1 /* $OpenBSD: match.c,v 1.37 2017/03/10 04:24:55 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 <stdio.h>
46
47 #include "xmalloc.h"
48 #include "match.h"
49 #include "misc.h"
50
51 /*
52 * Returns true if the given string matches the pattern (which may contain ?
53 * and * as wildcards), and zero if it does not match.
54 */
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 the asterisk. */
66 pattern++;
67
68 /* If at end of pattern, accept immediately. */
69 if (!*pattern)
70 return 1;
71
72 /* If next character in pattern is known, optimize. */
73 if (*pattern != '?' && *pattern != '*') {
74 /*
75 * Look instances of the next character in
76 * pattern, and try to match starting from
77 * those.
78 */
79 for (; *s; s++)
80 if (*s == *pattern &&
81 match_pattern(s + 1, pattern + 1))
82 return 1;
83 /* Failed. */
84 return 0;
85 }
86 /*
87 * Move ahead one character at a time and try to
88 * match at each position.
89 */
90 for (; *s; s++)
91 if (match_pattern(s, pattern))
92 return 1;
93 /* Failed. */
94 return 0;
95 }
96 /*
97 * There must be at least one more character in the string.
98 * If we are at the end, fail.
99 */
100 if (!*s)
101 return 0;
102
103 /* Check if the next character of the string is acceptable. */
104 if (*pattern != '?' && *pattern != *s)
105 return 0;
106
107 /* Move to the next character, both in string and in pattern. */
108 s++;
109 pattern++;
110 }
111 /* NOTREACHED */
112 }
113
114 /*
115 * Tries to match the string against the
116 * comma-separated sequence of subpatterns (each possibly preceded by ! to
117 * indicate negation). Returns -1 if negation matches, 1 if there is
118 * a positive match, 0 if there is no match at all.
119 */
120 int
match_pattern_list(const char * string,const char * pattern,int dolower)121 match_pattern_list(const char *string, const char *pattern, int dolower)
122 {
123 char sub[1024];
124 int negated;
125 int got_positive;
126 u_int i, subi, len = strlen(pattern);
127
128 got_positive = 0;
129 for (i = 0; i < len;) {
130 /* Check if the subpattern is negated. */
131 if (pattern[i] == '!') {
132 negated = 1;
133 i++;
134 } else
135 negated = 0;
136
137 /*
138 * Extract the subpattern up to a comma or end. Convert the
139 * subpattern to lowercase.
140 */
141 for (subi = 0;
142 i < len && subi < sizeof(sub) - 1 && pattern[i] != ',';
143 subi++, i++)
144 sub[subi] = dolower && isupper((u_char)pattern[i]) ?
145 tolower((u_char)pattern[i]) : pattern[i];
146 /* If subpattern too long, return failure (no match). */
147 if (subi >= sizeof(sub) - 1)
148 return 0;
149
150 /* If the subpattern was terminated by a comma, then skip it. */
151 if (i < len && pattern[i] == ',')
152 i++;
153
154 /* Null-terminate the subpattern. */
155 sub[subi] = '\0';
156
157 /* Try to match the subpattern against the string. */
158 if (match_pattern(string, sub)) {
159 if (negated)
160 return -1; /* Negative */
161 else
162 got_positive = 1; /* Positive */
163 }
164 }
165
166 /*
167 * Return success if got a positive match. If there was a negative
168 * match, we have already returned -1 and never get here.
169 */
170 return got_positive;
171 }
172
173 /*
174 * Tries to match the host name (which must be in all lowercase) against the
175 * comma-separated sequence of subpatterns (each possibly preceded by ! to
176 * indicate negation). Returns -1 if negation matches, 1 if there is
177 * a positive match, 0 if there is no match at all.
178 */
179 int
match_hostname(const char * host,const char * pattern)180 match_hostname(const char *host, const char *pattern)
181 {
182 char *hostcopy = xstrdup(host);
183 int r;
184
185 lowercase(hostcopy);
186 r = match_pattern_list(hostcopy, pattern, 1);
187 free(hostcopy);
188 return r;
189 }
190
191 /*
192 * returns 0 if we get a negative match for the hostname or the ip
193 * or if we get no match at all. returns -1 on error, or 1 on
194 * successful match.
195 */
196 int
match_host_and_ip(const char * host,const char * ipaddr,const char * patterns)197 match_host_and_ip(const char *host, const char *ipaddr,
198 const char *patterns)
199 {
200 int mhost, mip;
201
202 if ((mip = addr_match_list(ipaddr, patterns)) == -2)
203 return -1; /* error in ipaddr match */
204 else if (host == NULL || ipaddr == NULL || mip == -1)
205 return 0; /* negative ip address match, or testing pattern */
206
207 /* negative hostname match */
208 if ((mhost = match_hostname(host, patterns)) == -1)
209 return 0;
210 /* no match at all */
211 if (mhost == 0 && mip == 0)
212 return 0;
213 return 1;
214 }
215
216 /*
217 * Match user, user@host_or_ip, user@host_or_ip_list against pattern.
218 * If user, host and ipaddr are all NULL then validate pattern/
219 * Returns -1 on invalid pattern, 0 on no match, 1 on match.
220 */
221 int
match_user(const char * user,const char * host,const char * ipaddr,const char * pattern)222 match_user(const char *user, const char *host, const char *ipaddr,
223 const char *pattern)
224 {
225 char *p, *pat;
226 int ret;
227
228 /* test mode */
229 if (user == NULL && host == NULL && ipaddr == NULL) {
230 if ((p = strchr(pattern, '@')) != NULL &&
231 match_host_and_ip(NULL, NULL, p + 1) < 0)
232 return -1;
233 return 0;
234 }
235
236 if ((p = strchr(pattern,'@')) == NULL)
237 return match_pattern(user, pattern);
238
239 pat = xstrdup(pattern);
240 p = strchr(pat, '@');
241 *p++ = '\0';
242
243 if ((ret = match_pattern(user, pat)) == 1)
244 ret = match_host_and_ip(host, ipaddr, p);
245 free(pat);
246
247 return ret;
248 }
249
250 /*
251 * Returns first item from client-list that is also supported by server-list,
252 * caller must free the returned string.
253 */
254 #define MAX_PROP 40
255 #define SEP ","
256 char *
match_list(const char * client,const char * server,u_int * next)257 match_list(const char *client, const char *server, u_int *next)
258 {
259 char *sproposals[MAX_PROP];
260 char *c, *s, *p, *ret, *cp, *sp;
261 int i, j, nproposals;
262
263 c = cp = xstrdup(client);
264 s = sp = xstrdup(server);
265
266 for ((p = strsep(&sp, SEP)), i=0; p && *p != '\0';
267 (p = strsep(&sp, SEP)), i++) {
268 if (i < MAX_PROP)
269 sproposals[i] = p;
270 else
271 break;
272 }
273 nproposals = i;
274
275 for ((p = strsep(&cp, SEP)), i=0; p && *p != '\0';
276 (p = strsep(&cp, SEP)), i++) {
277 for (j = 0; j < nproposals; j++) {
278 if (strcmp(p, sproposals[j]) == 0) {
279 ret = xstrdup(p);
280 if (next != NULL)
281 *next = (cp == NULL) ?
282 strlen(c) : (u_int)(cp - c);
283 free(c);
284 free(s);
285 return ret;
286 }
287 }
288 }
289 if (next != NULL)
290 *next = strlen(c);
291 free(c);
292 free(s);
293 return NULL;
294 }
295
296 /*
297 * Filters a comma-separated list of strings, excluding any entry matching
298 * the 'filter' pattern list. Caller must free returned string.
299 */
300 char *
match_filter_list(const char * proposal,const char * filter)301 match_filter_list(const char *proposal, const char *filter)
302 {
303 size_t len = strlen(proposal) + 1;
304 char *fix_prop = malloc(len);
305 char *orig_prop = strdup(proposal);
306 char *cp, *tmp;
307
308 if (fix_prop == NULL || orig_prop == NULL) {
309 free(orig_prop);
310 free(fix_prop);
311 return NULL;
312 }
313
314 tmp = orig_prop;
315 *fix_prop = '\0';
316 while ((cp = strsep(&tmp, ",")) != NULL) {
317 if (match_pattern_list(cp, filter, 0) != 1) {
318 if (*fix_prop != '\0')
319 strlcat(fix_prop, ",", len);
320 strlcat(fix_prop, cp, len);
321 }
322 }
323 free(orig_prop);
324 return fix_prop;
325 }
326
327