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 <sys/types.h> 39 40 #include <ctype.h> 41 #include <stdlib.h> 42 #include <string.h> 43 #include <stdarg.h> 44 #include <stdio.h> 45 46 #include "xmalloc.h" 47 #include "match.h" 48 #include "misc.h" 49 50 /* 51 * Returns true if the given string matches the pattern (which may contain ? 52 * and * as wildcards), and zero if it does not match. 53 */ 54 int 55 match_pattern(const char *s, const char *pattern) 56 { 57 for (;;) { 58 /* If at end of pattern, accept if also at end of string. */ 59 if (!*pattern) 60 return !*s; 61 62 if (*pattern == '*') { 63 /* Skip this and any consecutive asterisks. */ 64 while (*pattern == '*') 65 pattern++; 66 67 /* If at end of pattern, accept immediately. */ 68 if (!*pattern) 69 return 1; 70 71 /* If next character in pattern is known, optimize. */ 72 if (*pattern != '?' && *pattern != '*') { 73 /* 74 * Look instances of the next character in 75 * pattern, and try to match starting from 76 * those. 77 */ 78 for (; *s; s++) 79 if (*s == *pattern && 80 match_pattern(s + 1, pattern + 1)) 81 return 1; 82 /* Failed. */ 83 return 0; 84 } 85 /* 86 * Move ahead one character at a time and try to 87 * match at each position. 88 */ 89 for (; *s; s++) 90 if (match_pattern(s, pattern)) 91 return 1; 92 /* Failed. */ 93 return 0; 94 } 95 /* 96 * There must be at least one more character in the string. 97 * If we are at the end, fail. 98 */ 99 if (!*s) 100 return 0; 101 102 /* Check if the next character of the string is acceptable. */ 103 if (*pattern != '?' && *pattern != *s) 104 return 0; 105 106 /* Move to the next character, both in string and in pattern. */ 107 s++; 108 pattern++; 109 } 110 /* NOTREACHED */ 111 } 112 113 /* 114 * Tries to match the string against the 115 * comma-separated sequence of subpatterns (each possibly preceded by ! to 116 * indicate negation). Returns -1 if negation matches, 1 if there is 117 * a positive match, 0 if there is no match at all. 118 */ 119 int 120 match_pattern_list(const char *string, const char *pattern, int dolower) 121 { 122 char sub[1024]; 123 int negated; 124 int got_positive; 125 u_int i, subi, len = strlen(pattern); 126 127 got_positive = 0; 128 for (i = 0; i < len;) { 129 /* Check if the subpattern is negated. */ 130 if (pattern[i] == '!') { 131 negated = 1; 132 i++; 133 } else 134 negated = 0; 135 136 /* 137 * Extract the subpattern up to a comma or end. Convert the 138 * subpattern to lowercase. 139 */ 140 for (subi = 0; 141 i < len && subi < sizeof(sub) - 1 && pattern[i] != ','; 142 subi++, i++) 143 sub[subi] = dolower && isupper((u_char)pattern[i]) ? 144 tolower((u_char)pattern[i]) : pattern[i]; 145 /* If subpattern too long, return failure (no match). */ 146 if (subi >= sizeof(sub) - 1) 147 return 0; 148 149 /* If the subpattern was terminated by a comma, then skip it. */ 150 if (i < len && pattern[i] == ',') 151 i++; 152 153 /* Null-terminate the subpattern. */ 154 sub[subi] = '\0'; 155 156 /* Try to match the subpattern against the string. */ 157 if (match_pattern(string, sub)) { 158 if (negated) 159 return -1; /* Negative */ 160 else 161 got_positive = 1; /* Positive */ 162 } 163 } 164 165 /* 166 * Return success if got a positive match. If there was a negative 167 * match, we have already returned -1 and never get here. 168 */ 169 return got_positive; 170 } 171 172 /* Match a list representing users or groups. */ 173 int 174 match_usergroup_pattern_list(const char *string, const char *pattern) 175 { 176 /* Case sensitive match */ 177 return match_pattern_list(string, pattern, 0); 178 } 179 180 /* 181 * Tries to match the host name (which must be in all lowercase) against the 182 * comma-separated sequence of subpatterns (each possibly preceded by ! to 183 * indicate negation). Returns -1 if negation matches, 1 if there is 184 * a positive match, 0 if there is no match at all. 185 */ 186 int 187 match_hostname(const char *host, const char *pattern) 188 { 189 char *hostcopy = xstrdup(host); 190 int r; 191 192 lowercase(hostcopy); 193 r = match_pattern_list(hostcopy, pattern, 1); 194 free(hostcopy); 195 return r; 196 } 197 198 /* 199 * returns 0 if we get a negative match for the hostname or the ip 200 * or if we get no match at all. returns -1 on error, or 1 on 201 * successful match. 202 */ 203 int 204 match_host_and_ip(const char *host, const char *ipaddr, 205 const char *patterns) 206 { 207 int mhost, mip; 208 209 if ((mip = addr_match_list(ipaddr, patterns)) == -2) 210 return -1; /* error in ipaddr match */ 211 else if (host == NULL || ipaddr == NULL || mip == -1) 212 return 0; /* negative ip address match, or testing pattern */ 213 214 /* negative hostname match */ 215 if ((mhost = match_hostname(host, patterns)) == -1) 216 return 0; 217 /* no match at all */ 218 if (mhost == 0 && mip == 0) 219 return 0; 220 return 1; 221 } 222 223 /* 224 * Match user, user@host_or_ip, user@host_or_ip_list against pattern. 225 * If user, host and ipaddr are all NULL then validate pattern/ 226 * Returns -1 on invalid pattern, 0 on no match, 1 on match. 227 */ 228 int 229 match_user(const char *user, const char *host, const char *ipaddr, 230 const char *pattern) 231 { 232 char *p, *pat; 233 int ret; 234 235 /* test mode */ 236 if (user == NULL && host == NULL && ipaddr == NULL) { 237 if ((p = strchr(pattern, '@')) != NULL && 238 match_host_and_ip(NULL, NULL, p + 1) < 0) 239 return -1; 240 return 0; 241 } 242 243 if (user == NULL) 244 return 0; /* shouldn't happen */ 245 246 if ((p = strchr(pattern, '@')) == NULL) 247 return match_pattern(user, pattern); 248 249 pat = xstrdup(pattern); 250 p = strchr(pat, '@'); 251 *p++ = '\0'; 252 253 if ((ret = match_pattern(user, pat)) == 1) 254 ret = match_host_and_ip(host, ipaddr, p); 255 free(pat); 256 257 return ret; 258 } 259 260 /* 261 * Returns first item from client-list that is also supported by server-list, 262 * caller must free the returned string. 263 */ 264 #define MAX_PROP 40 265 #define SEP "," 266 char * 267 match_list(const char *client, const char *server, u_int *next) 268 { 269 char *sproposals[MAX_PROP]; 270 char *c, *s, *p, *ret, *cp, *sp; 271 int i, j, nproposals; 272 273 c = cp = xstrdup(client); 274 s = sp = xstrdup(server); 275 276 for ((p = strsep(&sp, SEP)), i=0; p && *p != '\0'; 277 (p = strsep(&sp, SEP)), i++) { 278 if (i < MAX_PROP) 279 sproposals[i] = p; 280 else 281 break; 282 } 283 nproposals = i; 284 285 for ((p = strsep(&cp, SEP)), i=0; p && *p != '\0'; 286 (p = strsep(&cp, SEP)), i++) { 287 for (j = 0; j < nproposals; j++) { 288 if (strcmp(p, sproposals[j]) == 0) { 289 ret = xstrdup(p); 290 if (next != NULL) 291 *next = (cp == NULL) ? 292 strlen(c) : (u_int)(cp - c); 293 free(c); 294 free(s); 295 return ret; 296 } 297 } 298 } 299 if (next != NULL) 300 *next = strlen(c); 301 free(c); 302 free(s); 303 return NULL; 304 } 305 306 /* 307 * Filter proposal using pattern-list filter. 308 * "denylist" determines sense of filter: 309 * non-zero indicates that items matching filter should be excluded. 310 * zero indicates that only items matching filter should be included. 311 * returns NULL on allocation error, otherwise caller must free result. 312 */ 313 static char * 314 filter_list(const char *proposal, const char *filter, int denylist) 315 { 316 size_t len = strlen(proposal) + 1; 317 char *fix_prop = malloc(len); 318 char *orig_prop = strdup(proposal); 319 char *cp, *tmp; 320 int r; 321 322 if (fix_prop == NULL || orig_prop == NULL) { 323 free(orig_prop); 324 free(fix_prop); 325 return NULL; 326 } 327 328 tmp = orig_prop; 329 *fix_prop = '\0'; 330 while ((cp = strsep(&tmp, ",")) != NULL) { 331 r = match_pattern_list(cp, filter, 0); 332 if ((denylist && r != 1) || (!denylist && r == 1)) { 333 if (*fix_prop != '\0') 334 strlcat(fix_prop, ",", len); 335 strlcat(fix_prop, cp, len); 336 } 337 } 338 free(orig_prop); 339 return fix_prop; 340 } 341 342 /* 343 * Filters a comma-separated list of strings, excluding any entry matching 344 * the 'filter' pattern list. Caller must free returned string. 345 */ 346 char * 347 match_filter_denylist(const char *proposal, const char *filter) 348 { 349 return filter_list(proposal, filter, 1); 350 } 351 352 /* 353 * Filters a comma-separated list of strings, including only entries matching 354 * the 'filter' pattern list. Caller must free returned string. 355 */ 356 char * 357 match_filter_allowlist(const char *proposal, const char *filter) 358 { 359 return filter_list(proposal, filter, 0); 360 } 361