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Diffstat (limited to 'net/ipv4/icmp.c')
-rw-r--r--net/ipv4/icmp.c1143
1 files changed, 1143 insertions, 0 deletions
diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
new file mode 100644
index 00000000000..85bf0d3e294
--- /dev/null
+++ b/net/ipv4/icmp.c
@@ -0,0 +1,1143 @@
+/*
+ * NET3: Implementation of the ICMP protocol layer.
+ *
+ * Alan Cox, <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/config.h>
+#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/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;
+ __u32 times[3];
+ } data;
+ int head_len;
+ struct ip_options replyopts;
+ unsigned char optbuf[40];
+};
+
+/*
+ * Statistics
+ */
+DEFINE_SNMP_STAT(struct icmp_mib, icmp_statistics);
+
+/* An array of errno for error messages from dest unreach. */
+/* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */
+
+struct icmp_err icmp_err_convert[] = {
+ {
+ .errno = ENETUNREACH, /* ICMP_NET_UNREACH */
+ .fatal = 0,
+ },
+ {
+ .errno = EHOSTUNREACH, /* ICMP_HOST_UNREACH */
+ .fatal = 0,
+ },
+ {
+ .errno = ENOPROTOOPT /* ICMP_PROT_UNREACH */,
+ .fatal = 1,
+ },
+ {
+ .errno = ECONNREFUSED, /* ICMP_PORT_UNREACH */
+ .fatal = 1,
+ },
+ {
+ .errno = EMSGSIZE, /* ICMP_FRAG_NEEDED */
+ .fatal = 0,
+ },
+ {
+ .errno = EOPNOTSUPP, /* ICMP_SR_FAILED */
+ .fatal = 0,
+ },
+ {
+ .errno = ENETUNREACH, /* ICMP_NET_UNKNOWN */
+ .fatal = 1,
+ },
+ {
+ .errno = EHOSTDOWN, /* ICMP_HOST_UNKNOWN */
+ .fatal = 1,
+ },
+ {
+ .errno = ENONET, /* ICMP_HOST_ISOLATED */
+ .fatal = 1,
+ },
+ {
+ .errno = ENETUNREACH, /* ICMP_NET_ANO */
+ .fatal = 1,
+ },
+ {
+ .errno = EHOSTUNREACH, /* ICMP_HOST_ANO */
+ .fatal = 1,
+ },
+ {
+ .errno = ENETUNREACH, /* ICMP_NET_UNR_TOS */
+ .fatal = 0,
+ },
+ {
+ .errno = EHOSTUNREACH, /* ICMP_HOST_UNR_TOS */
+ .fatal = 0,
+ },
+ {
+ .errno = EHOSTUNREACH, /* ICMP_PKT_FILTERED */
+ .fatal = 1,
+ },
+ {
+ .errno = EHOSTUNREACH, /* ICMP_PREC_VIOLATION */
+ .fatal = 1,
+ },
+ {
+ .errno = EHOSTUNREACH, /* ICMP_PREC_CUTOFF */
+ .fatal = 1,
+ },
+};
+
+/* Control parameters for ECHO replies. */
+int sysctl_icmp_echo_ignore_all;
+int sysctl_icmp_echo_ignore_broadcasts;
+
+/* Control parameter - ignore bogus broadcast responses? */
+int sysctl_icmp_ignore_bogus_error_responses;
+
+/*
+ * Configurable global rate limit.
+ *
+ * ratelimit defines tokens/packet consumed for dst->rate_token bucket
+ * ratemask defines which icmp types are ratelimited by setting
+ * it's bit position.
+ *
+ * default:
+ * dest unreachable (3), source quench (4),
+ * time exceeded (11), parameter problem (12)
+ */
+
+int sysctl_icmp_ratelimit = 1 * HZ;
+int sysctl_icmp_ratemask = 0x1818;
+
+/*
+ * ICMP control array. This specifies what to do with each ICMP.
+ */
+
+struct icmp_control {
+ int output_entry; /* Field for increment on output */
+ int input_entry; /* Field for increment on input */
+ void (*handler)(struct sk_buff *skb);
+ short error; /* This ICMP is classed as an error message */
+};
+
+static struct icmp_control icmp_pointers[NR_ICMP_TYPES+1];
+
+/*
+ * The ICMP socket(s). This is the most convenient way to flow control
+ * our ICMP output as well as maintain a clean interface throughout
+ * all layers. All Socketless IP sends will soon be gone.
+ *
+ * On SMP we have one ICMP socket per-cpu.
+ */
+static DEFINE_PER_CPU(struct socket *, __icmp_socket) = NULL;
+#define icmp_socket __get_cpu_var(__icmp_socket)
+
+static __inline__ int icmp_xmit_lock(void)
+{
+ local_bh_disable();
+
+ if (unlikely(!spin_trylock(&icmp_socket->sk->sk_lock.slock))) {
+ /* This can happen if the output path signals a
+ * dst_link_failure() for an outgoing ICMP packet.
+ */
+ local_bh_enable();
+ return 1;
+ }
+ return 0;
+}
+
+static void icmp_xmit_unlock(void)
+{
+ spin_unlock_bh(&icmp_socket->sk->sk_lock.slock);
+}
+
+/*
+ * Send an ICMP frame.
+ */
+
+/*
+ * Check transmit rate limitation for given message.
+ * The rate information is held in the destination cache now.
+ * This function is generic and could be used for other purposes
+ * too. It uses a Token bucket filter as suggested by Alexey Kuznetsov.
+ *
+ * Note that the same dst_entry fields are modified by functions in
+ * route.c too, but these work for packet destinations while xrlim_allow
+ * works for icmp destinations. This means the rate limiting information
+ * for one "ip object" is shared - and these ICMPs are twice limited:
+ * by source and by destination.
+ *
+ * RFC 1812: 4.3.2.8 SHOULD be able to limit error message rate
+ * SHOULD allow setting of rate limits
+ *
+ * Shared between ICMPv4 and ICMPv6.
+ */
+#define XRLIM_BURST_FACTOR 6
+int xrlim_allow(struct dst_entry *dst, int timeout)
+{
+ unsigned long now;
+ int rc = 0;
+
+ now = jiffies;
+ dst->rate_tokens += now - dst->rate_last;
+ dst->rate_last = now;
+ if (dst->rate_tokens > XRLIM_BURST_FACTOR * timeout)
+ dst->rate_tokens = XRLIM_BURST_FACTOR * timeout;
+ if (dst->rate_tokens >= timeout) {
+ dst->rate_tokens -= timeout;
+ rc = 1;
+ }
+ return rc;
+}
+
+static inline int icmpv4_xrlim_allow(struct rtable *rt, int type, int code)
+{
+ struct dst_entry *dst = &rt->u.dst;
+ int rc = 1;
+
+ if (type > NR_ICMP_TYPES)
+ goto out;
+
+ /* Don't limit PMTU discovery. */
+ if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
+ goto out;
+
+ /* No rate limit on loopback */
+ if (dst->dev && (dst->dev->flags&IFF_LOOPBACK))
+ goto out;
+
+ /* Limit if icmp type is enabled in ratemask. */
+ if ((1 << type) & sysctl_icmp_ratemask)
+ rc = xrlim_allow(dst, sysctl_icmp_ratelimit);
+out:
+ return rc;
+}
+
+/*
+ * Maintain the counters used in the SNMP statistics for outgoing ICMP
+ */
+static void icmp_out_count(int type)
+{
+ if (type <= NR_ICMP_TYPES) {
+ ICMP_INC_STATS(icmp_pointers[type].output_entry);
+ ICMP_INC_STATS(ICMP_MIB_OUTMSGS);
+ }
+}
+
+/*
+ * Checksum each fragment, and on the first include the headers and final
+ * checksum.
+ */
+static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd,
+ struct sk_buff *skb)
+{
+ struct icmp_bxm *icmp_param = (struct icmp_bxm *)from;
+ unsigned int csum;
+
+ csum = skb_copy_and_csum_bits(icmp_param->skb,
+ icmp_param->offset + offset,
+ to, len, 0);
+
+ skb->csum = csum_block_add(skb->csum, csum, odd);
+ if (icmp_pointers[icmp_param->data.icmph.type].error)
+ nf_ct_attach(skb, icmp_param->skb);
+ return 0;
+}
+
+static void icmp_push_reply(struct icmp_bxm *icmp_param,
+ struct ipcm_cookie *ipc, struct rtable *rt)
+{
+ struct sk_buff *skb;
+
+ ip_append_data(icmp_socket->sk, icmp_glue_bits, icmp_param,
+ icmp_param->data_len+icmp_param->head_len,
+ icmp_param->head_len,
+ ipc, rt, MSG_DONTWAIT);
+
+ if ((skb = skb_peek(&icmp_socket->sk->sk_write_queue)) != NULL) {
+ struct icmphdr *icmph = skb->h.icmph;
+ unsigned int csum = 0;
+ struct sk_buff *skb1;
+
+ skb_queue_walk(&icmp_socket->sk->sk_write_queue, skb1) {
+ csum = csum_add(csum, skb1->csum);
+ }
+ csum = csum_partial_copy_nocheck((void *)&icmp_param->data,
+ (char *)icmph,
+ icmp_param->head_len, csum);
+ icmph->checksum = csum_fold(csum);
+ skb->ip_summed = CHECKSUM_NONE;
+ ip_push_pending_frames(icmp_socket->sk);
+ }
+}
+
+/*
+ * Driving logic for building and sending ICMP messages.
+ */
+
+static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
+{
+ struct sock *sk = icmp_socket->sk;
+ struct inet_sock *inet = inet_sk(sk);
+ struct ipcm_cookie ipc;
+ struct rtable *rt = (struct rtable *)skb->dst;
+ u32 daddr;
+
+ if (ip_options_echo(&icmp_param->replyopts, skb))
+ goto out;
+
+ if (icmp_xmit_lock())
+ return;
+
+ icmp_param->data.icmph.checksum = 0;
+ icmp_out_count(icmp_param->data.icmph.type);
+
+ inet->tos = skb->nh.iph->tos;
+ daddr = ipc.addr = rt->rt_src;
+ ipc.opt = NULL;
+ if (icmp_param->replyopts.optlen) {
+ ipc.opt = &icmp_param->replyopts;
+ if (ipc.opt->srr)
+ daddr = icmp_param->replyopts.faddr;
+ }
+ {
+ struct flowi fl = { .nl_u = { .ip4_u =
+ { .daddr = daddr,
+ .saddr = rt->rt_spec_dst,
+ .tos = RT_TOS(skb->nh.iph->tos) } },
+ .proto = IPPROTO_ICMP };
+ if (ip_route_output_key(&rt, &fl))
+ goto out_unlock;
+ }
+ if (icmpv4_xrlim_allow(rt, icmp_param->data.icmph.type,
+ icmp_param->data.icmph.code))
+ icmp_push_reply(icmp_param, &ipc, rt);
+ ip_rt_put(rt);
+out_unlock:
+ icmp_xmit_unlock();
+out:;
+}
+
+
+/*
+ * Send an ICMP message in response to a situation
+ *
+ * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header.
+ * MAY send more (we do).
+ * MUST NOT change this header information.
+ * MUST NOT reply to a multicast/broadcast IP address.
+ * MUST NOT reply to a multicast/broadcast MAC address.
+ * MUST reply to only the first fragment.
+ */
+
+void icmp_send(struct sk_buff *skb_in, int type, int code, u32 info)
+{
+ struct iphdr *iph;
+ int room;
+ struct icmp_bxm icmp_param;
+ struct rtable *rt = (struct rtable *)skb_in->dst;
+ struct ipcm_cookie ipc;
+ u32 saddr;
+ u8 tos;
+
+ if (!rt)
+ goto out;
+
+ /*
+ * Find the original header. It is expected to be valid, of course.
+ * Check this, icmp_send is called from the most obscure devices
+ * sometimes.
+ */
+ iph = skb_in->nh.iph;
+
+ if ((u8 *)iph < skb_in->head || (u8 *)(iph + 1) > skb_in->tail)
+ goto out;
+
+ /*
+ * No replies to physical multicast/broadcast
+ */
+ if (skb_in->pkt_type != PACKET_HOST)
+ goto out;
+
+ /*
+ * Now check at the protocol level
+ */
+ if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
+ goto out;
+
+ /*
+ * Only reply to fragment 0. We byte re-order the constant
+ * mask for efficiency.
+ */
+ if (iph->frag_off & htons(IP_OFFSET))
+ goto out;
+
+ /*
+ * If we send an ICMP error to an ICMP error a mess would result..
+ */
+ if (icmp_pointers[type].error) {
+ /*
+ * We are an error, check if we are replying to an
+ * ICMP error
+ */
+ if (iph->protocol == IPPROTO_ICMP) {
+ u8 _inner_type, *itp;
+
+ itp = skb_header_pointer(skb_in,
+ skb_in->nh.raw +
+ (iph->ihl << 2) +
+ offsetof(struct icmphdr,
+ type) -
+ skb_in->data,
+ sizeof(_inner_type),
+ &_inner_type);
+ if (itp == NULL)
+ goto out;
+
+ /*
+ * Assume any unknown ICMP type is an error. This
+ * isn't specified by the RFC, but think about it..
+ */
+ if (*itp > NR_ICMP_TYPES ||
+ icmp_pointers[*itp].error)
+ goto out;
+ }
+ }
+
+ if (icmp_xmit_lock())
+ return;
+
+ /*
+ * Construct source address and options.
+ */
+
+ saddr = iph->daddr;
+ if (!(rt->rt_flags & RTCF_LOCAL))
+ saddr = 0;
+
+ tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) |
+ IPTOS_PREC_INTERNETCONTROL) :
+ iph->tos;
+
+ if (ip_options_echo(&icmp_param.replyopts, skb_in))
+ goto ende;
+
+
+ /*
+ * Prepare data for ICMP header.
+ */
+
+ icmp_param.data.icmph.type = type;
+ icmp_param.data.icmph.code = code;
+ icmp_param.data.icmph.un.gateway = info;
+ icmp_param.data.icmph.checksum = 0;
+ icmp_param.skb = skb_in;
+ icmp_param.offset = skb_in->nh.raw - skb_in->data;
+ icmp_out_count(icmp_param.data.icmph.type);
+ inet_sk(icmp_socket->sk)->tos = tos;
+ ipc.addr = iph->saddr;
+ ipc.opt = &icmp_param.replyopts;
+
+ {
+ struct flowi fl = {
+ .nl_u = {
+ .ip4_u = {
+ .daddr = icmp_param.replyopts.srr ?
+ icmp_param.replyopts.faddr :
+ iph->saddr,
+ .saddr = saddr,
+ .tos = RT_TOS(tos)
+ }
+ },
+ .proto = IPPROTO_ICMP,
+ .uli_u = {
+ .icmpt = {
+ .type = type,
+ .code = code
+ }
+ }
+ };
+ if (ip_route_output_key(&rt, &fl))
+ goto out_unlock;
+ }
+
+ if (!icmpv4_xrlim_allow(rt, type, code))
+ goto ende;
+
+ /* RFC says return as much as we can without exceeding 576 bytes. */
+
+ room = dst_mtu(&rt->u.dst);
+ if (room > 576)
+ room = 576;
+ room -= sizeof(struct iphdr) + icmp_param.replyopts.optlen;
+ room -= sizeof(struct icmphdr);
+
+ icmp_param.data_len = skb_in->len - icmp_param.offset;
+ if (icmp_param.data_len > room)
+ icmp_param.data_len = room;
+ icmp_param.head_len = sizeof(struct icmphdr);
+
+ icmp_push_reply(&icmp_param, &ipc, rt);
+ende:
+ ip_rt_put(rt);
+out_unlock:
+ icmp_xmit_unlock();
+out:;
+}
+
+
+/*
+ * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEED, and ICMP_QUENCH.
+ */
+
+static void icmp_unreach(struct sk_buff *skb)
+{
+ struct iphdr *iph;
+ struct icmphdr *icmph;
+ int hash, protocol;
+ struct net_protocol *ipprot;
+ struct sock *raw_sk;
+ u32 info = 0;
+
+ /*
+ * Incomplete header ?
+ * Only checks for the IP header, there should be an
+ * additional check for longer headers in upper levels.
+ */
+
+ if (!pskb_may_pull(skb, sizeof(struct iphdr)))
+ goto out_err;
+
+ icmph = skb->h.icmph;
+ iph = (struct iphdr *)skb->data;
+
+ if (iph->ihl < 5) /* Mangled header, drop. */
+ goto out_err;
+
+ if (icmph->type == ICMP_DEST_UNREACH) {
+ switch (icmph->code & 15) {
+ case ICMP_NET_UNREACH:
+ case ICMP_HOST_UNREACH:
+ case ICMP_PROT_UNREACH:
+ case ICMP_PORT_UNREACH:
+ break;
+ case ICMP_FRAG_NEEDED:
+ if (ipv4_config.no_pmtu_disc) {
+ LIMIT_NETDEBUG(
+ printk(KERN_INFO "ICMP: %u.%u.%u.%u: "
+ "fragmentation needed "
+ "and DF set.\n",
+ NIPQUAD(iph->daddr)));
+ } else {
+ info = ip_rt_frag_needed(iph,
+ ntohs(icmph->un.frag.mtu));
+ if (!info)
+ goto out;
+ }
+ break;
+ case ICMP_SR_FAILED:
+ LIMIT_NETDEBUG(
+ printk(KERN_INFO "ICMP: %u.%u.%u.%u: Source "
+ "Route Failed.\n",
+ NIPQUAD(iph->daddr)));
+ break;
+ default:
+ break;
+ }
+ if (icmph->code > NR_ICMP_UNREACH)
+ goto out;
+ } else if (icmph->type == ICMP_PARAMETERPROB)
+ info = ntohl(icmph->un.gateway) >> 24;
+
+ /*
+ * Throw it at our lower layers
+ *
+ * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
+ * header.
+ * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
+ * transport layer.
+ * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
+ * transport layer.
+ */
+
+ /*
+ * Check the other end isnt violating RFC 1122. Some routers send
+ * bogus responses to broadcast frames. If you see this message
+ * first check your netmask matches at both ends, if it does then
+ * get the other vendor to fix their kit.
+ */
+
+ if (!sysctl_icmp_ignore_bogus_error_responses &&
+ inet_addr_type(iph->daddr) == RTN_BROADCAST) {
+ if (net_ratelimit())
+ printk(KERN_WARNING "%u.%u.%u.%u sent an invalid ICMP "
+ "type %u, code %u "
+ "error to a broadcast: %u.%u.%u.%u on %s\n",
+ NIPQUAD(skb->nh.iph->saddr),
+ icmph->type, icmph->code,
+ NIPQUAD(iph->daddr),
+ skb->dev->name);
+ goto out;
+ }
+
+ /* Checkin full IP header plus 8 bytes of protocol to
+ * avoid additional coding at protocol handlers.
+ */
+ if (!pskb_may_pull(skb, iph->ihl * 4 + 8))
+ goto out;
+
+ iph = (struct iphdr *)skb->data;
+ protocol = iph->protocol;
+
+ /*
+ * Deliver ICMP message to raw sockets. Pretty useless feature?
+ */
+
+ /* Note: See raw.c and net/raw.h, RAWV4_HTABLE_SIZE==MAX_INET_PROTOS */
+ hash = protocol & (MAX_INET_PROTOS - 1);
+ read_lock(&raw_v4_lock);
+ if ((raw_sk = sk_head(&raw_v4_htable[hash])) != NULL) {
+ while ((raw_sk = __raw_v4_lookup(raw_sk, protocol, iph->daddr,
+ iph->saddr,
+ skb->dev->ifindex)) != NULL) {
+ raw_err(raw_sk, skb, info);
+ raw_sk = sk_next(raw_sk);
+ iph = (struct iphdr *)skb->data;
+ }
+ }
+ read_unlock(&raw_v4_lock);
+
+ rcu_read_lock();
+ ipprot = rcu_dereference(inet_protos[hash]);
+ if (ipprot && ipprot->err_handler)
+ ipprot->err_handler(skb, info);
+ rcu_read_unlock();
+
+out:
+ return;
+out_err:
+ ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
+ goto out;
+}
+
+
+/*
+ * Handle ICMP_REDIRECT.
+ */
+
+static void icmp_redirect(struct sk_buff *skb)
+{
+ struct iphdr *iph;
+ unsigned long ip;
+
+ if (skb->len < sizeof(struct iphdr))
+ goto out_err;
+
+ /*
+ * Get the copied header of the packet that caused the redirect
+ */
+ if (!pskb_may_pull(skb, sizeof(struct iphdr)))
+ goto out;
+
+ iph = (struct iphdr *)skb->data;
+ ip = iph->daddr;
+
+ switch (skb->h.icmph->code & 7) {
+ case ICMP_REDIR_NET:
+ case ICMP_REDIR_NETTOS:
+ /*
+ * As per RFC recommendations now handle it as a host redirect.
+ */
+ case ICMP_REDIR_HOST:
+ case ICMP_REDIR_HOSTTOS:
+ ip_rt_redirect(skb->nh.iph->saddr, ip, skb->h.icmph->un.gateway,
+ iph->saddr, iph->tos, skb->dev);
+ break;
+ }
+out:
+ return;
+out_err:
+ ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
+ goto out;
+}
+
+/*
+ * Handle ICMP_ECHO ("ping") requests.
+ *
+ * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
+ * requests.
+ * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
+ * included in the reply.
+ * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
+ * echo requests, MUST have default=NOT.
+ * See also WRT handling of options once they are done and working.
+ */
+
+static void icmp_echo(struct sk_buff *skb)
+{
+ if (!sysctl_icmp_echo_ignore_all) {
+ struct icmp_bxm icmp_param;
+
+ icmp_param.data.icmph = *skb->h.icmph;
+ icmp_param.data.icmph.type = ICMP_ECHOREPLY;
+ icmp_param.skb = skb;
+ icmp_param.offset = 0;
+ icmp_param.data_len = skb->len;
+ icmp_param.head_len = sizeof(struct icmphdr);
+ icmp_reply(&icmp_param, skb);
+ }
+}
+
+/*
+ * Handle ICMP Timestamp requests.
+ * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
+ * SHOULD be in the kernel for minimum random latency.
+ * MUST be accurate to a few minutes.
+ * MUST be updated at least at 15Hz.
+ */
+static void icmp_timestamp(struct sk_buff *skb)
+{
+ struct timeval tv;
+ struct icmp_bxm icmp_param;
+ /*
+ * Too short.
+ */
+ if (skb->len < 4)
+ goto out_err;
+
+ /*
+ * Fill in the current time as ms since midnight UT:
+ */
+ do_gettimeofday(&tv);
+ icmp_param.data.times[1] = htonl((tv.tv_sec % 86400) * 1000 +
+ tv.tv_usec / 1000);
+ icmp_param.data.times[2] = icmp_param.data.times[1];
+ if (skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4))
+ BUG();
+ icmp_param.data.icmph = *skb->h.icmph;
+ icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
+ icmp_param.data.icmph.code = 0;
+ icmp_param.skb = skb;
+ icmp_param.offset = 0;
+ icmp_param.data_len = 0;
+ icmp_param.head_len = sizeof(struct icmphdr) + 12;
+ icmp_reply(&icmp_param, skb);
+out:
+ return;
+out_err:
+ ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
+ goto out;
+}
+
+
+/*
+ * Handle ICMP_ADDRESS_MASK requests. (RFC950)
+ *
+ * RFC1122 (3.2.2.9). A host MUST only send replies to
+ * ADDRESS_MASK requests if it's been configured as an address mask
+ * agent. Receiving a request doesn't constitute implicit permission to
+ * act as one. Of course, implementing this correctly requires (SHOULD)
+ * a way to turn the functionality on and off. Another one for sysctl(),
+ * I guess. -- MS
+ *
+ * RFC1812 (4.3.3.9). A router MUST implement it.
+ * A router SHOULD have switch turning it on/off.
+ * This switch MUST be ON by default.
+ *
+ * Gratuitous replies, zero-source replies are not implemented,
+ * that complies with RFC. DO NOT implement them!!! All the idea
+ * of broadcast addrmask replies as specified in RFC950 is broken.
+ * The problem is that it is not uncommon to have several prefixes
+ * on one physical interface. Moreover, addrmask agent can even be
+ * not aware of existing another prefixes.
+ * If source is zero, addrmask agent cannot choose correct prefix.
+ * Gratuitous mask announcements suffer from the same problem.
+ * RFC1812 explains it, but still allows to use ADDRMASK,
+ * that is pretty silly. --ANK
+ *
+ * All these rules are so bizarre, that I removed kernel addrmask
+ * support at all. It is wrong, it is obsolete, nobody uses it in
+ * any case. --ANK
+ *
+ * Furthermore you can do it with a usermode address agent program
+ * anyway...
+ */
+
+static void icmp_address(struct sk_buff *skb)
+{
+#if 0
+ if (net_ratelimit())
+ printk(KERN_DEBUG "a guy asks for address mask. Who is it?\n");
+#endif
+}
+
+/*
+ * RFC1812 (4.3.3.9). A router SHOULD listen all replies, and complain
+ * loudly if an inconsistency is found.
+ */
+
+static void icmp_address_reply(struct sk_buff *skb)
+{
+ struct rtable *rt = (struct rtable *)skb->dst;
+ struct net_device *dev = skb->dev;
+ struct in_device *in_dev;
+ struct in_ifaddr *ifa;
+
+ if (skb->len < 4 || !(rt->rt_flags&RTCF_DIRECTSRC))
+ goto out;
+
+ in_dev = in_dev_get(dev);
+ if (!in_dev)
+ goto out;
+ rcu_read_lock();
+ if (in_dev->ifa_list &&
+ IN_DEV_LOG_MARTIANS(in_dev) &&
+ IN_DEV_FORWARD(in_dev)) {
+ u32 _mask, *mp;
+
+ mp = skb_header_pointer(skb, 0, sizeof(_mask), &_mask);
+ if (mp == NULL)
+ BUG();
+ for (ifa = in_dev->ifa_list; ifa; ifa = ifa->ifa_next) {
+ if (*mp == ifa->ifa_mask &&
+ inet_ifa_match(rt->rt_src, ifa))
+ break;
+ }
+ if (!ifa && net_ratelimit()) {
+ printk(KERN_INFO "Wrong address mask %u.%u.%u.%u from "
+ "%s/%u.%u.%u.%u\n",
+ NIPQUAD(*mp), dev->name, NIPQUAD(rt->rt_src));
+ }
+ }
+ rcu_read_unlock();
+ in_dev_put(in_dev);
+out:;
+}
+
+static void icmp_discard(struct sk_buff *skb)
+{
+}
+
+/*
+ * Deal with incoming ICMP packets.
+ */
+int icmp_rcv(struct sk_buff *skb)
+{
+ struct icmphdr *icmph;
+ struct rtable *rt = (struct rtable *)skb->dst;
+
+ ICMP_INC_STATS_BH(ICMP_MIB_INMSGS);
+
+ switch (skb->ip_summed) {
+ case CHECKSUM_HW:
+ if (!(u16)csum_fold(skb->csum))
+ break;
+ NETDEBUG(if (net_ratelimit())
+ printk(KERN_DEBUG "icmp v4 hw csum failure\n"));
+ case CHECKSUM_NONE:
+ if ((u16)csum_fold(skb_checksum(skb, 0, skb->len, 0)))
+ goto error;
+ default:;
+ }
+
+ if (!pskb_pull(skb, sizeof(struct icmphdr)))
+ goto error;
+
+ icmph = skb->h.icmph;
+
+ /*
+ * 18 is the highest 'known' ICMP type. Anything else is a mystery
+ *
+ * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently
+ * discarded.
+ */
+ if (icmph->type > NR_ICMP_TYPES)
+ goto error;
+
+
+ /*
+ * Parse the ICMP message
+ */
+
+ if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
+ /*
+ * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
+ * silently ignored (we let user decide with a sysctl).
+ * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
+ * discarded if to broadcast/multicast.
+ */
+ if (icmph->type == ICMP_ECHO &&
+ sysctl_icmp_echo_ignore_broadcasts) {
+ goto error;
+ }
+ if (icmph->type != ICMP_ECHO &&
+ icmph->type != ICMP_TIMESTAMP &&
+ icmph->type != ICMP_ADDRESS &&
+ icmph->type != ICMP_ADDRESSREPLY) {
+ goto error;
+ }
+ }
+
+ ICMP_INC_STATS_BH(icmp_pointers[icmph->type].input_entry);
+ icmp_pointers[icmph->type].handler(skb);
+
+drop:
+ kfree_skb(skb);
+ return 0;
+error:
+ ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
+ goto drop;
+}
+
+/*
+ * This table is the definition of how we handle ICMP.
+ */
+static struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
+ [ICMP_ECHOREPLY] = {
+ .output_entry = ICMP_MIB_OUTECHOREPS,
+ .input_entry = ICMP_MIB_INECHOREPS,
+ .handler = icmp_discard,
+ },
+ [1] = {
+ .output_entry = ICMP_MIB_DUMMY,
+ .input_entry = ICMP_MIB_INERRORS,
+ .handler = icmp_discard,
+ .error = 1,
+ },
+ [2] = {
+ .output_entry = ICMP_MIB_DUMMY,
+ .input_entry = ICMP_MIB_INERRORS,
+ .handler = icmp_discard,
+ .error = 1,
+ },
+ [ICMP_DEST_UNREACH] = {
+ .output_entry = ICMP_MIB_OUTDESTUNREACHS,
+ .input_entry = ICMP_MIB_INDESTUNREACHS,
+ .handler = icmp_unreach,
+ .error = 1,
+ },
+ [ICMP_SOURCE_QUENCH] = {
+ .output_entry = ICMP_MIB_OUTSRCQUENCHS,
+ .input_entry = ICMP_MIB_INSRCQUENCHS,
+ .handler = icmp_unreach,
+ .error = 1,
+ },
+ [ICMP_REDIRECT] = {
+ .output_entry = ICMP_MIB_OUTREDIRECTS,
+ .input_entry = ICMP_MIB_INREDIRECTS,
+ .handler = icmp_redirect,
+ .error = 1,
+ },
+ [6] = {
+ .output_entry = ICMP_MIB_DUMMY,
+ .input_entry = ICMP_MIB_INERRORS,
+ .handler = icmp_discard,
+ .error = 1,
+ },
+ [7] = {
+ .output_entry = ICMP_MIB_DUMMY,
+ .input_entry = ICMP_MIB_INERRORS,
+ .handler = icmp_discard,
+ .error = 1,
+ },
+ [ICMP_ECHO] = {
+ .output_entry = ICMP_MIB_OUTECHOS,
+ .input_entry = ICMP_MIB_INECHOS,
+ .handler = icmp_echo,
+ },
+ [9] = {
+ .output_entry = ICMP_MIB_DUMMY,
+ .input_entry = ICMP_MIB_INERRORS,
+ .handler = icmp_discard,
+ .error = 1,
+ },
+ [10] = {
+ .output_entry = ICMP_MIB_DUMMY,
+ .input_entry = ICMP_MIB_INERRORS,
+ .handler = icmp_discard,
+ .error = 1,
+ },
+ [ICMP_TIME_EXCEEDED] = {
+ .output_entry = ICMP_MIB_OUTTIMEEXCDS,
+ .input_entry = ICMP_MIB_INTIMEEXCDS,
+ .handler = icmp_unreach,
+ .error = 1,
+ },
+ [ICMP_PARAMETERPROB] = {
+ .output_entry = ICMP_MIB_OUTPARMPROBS,
+ .input_entry = ICMP_MIB_INPARMPROBS,
+ .handler = icmp_unreach,
+ .error = 1,
+ },
+ [ICMP_TIMESTAMP] = {
+ .output_entry = ICMP_MIB_OUTTIMESTAMPS,
+ .input_entry = ICMP_MIB_INTIMESTAMPS,
+ .handler = icmp_timestamp,
+ },
+ [ICMP_TIMESTAMPREPLY] = {
+ .output_entry = ICMP_MIB_OUTTIMESTAMPREPS,
+ .input_entry = ICMP_MIB_INTIMESTAMPREPS,
+ .handler = icmp_discard,
+ },
+ [ICMP_INFO_REQUEST] = {
+ .output_entry = ICMP_MIB_DUMMY,
+ .input_entry = ICMP_MIB_DUMMY,
+ .handler = icmp_discard,
+ },
+ [ICMP_INFO_REPLY] = {
+ .output_entry = ICMP_MIB_DUMMY,
+ .input_entry = ICMP_MIB_DUMMY,
+ .handler = icmp_discard,
+ },
+ [ICMP_ADDRESS] = {
+ .output_entry = ICMP_MIB_OUTADDRMASKS,
+ .input_entry = ICMP_MIB_INADDRMASKS,
+ .handler = icmp_address,
+ },
+ [ICMP_ADDRESSREPLY] = {
+ .output_entry = ICMP_MIB_OUTADDRMASKREPS,
+ .input_entry = ICMP_MIB_INADDRMASKREPS,
+ .handler = icmp_address_reply,
+ },
+};
+
+void __init icmp_init(struct net_proto_family *ops)
+{
+ struct inet_sock *inet;
+ int i;
+
+ for (i = 0; i < NR_CPUS; i++) {
+ int err;
+
+ if (!cpu_possible(i))
+ continue;
+
+ err = sock_create_kern(PF_INET, SOCK_RAW, IPPROTO_ICMP,
+ &per_cpu(__icmp_socket, i));
+
+ if (err < 0)
+ panic("Failed to create the ICMP control socket.\n");
+
+ per_cpu(__icmp_socket, i)->sk->sk_allocation = GFP_ATOMIC;
+
+ /* Enough space for 2 64K ICMP packets, including
+ * sk_buff struct overhead.
+ */
+ per_cpu(__icmp_socket, i)->sk->sk_sndbuf =
+ (2 * ((64 * 1024) + sizeof(struct sk_buff)));
+
+ inet = inet_sk(per_cpu(__icmp_socket, i)->sk);
+ inet->uc_ttl = -1;
+ inet->pmtudisc = IP_PMTUDISC_DONT;
+
+ /* Unhash it so that IP input processing does not even
+ * see it, we do not wish this socket to see incoming
+ * packets.
+ */
+ per_cpu(__icmp_socket, i)->sk->sk_prot->unhash(per_cpu(__icmp_socket, i)->sk);
+ }
+}
+
+EXPORT_SYMBOL(icmp_err_convert);
+EXPORT_SYMBOL(icmp_send);
+EXPORT_SYMBOL(icmp_statistics);
+EXPORT_SYMBOL(xrlim_allow);
generated by cgit v1.2.3-18-g5258 (git 2.32.0) at 2024-12-02 22:44:16 +0000