xref: /openssh-portable/addrmatch.c (revision 1a66079c)
1 /*	$OpenBSD: addrmatch.c,v 1.14 2018/07/31 03:07:24 djm Exp $ */
2 
3 /*
4  * Copyright (c) 2004-2008 Damien Miller <djm@mindrot.org>
5  *
6  * Permission to use, copy, modify, and distribute this software for any
7  * purpose with or without fee is hereby granted, provided that the above
8  * copyright notice and this permission notice appear in all copies.
9  *
10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17  */
18 
19 #include "includes.h"
20 
21 #include <sys/types.h>
22 #include <sys/socket.h>
23 #include <netinet/in.h>
24 #include <arpa/inet.h>
25 
26 #include <netdb.h>
27 #include <string.h>
28 #include <stdlib.h>
29 #include <stdio.h>
30 #include <stdarg.h>
31 
32 #include "match.h"
33 #include "log.h"
34 
35 struct xaddr {
36 	sa_family_t	af;
37 	union {
38 		struct in_addr		v4;
39 		struct in6_addr		v6;
40 		u_int8_t		addr8[16];
41 		u_int32_t		addr32[4];
42 	} xa;		    /* 128-bit address */
43 	u_int32_t	scope_id;	/* iface scope id for v6 */
44 #define v4	xa.v4
45 #define v6	xa.v6
46 #define addr8	xa.addr8
47 #define addr32	xa.addr32
48 };
49 
50 static int
addr_unicast_masklen(int af)51 addr_unicast_masklen(int af)
52 {
53 	switch (af) {
54 	case AF_INET:
55 		return 32;
56 	case AF_INET6:
57 		return 128;
58 	default:
59 		return -1;
60 	}
61 }
62 
63 static inline int
masklen_valid(int af,u_int masklen)64 masklen_valid(int af, u_int masklen)
65 {
66 	switch (af) {
67 	case AF_INET:
68 		return masklen <= 32 ? 0 : -1;
69 	case AF_INET6:
70 		return masklen <= 128 ? 0 : -1;
71 	default:
72 		return -1;
73 	}
74 }
75 
76 /*
77  * Convert struct sockaddr to struct xaddr
78  * Returns 0 on success, -1 on failure.
79  */
80 static int
addr_sa_to_xaddr(struct sockaddr * sa,socklen_t slen,struct xaddr * xa)81 addr_sa_to_xaddr(struct sockaddr *sa, socklen_t slen, struct xaddr *xa)
82 {
83 	struct sockaddr_in *in4 = (struct sockaddr_in *)sa;
84 	struct sockaddr_in6 *in6 = (struct sockaddr_in6 *)sa;
85 
86 	memset(xa, '\0', sizeof(*xa));
87 
88 	switch (sa->sa_family) {
89 	case AF_INET:
90 		if (slen < (socklen_t)sizeof(*in4))
91 			return -1;
92 		xa->af = AF_INET;
93 		memcpy(&xa->v4, &in4->sin_addr, sizeof(xa->v4));
94 		break;
95 	case AF_INET6:
96 		if (slen < (socklen_t)sizeof(*in6))
97 			return -1;
98 		xa->af = AF_INET6;
99 		memcpy(&xa->v6, &in6->sin6_addr, sizeof(xa->v6));
100 #ifdef HAVE_STRUCT_SOCKADDR_IN6_SIN6_SCOPE_ID
101 		xa->scope_id = in6->sin6_scope_id;
102 #endif
103 		break;
104 	default:
105 		return -1;
106 	}
107 
108 	return 0;
109 }
110 
111 /*
112  * Calculate a netmask of length 'l' for address family 'af' and
113  * store it in 'n'.
114  * Returns 0 on success, -1 on failure.
115  */
116 static int
addr_netmask(int af,u_int l,struct xaddr * n)117 addr_netmask(int af, u_int l, struct xaddr *n)
118 {
119 	int i;
120 
121 	if (masklen_valid(af, l) != 0 || n == NULL)
122 		return -1;
123 
124 	memset(n, '\0', sizeof(*n));
125 	switch (af) {
126 	case AF_INET:
127 		n->af = AF_INET;
128 		if (l == 0)
129 			return 0;
130 		n->v4.s_addr = htonl((0xffffffff << (32 - l)) & 0xffffffff);
131 		return 0;
132 	case AF_INET6:
133 		n->af = AF_INET6;
134 		for (i = 0; i < 4 && l >= 32; i++, l -= 32)
135 			n->addr32[i] = 0xffffffffU;
136 		if (i < 4 && l != 0)
137 			n->addr32[i] = htonl((0xffffffff << (32 - l)) &
138 			    0xffffffff);
139 		return 0;
140 	default:
141 		return -1;
142 	}
143 }
144 
145 /*
146  * Perform logical AND of addresses 'a' and 'b', storing result in 'dst'.
147  * Returns 0 on success, -1 on failure.
148  */
149 static int
addr_and(struct xaddr * dst,const struct xaddr * a,const struct xaddr * b)150 addr_and(struct xaddr *dst, const struct xaddr *a, const struct xaddr *b)
151 {
152 	int i;
153 
154 	if (dst == NULL || a == NULL || b == NULL || a->af != b->af)
155 		return -1;
156 
157 	memcpy(dst, a, sizeof(*dst));
158 	switch (a->af) {
159 	case AF_INET:
160 		dst->v4.s_addr &= b->v4.s_addr;
161 		return 0;
162 	case AF_INET6:
163 		dst->scope_id = a->scope_id;
164 		for (i = 0; i < 4; i++)
165 			dst->addr32[i] &= b->addr32[i];
166 		return 0;
167 	default:
168 		return -1;
169 	}
170 }
171 
172 /*
173  * Compare addresses 'a' and 'b'
174  * Return 0 if addresses are identical, -1 if (a < b) or 1 if (a > b)
175  */
176 static int
addr_cmp(const struct xaddr * a,const struct xaddr * b)177 addr_cmp(const struct xaddr *a, const struct xaddr *b)
178 {
179 	int i;
180 
181 	if (a->af != b->af)
182 		return a->af == AF_INET6 ? 1 : -1;
183 
184 	switch (a->af) {
185 	case AF_INET:
186 		if (a->v4.s_addr == b->v4.s_addr)
187 			return 0;
188 		return ntohl(a->v4.s_addr) > ntohl(b->v4.s_addr) ? 1 : -1;
189 	case AF_INET6:
190 		for (i = 0; i < 16; i++)
191 			if (a->addr8[i] - b->addr8[i] != 0)
192 				return a->addr8[i] > b->addr8[i] ? 1 : -1;
193 		if (a->scope_id == b->scope_id)
194 			return 0;
195 		return a->scope_id > b->scope_id ? 1 : -1;
196 	default:
197 		return -1;
198 	}
199 }
200 
201 /*
202  * Parse string address 'p' into 'n'
203  * Returns 0 on success, -1 on failure.
204  */
205 static int
addr_pton(const char * p,struct xaddr * n)206 addr_pton(const char *p, struct xaddr *n)
207 {
208 	struct addrinfo hints, *ai = NULL;
209 	int ret = -1;
210 
211 	memset(&hints, '\0', sizeof(hints));
212 	hints.ai_flags = AI_NUMERICHOST;
213 
214 	if (p == NULL || getaddrinfo(p, NULL, &hints, &ai) != 0)
215 		goto out;
216 	if (ai == NULL || ai->ai_addr == NULL)
217 		goto out;
218 	if (n != NULL && addr_sa_to_xaddr(ai->ai_addr, ai->ai_addrlen, n) == -1)
219 		goto out;
220 	/* success */
221 	ret = 0;
222  out:
223 	if (ai != NULL)
224 		freeaddrinfo(ai);
225 	return ret;
226 }
227 
228 /*
229  * Perform bitwise negation of address
230  * Returns 0 on success, -1 on failure.
231  */
232 static int
addr_invert(struct xaddr * n)233 addr_invert(struct xaddr *n)
234 {
235 	int i;
236 
237 	if (n == NULL)
238 		return (-1);
239 
240 	switch (n->af) {
241 	case AF_INET:
242 		n->v4.s_addr = ~n->v4.s_addr;
243 		return (0);
244 	case AF_INET6:
245 		for (i = 0; i < 4; i++)
246 			n->addr32[i] = ~n->addr32[i];
247 		return (0);
248 	default:
249 		return (-1);
250 	}
251 }
252 
253 /*
254  * Calculate a netmask of length 'l' for address family 'af' and
255  * store it in 'n'.
256  * Returns 0 on success, -1 on failure.
257  */
258 static int
addr_hostmask(int af,u_int l,struct xaddr * n)259 addr_hostmask(int af, u_int l, struct xaddr *n)
260 {
261 	if (addr_netmask(af, l, n) == -1 || addr_invert(n) == -1)
262 		return (-1);
263 	return (0);
264 }
265 
266 /*
267  * Test whether address 'a' is all zeros (i.e. 0.0.0.0 or ::)
268  * Returns 0 on if address is all-zeros, -1 if not all zeros or on failure.
269  */
270 static int
addr_is_all0s(const struct xaddr * a)271 addr_is_all0s(const struct xaddr *a)
272 {
273 	int i;
274 
275 	switch (a->af) {
276 	case AF_INET:
277 		return (a->v4.s_addr == 0 ? 0 : -1);
278 	case AF_INET6:;
279 		for (i = 0; i < 4; i++)
280 			if (a->addr32[i] != 0)
281 				return (-1);
282 		return (0);
283 	default:
284 		return (-1);
285 	}
286 }
287 
288 /*
289  * Test whether host portion of address 'a', as determined by 'masklen'
290  * is all zeros.
291  * Returns 0 on if host portion of address is all-zeros,
292  * -1 if not all zeros or on failure.
293  */
294 static int
addr_host_is_all0s(const struct xaddr * a,u_int masklen)295 addr_host_is_all0s(const struct xaddr *a, u_int masklen)
296 {
297 	struct xaddr tmp_addr, tmp_mask, tmp_result;
298 
299 	memcpy(&tmp_addr, a, sizeof(tmp_addr));
300 	if (addr_hostmask(a->af, masklen, &tmp_mask) == -1)
301 		return (-1);
302 	if (addr_and(&tmp_result, &tmp_addr, &tmp_mask) == -1)
303 		return (-1);
304 	return (addr_is_all0s(&tmp_result));
305 }
306 
307 /*
308  * Parse a CIDR address (x.x.x.x/y or xxxx:yyyy::/z).
309  * Return -1 on parse error, -2 on inconsistency or 0 on success.
310  */
311 static int
addr_pton_cidr(const char * p,struct xaddr * n,u_int * l)312 addr_pton_cidr(const char *p, struct xaddr *n, u_int *l)
313 {
314 	struct xaddr tmp;
315 	long unsigned int masklen = 999;
316 	char addrbuf[64], *mp, *cp;
317 
318 	/* Don't modify argument */
319 	if (p == NULL || strlcpy(addrbuf, p, sizeof(addrbuf)) >= sizeof(addrbuf))
320 		return -1;
321 
322 	if ((mp = strchr(addrbuf, '/')) != NULL) {
323 		*mp = '\0';
324 		mp++;
325 		masklen = strtoul(mp, &cp, 10);
326 		if (*mp == '\0' || *cp != '\0' || masklen > 128)
327 			return -1;
328 	}
329 
330 	if (addr_pton(addrbuf, &tmp) == -1)
331 		return -1;
332 
333 	if (mp == NULL)
334 		masklen = addr_unicast_masklen(tmp.af);
335 	if (masklen_valid(tmp.af, masklen) == -1)
336 		return -2;
337 	if (addr_host_is_all0s(&tmp, masklen) != 0)
338 		return -2;
339 
340 	if (n != NULL)
341 		memcpy(n, &tmp, sizeof(*n));
342 	if (l != NULL)
343 		*l = masklen;
344 
345 	return 0;
346 }
347 
348 static int
addr_netmatch(const struct xaddr * host,const struct xaddr * net,u_int masklen)349 addr_netmatch(const struct xaddr *host, const struct xaddr *net, u_int masklen)
350 {
351 	struct xaddr tmp_mask, tmp_result;
352 
353 	if (host->af != net->af)
354 		return -1;
355 
356 	if (addr_netmask(host->af, masklen, &tmp_mask) == -1)
357 		return -1;
358 	if (addr_and(&tmp_result, host, &tmp_mask) == -1)
359 		return -1;
360 	return addr_cmp(&tmp_result, net);
361 }
362 
363 /*
364  * Match "addr" against list pattern list "_list", which may contain a
365  * mix of CIDR addresses and old-school wildcards.
366  *
367  * If addr is NULL, then no matching is performed, but _list is parsed
368  * and checked for well-formedness.
369  *
370  * Returns 1 on match found (never returned when addr == NULL).
371  * Returns 0 on if no match found, or no errors found when addr == NULL.
372  * Returns -1 on negated match found (never returned when addr == NULL).
373  * Returns -2 on invalid list entry.
374  */
375 int
addr_match_list(const char * addr,const char * _list)376 addr_match_list(const char *addr, const char *_list)
377 {
378 	char *list, *cp, *o;
379 	struct xaddr try_addr, match_addr;
380 	u_int masklen, neg;
381 	int ret = 0, r;
382 
383 	if (addr != NULL && addr_pton(addr, &try_addr) != 0) {
384 		debug2("%s: couldn't parse address %.100s", __func__, addr);
385 		return 0;
386 	}
387 	if ((o = list = strdup(_list)) == NULL)
388 		return -1;
389 	while ((cp = strsep(&list, ",")) != NULL) {
390 		neg = *cp == '!';
391 		if (neg)
392 			cp++;
393 		if (*cp == '\0') {
394 			ret = -2;
395 			break;
396 		}
397 		/* Prefer CIDR address matching */
398 		r = addr_pton_cidr(cp, &match_addr, &masklen);
399 		if (r == -2) {
400 			debug2("%s: inconsistent mask length for "
401 			    "match network \"%.100s\"", __func__, cp);
402 			ret = -2;
403 			break;
404 		} else if (r == 0) {
405 			if (addr != NULL && addr_netmatch(&try_addr,
406                            &match_addr, masklen) == 0) {
407  foundit:
408 				if (neg) {
409 					ret = -1;
410 					break;
411 				}
412 				ret = 1;
413 			}
414 			continue;
415 		} else {
416 			/* If CIDR parse failed, try wildcard string match */
417 			if (addr != NULL && match_pattern(addr, cp) == 1)
418 				goto foundit;
419 		}
420 	}
421 	free(o);
422 
423 	return ret;
424 }
425 
426 /*
427  * Match "addr" against list CIDR list "_list". Lexical wildcards and
428  * negation are not supported. If "addr" == NULL, will verify structure
429  * of "_list".
430  *
431  * Returns 1 on match found (never returned when addr == NULL).
432  * Returns 0 on if no match found, or no errors found when addr == NULL.
433  * Returns -1 on error
434  */
435 int
addr_match_cidr_list(const char * addr,const char * _list)436 addr_match_cidr_list(const char *addr, const char *_list)
437 {
438 	char *list, *cp, *o;
439 	struct xaddr try_addr, match_addr;
440 	u_int masklen;
441 	int ret = 0, r;
442 
443 	if (addr != NULL && addr_pton(addr, &try_addr) != 0) {
444 		debug2("%s: couldn't parse address %.100s", __func__, addr);
445 		return 0;
446 	}
447 	if ((o = list = strdup(_list)) == NULL)
448 		return -1;
449 	while ((cp = strsep(&list, ",")) != NULL) {
450 		if (*cp == '\0') {
451 			error("%s: empty entry in list \"%.100s\"",
452 			    __func__, o);
453 			ret = -1;
454 			break;
455 		}
456 
457 		/*
458 		 * NB. This function is called in pre-auth with untrusted data,
459 		 * so be extra paranoid about junk reaching getaddrino (via
460 		 * addr_pton_cidr).
461 		 */
462 
463 		/* Stop junk from reaching getaddrinfo. +3 is for masklen */
464 		if (strlen(cp) > INET6_ADDRSTRLEN + 3) {
465 			error("%s: list entry \"%.100s\" too long",
466 			    __func__, cp);
467 			ret = -1;
468 			break;
469 		}
470 #define VALID_CIDR_CHARS "0123456789abcdefABCDEF.:/"
471 		if (strspn(cp, VALID_CIDR_CHARS) != strlen(cp)) {
472 			error("%s: list entry \"%.100s\" contains invalid "
473 			    "characters", __func__, cp);
474 			ret = -1;
475 		}
476 
477 		/* Prefer CIDR address matching */
478 		r = addr_pton_cidr(cp, &match_addr, &masklen);
479 		if (r == -1) {
480 			error("Invalid network entry \"%.100s\"", cp);
481 			ret = -1;
482 			break;
483 		} else if (r == -2) {
484 			error("Inconsistent mask length for "
485 			    "network \"%.100s\"", cp);
486 			ret = -1;
487 			break;
488 		} else if (r == 0 && addr != NULL) {
489 			if (addr_netmatch(&try_addr, &match_addr,
490 			    masklen) == 0)
491 				ret = 1;
492 			continue;
493 		}
494 	}
495 	free(o);
496 
497 	return ret;
498 }
499