1 /* $OpenBSD: match.c,v 1.39 2019/03/06 22:14:23 dtucker 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 <stdio.h> 44 45 #include "xmalloc.h" 46 #include "match.h" 47 #include "misc.h" 48 49 /* 50 * Returns true if the given string matches the pattern (which may contain ? 51 * and * as wildcards), and zero if it does not match. 52 */ 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 the asterisk. */ 64 pattern++; 65 66 /* If at end of pattern, accept immediately. */ 67 if (!*pattern) 68 return 1; 69 70 /* If next character in pattern is known, optimize. */ 71 if (*pattern != '?' && *pattern != '*') { 72 /* 73 * Look instances of the next character in 74 * pattern, and try to match starting from 75 * those. 76 */ 77 for (; *s; s++) 78 if (*s == *pattern && 79 match_pattern(s + 1, pattern + 1)) 80 return 1; 81 /* Failed. */ 82 return 0; 83 } 84 /* 85 * Move ahead one character at a time and try to 86 * match at each position. 87 */ 88 for (; *s; s++) 89 if (match_pattern(s, pattern)) 90 return 1; 91 /* Failed. */ 92 return 0; 93 } 94 /* 95 * There must be at least one more character in the string. 96 * If we are at the end, fail. 97 */ 98 if (!*s) 99 return 0; 100 101 /* Check if the next character of the string is acceptable. */ 102 if (*pattern != '?' && *pattern != *s) 103 return 0; 104 105 /* Move to the next character, both in string and in pattern. */ 106 s++; 107 pattern++; 108 } 109 /* NOTREACHED */ 110 } 111 112 /* 113 * Tries to match the string against the 114 * comma-separated sequence of subpatterns (each possibly preceded by ! to 115 * indicate negation). Returns -1 if negation matches, 1 if there is 116 * a positive match, 0 if there is no match at all. 117 */ 118 int 119 match_pattern_list(const char *string, const char *pattern, int dolower) 120 { 121 char sub[1024]; 122 int negated; 123 int got_positive; 124 u_int i, subi, len = strlen(pattern); 125 126 got_positive = 0; 127 for (i = 0; i < len;) { 128 /* Check if the subpattern is negated. */ 129 if (pattern[i] == '!') { 130 negated = 1; 131 i++; 132 } else 133 negated = 0; 134 135 /* 136 * Extract the subpattern up to a comma or end. Convert the 137 * subpattern to lowercase. 138 */ 139 for (subi = 0; 140 i < len && subi < sizeof(sub) - 1 && pattern[i] != ','; 141 subi++, i++) 142 sub[subi] = dolower && isupper((u_char)pattern[i]) ? 143 tolower((u_char)pattern[i]) : pattern[i]; 144 /* If subpattern too long, return failure (no match). */ 145 if (subi >= sizeof(sub) - 1) 146 return 0; 147 148 /* If the subpattern was terminated by a comma, then skip it. */ 149 if (i < len && pattern[i] == ',') 150 i++; 151 152 /* Null-terminate the subpattern. */ 153 sub[subi] = '\0'; 154 155 /* Try to match the subpattern against the string. */ 156 if (match_pattern(string, sub)) { 157 if (negated) 158 return -1; /* Negative */ 159 else 160 got_positive = 1; /* Positive */ 161 } 162 } 163 164 /* 165 * Return success if got a positive match. If there was a negative 166 * match, we have already returned -1 and never get here. 167 */ 168 return got_positive; 169 } 170 171 /* Match a list representing users or groups. */ 172 int 173 match_usergroup_pattern_list(const char *string, const char *pattern) 174 { 175 /* Case sensitive match */ 176 return match_pattern_list(string, pattern, 0); 177 } 178 179 /* 180 * Tries to match the host name (which must be in all lowercase) against the 181 * comma-separated sequence of subpatterns (each possibly preceded by ! to 182 * indicate negation). Returns -1 if negation matches, 1 if there is 183 * a positive match, 0 if there is no match at all. 184 */ 185 int 186 match_hostname(const char *host, const char *pattern) 187 { 188 char *hostcopy = xstrdup(host); 189 int r; 190 191 lowercase(hostcopy); 192 r = match_pattern_list(hostcopy, pattern, 1); 193 free(hostcopy); 194 return r; 195 } 196 197 /* 198 * returns 0 if we get a negative match for the hostname or the ip 199 * or if we get no match at all. returns -1 on error, or 1 on 200 * successful match. 201 */ 202 int 203 match_host_and_ip(const char *host, const char *ipaddr, 204 const char *patterns) 205 { 206 int mhost, mip; 207 208 if ((mip = addr_match_list(ipaddr, patterns)) == -2) 209 return -1; /* error in ipaddr match */ 210 else if (host == NULL || ipaddr == NULL || mip == -1) 211 return 0; /* negative ip address match, or testing pattern */ 212 213 /* negative hostname match */ 214 if ((mhost = match_hostname(host, patterns)) == -1) 215 return 0; 216 /* no match at all */ 217 if (mhost == 0 && mip == 0) 218 return 0; 219 return 1; 220 } 221 222 /* 223 * Match user, user@host_or_ip, user@host_or_ip_list against pattern. 224 * If user, host and ipaddr are all NULL then validate pattern/ 225 * Returns -1 on invalid pattern, 0 on no match, 1 on match. 226 */ 227 int 228 match_user(const char *user, const char *host, const char *ipaddr, 229 const char *pattern) 230 { 231 char *p, *pat; 232 int ret; 233 234 /* test mode */ 235 if (user == NULL && host == NULL && ipaddr == NULL) { 236 if ((p = strchr(pattern, '@')) != NULL && 237 match_host_and_ip(NULL, NULL, p + 1) < 0) 238 return -1; 239 return 0; 240 } 241 242 if ((p = strchr(pattern,'@')) == NULL) 243 return match_pattern(user, pattern); 244 245 pat = xstrdup(pattern); 246 p = strchr(pat, '@'); 247 *p++ = '\0'; 248 249 if ((ret = match_pattern(user, pat)) == 1) 250 ret = match_host_and_ip(host, ipaddr, p); 251 free(pat); 252 253 return ret; 254 } 255 256 /* 257 * Returns first item from client-list that is also supported by server-list, 258 * caller must free the returned string. 259 */ 260 #define MAX_PROP 40 261 #define SEP "," 262 char * 263 match_list(const char *client, const char *server, u_int *next) 264 { 265 char *sproposals[MAX_PROP]; 266 char *c, *s, *p, *ret, *cp, *sp; 267 int i, j, nproposals; 268 269 c = cp = xstrdup(client); 270 s = sp = xstrdup(server); 271 272 for ((p = strsep(&sp, SEP)), i=0; p && *p != '\0'; 273 (p = strsep(&sp, SEP)), i++) { 274 if (i < MAX_PROP) 275 sproposals[i] = p; 276 else 277 break; 278 } 279 nproposals = i; 280 281 for ((p = strsep(&cp, SEP)), i=0; p && *p != '\0'; 282 (p = strsep(&cp, SEP)), i++) { 283 for (j = 0; j < nproposals; j++) { 284 if (strcmp(p, sproposals[j]) == 0) { 285 ret = xstrdup(p); 286 if (next != NULL) 287 *next = (cp == NULL) ? 288 strlen(c) : (u_int)(cp - c); 289 free(c); 290 free(s); 291 return ret; 292 } 293 } 294 } 295 if (next != NULL) 296 *next = strlen(c); 297 free(c); 298 free(s); 299 return NULL; 300 } 301 302 /* 303 * Filter proposal using pattern-list filter. 304 * "blacklist" determines sense of filter: 305 * non-zero indicates that items matching filter should be excluded. 306 * zero indicates that only items matching filter should be included. 307 * returns NULL on allocation error, otherwise caller must free result. 308 */ 309 static char * 310 filter_list(const char *proposal, const char *filter, int blacklist) 311 { 312 size_t len = strlen(proposal) + 1; 313 char *fix_prop = malloc(len); 314 char *orig_prop = strdup(proposal); 315 char *cp, *tmp; 316 int r; 317 318 if (fix_prop == NULL || orig_prop == NULL) { 319 free(orig_prop); 320 free(fix_prop); 321 return NULL; 322 } 323 324 tmp = orig_prop; 325 *fix_prop = '\0'; 326 while ((cp = strsep(&tmp, ",")) != NULL) { 327 r = match_pattern_list(cp, filter, 0); 328 if ((blacklist && r != 1) || (!blacklist && r == 1)) { 329 if (*fix_prop != '\0') 330 strlcat(fix_prop, ",", len); 331 strlcat(fix_prop, cp, len); 332 } 333 } 334 free(orig_prop); 335 return fix_prop; 336 } 337 338 /* 339 * Filters a comma-separated list of strings, excluding any entry matching 340 * the 'filter' pattern list. Caller must free returned string. 341 */ 342 char * 343 match_filter_blacklist(const char *proposal, const char *filter) 344 { 345 return filter_list(proposal, filter, 1); 346 } 347 348 /* 349 * Filters a comma-separated list of strings, including only entries matching 350 * the 'filter' pattern list. Caller must free returned string. 351 */ 352 char * 353 match_filter_whitelist(const char *proposal, const char *filter) 354 { 355 return filter_list(proposal, filter, 0); 356 } 357