1 /* $NetBSD: match.c,v 1.17 2024/09/24 21:32:18 christos Exp $ */ 2 /* $OpenBSD: match.c,v 1.45 2024/09/06 02:30:44 djm Exp $ */ 3 4 /* 5 * Author: Tatu Ylonen <ylo@cs.hut.fi> 6 * Copyright (c) 1995 Tatu Ylonen <ylo@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 * 19 * Redistribution and use in source and binary forms, with or without 20 * modification, are permitted provided that the following conditions 21 * are met: 22 * 1. Redistributions of source code must retain the above copyright 23 * notice, this list of conditions and the following disclaimer. 24 * 2. Redistributions in binary form must reproduce the above copyright 25 * notice, this list of conditions and the following disclaimer in the 26 * documentation and/or other materials provided with the distribution. 27 * 28 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 29 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 30 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 31 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 33 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 34 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 35 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 36 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 37 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 38 */ 39 40 #include "includes.h" 41 __RCSID("$NetBSD: match.c,v 1.17 2024/09/24 21:32:18 christos Exp $"); 42 #include <sys/types.h> 43 44 #include <ctype.h> 45 #include <stdlib.h> 46 #include <string.h> 47 #include <stdarg.h> 48 #include <stdio.h> 49 50 #include "xmalloc.h" 51 #include "match.h" 52 #include "misc.h" 53 54 /* 55 * Returns true if the given string matches the pattern (which may contain ? 56 * and * as wildcards), and zero if it does not match. 57 */ 58 int 59 match_pattern(const char *s, const char *pattern) 60 { 61 for (;;) { 62 /* If at end of pattern, accept if also at end of string. */ 63 if (!*pattern) 64 return !*s; 65 66 if (*pattern == '*') { 67 /* Skip this and any consecutive asterisks. */ 68 while (*pattern == '*') 69 pattern++; 70 71 /* If at end of pattern, accept immediately. */ 72 if (!*pattern) 73 return 1; 74 75 /* If next character in pattern is known, optimize. */ 76 if (*pattern != '?' && *pattern != '*') { 77 /* 78 * Look instances of the next character in 79 * pattern, and try to match starting from 80 * those. 81 */ 82 for (; *s; s++) 83 if (*s == *pattern && 84 match_pattern(s + 1, pattern + 1)) 85 return 1; 86 /* Failed. */ 87 return 0; 88 } 89 /* 90 * Move ahead one character at a time and try to 91 * match at each position. 92 */ 93 for (; *s; s++) 94 if (match_pattern(s, pattern)) 95 return 1; 96 /* Failed. */ 97 return 0; 98 } 99 /* 100 * There must be at least one more character in the string. 101 * If we are at the end, fail. 102 */ 103 if (!*s) 104 return 0; 105 106 /* Check if the next character of the string is acceptable. */ 107 if (*pattern != '?' && *pattern != *s) 108 return 0; 109 110 /* Move to the next character, both in string and in pattern. */ 111 s++; 112 pattern++; 113 } 114 /* NOTREACHED */ 115 } 116 117 /* 118 * Tries to match the string against the 119 * comma-separated sequence of subpatterns (each possibly preceded by ! to 120 * indicate negation). Returns -1 if negation matches, 1 if there is 121 * a positive match, 0 if there is no match at all. 122 */ 123 int 124 match_pattern_list(const char *string, const char *pattern, int dolower) 125 { 126 char sub[1024]; 127 int negated; 128 int got_positive; 129 u_int i, subi, len = strlen(pattern); 130 131 got_positive = 0; 132 for (i = 0; i < len;) { 133 /* Check if the subpattern is negated. */ 134 if (pattern[i] == '!') { 135 negated = 1; 136 i++; 137 } else 138 negated = 0; 139 140 /* 141 * Extract the subpattern up to a comma or end. Convert the 142 * subpattern to lowercase. 143 */ 144 for (subi = 0; 145 i < len && subi < sizeof(sub) - 1 && pattern[i] != ','; 146 subi++, i++) 147 sub[subi] = dolower && isupper((u_char)pattern[i]) ? 148 tolower((u_char)pattern[i]) : pattern[i]; 149 /* If subpattern too long, return failure (no match). */ 150 if (subi >= sizeof(sub) - 1) 151 return 0; 152 153 /* If the subpattern was terminated by a comma, then skip it. */ 154 if (i < len && pattern[i] == ',') 155 i++; 156 157 /* Null-terminate the subpattern. */ 158 sub[subi] = '\0'; 159 160 /* Try to match the subpattern against the string. */ 161 if (match_pattern(string, sub)) { 162 if (negated) 163 return -1; /* Negative */ 164 else 165 got_positive = 1; /* Positive */ 166 } 167 } 168 169 /* 170 * Return success if got a positive match. If there was a negative 171 * match, we have already returned -1 and never get here. 172 */ 173 return got_positive; 174 } 175 176 /* Match a list representing users or groups. */ 177 int 178 match_usergroup_pattern_list(const char *string, const char *pattern) 179 { 180 /* Case sensitive match */ 181 return match_pattern_list(string, pattern, 0); 182 } 183 184 /* 185 * Tries to match the host name (which must be in all lowercase) against the 186 * comma-separated sequence of subpatterns (each possibly preceded by ! to 187 * indicate negation). Returns -1 if negation matches, 1 if there is 188 * a positive match, 0 if there is no match at all. 189 */ 190 int 191 match_hostname(const char *host, const char *pattern) 192 { 193 char *hostcopy = xstrdup(host); 194 int r; 195 196 lowercase(hostcopy); 197 r = match_pattern_list(hostcopy, pattern, 1); 198 free(hostcopy); 199 return r; 200 } 201 202 /* 203 * returns 0 if we get a negative match for the hostname or the ip 204 * or if we get no match at all. returns -1 on error, or 1 on 205 * successful match. 206 */ 207 int 208 match_host_and_ip(const char *host, const char *ipaddr, 209 const char *patterns) 210 { 211 int mhost, mip; 212 213 if ((mip = addr_match_list(ipaddr, patterns)) == -2) 214 return -1; /* error in ipaddr match */ 215 else if (host == NULL || ipaddr == NULL || mip == -1) 216 return 0; /* negative ip address match, or testing pattern */ 217 218 /* negative hostname match */ 219 if ((mhost = match_hostname(host, patterns)) == -1) 220 return 0; 221 /* no match at all */ 222 if (mhost == 0 && mip == 0) 223 return 0; 224 return 1; 225 } 226 227 /* 228 * Match user, user@host_or_ip, user@host_or_ip_list against pattern. 229 * If user, host and ipaddr are all NULL then validate pattern/ 230 * Returns -1 on invalid pattern, 0 on no match, 1 on match. 231 */ 232 int 233 match_user(const char *user, const char *host, const char *ipaddr, 234 const char *pattern) 235 { 236 char *p, *pat; 237 int ret; 238 239 /* test mode */ 240 if (user == NULL && host == NULL && ipaddr == NULL) { 241 if ((p = strrchr(pattern, '@')) != NULL && 242 match_host_and_ip(NULL, NULL, p + 1) < 0) 243 return -1; 244 return 0; 245 } 246 247 if (user == NULL) 248 return 0; /* shouldn't happen */ 249 250 if (strrchr(pattern, '@') == NULL) 251 return match_pattern(user, pattern); 252 253 pat = xstrdup(pattern); 254 p = strrchr(pat, '@'); 255 *p++ = '\0'; 256 257 if ((ret = match_pattern(user, pat)) == 1) 258 ret = match_host_and_ip(host, ipaddr, p); 259 free(pat); 260 261 return ret; 262 } 263 264 /* 265 * Returns first item from client-list that is also supported by server-list, 266 * caller must free the returned string. 267 */ 268 #define MAX_PROP 40 269 #define SEP "," 270 char * 271 match_list(const char *client, const char *server, u_int *next) 272 { 273 char *sproposals[MAX_PROP]; 274 char *c, *s, *p, *ret, *cp, *sp; 275 int i, j, nproposals; 276 277 c = cp = xstrdup(client); 278 s = sp = xstrdup(server); 279 280 for ((p = strsep(&sp, SEP)), i=0; p && *p != '\0'; 281 (p = strsep(&sp, SEP)), i++) { 282 if (i < MAX_PROP) 283 sproposals[i] = p; 284 else 285 break; 286 } 287 nproposals = i; 288 289 for ((p = strsep(&cp, SEP)), i=0; p && *p != '\0'; 290 (p = strsep(&cp, SEP)), i++) { 291 for (j = 0; j < nproposals; j++) { 292 if (strcmp(p, sproposals[j]) == 0) { 293 ret = xstrdup(p); 294 if (next != NULL) 295 *next = (cp == NULL) ? 296 strlen(c) : (u_int)(cp - c); 297 free(c); 298 free(s); 299 return ret; 300 } 301 } 302 } 303 if (next != NULL) 304 *next = strlen(c); 305 free(c); 306 free(s); 307 return NULL; 308 } 309 310 /* 311 * Filter proposal using pattern-list filter. 312 * "denylist" determines sense of filter: 313 * non-zero indicates that items matching filter should be excluded. 314 * zero indicates that only items matching filter should be included. 315 * returns NULL on allocation error, otherwise caller must free result. 316 */ 317 static char * 318 filter_list(const char *proposal, const char *filter, int denylist) 319 { 320 size_t len = strlen(proposal) + 1; 321 char *fix_prop = malloc(len); 322 char *orig_prop = strdup(proposal); 323 char *cp, *tmp; 324 int r; 325 326 if (fix_prop == NULL || orig_prop == NULL) { 327 free(orig_prop); 328 free(fix_prop); 329 return NULL; 330 } 331 332 tmp = orig_prop; 333 *fix_prop = '\0'; 334 while ((cp = strsep(&tmp, ",")) != NULL) { 335 r = match_pattern_list(cp, filter, 0); 336 if ((denylist && r != 1) || (!denylist && r == 1)) { 337 if (*fix_prop != '\0') 338 strlcat(fix_prop, ",", len); 339 strlcat(fix_prop, cp, len); 340 } 341 } 342 free(orig_prop); 343 return fix_prop; 344 } 345 346 /* 347 * Filters a comma-separated list of strings, excluding any entry matching 348 * the 'filter' pattern list. Caller must free returned string. 349 */ 350 char * 351 match_filter_denylist(const char *proposal, const char *filter) 352 { 353 return filter_list(proposal, filter, 1); 354 } 355 356 /* 357 * Filters a comma-separated list of strings, including only entries matching 358 * the 'filter' pattern list. Caller must free returned string. 359 */ 360 char * 361 match_filter_allowlist(const char *proposal, const char *filter) 362 { 363 return filter_list(proposal, filter, 0); 364 } 365