1 /* $OpenBSD: match.c,v 1.43 2020/11/03 22:53:12 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 ((p = strchr(pattern, '@')) == NULL) 251 return match_pattern(user, pattern); 252 253 pat = xstrdup(pattern); 254 p = strchr(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