crypto/openssh/addrmatch.c

   1 /*      $OpenBSD: addrmatch.c,v 1.10 2015/07/08 19:04:21 markus 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
  35 struct xaddr {
  36         sa_family_t     af;
  37         union {
  38                 struct in_addr          v4;
  39                 struct in6_addr         v6;
  40                 u_int8_t                addr8[16];
  41                 u_int32_t               addr32[4];
  42         } xa;               /* 128-bit address */
  43         u_int32_t       scope_id;       /* iface scope id for v6 */
  44 #define v4      xa.v4
  45 #define v6      xa.v6
  46 #define addr8   xa.addr8
  47 #define addr32  xa.addr32
  48 };
  49
  50 static int
  51 addr_unicast_masklen(int af)
  52 {
  53         switch (af) {
  54         case AF_INET:
  55                 return 32;
  56         case AF_INET6:
  57                 return 128;
  58         default:
  59                 return -1;
  60         }
  61 }
  62
  63 static inline int
  64 masklen_valid(int af, u_int masklen)
  65 {
  66         switch (af) {
  67         case AF_INET:
  68                 return masklen <= 32 ? 0 : -1;
  69         case AF_INET6:
  70                 return masklen <= 128 ? 0 : -1;
  71         default:
  72                 return -1;
  73         }
  74 }
  75
  76 /*
  77  * Convert struct sockaddr to struct xaddr
  78  * Returns 0 on success, -1 on failure.
  79  */
  80 static int
  81 addr_sa_to_xaddr(struct sockaddr *sa, socklen_t slen, struct xaddr *xa)
  82 {
  83         struct sockaddr_in *in4 = (struct sockaddr_in *)sa;
  84         struct sockaddr_in6 *in6 = (struct sockaddr_in6 *)sa;
  85
  86         memset(xa, '\0', sizeof(*xa));
  87
  88         switch (sa->sa_family) {
  89         case AF_INET:
  90                 if (slen < (socklen_t)sizeof(*in4))
  91                         return -1;
  92                 xa->af = AF_INET;
  93                 memcpy(&xa->v4, &in4->sin_addr, sizeof(xa->v4));
  94                 break;
  95         case AF_INET6:
  96                 if (slen < (socklen_t)sizeof(*in6))
  97                         return -1;
  98                 xa->af = AF_INET6;
  99                 memcpy(&xa->v6, &in6->sin6_addr, sizeof(xa->v6));
 100 #ifdef HAVE_STRUCT_SOCKADDR_IN6_SIN6_SCOPE_ID
 101                 xa->scope_id = in6->sin6_scope_id;
 102 #endif
 103                 break;
 104         default:
 105                 return -1;
 106         }
 107
 108         return 0;
 109 }
 110
 111 /*
 112  * Calculate a netmask of length 'l' for address family 'af' and
 113  * store it in 'n'.
 114  * Returns 0 on success, -1 on failure.
 115  */
 116 static int
 117 addr_netmask(int af, u_int l, struct xaddr *n)
 118 {
 119         int i;
 120
 121         if (masklen_valid(af, l) != 0 || n == NULL)
 122                 return -1;
 123
 124         memset(n, '\0', sizeof(*n));
 125         switch (af) {
 126         case AF_INET:
 127                 n->af = AF_INET;
 128                 if (l == 0)
 129                         return 0;
 130                 n->v4.s_addr = htonl((0xffffffff << (32 - l)) & 0xffffffff);
 131                 return 0;
 132         case AF_INET6:
 133                 n->af = AF_INET6;
 134                 for (i = 0; i < 4 && l >= 32; i++, l -= 32)
 135                         n->addr32[i] = 0xffffffffU;
 136                 if (i < 4 && l != 0)
 137                         n->addr32[i] = htonl((0xffffffff << (32 - l)) &
 138                             0xffffffff);
 139                 return 0;
 140         default:
 141                 return -1;
 142         }
 143 }
 144
 145 /*
 146  * Perform logical AND of addresses 'a' and 'b', storing result in 'dst'.
 147  * Returns 0 on success, -1 on failure.
 148  */
 149 static int
 150 addr_and(struct xaddr *dst, const struct xaddr *a, const struct xaddr *b)
 151 {
 152         int i;
 153
 154         if (dst == NULL || a == NULL || b == NULL || a->af != b->af)
 155                 return -1;
 156
 157         memcpy(dst, a, sizeof(*dst));
 158         switch (a->af) {
 159         case AF_INET:
 160                 dst->v4.s_addr &= b->v4.s_addr;
 161                 return 0;
 162         case AF_INET6:
 163                 dst->scope_id = a->scope_id;
 164                 for (i = 0; i < 4; i++)
 165                         dst->addr32[i] &= b->addr32[i];
 166                 return 0;
 167         default:
 168                 return -1;
 169         }
 170 }
 171
 172 /*
 173  * Compare addresses 'a' and 'b'
 174  * Return 0 if addresses are identical, -1 if (a < b) or 1 if (a > b)
 175  */
 176 static int
 177 addr_cmp(const struct xaddr *a, const struct xaddr *b)
 178 {
 179         int i;
 180
 181         if (a->af != b->af)
 182                 return a->af == AF_INET6 ? 1 : -1;
 183
 184         switch (a->af) {
 185         case AF_INET:
 186                 if (a->v4.s_addr == b->v4.s_addr)
 187                         return 0;
 188                 return ntohl(a->v4.s_addr) > ntohl(b->v4.s_addr) ? 1 : -1;
 189         case AF_INET6:
 190                 for (i = 0; i < 16; i++)
 191                         if (a->addr8[i] - b->addr8[i] != 0)
 192                                 return a->addr8[i] > b->addr8[i] ? 1 : -1;
 193                 if (a->scope_id == b->scope_id)
 194                         return 0;
 195                 return a->scope_id > b->scope_id ? 1 : -1;
 196         default:
 197                 return -1;
 198         }
 199 }
 200
 201 /*
 202  * Parse string address 'p' into 'n'
 203  * Returns 0 on success, -1 on failure.
 204  */
 205 static int
 206 addr_pton(const char *p, struct xaddr *n)
 207 {
 208         struct addrinfo hints, *ai;
 209
 210         memset(&hints, '\0', sizeof(hints));
 211         hints.ai_flags = AI_NUMERICHOST;
 212
 213         if (p == NULL || getaddrinfo(p, NULL, &hints, &ai) != 0)
 214                 return -1;
 215
 216         if (ai == NULL || ai->ai_addr == NULL)
 217                 return -1;
 218
 219         if (n != NULL &&
 220             addr_sa_to_xaddr(ai->ai_addr, ai->ai_addrlen, n) == -1) {
 221                 freeaddrinfo(ai);
 222                 return -1;
 223         }
 224
 225         freeaddrinfo(ai);
 226         return 0;
 227 }
 228
 229 /*
 230  * Perform bitwise negation of address
 231  * Returns 0 on success, -1 on failure.
 232  */
 233 static int
 234 addr_invert(struct xaddr *n)
 235 {
 236         int i;
 237
 238         if (n == NULL)
 239                 return (-1);
 240
 241         switch (n->af) {
 242         case AF_INET:
 243                 n->v4.s_addr = ~n->v4.s_addr;
 244                 return (0);
 245         case AF_INET6:
 246                 for (i = 0; i < 4; i++)
 247                         n->addr32[i] = ~n->addr32[i];
 248                 return (0);
 249         default:
 250                 return (-1);
 251         }
 252 }
 253
 254 /*
 255  * Calculate a netmask of length 'l' for address family 'af' and
 256  * store it in 'n'.
 257  * Returns 0 on success, -1 on failure.
 258  */
 259 static int
 260 addr_hostmask(int af, u_int l, struct xaddr *n)
 261 {
 262         if (addr_netmask(af, l, n) == -1 || addr_invert(n) == -1)
 263                 return (-1);
 264         return (0);
 265 }
 266
 267 /*
 268  * Test whether address 'a' is all zeros (i.e. 0.0.0.0 or ::)
 269  * Returns 0 on if address is all-zeros, -1 if not all zeros or on failure.
 270  */
 271 static int
 272 addr_is_all0s(const struct xaddr *a)
 273 {
 274         int i;
 275
 276         switch (a->af) {
 277         case AF_INET:
 278                 return (a->v4.s_addr == 0 ? 0 : -1);
 279         case AF_INET6:;
 280                 for (i = 0; i < 4; i++)
 281                         if (a->addr32[i] != 0)
 282                                 return (-1);
 283                 return (0);
 284         default:
 285                 return (-1);
 286         }
 287 }
 288
 289 /*
 290  * Test whether host portion of address 'a', as determined by 'masklen'
 291  * is all zeros.
 292  * Returns 0 on if host portion of address is all-zeros,
 293  * -1 if not all zeros or on failure.
 294  */
 295 static int
 296 addr_host_is_all0s(const struct xaddr *a, u_int masklen)
 297 {
 298         struct xaddr tmp_addr, tmp_mask, tmp_result;
 299
 300         memcpy(&tmp_addr, a, sizeof(tmp_addr));
 301         if (addr_hostmask(a->af, masklen, &tmp_mask) == -1)
 302                 return (-1);
 303         if (addr_and(&tmp_result, &tmp_addr, &tmp_mask) == -1)
 304                 return (-1);
 305         return (addr_is_all0s(&tmp_result));
 306 }
 307
 308 /*
 309  * Parse a CIDR address (x.x.x.x/y or xxxx:yyyy::/z).
 310  * Return -1 on parse error, -2 on inconsistency or 0 on success.
 311  */
 312 static int
 313 addr_pton_cidr(const char *p, struct xaddr *n, u_int *l)
 314 {
 315         struct xaddr tmp;
 316         long unsigned int masklen = 999;
 317         char addrbuf[64], *mp, *cp;
 318
 319         /* Don't modify argument */
 320         if (p == NULL || strlcpy(addrbuf, p, sizeof(addrbuf)) >= sizeof(addrbuf))
 321                 return -1;
 322
 323         if ((mp = strchr(addrbuf, '/')) != NULL) {
 324                 *mp = '\0';
 325                 mp++;
 326                 masklen = strtoul(mp, &cp, 10);
 327                 if (*mp == '\0' || *cp != '\0' || masklen > 128)
 328                         return -1;
 329         }
 330
 331         if (addr_pton(addrbuf, &tmp) == -1)
 332                 return -1;
 333
 334         if (mp == NULL)
 335                 masklen = addr_unicast_masklen(tmp.af);
 336         if (masklen_valid(tmp.af, masklen) == -1)
 337                 return -2;
 338         if (addr_host_is_all0s(&tmp, masklen) != 0)
 339                 return -2;
 340
 341         if (n != NULL)
 342                 memcpy(n, &tmp, sizeof(*n));
 343         if (l != NULL)
 344                 *l = masklen;
 345
 346         return 0;
 347 }
 348
 349 static int
 350 addr_netmatch(const struct xaddr *host, const struct xaddr *net, u_int masklen)
 351 {
 352         struct xaddr tmp_mask, tmp_result;
 353
 354         if (host->af != net->af)
 355                 return -1;
 356
 357         if (addr_netmask(host->af, masklen, &tmp_mask) == -1)
 358                 return -1;
 359         if (addr_and(&tmp_result, host, &tmp_mask) == -1)
 360                 return -1;
 361         return addr_cmp(&tmp_result, net);
 362 }
 363
 364 /*
 365  * Match "addr" against list pattern list "_list", which may contain a
 366  * mix of CIDR addresses and old-school wildcards.
 367  *
 368  * If addr is NULL, then no matching is performed, but _list is parsed
 369  * and checked for well-formedness.
 370  *
 371  * Returns 1 on match found (never returned when addr == NULL).
 372  * Returns 0 on if no match found, or no errors found when addr == NULL.
 373  * Returns -1 on negated match found (never returned when addr == NULL).
 374  * Returns -2 on invalid list entry.
 375  */
 376 int
 377 addr_match_list(const char *addr, const char *_list)
 378 {
 379         char *list, *cp, *o;
 380         struct xaddr try_addr, match_addr;
 381         u_int masklen, neg;
 382         int ret = 0, r;
 383
 384         if (addr != NULL && addr_pton(addr, &try_addr) != 0) {
 385                 debug2("%s: couldn't parse address %.100s", __func__, addr);
 386                 return 0;
 387         }
 388         if ((o = list = strdup(_list)) == NULL)
 389                 return -1;
 390         while ((cp = strsep(&list, ",")) != NULL) {
 391                 neg = *cp == '!';
 392                 if (neg)
 393                         cp++;
 394                 if (*cp == '\0') {
 395                         ret = -2;
 396                         break;
 397                 }
 398                 /* Prefer CIDR address matching */
 399                 r = addr_pton_cidr(cp, &match_addr, &masklen);
 400                 if (r == -2) {
 401                         error("Inconsistent mask length for "
 402                             "network \"%.100s\"", cp);
 403                         ret = -2;
 404                         break;
 405                 } else if (r == 0) {
 406                         if (addr != NULL && addr_netmatch(&try_addr,
 407                            &match_addr, masklen) == 0) {
 408  foundit:
 409                                 if (neg) {
 410                                         ret = -1;
 411                                         break;
 412                                 }
 413                                 ret = 1;
 414                         }
 415                         continue;
 416                 } else {
 417                         /* If CIDR parse failed, try wildcard string match */
 418                         if (addr != NULL && match_pattern(addr, cp) == 1)
 419                                 goto foundit;
 420                 }
 421         }
 422         free(o);
 423
 424         return ret;
 425 }
 426
 427 /*
 428  * Match "addr" against list CIDR list "_list". Lexical wildcards and
 429  * negation are not supported. If "addr" == NULL, will verify structure
 430  * of "_list".
 431  *
 432  * Returns 1 on match found (never returned when addr == NULL).
 433  * Returns 0 on if no match found, or no errors found when addr == NULL.
 434  * Returns -1 on error
 435  */
 436 int
 437 addr_match_cidr_list(const char *addr, const char *_list)
 438 {
 439         char *list, *cp, *o;
 440         struct xaddr try_addr, match_addr;
 441         u_int masklen;
 442         int ret = 0, r;
 443
 444         if (addr != NULL && addr_pton(addr, &try_addr) != 0) {
 445                 debug2("%s: couldn't parse address %.100s", __func__, addr);
 446                 return 0;
 447         }
 448         if ((o = list = strdup(_list)) == NULL)
 449                 return -1;
 450         while ((cp = strsep(&list, ",")) != NULL) {
 451                 if (*cp == '\0') {
 452                         error("%s: empty entry in list \"%.100s\"",
 453                             __func__, o);
 454                         ret = -1;
 455                         break;
 456                 }
 457
 458                 /*
 459                  * NB. This function is called in pre-auth with untrusted data,
 460                  * so be extra paranoid about junk reaching getaddrino (via
 461                  * addr_pton_cidr).
 462                  */
 463
 464                 /* Stop junk from reaching getaddrinfo. +3 is for masklen */
 465                 if (strlen(cp) > INET6_ADDRSTRLEN + 3) {
 466                         error("%s: list entry \"%.100s\" too long",
 467                             __func__, cp);
 468                         ret = -1;
 469                         break;
 470                 }
 471 #define VALID_CIDR_CHARS "0123456789abcdefABCDEF.:/"
 472                 if (strspn(cp, VALID_CIDR_CHARS) != strlen(cp)) {
 473                         error("%s: list entry \"%.100s\" contains invalid "
 474                             "characters", __func__, cp);
 475                         ret = -1;
 476                 }
 477
 478                 /* Prefer CIDR address matching */
 479                 r = addr_pton_cidr(cp, &match_addr, &masklen);
 480                 if (r == -1) {
 481                         error("Invalid network entry \"%.100s\"", cp);
 482                         ret = -1;
 483                         break;
 484                 } else if (r == -2) {
 485                         error("Inconsistent mask length for "
 486                             "network \"%.100s\"", cp);
 487                         ret = -1;
 488                         break;
 489                 } else if (r == 0 && addr != NULL) {
 490                         if (addr_netmatch(&try_addr, &match_addr,
 491                             masklen) == 0)
 492                                 ret = 1;
 493                         continue;
 494                 }
 495         }
 496         free(o);
 497
 498         return ret;
 499 }