1 /* $OpenBSD: match.c,v 1.42 2020/07/05 23:59:45 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 55 int 56 match_pattern(const char *s, const char *pattern) 57 { 58 for (;;) { 59 /* If at end of pattern, accept if also at end of string. */ 60 if (!*pattern) 61 return !*s; 62 63 if (*pattern == '*') { 64 /* Skip the asterisk. */ 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 ((p = strchr(pattern, '@')) == NULL) 244 return match_pattern(user, pattern); 245 246 pat = xstrdup(pattern); 247 p = strchr(pat, '@'); 248 *p++ = '\0'; 249 250 if ((ret = match_pattern(user, pat)) == 1) 251 ret = match_host_and_ip(host, ipaddr, p); 252 free(pat); 253 254 return ret; 255 } 256 257 /* 258 * Returns first item from client-list that is also supported by server-list, 259 * caller must free the returned string. 260 */ 261 #define MAX_PROP 40 262 #define SEP "," 263 char * 264 match_list(const char *client, const char *server, u_int *next) 265 { 266 char *sproposals[MAX_PROP]; 267 char *c, *s, *p, *ret, *cp, *sp; 268 int i, j, nproposals; 269 270 c = cp = xstrdup(client); 271 s = sp = xstrdup(server); 272 273 for ((p = strsep(&sp, SEP)), i=0; p && *p != '\0'; 274 (p = strsep(&sp, SEP)), i++) { 275 if (i < MAX_PROP) 276 sproposals[i] = p; 277 else 278 break; 279 } 280 nproposals = i; 281 282 for ((p = strsep(&cp, SEP)), i=0; p && *p != '\0'; 283 (p = strsep(&cp, SEP)), i++) { 284 for (j = 0; j < nproposals; j++) { 285 if (strcmp(p, sproposals[j]) == 0) { 286 ret = xstrdup(p); 287 if (next != NULL) 288 *next = (cp == NULL) ? 289 strlen(c) : (u_int)(cp - c); 290 free(c); 291 free(s); 292 return ret; 293 } 294 } 295 } 296 if (next != NULL) 297 *next = strlen(c); 298 free(c); 299 free(s); 300 return NULL; 301 } 302 303 /* 304 * Filter proposal using pattern-list filter. 305 * "denylist" determines sense of filter: 306 * non-zero indicates that items matching filter should be excluded. 307 * zero indicates that only items matching filter should be included. 308 * returns NULL on allocation error, otherwise caller must free result. 309 */ 310 static char * 311 filter_list(const char *proposal, const char *filter, int denylist) 312 { 313 size_t len = strlen(proposal) + 1; 314 char *fix_prop = malloc(len); 315 char *orig_prop = strdup(proposal); 316 char *cp, *tmp; 317 int r; 318 319 if (fix_prop == NULL || orig_prop == NULL) { 320 free(orig_prop); 321 free(fix_prop); 322 return NULL; 323 } 324 325 tmp = orig_prop; 326 *fix_prop = '\0'; 327 while ((cp = strsep(&tmp, ",")) != NULL) { 328 r = match_pattern_list(cp, filter, 0); 329 if ((denylist && r != 1) || (!denylist && r == 1)) { 330 if (*fix_prop != '\0') 331 strlcat(fix_prop, ",", len); 332 strlcat(fix_prop, cp, len); 333 } 334 } 335 free(orig_prop); 336 return fix_prop; 337 } 338 339 /* 340 * Filters a comma-separated list of strings, excluding any entry matching 341 * the 'filter' pattern list. Caller must free returned string. 342 */ 343 char * 344 match_filter_denylist(const char *proposal, const char *filter) 345 { 346 return filter_list(proposal, filter, 1); 347 } 348 349 /* 350 * Filters a comma-separated list of strings, including only entries matching 351 * the 'filter' pattern list. Caller must free returned string. 352 */ 353 char * 354 match_filter_allowlist(const char *proposal, const char *filter) 355 { 356 return filter_list(proposal, filter, 0); 357 } 358