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 <sys/types.h>
39
40 #include <ctype.h>
41 #include <stdlib.h>
42 #include <string.h>
43 #include <stdarg.h>
44 #include <stdio.h>
45
46 #include "xmalloc.h"
47 #include "match.h"
48 #include "misc.h"
49
50 /*
51 * Returns true if the given string matches the pattern (which may contain ?
52 * and * as wildcards), and zero if it does not match.
53 */
54 int
match_pattern(const char * s,const char * pattern)55 match_pattern(const char *s, const char *pattern)
56 {
57 for (;;) {
58 /* If at end of pattern, accept if also at end of string. */
59 if (!*pattern)
60 return !*s;
61
62 if (*pattern == '*') {
63 /* Skip this and any consecutive asterisks. */
64 while (*pattern == '*')
65 pattern++;
66
67 /* If at end of pattern, accept immediately. */
68 if (!*pattern)
69 return 1;
70
71 /* If next character in pattern is known, optimize. */
72 if (*pattern != '?' && *pattern != '*') {
73 /*
74 * Look instances of the next character in
75 * pattern, and try to match starting from
76 * those.
77 */
78 for (; *s; s++)
79 if (*s == *pattern &&
80 match_pattern(s + 1, pattern + 1))
81 return 1;
82 /* Failed. */
83 return 0;
84 }
85 /*
86 * Move ahead one character at a time and try to
87 * match at each position.
88 */
89 for (; *s; s++)
90 if (match_pattern(s, pattern))
91 return 1;
92 /* Failed. */
93 return 0;
94 }
95 /*
96 * There must be at least one more character in the string.
97 * If we are at the end, fail.
98 */
99 if (!*s)
100 return 0;
101
102 /* Check if the next character of the string is acceptable. */
103 if (*pattern != '?' && *pattern != *s)
104 return 0;
105
106 /* Move to the next character, both in string and in pattern. */
107 s++;
108 pattern++;
109 }
110 /* NOTREACHED */
111 }
112
113 /*
114 * Tries to match the string against the
115 * comma-separated sequence of subpatterns (each possibly preceded by ! to
116 * indicate negation). Returns -1 if negation matches, 1 if there is
117 * a positive match, 0 if there is no match at all.
118 */
119 int
match_pattern_list(const char * string,const char * pattern,int dolower)120 match_pattern_list(const char *string, const char *pattern, int dolower)
121 {
122 char sub[1024];
123 int negated;
124 int got_positive;
125 u_int i, subi, len = strlen(pattern);
126
127 got_positive = 0;
128 for (i = 0; i < len;) {
129 /* Check if the subpattern is negated. */
130 if (pattern[i] == '!') {
131 negated = 1;
132 i++;
133 } else
134 negated = 0;
135
136 /*
137 * Extract the subpattern up to a comma or end. Convert the
138 * subpattern to lowercase.
139 */
140 for (subi = 0;
141 i < len && subi < sizeof(sub) - 1 && pattern[i] != ',';
142 subi++, i++)
143 sub[subi] = dolower && isupper((u_char)pattern[i]) ?
144 tolower((u_char)pattern[i]) : pattern[i];
145 /* If subpattern too long, return failure (no match). */
146 if (subi >= sizeof(sub) - 1)
147 return 0;
148
149 /* If the subpattern was terminated by a comma, then skip it. */
150 if (i < len && pattern[i] == ',')
151 i++;
152
153 /* Null-terminate the subpattern. */
154 sub[subi] = '\0';
155
156 /* Try to match the subpattern against the string. */
157 if (match_pattern(string, sub)) {
158 if (negated)
159 return -1; /* Negative */
160 else
161 got_positive = 1; /* Positive */
162 }
163 }
164
165 /*
166 * Return success if got a positive match. If there was a negative
167 * match, we have already returned -1 and never get here.
168 */
169 return got_positive;
170 }
171
172 /* Match a list representing users or groups. */
173 int
match_usergroup_pattern_list(const char * string,const char * pattern)174 match_usergroup_pattern_list(const char *string, const char *pattern)
175 {
176 /* Case sensitive match */
177 return match_pattern_list(string, pattern, 0);
178 }
179
180 /*
181 * Tries to match the host name (which must be in all lowercase) against the
182 * comma-separated sequence of subpatterns (each possibly preceded by ! to
183 * indicate negation). Returns -1 if negation matches, 1 if there is
184 * a positive match, 0 if there is no match at all.
185 */
186 int
match_hostname(const char * host,const char * pattern)187 match_hostname(const char *host, const char *pattern)
188 {
189 char *hostcopy = xstrdup(host);
190 int r;
191
192 lowercase(hostcopy);
193 r = match_pattern_list(hostcopy, pattern, 1);
194 free(hostcopy);
195 return r;
196 }
197
198 /*
199 * returns 0 if we get a negative match for the hostname or the ip
200 * or if we get no match at all. returns -1 on error, or 1 on
201 * successful match.
202 */
203 int
match_host_and_ip(const char * host,const char * ipaddr,const char * patterns)204 match_host_and_ip(const char *host, const char *ipaddr,
205 const char *patterns)
206 {
207 int mhost, mip;
208
209 if ((mip = addr_match_list(ipaddr, patterns)) == -2)
210 return -1; /* error in ipaddr match */
211 else if (host == NULL || ipaddr == NULL || mip == -1)
212 return 0; /* negative ip address match, or testing pattern */
213
214 /* negative hostname match */
215 if ((mhost = match_hostname(host, patterns)) == -1)
216 return 0;
217 /* no match at all */
218 if (mhost == 0 && mip == 0)
219 return 0;
220 return 1;
221 }
222
223 /*
224 * Match user, user@host_or_ip, user@host_or_ip_list against pattern.
225 * If user, host and ipaddr are all NULL then validate pattern/
226 * Returns -1 on invalid pattern, 0 on no match, 1 on match.
227 */
228 int
match_user(const char * user,const char * host,const char * ipaddr,const char * pattern)229 match_user(const char *user, const char *host, const char *ipaddr,
230 const char *pattern)
231 {
232 char *p, *pat;
233 int ret;
234
235 /* test mode */
236 if (user == NULL && host == NULL && ipaddr == NULL) {
237 if ((p = strchr(pattern, '@')) != NULL &&
238 match_host_and_ip(NULL, NULL, p + 1) < 0)
239 return -1;
240 return 0;
241 }
242
243 if (user == NULL)
244 return 0; /* shouldn't happen */
245
246 if ((p = strchr(pattern, '@')) == NULL)
247 return match_pattern(user, pattern);
248
249 pat = xstrdup(pattern);
250 p = strchr(pat, '@');
251 *p++ = '\0';
252
253 if ((ret = match_pattern(user, pat)) == 1)
254 ret = match_host_and_ip(host, ipaddr, p);
255 free(pat);
256
257 return ret;
258 }
259
260 /*
261 * Returns first item from client-list that is also supported by server-list,
262 * caller must free the returned string.
263 */
264 #define MAX_PROP 40
265 #define SEP ","
266 char *
match_list(const char * client,const char * server,u_int * next)267 match_list(const char *client, const char *server, u_int *next)
268 {
269 char *sproposals[MAX_PROP];
270 char *c, *s, *p, *ret, *cp, *sp;
271 int i, j, nproposals;
272
273 c = cp = xstrdup(client);
274 s = sp = xstrdup(server);
275
276 for ((p = strsep(&sp, SEP)), i=0; p && *p != '\0';
277 (p = strsep(&sp, SEP)), i++) {
278 if (i < MAX_PROP)
279 sproposals[i] = p;
280 else
281 break;
282 }
283 nproposals = i;
284
285 for ((p = strsep(&cp, SEP)), i=0; p && *p != '\0';
286 (p = strsep(&cp, SEP)), i++) {
287 for (j = 0; j < nproposals; j++) {
288 if (strcmp(p, sproposals[j]) == 0) {
289 ret = xstrdup(p);
290 if (next != NULL)
291 *next = (cp == NULL) ?
292 strlen(c) : (u_int)(cp - c);
293 free(c);
294 free(s);
295 return ret;
296 }
297 }
298 }
299 if (next != NULL)
300 *next = strlen(c);
301 free(c);
302 free(s);
303 return NULL;
304 }
305
306 /*
307 * Filter proposal using pattern-list filter.
308 * "denylist" determines sense of filter:
309 * non-zero indicates that items matching filter should be excluded.
310 * zero indicates that only items matching filter should be included.
311 * returns NULL on allocation error, otherwise caller must free result.
312 */
313 static char *
filter_list(const char * proposal,const char * filter,int denylist)314 filter_list(const char *proposal, const char *filter, int denylist)
315 {
316 size_t len = strlen(proposal) + 1;
317 char *fix_prop = malloc(len);
318 char *orig_prop = strdup(proposal);
319 char *cp, *tmp;
320 int r;
321
322 if (fix_prop == NULL || orig_prop == NULL) {
323 free(orig_prop);
324 free(fix_prop);
325 return NULL;
326 }
327
328 tmp = orig_prop;
329 *fix_prop = '\0';
330 while ((cp = strsep(&tmp, ",")) != NULL) {
331 r = match_pattern_list(cp, filter, 0);
332 if ((denylist && r != 1) || (!denylist && r == 1)) {
333 if (*fix_prop != '\0')
334 strlcat(fix_prop, ",", len);
335 strlcat(fix_prop, cp, len);
336 }
337 }
338 free(orig_prop);
339 return fix_prop;
340 }
341
342 /*
343 * Filters a comma-separated list of strings, excluding any entry matching
344 * the 'filter' pattern list. Caller must free returned string.
345 */
346 char *
match_filter_denylist(const char * proposal,const char * filter)347 match_filter_denylist(const char *proposal, const char *filter)
348 {
349 return filter_list(proposal, filter, 1);
350 }
351
352 /*
353 * Filters a comma-separated list of strings, including only entries matching
354 * the 'filter' pattern list. Caller must free returned string.
355 */
356 char *
match_filter_allowlist(const char * proposal,const char * filter)357 match_filter_allowlist(const char *proposal, const char *filter)
358 {
359 return filter_list(proposal, filter, 0);
360 }
361