addrmatch.c revision 323134 
1/*	$OpenBSD: addrmatch.c,v 1.13 2016/09/21 16:55:42 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
35struct 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
50static int
51addr_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
63static inline int
64masklen_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 */
80static int
81addr_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 */
116static int
117addr_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 */
149static int
150addr_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 */
176static int
177addr_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 */
205static int
206addr_pton(const char *p, struct xaddr *n)
207{
208	struct addrinfo hints, *ai;
209
210	memset(&hints, '\0', sizeof(hints));
211	hints.ai_flags = AI_NUMERICHOST;
212
213	if (p == NULL || getaddrinfo(p, NULL, &hints, &ai) != 0)
214		return -1;
215
216	if (ai == NULL || ai->ai_addr == NULL)
217		return -1;
218
219	if (n != NULL &&
220	    addr_sa_to_xaddr(ai->ai_addr, ai->ai_addrlen, n) == -1) {
221		freeaddrinfo(ai);
222		return -1;
223	}
224
225	freeaddrinfo(ai);
226	return 0;
227}
228
229/*
230 * Perform bitwise negation of address
231 * Returns 0 on success, -1 on failure.
232 */
233static int
234addr_invert(struct xaddr *n)
235{
236	int i;
237
238	if (n == NULL)
239		return (-1);
240
241	switch (n->af) {
242	case AF_INET:
243		n->v4.s_addr = ~n->v4.s_addr;
244		return (0);
245	case AF_INET6:
246		for (i = 0; i < 4; i++)
247			n->addr32[i] = ~n->addr32[i];
248		return (0);
249	default:
250		return (-1);
251	}
252}
253
254/*
255 * Calculate a netmask of length 'l' for address family 'af' and
256 * store it in 'n'.
257 * Returns 0 on success, -1 on failure.
258 */
259static int
260addr_hostmask(int af, u_int l, struct xaddr *n)
261{
262	if (addr_netmask(af, l, n) == -1 || addr_invert(n) == -1)
263		return (-1);
264	return (0);
265}
266
267/*
268 * Test whether address 'a' is all zeros (i.e. 0.0.0.0 or ::)
269 * Returns 0 on if address is all-zeros, -1 if not all zeros or on failure.
270 */
271static int
272addr_is_all0s(const struct xaddr *a)
273{
274	int i;
275
276	switch (a->af) {
277	case AF_INET:
278		return (a->v4.s_addr == 0 ? 0 : -1);
279	case AF_INET6:;
280		for (i = 0; i < 4; i++)
281			if (a->addr32[i] != 0)
282				return (-1);
283		return (0);
284	default:
285		return (-1);
286	}
287}
288
289/*
290 * Test whether host portion of address 'a', as determined by 'masklen'
291 * is all zeros.
292 * Returns 0 on if host portion of address is all-zeros,
293 * -1 if not all zeros or on failure.
294 */
295static int
296addr_host_is_all0s(const struct xaddr *a, u_int masklen)
297{
298	struct xaddr tmp_addr, tmp_mask, tmp_result;
299
300	memcpy(&tmp_addr, a, sizeof(tmp_addr));
301	if (addr_hostmask(a->af, masklen, &tmp_mask) == -1)
302		return (-1);
303	if (addr_and(&tmp_result, &tmp_addr, &tmp_mask) == -1)
304		return (-1);
305	return (addr_is_all0s(&tmp_result));
306}
307
308/*
309 * Parse a CIDR address (x.x.x.x/y or xxxx:yyyy::/z).
310 * Return -1 on parse error, -2 on inconsistency or 0 on success.
311 */
312static int
313addr_pton_cidr(const char *p, struct xaddr *n, u_int *l)
314{
315	struct xaddr tmp;
316	long unsigned int masklen = 999;
317	char addrbuf[64], *mp, *cp;
318
319	/* Don't modify argument */
320	if (p == NULL || strlcpy(addrbuf, p, sizeof(addrbuf)) >= sizeof(addrbuf))
321		return -1;
322
323	if ((mp = strchr(addrbuf, '/')) != NULL) {
324		*mp = '\0';
325		mp++;
326		masklen = strtoul(mp, &cp, 10);
327		if (*mp == '\0' || *cp != '\0' || masklen > 128)
328			return -1;
329	}
330
331	if (addr_pton(addrbuf, &tmp) == -1)
332		return -1;
333
334	if (mp == NULL)
335		masklen = addr_unicast_masklen(tmp.af);
336	if (masklen_valid(tmp.af, masklen) == -1)
337		return -2;
338	if (addr_host_is_all0s(&tmp, masklen) != 0)
339		return -2;
340
341	if (n != NULL)
342		memcpy(n, &tmp, sizeof(*n));
343	if (l != NULL)
344		*l = masklen;
345
346	return 0;
347}
348
349static int
350addr_netmatch(const struct xaddr *host, const struct xaddr *net, u_int masklen)
351{
352	struct xaddr tmp_mask, tmp_result;
353
354	if (host->af != net->af)
355		return -1;
356
357	if (addr_netmask(host->af, masklen, &tmp_mask) == -1)
358		return -1;
359	if (addr_and(&tmp_result, host, &tmp_mask) == -1)
360		return -1;
361	return addr_cmp(&tmp_result, net);
362}
363
364/*
365 * Match "addr" against list pattern list "_list", which may contain a
366 * mix of CIDR addresses and old-school wildcards.
367 *
368 * If addr is NULL, then no matching is performed, but _list is parsed
369 * and checked for well-formedness.
370 *
371 * Returns 1 on match found (never returned when addr == NULL).
372 * Returns 0 on if no match found, or no errors found when addr == NULL.
373 * Returns -1 on negated match found (never returned when addr == NULL).
374 * Returns -2 on invalid list entry.
375 */
376int
377addr_match_list(const char *addr, const char *_list)
378{
379	char *list, *cp, *o;
380	struct xaddr try_addr, match_addr;
381	u_int masklen, neg;
382	int ret = 0, r;
383
384	if (addr != NULL && addr_pton(addr, &try_addr) != 0) {
385		debug2("%s: couldn't parse address %.100s", __func__, addr);
386		return 0;
387	}
388	if ((o = list = strdup(_list)) == NULL)
389		return -1;
390	while ((cp = strsep(&list, ",")) != NULL) {
391		neg = *cp == '!';
392		if (neg)
393			cp++;
394		if (*cp == '\0') {
395			ret = -2;
396			break;
397		}
398		/* Prefer CIDR address matching */
399		r = addr_pton_cidr(cp, &match_addr, &masklen);
400		if (r == -2) {
401			debug2("%s: inconsistent mask length for "
402			    "match network \"%.100s\"", __func__, cp);
403			ret = -2;
404			break;
405		} else if (r == 0) {
406			if (addr != NULL && addr_netmatch(&try_addr,
407                           &match_addr, masklen) == 0) {
408 foundit:
409				if (neg) {
410					ret = -1;
411					break;
412				}
413				ret = 1;
414			}
415			continue;
416		} else {
417			/* If CIDR parse failed, try wildcard string match */
418			if (addr != NULL && match_pattern(addr, cp) == 1)
419				goto foundit;
420		}
421	}
422	free(o);
423
424	return ret;
425}
426
427/*
428 * Match "addr" against list CIDR list "_list". Lexical wildcards and
429 * negation are not supported. If "addr" == NULL, will verify structure
430 * of "_list".
431 *
432 * Returns 1 on match found (never returned when addr == NULL).
433 * Returns 0 on if no match found, or no errors found when addr == NULL.
434 * Returns -1 on error
435 */
436int
437addr_match_cidr_list(const char *addr, const char *_list)
438{
439	char *list, *cp, *o;
440	struct xaddr try_addr, match_addr;
441	u_int masklen;
442	int ret = 0, r;
443
444	if (addr != NULL && addr_pton(addr, &try_addr) != 0) {
445		debug2("%s: couldn't parse address %.100s", __func__, addr);
446		return 0;
447	}
448	if ((o = list = strdup(_list)) == NULL)
449		return -1;
450	while ((cp = strsep(&list, ",")) != NULL) {
451		if (*cp == '\0') {
452			error("%s: empty entry in list \"%.100s\"",
453			    __func__, o);
454			ret = -1;
455			break;
456		}
457
458		/*
459		 * NB. This function is called in pre-auth with untrusted data,
460		 * so be extra paranoid about junk reaching getaddrino (via
461		 * addr_pton_cidr).
462		 */
463
464		/* Stop junk from reaching getaddrinfo. +3 is for masklen */
465		if (strlen(cp) > INET6_ADDRSTRLEN + 3) {
466			error("%s: list entry \"%.100s\" too long",
467			    __func__, cp);
468			ret = -1;
469			break;
470		}
471#define VALID_CIDR_CHARS "0123456789abcdefABCDEF.:/"
472		if (strspn(cp, VALID_CIDR_CHARS) != strlen(cp)) {
473			error("%s: list entry \"%.100s\" contains invalid "
474			    "characters", __func__, cp);
475			ret = -1;
476		}
477
478		/* Prefer CIDR address matching */
479		r = addr_pton_cidr(cp, &match_addr, &masklen);
480		if (r == -1) {
481			error("Invalid network entry \"%.100s\"", cp);
482			ret = -1;
483			break;
484		} else if (r == -2) {
485			error("Inconsistent mask length for "
486			    "network \"%.100s\"", cp);
487			ret = -1;
488			break;
489		} else if (r == 0 && addr != NULL) {
490			if (addr_netmatch(&try_addr, &match_addr,
491			    masklen) == 0)
492				ret = 1;
493			continue;
494		}
495	}
496	free(o);
497
498	return ret;
499}
500