2 * Copyright (c) 1982, 1986, 1988, 1993
3 * The Regents of the University of California. All rights reserved.
5 * Andre Oppermann, Internet Business Solutions AG. All right reserved.
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 4. Neither the name of the University nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 #include "opt_ipstealth.h"
37 #include <sys/param.h>
38 #include <sys/systm.h>
41 /* #include <sys/malloc.h> */
42 #include <sys/domain.h>
43 #include <sys/protosw.h>
44 #include <sys/socket.h>
46 #include <sys/kernel.h>
47 #include <sys/syslog.h>
48 #include <sys/sysctl.h>
51 #include <net/if_types.h>
52 #include <net/if_var.h>
53 #include <net/if_dl.h>
54 #include <net/route.h>
55 #include <net/netisr.h>
57 #include <netinet/in.h>
58 #include <netinet/in_systm.h>
59 #include <netinet/in_var.h>
60 #include <netinet/ip.h>
61 #include <netinet/in_pcb.h>
62 #include <netinet/ip_var.h>
63 #include <netinet/ip_options.h>
64 #include <netinet/ip_icmp.h>
65 #include <machine/in_cksum.h>
67 #include <sys/socketvar.h>
69 static int ip_dosourceroute = 0;
70 SYSCTL_INT(_net_inet_ip, IPCTL_SOURCEROUTE, sourceroute, CTLFLAG_RW,
71 &ip_dosourceroute, 0, "Enable forwarding source routed IP packets");
73 static int ip_acceptsourceroute = 0;
74 SYSCTL_INT(_net_inet_ip, IPCTL_ACCEPTSOURCEROUTE, accept_sourceroute,
75 CTLFLAG_RW, &ip_acceptsourceroute, 0,
76 "Enable accepting source routed IP packets");
78 int ip_doopts = 1; /* 0 = ignore, 1 = process, 2 = reject */
79 SYSCTL_INT(_net_inet_ip, OID_AUTO, process_options, CTLFLAG_RW,
80 &ip_doopts, 0, "Enable IP options processing ([LS]SRR, RR, TS)");
82 static void save_rte(struct mbuf *m, u_char *, struct in_addr);
85 * Do option processing on a datagram,
86 * possibly discarding it if bad options are encountered,
87 * or forwarding it if source-routed.
88 * The pass argument is used when operating in the IPSTEALTH
89 * mode to tell what options to process:
90 * [LS]SRR (pass 0) or the others (pass 1).
91 * The reason for as many as two passes is that when doing IPSTEALTH,
92 * non-routing options should be processed only if the packet is for us.
93 * Returns 1 if packet has been forwarded/freed,
94 * 0 if the packet should be processed further.
97 ip_dooptions(struct mbuf *m, int pass)
99 struct ip *ip = mtod(m, struct ip *);
101 struct in_ifaddr *ia;
102 int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0;
103 struct in_addr *sin, dst;
105 struct sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET };
107 /* ignore or reject packets with IP options */
110 else if (ip_doopts == 2) {
112 code = ICMP_UNREACH_FILTER_PROHIB;
117 cp = (u_char *)(ip + 1);
118 cnt = (ip->ip_hl << 2) - sizeof (struct ip);
119 for (; cnt > 0; cnt -= optlen, cp += optlen) {
120 opt = cp[IPOPT_OPTVAL];
121 if (opt == IPOPT_EOL)
123 if (opt == IPOPT_NOP)
126 if (cnt < IPOPT_OLEN + sizeof(*cp)) {
127 code = &cp[IPOPT_OLEN] - (u_char *)ip;
130 optlen = cp[IPOPT_OLEN];
131 if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt) {
132 code = &cp[IPOPT_OLEN] - (u_char *)ip;
142 * Source routing with record.
143 * Find interface with current destination address.
144 * If none on this machine then drop if strictly routed,
145 * or do nothing if loosely routed.
146 * Record interface address and bring up next address
147 * component. If strictly routed make sure next
148 * address is on directly accessible net.
153 if (ipstealth && pass > 0)
156 if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
157 code = &cp[IPOPT_OLEN] - (u_char *)ip;
160 if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
161 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
164 ipaddr.sin_addr = ip->ip_dst;
165 ia = (struct in_ifaddr *)
166 ifa_ifwithaddr((struct sockaddr *)&ipaddr);
168 if (opt == IPOPT_SSRR) {
170 code = ICMP_UNREACH_SRCFAIL;
173 if (!ip_dosourceroute)
174 goto nosourcerouting;
176 * Loose routing, and not at next destination
177 * yet; nothing to do except forward.
181 off--; /* 0 origin */
182 if (off > optlen - (int)sizeof(struct in_addr)) {
184 * End of source route. Should be for us.
186 if (!ip_acceptsourceroute)
187 goto nosourcerouting;
188 save_rte(m, cp, ip->ip_src);
195 if (!ip_dosourceroute) {
197 char buf[16]; /* aaa.bbb.ccc.ddd\0 */
199 * Acting as a router, so generate ICMP
202 strcpy(buf, inet_ntoa(ip->ip_dst));
204 "attempted source route from %s to %s\n",
205 inet_ntoa(ip->ip_src), buf);
207 code = ICMP_UNREACH_SRCFAIL;
211 * Not acting as a router, so silently drop.
216 ipstat.ips_cantforward++;
223 * locate outgoing interface
225 (void)memcpy(&ipaddr.sin_addr, cp + off,
226 sizeof(ipaddr.sin_addr));
228 if (opt == IPOPT_SSRR) {
229 #define INA struct in_ifaddr *
230 #define SA struct sockaddr *
231 if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == NULL)
232 ia = (INA)ifa_ifwithnet((SA)&ipaddr);
234 ia = ip_rtaddr(ipaddr.sin_addr);
237 code = ICMP_UNREACH_SRCFAIL;
240 ip->ip_dst = ipaddr.sin_addr;
241 (void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr),
242 sizeof(struct in_addr));
243 cp[IPOPT_OFFSET] += sizeof(struct in_addr);
245 * Let ip_intr's mcast routing check handle mcast pkts
247 forward = !IN_MULTICAST(ntohl(ip->ip_dst.s_addr));
252 if (ipstealth && pass == 0)
255 if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
256 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
259 if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
260 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
264 * If no space remains, ignore.
266 off--; /* 0 origin */
267 if (off > optlen - (int)sizeof(struct in_addr))
269 (void)memcpy(&ipaddr.sin_addr, &ip->ip_dst,
270 sizeof(ipaddr.sin_addr));
272 * locate outgoing interface; if we're the destination,
273 * use the incoming interface (should be same).
275 if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == NULL &&
276 (ia = ip_rtaddr(ipaddr.sin_addr)) == NULL) {
278 code = ICMP_UNREACH_HOST;
281 (void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr),
282 sizeof(struct in_addr));
283 cp[IPOPT_OFFSET] += sizeof(struct in_addr);
288 if (ipstealth && pass == 0)
291 code = cp - (u_char *)ip;
292 if (optlen < 4 || optlen > 40) {
293 code = &cp[IPOPT_OLEN] - (u_char *)ip;
296 if ((off = cp[IPOPT_OFFSET]) < 5) {
297 code = &cp[IPOPT_OLEN] - (u_char *)ip;
300 if (off > optlen - (int)sizeof(int32_t)) {
301 cp[IPOPT_OFFSET + 1] += (1 << 4);
302 if ((cp[IPOPT_OFFSET + 1] & 0xf0) == 0) {
303 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
308 off--; /* 0 origin */
309 sin = (struct in_addr *)(cp + off);
310 switch (cp[IPOPT_OFFSET + 1] & 0x0f) {
312 case IPOPT_TS_TSONLY:
315 case IPOPT_TS_TSANDADDR:
316 if (off + sizeof(n_time) +
317 sizeof(struct in_addr) > optlen) {
318 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
321 ipaddr.sin_addr = dst;
322 ia = (INA)ifaof_ifpforaddr((SA)&ipaddr,
326 (void)memcpy(sin, &IA_SIN(ia)->sin_addr,
327 sizeof(struct in_addr));
328 cp[IPOPT_OFFSET] += sizeof(struct in_addr);
329 off += sizeof(struct in_addr);
332 case IPOPT_TS_PRESPEC:
333 if (off + sizeof(n_time) +
334 sizeof(struct in_addr) > optlen) {
335 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
338 (void)memcpy(&ipaddr.sin_addr, sin,
339 sizeof(struct in_addr));
340 if (ifa_ifwithaddr((SA)&ipaddr) == NULL)
342 cp[IPOPT_OFFSET] += sizeof(struct in_addr);
343 off += sizeof(struct in_addr);
347 code = &cp[IPOPT_OFFSET + 1] - (u_char *)ip;
351 (void)memcpy(cp + off, &ntime, sizeof(n_time));
352 cp[IPOPT_OFFSET] += sizeof(n_time);
355 if (forward && ipforwarding) {
361 icmp_error(m, type, code, 0, 0);
362 ipstat.ips_badoptions++;
367 * Save incoming source route for use in replies,
368 * to be picked up later by ip_srcroute if the receiver is interested.
371 save_rte(m, option, dst)
377 struct ipopt_tag *opts;
379 opts = (struct ipopt_tag *)m_tag_get(PACKET_TAG_IPOPTIONS,
380 sizeof(struct ipopt_tag), M_NOWAIT);
384 olen = option[IPOPT_OLEN];
385 if (olen > sizeof(opts->ip_srcrt) - (1 + sizeof(dst))) {
386 m_tag_free((struct m_tag *)opts);
389 bcopy(option, opts->ip_srcrt.srcopt, olen);
390 opts->ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr);
391 opts->ip_srcrt.dst = dst;
392 m_tag_prepend(m, (struct m_tag *)opts);
396 * Retrieve incoming source route for use in replies,
397 * in the same form used by setsockopt.
398 * The first hop is placed before the options, will be removed later.
404 register struct in_addr *p, *q;
405 register struct mbuf *m;
406 struct ipopt_tag *opts;
408 opts = (struct ipopt_tag *)m_tag_find(m0, PACKET_TAG_IPOPTIONS, NULL);
412 if (opts->ip_nhops == 0)
414 m = m_get(M_DONTWAIT, MT_DATA);
418 #define OPTSIZ (sizeof(opts->ip_srcrt.nop) + sizeof(opts->ip_srcrt.srcopt))
420 /* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */
421 m->m_len = opts->ip_nhops * sizeof(struct in_addr) +
422 sizeof(struct in_addr) + OPTSIZ;
425 * First save first hop for return route
427 p = &(opts->ip_srcrt.route[opts->ip_nhops - 1]);
428 *(mtod(m, struct in_addr *)) = *p--;
431 * Copy option fields and padding (nop) to mbuf.
433 opts->ip_srcrt.nop = IPOPT_NOP;
434 opts->ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF;
435 (void)memcpy(mtod(m, caddr_t) + sizeof(struct in_addr),
436 &(opts->ip_srcrt.nop), OPTSIZ);
437 q = (struct in_addr *)(mtod(m, caddr_t) +
438 sizeof(struct in_addr) + OPTSIZ);
441 * Record return path as an IP source route,
442 * reversing the path (pointers are now aligned).
444 while (p >= opts->ip_srcrt.route) {
448 * Last hop goes to final destination.
450 *q = opts->ip_srcrt.dst;
451 m_tag_delete(m0, (struct m_tag *)opts);
456 * Strip out IP options, at higher
457 * level protocol in the kernel.
458 * Second argument is buffer to which options
459 * will be moved, and return value is their length.
460 * XXX should be deleted; last arg currently ignored.
463 ip_stripoptions(m, mopt)
464 register struct mbuf *m;
468 struct ip *ip = mtod(m, struct ip *);
469 register caddr_t opts;
472 olen = (ip->ip_hl << 2) - sizeof (struct ip);
473 opts = (caddr_t)(ip + 1);
474 i = m->m_len - (sizeof (struct ip) + olen);
475 bcopy(opts + olen, opts, (unsigned)i);
477 if (m->m_flags & M_PKTHDR)
478 m->m_pkthdr.len -= olen;
479 ip->ip_v = IPVERSION;
480 ip->ip_hl = sizeof(struct ip) >> 2;
484 * Insert IP options into preformed packet.
485 * Adjust IP destination as required for IP source routing,
486 * as indicated by a non-zero in_addr at the start of the options.
488 * XXX This routine assumes that the packet has no options in place.
491 ip_insertoptions(m, opt, phlen)
492 register struct mbuf *m;
496 register struct ipoption *p = mtod(opt, struct ipoption *);
498 register struct ip *ip = mtod(m, struct ip *);
501 optlen = opt->m_len - sizeof(p->ipopt_dst);
502 if (optlen + ip->ip_len > IP_MAXPACKET) {
504 return (m); /* XXX should fail */
506 if (p->ipopt_dst.s_addr)
507 ip->ip_dst = p->ipopt_dst;
508 if (m->m_flags & M_EXT || m->m_data - optlen < m->m_pktdat) {
509 MGETHDR(n, M_DONTWAIT, MT_DATA);
515 n->m_pkthdr.rcvif = NULL;
519 n->m_pkthdr.len += optlen;
520 m->m_len -= sizeof(struct ip);
521 m->m_data += sizeof(struct ip);
524 m->m_len = optlen + sizeof(struct ip);
525 m->m_data += max_linkhdr;
526 bcopy(ip, mtod(m, void *), sizeof(struct ip));
530 m->m_pkthdr.len += optlen;
531 bcopy(ip, mtod(m, void *), sizeof(struct ip));
533 ip = mtod(m, struct ip *);
534 bcopy(p->ipopt_list, ip + 1, optlen);
535 *phlen = sizeof(struct ip) + optlen;
536 ip->ip_v = IPVERSION;
537 ip->ip_hl = *phlen >> 2;
538 ip->ip_len += optlen;
543 * Copy options from ip to jp,
544 * omitting those not copied during fragmentation.
550 register u_char *cp, *dp;
551 int opt, optlen, cnt;
553 cp = (u_char *)(ip + 1);
554 dp = (u_char *)(jp + 1);
555 cnt = (ip->ip_hl << 2) - sizeof (struct ip);
556 for (; cnt > 0; cnt -= optlen, cp += optlen) {
558 if (opt == IPOPT_EOL)
560 if (opt == IPOPT_NOP) {
561 /* Preserve for IP mcast tunnel's LSRR alignment. */
567 KASSERT(cnt >= IPOPT_OLEN + sizeof(*cp),
568 ("ip_optcopy: malformed ipv4 option"));
569 optlen = cp[IPOPT_OLEN];
570 KASSERT(optlen >= IPOPT_OLEN + sizeof(*cp) && optlen <= cnt,
571 ("ip_optcopy: malformed ipv4 option"));
573 /* bogus lengths should have been caught by ip_dooptions */
576 if (IPOPT_COPIED(opt)) {
577 bcopy(cp, dp, optlen);
581 for (optlen = dp - (u_char *)(jp+1); optlen & 0x3; optlen++)
587 * Set up IP options in pcb for insertion in output packets.
588 * Store in mbuf with pointer in pcbopt, adding pseudo-option
589 * with destination address if source routed.
592 ip_pcbopts(struct inpcb *inp, int optname, struct mbuf *m)
594 register int cnt, optlen;
596 struct mbuf **pcbopt;
599 INP_LOCK_ASSERT(inp);
601 pcbopt = &inp->inp_options;
603 /* turn off any old options */
605 (void)m_free(*pcbopt);
607 if (m == NULL || m->m_len == 0) {
609 * Only turning off any previous options.
616 if (m->m_len % sizeof(int32_t))
619 * IP first-hop destination address will be stored before
620 * actual options; move other options back
621 * and clear it when none present.
623 if (m->m_data + m->m_len + sizeof(struct in_addr) >= &m->m_dat[MLEN])
626 m->m_len += sizeof(struct in_addr);
627 cp = mtod(m, u_char *) + sizeof(struct in_addr);
628 bcopy(mtod(m, void *), cp, (unsigned)cnt);
629 bzero(mtod(m, void *), sizeof(struct in_addr));
631 for (; cnt > 0; cnt -= optlen, cp += optlen) {
632 opt = cp[IPOPT_OPTVAL];
633 if (opt == IPOPT_EOL)
635 if (opt == IPOPT_NOP)
638 if (cnt < IPOPT_OLEN + sizeof(*cp))
640 optlen = cp[IPOPT_OLEN];
641 if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt)
652 * user process specifies route as:
654 * D must be our final destination (but we can't
655 * check that since we may not have connected yet).
656 * A is first hop destination, which doesn't appear in
657 * actual IP option, but is stored before the options.
659 if (optlen < IPOPT_MINOFF - 1 + sizeof(struct in_addr))
661 m->m_len -= sizeof(struct in_addr);
662 cnt -= sizeof(struct in_addr);
663 optlen -= sizeof(struct in_addr);
664 cp[IPOPT_OLEN] = optlen;
666 * Move first hop before start of options.
668 bcopy((caddr_t)&cp[IPOPT_OFFSET+1], mtod(m, caddr_t),
669 sizeof(struct in_addr));
671 * Then copy rest of options back
672 * to close up the deleted entry.
674 bcopy((&cp[IPOPT_OFFSET+1] + sizeof(struct in_addr)),
676 (unsigned)cnt - (IPOPT_MINOFF - 1));
680 if (m->m_len > MAX_IPOPTLEN + sizeof(struct in_addr))