crypto/openssh/match.c

   1 /* $OpenBSD: match.c,v 1.29 2013/11/20 20:54:10 deraadt 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
  46 #include "xmalloc.h"
  47 #include "match.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
 119 int
 120 match_pattern_list(const char *string, const char *pattern, u_int len,
 121     int dolower)
 122 {
 123         char sub[1024];
 124         int negated;
 125         int got_positive;
 126         u_int i, subi;
 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, skip the comma. */
 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, u_int len)
 181 {
 182         return match_pattern_list(host, pattern, len, 1);
 183 }
 184
 185 /*
 186  * returns 0 if we get a negative match for the hostname or the ip
 187  * or if we get no match at all.  returns -1 on error, or 1 on
 188  * successful match.
 189  */
 190 int
 191 match_host_and_ip(const char *host, const char *ipaddr,
 192     const char *patterns)
 193 {
 194         int mhost, mip;
 195
 196         /* error in ipaddr match */
 197         if ((mip = addr_match_list(ipaddr, patterns)) == -2)
 198                 return -1;
 199         else if (mip == -1) /* negative ip address match */
 200                 return 0;
 201
 202         /* negative hostname match */
 203         if ((mhost = match_hostname(host, patterns, strlen(patterns))) == -1)
 204                 return 0;
 205         /* no match at all */
 206         if (mhost == 0 && mip == 0)
 207                 return 0;
 208         return 1;
 209 }
 210
 211 /*
 212  * match user, user@host_or_ip, user@host_or_ip_list against pattern
 213  */
 214 int
 215 match_user(const char *user, const char *host, const char *ipaddr,
 216     const char *pattern)
 217 {
 218         char *p, *pat;
 219         int ret;
 220
 221         if ((p = strchr(pattern,'@')) == NULL)
 222                 return match_pattern(user, pattern);
 223
 224         pat = xstrdup(pattern);
 225         p = strchr(pat, '@');
 226         *p++ = '\0';
 227
 228         if ((ret = match_pattern(user, pat)) == 1)
 229                 ret = match_host_and_ip(host, ipaddr, p);
 230         free(pat);
 231
 232         return ret;
 233 }
 234
 235 /*
 236  * Returns first item from client-list that is also supported by server-list,
 237  * caller must free the returned string.
 238  */
 239 #define MAX_PROP        40
 240 #define SEP     ","
 241 char *
 242 match_list(const char *client, const char *server, u_int *next)
 243 {
 244         char *sproposals[MAX_PROP];
 245         char *c, *s, *p, *ret, *cp, *sp;
 246         int i, j, nproposals;
 247
 248         c = cp = xstrdup(client);
 249         s = sp = xstrdup(server);
 250
 251         for ((p = strsep(&sp, SEP)), i=0; p && *p != '\0';
 252             (p = strsep(&sp, SEP)), i++) {
 253                 if (i < MAX_PROP)
 254                         sproposals[i] = p;
 255                 else
 256                         break;
 257         }
 258         nproposals = i;
 259
 260         for ((p = strsep(&cp, SEP)), i=0; p && *p != '\0';
 261             (p = strsep(&cp, SEP)), i++) {
 262                 for (j = 0; j < nproposals; j++) {
 263                         if (strcmp(p, sproposals[j]) == 0) {
 264                                 ret = xstrdup(p);
 265                                 if (next != NULL)
 266                                         *next = (cp == NULL) ?
 267                                             strlen(c) : (u_int)(cp - c);
 268                                 free(c);
 269                                 free(s);
 270                                 return ret;
 271                         }
 272                 }
 273         }
 274         if (next != NULL)
 275                 *next = strlen(c);
 276         free(c);
 277         free(s);
 278         return NULL;
 279 }