst;
__be32 daddr;
if (ip_options_echo(&icmp_param->replyopts, skb))
return;
if (icmp_xmit_lock())
return;
icmp_param->data.icmph.checksum = 0;
icmp_out_count(icmp_param->data.icmph.type);
inet->tos = ip_hdr(skb)->tos;
daddr = ipc.addr = rt->rt_src;
ipc.opt = NULL;
if (icmp_param->replyopts.optlen) {
ipc.opt = &icmp_param->replyopts;
if (ipc.opt->srr)
daddr = icmp_param->replyopts.faddr;
}
{
struct flowi fl = { .nl_u = { .ip4_u =
{ .daddr = daddr,
.saddr = rt->rt_spec_dst,
.tos = RT_TOS(ip_hdr(skb)->tos) } },
.proto = IPPROTO_ICMP };
security_skb_classify_flow(skb, &fl);
if (ip_route_output_key(&rt, &fl))
goto out_unlock;
}
if (icmpv4_xrlim_allow(rt, icmp_param->data.icmph.type,
icmp_param->data.icmph.code))
icmp_push_reply(icmp_param, &ipc, rt);
ip_rt_put(rt);
out_unlock:
icmp_xmit_unlock();
}
/*
* Send an ICMP message in response to a situation
*
* RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header.
* MAY send more (we do).
* MUST NOT change this header information.
* MUST NOT reply to a multicast/broadcast IP address.
* MUST NOT reply to a multicast/broadcast MAC address.
* MUST reply to only the first fragment.
*/
void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
{
struct iphdr *iph;
int room;
struct icmp_bxm icmp_param;
struct rtable *rt = (struct rtable *)skb_in->dst;
struct ipcm_cookie ipc;
__be32 saddr;
u8 tos;
if (!rt)
goto out;
/*
* Find the original header. It is expected to be valid, of course.
* Check this, icmp_send is called from the most obscure devices
* sometimes.
*/
iph = ip_hdr(skb_in);
if ((u8 *)iph < skb_in->head ||
(skb_in->network_header + sizeof(*iph)) > skb_in->tail)
goto out;
/*
* No replies to physical multicast/broadcast
*/
if (skb_in->pkt_type != PACKET_HOST)
goto out;
/*
* Now check at the protocol level
*/
if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
goto out;
/*
* Only reply to fragment 0. We byte re-order the constant
* mask for efficiency.
*/
if (iph->frag_off & htons(IP_OFFSET))
goto out;
/*
* If we send an ICMP error to an ICMP error a mess would result..
*/
if (icmp_pointers[type].error) {
/*
* We are an error, check if we are replying to an
* ICMP error
*/
if (iph->protocol == IPPROTO_ICMP) {
u8 _inner_type, *itp;
itp = skb_header_pointer(skb_in,
skb_network_header(skb_in) +
(iph->ihl << 2) +
offsetof(struct icmphdr,
type) -
skb_in->data,
sizeof(_inner_type),
&_inner_type);
if (itp == NULL)
goto out;
/*
* Assume any unknown ICMP type is an error. This
* isn't specified by the RFC, but think about it..
*/
if (*itp > NR_ICMP_TYPES ||
icmp_pointers[*itp].error)
goto out;
}
}
if (icmp_xmit_lock())
return;
/*
* Construct source address and options.
*/
saddr = iph->daddr;
if (!(rt->rt_flags & RTCF_LOCAL)) {
/* This is broken, skb_in->dev points to the outgoing device
* after the packet passes through ip_output().
*/
if (skb_in->dev && sysctl_icmp_errors_use_inbound_ifaddr)
saddr = inet_select_addr(skb_in->dev, 0, RT_SCOPE_LINK);
else
saddr = 0;
}
tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) |
IPTOS_PREC_INTERNETCONTROL) :
iph->tos;
if (ip_options_echo(&icmp_param.replyopts, skb_in))
goto out_unlock;
/*
* Prepare data for ICMP header.
*/
icmp_param.data.icmph.type = type;
icmp_param.data.icmph.code = code;
icmp_param.data.icmph.un.gateway = info;
icmp_param.data.icmph.checksum = 0;
icmp_param.skb = skb_in;
icmp_param.offset = skb_network_offset(skb_in);
icmp_out_count(icmp_param.data.icmph.type);
inet_sk(icmp_socket->sk)->tos = tos;
ipc.addr = iph->saddr;
ipc.opt = &icmp_param.replyopts;
{
struct flowi fl = {
.nl_u = {
.ip4_u = {
.daddr = icmp_param.replyopts.srr ?
icmp_param.replyopts.faddr :
iph->saddr,
.saddr = saddr,
.tos = RT_TOS(tos)
}
},
.proto = IPPROTO_ICMP,
.uli_u = {
.icmpt = {
.type = type,
.code = code
}
}
};
security_skb_classify_flow(skb_in, &fl);
if (ip_route_output_key(&rt, &fl))
goto out_unlock;
}
if (!icmpv4_xrlim_allow(rt, type, code))
goto ende;
/* RFC says return as much as we can without exceeding 576 bytes. */
room = dst_mtu(&rt->u.dst);
if (room > 576)
room = 576;
room -= sizeof(struct iphdr) + icmp_param.replyopts.optlen;
room -= sizeof(struct icmphdr);
icmp_param.data_len = skb_in->len - icmp_param.offset;
if (icmp_param.data_len > room)
icmp_param.data_len = room;
icmp_param.head_len = sizeof(struct icmphdr);
icmp_push_reply(&icmp_param, &ipc, rt);
ende:
ip_rt_put(rt);
out_unlock:
icmp_xmit_unlock();
out:;
}
/*
* Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEED, and ICMP_QUENCH.
*/
static void icmp_unreach(struct sk_buff *skb)
{
struct iphdr *iph;
struct icmphdr *icmph;
int hash, protocol;
struct net_protocol *ipprot;
struct sock *raw_sk;
u32 info = 0;
/*
* Incomplete header ?
* Only checks for the IP header, there should be an
* additional check for longer headers in upper levels.
*/
if (!pskb_may_pull(skb, sizeof(struct iphdr)))
goto out_err;
icmph = icmp_hdr(skb);
iph = (struct iphdr *)skb->data;
if (iph->ihl < 5) /* Mangled header, drop. */
goto out_err;
if (icmph->type == ICMP_DEST_UNREACH) {
switch (icmph->code & 15) {
case ICMP_NET_UNREACH:
case ICMP_HOST_UNREACH:
case ICMP_PROT_UNREACH:
case ICMP_PORT_UNREACH:
break;
case ICMP_FRAG_NEEDED:
if (ipv4_config.no_pmtu_disc) {
LIMIT_NETDEBUG(KERN_INFO "ICMP: %u.%u.%u.%u: "
"fragmentation needed "
"and DF set.\n",
NIPQUAD(iph->daddr));
} else {
info = ip_rt_frag_needed(iph,
ntohs(icmph->un.frag.mtu));
if (!info)
goto out;
}
break;
case ICMP_SR_FAILED:
LIMIT_NETDEBUG(KERN_INFO "ICMP: %u.%u.%u.%u: Source "
"Route Failed.\n",
NIPQUAD(iph->daddr));
break;
default:
break;
}
if (icmph->code > NR_ICMP_UNREACH)
goto out;
} else if (icmph->type == ICMP_PARAMETERPROB)
info = ntohl(icmph->un.gateway) >> 24;
/*
* Throw it at our lower layers
*
* RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
* header.
* RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
* transport layer.
* RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
* transport layer.
*/
/*
* Check the other end isnt violating RFC 1122. Some routers send
* bogus responses to broadcast frames. If you see this message
* first check your netmask matches at both ends, if it does then
* get the other vendor to fix their kit.
*/
if (!sysctl_icmp_ignore_bogus_error_responses &&
inet_addr_type(iph->daddr) == RTN_BROADCAST) {
if (net_ratelimit())
printk(KERN_WARNING "%u.%u.%u.%u sent an invalid ICMP "
"type %u, code %u "
"error to a broadcast: %u.%u.%u.%u on %s\n",
NIPQUAD(ip_hdr(skb)->saddr),
icmph->type, icmph->code,
NIPQUAD(iph->daddr),
skb->dev->name);
goto out;
}
/* Checkin full IP header plus 8 bytes of protocol to
* avoid additional coding at protocol handlers.
*/
if (!pskb_may_pull(skb, iph->ihl * 4 + 8))
goto out;
iph = (struct iphdr *)skb->data;
protocol = iph->protocol;
/*
* Deliver ICMP message to raw sockets. Pretty useless feature?
*/
/* Note: See raw.c and net/raw.h, RAWV4_HTABLE_SIZE==MAX_INET_PROTOS */
hash = protocol & (MAX_INET_PROTOS - 1);
read_lock(&raw_v4_lock);
if ((raw_sk = sk_head(&raw_v4_htable[hash])) != NULL) {
while ((raw_sk = __raw_v4_lookup(raw_sk, protocol, iph->daddr,
iph->saddr,
skb->dev->ifindex)) != NULL) {
raw_err(raw_sk, skb, info);
raw_sk = sk_next(raw_sk);
iph = (struct iphdr *)skb->data;
}
}
read_unlock(&raw_v4_lock);
rcu_read_lock();
ipprot = rcu_dereference(inet_protos[hash]);
if (ipprot && ipprot->err_handler)
ipprot->err_handler(skb, info);
rcu_read_unlock();
out:
return;
out_err:
ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
goto out;
}
/*
* Handle ICMP_REDIRECT.
*/
static void icmp_redirect(struct sk_buff *skb)
{
struct iphdr *iph;
if (skb->len < sizeof(struct iphdr))
goto out_err;
/*
* Get the copied header of the packet that caused the redirect
*/
if (!pskb_may_pull(skb, sizeof(struct iphdr)))
goto out;
iph = (struct iphdr *)skb->data;
switch (icmp_hdr(skb)->code & 7) {
case ICMP_REDIR_NET:
case ICMP_REDIR_NETTOS:
/*
* As per RFC recommendations now handle it as a host redirect.
*/
case ICMP_REDIR_HOST:
case ICMP_REDIR_HOSTTOS:
ip_rt_redirect(ip_hdr(skb)->saddr, iph->daddr,
icmp_hdr(skb)->un.gateway,
iph->saddr, skb->dev);
break;
}
out:
return;
out_err:
ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
goto out;
}
/*
* Handle ICMP_ECHO ("ping") requests.
*
* RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
* requests.
* RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
* included in the reply.
* RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
* echo requests, MUST have default=NOT.
* See also WRT handling of options once they are done and working.
*/
static void icmp_echo(struct sk_buff *skb)
{
if (!sysctl_icmp_echo_ignore_all) {
struct icmp_bxm icmp_param;
icmp_param.data.icmph = *icmp_hdr(skb);
icmp_param.data.icmph.type = ICMP_ECHOREPLY;
icmp_param.skb = skb;
icmp_param.offset = 0;
icmp_param.data_len = skb->len;
icmp_param.head_len = sizeof(struct icmphdr);
icmp_reply(&icmp_param, skb);
}
}
/*
* Handle ICMP Timestamp requests.
* RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
* SHOULD be in the kernel for minimum random latency.
* MUST be accurate to a few minutes.
* MUST be updated at least at 15Hz.
*/
static void icmp_timestamp(struct sk_buff *skb)
{
struct timeval tv;
struct icmp_bxm icmp_param;
/*
* Too short.
*/
if (skb->len < 4)
goto out_err;
/*
* Fill in the current time as ms since midnight UT:
*/
do_gettimeofday(&tv);
icmp_param.data.times[1] = htonl((tv.tv_sec % 86400) * 1000 +
tv.tv_usec / 1000);
icmp_param.data.times[2] = icmp_param.data.times[1];
if (skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4))
BUG();
icmp_param.data.icmph = *icmp_hdr(skb);
icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
icmp_param.data.icmph.code = 0;
icmp_param.skb = skb;
icmp_param.offset = 0;
icmp_param.data_len = 0;
icmp_param.head_len = sizeof(struct icmphdr) + 12;
icmp_reply(&icmp_param, skb);
out:
return;
out_err:
ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
goto out;
}
/*
* Handle ICMP_ADDRESS_MASK requests. (RFC950)
*
* RFC1122 (3.2.2.9). A host MUST only send replies to
* ADDRESS_MASK requests if it's been configured as an address mask
* agent. Receiving a request doesn't constitute implicit permission to
* act as one. Of course, implementing this correctly requires (SHOULD)
* a way to turn the functionality on and off. Another one for sysctl(),
* I guess. -- MS
*
* RFC1812 (4.3.3.9). A router MUST implement it.
* A router SHOULD have switch turning it on/off.
* This switch MUST be ON by default.
*
* Gratuitous replies, zero-source replies are not implemented,
* that complies with RFC. DO NOT implement them!!! All the idea
* of broadcast addrmask replies as specified in RFC950 is broken.
* The problem is that it is not uncommon to have several prefixes
* on one physical interface. Moreover, addrmask agent can even be
* not aware of existing another prefixes.
* If source is zero, addrmask agent cannot choose correct prefix.
* Gratuitous mask announcements suffer from the same problem.
* RFC1812 explains it, but still allows to use ADDRMASK,
* that is pretty silly. --ANK
*
* All these rules are so bizarre, that I removed kernel addrmask
* support at all. It is wrong, it is obsolete, nobody uses it in
* any case. --ANK
*
* Furthermore you can do it with a usermode address agent program
* anyway...
*/
static void icmp_address(struct sk_buff *skb)
{
#if 0
if (net_ratelimit())
printk(KERN_DEBUG "a guy asks for address mask. Who is it?\n");
#endif
}
/*
* RFC1812 (4.3.3.9). A router SHOULD listen all replies, and complain
* loudly if an inconsistency is found.
*/
static void icmp_address_reply(struct sk_buff *skb)
{
struct rtable *rt = (struct rtable *)skb->dst;
struct net_device *dev = skb->dev;
struct in_device *in_dev;
struct in_ifaddr *ifa;
if (skb->len < 4 || !(rt->rt_flags&RTCF_DIRECTSRC))
goto out;
in_dev = in_dev_get(dev);
if (!in_dev)
goto out;
rcu_read_lock();
if (in_dev->ifa_list &&
IN_DEV_LOG_MARTIANS(in_dev) &&
IN_DEV_FORWARD(in_dev)) {
__be32 _mask, *mp;
mp = skb_header_pointer(skb, 0, sizeof(_mask), &_mask);
BUG_ON(mp == NULL);
for (ifa = in_dev->ifa_list; ifa; ifa = ifa->ifa_next) {
if (*mp == ifa->ifa_mask &&
inet_ifa_match(rt->rt_src, ifa))
break;
}
if (!ifa && net_ratelimit()) {
printk(KERN_INFO "Wrong address mask %u.%u.%u.%u from "
"%s/%u.%u.%u.%u\n",
NIPQUAD(*mp), dev->name, NIPQUAD(rt->rt_src));
}
}
rcu_read_unlock();
in_dev_put(in_dev);
out:;
}
static void icmp_discard(struct sk_buff *skb)
{
}
/*
* Deal with incoming ICMP packets.
*/
int icmp_rcv(struct sk_buff *skb)
{
struct icmphdr *icmph;
struct rtable *rt = (struct rtable *)skb->dst;
ICMP_INC_STATS_BH(ICMP_MIB_INMSGS);
switch (skb->ip_summed) {
case CHECKSUM_COMPLETE:
if (!csum_fold(skb->csum))
break;
/* fall through */
case CHECKSUM_NONE:
skb->csum = 0;
if (__skb_checksum_complete(skb))
goto error;
}
if (!pskb_pull(skb, sizeof(struct icmphdr)))
goto error;
icmph = icmp_hdr(skb);
/*
* 18 is the highest 'known' ICMP type. Anything else is a mystery
*
* RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently
* discarded.
*/
if (icmph->type > NR_ICMP_TYPES)
goto error;
/*
* Parse the ICMP message
*/
if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
/*
* RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
* silently ignored (we let user decide with a sysctl).
* RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
* discarded if to broadcast/multicast.
*/
if ((icmph->type == ICMP_ECHO ||
icmph->type == ICMP_TIMESTAMP) &&
sysctl_icmp_echo_ignore_broadcasts) {
goto error;
}
if (icmph->type != ICMP_ECHO &&
icmph->type != ICMP_TIMESTAMP &&
icmph->type != ICMP_ADDRESS &&
icmph->type != ICMP_ADDRESSREPLY) {
goto error;
}
}
ICMP_INC_STATS_BH(icmp_pointers[icmph->type].input_entry);
icmp_pointers[icmph->type].handler(skb);
drop:
kfree_skb(skb);
return 0;
error:
ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
goto drop;
}
/*
* This table is the definition of how we handle ICMP.
*/
static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
[ICMP_ECHOREPLY] = {
.output_entry = ICMP_MIB_OUTECHOREPS,
.input_entry = ICMP_MIB_INECHOREPS,
.handler = icmp_discard,
},
[1] = {
.output_entry = ICMP_MIB_DUMMY,
.input_entry = ICMP_MIB_INERRORS,
.handler = icmp_discard,
.error = 1,
},
[2] = {
.output_entry = ICMP_MIB_DUMMY,
.input_entry = ICMP_MIB_INERRORS,
.handler = icmp_discard,
.error = 1,
},
[ICMP_DEST_UNREACH] = {
.output_entry = ICMP_MIB_OUTDESTUNREACHS,
.input_entry = ICMP_MIB_INDESTUNREACHS,
.handler = icmp_unreach,
.error = 1,
},
[ICMP_SOURCE_QUENCH] = {
.output_entry = ICMP_MIB_OUTSRCQUENCHS,
.input_entry = ICMP_MIB_INSRCQUENCHS,
.handler = icmp_unreach,
.error = 1,
},
[ICMP_REDIRECT] = {
.output_entry = ICMP_MIB_OUTREDIRECTS,
.input_entry = ICMP_MIB_INREDIRECTS,
.handler = icmp_redirect,
.error = 1,
},
[6] = {
.output_entry = ICMP_MIB_DUMMY,
.input_entry = ICMP_MIB_INERRORS,
.handler = icmp_discard,
.error = 1,
},
[7] = {
.output_entry = ICMP_MIB_DUMMY,
.input_entry = ICMP_MIB_INERRORS,
.handler = icmp_discard,
.error = 1,
},
[ICMP_ECHO] = {
.output_entry = ICMP_MIB_OUTECHOS,
.input_entry = ICMP_MIB_INECHOS,
.handler = icmp_echo,
},
[9] = {
.output_entry = ICMP_MIB_DUMMY,
.input_entry = ICMP_MIB_INERRORS,
.handler = icmp_discard,
.error = 1,
},
[10] = {
.output_entry = ICMP_MIB_DUMMY,
.input_entry = ICMP_MIB_INERRORS,
.handler = icmp_discard,
.error = 1,
},
[ICMP_TIME_EXCEEDED] = {
.output_entry = ICMP_MIB_OUTTIMEEXCDS,
.input_entry = ICMP_MIB_INTIMEEXCDS,
.handler = icmp_unreach,
.error = 1,
},
[ICMP_PARAMETERPROB] = {
.output_entry = ICMP_MIB_OUTPARMPROBS,
.input_entry = ICMP_MIB_INPARMPROBS,
.handler = icmp_unreach,
.error = 1,
},
[ICMP_TIMESTAMP] = {
.output_entry = ICMP_MIB_OUTTIMESTAMPS,
.input_entry = ICMP_MIB_INTIMESTAMPS,
.handler = icmp_timestamp,
},
[ICMP_TIMESTAMPREPLY] = {
.output_entry = ICMP_MIB_OUTTIMESTAMPREPS,
.input_entry = ICMP_MIB_INTIMESTAMPREPS,
.handler = icmp_discard,
},
[ICMP_INFO_REQUEST] = {
.output_entry = ICMP_MIB_DUMMY,
.input_entry = ICMP_MIB_DUMMY,
.handler = icmp_discard,
},
[ICMP_INFO_REPLY] = {
.output_entry = ICMP_MIB_DUMMY,
.input_entry = ICMP_MIB_DUMMY,
.handler = icmp_discard,
},
[ICMP_ADDRESS] = {
.output_entry = ICMP_MIB_OUTADDRMASKS,
.input_entry = ICMP_MIB_INADDRMASKS,
.handler = icmp_address,
},
[ICMP_ADDRESSREPLY] = {
.output_entry = ICMP_MIB_OUTADDRMASKREPS,
.input_entry = ICMP_MIB_INADDRMASKREPS,
.handler = icmp_address_reply,
},
};
void __init icmp_init(struct net_proto_family *ops)
{
struct inet_sock *inet;
int i;
for_each_possible_cpu(i) {
int err;
err = sock_create_kern(PF_INET, SOCK_RAW, IPPROTO_ICMP,
&per_cpu(__icmp_socket, i));
if (err < 0)
panic("Failed to create the ICMP control socket.\n");
per_cpu(__icmp_socket, i)->sk->sk_allocation = GFP_ATOMIC;
/* Enough space for 2 64K ICMP packets, including
* sk_buff struct overhead.
*/
per_cpu(__icmp_socket, i)->sk->sk_sndbuf =
(2 * ((64 * 1024) + sizeof(struct sk_buff)));
inet = inet_sk(per_cpu(__icmp_socket, i)->sk);
inet->uc_ttl = -1;
inet->pmtudisc = IP_PMTUDISC_DONT;
/* Unhash it so that IP input processing does not even
* see it, we do not wish this socket to see incoming
* packets.
*/
per_cpu(__icmp_socket, i)->sk->sk_prot->unhash(per_cpu(__icmp_socket, i)->sk);
}
}
EXPORT_SYMBOL(icmp_err_convert);
EXPORT_SYMBOL(icmp_send);
EXPORT_SYMBOL(icmp_statistics);
EXPORT_SYMBOL(xrlim_allow);