addrmatch.c revision 1.15 
1/*	$OpenBSD: addrmatch.c,v 1.15 2020/10/18 11:32:01 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 = NULL;
205	int ret = -1;
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		goto out;
212	if (ai == NULL || ai->ai_addr == NULL)
213		goto out;
214	if (n != NULL && addr_sa_to_xaddr(ai->ai_addr, ai->ai_addrlen, n) == -1)
215		goto out;
216	/* success */
217	ret = 0;
218 out:
219	if (ai != NULL)
220		freeaddrinfo(ai);
221	return ret;
222}
223
224/*
225 * Perform bitwise negation of address
226 * Returns 0 on success, -1 on failure.
227 */
228static int
229addr_invert(struct xaddr *n)
230{
231	int i;
232
233	if (n == NULL)
234		return (-1);
235
236	switch (n->af) {
237	case AF_INET:
238		n->v4.s_addr = ~n->v4.s_addr;
239		return (0);
240	case AF_INET6:
241		for (i = 0; i < 4; i++)
242			n->addr32[i] = ~n->addr32[i];
243		return (0);
244	default:
245		return (-1);
246	}
247}
248
249/*
250 * Calculate a netmask of length 'l' for address family 'af' and
251 * store it in 'n'.
252 * Returns 0 on success, -1 on failure.
253 */
254static int
255addr_hostmask(int af, u_int l, struct xaddr *n)
256{
257	if (addr_netmask(af, l, n) == -1 || addr_invert(n) == -1)
258		return (-1);
259	return (0);
260}
261
262/*
263 * Test whether address 'a' is all zeros (i.e. 0.0.0.0 or ::)
264 * Returns 0 on if address is all-zeros, -1 if not all zeros or on failure.
265 */
266static int
267addr_is_all0s(const struct xaddr *a)
268{
269	int i;
270
271	switch (a->af) {
272	case AF_INET:
273		return (a->v4.s_addr == 0 ? 0 : -1);
274	case AF_INET6:;
275		for (i = 0; i < 4; i++)
276			if (a->addr32[i] != 0)
277				return (-1);
278		return (0);
279	default:
280		return (-1);
281	}
282}
283
284/*
285 * Test whether host portion of address 'a', as determined by 'masklen'
286 * is all zeros.
287 * Returns 0 on if host portion of address is all-zeros,
288 * -1 if not all zeros or on failure.
289 */
290static int
291addr_host_is_all0s(const struct xaddr *a, u_int masklen)
292{
293	struct xaddr tmp_addr, tmp_mask, tmp_result;
294
295	memcpy(&tmp_addr, a, sizeof(tmp_addr));
296	if (addr_hostmask(a->af, masklen, &tmp_mask) == -1)
297		return (-1);
298	if (addr_and(&tmp_result, &tmp_addr, &tmp_mask) == -1)
299		return (-1);
300	return (addr_is_all0s(&tmp_result));
301}
302
303/*
304 * Parse a CIDR address (x.x.x.x/y or xxxx:yyyy::/z).
305 * Return -1 on parse error, -2 on inconsistency or 0 on success.
306 */
307static int
308addr_pton_cidr(const char *p, struct xaddr *n, u_int *l)
309{
310	struct xaddr tmp;
311	long unsigned int masklen = 999;
312	char addrbuf[64], *mp, *cp;
313
314	/* Don't modify argument */
315	if (p == NULL || strlcpy(addrbuf, p, sizeof(addrbuf)) >= sizeof(addrbuf))
316		return -1;
317
318	if ((mp = strchr(addrbuf, '/')) != NULL) {
319		*mp = '\0';
320		mp++;
321		masklen = strtoul(mp, &cp, 10);
322		if (*mp == '\0' || *cp != '\0' || masklen > 128)
323			return -1;
324	}
325
326	if (addr_pton(addrbuf, &tmp) == -1)
327		return -1;
328
329	if (mp == NULL)
330		masklen = addr_unicast_masklen(tmp.af);
331	if (masklen_valid(tmp.af, masklen) == -1)
332		return -2;
333	if (addr_host_is_all0s(&tmp, masklen) != 0)
334		return -2;
335
336	if (n != NULL)
337		memcpy(n, &tmp, sizeof(*n));
338	if (l != NULL)
339		*l = masklen;
340
341	return 0;
342}
343
344static int
345addr_netmatch(const struct xaddr *host, const struct xaddr *net, u_int masklen)
346{
347	struct xaddr tmp_mask, tmp_result;
348
349	if (host->af != net->af)
350		return -1;
351
352	if (addr_netmask(host->af, masklen, &tmp_mask) == -1)
353		return -1;
354	if (addr_and(&tmp_result, host, &tmp_mask) == -1)
355		return -1;
356	return addr_cmp(&tmp_result, net);
357}
358
359/*
360 * Match "addr" against list pattern list "_list", which may contain a
361 * mix of CIDR addresses and old-school wildcards.
362 *
363 * If addr is NULL, then no matching is performed, but _list is parsed
364 * and checked for well-formedness.
365 *
366 * Returns 1 on match found (never returned when addr == NULL).
367 * Returns 0 on if no match found, or no errors found when addr == NULL.
368 * Returns -1 on negated match found (never returned when addr == NULL).
369 * Returns -2 on invalid list entry.
370 */
371int
372addr_match_list(const char *addr, const char *_list)
373{
374	char *list, *cp, *o;
375	struct xaddr try_addr, match_addr;
376	u_int masklen, neg;
377	int ret = 0, r;
378
379	if (addr != NULL && addr_pton(addr, &try_addr) != 0) {
380		debug2_f("couldn't parse address %.100s", addr);
381		return 0;
382	}
383	if ((o = list = strdup(_list)) == NULL)
384		return -1;
385	while ((cp = strsep(&list, ",")) != NULL) {
386		neg = *cp == '!';
387		if (neg)
388			cp++;
389		if (*cp == '\0') {
390			ret = -2;
391			break;
392		}
393		/* Prefer CIDR address matching */
394		r = addr_pton_cidr(cp, &match_addr, &masklen);
395		if (r == -2) {
396			debug2_f("inconsistent mask length for "
397			    "match network \"%.100s\"", cp);
398			ret = -2;
399			break;
400		} else if (r == 0) {
401			if (addr != NULL && addr_netmatch(&try_addr,
402                           &match_addr, masklen) == 0) {
403 foundit:
404				if (neg) {
405					ret = -1;
406					break;
407				}
408				ret = 1;
409			}
410			continue;
411		} else {
412			/* If CIDR parse failed, try wildcard string match */
413			if (addr != NULL && match_pattern(addr, cp) == 1)
414				goto foundit;
415		}
416	}
417	free(o);
418
419	return ret;
420}
421
422/*
423 * Match "addr" against list CIDR list "_list". Lexical wildcards and
424 * negation are not supported. If "addr" == NULL, will verify structure
425 * of "_list".
426 *
427 * Returns 1 on match found (never returned when addr == NULL).
428 * Returns 0 on if no match found, or no errors found when addr == NULL.
429 * Returns -1 on error
430 */
431int
432addr_match_cidr_list(const char *addr, const char *_list)
433{
434	char *list, *cp, *o;
435	struct xaddr try_addr, match_addr;
436	u_int masklen;
437	int ret = 0, r;
438
439	if (addr != NULL && addr_pton(addr, &try_addr) != 0) {
440		debug2_f("couldn't parse address %.100s", addr);
441		return 0;
442	}
443	if ((o = list = strdup(_list)) == NULL)
444		return -1;
445	while ((cp = strsep(&list, ",")) != NULL) {
446		if (*cp == '\0') {
447			error_f("empty entry in list \"%.100s\"", o);
448			ret = -1;
449			break;
450		}
451
452		/*
453		 * NB. This function is called in pre-auth with untrusted data,
454		 * so be extra paranoid about junk reaching getaddrino (via
455		 * addr_pton_cidr).
456		 */
457
458		/* Stop junk from reaching getaddrinfo. +3 is for masklen */
459		if (strlen(cp) > INET6_ADDRSTRLEN + 3) {
460			error_f("list entry \"%.100s\" too long", cp);
461			ret = -1;
462			break;
463		}
464#define VALID_CIDR_CHARS "0123456789abcdefABCDEF.:/"
465		if (strspn(cp, VALID_CIDR_CHARS) != strlen(cp)) {
466			error_f("list entry \"%.100s\" contains invalid "
467			    "characters", cp);
468			ret = -1;
469		}
470
471		/* Prefer CIDR address matching */
472		r = addr_pton_cidr(cp, &match_addr, &masklen);
473		if (r == -1) {
474			error("Invalid network entry \"%.100s\"", cp);
475			ret = -1;
476			break;
477		} else if (r == -2) {
478			error("Inconsistent mask length for "
479			    "network \"%.100s\"", cp);
480			ret = -1;
481			break;
482		} else if (r == 0 && addr != NULL) {
483			if (addr_netmatch(&try_addr, &match_addr,
484			    masklen) == 0)
485				ret = 1;
486			continue;
487		}
488	}
489	free(o);
490
491	return ret;
492}
493