1 /*
2 * Copyright (c) 1982, 1986, 1988, 1993
3 * The Regents of the University of California.
4 * Copyright (c) 2005 Andre Oppermann, Internet Business Solutions AG.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
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.
18 *
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
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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
29 * SUCH DAMAGE.
30 */
31
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD: releng/8.4/sys/netinet/ip_options.c 213947 2010-10-17 08:46:34Z bz $");
34
35 #include "opt_ipstealth.h"
36
37 #include <sys/param.h>
38 #include <sys/systm.h>
39 #include <sys/mbuf.h>
40 #include <sys/domain.h>
41 #include <sys/protosw.h>
42 #include <sys/socket.h>
43 #include <sys/time.h>
44 #include <sys/kernel.h>
45 #include <sys/syslog.h>
46 #include <sys/sysctl.h>
47
48 #include <net/if.h>
49 #include <net/if_types.h>
50 #include <net/if_var.h>
51 #include <net/if_dl.h>
52 #include <net/route.h>
53 #include <net/netisr.h>
54 #include <net/vnet.h>
55
56 #include <netinet/in.h>
57 #include <netinet/in_systm.h>
58 #include <netinet/in_var.h>
59 #include <netinet/ip.h>
60 #include <netinet/in_pcb.h>
61 #include <netinet/ip_var.h>
62 #include <netinet/ip_options.h>
63 #include <netinet/ip_icmp.h>
64 #include <machine/in_cksum.h>
65
66 #include <sys/socketvar.h>
67
68 #include <security/mac/mac_framework.h>
69
70 static int ip_dosourceroute = 0;
71 SYSCTL_INT(_net_inet_ip, IPCTL_SOURCEROUTE, sourceroute, CTLFLAG_RW,
72 &ip_dosourceroute, 0, "Enable forwarding source routed IP packets");
73
74 static int ip_acceptsourceroute = 0;
75 SYSCTL_INT(_net_inet_ip, IPCTL_ACCEPTSOURCEROUTE, accept_sourceroute,
76 CTLFLAG_RW, &ip_acceptsourceroute, 0,
77 "Enable accepting source routed IP packets");
78
79 int ip_doopts = 1; /* 0 = ignore, 1 = process, 2 = reject */
80 SYSCTL_INT(_net_inet_ip, OID_AUTO, process_options, CTLFLAG_RW,
81 &ip_doopts, 0, "Enable IP options processing ([LS]SRR, RR, TS)");
82
83 static void save_rte(struct mbuf *m, u_char *, struct in_addr);
84
85 /*
86 * Do option processing on a datagram, possibly discarding it if bad options
87 * are encountered, or forwarding it if source-routed.
88 *
89 * The pass argument is used when operating in the IPSTEALTH mode to tell
90 * what options to process: [LS]SRR (pass 0) or the others (pass 1). The
91 * reason for as many as two passes is that when doing IPSTEALTH, non-routing
92 * options should be processed only if the packet is for us.
93 *
94 * Returns 1 if packet has been forwarded/freed, 0 if the packet should be
95 * processed further.
96 */
97 int
98 ip_dooptions(struct mbuf *m, int pass)
99 {
100 struct ip *ip = mtod(m, struct ip *);
101 u_char *cp;
102 struct in_ifaddr *ia;
103 int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0;
104 struct in_addr *sin, dst;
105 uint32_t ntime;
106 struct sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET };
107
108 /* Ignore or reject packets with IP options. */
109 if (ip_doopts == 0)
110 return 0;
111 else if (ip_doopts == 2) {
112 type = ICMP_UNREACH;
113 code = ICMP_UNREACH_FILTER_PROHIB;
114 goto bad;
115 }
116
117 dst = ip->ip_dst;
118 cp = (u_char *)(ip + 1);
119 cnt = (ip->ip_hl << 2) - sizeof (struct ip);
120 for (; cnt > 0; cnt -= optlen, cp += optlen) {
121 opt = cp[IPOPT_OPTVAL];
122 if (opt == IPOPT_EOL)
123 break;
124 if (opt == IPOPT_NOP)
125 optlen = 1;
126 else {
127 if (cnt < IPOPT_OLEN + sizeof(*cp)) {
128 code = &cp[IPOPT_OLEN] - (u_char *)ip;
129 goto bad;
130 }
131 optlen = cp[IPOPT_OLEN];
132 if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt) {
133 code = &cp[IPOPT_OLEN] - (u_char *)ip;
134 goto bad;
135 }
136 }
137 switch (opt) {
138
139 default:
140 break;
141
142 /*
143 * Source routing with record. Find interface with current
144 * destination address. If none on this machine then drop if
145 * strictly routed, or do nothing if loosely routed. Record
146 * interface address and bring up next address component. If
147 * strictly routed make sure next address is on directly
148 * accessible net.
149 */
150 case IPOPT_LSRR:
151 case IPOPT_SSRR:
152 #ifdef IPSTEALTH
153 if (V_ipstealth && pass > 0)
154 break;
155 #endif
156 if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
157 code = &cp[IPOPT_OLEN] - (u_char *)ip;
158 goto bad;
159 }
160 if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
161 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
162 goto bad;
163 }
164 ipaddr.sin_addr = ip->ip_dst;
165 if (ifa_ifwithaddr_check((struct sockaddr *)&ipaddr)
166 == 0) {
167 if (opt == IPOPT_SSRR) {
168 type = ICMP_UNREACH;
169 code = ICMP_UNREACH_SRCFAIL;
170 goto bad;
171 }
172 if (!ip_dosourceroute)
173 goto nosourcerouting;
174 /*
175 * Loose routing, and not at next destination
176 * yet; nothing to do except forward.
177 */
178 break;
179 }
180 off--; /* 0 origin */
181 if (off > optlen - (int)sizeof(struct in_addr)) {
182 /*
183 * End of source route. Should be for us.
184 */
185 if (!ip_acceptsourceroute)
186 goto nosourcerouting;
187 save_rte(m, cp, ip->ip_src);
188 break;
189 }
190 #ifdef IPSTEALTH
191 if (V_ipstealth)
192 goto dropit;
193 #endif
194 if (!ip_dosourceroute) {
195 if (V_ipforwarding) {
196 char buf[16]; /* aaa.bbb.ccc.ddd\0 */
197 /*
198 * Acting as a router, so generate
199 * ICMP
200 */
201 nosourcerouting:
202 strcpy(buf, inet_ntoa(ip->ip_dst));
203 log(LOG_WARNING,
204 "attempted source route from %s to %s\n",
205 inet_ntoa(ip->ip_src), buf);
206 type = ICMP_UNREACH;
207 code = ICMP_UNREACH_SRCFAIL;
208 goto bad;
209 } else {
210 /*
211 * Not acting as a router, so
212 * silently drop.
213 */
214 #ifdef IPSTEALTH
215 dropit:
216 #endif
217 IPSTAT_INC(ips_cantforward);
218 m_freem(m);
219 return (1);
220 }
221 }
222
223 /*
224 * locate outgoing interface
225 */
226 (void)memcpy(&ipaddr.sin_addr, cp + off,
227 sizeof(ipaddr.sin_addr));
228
229 if (opt == IPOPT_SSRR) {
230 #define INA struct in_ifaddr *
231 #define SA struct sockaddr *
232 if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == NULL)
233 ia = (INA)ifa_ifwithnet((SA)&ipaddr, 0);
234 } else
235 /* XXX MRT 0 for routing */
236 ia = ip_rtaddr(ipaddr.sin_addr, M_GETFIB(m));
237 if (ia == NULL) {
238 type = ICMP_UNREACH;
239 code = ICMP_UNREACH_SRCFAIL;
240 goto bad;
241 }
242 ip->ip_dst = ipaddr.sin_addr;
243 (void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr),
244 sizeof(struct in_addr));
245 ifa_free(&ia->ia_ifa);
246 cp[IPOPT_OFFSET] += sizeof(struct in_addr);
247 /*
248 * Let ip_intr's mcast routing check handle mcast pkts
249 */
250 forward = !IN_MULTICAST(ntohl(ip->ip_dst.s_addr));
251 break;
252
253 case IPOPT_RR:
254 #ifdef IPSTEALTH
255 if (V_ipstealth && pass == 0)
256 break;
257 #endif
258 if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
259 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
260 goto bad;
261 }
262 if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
263 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
264 goto bad;
265 }
266 /*
267 * If no space remains, ignore.
268 */
269 off--; /* 0 origin */
270 if (off > optlen - (int)sizeof(struct in_addr))
271 break;
272 (void)memcpy(&ipaddr.sin_addr, &ip->ip_dst,
273 sizeof(ipaddr.sin_addr));
274 /*
275 * Locate outgoing interface; if we're the
276 * destination, use the incoming interface (should be
277 * same).
278 */
279 if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == NULL &&
280 (ia = ip_rtaddr(ipaddr.sin_addr, M_GETFIB(m))) == NULL) {
281 type = ICMP_UNREACH;
282 code = ICMP_UNREACH_HOST;
283 goto bad;
284 }
285 (void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr),
286 sizeof(struct in_addr));
287 ifa_free(&ia->ia_ifa);
288 cp[IPOPT_OFFSET] += sizeof(struct in_addr);
289 break;
290
291 case IPOPT_TS:
292 #ifdef IPSTEALTH
293 if (V_ipstealth && pass == 0)
294 break;
295 #endif
296 code = cp - (u_char *)ip;
297 if (optlen < 4 || optlen > 40) {
298 code = &cp[IPOPT_OLEN] - (u_char *)ip;
299 goto bad;
300 }
301 if ((off = cp[IPOPT_OFFSET]) < 5) {
302 code = &cp[IPOPT_OLEN] - (u_char *)ip;
303 goto bad;
304 }
305 if (off > optlen - (int)sizeof(int32_t)) {
306 cp[IPOPT_OFFSET + 1] += (1 << 4);
307 if ((cp[IPOPT_OFFSET + 1] & 0xf0) == 0) {
308 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
309 goto bad;
310 }
311 break;
312 }
313 off--; /* 0 origin */
314 sin = (struct in_addr *)(cp + off);
315 switch (cp[IPOPT_OFFSET + 1] & 0x0f) {
316
317 case IPOPT_TS_TSONLY:
318 break;
319
320 case IPOPT_TS_TSANDADDR:
321 if (off + sizeof(uint32_t) +
322 sizeof(struct in_addr) > optlen) {
323 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
324 goto bad;
325 }
326 ipaddr.sin_addr = dst;
327 ia = (INA)ifaof_ifpforaddr((SA)&ipaddr,
328 m->m_pkthdr.rcvif);
329 if (ia == NULL)
330 continue;
331 (void)memcpy(sin, &IA_SIN(ia)->sin_addr,
332 sizeof(struct in_addr));
333 ifa_free(&ia->ia_ifa);
334 cp[IPOPT_OFFSET] += sizeof(struct in_addr);
335 off += sizeof(struct in_addr);
336 break;
337
338 case IPOPT_TS_PRESPEC:
339 if (off + sizeof(uint32_t) +
340 sizeof(struct in_addr) > optlen) {
341 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
342 goto bad;
343 }
344 (void)memcpy(&ipaddr.sin_addr, sin,
345 sizeof(struct in_addr));
346 if (ifa_ifwithaddr_check((SA)&ipaddr) == 0)
347 continue;
348 cp[IPOPT_OFFSET] += sizeof(struct in_addr);
349 off += sizeof(struct in_addr);
350 break;
351
352 default:
353 code = &cp[IPOPT_OFFSET + 1] - (u_char *)ip;
354 goto bad;
355 }
356 ntime = iptime();
357 (void)memcpy(cp + off, &ntime, sizeof(uint32_t));
358 cp[IPOPT_OFFSET] += sizeof(uint32_t);
359 }
360 }
361 if (forward && V_ipforwarding) {
362 ip_forward(m, 1);
363 return (1);
364 }
365 return (0);
366 bad:
367 icmp_error(m, type, code, 0, 0);
368 IPSTAT_INC(ips_badoptions);
369 return (1);
370 }
371
372 /*
373 * Save incoming source route for use in replies, to be picked up later by
374 * ip_srcroute if the receiver is interested.
375 */
376 static void
377 save_rte(struct mbuf *m, u_char *option, struct in_addr dst)
378 {
379 unsigned olen;
380 struct ipopt_tag *opts;
381
382 opts = (struct ipopt_tag *)m_tag_get(PACKET_TAG_IPOPTIONS,
383 sizeof(struct ipopt_tag), M_NOWAIT);
384 if (opts == NULL)
385 return;
386
387 olen = option[IPOPT_OLEN];
388 if (olen > sizeof(opts->ip_srcrt) - (1 + sizeof(dst))) {
389 m_tag_free((struct m_tag *)opts);
390 return;
391 }
392 bcopy(option, opts->ip_srcrt.srcopt, olen);
393 opts->ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr);
394 opts->ip_srcrt.dst = dst;
395 m_tag_prepend(m, (struct m_tag *)opts);
396 }
397
398 /*
399 * Retrieve incoming source route for use in replies, in the same form used
400 * by setsockopt. The first hop is placed before the options, will be
401 * removed later.
402 */
403 struct mbuf *
404 ip_srcroute(struct mbuf *m0)
405 {
406 struct in_addr *p, *q;
407 struct mbuf *m;
408 struct ipopt_tag *opts;
409
410 opts = (struct ipopt_tag *)m_tag_find(m0, PACKET_TAG_IPOPTIONS, NULL);
411 if (opts == NULL)
412 return (NULL);
413
414 if (opts->ip_nhops == 0)
415 return (NULL);
416 m = m_get(M_DONTWAIT, MT_DATA);
417 if (m == NULL)
418 return (NULL);
419
420 #define OPTSIZ (sizeof(opts->ip_srcrt.nop) + sizeof(opts->ip_srcrt.srcopt))
421
422 /* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */
423 m->m_len = opts->ip_nhops * sizeof(struct in_addr) +
424 sizeof(struct in_addr) + OPTSIZ;
425
426 /*
427 * First, save first hop for return route.
428 */
429 p = &(opts->ip_srcrt.route[opts->ip_nhops - 1]);
430 *(mtod(m, struct in_addr *)) = *p--;
431
432 /*
433 * Copy option fields and padding (nop) to mbuf.
434 */
435 opts->ip_srcrt.nop = IPOPT_NOP;
436 opts->ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF;
437 (void)memcpy(mtod(m, caddr_t) + sizeof(struct in_addr),
438 &(opts->ip_srcrt.nop), OPTSIZ);
439 q = (struct in_addr *)(mtod(m, caddr_t) +
440 sizeof(struct in_addr) + OPTSIZ);
441 #undef OPTSIZ
442 /*
443 * Record return path as an IP source route, reversing the path
444 * (pointers are now aligned).
445 */
446 while (p >= opts->ip_srcrt.route) {
447 *q++ = *p--;
448 }
449 /*
450 * Last hop goes to final destination.
451 */
452 *q = opts->ip_srcrt.dst;
453 m_tag_delete(m0, (struct m_tag *)opts);
454 return (m);
455 }
456
457 /*
458 * Strip out IP options, at higher level protocol in the kernel. Second
459 * argument is buffer to which options will be moved, and return value is
460 * their length.
461 *
462 * XXX should be deleted; last arg currently ignored.
463 */
464 void
465 ip_stripoptions(struct mbuf *m, struct mbuf *mopt)
466 {
467 int i;
468 struct ip *ip = mtod(m, struct ip *);
469 caddr_t opts;
470 int olen;
471
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);
476 m->m_len -= olen;
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;
481 }
482
483 /*
484 * Insert IP options into preformed packet. Adjust IP destination as
485 * required for IP source routing, as indicated by a non-zero in_addr at the
486 * start of the options.
487 *
488 * XXX This routine assumes that the packet has no options in place.
489 */
490 struct mbuf *
491 ip_insertoptions(struct mbuf *m, struct mbuf *opt, int *phlen)
492 {
493 struct ipoption *p = mtod(opt, struct ipoption *);
494 struct mbuf *n;
495 struct ip *ip = mtod(m, struct ip *);
496 unsigned optlen;
497
498 optlen = opt->m_len - sizeof(p->ipopt_dst);
499 if (optlen + ip->ip_len > IP_MAXPACKET) {
500 *phlen = 0;
501 return (m); /* XXX should fail */
502 }
503 if (p->ipopt_dst.s_addr)
504 ip->ip_dst = p->ipopt_dst;
505 if (m->m_flags & M_EXT || m->m_data - optlen < m->m_pktdat) {
506 MGETHDR(n, M_DONTWAIT, MT_DATA);
507 if (n == NULL) {
508 *phlen = 0;
509 return (m);
510 }
511 M_MOVE_PKTHDR(n, m);
512 n->m_pkthdr.rcvif = NULL;
513 n->m_pkthdr.len += optlen;
514 m->m_len -= sizeof(struct ip);
515 m->m_data += sizeof(struct ip);
516 n->m_next = m;
517 m = n;
518 m->m_len = optlen + sizeof(struct ip);
519 m->m_data += max_linkhdr;
520 bcopy(ip, mtod(m, void *), sizeof(struct ip));
521 } else {
522 m->m_data -= optlen;
523 m->m_len += optlen;
524 m->m_pkthdr.len += optlen;
525 bcopy(ip, mtod(m, void *), sizeof(struct ip));
526 }
527 ip = mtod(m, struct ip *);
528 bcopy(p->ipopt_list, ip + 1, optlen);
529 *phlen = sizeof(struct ip) + optlen;
530 ip->ip_v = IPVERSION;
531 ip->ip_hl = *phlen >> 2;
532 ip->ip_len += optlen;
533 return (m);
534 }
535
536 /*
537 * Copy options from ip to jp, omitting those not copied during
538 * fragmentation.
539 */
540 int
541 ip_optcopy(struct ip *ip, struct ip *jp)
542 {
543 u_char *cp, *dp;
544 int opt, optlen, cnt;
545
546 cp = (u_char *)(ip + 1);
547 dp = (u_char *)(jp + 1);
548 cnt = (ip->ip_hl << 2) - sizeof (struct ip);
549 for (; cnt > 0; cnt -= optlen, cp += optlen) {
550 opt = cp[0];
551 if (opt == IPOPT_EOL)
552 break;
553 if (opt == IPOPT_NOP) {
554 /* Preserve for IP mcast tunnel's LSRR alignment. */
555 *dp++ = IPOPT_NOP;
556 optlen = 1;
557 continue;
558 }
559
560 KASSERT(cnt >= IPOPT_OLEN + sizeof(*cp),
561 ("ip_optcopy: malformed ipv4 option"));
562 optlen = cp[IPOPT_OLEN];
563 KASSERT(optlen >= IPOPT_OLEN + sizeof(*cp) && optlen <= cnt,
564 ("ip_optcopy: malformed ipv4 option"));
565
566 /* Bogus lengths should have been caught by ip_dooptions. */
567 if (optlen > cnt)
568 optlen = cnt;
569 if (IPOPT_COPIED(opt)) {
570 bcopy(cp, dp, optlen);
571 dp += optlen;
572 }
573 }
574 for (optlen = dp - (u_char *)(jp+1); optlen & 0x3; optlen++)
575 *dp++ = IPOPT_EOL;
576 return (optlen);
577 }
578
579 /*
580 * Set up IP options in pcb for insertion in output packets. Store in mbuf
581 * with pointer in pcbopt, adding pseudo-option with destination address if
582 * source routed.
583 */
584 int
585 ip_pcbopts(struct inpcb *inp, int optname, struct mbuf *m)
586 {
587 int cnt, optlen;
588 u_char *cp;
589 struct mbuf **pcbopt;
590 u_char opt;
591
592 INP_WLOCK_ASSERT(inp);
593
594 pcbopt = &inp->inp_options;
595
596 /* turn off any old options */
597 if (*pcbopt)
598 (void)m_free(*pcbopt);
599 *pcbopt = 0;
600 if (m == NULL || m->m_len == 0) {
601 /*
602 * Only turning off any previous options.
603 */
604 if (m != NULL)
605 (void)m_free(m);
606 return (0);
607 }
608
609 if (m->m_len % sizeof(int32_t))
610 goto bad;
611 /*
612 * IP first-hop destination address will be stored before actual
613 * options; move other options back and clear it when none present.
614 */
615 if (m->m_data + m->m_len + sizeof(struct in_addr) >= &m->m_dat[MLEN])
616 goto bad;
617 cnt = m->m_len;
618 m->m_len += sizeof(struct in_addr);
619 cp = mtod(m, u_char *) + sizeof(struct in_addr);
620 bcopy(mtod(m, void *), cp, (unsigned)cnt);
621 bzero(mtod(m, void *), sizeof(struct in_addr));
622
623 for (; cnt > 0; cnt -= optlen, cp += optlen) {
624 opt = cp[IPOPT_OPTVAL];
625 if (opt == IPOPT_EOL)
626 break;
627 if (opt == IPOPT_NOP)
628 optlen = 1;
629 else {
630 if (cnt < IPOPT_OLEN + sizeof(*cp))
631 goto bad;
632 optlen = cp[IPOPT_OLEN];
633 if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt)
634 goto bad;
635 }
636 switch (opt) {
637
638 default:
639 break;
640
641 case IPOPT_LSRR:
642 case IPOPT_SSRR:
643 /*
644 * User process specifies route as:
645 *
646 * ->A->B->C->D
647 *
648 * D must be our final destination (but we can't
649 * check that since we may not have connected yet).
650 * A is first hop destination, which doesn't appear
651 * in actual IP option, but is stored before the
652 * options.
653 */
654 /* XXX-BZ PRIV_NETINET_SETHDROPTS? */
655 if (optlen < IPOPT_MINOFF - 1 + sizeof(struct in_addr))
656 goto bad;
657 m->m_len -= sizeof(struct in_addr);
658 cnt -= sizeof(struct in_addr);
659 optlen -= sizeof(struct in_addr);
660 cp[IPOPT_OLEN] = optlen;
661 /*
662 * Move first hop before start of options.
663 */
664 bcopy((caddr_t)&cp[IPOPT_OFFSET+1], mtod(m, caddr_t),
665 sizeof(struct in_addr));
666 /*
667 * Then copy rest of options back
668 * to close up the deleted entry.
669 */
670 bcopy((&cp[IPOPT_OFFSET+1] + sizeof(struct in_addr)),
671 &cp[IPOPT_OFFSET+1],
672 (unsigned)cnt - (IPOPT_MINOFF - 1));
673 break;
674 }
675 }
676 if (m->m_len > MAX_IPOPTLEN + sizeof(struct in_addr))
677 goto bad;
678 *pcbopt = m;
679 return (0);
680
681 bad:
682 (void)m_free(m);
683 return (EINVAL);
684 }
685
686 /*
687 * Check for the presence of the IP Router Alert option [RFC2113]
688 * in the header of an IPv4 datagram.
689 *
690 * This call is not intended for use from the forwarding path; it is here
691 * so that protocol domains may check for the presence of the option.
692 * Given how FreeBSD's IPv4 stack is currently structured, the Router Alert
693 * option does not have much relevance to the implementation, though this
694 * may change in future.
695 * Router alert options SHOULD be passed if running in IPSTEALTH mode and
696 * we are not the endpoint.
697 * Length checks on individual options should already have been peformed
698 * by ip_dooptions() therefore they are folded under INVARIANTS here.
699 *
700 * Return zero if not present or options are invalid, non-zero if present.
701 */
702 int
703 ip_checkrouteralert(struct mbuf *m)
704 {
705 struct ip *ip = mtod(m, struct ip *);
706 u_char *cp;
707 int opt, optlen, cnt, found_ra;
708
709 found_ra = 0;
710 cp = (u_char *)(ip + 1);
711 cnt = (ip->ip_hl << 2) - sizeof (struct ip);
712 for (; cnt > 0; cnt -= optlen, cp += optlen) {
713 opt = cp[IPOPT_OPTVAL];
714 if (opt == IPOPT_EOL)
715 break;
716 if (opt == IPOPT_NOP)
717 optlen = 1;
718 else {
719 #ifdef INVARIANTS
720 if (cnt < IPOPT_OLEN + sizeof(*cp))
721 break;
722 #endif
723 optlen = cp[IPOPT_OLEN];
724 #ifdef INVARIANTS
725 if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt)
726 break;
727 #endif
728 }
729 switch (opt) {
730 case IPOPT_RA:
731 #ifdef INVARIANTS
732 if (optlen != IPOPT_OFFSET + sizeof(uint16_t) ||
733 (*((uint16_t *)&cp[IPOPT_OFFSET]) != 0))
734 break;
735 else
736 #endif
737 found_ra = 1;
738 break;
739 default:
740 break;
741 }
742 }
743
744 return (found_ra);
745 }
Cache object: 8533ff3cdad792e14462fbc69e734914
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