addrmatch.c revision 1.6 
1/*	$OpenBSD: addrmatch.c,v 1.6 2012/06/21 00:16:07 dtucker 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#include "xmalloc.h"
33
34struct xaddr {
35	sa_family_t	af;
36	union {
37		struct in_addr		v4;
38		struct in6_addr		v6;
39		u_int8_t		addr8[16];
40		u_int32_t		addr32[4];
41	} xa;		    /* 128-bit address */
42	u_int32_t	scope_id;	/* iface scope id for v6 */
43#define v4	xa.v4
44#define v6	xa.v6
45#define addr8	xa.addr8
46#define addr32	xa.addr32
47};
48
49static int
50addr_unicast_masklen(int af)
51{
52	switch (af) {
53	case AF_INET:
54		return 32;
55	case AF_INET6:
56		return 128;
57	default:
58		return -1;
59	}
60}
61
62static inline int
63masklen_valid(int af, u_int masklen)
64{
65	switch (af) {
66	case AF_INET:
67		return masklen <= 32 ? 0 : -1;
68	case AF_INET6:
69		return masklen <= 128 ? 0 : -1;
70	default:
71		return -1;
72	}
73}
74
75/*
76 * Convert struct sockaddr to struct xaddr
77 * Returns 0 on success, -1 on failure.
78 */
79static int
80addr_sa_to_xaddr(struct sockaddr *sa, socklen_t slen, struct xaddr *xa)
81{
82	struct sockaddr_in *in4 = (struct sockaddr_in *)sa;
83	struct sockaddr_in6 *in6 = (struct sockaddr_in6 *)sa;
84
85	memset(xa, '\0', sizeof(*xa));
86
87	switch (sa->sa_family) {
88	case AF_INET:
89		if (slen < sizeof(*in4))
90			return -1;
91		xa->af = AF_INET;
92		memcpy(&xa->v4, &in4->sin_addr, sizeof(xa->v4));
93		break;
94	case AF_INET6:
95		if (slen < sizeof(*in6))
96			return -1;
97		xa->af = AF_INET6;
98		memcpy(&xa->v6, &in6->sin6_addr, sizeof(xa->v6));
99		xa->scope_id = in6->sin6_scope_id;
100		break;
101	default:
102		return -1;
103	}
104
105	return 0;
106}
107
108/*
109 * Calculate a netmask of length 'l' for address family 'af' and
110 * store it in 'n'.
111 * Returns 0 on success, -1 on failure.
112 */
113static int
114addr_netmask(int af, u_int l, struct xaddr *n)
115{
116	int i;
117
118	if (masklen_valid(af, l) != 0 || n == NULL)
119		return -1;
120
121	memset(n, '\0', sizeof(*n));
122	switch (af) {
123	case AF_INET:
124		n->af = AF_INET;
125		if (l == 0)
126			return 0;
127		n->v4.s_addr = htonl((0xffffffff << (32 - l)) & 0xffffffff);
128		return 0;
129	case AF_INET6:
130		n->af = AF_INET6;
131		for (i = 0; i < 4 && l >= 32; i++, l -= 32)
132			n->addr32[i] = 0xffffffffU;
133		if (i < 4 && l != 0)
134			n->addr32[i] = htonl((0xffffffff << (32 - l)) &
135			    0xffffffff);
136		return 0;
137	default:
138		return -1;
139	}
140}
141
142/*
143 * Perform logical AND of addresses 'a' and 'b', storing result in 'dst'.
144 * Returns 0 on success, -1 on failure.
145 */
146static int
147addr_and(struct xaddr *dst, const struct xaddr *a, const struct xaddr *b)
148{
149	int i;
150
151	if (dst == NULL || a == NULL || b == NULL || a->af != b->af)
152		return -1;
153
154	memcpy(dst, a, sizeof(*dst));
155	switch (a->af) {
156	case AF_INET:
157		dst->v4.s_addr &= b->v4.s_addr;
158		return 0;
159	case AF_INET6:
160		dst->scope_id = a->scope_id;
161		for (i = 0; i < 4; i++)
162			dst->addr32[i] &= b->addr32[i];
163		return 0;
164	default:
165		return -1;
166	}
167}
168
169/*
170 * Compare addresses 'a' and 'b'
171 * Return 0 if addresses are identical, -1 if (a < b) or 1 if (a > b)
172 */
173static int
174addr_cmp(const struct xaddr *a, const struct xaddr *b)
175{
176	int i;
177
178	if (a->af != b->af)
179		return a->af == AF_INET6 ? 1 : -1;
180
181	switch (a->af) {
182	case AF_INET:
183		if (a->v4.s_addr == b->v4.s_addr)
184			return 0;
185		return ntohl(a->v4.s_addr) > ntohl(b->v4.s_addr) ? 1 : -1;
186	case AF_INET6:
187		for (i = 0; i < 16; i++)
188			if (a->addr8[i] - b->addr8[i] != 0)
189				return a->addr8[i] > b->addr8[i] ? 1 : -1;
190		if (a->scope_id == b->scope_id)
191			return 0;
192		return a->scope_id > b->scope_id ? 1 : -1;
193	default:
194		return -1;
195	}
196}
197
198/*
199 * Parse string address 'p' into 'n'
200 * Returns 0 on success, -1 on failure.
201 */
202static int
203addr_pton(const char *p, struct xaddr *n)
204{
205	struct addrinfo hints, *ai;
206
207	memset(&hints, '\0', sizeof(hints));
208	hints.ai_flags = AI_NUMERICHOST;
209
210	if (p == NULL || getaddrinfo(p, NULL, &hints, &ai) != 0)
211		return -1;
212
213	if (ai == NULL || ai->ai_addr == NULL)
214		return -1;
215
216	if (n != NULL &&
217	    addr_sa_to_xaddr(ai->ai_addr, ai->ai_addrlen, n) == -1) {
218		freeaddrinfo(ai);
219		return -1;
220	}
221
222	freeaddrinfo(ai);
223	return 0;
224}
225
226/*
227 * Perform bitwise negation of address
228 * Returns 0 on success, -1 on failure.
229 */
230static int
231addr_invert(struct xaddr *n)
232{
233	int i;
234
235	if (n == NULL)
236		return (-1);
237
238	switch (n->af) {
239	case AF_INET:
240		n->v4.s_addr = ~n->v4.s_addr;
241		return (0);
242	case AF_INET6:
243		for (i = 0; i < 4; i++)
244			n->addr32[i] = ~n->addr32[i];
245		return (0);
246	default:
247		return (-1);
248	}
249}
250
251/*
252 * Calculate a netmask of length 'l' for address family 'af' and
253 * store it in 'n'.
254 * Returns 0 on success, -1 on failure.
255 */
256static int
257addr_hostmask(int af, u_int l, struct xaddr *n)
258{
259	if (addr_netmask(af, l, n) == -1 || addr_invert(n) == -1)
260		return (-1);
261	return (0);
262}
263
264/*
265 * Test whether address 'a' is all zeros (i.e. 0.0.0.0 or ::)
266 * Returns 0 on if address is all-zeros, -1 if not all zeros or on failure.
267 */
268static int
269addr_is_all0s(const struct xaddr *a)
270{
271	int i;
272
273	switch (a->af) {
274	case AF_INET:
275		return (a->v4.s_addr == 0 ? 0 : -1);
276	case AF_INET6:;
277		for (i = 0; i < 4; i++)
278			if (a->addr32[i] != 0)
279				return (-1);
280		return (0);
281	default:
282		return (-1);
283	}
284}
285
286/*
287 * Test whether host portion of address 'a', as determined by 'masklen'
288 * is all zeros.
289 * Returns 0 on if host portion of address is all-zeros,
290 * -1 if not all zeros or on failure.
291 */
292static int
293addr_host_is_all0s(const struct xaddr *a, u_int masklen)
294{
295	struct xaddr tmp_addr, tmp_mask, tmp_result;
296
297	memcpy(&tmp_addr, a, sizeof(tmp_addr));
298	if (addr_hostmask(a->af, masklen, &tmp_mask) == -1)
299		return (-1);
300	if (addr_and(&tmp_result, &tmp_addr, &tmp_mask) == -1)
301		return (-1);
302	return (addr_is_all0s(&tmp_result));
303}
304
305/*
306 * Parse a CIDR address (x.x.x.x/y or xxxx:yyyy::/z).
307 * Return -1 on parse error, -2 on inconsistency or 0 on success.
308 */
309static int
310addr_pton_cidr(const char *p, struct xaddr *n, u_int *l)
311{
312	struct xaddr tmp;
313	long unsigned int masklen = 999;
314	char addrbuf[64], *mp, *cp;
315
316	/* Don't modify argument */
317	if (p == NULL || strlcpy(addrbuf, p, sizeof(addrbuf)) >= sizeof(addrbuf))
318		return -1;
319
320	if ((mp = strchr(addrbuf, '/')) != NULL) {
321		*mp = '\0';
322		mp++;
323		masklen = strtoul(mp, &cp, 10);
324		if (*mp == '\0' || *cp != '\0' || masklen > 128)
325			return -1;
326	}
327
328	if (addr_pton(addrbuf, &tmp) == -1)
329		return -1;
330
331	if (mp == NULL)
332		masklen = addr_unicast_masklen(tmp.af);
333	if (masklen_valid(tmp.af, masklen) == -1)
334		return -2;
335	if (addr_host_is_all0s(&tmp, masklen) != 0)
336		return -2;
337
338	if (n != NULL)
339		memcpy(n, &tmp, sizeof(*n));
340	if (l != NULL)
341		*l = masklen;
342
343	return 0;
344}
345
346static int
347addr_netmatch(const struct xaddr *host, const struct xaddr *net, u_int masklen)
348{
349	struct xaddr tmp_mask, tmp_result;
350
351	if (host->af != net->af)
352		return -1;
353
354	if (addr_netmask(host->af, masklen, &tmp_mask) == -1)
355		return -1;
356	if (addr_and(&tmp_result, host, &tmp_mask) == -1)
357		return -1;
358	return addr_cmp(&tmp_result, net);
359}
360
361/*
362 * Match "addr" against list pattern list "_list", which may contain a
363 * mix of CIDR addresses and old-school wildcards.
364 *
365 * If addr is NULL, then no matching is performed, but _list is parsed
366 * and checked for well-formedness.
367 *
368 * Returns 1 on match found (never returned when addr == NULL).
369 * Returns 0 on if no match found, or no errors found when addr == NULL.
370 * Returns -1 on negated match found (never returned when addr == NULL).
371 * Returns -2 on invalid list entry.
372 */
373int
374addr_match_list(const char *addr, const char *_list)
375{
376	char *list, *cp, *o;
377	struct xaddr try_addr, match_addr;
378	u_int masklen, neg;
379	int ret = 0, r;
380
381	if (addr != NULL && addr_pton(addr, &try_addr) != 0) {
382		debug2("%s: couldn't parse address %.100s", __func__, addr);
383		return 0;
384	}
385	if ((o = list = strdup(_list)) == NULL)
386		return -1;
387	while ((cp = strsep(&list, ",")) != NULL) {
388		neg = *cp == '!';
389		if (neg)
390			cp++;
391		if (*cp == '\0') {
392			ret = -2;
393			break;
394		}
395		/* Prefer CIDR address matching */
396		r = addr_pton_cidr(cp, &match_addr, &masklen);
397		if (r == -2) {
398			error("Inconsistent mask length for "
399			    "network \"%.100s\"", cp);
400			ret = -2;
401			break;
402		} else if (r == 0) {
403			if (addr != NULL && addr_netmatch(&try_addr,
404                           &match_addr, masklen) == 0) {
405 foundit:
406				if (neg) {
407					ret = -1;
408					break;
409				}
410				ret = 1;
411			}
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	xfree(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	xfree(o);
494
495	return ret;
496}
497