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 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 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 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 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 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 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 * 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 * 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 * 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 * 364 match_filter_allowlist(const char *proposal, const char *filter) 365 { 366 return filter_list(proposal, filter, 0); 367 } 368