crypto/openssh/addrmatch.c

   1 /*      $OpenBSD: addrmatch.c,v 1.9 2014/01/19 11:21:51 dtucker Exp $ */
   2
   3 /*
   4  * Copyright (c) 2004-2008 Damien Miller <djm@mindrot.org>
   5  *
   6  * Permission to use, copy, modify, and distribute this software for any
   7  * purpose with or without fee is hereby granted, provided that the above
   8  * copyright notice and this permission notice appear in all copies.
   9  *
  10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  11  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  12  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  13  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  14  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  15  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  16  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  17  */
  18
  19 #include "includes.h"
  20
  21 #include <sys/types.h>
  22 #include <sys/socket.h>
  23 #include <netinet/in.h>
  24 #include <arpa/inet.h>
  25
  26 #include <netdb.h>
  27 #include <string.h>
  28 #include <stdlib.h>
  29 #include <stdio.h>
  30 #include <stdarg.h>
  31
  32 #include "match.h"
  33 #include "log.h"
  34 #include "xmalloc.h"
  35
  36 struct xaddr {
  37         sa_family_t     af;
  38         union {
  39                 struct in_addr          v4;
  40                 struct in6_addr         v6;
  41                 u_int8_t                addr8[16];
  42                 u_int32_t               addr32[4];
  43         } xa;               /* 128-bit address */
  44         u_int32_t       scope_id;       /* iface scope id for v6 */
  45 #define v4      xa.v4
  46 #define v6      xa.v6
  47 #define addr8   xa.addr8
  48 #define addr32  xa.addr32
  49 };
  50
  51 static int
  52 addr_unicast_masklen(int af)
  53 {
  54         switch (af) {
  55         case AF_INET:
  56                 return 32;
  57         case AF_INET6:
  58                 return 128;
  59         default:
  60                 return -1;
  61         }
  62 }
  63
  64 static inline int
  65 masklen_valid(int af, u_int masklen)
  66 {
  67         switch (af) {
  68         case AF_INET:
  69                 return masklen <= 32 ? 0 : -1;
  70         case AF_INET6:
  71                 return masklen <= 128 ? 0 : -1;
  72         default:
  73                 return -1;
  74         }
  75 }
  76
  77 /*
  78  * Convert struct sockaddr to struct xaddr
  79  * Returns 0 on success, -1 on failure.
  80  */
  81 static int
  82 addr_sa_to_xaddr(struct sockaddr *sa, socklen_t slen, struct xaddr *xa)
  83 {
  84         struct sockaddr_in *in4 = (struct sockaddr_in *)sa;
  85         struct sockaddr_in6 *in6 = (struct sockaddr_in6 *)sa;
  86
  87         memset(xa, '\0', sizeof(*xa));
  88
  89         switch (sa->sa_family) {
  90         case AF_INET:
  91                 if (slen < (socklen_t)sizeof(*in4))
  92                         return -1;
  93                 xa->af = AF_INET;
  94                 memcpy(&xa->v4, &in4->sin_addr, sizeof(xa->v4));
  95                 break;
  96         case AF_INET6:
  97                 if (slen < (socklen_t)sizeof(*in6))
  98                         return -1;
  99                 xa->af = AF_INET6;
 100                 memcpy(&xa->v6, &in6->sin6_addr, sizeof(xa->v6));
 101 #ifdef HAVE_STRUCT_SOCKADDR_IN6_SIN6_SCOPE_ID
 102                 xa->scope_id = in6->sin6_scope_id;
 103 #endif
 104                 break;
 105         default:
 106                 return -1;
 107         }
 108
 109         return 0;
 110 }
 111
 112 /*
 113  * Calculate a netmask of length 'l' for address family 'af' and
 114  * store it in 'n'.
 115  * Returns 0 on success, -1 on failure.
 116  */
 117 static int
 118 addr_netmask(int af, u_int l, struct xaddr *n)
 119 {
 120         int i;
 121
 122         if (masklen_valid(af, l) != 0 || n == NULL)
 123                 return -1;
 124
 125         memset(n, '\0', sizeof(*n));
 126         switch (af) {
 127         case AF_INET:
 128                 n->af = AF_INET;
 129                 if (l == 0)
 130                         return 0;
 131                 n->v4.s_addr = htonl((0xffffffff << (32 - l)) & 0xffffffff);
 132                 return 0;
 133         case AF_INET6:
 134                 n->af = AF_INET6;
 135                 for (i = 0; i < 4 && l >= 32; i++, l -= 32)
 136                         n->addr32[i] = 0xffffffffU;
 137                 if (i < 4 && l != 0)
 138                         n->addr32[i] = htonl((0xffffffff << (32 - l)) &
 139                             0xffffffff);
 140                 return 0;
 141         default:
 142                 return -1;
 143         }
 144 }
 145
 146 /*
 147  * Perform logical AND of addresses 'a' and 'b', storing result in 'dst'.
 148  * Returns 0 on success, -1 on failure.
 149  */
 150 static int
 151 addr_and(struct xaddr *dst, const struct xaddr *a, const struct xaddr *b)
 152 {
 153         int i;
 154
 155         if (dst == NULL || a == NULL || b == NULL || a->af != b->af)
 156                 return -1;
 157
 158         memcpy(dst, a, sizeof(*dst));
 159         switch (a->af) {
 160         case AF_INET:
 161                 dst->v4.s_addr &= b->v4.s_addr;
 162                 return 0;
 163         case AF_INET6:
 164                 dst->scope_id = a->scope_id;
 165                 for (i = 0; i < 4; i++)
 166                         dst->addr32[i] &= b->addr32[i];
 167                 return 0;
 168         default:
 169                 return -1;
 170         }
 171 }
 172
 173 /*
 174  * Compare addresses 'a' and 'b'
 175  * Return 0 if addresses are identical, -1 if (a < b) or 1 if (a > b)
 176  */
 177 static int
 178 addr_cmp(const struct xaddr *a, const struct xaddr *b)
 179 {
 180         int i;
 181
 182         if (a->af != b->af)
 183                 return a->af == AF_INET6 ? 1 : -1;
 184
 185         switch (a->af) {
 186         case AF_INET:
 187                 if (a->v4.s_addr == b->v4.s_addr)
 188                         return 0;
 189                 return ntohl(a->v4.s_addr) > ntohl(b->v4.s_addr) ? 1 : -1;
 190         case AF_INET6:
 191                 for (i = 0; i < 16; i++)
 192                         if (a->addr8[i] - b->addr8[i] != 0)
 193                                 return a->addr8[i] > b->addr8[i] ? 1 : -1;
 194                 if (a->scope_id == b->scope_id)
 195                         return 0;
 196                 return a->scope_id > b->scope_id ? 1 : -1;
 197         default:
 198                 return -1;
 199         }
 200 }
 201
 202 /*
 203  * Parse string address 'p' into 'n'
 204  * Returns 0 on success, -1 on failure.
 205  */
 206 static int
 207 addr_pton(const char *p, struct xaddr *n)
 208 {
 209         struct addrinfo hints, *ai;
 210
 211         memset(&hints, '\0', sizeof(hints));
 212         hints.ai_flags = AI_NUMERICHOST;
 213
 214         if (p == NULL || getaddrinfo(p, NULL, &hints, &ai) != 0)
 215                 return -1;
 216
 217         if (ai == NULL || ai->ai_addr == NULL)
 218                 return -1;
 219
 220         if (n != NULL &&
 221             addr_sa_to_xaddr(ai->ai_addr, ai->ai_addrlen, n) == -1) {
 222                 freeaddrinfo(ai);
 223                 return -1;
 224         }
 225
 226         freeaddrinfo(ai);
 227         return 0;
 228 }
 229
 230 /*
 231  * Perform bitwise negation of address
 232  * Returns 0 on success, -1 on failure.
 233  */
 234 static int
 235 addr_invert(struct xaddr *n)
 236 {
 237         int i;
 238
 239         if (n == NULL)
 240                 return (-1);
 241
 242         switch (n->af) {
 243         case AF_INET:
 244                 n->v4.s_addr = ~n->v4.s_addr;
 245                 return (0);
 246         case AF_INET6:
 247                 for (i = 0; i < 4; i++)
 248                         n->addr32[i] = ~n->addr32[i];
 249                 return (0);
 250         default:
 251                 return (-1);
 252         }
 253 }
 254
 255 /*
 256  * Calculate a netmask of length 'l' for address family 'af' and
 257  * store it in 'n'.
 258  * Returns 0 on success, -1 on failure.
 259  */
 260 static int
 261 addr_hostmask(int af, u_int l, struct xaddr *n)
 262 {
 263         if (addr_netmask(af, l, n) == -1 || addr_invert(n) == -1)
 264                 return (-1);
 265         return (0);
 266 }
 267
 268 /*
 269  * Test whether address 'a' is all zeros (i.e. 0.0.0.0 or ::)
 270  * Returns 0 on if address is all-zeros, -1 if not all zeros or on failure.
 271  */
 272 static int
 273 addr_is_all0s(const struct xaddr *a)
 274 {
 275         int i;
 276
 277         switch (a->af) {
 278         case AF_INET:
 279                 return (a->v4.s_addr == 0 ? 0 : -1);
 280         case AF_INET6:;
 281                 for (i = 0; i < 4; i++)
 282                         if (a->addr32[i] != 0)
 283                                 return (-1);
 284                 return (0);
 285         default:
 286                 return (-1);
 287         }
 288 }
 289
 290 /*
 291  * Test whether host portion of address 'a', as determined by 'masklen'
 292  * is all zeros.
 293  * Returns 0 on if host portion of address is all-zeros,
 294  * -1 if not all zeros or on failure.
 295  */
 296 static int
 297 addr_host_is_all0s(const struct xaddr *a, u_int masklen)
 298 {
 299         struct xaddr tmp_addr, tmp_mask, tmp_result;
 300
 301         memcpy(&tmp_addr, a, sizeof(tmp_addr));
 302         if (addr_hostmask(a->af, masklen, &tmp_mask) == -1)
 303                 return (-1);
 304         if (addr_and(&tmp_result, &tmp_addr, &tmp_mask) == -1)
 305                 return (-1);
 306         return (addr_is_all0s(&tmp_result));
 307 }
 308
 309 /*
 310  * Parse a CIDR address (x.x.x.x/y or xxxx:yyyy::/z).
 311  * Return -1 on parse error, -2 on inconsistency or 0 on success.
 312  */
 313 static int
 314 addr_pton_cidr(const char *p, struct xaddr *n, u_int *l)
 315 {
 316         struct xaddr tmp;
 317         long unsigned int masklen = 999;
 318         char addrbuf[64], *mp, *cp;
 319
 320         /* Don't modify argument */
 321         if (p == NULL || strlcpy(addrbuf, p, sizeof(addrbuf)) >= sizeof(addrbuf))
 322                 return -1;
 323
 324         if ((mp = strchr(addrbuf, '/')) != NULL) {
 325                 *mp = '\0';
 326                 mp++;
 327                 masklen = strtoul(mp, &cp, 10);
 328                 if (*mp == '\0' || *cp != '\0' || masklen > 128)
 329                         return -1;
 330         }
 331
 332         if (addr_pton(addrbuf, &tmp) == -1)
 333                 return -1;
 334
 335         if (mp == NULL)
 336                 masklen = addr_unicast_masklen(tmp.af);
 337         if (masklen_valid(tmp.af, masklen) == -1)
 338                 return -2;
 339         if (addr_host_is_all0s(&tmp, masklen) != 0)
 340                 return -2;
 341
 342         if (n != NULL)
 343                 memcpy(n, &tmp, sizeof(*n));
 344         if (l != NULL)
 345                 *l = masklen;
 346
 347         return 0;
 348 }
 349
 350 static int
 351 addr_netmatch(const struct xaddr *host, const struct xaddr *net, u_int masklen)
 352 {
 353         struct xaddr tmp_mask, tmp_result;
 354
 355         if (host->af != net->af)
 356                 return -1;
 357
 358         if (addr_netmask(host->af, masklen, &tmp_mask) == -1)
 359                 return -1;
 360         if (addr_and(&tmp_result, host, &tmp_mask) == -1)
 361                 return -1;
 362         return addr_cmp(&tmp_result, net);
 363 }
 364
 365 /*
 366  * Match "addr" against list pattern list "_list", which may contain a
 367  * mix of CIDR addresses and old-school wildcards.
 368  *
 369  * If addr is NULL, then no matching is performed, but _list is parsed
 370  * and checked for well-formedness.
 371  *
 372  * Returns 1 on match found (never returned when addr == NULL).
 373  * Returns 0 on if no match found, or no errors found when addr == NULL.
 374  * Returns -1 on negated match found (never returned when addr == NULL).
 375  * Returns -2 on invalid list entry.
 376  */
 377 int
 378 addr_match_list(const char *addr, const char *_list)
 379 {
 380         char *list, *cp, *o;
 381         struct xaddr try_addr, match_addr;
 382         u_int masklen, neg;
 383         int ret = 0, r;
 384
 385         if (addr != NULL && addr_pton(addr, &try_addr) != 0) {
 386                 debug2("%s: couldn't parse address %.100s", __func__, addr);
 387                 return 0;
 388         }
 389         if ((o = list = strdup(_list)) == NULL)
 390                 return -1;
 391         while ((cp = strsep(&list, ",")) != NULL) {
 392                 neg = *cp == '!';
 393                 if (neg)
 394                         cp++;
 395                 if (*cp == '\0') {
 396                         ret = -2;
 397                         break;
 398                 }
 399                 /* Prefer CIDR address matching */
 400                 r = addr_pton_cidr(cp, &match_addr, &masklen);
 401                 if (r == -2) {
 402                         error("Inconsistent mask length for "
 403                             "network \"%.100s\"", cp);
 404                         ret = -2;
 405                         break;
 406                 } else if (r == 0) {
 407                         if (addr != NULL && addr_netmatch(&try_addr,
 408                            &match_addr, masklen) == 0) {
 409  foundit:
 410                                 if (neg) {
 411                                         ret = -1;
 412                                         break;
 413                                 }
 414                                 ret = 1;
 415                         }
 416                         continue;
 417                 } else {
 418                         /* If CIDR parse failed, try wildcard string match */
 419                         if (addr != NULL && match_pattern(addr, cp) == 1)
 420                                 goto foundit;
 421                 }
 422         }
 423         free(o);
 424
 425         return ret;
 426 }
 427
 428 /*
 429  * Match "addr" against list CIDR list "_list". Lexical wildcards and
 430  * negation are not supported. If "addr" == NULL, will verify structure
 431  * of "_list".
 432  *
 433  * Returns 1 on match found (never returned when addr == NULL).
 434  * Returns 0 on if no match found, or no errors found when addr == NULL.
 435  * Returns -1 on error
 436  */
 437 int
 438 addr_match_cidr_list(const char *addr, const char *_list)
 439 {
 440         char *list, *cp, *o;
 441         struct xaddr try_addr, match_addr;
 442         u_int masklen;
 443         int ret = 0, r;
 444
 445         if (addr != NULL && addr_pton(addr, &try_addr) != 0) {
 446                 debug2("%s: couldn't parse address %.100s", __func__, addr);
 447                 return 0;
 448         }
 449         if ((o = list = strdup(_list)) == NULL)
 450                 return -1;
 451         while ((cp = strsep(&list, ",")) != NULL) {
 452                 if (*cp == '\0') {
 453                         error("%s: empty entry in list \"%.100s\"",
 454                             __func__, o);
 455                         ret = -1;
 456                         break;
 457                 }
 458
 459                 /*
 460                  * NB. This function is called in pre-auth with untrusted data,
 461                  * so be extra paranoid about junk reaching getaddrino (via
 462                  * addr_pton_cidr).
 463                  */
 464
 465                 /* Stop junk from reaching getaddrinfo. +3 is for masklen */
 466                 if (strlen(cp) > INET6_ADDRSTRLEN + 3) {
 467                         error("%s: list entry \"%.100s\" too long",
 468                             __func__, cp);
 469                         ret = -1;
 470                         break;
 471                 }
 472 #define VALID_CIDR_CHARS "0123456789abcdefABCDEF.:/"
 473                 if (strspn(cp, VALID_CIDR_CHARS) != strlen(cp)) {
 474                         error("%s: list entry \"%.100s\" contains invalid "
 475                             "characters", __func__, cp);
 476                         ret = -1;
 477                 }
 478
 479                 /* Prefer CIDR address matching */
 480                 r = addr_pton_cidr(cp, &match_addr, &masklen);
 481                 if (r == -1) {
 482                         error("Invalid network entry \"%.100s\"", cp);
 483                         ret = -1;
 484                         break;
 485                 } else if (r == -2) {
 486                         error("Inconsistent mask length for "
 487                             "network \"%.100s\"", cp);
 488                         ret = -1;
 489                         break;
 490                 } else if (r == 0 && addr != NULL) {
 491                         if (addr_netmatch(&try_addr, &match_addr,
 492                             masklen) == 0)
 493                                 ret = 1;
 494                         continue;
 495                 }
 496         }
 497         free(o);
 498
 499         return ret;
 500 }