ip_options.c revision 213832
1171169Smlaier/*
2171169Smlaier * Copyright (c) 1982, 1986, 1988, 1993
3171169Smlaier *      The Regents of the University of California.
4171169Smlaier * Copyright (c) 2005 Andre Oppermann, Internet Business Solutions AG.
5171169Smlaier * All rights reserved.
6171169Smlaier *
7171169Smlaier * Redistribution and use in source and binary forms, with or without
8171169Smlaier * modification, are permitted provided that the following conditions
9171169Smlaier * are met:
10171169Smlaier * 1. Redistributions of source code must retain the above copyright
11171169Smlaier *    notice, this list of conditions and the following disclaimer.
12171169Smlaier * 2. Redistributions in binary form must reproduce the above copyright
13171169Smlaier *    notice, this list of conditions and the following disclaimer in the
14171169Smlaier *    documentation and/or other materials provided with the distribution.
15171169Smlaier * 4. Neither the name of the University nor the names of its contributors
16171169Smlaier *    may be used to endorse or promote products derived from this software
17171169Smlaier *    without specific prior written permission.
18171169Smlaier *
19171169Smlaier * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20171169Smlaier * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21171169Smlaier * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22171169Smlaier * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23171169Smlaier * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24171169Smlaier * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25171169Smlaier * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26171169Smlaier * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27171169Smlaier * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28171169Smlaier * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29171169Smlaier * SUCH DAMAGE.
30171169Smlaier */
31171169Smlaier
32171169Smlaier#include <sys/cdefs.h>
33171169Smlaier__FBSDID("$FreeBSD: head/sys/netinet/ip_options.c 213832 2010-10-14 12:32:49Z bz $");
34171169Smlaier
35171169Smlaier#include "opt_ipstealth.h"
36171169Smlaier
37171169Smlaier#include <sys/param.h>
38171169Smlaier#include <sys/systm.h>
39171169Smlaier#include <sys/mbuf.h>
40171169Smlaier#include <sys/domain.h>
41171169Smlaier#include <sys/protosw.h>
42171169Smlaier#include <sys/socket.h>
43171169Smlaier#include <sys/time.h>
44171169Smlaier#include <sys/kernel.h>
45171169Smlaier#include <sys/syslog.h>
46171169Smlaier#include <sys/sysctl.h>
47171169Smlaier
48171169Smlaier#include <net/if.h>
49171169Smlaier#include <net/if_types.h>
50171169Smlaier#include <net/if_var.h>
51171169Smlaier#include <net/if_dl.h>
52171169Smlaier#include <net/route.h>
53171169Smlaier#include <net/netisr.h>
54171169Smlaier#include <net/vnet.h>
55171169Smlaier
56171169Smlaier#include <netinet/in.h>
57171169Smlaier#include <netinet/in_systm.h>
58171169Smlaier#include <netinet/in_var.h>
59171169Smlaier#include <netinet/ip.h>
60171169Smlaier#include <netinet/in_pcb.h>
61171169Smlaier#include <netinet/ip_var.h>
62171169Smlaier#include <netinet/ip_options.h>
63171169Smlaier#include <netinet/ip_icmp.h>
64171169Smlaier#include <machine/in_cksum.h>
65171169Smlaier
66171169Smlaier#include <sys/socketvar.h>
67171169Smlaier
68171169Smlaierstatic int	ip_dosourceroute = 0;
69171169SmlaierSYSCTL_INT(_net_inet_ip, IPCTL_SOURCEROUTE, sourceroute, CTLFLAG_RW,
70171169Smlaier    &ip_dosourceroute, 0, "Enable forwarding source routed IP packets");
71171169Smlaier
72171169Smlaierstatic int	ip_acceptsourceroute = 0;
73171169SmlaierSYSCTL_INT(_net_inet_ip, IPCTL_ACCEPTSOURCEROUTE, accept_sourceroute,
74171169Smlaier    CTLFLAG_RW, &ip_acceptsourceroute, 0,
75171169Smlaier    "Enable accepting source routed IP packets");
76171169Smlaier
77171169Smlaierint		ip_doopts = 1;	/* 0 = ignore, 1 = process, 2 = reject */
78171169SmlaierSYSCTL_INT(_net_inet_ip, OID_AUTO, process_options, CTLFLAG_RW,
79171169Smlaier    &ip_doopts, 0, "Enable IP options processing ([LS]SRR, RR, TS)");
80171169Smlaier
81171169Smlaierstatic void	save_rte(struct mbuf *m, u_char *, struct in_addr);
82171169Smlaier
83171169Smlaier/*
84171169Smlaier * Do option processing on a datagram, possibly discarding it if bad options
85171169Smlaier * are encountered, or forwarding it if source-routed.
86171169Smlaier *
87171169Smlaier * The pass argument is used when operating in the IPSTEALTH mode to tell
88171169Smlaier * what options to process: [LS]SRR (pass 0) or the others (pass 1).  The
89171169Smlaier * reason for as many as two passes is that when doing IPSTEALTH, non-routing
90171169Smlaier * options should be processed only if the packet is for us.
91171169Smlaier *
92171169Smlaier * Returns 1 if packet has been forwarded/freed, 0 if the packet should be
93171169Smlaier * processed further.
94171169Smlaier */
95171169Smlaierint
96171169Smlaierip_dooptions(struct mbuf *m, int pass)
97171169Smlaier{
98171169Smlaier	struct ip *ip = mtod(m, struct ip *);
99171169Smlaier	u_char *cp;
100171169Smlaier	struct in_ifaddr *ia;
101171169Smlaier	int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0;
102171169Smlaier	struct in_addr *sin, dst;
103171169Smlaier	uint32_t ntime;
104171169Smlaier	struct	sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET };
105171169Smlaier
106171169Smlaier	/* Ignore or reject packets with IP options. */
107171169Smlaier	if (ip_doopts == 0)
108171169Smlaier		return 0;
109171169Smlaier	else if (ip_doopts == 2) {
110171169Smlaier		type = ICMP_UNREACH;
111171169Smlaier		code = ICMP_UNREACH_FILTER_PROHIB;
112171169Smlaier		goto bad;
113171169Smlaier	}
114171169Smlaier
115171169Smlaier	dst = ip->ip_dst;
116171169Smlaier	cp = (u_char *)(ip + 1);
117171169Smlaier	cnt = (ip->ip_hl << 2) - sizeof (struct ip);
118171169Smlaier	for (; cnt > 0; cnt -= optlen, cp += optlen) {
119171169Smlaier		opt = cp[IPOPT_OPTVAL];
120171169Smlaier		if (opt == IPOPT_EOL)
121171169Smlaier			break;
122171169Smlaier		if (opt == IPOPT_NOP)
123171169Smlaier			optlen = 1;
124171169Smlaier		else {
125171169Smlaier			if (cnt < IPOPT_OLEN + sizeof(*cp)) {
126171169Smlaier				code = &cp[IPOPT_OLEN] - (u_char *)ip;
127171169Smlaier				goto bad;
128171169Smlaier			}
129171169Smlaier			optlen = cp[IPOPT_OLEN];
130171169Smlaier			if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt) {
131171169Smlaier				code = &cp[IPOPT_OLEN] - (u_char *)ip;
132171169Smlaier				goto bad;
133171169Smlaier			}
134171169Smlaier		}
135171169Smlaier		switch (opt) {
136171169Smlaier
137171169Smlaier		default:
138171169Smlaier			break;
139171169Smlaier
140171169Smlaier		/*
141171169Smlaier		 * Source routing with record.  Find interface with current
142171169Smlaier		 * destination address.  If none on this machine then drop if
143171169Smlaier		 * strictly routed, or do nothing if loosely routed.  Record
144171169Smlaier		 * interface address and bring up next address component.  If
145171169Smlaier		 * strictly routed make sure next address is on directly
146171169Smlaier		 * accessible net.
147171169Smlaier		 */
148171169Smlaier		case IPOPT_LSRR:
149171169Smlaier		case IPOPT_SSRR:
150171169Smlaier#ifdef IPSTEALTH
151171169Smlaier			if (V_ipstealth && pass > 0)
152171169Smlaier				break;
153171169Smlaier#endif
154171169Smlaier			if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
155171169Smlaier				code = &cp[IPOPT_OLEN] - (u_char *)ip;
156171169Smlaier				goto bad;
157171169Smlaier			}
158171169Smlaier			if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
159171169Smlaier				code = &cp[IPOPT_OFFSET] - (u_char *)ip;
160171169Smlaier				goto bad;
161171169Smlaier			}
162171169Smlaier			ipaddr.sin_addr = ip->ip_dst;
163171169Smlaier			if (ifa_ifwithaddr_check((struct sockaddr *)&ipaddr)
164171169Smlaier			    == 0) {
165171169Smlaier				if (opt == IPOPT_SSRR) {
166171169Smlaier					type = ICMP_UNREACH;
167171169Smlaier					code = ICMP_UNREACH_SRCFAIL;
168171169Smlaier					goto bad;
169171169Smlaier				}
170171169Smlaier				if (!ip_dosourceroute)
171171169Smlaier					goto nosourcerouting;
172171169Smlaier				/*
173171169Smlaier				 * Loose routing, and not at next destination
174171169Smlaier				 * yet; nothing to do except forward.
175171169Smlaier				 */
176171169Smlaier				break;
177171169Smlaier			}
178171169Smlaier			off--;			/* 0 origin */
179171169Smlaier			if (off > optlen - (int)sizeof(struct in_addr)) {
180171169Smlaier				/*
181171169Smlaier				 * End of source route.  Should be for us.
182171169Smlaier				 */
183171169Smlaier				if (!ip_acceptsourceroute)
184171169Smlaier					goto nosourcerouting;
185171169Smlaier				save_rte(m, cp, ip->ip_src);
186171169Smlaier				break;
187171169Smlaier			}
188171169Smlaier#ifdef IPSTEALTH
189171169Smlaier			if (V_ipstealth)
190171169Smlaier				goto dropit;
191171169Smlaier#endif
192171169Smlaier			if (!ip_dosourceroute) {
193171169Smlaier				if (V_ipforwarding) {
194171169Smlaier					char buf[16]; /* aaa.bbb.ccc.ddd\0 */
195171169Smlaier					/*
196171169Smlaier					 * Acting as a router, so generate
197171169Smlaier					 * ICMP
198171169Smlaier					 */
199171169Smlaiernosourcerouting:
200171169Smlaier					strcpy(buf, inet_ntoa(ip->ip_dst));
201171169Smlaier					log(LOG_WARNING,
202171169Smlaier					    "attempted source route from %s to %s\n",
203171169Smlaier					    inet_ntoa(ip->ip_src), buf);
204171169Smlaier					type = ICMP_UNREACH;
205171169Smlaier					code = ICMP_UNREACH_SRCFAIL;
206171169Smlaier					goto bad;
207171169Smlaier				} else {
208171169Smlaier					/*
209171169Smlaier					 * Not acting as a router, so
210171169Smlaier					 * silently drop.
211171169Smlaier					 */
212171169Smlaier#ifdef IPSTEALTH
213171169Smlaierdropit:
214171169Smlaier#endif
215171169Smlaier					IPSTAT_INC(ips_cantforward);
216171169Smlaier					m_freem(m);
217171169Smlaier					return (1);
218171169Smlaier				}
219171169Smlaier			}
220171169Smlaier
221171169Smlaier			/*
222171169Smlaier			 * locate outgoing interface
223171169Smlaier			 */
224171169Smlaier			(void)memcpy(&ipaddr.sin_addr, cp + off,
225171169Smlaier			    sizeof(ipaddr.sin_addr));
226171169Smlaier
227171169Smlaier			if (opt == IPOPT_SSRR) {
228171169Smlaier#define	INA	struct in_ifaddr *
229171169Smlaier#define	SA	struct sockaddr *
230171169Smlaier			    if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == NULL)
231171169Smlaier				    ia = (INA)ifa_ifwithnet((SA)&ipaddr, 0);
232171169Smlaier			} else
233171169Smlaier/* XXX MRT 0 for routing */
234171169Smlaier				ia = ip_rtaddr(ipaddr.sin_addr, M_GETFIB(m));
235171169Smlaier			if (ia == NULL) {
236171169Smlaier				type = ICMP_UNREACH;
237171169Smlaier				code = ICMP_UNREACH_SRCFAIL;
238171169Smlaier				goto bad;
239171169Smlaier			}
240171169Smlaier			ip->ip_dst = ipaddr.sin_addr;
241171169Smlaier			(void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr),
242171169Smlaier			    sizeof(struct in_addr));
243171169Smlaier			ifa_free(&ia->ia_ifa);
244171169Smlaier			cp[IPOPT_OFFSET] += sizeof(struct in_addr);
245171169Smlaier			/*
246171169Smlaier			 * Let ip_intr's mcast routing check handle mcast pkts
247171169Smlaier			 */
248171169Smlaier			forward = !IN_MULTICAST(ntohl(ip->ip_dst.s_addr));
249171169Smlaier			break;
250171169Smlaier
251171169Smlaier		case IPOPT_RR:
252171169Smlaier#ifdef IPSTEALTH
253171169Smlaier			if (V_ipstealth && pass == 0)
254171169Smlaier				break;
255171169Smlaier#endif
256171169Smlaier			if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
257171169Smlaier				code = &cp[IPOPT_OFFSET] - (u_char *)ip;
258171169Smlaier				goto bad;
259171169Smlaier			}
260171169Smlaier			if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
261171169Smlaier				code = &cp[IPOPT_OFFSET] - (u_char *)ip;
262171169Smlaier				goto bad;
263171169Smlaier			}
264171169Smlaier			/*
265171169Smlaier			 * If no space remains, ignore.
266171169Smlaier			 */
267171169Smlaier			off--;			/* 0 origin */
268171169Smlaier			if (off > optlen - (int)sizeof(struct in_addr))
269171169Smlaier				break;
270171169Smlaier			(void)memcpy(&ipaddr.sin_addr, &ip->ip_dst,
271171169Smlaier			    sizeof(ipaddr.sin_addr));
272171169Smlaier			/*
273171169Smlaier			 * Locate outgoing interface; if we're the
274171169Smlaier			 * destination, use the incoming interface (should be
275171169Smlaier			 * same).
276171169Smlaier			 */
277171169Smlaier			if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == NULL &&
278171169Smlaier			    (ia = ip_rtaddr(ipaddr.sin_addr, M_GETFIB(m))) == NULL) {
279171169Smlaier				type = ICMP_UNREACH;
280171169Smlaier				code = ICMP_UNREACH_HOST;
281171169Smlaier				goto bad;
282171169Smlaier			}
283171169Smlaier			(void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr),
284171169Smlaier			    sizeof(struct in_addr));
285171169Smlaier			ifa_free(&ia->ia_ifa);
286171169Smlaier			cp[IPOPT_OFFSET] += sizeof(struct in_addr);
287171169Smlaier			break;
288171169Smlaier
289171169Smlaier		case IPOPT_TS:
290171169Smlaier#ifdef IPSTEALTH
291171169Smlaier			if (V_ipstealth && pass == 0)
292171169Smlaier				break;
293171169Smlaier#endif
294171169Smlaier			code = cp - (u_char *)ip;
295171169Smlaier			if (optlen < 4 || optlen > 40) {
296171169Smlaier				code = &cp[IPOPT_OLEN] - (u_char *)ip;
297171169Smlaier				goto bad;
298171169Smlaier			}
299171169Smlaier			if ((off = cp[IPOPT_OFFSET]) < 5) {
300171169Smlaier				code = &cp[IPOPT_OLEN] - (u_char *)ip;
301171169Smlaier				goto bad;
302171169Smlaier			}
303171169Smlaier			if (off > optlen - (int)sizeof(int32_t)) {
304171169Smlaier				cp[IPOPT_OFFSET + 1] += (1 << 4);
305171169Smlaier				if ((cp[IPOPT_OFFSET + 1] & 0xf0) == 0) {
306171169Smlaier					code = &cp[IPOPT_OFFSET] - (u_char *)ip;
307171169Smlaier					goto bad;
308171169Smlaier				}
309171169Smlaier				break;
310171169Smlaier			}
311171169Smlaier			off--;				/* 0 origin */
312171169Smlaier			sin = (struct in_addr *)(cp + off);
313171169Smlaier			switch (cp[IPOPT_OFFSET + 1] & 0x0f) {
314171169Smlaier
315171169Smlaier			case IPOPT_TS_TSONLY:
316171169Smlaier				break;
317171169Smlaier
318171169Smlaier			case IPOPT_TS_TSANDADDR:
319171169Smlaier				if (off + sizeof(uint32_t) +
320171169Smlaier				    sizeof(struct in_addr) > optlen) {
321171169Smlaier					code = &cp[IPOPT_OFFSET] - (u_char *)ip;
322171169Smlaier					goto bad;
323171169Smlaier				}
324171169Smlaier				ipaddr.sin_addr = dst;
325171169Smlaier				ia = (INA)ifaof_ifpforaddr((SA)&ipaddr,
326171169Smlaier							    m->m_pkthdr.rcvif);
327171169Smlaier				if (ia == NULL)
328171169Smlaier					continue;
329171169Smlaier				(void)memcpy(sin, &IA_SIN(ia)->sin_addr,
330171169Smlaier				    sizeof(struct in_addr));
331171169Smlaier				ifa_free(&ia->ia_ifa);
332171169Smlaier				cp[IPOPT_OFFSET] += sizeof(struct in_addr);
333171169Smlaier				off += sizeof(struct in_addr);
334171169Smlaier				break;
335171169Smlaier
336171169Smlaier			case IPOPT_TS_PRESPEC:
337171169Smlaier				if (off + sizeof(uint32_t) +
338171169Smlaier				    sizeof(struct in_addr) > optlen) {
339171169Smlaier					code = &cp[IPOPT_OFFSET] - (u_char *)ip;
340171169Smlaier					goto bad;
341171169Smlaier				}
342171169Smlaier				(void)memcpy(&ipaddr.sin_addr, sin,
343171169Smlaier				    sizeof(struct in_addr));
344171169Smlaier				if (ifa_ifwithaddr_check((SA)&ipaddr) == 0)
345171169Smlaier					continue;
346171169Smlaier				cp[IPOPT_OFFSET] += sizeof(struct in_addr);
347171169Smlaier				off += sizeof(struct in_addr);
348171169Smlaier				break;
349171169Smlaier
350171169Smlaier			default:
351171169Smlaier				code = &cp[IPOPT_OFFSET + 1] - (u_char *)ip;
352171169Smlaier				goto bad;
353171169Smlaier			}
354171169Smlaier			ntime = iptime();
355171169Smlaier			(void)memcpy(cp + off, &ntime, sizeof(uint32_t));
356171169Smlaier			cp[IPOPT_OFFSET] += sizeof(uint32_t);
357171169Smlaier		}
358171169Smlaier	}
359171169Smlaier	if (forward && V_ipforwarding) {
360171169Smlaier		ip_forward(m, 1);
361171169Smlaier		return (1);
362171169Smlaier	}
363171169Smlaier	return (0);
364171169Smlaierbad:
365171169Smlaier	icmp_error(m, type, code, 0, 0);
366171169Smlaier	IPSTAT_INC(ips_badoptions);
367171169Smlaier	return (1);
368171169Smlaier}
369171169Smlaier
370171169Smlaier/*
371171169Smlaier * Save incoming source route for use in replies, to be picked up later by
372171169Smlaier * ip_srcroute if the receiver is interested.
373171169Smlaier */
374171169Smlaierstatic void
375171169Smlaiersave_rte(struct mbuf *m, u_char *option, struct in_addr dst)
376171169Smlaier{
377171169Smlaier	unsigned olen;
378171169Smlaier	struct ipopt_tag *opts;
379171169Smlaier
380171169Smlaier	opts = (struct ipopt_tag *)m_tag_get(PACKET_TAG_IPOPTIONS,
381171169Smlaier	    sizeof(struct ipopt_tag), M_NOWAIT);
382171169Smlaier	if (opts == NULL)
383171169Smlaier		return;
384171169Smlaier
385171169Smlaier	olen = option[IPOPT_OLEN];
386171169Smlaier	if (olen > sizeof(opts->ip_srcrt) - (1 + sizeof(dst))) {
387171169Smlaier		m_tag_free((struct m_tag *)opts);
388171169Smlaier		return;
389171169Smlaier	}
390171169Smlaier	bcopy(option, opts->ip_srcrt.srcopt, olen);
391171169Smlaier	opts->ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr);
392171169Smlaier	opts->ip_srcrt.dst = dst;
393171169Smlaier	m_tag_prepend(m, (struct m_tag *)opts);
394171169Smlaier}
395171169Smlaier
396171169Smlaier/*
397171169Smlaier * Retrieve incoming source route for use in replies, in the same form used
398171169Smlaier * by setsockopt.  The first hop is placed before the options, will be
399171169Smlaier * removed later.
400171169Smlaier */
401171169Smlaierstruct mbuf *
402171169Smlaierip_srcroute(struct mbuf *m0)
403171169Smlaier{
404171169Smlaier	struct in_addr *p, *q;
405171169Smlaier	struct mbuf *m;
406171169Smlaier	struct ipopt_tag *opts;
407171169Smlaier
408171169Smlaier	opts = (struct ipopt_tag *)m_tag_find(m0, PACKET_TAG_IPOPTIONS, NULL);
409171169Smlaier	if (opts == NULL)
410171169Smlaier		return (NULL);
411171169Smlaier
412171169Smlaier	if (opts->ip_nhops == 0)
413171169Smlaier		return (NULL);
414171169Smlaier	m = m_get(M_DONTWAIT, MT_DATA);
415171169Smlaier	if (m == NULL)
416171169Smlaier		return (NULL);
417171169Smlaier
418171169Smlaier#define OPTSIZ	(sizeof(opts->ip_srcrt.nop) + sizeof(opts->ip_srcrt.srcopt))
419171169Smlaier
420171169Smlaier	/* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */
421171169Smlaier	m->m_len = opts->ip_nhops * sizeof(struct in_addr) +
422171169Smlaier	    sizeof(struct in_addr) + OPTSIZ;
423171169Smlaier
424171169Smlaier	/*
425171169Smlaier	 * First, save first hop for return route.
426171169Smlaier	 */
427171169Smlaier	p = &(opts->ip_srcrt.route[opts->ip_nhops - 1]);
428171169Smlaier	*(mtod(m, struct in_addr *)) = *p--;
429171169Smlaier
430171169Smlaier	/*
431171169Smlaier	 * Copy option fields and padding (nop) to mbuf.
432171169Smlaier	 */
433171169Smlaier	opts->ip_srcrt.nop = IPOPT_NOP;
434171169Smlaier	opts->ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF;
435171169Smlaier	(void)memcpy(mtod(m, caddr_t) + sizeof(struct in_addr),
436171169Smlaier	    &(opts->ip_srcrt.nop), OPTSIZ);
437171169Smlaier	q = (struct in_addr *)(mtod(m, caddr_t) +
438171169Smlaier	    sizeof(struct in_addr) + OPTSIZ);
439171169Smlaier#undef OPTSIZ
440171169Smlaier	/*
441171169Smlaier	 * Record return path as an IP source route, reversing the path
442171169Smlaier	 * (pointers are now aligned).
443171169Smlaier	 */
444171169Smlaier	while (p >= opts->ip_srcrt.route) {
445171169Smlaier		*q++ = *p--;
446171169Smlaier	}
447171169Smlaier	/*
448171169Smlaier	 * Last hop goes to final destination.
449171169Smlaier	 */
450171169Smlaier	*q = opts->ip_srcrt.dst;
451171169Smlaier	m_tag_delete(m0, (struct m_tag *)opts);
452171169Smlaier	return (m);
453171169Smlaier}
454171169Smlaier
455171169Smlaier/*
456171169Smlaier * Strip out IP options, at higher level protocol in the kernel.  Second
457 * argument is buffer to which options will be moved, and return value is
458 * their length.
459 *
460 * XXX should be deleted; last arg currently ignored.
461 */
462void
463ip_stripoptions(struct mbuf *m, struct mbuf *mopt)
464{
465	int i;
466	struct ip *ip = mtod(m, struct ip *);
467	caddr_t opts;
468	int olen;
469
470	olen = (ip->ip_hl << 2) - sizeof (struct ip);
471	opts = (caddr_t)(ip + 1);
472	i = m->m_len - (sizeof (struct ip) + olen);
473	bcopy(opts + olen, opts, (unsigned)i);
474	m->m_len -= olen;
475	if (m->m_flags & M_PKTHDR)
476		m->m_pkthdr.len -= olen;
477	ip->ip_v = IPVERSION;
478	ip->ip_hl = sizeof(struct ip) >> 2;
479}
480
481/*
482 * Insert IP options into preformed packet.  Adjust IP destination as
483 * required for IP source routing, as indicated by a non-zero in_addr at the
484 * start of the options.
485 *
486 * XXX This routine assumes that the packet has no options in place.
487 */
488struct mbuf *
489ip_insertoptions(struct mbuf *m, struct mbuf *opt, int *phlen)
490{
491	struct ipoption *p = mtod(opt, struct ipoption *);
492	struct mbuf *n;
493	struct ip *ip = mtod(m, struct ip *);
494	unsigned optlen;
495
496	optlen = opt->m_len - sizeof(p->ipopt_dst);
497	if (optlen + ip->ip_len > IP_MAXPACKET) {
498		*phlen = 0;
499		return (m);		/* XXX should fail */
500	}
501	if (p->ipopt_dst.s_addr)
502		ip->ip_dst = p->ipopt_dst;
503	if (m->m_flags & M_EXT || m->m_data - optlen < m->m_pktdat) {
504		MGETHDR(n, M_DONTWAIT, MT_DATA);
505		if (n == NULL) {
506			*phlen = 0;
507			return (m);
508		}
509		M_MOVE_PKTHDR(n, m);
510		n->m_pkthdr.rcvif = NULL;
511		n->m_pkthdr.len += optlen;
512		m->m_len -= sizeof(struct ip);
513		m->m_data += sizeof(struct ip);
514		n->m_next = m;
515		m = n;
516		m->m_len = optlen + sizeof(struct ip);
517		m->m_data += max_linkhdr;
518		bcopy(ip, mtod(m, void *), sizeof(struct ip));
519	} else {
520		m->m_data -= optlen;
521		m->m_len += optlen;
522		m->m_pkthdr.len += optlen;
523		bcopy(ip, mtod(m, void *), sizeof(struct ip));
524	}
525	ip = mtod(m, struct ip *);
526	bcopy(p->ipopt_list, ip + 1, optlen);
527	*phlen = sizeof(struct ip) + optlen;
528	ip->ip_v = IPVERSION;
529	ip->ip_hl = *phlen >> 2;
530	ip->ip_len += optlen;
531	return (m);
532}
533
534/*
535 * Copy options from ip to jp, omitting those not copied during
536 * fragmentation.
537 */
538int
539ip_optcopy(struct ip *ip, struct ip *jp)
540{
541	u_char *cp, *dp;
542	int opt, optlen, cnt;
543
544	cp = (u_char *)(ip + 1);
545	dp = (u_char *)(jp + 1);
546	cnt = (ip->ip_hl << 2) - sizeof (struct ip);
547	for (; cnt > 0; cnt -= optlen, cp += optlen) {
548		opt = cp[0];
549		if (opt == IPOPT_EOL)
550			break;
551		if (opt == IPOPT_NOP) {
552			/* Preserve for IP mcast tunnel's LSRR alignment. */
553			*dp++ = IPOPT_NOP;
554			optlen = 1;
555			continue;
556		}
557
558		KASSERT(cnt >= IPOPT_OLEN + sizeof(*cp),
559		    ("ip_optcopy: malformed ipv4 option"));
560		optlen = cp[IPOPT_OLEN];
561		KASSERT(optlen >= IPOPT_OLEN + sizeof(*cp) && optlen <= cnt,
562		    ("ip_optcopy: malformed ipv4 option"));
563
564		/* Bogus lengths should have been caught by ip_dooptions. */
565		if (optlen > cnt)
566			optlen = cnt;
567		if (IPOPT_COPIED(opt)) {
568			bcopy(cp, dp, optlen);
569			dp += optlen;
570		}
571	}
572	for (optlen = dp - (u_char *)(jp+1); optlen & 0x3; optlen++)
573		*dp++ = IPOPT_EOL;
574	return (optlen);
575}
576
577/*
578 * Set up IP options in pcb for insertion in output packets.  Store in mbuf
579 * with pointer in pcbopt, adding pseudo-option with destination address if
580 * source routed.
581 */
582int
583ip_pcbopts(struct inpcb *inp, int optname, struct mbuf *m)
584{
585	int cnt, optlen;
586	u_char *cp;
587	struct mbuf **pcbopt;
588	u_char opt;
589
590	INP_WLOCK_ASSERT(inp);
591
592	pcbopt = &inp->inp_options;
593
594	/* turn off any old options */
595	if (*pcbopt)
596		(void)m_free(*pcbopt);
597	*pcbopt = 0;
598	if (m == NULL || m->m_len == 0) {
599		/*
600		 * Only turning off any previous options.
601		 */
602		if (m != NULL)
603			(void)m_free(m);
604		return (0);
605	}
606
607	if (m->m_len % sizeof(int32_t))
608		goto bad;
609	/*
610	 * IP first-hop destination address will be stored before actual
611	 * options; move other options back and clear it when none present.
612	 */
613	if (m->m_data + m->m_len + sizeof(struct in_addr) >= &m->m_dat[MLEN])
614		goto bad;
615	cnt = m->m_len;
616	m->m_len += sizeof(struct in_addr);
617	cp = mtod(m, u_char *) + sizeof(struct in_addr);
618	bcopy(mtod(m, void *), cp, (unsigned)cnt);
619	bzero(mtod(m, void *), sizeof(struct in_addr));
620
621	for (; cnt > 0; cnt -= optlen, cp += optlen) {
622		opt = cp[IPOPT_OPTVAL];
623		if (opt == IPOPT_EOL)
624			break;
625		if (opt == IPOPT_NOP)
626			optlen = 1;
627		else {
628			if (cnt < IPOPT_OLEN + sizeof(*cp))
629				goto bad;
630			optlen = cp[IPOPT_OLEN];
631			if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt)
632				goto bad;
633		}
634		switch (opt) {
635
636		default:
637			break;
638
639		case IPOPT_LSRR:
640		case IPOPT_SSRR:
641			/*
642			 * User process specifies route as:
643			 *
644			 *	->A->B->C->D
645			 *
646			 * D must be our final destination (but we can't
647			 * check that since we may not have connected yet).
648			 * A is first hop destination, which doesn't appear
649			 * in actual IP option, but is stored before the
650			 * options.
651			 */
652			/* XXX-BZ PRIV_NETINET_SETHDROPTS? */
653			if (optlen < IPOPT_MINOFF - 1 + sizeof(struct in_addr))
654				goto bad;
655			m->m_len -= sizeof(struct in_addr);
656			cnt -= sizeof(struct in_addr);
657			optlen -= sizeof(struct in_addr);
658			cp[IPOPT_OLEN] = optlen;
659			/*
660			 * Move first hop before start of options.
661			 */
662			bcopy((caddr_t)&cp[IPOPT_OFFSET+1], mtod(m, caddr_t),
663			    sizeof(struct in_addr));
664			/*
665			 * Then copy rest of options back
666			 * to close up the deleted entry.
667			 */
668			bcopy((&cp[IPOPT_OFFSET+1] + sizeof(struct in_addr)),
669			    &cp[IPOPT_OFFSET+1],
670			    (unsigned)cnt - (IPOPT_MINOFF - 1));
671			break;
672		}
673	}
674	if (m->m_len > MAX_IPOPTLEN + sizeof(struct in_addr))
675		goto bad;
676	*pcbopt = m;
677	return (0);
678
679bad:
680	(void)m_free(m);
681	return (EINVAL);
682}
683
684/*
685 * Check for the presence of the IP Router Alert option [RFC2113]
686 * in the header of an IPv4 datagram.
687 *
688 * This call is not intended for use from the forwarding path; it is here
689 * so that protocol domains may check for the presence of the option.
690 * Given how FreeBSD's IPv4 stack is currently structured, the Router Alert
691 * option does not have much relevance to the implementation, though this
692 * may change in future.
693 * Router alert options SHOULD be passed if running in IPSTEALTH mode and
694 * we are not the endpoint.
695 * Length checks on individual options should already have been peformed
696 * by ip_dooptions() therefore they are folded under INVARIANTS here.
697 *
698 * Return zero if not present or options are invalid, non-zero if present.
699 */
700int
701ip_checkrouteralert(struct mbuf *m)
702{
703	struct ip *ip = mtod(m, struct ip *);
704	u_char *cp;
705	int opt, optlen, cnt, found_ra;
706
707	found_ra = 0;
708	cp = (u_char *)(ip + 1);
709	cnt = (ip->ip_hl << 2) - sizeof (struct ip);
710	for (; cnt > 0; cnt -= optlen, cp += optlen) {
711		opt = cp[IPOPT_OPTVAL];
712		if (opt == IPOPT_EOL)
713			break;
714		if (opt == IPOPT_NOP)
715			optlen = 1;
716		else {
717#ifdef INVARIANTS
718			if (cnt < IPOPT_OLEN + sizeof(*cp))
719				break;
720#endif
721			optlen = cp[IPOPT_OLEN];
722#ifdef INVARIANTS
723			if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt)
724				break;
725#endif
726		}
727		switch (opt) {
728		case IPOPT_RA:
729#ifdef INVARIANTS
730			if (optlen != IPOPT_OFFSET + sizeof(uint16_t) ||
731			    (*((uint16_t *)&cp[IPOPT_OFFSET]) != 0))
732			    break;
733			else
734#endif
735			found_ra = 1;
736			break;
737		default:
738			break;
739		}
740	}
741
742	return (found_ra);
743}
744