addrmatch.c revision 262566 
1/*	$OpenBSD: addrmatch.c,v 1.9 2014/01/19 11:21:51 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 "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#include "xmalloc.h"
35
36struct xaddr {
37	sa_family_t	af;
38	union {
39		struct in_addr		v4;
40		struct in6_addr		v6;
41		u_int8_t		addr8[16];
42		u_int32_t		addr32[4];
43	} xa;		    /* 128-bit address */
44	u_int32_t	scope_id;	/* iface scope id for v6 */
45#define v4	xa.v4
46#define v6	xa.v6
47#define addr8	xa.addr8
48#define addr32	xa.addr32
49};
50
51static int
52addr_unicast_masklen(int af)
53{
54	switch (af) {
55	case AF_INET:
56		return 32;
57	case AF_INET6:
58		return 128;
59	default:
60		return -1;
61	}
62}
63
64static inline int
65masklen_valid(int af, u_int masklen)
66{
67	switch (af) {
68	case AF_INET:
69		return masklen <= 32 ? 0 : -1;
70	case AF_INET6:
71		return masklen <= 128 ? 0 : -1;
72	default:
73		return -1;
74	}
75}
76
77/*
78 * Convert struct sockaddr to struct xaddr
79 * Returns 0 on success, -1 on failure.
80 */
81static int
82addr_sa_to_xaddr(struct sockaddr *sa, socklen_t slen, struct xaddr *xa)
83{
84	struct sockaddr_in *in4 = (struct sockaddr_in *)sa;
85	struct sockaddr_in6 *in6 = (struct sockaddr_in6 *)sa;
86
87	memset(xa, '\0', sizeof(*xa));
88
89	switch (sa->sa_family) {
90	case AF_INET:
91		if (slen < (socklen_t)sizeof(*in4))
92			return -1;
93		xa->af = AF_INET;
94		memcpy(&xa->v4, &in4->sin_addr, sizeof(xa->v4));
95		break;
96	case AF_INET6:
97		if (slen < (socklen_t)sizeof(*in6))
98			return -1;
99		xa->af = AF_INET6;
100		memcpy(&xa->v6, &in6->sin6_addr, sizeof(xa->v6));
101#ifdef HAVE_STRUCT_SOCKADDR_IN6_SIN6_SCOPE_ID
102		xa->scope_id = in6->sin6_scope_id;
103#endif
104		break;
105	default:
106		return -1;
107	}
108
109	return 0;
110}
111
112/*
113 * Calculate a netmask of length 'l' for address family 'af' and
114 * store it in 'n'.
115 * Returns 0 on success, -1 on failure.
116 */
117static int
118addr_netmask(int af, u_int l, struct xaddr *n)
119{
120	int i;
121
122	if (masklen_valid(af, l) != 0 || n == NULL)
123		return -1;
124
125	memset(n, '\0', sizeof(*n));
126	switch (af) {
127	case AF_INET:
128		n->af = AF_INET;
129		if (l == 0)
130			return 0;
131		n->v4.s_addr = htonl((0xffffffff << (32 - l)) & 0xffffffff);
132		return 0;
133	case AF_INET6:
134		n->af = AF_INET6;
135		for (i = 0; i < 4 && l >= 32; i++, l -= 32)
136			n->addr32[i] = 0xffffffffU;
137		if (i < 4 && l != 0)
138			n->addr32[i] = htonl((0xffffffff << (32 - l)) &
139			    0xffffffff);
140		return 0;
141	default:
142		return -1;
143	}
144}
145
146/*
147 * Perform logical AND of addresses 'a' and 'b', storing result in 'dst'.
148 * Returns 0 on success, -1 on failure.
149 */
150static int
151addr_and(struct xaddr *dst, const struct xaddr *a, const struct xaddr *b)
152{
153	int i;
154
155	if (dst == NULL || a == NULL || b == NULL || a->af != b->af)
156		return -1;
157
158	memcpy(dst, a, sizeof(*dst));
159	switch (a->af) {
160	case AF_INET:
161		dst->v4.s_addr &= b->v4.s_addr;
162		return 0;
163	case AF_INET6:
164		dst->scope_id = a->scope_id;
165		for (i = 0; i < 4; i++)
166			dst->addr32[i] &= b->addr32[i];
167		return 0;
168	default:
169		return -1;
170	}
171}
172
173/*
174 * Compare addresses 'a' and 'b'
175 * Return 0 if addresses are identical, -1 if (a < b) or 1 if (a > b)
176 */
177static int
178addr_cmp(const struct xaddr *a, const struct xaddr *b)
179{
180	int i;
181
182	if (a->af != b->af)
183		return a->af == AF_INET6 ? 1 : -1;
184
185	switch (a->af) {
186	case AF_INET:
187		if (a->v4.s_addr == b->v4.s_addr)
188			return 0;
189		return ntohl(a->v4.s_addr) > ntohl(b->v4.s_addr) ? 1 : -1;
190	case AF_INET6:
191		for (i = 0; i < 16; i++)
192			if (a->addr8[i] - b->addr8[i] != 0)
193				return a->addr8[i] > b->addr8[i] ? 1 : -1;
194		if (a->scope_id == b->scope_id)
195			return 0;
196		return a->scope_id > b->scope_id ? 1 : -1;
197	default:
198		return -1;
199	}
200}
201
202/*
203 * Parse string address 'p' into 'n'
204 * Returns 0 on success, -1 on failure.
205 */
206static int
207addr_pton(const char *p, struct xaddr *n)
208{
209	struct addrinfo hints, *ai;
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		return -1;
216
217	if (ai == NULL || ai->ai_addr == NULL)
218		return -1;
219
220	if (n != NULL &&
221	    addr_sa_to_xaddr(ai->ai_addr, ai->ai_addrlen, n) == -1) {
222		freeaddrinfo(ai);
223		return -1;
224	}
225
226	freeaddrinfo(ai);
227	return 0;
228}
229
230/*
231 * Perform bitwise negation of address
232 * Returns 0 on success, -1 on failure.
233 */
234static int
235addr_invert(struct xaddr *n)
236{
237	int i;
238
239	if (n == NULL)
240		return (-1);
241
242	switch (n->af) {
243	case AF_INET:
244		n->v4.s_addr = ~n->v4.s_addr;
245		return (0);
246	case AF_INET6:
247		for (i = 0; i < 4; i++)
248			n->addr32[i] = ~n->addr32[i];
249		return (0);
250	default:
251		return (-1);
252	}
253}
254
255/*
256 * Calculate a netmask of length 'l' for address family 'af' and
257 * store it in 'n'.
258 * Returns 0 on success, -1 on failure.
259 */
260static int
261addr_hostmask(int af, u_int l, struct xaddr *n)
262{
263	if (addr_netmask(af, l, n) == -1 || addr_invert(n) == -1)
264		return (-1);
265	return (0);
266}
267
268/*
269 * Test whether address 'a' is all zeros (i.e. 0.0.0.0 or ::)
270 * Returns 0 on if address is all-zeros, -1 if not all zeros or on failure.
271 */
272static int
273addr_is_all0s(const struct xaddr *a)
274{
275	int i;
276
277	switch (a->af) {
278	case AF_INET:
279		return (a->v4.s_addr == 0 ? 0 : -1);
280	case AF_INET6:;
281		for (i = 0; i < 4; i++)
282			if (a->addr32[i] != 0)
283				return (-1);
284		return (0);
285	default:
286		return (-1);
287	}
288}
289
290/*
291 * Test whether host portion of address 'a', as determined by 'masklen'
292 * is all zeros.
293 * Returns 0 on if host portion of address is all-zeros,
294 * -1 if not all zeros or on failure.
295 */
296static int
297addr_host_is_all0s(const struct xaddr *a, u_int masklen)
298{
299	struct xaddr tmp_addr, tmp_mask, tmp_result;
300
301	memcpy(&tmp_addr, a, sizeof(tmp_addr));
302	if (addr_hostmask(a->af, masklen, &tmp_mask) == -1)
303		return (-1);
304	if (addr_and(&tmp_result, &tmp_addr, &tmp_mask) == -1)
305		return (-1);
306	return (addr_is_all0s(&tmp_result));
307}
308
309/*
310 * Parse a CIDR address (x.x.x.x/y or xxxx:yyyy::/z).
311 * Return -1 on parse error, -2 on inconsistency or 0 on success.
312 */
313static int
314addr_pton_cidr(const char *p, struct xaddr *n, u_int *l)
315{
316	struct xaddr tmp;
317	long unsigned int masklen = 999;
318	char addrbuf[64], *mp, *cp;
319
320	/* Don't modify argument */
321	if (p == NULL || strlcpy(addrbuf, p, sizeof(addrbuf)) >= sizeof(addrbuf))
322		return -1;
323
324	if ((mp = strchr(addrbuf, '/')) != NULL) {
325		*mp = '\0';
326		mp++;
327		masklen = strtoul(mp, &cp, 10);
328		if (*mp == '\0' || *cp != '\0' || masklen > 128)
329			return -1;
330	}
331
332	if (addr_pton(addrbuf, &tmp) == -1)
333		return -1;
334
335	if (mp == NULL)
336		masklen = addr_unicast_masklen(tmp.af);
337	if (masklen_valid(tmp.af, masklen) == -1)
338		return -2;
339	if (addr_host_is_all0s(&tmp, masklen) != 0)
340		return -2;
341
342	if (n != NULL)
343		memcpy(n, &tmp, sizeof(*n));
344	if (l != NULL)
345		*l = masklen;
346
347	return 0;
348}
349
350static int
351addr_netmatch(const struct xaddr *host, const struct xaddr *net, u_int masklen)
352{
353	struct xaddr tmp_mask, tmp_result;
354
355	if (host->af != net->af)
356		return -1;
357
358	if (addr_netmask(host->af, masklen, &tmp_mask) == -1)
359		return -1;
360	if (addr_and(&tmp_result, host, &tmp_mask) == -1)
361		return -1;
362	return addr_cmp(&tmp_result, net);
363}
364
365/*
366 * Match "addr" against list pattern list "_list", which may contain a
367 * mix of CIDR addresses and old-school wildcards.
368 *
369 * If addr is NULL, then no matching is performed, but _list is parsed
370 * and checked for well-formedness.
371 *
372 * Returns 1 on match found (never returned when addr == NULL).
373 * Returns 0 on if no match found, or no errors found when addr == NULL.
374 * Returns -1 on negated match found (never returned when addr == NULL).
375 * Returns -2 on invalid list entry.
376 */
377int
378addr_match_list(const char *addr, const char *_list)
379{
380	char *list, *cp, *o;
381	struct xaddr try_addr, match_addr;
382	u_int masklen, neg;
383	int ret = 0, r;
384
385	if (addr != NULL && addr_pton(addr, &try_addr) != 0) {
386		debug2("%s: couldn't parse address %.100s", __func__, addr);
387		return 0;
388	}
389	if ((o = list = strdup(_list)) == NULL)
390		return -1;
391	while ((cp = strsep(&list, ",")) != NULL) {
392		neg = *cp == '!';
393		if (neg)
394			cp++;
395		if (*cp == '\0') {
396			ret = -2;
397			break;
398		}
399		/* Prefer CIDR address matching */
400		r = addr_pton_cidr(cp, &match_addr, &masklen);
401		if (r == -2) {
402			error("Inconsistent mask length for "
403			    "network \"%.100s\"", cp);
404			ret = -2;
405			break;
406		} else if (r == 0) {
407			if (addr != NULL && addr_netmatch(&try_addr,
408                           &match_addr, masklen) == 0) {
409 foundit:
410				if (neg) {
411					ret = -1;
412					break;
413				}
414				ret = 1;
415			}
416			continue;
417		} else {
418			/* If CIDR parse failed, try wildcard string match */
419			if (addr != NULL && match_pattern(addr, cp) == 1)
420				goto foundit;
421		}
422	}
423	free(o);
424
425	return ret;
426}
427
428/*
429 * Match "addr" against list CIDR list "_list". Lexical wildcards and
430 * negation are not supported. If "addr" == NULL, will verify structure
431 * of "_list".
432 *
433 * Returns 1 on match found (never returned when addr == NULL).
434 * Returns 0 on if no match found, or no errors found when addr == NULL.
435 * Returns -1 on error
436 */
437int
438addr_match_cidr_list(const char *addr, const char *_list)
439{
440	char *list, *cp, *o;
441	struct xaddr try_addr, match_addr;
442	u_int masklen;
443	int ret = 0, r;
444
445	if (addr != NULL && addr_pton(addr, &try_addr) != 0) {
446		debug2("%s: couldn't parse address %.100s", __func__, addr);
447		return 0;
448	}
449	if ((o = list = strdup(_list)) == NULL)
450		return -1;
451	while ((cp = strsep(&list, ",")) != NULL) {
452		if (*cp == '\0') {
453			error("%s: empty entry in list \"%.100s\"",
454			    __func__, o);
455			ret = -1;
456			break;
457		}
458
459		/*
460		 * NB. This function is called in pre-auth with untrusted data,
461		 * so be extra paranoid about junk reaching getaddrino (via
462		 * addr_pton_cidr).
463		 */
464
465		/* Stop junk from reaching getaddrinfo. +3 is for masklen */
466		if (strlen(cp) > INET6_ADDRSTRLEN + 3) {
467			error("%s: list entry \"%.100s\" too long",
468			    __func__, cp);
469			ret = -1;
470			break;
471		}
472#define VALID_CIDR_CHARS "0123456789abcdefABCDEF.:/"
473		if (strspn(cp, VALID_CIDR_CHARS) != strlen(cp)) {
474			error("%s: list entry \"%.100s\" contains invalid "
475			    "characters", __func__, cp);
476			ret = -1;
477		}
478
479		/* Prefer CIDR address matching */
480		r = addr_pton_cidr(cp, &match_addr, &masklen);
481		if (r == -1) {
482			error("Invalid network entry \"%.100s\"", cp);
483			ret = -1;
484			break;
485		} else if (r == -2) {
486			error("Inconsistent mask length for "
487			    "network \"%.100s\"", cp);
488			ret = -1;
489			break;
490		} else if (r == 0 && addr != NULL) {
491			if (addr_netmatch(&try_addr, &match_addr,
492			    masklen) == 0)
493				ret = 1;
494			continue;
495		}
496	}
497	free(o);
498
499	return ret;
500}
501