addrmatch.c revision 1.11 
1/*	$OpenBSD: addrmatch.c,v 1.11 2016/08/23 03:24:10 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 <sys/types.h>
20#include <sys/socket.h>
21#include <netinet/in.h>
22#include <arpa/inet.h>
23
24#include <netdb.h>
25#include <string.h>
26#include <stdlib.h>
27#include <stdio.h>
28#include <stdarg.h>
29
30#include "match.h"
31#include "log.h"
32
33struct xaddr {
34	sa_family_t	af;
35	union {
36		struct in_addr		v4;
37		struct in6_addr		v6;
38		u_int8_t		addr8[16];
39		u_int32_t		addr32[4];
40	} xa;		    /* 128-bit address */
41	u_int32_t	scope_id;	/* iface scope id for v6 */
42#define v4	xa.v4
43#define v6	xa.v6
44#define addr8	xa.addr8
45#define addr32	xa.addr32
46};
47
48static int
49addr_unicast_masklen(int af)
50{
51	switch (af) {
52	case AF_INET:
53		return 32;
54	case AF_INET6:
55		return 128;
56	default:
57		return -1;
58	}
59}
60
61static inline int
62masklen_valid(int af, u_int masklen)
63{
64	switch (af) {
65	case AF_INET:
66		return masklen <= 32 ? 0 : -1;
67	case AF_INET6:
68		return masklen <= 128 ? 0 : -1;
69	default:
70		return -1;
71	}
72}
73
74/*
75 * Convert struct sockaddr to struct xaddr
76 * Returns 0 on success, -1 on failure.
77 */
78static int
79addr_sa_to_xaddr(struct sockaddr *sa, socklen_t slen, struct xaddr *xa)
80{
81	struct sockaddr_in *in4 = (struct sockaddr_in *)sa;
82	struct sockaddr_in6 *in6 = (struct sockaddr_in6 *)sa;
83
84	memset(xa, '\0', sizeof(*xa));
85
86	switch (sa->sa_family) {
87	case AF_INET:
88		if (slen < (socklen_t)sizeof(*in4))
89			return -1;
90		xa->af = AF_INET;
91		memcpy(&xa->v4, &in4->sin_addr, sizeof(xa->v4));
92		break;
93	case AF_INET6:
94		if (slen < (socklen_t)sizeof(*in6))
95			return -1;
96		xa->af = AF_INET6;
97		memcpy(&xa->v6, &in6->sin6_addr, sizeof(xa->v6));
98		xa->scope_id = in6->sin6_scope_id;
99		break;
100	default:
101		return -1;
102	}
103
104	return 0;
105}
106
107/*
108 * Calculate a netmask of length 'l' for address family 'af' and
109 * store it in 'n'.
110 * Returns 0 on success, -1 on failure.
111 */
112static int
113addr_netmask(int af, u_int l, struct xaddr *n)
114{
115	int i;
116
117	if (masklen_valid(af, l) != 0 || n == NULL)
118		return -1;
119
120	memset(n, '\0', sizeof(*n));
121	switch (af) {
122	case AF_INET:
123		n->af = AF_INET;
124		if (l == 0)
125			return 0;
126		n->v4.s_addr = htonl((0xffffffff << (32 - l)) & 0xffffffff);
127		return 0;
128	case AF_INET6:
129		n->af = AF_INET6;
130		for (i = 0; i < 4 && l >= 32; i++, l -= 32)
131			n->addr32[i] = 0xffffffffU;
132		if (i < 4 && l != 0)
133			n->addr32[i] = htonl((0xffffffff << (32 - l)) &
134			    0xffffffff);
135		return 0;
136	default:
137		return -1;
138	}
139}
140
141/*
142 * Perform logical AND of addresses 'a' and 'b', storing result in 'dst'.
143 * Returns 0 on success, -1 on failure.
144 */
145static int
146addr_and(struct xaddr *dst, const struct xaddr *a, const struct xaddr *b)
147{
148	int i;
149
150	if (dst == NULL || a == NULL || b == NULL || a->af != b->af)
151		return -1;
152
153	memcpy(dst, a, sizeof(*dst));
154	switch (a->af) {
155	case AF_INET:
156		dst->v4.s_addr &= b->v4.s_addr;
157		return 0;
158	case AF_INET6:
159		dst->scope_id = a->scope_id;
160		for (i = 0; i < 4; i++)
161			dst->addr32[i] &= b->addr32[i];
162		return 0;
163	default:
164		return -1;
165	}
166}
167
168/*
169 * Compare addresses 'a' and 'b'
170 * Return 0 if addresses are identical, -1 if (a < b) or 1 if (a > b)
171 */
172static int
173addr_cmp(const struct xaddr *a, const struct xaddr *b)
174{
175	int i;
176
177	if (a->af != b->af)
178		return a->af == AF_INET6 ? 1 : -1;
179
180	switch (a->af) {
181	case AF_INET:
182		if (a->v4.s_addr == b->v4.s_addr)
183			return 0;
184		return ntohl(a->v4.s_addr) > ntohl(b->v4.s_addr) ? 1 : -1;
185	case AF_INET6:
186		for (i = 0; i < 16; i++)
187			if (a->addr8[i] - b->addr8[i] != 0)
188				return a->addr8[i] > b->addr8[i] ? 1 : -1;
189		if (a->scope_id == b->scope_id)
190			return 0;
191		return a->scope_id > b->scope_id ? 1 : -1;
192	default:
193		return -1;
194	}
195}
196
197/*
198 * Parse string address 'p' into 'n'
199 * Returns 0 on success, -1 on failure.
200 */
201static int
202addr_pton(const char *p, struct xaddr *n)
203{
204	struct addrinfo hints, *ai;
205
206	memset(&hints, '\0', sizeof(hints));
207	hints.ai_flags = AI_NUMERICHOST;
208
209	if (p == NULL || getaddrinfo(p, NULL, &hints, &ai) != 0)
210		return -1;
211
212	if (ai == NULL || ai->ai_addr == NULL)
213		return -1;
214
215	if (n != NULL &&
216	    addr_sa_to_xaddr(ai->ai_addr, ai->ai_addrlen, n) == -1) {
217		freeaddrinfo(ai);
218		return -1;
219	}
220
221	freeaddrinfo(ai);
222	return 0;
223}
224
225/*
226 * Perform bitwise negation of address
227 * Returns 0 on success, -1 on failure.
228 */
229static int
230addr_invert(struct xaddr *n)
231{
232	int i;
233
234	if (n == NULL)
235		return (-1);
236
237	switch (n->af) {
238	case AF_INET:
239		n->v4.s_addr = ~n->v4.s_addr;
240		return (0);
241	case AF_INET6:
242		for (i = 0; i < 4; i++)
243			n->addr32[i] = ~n->addr32[i];
244		return (0);
245	default:
246		return (-1);
247	}
248}
249
250/*
251 * Calculate a netmask of length 'l' for address family 'af' and
252 * store it in 'n'.
253 * Returns 0 on success, -1 on failure.
254 */
255static int
256addr_hostmask(int af, u_int l, struct xaddr *n)
257{
258	if (addr_netmask(af, l, n) == -1 || addr_invert(n) == -1)
259		return (-1);
260	return (0);
261}
262
263/*
264 * Test whether address 'a' is all zeros (i.e. 0.0.0.0 or ::)
265 * Returns 0 on if address is all-zeros, -1 if not all zeros or on failure.
266 */
267static int
268addr_is_all0s(const struct xaddr *a)
269{
270	int i;
271
272	switch (a->af) {
273	case AF_INET:
274		return (a->v4.s_addr == 0 ? 0 : -1);
275	case AF_INET6:;
276		for (i = 0; i < 4; i++)
277			if (a->addr32[i] != 0)
278				return (-1);
279		return (0);
280	default:
281		return (-1);
282	}
283}
284
285/*
286 * Test whether host portion of address 'a', as determined by 'masklen'
287 * is all zeros.
288 * Returns 0 on if host portion of address is all-zeros,
289 * -1 if not all zeros or on failure.
290 */
291static int
292addr_host_is_all0s(const struct xaddr *a, u_int masklen)
293{
294	struct xaddr tmp_addr, tmp_mask, tmp_result;
295
296	memcpy(&tmp_addr, a, sizeof(tmp_addr));
297	if (addr_hostmask(a->af, masklen, &tmp_mask) == -1)
298		return (-1);
299	if (addr_and(&tmp_result, &tmp_addr, &tmp_mask) == -1)
300		return (-1);
301	return (addr_is_all0s(&tmp_result));
302}
303
304/*
305 * Parse a CIDR address (x.x.x.x/y or xxxx:yyyy::/z).
306 * Return -1 on parse error, -2 on inconsistency or 0 on success.
307 */
308static int
309addr_pton_cidr(const char *p, struct xaddr *n, u_int *l)
310{
311	struct xaddr tmp;
312	long unsigned int masklen = 999;
313	char addrbuf[64], *mp, *cp;
314
315	/* Don't modify argument */
316	if (p == NULL || strlcpy(addrbuf, p, sizeof(addrbuf)) >= sizeof(addrbuf))
317		return -1;
318
319	if ((mp = strchr(addrbuf, '/')) != NULL) {
320		*mp = '\0';
321		mp++;
322		masklen = strtoul(mp, &cp, 10);
323		if (*mp == '\0' || *cp != '\0' || masklen > 128)
324			return -1;
325	}
326
327	if (addr_pton(addrbuf, &tmp) == -1)
328		return -1;
329
330	if (mp == NULL)
331		masklen = addr_unicast_masklen(tmp.af);
332	if (masklen_valid(tmp.af, masklen) == -1)
333		return -2;
334	if (addr_host_is_all0s(&tmp, masklen) != 0)
335		return -2;
336
337	if (n != NULL)
338		memcpy(n, &tmp, sizeof(*n));
339	if (l != NULL)
340		*l = masklen;
341
342	return 0;
343}
344
345static int
346addr_netmatch(const struct xaddr *host, const struct xaddr *net, u_int masklen)
347{
348	struct xaddr tmp_mask, tmp_result;
349
350	if (host->af != net->af)
351		return -1;
352
353	if (addr_netmask(host->af, masklen, &tmp_mask) == -1)
354		return -1;
355	if (addr_and(&tmp_result, host, &tmp_mask) == -1)
356		return -1;
357	return addr_cmp(&tmp_result, net);
358}
359
360/*
361 * Match "addr" against list pattern list "_list", which may contain a
362 * mix of CIDR addresses and old-school wildcards.
363 *
364 * If addr is NULL, then no matching is performed, but _list is parsed
365 * and checked for well-formedness.
366 *
367 * Returns 1 on match found (never returned when addr == NULL).
368 * Returns 0 on if no match found, or no errors found when addr == NULL.
369 * Returns -1 on negated match found (never returned when addr == NULL).
370 * Returns -2 on invalid list entry.
371 */
372int
373addr_match_list(const char *addr, const char *_list)
374{
375	char *list, *cp, *o;
376	struct xaddr try_addr, match_addr;
377	u_int masklen, neg;
378	int ret = 0, r;
379
380	if (addr != NULL && addr_pton(addr, &try_addr) != 0) {
381		debug2("%s: couldn't parse address %.100s", __func__, addr);
382		return 0;
383	}
384	if ((o = list = strdup(_list)) == NULL)
385		return -1;
386	while ((cp = strsep(&list, ",")) != NULL) {
387		neg = *cp == '!';
388		if (neg)
389			cp++;
390		if (*cp == '\0') {
391			ret = -2;
392			break;
393		}
394		/* Prefer CIDR address matching */
395		r = addr_pton_cidr(cp, &match_addr, &masklen);
396		if (r == -2) {
397			error("Inconsistent mask length for "
398			    "network \"%.100s\"", cp);
399			ret = -2;
400			break;
401		} else if (r == 0) {
402			if (addr != NULL && addr_netmatch(&try_addr,
403                           &match_addr, masklen) == 0) {
404 foundit:
405				if (neg) {
406					ret = -1;
407					break;
408				}
409				ret = 1;
410			} else if (neg)
411				ret = 1;
412			continue;
413		} else {
414			/* If CIDR parse failed, try wildcard string match */
415			if (addr != NULL && match_pattern(addr, cp) == 1)
416				goto foundit;
417		}
418	}
419	free(o);
420
421	return ret;
422}
423
424/*
425 * Match "addr" against list CIDR list "_list". Lexical wildcards and
426 * negation are not supported. If "addr" == NULL, will verify structure
427 * of "_list".
428 *
429 * Returns 1 on match found (never returned when addr == NULL).
430 * Returns 0 on if no match found, or no errors found when addr == NULL.
431 * Returns -1 on error
432 */
433int
434addr_match_cidr_list(const char *addr, const char *_list)
435{
436	char *list, *cp, *o;
437	struct xaddr try_addr, match_addr;
438	u_int masklen;
439	int ret = 0, r;
440
441	if (addr != NULL && addr_pton(addr, &try_addr) != 0) {
442		debug2("%s: couldn't parse address %.100s", __func__, addr);
443		return 0;
444	}
445	if ((o = list = strdup(_list)) == NULL)
446		return -1;
447	while ((cp = strsep(&list, ",")) != NULL) {
448		if (*cp == '\0') {
449			error("%s: empty entry in list \"%.100s\"",
450			    __func__, o);
451			ret = -1;
452			break;
453		}
454
455		/*
456		 * NB. This function is called in pre-auth with untrusted data,
457		 * so be extra paranoid about junk reaching getaddrino (via
458		 * addr_pton_cidr).
459		 */
460
461		/* Stop junk from reaching getaddrinfo. +3 is for masklen */
462		if (strlen(cp) > INET6_ADDRSTRLEN + 3) {
463			error("%s: list entry \"%.100s\" too long",
464			    __func__, cp);
465			ret = -1;
466			break;
467		}
468#define VALID_CIDR_CHARS "0123456789abcdefABCDEF.:/"
469		if (strspn(cp, VALID_CIDR_CHARS) != strlen(cp)) {
470			error("%s: list entry \"%.100s\" contains invalid "
471			    "characters", __func__, cp);
472			ret = -1;
473		}
474
475		/* Prefer CIDR address matching */
476		r = addr_pton_cidr(cp, &match_addr, &masklen);
477		if (r == -1) {
478			error("Invalid network entry \"%.100s\"", cp);
479			ret = -1;
480			break;
481		} else if (r == -2) {
482			error("Inconsistent mask length for "
483			    "network \"%.100s\"", cp);
484			ret = -1;
485			break;
486		} else if (r == 0 && addr != NULL) {
487			if (addr_netmatch(&try_addr, &match_addr,
488			    masklen) == 0)
489				ret = 1;
490			continue;
491		}
492	}
493	free(o);
494
495	return ret;
496}
497