1 /* $OpenBSD: match.c,v 1.39 2019/03/06 22:14:23 dtucker 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 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 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 /* Match a list representing users or groups. */ 174 int 175 match_usergroup_pattern_list(const char *string, const char *pattern) 176 { 177 #ifdef HAVE_CYGWIN 178 /* Windows usernames may be Unicode and are not case sensitive */ 179 return cygwin_ug_match_pattern_list(string, pattern); 180 #else 181 /* Case insensitive match */ 182 return match_pattern_list(string, pattern, 0); 183 #endif 184 } 185 186 /* 187 * Tries to match the host name (which must be in all lowercase) against the 188 * comma-separated sequence of subpatterns (each possibly preceded by ! to 189 * indicate negation). Returns -1 if negation matches, 1 if there is 190 * a positive match, 0 if there is no match at all. 191 */ 192 int 193 match_hostname(const char *host, const char *pattern) 194 { 195 char *hostcopy = xstrdup(host); 196 int r; 197 198 lowercase(hostcopy); 199 r = match_pattern_list(hostcopy, pattern, 1); 200 free(hostcopy); 201 return r; 202 } 203 204 /* 205 * returns 0 if we get a negative match for the hostname or the ip 206 * or if we get no match at all. returns -1 on error, or 1 on 207 * successful match. 208 */ 209 int 210 match_host_and_ip(const char *host, const char *ipaddr, 211 const char *patterns) 212 { 213 int mhost, mip; 214 215 if ((mip = addr_match_list(ipaddr, patterns)) == -2) 216 return -1; /* error in ipaddr match */ 217 else if (host == NULL || ipaddr == NULL || mip == -1) 218 return 0; /* negative ip address match, or testing pattern */ 219 220 /* negative hostname match */ 221 if ((mhost = match_hostname(host, patterns)) == -1) 222 return 0; 223 /* no match at all */ 224 if (mhost == 0 && mip == 0) 225 return 0; 226 return 1; 227 } 228 229 /* 230 * Match user, user@host_or_ip, user@host_or_ip_list against pattern. 231 * If user, host and ipaddr are all NULL then validate pattern/ 232 * Returns -1 on invalid pattern, 0 on no match, 1 on match. 233 */ 234 int 235 match_user(const char *user, const char *host, const char *ipaddr, 236 const char *pattern) 237 { 238 char *p, *pat; 239 int ret; 240 241 /* test mode */ 242 if (user == NULL && host == NULL && ipaddr == NULL) { 243 if ((p = strchr(pattern, '@')) != NULL && 244 match_host_and_ip(NULL, NULL, p + 1) < 0) 245 return -1; 246 return 0; 247 } 248 249 if ((p = strchr(pattern,'@')) == NULL) 250 return match_pattern(user, pattern); 251 252 pat = xstrdup(pattern); 253 p = strchr(pat, '@'); 254 *p++ = '\0'; 255 256 if ((ret = match_pattern(user, pat)) == 1) 257 ret = match_host_and_ip(host, ipaddr, p); 258 free(pat); 259 260 return ret; 261 } 262 263 /* 264 * Returns first item from client-list that is also supported by server-list, 265 * caller must free the returned string. 266 */ 267 #define MAX_PROP 40 268 #define SEP "," 269 char * 270 match_list(const char *client, const char *server, u_int *next) 271 { 272 char *sproposals[MAX_PROP]; 273 char *c, *s, *p, *ret, *cp, *sp; 274 int i, j, nproposals; 275 276 c = cp = xstrdup(client); 277 s = sp = xstrdup(server); 278 279 for ((p = strsep(&sp, SEP)), i=0; p && *p != '\0'; 280 (p = strsep(&sp, SEP)), i++) { 281 if (i < MAX_PROP) 282 sproposals[i] = p; 283 else 284 break; 285 } 286 nproposals = i; 287 288 for ((p = strsep(&cp, SEP)), i=0; p && *p != '\0'; 289 (p = strsep(&cp, SEP)), i++) { 290 for (j = 0; j < nproposals; j++) { 291 if (strcmp(p, sproposals[j]) == 0) { 292 ret = xstrdup(p); 293 if (next != NULL) 294 *next = (cp == NULL) ? 295 strlen(c) : (u_int)(cp - c); 296 free(c); 297 free(s); 298 return ret; 299 } 300 } 301 } 302 if (next != NULL) 303 *next = strlen(c); 304 free(c); 305 free(s); 306 return NULL; 307 } 308 309 /* 310 * Filter proposal using pattern-list filter. 311 * "blacklist" determines sense of filter: 312 * non-zero indicates that items matching filter should be excluded. 313 * zero indicates that only items matching filter should be included. 314 * returns NULL on allocation error, otherwise caller must free result. 315 */ 316 static char * 317 filter_list(const char *proposal, const char *filter, int blacklist) 318 { 319 size_t len = strlen(proposal) + 1; 320 char *fix_prop = malloc(len); 321 char *orig_prop = strdup(proposal); 322 char *cp, *tmp; 323 int r; 324 325 if (fix_prop == NULL || orig_prop == NULL) { 326 free(orig_prop); 327 free(fix_prop); 328 return NULL; 329 } 330 331 tmp = orig_prop; 332 *fix_prop = '\0'; 333 while ((cp = strsep(&tmp, ",")) != NULL) { 334 r = match_pattern_list(cp, filter, 0); 335 if ((blacklist && r != 1) || (!blacklist && r == 1)) { 336 if (*fix_prop != '\0') 337 strlcat(fix_prop, ",", len); 338 strlcat(fix_prop, cp, len); 339 } 340 } 341 free(orig_prop); 342 return fix_prop; 343 } 344 345 /* 346 * Filters a comma-separated list of strings, excluding any entry matching 347 * the 'filter' pattern list. Caller must free returned string. 348 */ 349 char * 350 match_filter_blacklist(const char *proposal, const char *filter) 351 { 352 return filter_list(proposal, filter, 1); 353 } 354 355 /* 356 * Filters a comma-separated list of strings, including only entries matching 357 * the 'filter' pattern list. Caller must free returned string. 358 */ 359 char * 360 match_filter_whitelist(const char *proposal, const char *filter) 361 { 362 return filter_list(proposal, filter, 0); 363 } 364