crypto/openssh/match.c

   1 /* $OpenBSD: match.c,v 1.37 2017/03/10 04:24:55 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 <stdio.h>
  46
  47 #include "xmalloc.h"
  48 #include "match.h"
  49 #include "misc.h"
  50
  51 /*
  52  * Returns true if the given string matches the pattern (which may contain ?
  53  * and * as wildcards), and zero if it does not match.
  54  */
  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 the asterisk. */
  66                         pattern++;
  67
  68                         /* If at end of pattern, accept immediately. */
  69                         if (!*pattern)
  70                                 return 1;
  71
  72                         /* If next character in pattern is known, optimize. */
  73                         if (*pattern != '?' && *pattern != '*') {
  74                                 /*
  75                                  * Look instances of the next character in
  76                                  * pattern, and try to match starting from
  77                                  * those.
  78                                  */
  79                                 for (; *s; s++)
  80                                         if (*s == *pattern &&
  81                                             match_pattern(s + 1, pattern + 1))
  82                                                 return 1;
  83                                 /* Failed. */
  84                                 return 0;
  85                         }
  86                         /*
  87                          * Move ahead one character at a time and try to
  88                          * match at each position.
  89                          */
  90                         for (; *s; s++)
  91                                 if (match_pattern(s, pattern))
  92                                         return 1;
  93                         /* Failed. */
  94                         return 0;
  95                 }
  96                 /*
  97                  * There must be at least one more character in the string.
  98                  * If we are at the end, fail.
  99                  */
 100                 if (!*s)
 101                         return 0;
 102
 103                 /* Check if the next character of the string is acceptable. */
 104                 if (*pattern != '?' && *pattern != *s)
 105                         return 0;
 106
 107                 /* Move to the next character, both in string and in pattern. */
 108                 s++;
 109                 pattern++;
 110         }
 111         /* NOTREACHED */
 112 }
 113
 114 /*
 115  * Tries to match the string against the
 116  * comma-separated sequence of subpatterns (each possibly preceded by ! to
 117  * indicate negation).  Returns -1 if negation matches, 1 if there is
 118  * a positive match, 0 if there is no match at all.
 119  */
 120 int
 121 match_pattern_list(const char *string, const char *pattern, int dolower)
 122 {
 123         char sub[1024];
 124         int negated;
 125         int got_positive;
 126         u_int i, subi, len = strlen(pattern);
 127
 128         got_positive = 0;
 129         for (i = 0; i < len;) {
 130                 /* Check if the subpattern is negated. */
 131                 if (pattern[i] == '!') {
 132                         negated = 1;
 133                         i++;
 134                 } else
 135                         negated = 0;
 136
 137                 /*
 138                  * Extract the subpattern up to a comma or end.  Convert the
 139                  * subpattern to lowercase.
 140                  */
 141                 for (subi = 0;
 142                     i < len && subi < sizeof(sub) - 1 && pattern[i] != ',';
 143                     subi++, i++)
 144                         sub[subi] = dolower && isupper((u_char)pattern[i]) ?
 145                             tolower((u_char)pattern[i]) : pattern[i];
 146                 /* If subpattern too long, return failure (no match). */
 147                 if (subi >= sizeof(sub) - 1)
 148                         return 0;
 149
 150                 /* If the subpattern was terminated by a comma, then skip it. */
 151                 if (i < len && pattern[i] == ',')
 152                         i++;
 153
 154                 /* Null-terminate the subpattern. */
 155                 sub[subi] = '\0';
 156
 157                 /* Try to match the subpattern against the string. */
 158                 if (match_pattern(string, sub)) {
 159                         if (negated)
 160                                 return -1;              /* Negative */
 161                         else
 162                                 got_positive = 1;       /* Positive */
 163                 }
 164         }
 165
 166         /*
 167          * Return success if got a positive match.  If there was a negative
 168          * match, we have already returned -1 and never get here.
 169          */
 170         return got_positive;
 171 }
 172
 173 /*
 174  * Tries to match the host name (which must be in all lowercase) against the
 175  * comma-separated sequence of subpatterns (each possibly preceded by ! to
 176  * indicate negation).  Returns -1 if negation matches, 1 if there is
 177  * a positive match, 0 if there is no match at all.
 178  */
 179 int
 180 match_hostname(const char *host, const char *pattern)
 181 {
 182         char *hostcopy = xstrdup(host);
 183         int r;
 184
 185         lowercase(hostcopy);
 186         r = match_pattern_list(hostcopy, pattern, 1);
 187         free(hostcopy);
 188         return r;
 189 }
 190
 191 /*
 192  * returns 0 if we get a negative match for the hostname or the ip
 193  * or if we get no match at all.  returns -1 on error, or 1 on
 194  * successful match.
 195  */
 196 int
 197 match_host_and_ip(const char *host, const char *ipaddr,
 198     const char *patterns)
 199 {
 200         int mhost, mip;
 201
 202         if ((mip = addr_match_list(ipaddr, patterns)) == -2)
 203                 return -1; /* error in ipaddr match */
 204         else if (host == NULL || ipaddr == NULL || mip == -1)
 205                 return 0; /* negative ip address match, or testing pattern */
 206
 207         /* negative hostname match */
 208         if ((mhost = match_hostname(host, patterns)) == -1)
 209                 return 0;
 210         /* no match at all */
 211         if (mhost == 0 && mip == 0)
 212                 return 0;
 213         return 1;
 214 }
 215
 216 /*
 217  * Match user, user@host_or_ip, user@host_or_ip_list against pattern.
 218  * If user, host and ipaddr are all NULL then validate pattern/
 219  * Returns -1 on invalid pattern, 0 on no match, 1 on match.
 220  */
 221 int
 222 match_user(const char *user, const char *host, const char *ipaddr,
 223     const char *pattern)
 224 {
 225         char *p, *pat;
 226         int ret;
 227
 228         /* test mode */
 229         if (user == NULL && host == NULL && ipaddr == NULL) {
 230                 if ((p = strchr(pattern, '@')) != NULL &&
 231                     match_host_and_ip(NULL, NULL, p + 1) < 0)
 232                         return -1;
 233                 return 0;
 234         }
 235
 236         if ((p = strchr(pattern,'@')) == NULL)
 237                 return match_pattern(user, pattern);
 238
 239         pat = xstrdup(pattern);
 240         p = strchr(pat, '@');
 241         *p++ = '\0';
 242
 243         if ((ret = match_pattern(user, pat)) == 1)
 244                 ret = match_host_and_ip(host, ipaddr, p);
 245         free(pat);
 246
 247         return ret;
 248 }
 249
 250 /*
 251  * Returns first item from client-list that is also supported by server-list,
 252  * caller must free the returned string.
 253  */
 254 #define MAX_PROP        40
 255 #define SEP     ","
 256 char *
 257 match_list(const char *client, const char *server, u_int *next)
 258 {
 259         char *sproposals[MAX_PROP];
 260         char *c, *s, *p, *ret, *cp, *sp;
 261         int i, j, nproposals;
 262
 263         c = cp = xstrdup(client);
 264         s = sp = xstrdup(server);
 265
 266         for ((p = strsep(&sp, SEP)), i=0; p && *p != '\0';
 267             (p = strsep(&sp, SEP)), i++) {
 268                 if (i < MAX_PROP)
 269                         sproposals[i] = p;
 270                 else
 271                         break;
 272         }
 273         nproposals = i;
 274
 275         for ((p = strsep(&cp, SEP)), i=0; p && *p != '\0';
 276             (p = strsep(&cp, SEP)), i++) {
 277                 for (j = 0; j < nproposals; j++) {
 278                         if (strcmp(p, sproposals[j]) == 0) {
 279                                 ret = xstrdup(p);
 280                                 if (next != NULL)
 281                                         *next = (cp == NULL) ?
 282                                             strlen(c) : (u_int)(cp - c);
 283                                 free(c);
 284                                 free(s);
 285                                 return ret;
 286                         }
 287                 }
 288         }
 289         if (next != NULL)
 290                 *next = strlen(c);
 291         free(c);
 292         free(s);
 293         return NULL;
 294 }
 295
 296 /*
 297  * Filters a comma-separated list of strings, excluding any entry matching
 298  * the 'filter' pattern list. Caller must free returned string.
 299  */
 300 char *
 301 match_filter_list(const char *proposal, const char *filter)
 302 {
 303         size_t len = strlen(proposal) + 1;
 304         char *fix_prop = malloc(len);
 305         char *orig_prop = strdup(proposal);
 306         char *cp, *tmp;
 307
 308         if (fix_prop == NULL || orig_prop == NULL) {
 309                 free(orig_prop);
 310                 free(fix_prop);
 311                 return NULL;
 312         }
 313
 314         tmp = orig_prop;
 315         *fix_prop = '\0';
 316         while ((cp = strsep(&tmp, ",")) != NULL) {
 317                 if (match_pattern_list(cp, filter, 0) != 1) {
 318                         if (*fix_prop != '\0')
 319                                 strlcat(fix_prop, ",", len);
 320                         strlcat(fix_prop, cp, len);
 321                 }
 322         }
 323         free(orig_prop);
 324         return fix_prop;
 325 }
 326