access.c

   1 /*
   2  * Routines to authenticate access to a daemon (hosts allow/deny).
   3  *
   4  * Copyright (C) 1998 Andrew Tridgell
   5  * Copyright (C) 2004-2007 Wayne Davison
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 3 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License along
  18  * with this program; if not, visit the http://fsf.org website.
  19  */
  20
  21 #include "rsync.h"
  22
  23 static int match_hostname(char *host, char *tok)
  24 {
  25         if (!host || !*host)
  26                 return 0;
  27         return wildmatch(tok, host);
  28 }
  29
  30 static int match_binary(char *b1, char *b2, char *mask, int addrlen)
  31 {
  32         int i;
  33
  34         for (i = 0; i < addrlen; i++) {
  35                 if ((b1[i] ^ b2[i]) & mask[i])
  36                         return 0;
  37         }
  38
  39         return 1;
  40 }
  41
  42 static void make_mask(char *mask, int plen, int addrlen)
  43 {
  44         int w, b;
  45
  46         w = plen >> 3;
  47         b = plen & 0x7;
  48
  49         if (w)
  50                 memset(mask, 0xff, w);
  51         if (w < addrlen)
  52                 mask[w] = 0xff & (0xff<<(8-b));
  53         if (w+1 < addrlen)
  54                 memset(mask+w+1, 0, addrlen-w-1);
  55
  56         return;
  57 }
  58
  59 static int match_address(char *addr, char *tok)
  60 {
  61         char *p;
  62         struct addrinfo hints, *resa, *rest;
  63         int gai;
  64         int ret = 0;
  65         int addrlen = 0;
  66 #ifdef HAVE_STRTOL
  67         long int bits;
  68 #else
  69         int bits;
  70 #endif
  71         char mask[16];
  72         char *a = NULL, *t = NULL;
  73         unsigned int len;
  74
  75         if (!addr || !*addr)
  76                 return 0;
  77
  78         p = strchr(tok,'/');
  79         if (p) {
  80                 *p = '\0';
  81                 len = p - tok;
  82         } else
  83                 len = strlen(tok);
  84
  85         /* Fail quietly if tok is a hostname (not an address) */
  86         if (strspn(tok, ".0123456789") != len
  87 #ifdef INET6
  88             && strchr(tok, ':') == NULL
  89 #endif
  90         ) {
  91                 if (p)
  92                         *p = '/';
  93                 return 0;
  94         }
  95
  96         memset(&hints, 0, sizeof(hints));
  97         hints.ai_family = PF_UNSPEC;
  98         hints.ai_socktype = SOCK_STREAM;
  99 #ifdef AI_NUMERICHOST
 100         hints.ai_flags = AI_NUMERICHOST;
 101 #endif
 102
 103         if (getaddrinfo(addr, NULL, &hints, &resa) != 0) {
 104                 if (p)
 105                         *p = '/';
 106                 return 0;
 107         }
 108
 109         gai = getaddrinfo(tok, NULL, &hints, &rest);
 110         if (p)
 111                 *p++ = '/';
 112         if (gai != 0) {
 113                 rprintf(FLOG, "error matching address %s: %s\n",
 114                         tok, gai_strerror(gai));
 115                 freeaddrinfo(resa);
 116                 return 0;
 117         }
 118
 119         if (rest->ai_family != resa->ai_family) {
 120                 ret = 0;
 121                 goto out;
 122         }
 123
 124         switch(resa->ai_family) {
 125         case PF_INET:
 126                 a = (char *)&((struct sockaddr_in *)resa->ai_addr)->sin_addr;
 127                 t = (char *)&((struct sockaddr_in *)rest->ai_addr)->sin_addr;
 128                 addrlen = 4;
 129
 130                 break;
 131
 132 #ifdef INET6
 133         case PF_INET6:
 134             {
 135                 struct sockaddr_in6 *sin6a, *sin6t;
 136
 137                 sin6a = (struct sockaddr_in6 *)resa->ai_addr;
 138                 sin6t = (struct sockaddr_in6 *)rest->ai_addr;
 139
 140                 a = (char *)&sin6a->sin6_addr;
 141                 t = (char *)&sin6t->sin6_addr;
 142
 143                 addrlen = 16;
 144
 145 #ifdef HAVE_SOCKADDR_IN6_SCOPE_ID
 146                 if (sin6t->sin6_scope_id &&
 147                     sin6a->sin6_scope_id != sin6t->sin6_scope_id) {
 148                         ret = 0;
 149                         goto out;
 150                 }
 151 #endif
 152
 153                 break;
 154             }
 155 #endif
 156         default:
 157             rprintf(FLOG, "unknown family %u\n", rest->ai_family);
 158             ret = 0;
 159             goto out;
 160         }
 161
 162         bits = -1;
 163         if (p) {
 164                 if (inet_pton(resa->ai_addr->sa_family, p, mask) <= 0) {
 165 #ifdef HAVE_STRTOL
 166                         char *ep = NULL;
 167 #else
 168                         unsigned char *pp;
 169 #endif
 170
 171 #ifdef HAVE_STRTOL
 172                         bits = strtol(p, &ep, 10);
 173                         if (!*p || *ep) {
 174                                 rprintf(FLOG, "malformed mask in %s\n", tok);
 175                                 ret = 0;
 176                                 goto out;
 177                         }
 178 #else
 179                         for (pp = (unsigned char *)p; *pp; pp++) {
 180                                 if (!isascii(*pp) || !isdigit(*pp)) {
 181                                         rprintf(FLOG, "malformed mask in %s\n", tok);
 182                                         ret = 0;
 183                                         goto out;
 184                                 }
 185                         }
 186                         bits = atoi(p);
 187 #endif
 188                         if (bits == 0) {
 189                                 ret = 1;
 190                                 goto out;
 191                         }
 192                         if (bits < 0 || bits > (addrlen << 3)) {
 193                                 rprintf(FLOG, "malformed mask in %s\n", tok);
 194                                 ret = 0;
 195                                 goto out;
 196                         }
 197                 }
 198         } else {
 199                 bits = 128;
 200         }
 201
 202         if (bits >= 0)
 203                 make_mask(mask, bits, addrlen);
 204
 205         ret = match_binary(a, t, mask, addrlen);
 206
 207   out:
 208         freeaddrinfo(resa);
 209         freeaddrinfo(rest);
 210         return ret;
 211 }
 212
 213 static int access_match(char *list, char *addr, char *host)
 214 {
 215         char *tok;
 216         char *list2 = strdup(list);
 217
 218         if (!list2)
 219                 out_of_memory("access_match");
 220
 221         strlower(list2);
 222         if (host)
 223                 strlower(host);
 224
 225         for (tok = strtok(list2, " ,\t"); tok; tok = strtok(NULL, " ,\t")) {
 226                 if (match_hostname(host, tok) || match_address(addr, tok)) {
 227                         free(list2);
 228                         return 1;
 229                 }
 230         }
 231
 232         free(list2);
 233         return 0;
 234 }
 235
 236 int allow_access(char *addr, char *host, char *allow_list, char *deny_list)
 237 {
 238         if (allow_list && !*allow_list)
 239                 allow_list = NULL;
 240         if (deny_list && !*deny_list)
 241                 deny_list = NULL;
 242
 243         /* If we match an allow-list item, we always allow access. */
 244         if (allow_list) {
 245                 if (access_match(allow_list, addr, host))
 246                         return 1;
 247                 /* For an allow-list w/o a deny-list, disallow non-matches. */
 248                 if (!deny_list)
 249                         return 0;
 250         }
 251
 252         /* If we match a deny-list item (and got past any allow-list
 253          * items), we always disallow access. */
 254         if (deny_list && access_match(deny_list, addr, host))
 255                 return 0;
 256
 257         /* Allow all other access. */
 258         return 1;
 259 }