| 1 | /* |
| 2 | * Routines to authenticate access to a daemon (hosts allow/deny). |
| 3 | * |
| 4 | * Copyright (C) 1998 Andrew Tridgell |
| 5 | * Copyright (C) 2004-2009 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 allow_forward_dns; |
| 24 | |
| 25 | extern const char undetermined_hostname[]; |
| 26 | |
| 27 | static int match_hostname(const char **host_ptr, const char *addr, const char *tok) |
| 28 | { |
| 29 | struct hostent *hp; |
| 30 | unsigned int i; |
| 31 | const char *host = *host_ptr; |
| 32 | |
| 33 | if (!host || !*host) |
| 34 | return 0; |
| 35 | |
| 36 | /* First check if the reverse-DNS-determined hostname matches. */ |
| 37 | if (iwildmatch(tok, host)) |
| 38 | return 1; |
| 39 | |
| 40 | if (!allow_forward_dns) |
| 41 | return 0; |
| 42 | |
| 43 | /* Fail quietly if tok is an address or wildcarded entry, not a simple hostname. */ |
| 44 | if (!tok[strspn(tok, ".0123456789")] || tok[strcspn(tok, ":/*?[")]) |
| 45 | return 0; |
| 46 | |
| 47 | /* Now try forward-DNS on the token (config-specified hostname) and see if the IP matches. */ |
| 48 | if (!(hp = gethostbyname(tok))) |
| 49 | return 0; |
| 50 | |
| 51 | for (i = 0; hp->h_addr_list[i] != NULL; i++) { |
| 52 | if (strcmp(addr, inet_ntoa(*(struct in_addr*)(hp->h_addr_list[i]))) == 0) { |
| 53 | /* If reverse lookups are off, we'll use the conf-specified |
| 54 | * hostname in preference to UNDETERMINED. */ |
| 55 | if (host == undetermined_hostname) { |
| 56 | if (!(*host_ptr = strdup(tok))) |
| 57 | *host_ptr = undetermined_hostname; |
| 58 | } |
| 59 | return 1; |
| 60 | } |
| 61 | } |
| 62 | |
| 63 | return 0; |
| 64 | } |
| 65 | |
| 66 | static int match_binary(const char *b1, const char *b2, const char *mask, int addrlen) |
| 67 | { |
| 68 | int i; |
| 69 | |
| 70 | for (i = 0; i < addrlen; i++) { |
| 71 | if ((b1[i] ^ b2[i]) & mask[i]) |
| 72 | return 0; |
| 73 | } |
| 74 | |
| 75 | return 1; |
| 76 | } |
| 77 | |
| 78 | static void make_mask(char *mask, int plen, int addrlen) |
| 79 | { |
| 80 | int w, b; |
| 81 | |
| 82 | w = plen >> 3; |
| 83 | b = plen & 0x7; |
| 84 | |
| 85 | if (w) |
| 86 | memset(mask, 0xff, w); |
| 87 | if (w < addrlen) |
| 88 | mask[w] = 0xff & (0xff<<(8-b)); |
| 89 | if (w+1 < addrlen) |
| 90 | memset(mask+w+1, 0, addrlen-w-1); |
| 91 | |
| 92 | return; |
| 93 | } |
| 94 | |
| 95 | static int match_address(const char *addr, const char *tok) |
| 96 | { |
| 97 | char *p; |
| 98 | struct addrinfo hints, *resa, *rest; |
| 99 | int gai; |
| 100 | int ret = 0; |
| 101 | int addrlen = 0; |
| 102 | #ifdef HAVE_STRTOL |
| 103 | long int bits; |
| 104 | #else |
| 105 | int bits; |
| 106 | #endif |
| 107 | char mask[16]; |
| 108 | char *a = NULL, *t = NULL; |
| 109 | |
| 110 | if (!addr || !*addr) |
| 111 | return 0; |
| 112 | |
| 113 | p = strchr(tok,'/'); |
| 114 | if (p) |
| 115 | *p = '\0'; |
| 116 | |
| 117 | /* Fail quietly if tok is a hostname, not an address. */ |
| 118 | if (tok[strspn(tok, ".0123456789")] && strchr(tok, ':') == NULL) { |
| 119 | if (p) |
| 120 | *p = '/'; |
| 121 | return 0; |
| 122 | } |
| 123 | |
| 124 | memset(&hints, 0, sizeof(hints)); |
| 125 | hints.ai_family = PF_UNSPEC; |
| 126 | hints.ai_socktype = SOCK_STREAM; |
| 127 | #ifdef AI_NUMERICHOST |
| 128 | hints.ai_flags = AI_NUMERICHOST; |
| 129 | #endif |
| 130 | |
| 131 | if (getaddrinfo(addr, NULL, &hints, &resa) != 0) { |
| 132 | if (p) |
| 133 | *p = '/'; |
| 134 | return 0; |
| 135 | } |
| 136 | |
| 137 | gai = getaddrinfo(tok, NULL, &hints, &rest); |
| 138 | if (p) |
| 139 | *p++ = '/'; |
| 140 | if (gai != 0) { |
| 141 | rprintf(FLOG, "error matching address %s: %s\n", |
| 142 | tok, gai_strerror(gai)); |
| 143 | freeaddrinfo(resa); |
| 144 | return 0; |
| 145 | } |
| 146 | |
| 147 | if (rest->ai_family != resa->ai_family) { |
| 148 | ret = 0; |
| 149 | goto out; |
| 150 | } |
| 151 | |
| 152 | switch(resa->ai_family) { |
| 153 | case PF_INET: |
| 154 | a = (char *)&((struct sockaddr_in *)resa->ai_addr)->sin_addr; |
| 155 | t = (char *)&((struct sockaddr_in *)rest->ai_addr)->sin_addr; |
| 156 | addrlen = 4; |
| 157 | |
| 158 | break; |
| 159 | |
| 160 | #ifdef INET6 |
| 161 | case PF_INET6: |
| 162 | { |
| 163 | struct sockaddr_in6 *sin6a, *sin6t; |
| 164 | |
| 165 | sin6a = (struct sockaddr_in6 *)resa->ai_addr; |
| 166 | sin6t = (struct sockaddr_in6 *)rest->ai_addr; |
| 167 | |
| 168 | a = (char *)&sin6a->sin6_addr; |
| 169 | t = (char *)&sin6t->sin6_addr; |
| 170 | |
| 171 | addrlen = 16; |
| 172 | |
| 173 | #ifdef HAVE_SOCKADDR_IN6_SCOPE_ID |
| 174 | if (sin6t->sin6_scope_id && |
| 175 | sin6a->sin6_scope_id != sin6t->sin6_scope_id) { |
| 176 | ret = 0; |
| 177 | goto out; |
| 178 | } |
| 179 | #endif |
| 180 | |
| 181 | break; |
| 182 | } |
| 183 | #endif |
| 184 | default: |
| 185 | rprintf(FLOG, "unknown family %u\n", rest->ai_family); |
| 186 | ret = 0; |
| 187 | goto out; |
| 188 | } |
| 189 | |
| 190 | bits = -1; |
| 191 | if (p) { |
| 192 | if (inet_pton(resa->ai_addr->sa_family, p, mask) <= 0) { |
| 193 | #ifdef HAVE_STRTOL |
| 194 | char *ep = NULL; |
| 195 | #else |
| 196 | unsigned char *pp; |
| 197 | #endif |
| 198 | |
| 199 | #ifdef HAVE_STRTOL |
| 200 | bits = strtol(p, &ep, 10); |
| 201 | if (!*p || *ep) { |
| 202 | rprintf(FLOG, "malformed mask in %s\n", tok); |
| 203 | ret = 0; |
| 204 | goto out; |
| 205 | } |
| 206 | #else |
| 207 | for (pp = (unsigned char *)p; *pp; pp++) { |
| 208 | if (!isascii(*pp) || !isdigit(*pp)) { |
| 209 | rprintf(FLOG, "malformed mask in %s\n", tok); |
| 210 | ret = 0; |
| 211 | goto out; |
| 212 | } |
| 213 | } |
| 214 | bits = atoi(p); |
| 215 | #endif |
| 216 | if (bits == 0) { |
| 217 | ret = 1; |
| 218 | goto out; |
| 219 | } |
| 220 | if (bits < 0 || bits > (addrlen << 3)) { |
| 221 | rprintf(FLOG, "malformed mask in %s\n", tok); |
| 222 | ret = 0; |
| 223 | goto out; |
| 224 | } |
| 225 | } |
| 226 | } else { |
| 227 | bits = 128; |
| 228 | } |
| 229 | |
| 230 | if (bits >= 0) |
| 231 | make_mask(mask, bits, addrlen); |
| 232 | |
| 233 | ret = match_binary(a, t, mask, addrlen); |
| 234 | |
| 235 | out: |
| 236 | freeaddrinfo(resa); |
| 237 | freeaddrinfo(rest); |
| 238 | return ret; |
| 239 | } |
| 240 | |
| 241 | static int access_match(const char *list, const char *addr, const char **host_ptr) |
| 242 | { |
| 243 | char *tok; |
| 244 | char *list2 = strdup(list); |
| 245 | |
| 246 | if (!list2) |
| 247 | out_of_memory("access_match"); |
| 248 | |
| 249 | strlower(list2); |
| 250 | |
| 251 | for (tok = strtok(list2, " ,\t"); tok; tok = strtok(NULL, " ,\t")) { |
| 252 | if (match_hostname(host_ptr, addr, tok) || match_address(addr, tok)) { |
| 253 | free(list2); |
| 254 | return 1; |
| 255 | } |
| 256 | } |
| 257 | |
| 258 | free(list2); |
| 259 | return 0; |
| 260 | } |
| 261 | |
| 262 | int allow_access(const char *addr, const char **host_ptr, int i) |
| 263 | { |
| 264 | const char *allow_list = lp_hosts_allow(i); |
| 265 | const char *deny_list = lp_hosts_deny(i); |
| 266 | |
| 267 | if (allow_list && !*allow_list) |
| 268 | allow_list = NULL; |
| 269 | if (deny_list && !*deny_list) |
| 270 | deny_list = NULL; |
| 271 | |
| 272 | allow_forward_dns = lp_forward_lookup(i); |
| 273 | |
| 274 | /* If we match an allow-list item, we always allow access. */ |
| 275 | if (allow_list) { |
| 276 | if (access_match(allow_list, addr, host_ptr)) |
| 277 | return 1; |
| 278 | /* For an allow-list w/o a deny-list, disallow non-matches. */ |
| 279 | if (!deny_list) |
| 280 | return 0; |
| 281 | } |
| 282 | |
| 283 | /* If we match a deny-list item (and got past any allow-list |
| 284 | * items), we always disallow access. */ |
| 285 | if (deny_list && access_match(deny_list, addr, host_ptr)) |
| 286 | return 0; |
| 287 | |
| 288 | /* Allow all other access. */ |
| 289 | return 1; |
| 290 | } |