icmp.c
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上传日期:2013-04-10
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- /*
- * Internet Control Message Protocol (ICMPv6)
- * Linux INET6 implementation
- *
- * Authors:
- * Pedro Roque <roque@di.fc.ul.pt>
- *
- * $Id: icmp.c,v 1.37 2001/09/18 22:29:10 davem Exp $
- *
- * Based on net/ipv4/icmp.c
- *
- * RFC 1885
- *
- * 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.
- */
- /*
- * Changes:
- *
- * Andi Kleen : exception handling
- * Andi Kleen add rate limits. never reply to a icmp.
- * add more length checks and other fixes.
- * yoshfuji : ensure to sent parameter problem for
- * fragments.
- */
- #define __NO_VERSION__
- #include <linux/module.h>
- #include <linux/errno.h>
- #include <linux/types.h>
- #include <linux/socket.h>
- #include <linux/in.h>
- #include <linux/kernel.h>
- #include <linux/sched.h>
- #include <linux/sockios.h>
- #include <linux/net.h>
- #include <linux/skbuff.h>
- #include <linux/init.h>
- #include <linux/inet.h>
- #include <linux/netdevice.h>
- #include <linux/icmpv6.h>
- #include <net/ip.h>
- #include <net/sock.h>
- #include <net/ipv6.h>
- #include <net/checksum.h>
- #include <net/protocol.h>
- #include <net/raw.h>
- #include <net/rawv6.h>
- #include <net/transp_v6.h>
- #include <net/ip6_route.h>
- #include <net/addrconf.h>
- #include <net/icmp.h>
- #include <asm/uaccess.h>
- #include <asm/system.h>
- struct icmpv6_mib icmpv6_statistics[NR_CPUS*2];
- /*
- * ICMP socket for flow control.
- */
- struct socket *icmpv6_socket;
- int icmpv6_rcv(struct sk_buff *skb);
- static struct inet6_protocol icmpv6_protocol =
- {
- icmpv6_rcv, /* handler */
- NULL, /* error control */
- NULL, /* next */
- IPPROTO_ICMPV6, /* protocol ID */
- 0, /* copy */
- NULL, /* data */
- "ICMPv6" /* name */
- };
- struct icmpv6_msg {
- struct icmp6hdr icmph;
- struct sk_buff *skb;
- int offset;
- struct in6_addr *daddr;
- int len;
- __u32 csum;
- };
- static int icmpv6_xmit_holder = -1;
- static int icmpv6_xmit_lock_bh(void)
- {
- if (!spin_trylock(&icmpv6_socket->sk->lock.slock)) {
- if (icmpv6_xmit_holder == smp_processor_id())
- return -EAGAIN;
- spin_lock(&icmpv6_socket->sk->lock.slock);
- }
- icmpv6_xmit_holder = smp_processor_id();
- return 0;
- }
- static __inline__ int icmpv6_xmit_lock(void)
- {
- int ret;
- local_bh_disable();
- ret = icmpv6_xmit_lock_bh();
- if (ret)
- local_bh_enable();
- return ret;
- }
- static void icmpv6_xmit_unlock_bh(void)
- {
- icmpv6_xmit_holder = -1;
- spin_unlock(&icmpv6_socket->sk->lock.slock);
- }
- static __inline__ void icmpv6_xmit_unlock(void)
- {
- icmpv6_xmit_unlock_bh();
- local_bh_enable();
- }
- /*
- * getfrag callback
- */
- static int icmpv6_getfrag(const void *data, struct in6_addr *saddr,
- char *buff, unsigned int offset, unsigned int len)
- {
- struct icmpv6_msg *msg = (struct icmpv6_msg *) data;
- struct icmp6hdr *icmph;
- __u32 csum;
- if (offset) {
- csum = skb_copy_and_csum_bits(msg->skb, msg->offset +
- (offset - sizeof(struct icmp6hdr)),
- buff, len, msg->csum);
- msg->csum = csum;
- return 0;
- }
- csum = csum_partial_copy_nocheck((void *) &msg->icmph, buff,
- sizeof(struct icmp6hdr), msg->csum);
- csum = skb_copy_and_csum_bits(msg->skb, msg->offset,
- buff + sizeof(struct icmp6hdr),
- len - sizeof(struct icmp6hdr), csum);
- icmph = (struct icmp6hdr *) buff;
- icmph->icmp6_cksum = csum_ipv6_magic(saddr, msg->daddr, msg->len,
- IPPROTO_ICMPV6, csum);
- return 0;
- }
- /*
- * Slightly more convenient version of icmpv6_send.
- */
- void icmpv6_param_prob(struct sk_buff *skb, int code, int pos)
- {
- icmpv6_send(skb, ICMPV6_PARAMPROB, code, pos, skb->dev);
- kfree_skb(skb);
- }
- /*
- * Figure out, may we reply to this packet with icmp error.
- *
- * We do not reply, if:
- * - it was icmp error message.
- * - it is truncated, so that it is known, that protocol is ICMPV6
- * (i.e. in the middle of some exthdr)
- *
- * --ANK (980726)
- */
- static int is_ineligible(struct sk_buff *skb)
- {
- int ptr = (u8*)(skb->nh.ipv6h+1) - skb->data;
- int len = skb->len - ptr;
- __u8 nexthdr = skb->nh.ipv6h->nexthdr;
- if (len < 0)
- return 1;
- ptr = ipv6_skip_exthdr(skb, ptr, &nexthdr, len);
- if (ptr < 0)
- return 0;
- if (nexthdr == IPPROTO_ICMPV6) {
- u8 type;
- if (skb_copy_bits(skb, ptr+offsetof(struct icmp6hdr, icmp6_type),
- &type, 1)
- || !(type & ICMPV6_INFOMSG_MASK))
- return 1;
- }
- return 0;
- }
- int sysctl_icmpv6_time = 1*HZ;
- /*
- * Check the ICMP output rate limit
- */
- static inline int icmpv6_xrlim_allow(struct sock *sk, int type,
- struct flowi *fl)
- {
- struct dst_entry *dst;
- int res = 0;
- /* Informational messages are not limited. */
- if (type & ICMPV6_INFOMSG_MASK)
- return 1;
- /* Do not limit pmtu discovery, it would break it. */
- if (type == ICMPV6_PKT_TOOBIG)
- return 1;
- /*
- * Look up the output route.
- * XXX: perhaps the expire for routing entries cloned by
- * this lookup should be more aggressive (not longer than timeout).
- */
- dst = ip6_route_output(sk, fl);
- if (dst->error) {
- IP6_INC_STATS(Ip6OutNoRoutes);
- } else if (dst->dev && (dst->dev->flags&IFF_LOOPBACK)) {
- res = 1;
- } else {
- struct rt6_info *rt = (struct rt6_info *)dst;
- int tmo = sysctl_icmpv6_time;
- /* Give more bandwidth to wider prefixes. */
- if (rt->rt6i_dst.plen < 128)
- tmo >>= ((128 - rt->rt6i_dst.plen)>>5);
- res = xrlim_allow(dst, tmo);
- }
- dst_release(dst);
- return res;
- }
- /*
- * an inline helper for the "simple" if statement below
- * checks if parameter problem report is caused by an
- * unrecognized IPv6 option that has the Option Type
- * highest-order two bits set to 10
- */
- static __inline__ int opt_unrec(struct sk_buff *skb, __u32 offset)
- {
- u8 optval;
- offset += skb->nh.raw - skb->data;
- if (skb_copy_bits(skb, offset, &optval, 1))
- return 1;
- return (optval&0xC0) == 0x80;
- }
- /*
- * Send an ICMP message in response to a packet in error
- */
- void icmpv6_send(struct sk_buff *skb, int type, int code, __u32 info,
- struct net_device *dev)
- {
- struct ipv6hdr *hdr = skb->nh.ipv6h;
- struct sock *sk = icmpv6_socket->sk;
- struct in6_addr *saddr = NULL;
- int iif = 0;
- struct icmpv6_msg msg;
- struct flowi fl;
- int addr_type = 0;
- int len;
- if ((u8*)hdr < skb->head || (u8*)(hdr+1) > skb->tail)
- return;
- /*
- * Make sure we respect the rules
- * i.e. RFC 1885 2.4(e)
- * Rule (e.1) is enforced by not using icmpv6_send
- * in any code that processes icmp errors.
- */
- addr_type = ipv6_addr_type(&hdr->daddr);
- if (ipv6_chk_addr(&hdr->daddr, skb->dev))
- saddr = &hdr->daddr;
- /*
- * Dest addr check
- */
- if ((addr_type & IPV6_ADDR_MULTICAST || skb->pkt_type != PACKET_HOST)) {
- if (type != ICMPV6_PKT_TOOBIG &&
- !(type == ICMPV6_PARAMPROB &&
- code == ICMPV6_UNK_OPTION &&
- (opt_unrec(skb, info))))
- return;
- saddr = NULL;
- }
- addr_type = ipv6_addr_type(&hdr->saddr);
- /*
- * Source addr check
- */
- if (addr_type & IPV6_ADDR_LINKLOCAL)
- iif = skb->dev->ifindex;
- /*
- * Must not send if we know that source is Anycast also.
- * for now we don't know that.
- */
- if ((addr_type == IPV6_ADDR_ANY) || (addr_type & IPV6_ADDR_MULTICAST)) {
- if (net_ratelimit())
- printk(KERN_DEBUG "icmpv6_send: addr_any/mcast sourcen");
- return;
- }
- /*
- * Never answer to a ICMP packet.
- */
- if (is_ineligible(skb)) {
- if (net_ratelimit())
- printk(KERN_DEBUG "icmpv6_send: no reply to icmp errorn");
- return;
- }
- fl.proto = IPPROTO_ICMPV6;
- fl.nl_u.ip6_u.daddr = &hdr->saddr;
- fl.nl_u.ip6_u.saddr = saddr;
- fl.oif = iif;
- fl.fl6_flowlabel = 0;
- fl.uli_u.icmpt.type = type;
- fl.uli_u.icmpt.code = code;
- if (icmpv6_xmit_lock())
- return;
- if (!icmpv6_xrlim_allow(sk, type, &fl))
- goto out;
- /*
- * ok. kick it. checksum will be provided by the
- * getfrag_t callback.
- */
- msg.icmph.icmp6_type = type;
- msg.icmph.icmp6_code = code;
- msg.icmph.icmp6_cksum = 0;
- msg.icmph.icmp6_pointer = htonl(info);
- msg.skb = skb;
- msg.offset = skb->nh.raw - skb->data;
- msg.csum = 0;
- msg.daddr = &hdr->saddr;
- len = skb->len - msg.offset + sizeof(struct icmp6hdr);
- len = min_t(unsigned int, len, IPV6_MIN_MTU - sizeof(struct ipv6hdr));
- if (len < 0) {
- if (net_ratelimit())
- printk(KERN_DEBUG "icmp: len problemn");
- goto out;
- }
- msg.len = len;
- ip6_build_xmit(sk, icmpv6_getfrag, &msg, &fl, len, NULL, -1,
- MSG_DONTWAIT);
- if (type >= ICMPV6_DEST_UNREACH && type <= ICMPV6_PARAMPROB)
- (&(icmpv6_statistics[smp_processor_id()*2].Icmp6OutDestUnreachs))[type-1]++;
- ICMP6_INC_STATS_BH(Icmp6OutMsgs);
- out:
- icmpv6_xmit_unlock();
- }
- static void icmpv6_echo_reply(struct sk_buff *skb)
- {
- struct sock *sk = icmpv6_socket->sk;
- struct icmp6hdr *icmph = (struct icmp6hdr *) skb->h.raw;
- struct in6_addr *saddr;
- struct icmpv6_msg msg;
- struct flowi fl;
- saddr = &skb->nh.ipv6h->daddr;
- if (ipv6_addr_type(saddr) & IPV6_ADDR_MULTICAST)
- saddr = NULL;
- msg.icmph.icmp6_type = ICMPV6_ECHO_REPLY;
- msg.icmph.icmp6_code = 0;
- msg.icmph.icmp6_cksum = 0;
- msg.icmph.icmp6_identifier = icmph->icmp6_identifier;
- msg.icmph.icmp6_sequence = icmph->icmp6_sequence;
- msg.skb = skb;
- msg.offset = 0;
- msg.csum = 0;
- msg.len = skb->len + sizeof(struct icmp6hdr);
- msg.daddr = &skb->nh.ipv6h->saddr;
- fl.proto = IPPROTO_ICMPV6;
- fl.nl_u.ip6_u.daddr = msg.daddr;
- fl.nl_u.ip6_u.saddr = saddr;
- fl.oif = skb->dev->ifindex;
- fl.fl6_flowlabel = 0;
- fl.uli_u.icmpt.type = ICMPV6_ECHO_REPLY;
- fl.uli_u.icmpt.code = 0;
- if (icmpv6_xmit_lock_bh())
- return;
- ip6_build_xmit(sk, icmpv6_getfrag, &msg, &fl, msg.len, NULL, -1,
- MSG_DONTWAIT);
- ICMP6_INC_STATS_BH(Icmp6OutEchoReplies);
- ICMP6_INC_STATS_BH(Icmp6OutMsgs);
- icmpv6_xmit_unlock_bh();
- }
- static void icmpv6_notify(struct sk_buff *skb, int type, int code, u32 info)
- {
- struct in6_addr *saddr, *daddr;
- struct inet6_protocol *ipprot;
- struct sock *sk;
- int inner_offset;
- int hash;
- u8 nexthdr;
- if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
- return;
- nexthdr = ((struct ipv6hdr *)skb->data)->nexthdr;
- if (ipv6_ext_hdr(nexthdr)) {
- /* now skip over extension headers */
- inner_offset = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr, skb->len - sizeof(struct ipv6hdr));
- if (inner_offset<0)
- return;
- } else {
- inner_offset = sizeof(struct ipv6hdr);
- }
- /* Checkin header including 8 bytes of inner protocol header. */
- if (!pskb_may_pull(skb, inner_offset+8))
- return;
- saddr = &skb->nh.ipv6h->saddr;
- daddr = &skb->nh.ipv6h->daddr;
- /* BUGGG_FUTURE: we should try to parse exthdrs in this packet.
- Without this we will not able f.e. to make source routed
- pmtu discovery.
- Corresponding argument (opt) to notifiers is already added.
- --ANK (980726)
- */
- hash = nexthdr & (MAX_INET_PROTOS - 1);
- for (ipprot = (struct inet6_protocol *) inet6_protos[hash];
- ipprot != NULL;
- ipprot=(struct inet6_protocol *)ipprot->next) {
- if (ipprot->protocol != nexthdr)
- continue;
- if (ipprot->err_handler)
- ipprot->err_handler(skb, NULL, type, code, inner_offset, info);
- }
- read_lock(&raw_v6_lock);
- if ((sk = raw_v6_htable[hash]) != NULL) {
- while((sk = __raw_v6_lookup(sk, nexthdr, daddr, saddr))) {
- rawv6_err(sk, skb, NULL, type, code, inner_offset, info);
- sk = sk->next;
- }
- }
- read_unlock(&raw_v6_lock);
- }
-
- /*
- * Handle icmp messages
- */
- int icmpv6_rcv(struct sk_buff *skb)
- {
- struct net_device *dev = skb->dev;
- struct in6_addr *saddr, *daddr;
- struct ipv6hdr *orig_hdr;
- struct icmp6hdr *hdr;
- int type;
- ICMP6_INC_STATS_BH(Icmp6InMsgs);
- saddr = &skb->nh.ipv6h->saddr;
- daddr = &skb->nh.ipv6h->daddr;
- /* Perform checksum. */
- if (skb->ip_summed == CHECKSUM_HW) {
- skb->ip_summed = CHECKSUM_UNNECESSARY;
- if (csum_ipv6_magic(saddr, daddr, skb->len, IPPROTO_ICMPV6,
- skb->csum)) {
- if (net_ratelimit())
- printk(KERN_DEBUG "ICMPv6 hw checksum failedn");
- skb->ip_summed = CHECKSUM_NONE;
- }
- }
- if (skb->ip_summed == CHECKSUM_NONE) {
- if (csum_ipv6_magic(saddr, daddr, skb->len, IPPROTO_ICMPV6,
- skb_checksum(skb, 0, skb->len, 0))) {
- if (net_ratelimit())
- printk(KERN_DEBUG "ICMPv6 checksum failed [%04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x > %04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x]n",
- ntohs(saddr->s6_addr16[0]),
- ntohs(saddr->s6_addr16[1]),
- ntohs(saddr->s6_addr16[2]),
- ntohs(saddr->s6_addr16[3]),
- ntohs(saddr->s6_addr16[4]),
- ntohs(saddr->s6_addr16[5]),
- ntohs(saddr->s6_addr16[6]),
- ntohs(saddr->s6_addr16[7]),
- ntohs(daddr->s6_addr16[0]),
- ntohs(daddr->s6_addr16[1]),
- ntohs(daddr->s6_addr16[2]),
- ntohs(daddr->s6_addr16[3]),
- ntohs(daddr->s6_addr16[4]),
- ntohs(daddr->s6_addr16[5]),
- ntohs(daddr->s6_addr16[6]),
- ntohs(daddr->s6_addr16[7]));
- goto discard_it;
- }
- }
- if (!pskb_pull(skb, sizeof(struct icmp6hdr)))
- goto discard_it;
- hdr = (struct icmp6hdr *) skb->h.raw;
- type = hdr->icmp6_type;
- if (type >= ICMPV6_DEST_UNREACH && type <= ICMPV6_PARAMPROB)
- (&icmpv6_statistics[smp_processor_id()*2].Icmp6InDestUnreachs)[type-ICMPV6_DEST_UNREACH]++;
- else if (type >= ICMPV6_ECHO_REQUEST && type <= NDISC_REDIRECT)
- (&icmpv6_statistics[smp_processor_id()*2].Icmp6InEchos)[type-ICMPV6_ECHO_REQUEST]++;
- switch (type) {
- case ICMPV6_ECHO_REQUEST:
- icmpv6_echo_reply(skb);
- break;
- case ICMPV6_ECHO_REPLY:
- /* we coulnd't care less */
- break;
- case ICMPV6_PKT_TOOBIG:
- /* BUGGG_FUTURE: if packet contains rthdr, we cannot update
- standard destination cache. Seems, only "advanced"
- destination cache will allow to solve this problem
- --ANK (980726)
- */
- if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
- goto discard_it;
- hdr = (struct icmp6hdr *) skb->h.raw;
- orig_hdr = (struct ipv6hdr *) (hdr + 1);
- rt6_pmtu_discovery(&orig_hdr->daddr, &orig_hdr->saddr, dev,
- ntohl(hdr->icmp6_mtu));
- /*
- * Drop through to notify
- */
- case ICMPV6_DEST_UNREACH:
- case ICMPV6_TIME_EXCEED:
- case ICMPV6_PARAMPROB:
- icmpv6_notify(skb, type, hdr->icmp6_code, hdr->icmp6_mtu);
- break;
- case NDISC_ROUTER_SOLICITATION:
- case NDISC_ROUTER_ADVERTISEMENT:
- case NDISC_NEIGHBOUR_SOLICITATION:
- case NDISC_NEIGHBOUR_ADVERTISEMENT:
- case NDISC_REDIRECT:
- if (skb_is_nonlinear(skb) &&
- skb_linearize(skb, GFP_ATOMIC) != 0) {
- kfree_skb(skb);
- return 0;
- }
- ndisc_rcv(skb);
- break;
- case ICMPV6_MGM_QUERY:
- igmp6_event_query(skb);
- break;
- case ICMPV6_MGM_REPORT:
- igmp6_event_report(skb);
- break;
- case ICMPV6_MGM_REDUCTION:
- break;
- default:
- if (net_ratelimit())
- printk(KERN_DEBUG "icmpv6: msg of unkown typen");
- /* informational */
- if (type & ICMPV6_INFOMSG_MASK)
- break;
- /*
- * error of unkown type.
- * must pass to upper level
- */
- icmpv6_notify(skb, type, hdr->icmp6_code, hdr->icmp6_mtu);
- };
- kfree_skb(skb);
- return 0;
- discard_it:
- ICMP6_INC_STATS_BH(Icmp6InErrors);
- kfree_skb(skb);
- return 0;
- }
- int __init icmpv6_init(struct net_proto_family *ops)
- {
- struct sock *sk;
- int err;
- icmpv6_socket = sock_alloc();
- if (icmpv6_socket == NULL) {
- printk(KERN_ERR
- "Failed to create the ICMP6 control socket.n");
- return -1;
- }
- icmpv6_socket->inode->i_uid = 0;
- icmpv6_socket->inode->i_gid = 0;
- icmpv6_socket->type = SOCK_RAW;
- if ((err = ops->create(icmpv6_socket, IPPROTO_ICMPV6)) < 0) {
- printk(KERN_ERR
- "Failed to initialize the ICMP6 control socket (err %d).n",
- err);
- sock_release(icmpv6_socket);
- icmpv6_socket = NULL; /* for safety */
- return err;
- }
- sk = icmpv6_socket->sk;
- sk->allocation = GFP_ATOMIC;
- sk->sndbuf = SK_WMEM_MAX*2;
- sk->prot->unhash(sk);
- inet6_add_protocol(&icmpv6_protocol);
- return 0;
- }
- void icmpv6_cleanup(void)
- {
- sock_release(icmpv6_socket);
- icmpv6_socket = NULL; /* For safety. */
- inet6_del_protocol(&icmpv6_protocol);
- }
- static struct icmp6_err {
- int err;
- int fatal;
- } tab_unreach[] = {
- { ENETUNREACH, 0}, /* NOROUTE */
- { EACCES, 1}, /* ADM_PROHIBITED */
- { EHOSTUNREACH, 0}, /* Was NOT_NEIGHBOUR, now reserved */
- { EHOSTUNREACH, 0}, /* ADDR_UNREACH */
- { ECONNREFUSED, 1}, /* PORT_UNREACH */
- };
- int icmpv6_err_convert(int type, int code, int *err)
- {
- int fatal = 0;
- *err = EPROTO;
- switch (type) {
- case ICMPV6_DEST_UNREACH:
- fatal = 1;
- if (code <= ICMPV6_PORT_UNREACH) {
- *err = tab_unreach[code].err;
- fatal = tab_unreach[code].fatal;
- }
- break;
- case ICMPV6_PKT_TOOBIG:
- *err = EMSGSIZE;
- break;
-
- case ICMPV6_PARAMPROB:
- *err = EPROTO;
- fatal = 1;
- break;
- case ICMPV6_TIME_EXCEED:
- *err = EHOSTUNREACH;
- break;
- };
- return fatal;
- }