1 /* $OpenBSD: match.c,v 1.44 2023/04/06 03:19:32 djm Exp $ */
2 /*
3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 * All rights reserved
6 * Simple pattern matching, with '*' and '?' as wildcards.
7 *
8 * As far as I am concerned, the code I have written for this software
9 * can be used freely for any purpose. Any derived versions of this
10 * software must be clearly marked as such, and if the derived work is
11 * incompatible with the protocol description in the RFC file, it must be
12 * called by a name other than "ssh" or "Secure Shell".
13 */
14 /*
15 * Copyright (c) 2000 Markus Friedl. All rights reserved.
16 *
17 * Redistribution and use in source and binary forms, with or without
18 * modification, are permitted provided that the following conditions
19 * are met:
20 * 1. Redistributions of source code must retain the above copyright
21 * notice, this list of conditions and the following disclaimer.
22 * 2. Redistributions in binary form must reproduce the above copyright
23 * notice, this list of conditions and the following disclaimer in the
24 * documentation and/or other materials provided with the distribution.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
27 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
28 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
29 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
30 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
31 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
32 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
33 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
34 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
35 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
36 */
37
38 #include "includes.h"
39
40 #include <sys/types.h>
41
42 #include <ctype.h>
43 #include <stdlib.h>
44 #include <string.h>
45 #include <stdarg.h>
46 #include <stdio.h>
47
48 #include "xmalloc.h"
49 #include "match.h"
50 #include "misc.h"
51
52 /*
53 * Returns true if the given string matches the pattern (which may contain ?
54 * and * as wildcards), and zero if it does not match.
55 */
56 int
match_pattern(const char * s,const char * pattern)57 match_pattern(const char *s, const char *pattern)
58 {
59 for (;;) {
60 /* If at end of pattern, accept if also at end of string. */
61 if (!*pattern)
62 return !*s;
63
64 if (*pattern == '*') {
65 /* Skip this and any consecutive asterisks. */
66 while (*pattern == '*')
67 pattern++;
68
69 /* If at end of pattern, accept immediately. */
70 if (!*pattern)
71 return 1;
72
73 /* If next character in pattern is known, optimize. */
74 if (*pattern != '?' && *pattern != '*') {
75 /*
76 * Look instances of the next character in
77 * pattern, and try to match starting from
78 * those.
79 */
80 for (; *s; s++)
81 if (*s == *pattern &&
82 match_pattern(s + 1, pattern + 1))
83 return 1;
84 /* Failed. */
85 return 0;
86 }
87 /*
88 * Move ahead one character at a time and try to
89 * match at each position.
90 */
91 for (; *s; s++)
92 if (match_pattern(s, pattern))
93 return 1;
94 /* Failed. */
95 return 0;
96 }
97 /*
98 * There must be at least one more character in the string.
99 * If we are at the end, fail.
100 */
101 if (!*s)
102 return 0;
103
104 /* Check if the next character of the string is acceptable. */
105 if (*pattern != '?' && *pattern != *s)
106 return 0;
107
108 /* Move to the next character, both in string and in pattern. */
109 s++;
110 pattern++;
111 }
112 /* NOTREACHED */
113 }
114
115 /*
116 * Tries to match the string against the
117 * comma-separated sequence of subpatterns (each possibly preceded by ! to
118 * indicate negation). Returns -1 if negation matches, 1 if there is
119 * a positive match, 0 if there is no match at all.
120 */
121 int
match_pattern_list(const char * string,const char * pattern,int dolower)122 match_pattern_list(const char *string, const char *pattern, int dolower)
123 {
124 char sub[1024];
125 int negated;
126 int got_positive;
127 u_int i, subi, len = strlen(pattern);
128
129 got_positive = 0;
130 for (i = 0; i < len;) {
131 /* Check if the subpattern is negated. */
132 if (pattern[i] == '!') {
133 negated = 1;
134 i++;
135 } else
136 negated = 0;
137
138 /*
139 * Extract the subpattern up to a comma or end. Convert the
140 * subpattern to lowercase.
141 */
142 for (subi = 0;
143 i < len && subi < sizeof(sub) - 1 && pattern[i] != ',';
144 subi++, i++)
145 sub[subi] = dolower && isupper((u_char)pattern[i]) ?
146 tolower((u_char)pattern[i]) : pattern[i];
147 /* If subpattern too long, return failure (no match). */
148 if (subi >= sizeof(sub) - 1)
149 return 0;
150
151 /* If the subpattern was terminated by a comma, then skip it. */
152 if (i < len && pattern[i] == ',')
153 i++;
154
155 /* Null-terminate the subpattern. */
156 sub[subi] = '\0';
157
158 /* Try to match the subpattern against the string. */
159 if (match_pattern(string, sub)) {
160 if (negated)
161 return -1; /* Negative */
162 else
163 got_positive = 1; /* Positive */
164 }
165 }
166
167 /*
168 * Return success if got a positive match. If there was a negative
169 * match, we have already returned -1 and never get here.
170 */
171 return got_positive;
172 }
173
174 /* Match a list representing users or groups. */
175 int
match_usergroup_pattern_list(const char * string,const char * pattern)176 match_usergroup_pattern_list(const char *string, const char *pattern)
177 {
178 #ifdef HAVE_CYGWIN
179 /* Windows usernames may be Unicode and are not case sensitive */
180 return cygwin_ug_match_pattern_list(string, pattern);
181 #else
182 /* Case sensitive match */
183 return match_pattern_list(string, pattern, 0);
184 #endif
185 }
186
187 /*
188 * Tries to match the host name (which must be in all lowercase) against the
189 * comma-separated sequence of subpatterns (each possibly preceded by ! to
190 * indicate negation). Returns -1 if negation matches, 1 if there is
191 * a positive match, 0 if there is no match at all.
192 */
193 int
match_hostname(const char * host,const char * pattern)194 match_hostname(const char *host, const char *pattern)
195 {
196 char *hostcopy = xstrdup(host);
197 int r;
198
199 lowercase(hostcopy);
200 r = match_pattern_list(hostcopy, pattern, 1);
201 free(hostcopy);
202 return r;
203 }
204
205 /*
206 * returns 0 if we get a negative match for the hostname or the ip
207 * or if we get no match at all. returns -1 on error, or 1 on
208 * successful match.
209 */
210 int
match_host_and_ip(const char * host,const char * ipaddr,const char * patterns)211 match_host_and_ip(const char *host, const char *ipaddr,
212 const char *patterns)
213 {
214 int mhost, mip;
215
216 if ((mip = addr_match_list(ipaddr, patterns)) == -2)
217 return -1; /* error in ipaddr match */
218 else if (host == NULL || ipaddr == NULL || mip == -1)
219 return 0; /* negative ip address match, or testing pattern */
220
221 /* negative hostname match */
222 if ((mhost = match_hostname(host, patterns)) == -1)
223 return 0;
224 /* no match at all */
225 if (mhost == 0 && mip == 0)
226 return 0;
227 return 1;
228 }
229
230 /*
231 * Match user, user@host_or_ip, user@host_or_ip_list against pattern.
232 * If user, host and ipaddr are all NULL then validate pattern/
233 * Returns -1 on invalid pattern, 0 on no match, 1 on match.
234 */
235 int
match_user(const char * user,const char * host,const char * ipaddr,const char * pattern)236 match_user(const char *user, const char *host, const char *ipaddr,
237 const char *pattern)
238 {
239 char *p, *pat;
240 int ret;
241
242 /* test mode */
243 if (user == NULL && host == NULL && ipaddr == NULL) {
244 if ((p = strchr(pattern, '@')) != NULL &&
245 match_host_and_ip(NULL, NULL, p + 1) < 0)
246 return -1;
247 return 0;
248 }
249
250 if (user == NULL)
251 return 0; /* shouldn't happen */
252
253 if ((p = strchr(pattern, '@')) == NULL)
254 return match_pattern(user, pattern);
255
256 pat = xstrdup(pattern);
257 p = strchr(pat, '@');
258 *p++ = '\0';
259
260 if ((ret = match_pattern(user, pat)) == 1)
261 ret = match_host_and_ip(host, ipaddr, p);
262 free(pat);
263
264 return ret;
265 }
266
267 /*
268 * Returns first item from client-list that is also supported by server-list,
269 * caller must free the returned string.
270 */
271 #define MAX_PROP 40
272 #define SEP ","
273 char *
match_list(const char * client,const char * server,u_int * next)274 match_list(const char *client, const char *server, u_int *next)
275 {
276 char *sproposals[MAX_PROP];
277 char *c, *s, *p, *ret, *cp, *sp;
278 int i, j, nproposals;
279
280 c = cp = xstrdup(client);
281 s = sp = xstrdup(server);
282
283 for ((p = strsep(&sp, SEP)), i=0; p && *p != '\0';
284 (p = strsep(&sp, SEP)), i++) {
285 if (i < MAX_PROP)
286 sproposals[i] = p;
287 else
288 break;
289 }
290 nproposals = i;
291
292 for ((p = strsep(&cp, SEP)), i=0; p && *p != '\0';
293 (p = strsep(&cp, SEP)), i++) {
294 for (j = 0; j < nproposals; j++) {
295 if (strcmp(p, sproposals[j]) == 0) {
296 ret = xstrdup(p);
297 if (next != NULL)
298 *next = (cp == NULL) ?
299 strlen(c) : (u_int)(cp - c);
300 free(c);
301 free(s);
302 return ret;
303 }
304 }
305 }
306 if (next != NULL)
307 *next = strlen(c);
308 free(c);
309 free(s);
310 return NULL;
311 }
312
313 /*
314 * Filter proposal using pattern-list filter.
315 * "denylist" determines sense of filter:
316 * non-zero indicates that items matching filter should be excluded.
317 * zero indicates that only items matching filter should be included.
318 * returns NULL on allocation error, otherwise caller must free result.
319 */
320 static char *
filter_list(const char * proposal,const char * filter,int denylist)321 filter_list(const char *proposal, const char *filter, int denylist)
322 {
323 size_t len = strlen(proposal) + 1;
324 char *fix_prop = malloc(len);
325 char *orig_prop = strdup(proposal);
326 char *cp, *tmp;
327 int r;
328
329 if (fix_prop == NULL || orig_prop == NULL) {
330 free(orig_prop);
331 free(fix_prop);
332 return NULL;
333 }
334
335 tmp = orig_prop;
336 *fix_prop = '\0';
337 while ((cp = strsep(&tmp, ",")) != NULL) {
338 r = match_pattern_list(cp, filter, 0);
339 if ((denylist && r != 1) || (!denylist && r == 1)) {
340 if (*fix_prop != '\0')
341 strlcat(fix_prop, ",", len);
342 strlcat(fix_prop, cp, len);
343 }
344 }
345 free(orig_prop);
346 return fix_prop;
347 }
348
349 /*
350 * Filters a comma-separated list of strings, excluding any entry matching
351 * the 'filter' pattern list. Caller must free returned string.
352 */
353 char *
match_filter_denylist(const char * proposal,const char * filter)354 match_filter_denylist(const char *proposal, const char *filter)
355 {
356 return filter_list(proposal, filter, 1);
357 }
358
359 /*
360 * Filters a comma-separated list of strings, including only entries matching
361 * the 'filter' pattern list. Caller must free returned string.
362 */
363 char *
match_filter_allowlist(const char * proposal,const char * filter)364 match_filter_allowlist(const char *proposal, const char *filter)
365 {
366 return filter_list(proposal, filter, 0);
367 }
368