1 /* $NetBSD: mpls_ttl.c,v 1.15 2018/12/27 14:03:55 maxv Exp $ */
2
3 /*
4 * Copyright (c) 2010 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Public Access Networks Corporation ("Panix"). It was developed under
9 * contract to Panix by Eric Haszlakiewicz and Thor Lancelot Simon.
10 *
11 * This code is derived from software contributed to The NetBSD Foundation
12 * by Jason R. Thorpe of Zembu Labs, Inc.
13 *
14 * This code is derived from software contributed to The NetBSD Foundation
15 * by Mihai Chelaru <kefren@NetBSD.org>
16 *
17 * Redistribution and use in source and binary forms, with or without
18 * modification, are permitted provided that the following conditions
19 * are met:
20 * 1. Redistributions of source code must retain the above copyright
21 * notice, this list of conditions and the following disclaimer.
22 * 2. Redistributions in binary form must reproduce the above copyright
23 * notice, this list of conditions and the following disclaimer in the
24 * documentation and/or other materials provided with the distribution.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
27 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
28 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
29 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
30 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
31 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
32 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
33 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
34 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
35 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
36 * POSSIBILITY OF SUCH DAMAGE.
37 */
38
39 /*
40 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
41 * All rights reserved.
42 *
43 * Redistribution and use in source and binary forms, with or without
44 * modification, are permitted provided that the following conditions
45 * are met:
46 * 1. Redistributions of source code must retain the above copyright
47 * notice, this list of conditions and the following disclaimer.
48 * 2. Redistributions in binary form must reproduce the above copyright
49 * notice, this list of conditions and the following disclaimer in the
50 * documentation and/or other materials provided with the distribution.
51 * 3. Neither the name of the project nor the names of its contributors
52 * may be used to endorse or promote products derived from this software
53 * without specific prior written permission.
54 *
55 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
56 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
57 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
58 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
59 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
60 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
61 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
62 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
63 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
64 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
65 * SUCH DAMAGE.
66 */
67
68 /*
69 * Copyright (c) 1982, 1986, 1988, 1993
70 * The Regents of the University of California. All rights reserved.
71 *
72 * Redistribution and use in source and binary forms, with or without
73 * modification, are permitted provided that the following conditions
74 * are met:
75 * 1. Redistributions of source code must retain the above copyright
76 * notice, this list of conditions and the following disclaimer.
77 * 2. Redistributions in binary form must reproduce the above copyright
78 * notice, this list of conditions and the following disclaimer in the
79 * documentation and/or other materials provided with the distribution.
80 * 3. Neither the name of the University nor the names of its contributors
81 * may be used to endorse or promote products derived from this software
82 * without specific prior written permission.
83 *
84 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
85 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
86 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
87 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
88 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
89 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
90 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
91 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
92 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
93 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
94 * SUCH DAMAGE.
95 *
96 * @(#)ip_icmp.c 8.2 (Berkeley) 1/4/94
97 */
98
99 #include <sys/cdefs.h>
100 __KERNEL_RCSID(0, "$NetBSD: mpls_ttl.c,v 1.15 2018/12/27 14:03:55 maxv Exp $");
101
102 #ifdef _KERNEL_OPT
103 #include "opt_inet.h"
104 #include "opt_mpls.h"
105 #endif
106
107 #include <sys/param.h>
108 #include <sys/malloc.h>
109 #include <sys/mbuf.h>
110 #include <sys/errno.h>
111 #include <sys/socket.h>
112 #include <sys/systm.h>
113
114 #include <net/if.h>
115 #include <net/if_dl.h>
116
117 #include <netinet/in.h>
118 #include <netinet/in_systm.h>
119 #include <netinet/ip.h>
120 #include <netinet/ip_icmp.h>
121 #include <netinet/icmp_private.h>
122 #include <netinet/icmp_var.h>
123
124 #include <netmpls/mpls.h>
125 #include <netmpls/mpls_var.h>
126
127 #ifdef INET
128
129 /* in netinet/ip_icmp.c */
130 extern int icmpreturndatabytes;
131
132 /* ICMP Extensions */
133 #define MPLS_STACK_ENTRY_CLASS 1
134 #define MPLS_STACK_ENTRY_C_TYPE 1
135
136 struct mpls_extension {
137 struct icmp_ext_hdr cmn_hdr;
138 struct icmp_ext_obj_hdr obj_hdr;
139 union mpls_shim ms;
140 } __packed;
141
142 static void mpls_icmp_error(struct mbuf *, int, int, n_long, int,
143 union mpls_shim *);
144 static struct mbuf *ip4_check(struct mbuf *);
145
146 /*
147 * Send an ICMP Extended error message. References: RFC4884 and RFC4950.
148 *
149 * XXX: This code is inspired from icmp_error(), and should really be merged
150 * into it. icmp_error() should handle ICMP Extended error messages.
151 *
152 * XXX: It is called only for ICMP_TIMXCEED_INTRANS but code is too general.
153 *
154 * XXX: We're not setting the 'length' field of the Extended ICMP header.
155 * According to RFC4884, we are in 'non-compliant' mode. Moreover, we're
156 * not computing the checksum of the Extended ICMP header.
157 */
158 static void
mpls_icmp_error(struct mbuf * n,int type,int code,n_long dest,int destmtu,union mpls_shim * shim)159 mpls_icmp_error(struct mbuf *n, int type, int code, n_long dest,
160 int destmtu, union mpls_shim *shim)
161 {
162 struct ip *oip = mtod(n, struct ip *), *nip;
163 unsigned oiplen = oip->ip_hl << 2;
164 struct icmp *icp;
165 struct mbuf *m;
166 unsigned icmplen, mblen, packetlen;
167 struct mpls_extension mpls_icmp_ext;
168
169 memset(&mpls_icmp_ext, 0, sizeof(mpls_icmp_ext));
170 mpls_icmp_ext.cmn_hdr.version = ICMP_EXT_VERSION;
171 mpls_icmp_ext.cmn_hdr.checksum = 0; /* XXX */
172
173 mpls_icmp_ext.obj_hdr.length = htons(sizeof(union mpls_shim) +
174 sizeof(struct icmp_ext_obj_hdr));
175 mpls_icmp_ext.obj_hdr.class_num = MPLS_STACK_ENTRY_CLASS;
176 mpls_icmp_ext.obj_hdr.c_type = MPLS_STACK_ENTRY_C_TYPE;
177
178 mpls_icmp_ext.ms.s_addr = shim->s_addr;
179
180 if (type != ICMP_REDIRECT)
181 ICMP_STATINC(ICMP_STAT_ERROR);
182
183 /*
184 * Don't send error if the original packet was encrypted.
185 * Don't send error if not the first fragment of message.
186 * Don't error if the old packet protocol was ICMP
187 * error message, only known informational types.
188 */
189 if (n->m_flags & M_DECRYPTED)
190 goto freeit;
191 if (oip->ip_off &~ htons(IP_MF|IP_DF))
192 goto freeit;
193 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
194 n->m_len >= oiplen + ICMP_MINLEN &&
195 !ICMP_INFOTYPE(((struct icmp *)((char *)oip + oiplen))->icmp_type))
196 {
197 ICMP_STATINC(ICMP_STAT_OLDICMP);
198 goto freeit;
199 }
200
201 /* Don't send error in response to a multicast or broadcast packet */
202 if (n->m_flags & (M_BCAST|M_MCAST))
203 goto freeit;
204
205 /*
206 * First, do a rate limitation check.
207 */
208 if (icmp_ratelimit(&oip->ip_src, type, code))
209 /* XXX stats */
210 goto freeit;
211
212 /*
213 * Now, formulate icmp message
214 */
215 icmplen = uimin(ICMP_EXT_OFFSET, ntohs(oip->ip_len));
216
217 /*
218 * Defend against mbuf chains shorter than oip->ip_len - oiplen:
219 */
220 mblen = 0;
221 for (m = n; m && (mblen < icmplen); m = m->m_next)
222 mblen += m->m_len;
223 icmplen = uimin(mblen, icmplen);
224
225 packetlen = sizeof(struct ip) + offsetof(struct icmp, icmp_ip) +
226 ICMP_EXT_OFFSET + sizeof(mpls_icmp_ext);
227
228 /*
229 * As we are not required to return everything we have,
230 * we return whatever we can return at ease.
231 *
232 * Note that ICMP datagrams longer than 576 octets are out of spec
233 * according to RFC1812; the limit on icmpreturndatabytes below in
234 * icmp_sysctl will keep things below that limit.
235 */
236
237 KASSERT(packetlen <= MCLBYTES);
238
239 m = m_gethdr(M_DONTWAIT, MT_HEADER);
240 if (m && (packetlen > MHLEN)) {
241 MCLGET(m, M_DONTWAIT);
242 if ((m->m_flags & M_EXT) == 0) {
243 m_freem(m);
244 m = NULL;
245 }
246 }
247 if (m == NULL)
248 goto freeit;
249
250 MCLAIM(m, n->m_owner);
251 m->m_len = packetlen;
252 if ((m->m_flags & M_EXT) == 0)
253 m_align(m, m->m_len);
254 m->m_data += sizeof(struct ip);
255 m->m_len -= sizeof(struct ip);
256
257 icp = mtod(m, struct icmp *);
258 if ((u_int)type > ICMP_MAXTYPE)
259 panic("icmp error (mpls_ttl)");
260 ICMP_STATINC(ICMP_STAT_OUTHIST + type);
261 icp->icmp_type = type;
262 if (type == ICMP_REDIRECT)
263 icp->icmp_gwaddr.s_addr = dest;
264 else {
265 icp->icmp_void = 0;
266 /*
267 * The following assignments assume an overlay with the
268 * zeroed icmp_void field.
269 */
270 if (type == ICMP_PARAMPROB) {
271 icp->icmp_pptr = code;
272 code = 0;
273 } else if (type == ICMP_UNREACH &&
274 code == ICMP_UNREACH_NEEDFRAG && destmtu)
275 icp->icmp_nextmtu = htons(destmtu);
276 }
277
278 icp->icmp_code = code;
279
280 memset(&icp->icmp_ip, 0, ICMP_EXT_OFFSET);
281 m_copydata(n, 0, icmplen, (char *)&icp->icmp_ip);
282
283 /* Append the extension structure */
284 memcpy(((char*)&icp->icmp_ip) + ICMP_EXT_OFFSET,
285 &mpls_icmp_ext, sizeof(mpls_icmp_ext));
286
287 /*
288 * Now, copy old ip header (without options)
289 * in front of icmp message.
290 */
291 if ((m->m_flags & M_EXT) == 0 &&
292 m->m_data - sizeof(struct ip) < m->m_pktdat)
293 panic("icmp len");
294 m->m_data -= sizeof(struct ip);
295 m->m_len += sizeof(struct ip);
296 m->m_pkthdr.len = m->m_len;
297 m_copy_rcvif(m, n);
298 nip = mtod(m, struct ip *);
299 /* ip_v set in ip_output */
300 nip->ip_hl = sizeof(struct ip) >> 2;
301 nip->ip_tos = 0;
302 nip->ip_len = htons(m->m_len);
303 /* ip_id set in ip_output */
304 nip->ip_off = htons(0);
305 /* ip_ttl set in icmp_reflect */
306 nip->ip_p = IPPROTO_ICMP;
307 nip->ip_src = oip->ip_src;
308 nip->ip_dst = oip->ip_dst;
309 icmp_reflect(m);
310
311 freeit:
312 m_freem(n);
313 }
314
315 static struct mbuf *
ip4_check(struct mbuf * m)316 ip4_check(struct mbuf *m)
317 {
318 struct ip *iph;
319 int hlen, len;
320
321 if (m->m_len < sizeof(struct ip) &&
322 (m = m_pullup(m, sizeof(struct ip))) == NULL)
323 return NULL;
324
325 iph = mtod(m, struct ip *);
326
327 if (iph->ip_v != IPVERSION)
328 goto freeit;
329 hlen = iph->ip_hl << 2;
330 if (hlen < sizeof(struct ip))
331 goto freeit;
332 if (hlen > m->m_len) {
333 if ((m = m_pullup(m, hlen)) == NULL)
334 return NULL;
335 iph = mtod(m, struct ip *);
336 }
337
338 /*
339 * RFC1122: packets with a multicast source address are
340 * not allowed.
341 * RFC1122: 127/8 must not appear on wire.
342 */
343 if (IN_MULTICAST(iph->ip_src.s_addr) ||
344 (ntohl(iph->ip_dst.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET ||
345 (ntohl(iph->ip_src.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET ||
346 in_cksum(m, hlen) != 0)
347 goto freeit;
348
349 len = ntohs(iph->ip_len);
350 if (len < hlen || m->m_pkthdr.len < len)
351 goto freeit;
352
353 return m;
354
355 freeit:
356 m_freem(m);
357 return NULL;
358 }
359 #endif /* INET */
360
361 struct mbuf *
mpls_ttl_dec(struct mbuf * m)362 mpls_ttl_dec(struct mbuf *m)
363 {
364 union mpls_shim *mshim;
365 #ifdef INET
366 union mpls_shim top_shim, bos_shim;
367 #endif
368
369 if (__predict_false(m->m_len < sizeof(union mpls_shim) &&
370 (m = m_pullup(m, sizeof(union mpls_shim))) == NULL))
371 return NULL;
372 mshim = mtod(m, union mpls_shim *);
373 mshim->s_addr = ntohl(mshim->s_addr);
374 mshim->shim.ttl--;
375
376 if (mshim->shim.ttl == 0) {
377 if (!mpls_icmp_respond) {
378 m_freem(m);
379 return NULL;
380 }
381
382 #ifdef INET
383 /*
384 * Shim ttl exceeded. Send back ICMP type 11 code 0.
385 */
386 bos_shim.s_addr = mshim->s_addr;
387 top_shim.s_addr = htonl(mshim->s_addr);
388 m_adj(m, sizeof(union mpls_shim));
389
390 /* Goto BOS */
391 while (bos_shim.shim.bos == 0) {
392 if (m->m_len < sizeof(union mpls_shim) &&
393 (m = m_pullup(m, sizeof(union mpls_shim))) == NULL) {
394 m_freem(m);
395 return NULL;
396 }
397 bos_shim.s_addr = ntohl(mtod(m, union mpls_shim *)->s_addr);
398 m_adj(m, sizeof(union mpls_shim));
399 }
400
401 if ((m = ip4_check(m)) != NULL)
402 mpls_icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS,
403 0, 0, &top_shim);
404 #else
405 m_freem(m);
406 #endif
407 return NULL;
408 }
409
410 mshim->s_addr = htonl(mshim->s_addr);
411
412 return m;
413 }
414