528 lines
14 KiB
C
528 lines
14 KiB
C
/*
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* Copyright (c) 1982, 1986 Regents of the University of California.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms are permitted
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* provided that this notice is preserved and that due credit is given
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* to the University of California at Berkeley. The name of the University
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* may not be used to endorse or promote products derived from this
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* software without specific prior written permission. This software
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* is provided ``as is'' without express or implied warranty.
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*
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* @(#)ip_icmp.c 1.1 94/10/31 SMI; from UCB 7.7 12/7/87
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/mbuf.h>
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#include <sys/protosw.h>
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#include <sys/socket.h>
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#include <sys/time.h>
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#include <sys/kernel.h>
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#include <net/route.h>
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#include <net/if.h>
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#include <netinet/in.h>
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#include <netinet/in_systm.h>
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#include <netinet/ip.h>
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#include <netinet/ip_icmp.h>
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#include <netinet/icmp_var.h>
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#include <netinet/in_var.h>
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#include <netinet/udp.h>
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#include <netinet/ip_var.h>
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#include <netinet/in_pcb.h>
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#include <netinet/udp_var.h>
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#include <netinet/tcp.h>
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#include <netinet/tcp_fsm.h>
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#include <netinet/tcp_timer.h>
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#include <netinet/tcp_var.h>
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#include <netinet/tcpip.h>
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#ifdef ICMPPRINTFS
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/*
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* ICMP routines: error generation, receive packet processing, and
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* routines to turnaround packets back to the originator, and
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* host table maintenance routines.
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*/
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int icmpprintfs = 0;
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#endif
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/*
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* Generate an error packet of type error
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* in response to bad packet ip.
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*/
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/*VARARGS4*/
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icmp_error(oip, type, code, ifp, dest)
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struct ip *oip;
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int type, code;
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struct ifnet *ifp;
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struct in_addr dest;
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{
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register unsigned oiplen = oip->ip_hl << 2;
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register struct icmp *icp;
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struct mbuf *m,*om=dtom(oip);
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struct ip *nip;
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unsigned icmplen;
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#ifdef ICMPPRINTFS
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if (icmpprintfs)
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printf("icmp_error(%x, %d, %d)\n", oip, type, code);
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#endif
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if (type != ICMP_REDIRECT)
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icmpstat.icps_error++;
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/*
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* Don't send error if not the first fragment of message.
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* Don't error if the old packet protocol was ICMP
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* error message, only known informational types.
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*/
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if (oip->ip_off &~ (IP_MF|IP_DF))
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goto free;
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if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
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!ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiplen))->icmp_type)) {
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icmpstat.icps_oldicmp++;
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goto free;
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}
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/*
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* First, formulate icmp message
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*/
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m = m_get(M_DONTWAIT, MT_HEADER);
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if (m == NULL)
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goto free;
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icmplen = oiplen + MIN(8, oip->ip_len);
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m->m_len = icmplen + ICMP_MINLEN;
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m->m_off = MMAXOFF - m->m_len;
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icp = mtod(m, struct icmp *);
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if ((u_int)type > ICMP_MAXTYPE)
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panic("icmp_error");
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icmpstat.icps_outhist[type]++;
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icp->icmp_type = type;
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if (type == ICMP_REDIRECT)
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icp->icmp_gwaddr = dest;
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else
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icp->icmp_void = 0;
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if (type == ICMP_PARAMPROB) {
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icp->icmp_pptr = code;
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code = 0;
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}
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icp->icmp_code = code;
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if (om->m_len < icmplen) {
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if ((om = m_pullup(om, (int)icmplen)) == 0) {
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m_freem(m);
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return;
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}
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oip = mtod(om, struct ip *);
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}
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bcopy((caddr_t)oip, (caddr_t)&icp->icmp_ip, icmplen);
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nip = &icp->icmp_ip;
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nip->ip_len += oiplen;
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nip->ip_len = htons((u_short)nip->ip_len);
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/*
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* Now, copy old ip header in front of icmp message.
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*/
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if (m->m_len + oiplen > MLEN)
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oiplen = sizeof(struct ip);
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if (m->m_len + oiplen > MLEN)
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panic("icmp len");
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m->m_off -= oiplen;
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m->m_len += oiplen;
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nip = mtod(m, struct ip *);
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bcopy((caddr_t)oip, (caddr_t)nip, oiplen);
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nip->ip_len = m->m_len;
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nip->ip_p = IPPROTO_ICMP;
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icmp_reflect(nip, ifp);
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free:
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m_freem(dtom(oip));
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}
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static struct sockproto icmproto = { AF_INET, IPPROTO_ICMP };
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static struct sockaddr_in icmpsrc = { AF_INET };
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static struct sockaddr_in icmpdst = { AF_INET };
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static struct sockaddr_in icmpgw = { AF_INET };
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struct in_ifaddr *ifptoia();
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/*
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* Process a received ICMP message.
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*/
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icmp_input(m, ifp)
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register struct mbuf *m;
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struct ifnet *ifp;
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{
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register struct icmp *icp;
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register struct ip *ip = mtod(m, struct ip *);
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int icmplen = ip->ip_len, hlen = ip->ip_hl << 2;
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register int i;
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struct in_ifaddr *ia;
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int (*ctlfunc)(), code;
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extern u_char ip_protox[];
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extern struct in_addr in_makeaddr();
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/*
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* Locate icmp structure in mbuf, and check
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* that not corrupted and of at least minimum length.
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*/
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#ifdef ICMPPRINTFS
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if (icmpprintfs)
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printf("icmp_input from %x, len %d\n", ip->ip_src, icmplen);
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#endif
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if (icmplen < ICMP_MINLEN) {
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icmpstat.icps_tooshort++;
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goto free;
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}
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i = hlen + MIN(icmplen, ICMP_ADVLENMIN);
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if ((m->m_off > MMAXOFF || m->m_len < i) &&
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(m = m_pullup(m, i)) == 0) {
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icmpstat.icps_tooshort++;
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return;
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}
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ip = mtod(m, struct ip *);
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m->m_len -= hlen;
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m->m_off += hlen;
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icp = mtod(m, struct icmp *);
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if (in_cksum(m, icmplen)) {
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icmpstat.icps_checksum++;
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goto free;
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}
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m->m_len += hlen;
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m->m_off -= hlen;
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#ifdef ICMPPRINTFS
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/*
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* Message type specific processing.
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*/
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if (icmpprintfs)
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printf("icmp_input, type %d code %d\n", icp->icmp_type,
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icp->icmp_code);
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#endif
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if (icp->icmp_type > ICMP_MAXTYPE)
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goto raw;
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icmpstat.icps_inhist[icp->icmp_type]++;
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/*
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* Weed out ICMP messages which dont describe an extact and existing
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* TCP connection - *IF* they are destined for a TCP connection.
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* If they are not, there isnt much more checking which is worth
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* doing - udp seems immune to these in some wierd way.
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* There is still a chance, however, that someone could build a
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* fake packet and affect us if they have the correct details.
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* Perhaps with more checking (against sequence numbers and window
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* size, etc) the fakes can be totally negated.
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* Darren Reed. (avalon@coombs.anu.edu.au) 23rd April 1992
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*/
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switch(icp->icmp_type) {
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case ICMP_UNREACH:
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case ICMP_SOURCEQUENCH:
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case ICMP_TIMXCEED:
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case ICMP_PARAMPROB:
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case ICMP_REDIRECT:
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if (icp->icmp_ip.ip_p == IPPROTO_TCP)
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if (!lookuptcp(icp->icmp_data))
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goto free;
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}
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code = icp->icmp_code;
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switch (icp->icmp_type) {
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case ICMP_UNREACH:
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if (code > 5)
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goto badcode;
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code += PRC_UNREACH_NET;
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goto deliver;
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case ICMP_TIMXCEED:
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if (code > 1)
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goto badcode;
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code += PRC_TIMXCEED_INTRANS;
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goto deliver;
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case ICMP_PARAMPROB:
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if (code)
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goto badcode;
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code = PRC_PARAMPROB;
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goto deliver;
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case ICMP_SOURCEQUENCH:
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if (code)
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goto badcode;
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code = PRC_QUENCH;
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deliver:
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/*
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* Problem with datagram; advise higher level routines.
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*/
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icp->icmp_ip.ip_len = ntohs((u_short)icp->icmp_ip.ip_len);
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if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp)) {
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icmpstat.icps_badlen++;
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goto free;
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}
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#ifdef ICMPPRINTFS
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if (icmpprintfs)
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printf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
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#endif
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icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
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icmpsrc.sin_port = ((struct udpiphdr *)&(icp->icmp_ip))->ui_dport;
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if (ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput)
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(*ctlfunc)(code, (struct sockaddr *)&icmpsrc);
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break;
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badcode:
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icmpstat.icps_badcode++;
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break;
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case ICMP_ECHO:
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icp->icmp_type = ICMP_ECHOREPLY;
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goto reflect;
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case ICMP_TSTAMP:
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if (icmplen < ICMP_TSLEN) {
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icmpstat.icps_badlen++;
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break;
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}
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icp->icmp_type = ICMP_TSTAMPREPLY;
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icp->icmp_rtime = iptime();
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icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */
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goto reflect;
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case ICMP_IREQ:
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#define satosin(sa) ((struct sockaddr_in *)(sa))
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if (in_netof(ip->ip_src) == 0 && (ia = ifptoia(ifp)))
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ip->ip_src = in_makeaddr(in_netof(IA_SIN(ia)->sin_addr),
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in_lnaof(ip->ip_src));
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icp->icmp_type = ICMP_IREQREPLY;
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goto reflect;
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case ICMP_MASKREQ:
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if (icmplen < ICMP_MASKLEN || (ia = ifptoia(ifp)) == 0)
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break;
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icp->icmp_type = ICMP_MASKREPLY;
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icp->icmp_mask = htonl(ia->ia_subnetmask);
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if (ip->ip_src.s_addr == 0) {
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if (ia->ia_ifp->if_flags & IFF_BROADCAST)
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ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr;
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else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT)
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ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr;
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}
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reflect:
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ip->ip_len += hlen; /* since ip_input deducts this */
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icmpstat.icps_reflect++;
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icmpstat.icps_outhist[icp->icmp_type]++;
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icmp_reflect(ip, ifp);
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return;
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case ICMP_REDIRECT:
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if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp)) {
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icmpstat.icps_badlen++;
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break;
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}
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/*
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* Short circuit routing redirects to force
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* immediate change in the kernel's routing
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* tables. The message is also handed to anyone
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* listening on a raw socket (e.g. the routing
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* daemon for use in updating its tables).
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*/
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icmpgw.sin_addr = ip->ip_src;
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icmpdst.sin_addr = icp->icmp_gwaddr;
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#ifdef ICMPPRINTFS
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if (icmpprintfs)
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printf("redirect dst %x to %x\n", icp->icmp_ip.ip_dst,
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icp->icmp_gwaddr);
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#endif
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icmpsrc.sin_port = 0;
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if (code == ICMP_REDIRECT_NET || code == ICMP_REDIRECT_TOSNET) {
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icmpsrc.sin_addr =
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in_makeaddr(in_netof(icp->icmp_ip.ip_dst), INADDR_ANY);
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rtredirect((struct sockaddr *)&icmpsrc,
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(struct sockaddr *)&icmpdst, RTF_GATEWAY,
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(struct sockaddr *)&icmpgw);
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icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
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pfctlinput(PRC_REDIRECT_NET,
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(struct sockaddr *)&icmpsrc);
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} else {
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icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
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rtredirect((struct sockaddr *)&icmpsrc,
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(struct sockaddr *)&icmpdst, RTF_GATEWAY | RTF_HOST,
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(struct sockaddr *)&icmpgw);
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pfctlinput(PRC_REDIRECT_HOST,
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(struct sockaddr *)&icmpsrc);
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}
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break;
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/*
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* No kernel processing for the following;
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* just fall through to send to raw listener.
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*/
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case ICMP_ECHOREPLY:
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case ICMP_TSTAMPREPLY:
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case ICMP_IREQREPLY:
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case ICMP_MASKREPLY:
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default:
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break;
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}
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raw:
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icmpsrc.sin_port = 0;
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icmpsrc.sin_addr = ip->ip_src;
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icmpdst.sin_addr = ip->ip_dst;
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raw_input(m, &icmproto, (struct sockaddr *)&icmpsrc,
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(struct sockaddr *)&icmpdst);
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return;
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free:
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m_freem(m);
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}
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/*
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* Reflect the ip packet back to the source
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*/
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icmp_reflect(ip, ifp)
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register struct ip *ip;
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struct ifnet *ifp;
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{
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register struct in_ifaddr *ia;
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struct in_addr t;
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struct mbuf *opts = 0, *ip_srcroute();
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int optlen = (ip->ip_hl << 2) - sizeof(struct ip);
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t = ip->ip_dst;
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ip->ip_dst = ip->ip_src;
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/*
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* If the incoming packet was addressed directly to us,
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* use dst as the src for the reply. Otherwise (broadcast
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* or anonymous), use the address which corresponds
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* to the incoming interface.
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*/
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for (ia = in_ifaddr; ia; ia = ia->ia_next) {
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if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr)
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break;
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if ((ia->ia_ifp->if_flags & IFF_BROADCAST) &&
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t.s_addr == satosin(&ia->ia_broadaddr)->sin_addr.s_addr)
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break;
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}
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if (ia == (struct in_ifaddr *)0)
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ia = ifptoia(ifp);
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if (ia == (struct in_ifaddr *)0)
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ia = in_ifaddr;
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t = IA_SIN(ia)->sin_addr;
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ip->ip_src = t;
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ip->ip_ttl = MAXTTL;
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if (optlen > 0) {
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/*
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* Retrieve any source routing from the incoming packet
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* and strip out other options. Adjust the IP length.
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*/
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opts = ip_srcroute();
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ip->ip_len -= optlen;
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ip_stripoptions(ip, (struct mbuf *)0);
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}
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icmp_send(ip, opts);
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if (opts)
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(void)m_free(opts);
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}
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struct in_ifaddr *
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ifptoia(ifp)
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struct ifnet *ifp;
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{
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register struct in_ifaddr *ia;
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for (ia = in_ifaddr; ia; ia = ia->ia_next)
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if (ia->ia_ifp == ifp)
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return (ia);
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return ((struct in_ifaddr *)0);
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}
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/*
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* Send an icmp packet back to the ip level,
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* after supplying a checksum.
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*/
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icmp_send(ip, opts)
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register struct ip *ip;
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struct mbuf *opts;
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{
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register int hlen;
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register struct icmp *icp;
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register struct mbuf *m;
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m = dtom(ip);
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hlen = ip->ip_hl << 2;
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m->m_off += hlen;
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m->m_len -= hlen;
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icp = mtod(m, struct icmp *);
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icp->icmp_cksum = 0;
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icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen);
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m->m_off -= hlen;
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m->m_len += hlen;
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#ifdef ICMPPRINTFS
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if (icmpprintfs)
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printf("icmp_send dst %x src %x\n", ip->ip_dst, ip->ip_src);
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#endif
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(void) ip_output(m, opts, (struct route *)0, 0);
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}
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# ifdef BERK
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n_time
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iptime()
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{
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struct timeval atv;
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u_long t;
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microtime(&atv);
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t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000;
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return (htonl(t));
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}
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# else BERK
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n_time
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iptime()
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{
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int s = spl6();
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u_long t;
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t = (time.tv_sec % (24*60*60)) * 1000 + time.tv_usec / 1000;
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(void) splx(s);
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return (htonl(t));
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}
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# endif BERK
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/*
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* Written Monday 23rd April 1992 By Darren Reed (avalon@coombs.anu.edu.au)
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* The object of this routine is to return the address of the tcp control
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* block which is described by the source and destination IP number and
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* port. I cant find any routine elsewhere which does this and it is a useful
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* routine to implement (although it should probably be in one of the
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* tcp source modules :-). It is in here because I used it to implement a more
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* more secure and intelligent handling of ICMP errors for TCP connections.
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* -avalon
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*/
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int lookuptcp(tco)
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register struct tcpiphdr *tco;
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{
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#define IPEQUAL(x,y) (!bcmp((char *)(x),(char *)(y),sizeof(struct in_addr)))
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register struct inpcb *inp;
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register struct tcpiphdr *ti = NULL;
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struct tcpcb *tp;
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inp = tcb.inp_next;
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if (inp)
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for (; inp != &tcb; inp = inp->inp_next) {
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if (!(tp = (struct tcpcb *)inp->inp_ppcb))
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continue;
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if (!(ti = tp->t_template))
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continue;
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if (tp->t_state >= TCPS_ESTABLISHED)
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continue;
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if (ti->ti_sport == tco->ti_sport &&
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ti->ti_dport == tco->ti_dport &&
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IPEQUAL(&ti->ti_src, &tco->ti_src) &&
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IPEQUAL(&ti->ti_dst, &tco->ti_dst))
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return (int)(tp);
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}
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return 0;
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}
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