1 /* $NetBSD: match.c,v 1.18 2026/09/21 21:30:59 christos Exp $ */ 2 /* $OpenBSD: match.c,v 1.46 2026/05/31 04:19:16 djm Exp $ */ 3 4 /* 5 * Author: Tatu Ylonen <ylo (at) cs.hut.fi> 6 * Copyright (c) 1995 Tatu Ylonen <ylo (at) cs.hut.fi>, Espoo, Finland 7 * All rights reserved 8 * Simple pattern matching, with '*' and '?' as wildcards. 9 * 10 * As far as I am concerned, the code I have written for this software 11 * can be used freely for any purpose. Any derived versions of this 12 * software must be clearly marked as such, and if the derived work is 13 * incompatible with the protocol description in the RFC file, it must be 14 * called by a name other than "ssh" or "Secure Shell". 15 */ 16 /* 17 * Copyright (c) 2000 Markus Friedl. All rights reserved. 18 * Copyright (c) 2026 Damien Miller. All rights reserved. 19 * 20 * Redistribution and use in source and binary forms, with or without 21 * modification, are permitted provided that the following conditions 22 * are met: 23 * 1. Redistributions of source code must retain the above copyright 24 * notice, this list of conditions and the following disclaimer. 25 * 2. Redistributions in binary form must reproduce the above copyright 26 * notice, this list of conditions and the following disclaimer in the 27 * documentation and/or other materials provided with the distribution. 28 * 29 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 30 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 31 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 32 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 33 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 34 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 35 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 36 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 37 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 38 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 39 */ 40 41 #include "includes.h" 42 __RCSID("$NetBSD: match.c,v 1.18 2026/09/21 21:30:59 christos Exp $"); 43 #include <sys/types.h> 44 45 #include <ctype.h> 46 #include <stdlib.h> 47 #include <string.h> 48 #include <stdarg.h> 49 #include <stdio.h> 50 51 #include "xmalloc.h" 52 #include "match.h" 53 #include "misc.h" 54 55 /* 56 * Computes the epsilon closure of an NFA set. 57 * In our wildcard grammar, epsilon transitions only exist for '*' wildcards, 58 * allowing us to transition from state i to i+1 without consuming input. 59 * 60 * This function modifies 'states' in place. 61 */ 62 static void 63 epsilon_closure(char *states, const char *pattern, size_t M) 64 { 65 size_t i; 66 67 /* only need a forward pass as there are no back jumps in our grammar */ 68 for (i = 0; i < M; i++) { 69 if (!states[i] || pattern[i] != '*') 70 continue; 71 /* 72 * State i is active, and pattern[i] is '*', so we can 73 * epsilon-transition to i+1. 74 */ 75 states[i + 1] = 1; 76 } 77 } 78 79 /* 80 * Returns true if the given string matches the pattern (which may contain ? 81 * and * as wildcards), and zero if it does not match. Uses an NFA internally. 82 */ 83 int 84 match_pattern(const char *s, const char *pattern) 85 { 86 size_t M; 87 size_t i; 88 char *states, *next_states, *tmp; 89 int active, matched = 0; 90 91 /* trivial case: empty pattern vs empty input */ 92 if ((M = strlen(pattern)) == 0) 93 return *s == '\0'; 94 95 /* A state for each pattern character, plus one final accepting state */ 96 states = xcalloc(M + 1, sizeof(*states)); 97 next_states = xcalloc(M + 1, sizeof(*next_states)); 98 99 /* Initial state: state 0 is active */ 100 states[0] = 1; 101 /* Other states might be reachable now if the pattern starts with '*' */ 102 epsilon_closure(states, pattern, M); 103 104 for (; *s; s++) { 105 memset(next_states, 0, M + 1); 106 107 /* Calculate the reachable next states given the input char */ 108 for (i = 0; i < M; i++) { 109 if (!states[i]) 110 continue; 111 if (pattern[i] == '*') { 112 /* 113 * '*' matches any character, so we can 114 * stay in state i 115 */ 116 next_states[i] = 1; 117 } else if (pattern[i] == '?' || pattern[i] == *s) { 118 /* 119 * '?' matches any character, or we have 120 * a literal match. 121 */ 122 next_states[i + 1] = 1; 123 } 124 } 125 126 /* Expand the reachable next states with epsilon transitions */ 127 epsilon_closure(next_states, pattern, M); 128 129 /* Swap states and next_states */ 130 tmp = states; 131 states = next_states; 132 next_states = tmp; 133 134 /* Check if we have any active pattern states left */ 135 active = 0; 136 for (i = 0; i <= M; i++) { 137 if (states[i]) { 138 active = 1; 139 break; 140 } 141 } 142 if (!active) 143 goto out; /* No active states, fail early */ 144 } 145 /* 146 * We matched only if we ended up in the final, accepting state 147 * after consuming all the input. 148 */ 149 matched = states[M]; 150 out: 151 free(states); 152 free(next_states); 153 return matched; 154 } 155 156 /* 157 * Tries to match the string against the 158 * comma-separated sequence of subpatterns (each possibly preceded by ! to 159 * indicate negation). Returns -1 if negation matches, 1 if there is 160 * a positive match, 0 if there is no match at all. 161 */ 162 int 163 match_pattern_list(const char *string, const char *pattern, int dolower) 164 { 165 char sub[1024]; 166 int negated; 167 int got_positive; 168 u_int i, subi, len = strlen(pattern); 169 170 got_positive = 0; 171 for (i = 0; i < len;) { 172 /* Check if the subpattern is negated. */ 173 if (pattern[i] == '!') { 174 negated = 1; 175 i++; 176 } else 177 negated = 0; 178 179 /* 180 * Extract the subpattern up to a comma or end. Convert the 181 * subpattern to lowercase. 182 */ 183 for (subi = 0; 184 i < len && subi < sizeof(sub) - 1 && pattern[i] != ','; 185 subi++, i++) 186 sub[subi] = dolower && isupper((u_char)pattern[i]) ? 187 tolower((u_char)pattern[i]) : pattern[i]; 188 /* If subpattern too long, return failure (no match). */ 189 if (subi >= sizeof(sub) - 1) 190 return 0; 191 192 /* If the subpattern was terminated by a comma, then skip it. */ 193 if (i < len && pattern[i] == ',') 194 i++; 195 196 /* Null-terminate the subpattern. */ 197 sub[subi] = '\0'; 198 199 /* Try to match the subpattern against the string. */ 200 if (match_pattern(string, sub)) { 201 if (negated) 202 return -1; /* Negative */ 203 else 204 got_positive = 1; /* Positive */ 205 } 206 } 207 208 /* 209 * Return success if got a positive match. If there was a negative 210 * match, we have already returned -1 and never get here. 211 */ 212 return got_positive; 213 } 214 215 /* Match a list representing users or groups. */ 216 int 217 match_usergroup_pattern_list(const char *string, const char *pattern) 218 { 219 /* Case sensitive match */ 220 return match_pattern_list(string, pattern, 0); 221 } 222 223 /* 224 * Tries to match the host name (which must be in all lowercase) against the 225 * comma-separated sequence of subpatterns (each possibly preceded by ! to 226 * indicate negation). Returns -1 if negation matches, 1 if there is 227 * a positive match, 0 if there is no match at all. 228 */ 229 int 230 match_hostname(const char *host, const char *pattern) 231 { 232 char *hostcopy = xstrdup(host); 233 int r; 234 235 lowercase(hostcopy); 236 r = match_pattern_list(hostcopy, pattern, 1); 237 free(hostcopy); 238 return r; 239 } 240 241 /* 242 * returns 0 if we get a negative match for the hostname or the ip 243 * or if we get no match at all. returns -1 on error, or 1 on 244 * successful match. 245 */ 246 int 247 match_host_and_ip(const char *host, const char *ipaddr, 248 const char *patterns) 249 { 250 int mhost, mip; 251 252 if ((mip = addr_match_list(ipaddr, patterns)) == -2) 253 return -1; /* error in ipaddr match */ 254 else if (host == NULL || ipaddr == NULL || mip == -1) 255 return 0; /* negative ip address match, or testing pattern */ 256 257 /* negative hostname match */ 258 if ((mhost = match_hostname(host, patterns)) == -1) 259 return 0; 260 /* no match at all */ 261 if (mhost == 0 && mip == 0) 262 return 0; 263 return 1; 264 } 265 266 /* 267 * Match user, user@host_or_ip, user@host_or_ip_list against pattern. 268 * If user, host and ipaddr are all NULL then validate pattern/ 269 * Returns -1 on invalid pattern, 0 on no match, 1 on match. 270 */ 271 int 272 match_user(const char *user, const char *host, const char *ipaddr, 273 const char *pattern) 274 { 275 char *p, *pat; 276 int ret; 277 278 /* test mode */ 279 if (user == NULL && host == NULL && ipaddr == NULL) { 280 if ((p = strrchr(pattern, '@')) != NULL && 281 match_host_and_ip(NULL, NULL, p + 1) < 0) 282 return -1; 283 return 0; 284 } 285 286 if (user == NULL) 287 return 0; /* shouldn't happen */ 288 289 if (strrchr(pattern, '@') == NULL) 290 return match_pattern(user, pattern); 291 292 pat = xstrdup(pattern); 293 p = strrchr(pat, '@'); 294 *p++ = '\0'; 295 296 if ((ret = match_pattern(user, pat)) == 1) 297 ret = match_host_and_ip(host, ipaddr, p); 298 free(pat); 299 300 return ret; 301 } 302 303 /* 304 * Returns first item from client-list that is also supported by server-list, 305 * caller must free the returned string. 306 */ 307 #define MAX_PROP 40 308 #define SEP "," 309 char * 310 match_list(const char *client, const char *server, u_int *next) 311 { 312 char *sproposals[MAX_PROP]; 313 char *c, *s, *p, *ret, *cp, *sp; 314 int i, j, nproposals; 315 316 c = cp = xstrdup(client); 317 s = sp = xstrdup(server); 318 319 for ((p = strsep(&sp, SEP)), i=0; p && *p != '\0'; 320 (p = strsep(&sp, SEP)), i++) { 321 if (i < MAX_PROP) 322 sproposals[i] = p; 323 else 324 break; 325 } 326 nproposals = i; 327 328 for ((p = strsep(&cp, SEP)), i=0; p && *p != '\0'; 329 (p = strsep(&cp, SEP)), i++) { 330 for (j = 0; j < nproposals; j++) { 331 if (strcmp(p, sproposals[j]) == 0) { 332 ret = xstrdup(p); 333 if (next != NULL) 334 *next = (cp == NULL) ? 335 strlen(c) : (u_int)(cp - c); 336 free(c); 337 free(s); 338 return ret; 339 } 340 } 341 } 342 if (next != NULL) 343 *next = strlen(c); 344 free(c); 345 free(s); 346 return NULL; 347 } 348 349 /* 350 * Filter proposal using pattern-list filter. 351 * "denylist" determines sense of filter: 352 * non-zero indicates that items matching filter should be excluded. 353 * zero indicates that only items matching filter should be included. 354 * returns NULL on allocation error, otherwise caller must free result. 355 */ 356 static char * 357 filter_list(const char *proposal, const char *filter, int denylist) 358 { 359 size_t len = strlen(proposal) + 1; 360 char *fix_prop = malloc(len); 361 char *orig_prop = strdup(proposal); 362 char *cp, *tmp; 363 int r; 364 365 if (fix_prop == NULL || orig_prop == NULL) { 366 free(orig_prop); 367 free(fix_prop); 368 return NULL; 369 } 370 371 tmp = orig_prop; 372 *fix_prop = '\0'; 373 while ((cp = strsep(&tmp, ",")) != NULL) { 374 r = match_pattern_list(cp, filter, 0); 375 if ((denylist && r != 1) || (!denylist && r == 1)) { 376 if (*fix_prop != '\0') 377 strlcat(fix_prop, ",", len); 378 strlcat(fix_prop, cp, len); 379 } 380 } 381 free(orig_prop); 382 return fix_prop; 383 } 384 385 /* 386 * Filters a comma-separated list of strings, excluding any entry matching 387 * the 'filter' pattern list. Caller must free returned string. 388 */ 389 char * 390 match_filter_denylist(const char *proposal, const char *filter) 391 { 392 return filter_list(proposal, filter, 1); 393 } 394 395 /* 396 * Filters a comma-separated list of strings, including only entries matching 397 * the 'filter' pattern list. Caller must free returned string. 398 */ 399 char * 400 match_filter_allowlist(const char *proposal, const char *filter) 401 { 402 return filter_list(proposal, filter, 0); 403 } 404
Indexes created Wed Sep 23 00:26:21 UTC 2026