1264377Sdes/* $OpenBSD: hostfile.c,v 1.55 2014/01/31 16:39:19 tedu Exp $ */ 257429Smarkm/* 357429Smarkm * Author: Tatu Ylonen <ylo@cs.hut.fi> 457429Smarkm * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 557429Smarkm * All rights reserved 665674Skris * Functions for manipulating the known hosts files. 760576Skris * 865674Skris * As far as I am concerned, the code I have written for this software 965674Skris * can be used freely for any purpose. Any derived versions of this 1065674Skris * software must be clearly marked as such, and if the derived work is 1165674Skris * incompatible with the protocol description in the RFC file, it must be 1265674Skris * called by a name other than "ssh" or "Secure Shell". 1360576Skris * 1460576Skris * 1592559Sdes * Copyright (c) 1999, 2000 Markus Friedl. All rights reserved. 1665674Skris * Copyright (c) 1999 Niels Provos. All rights reserved. 1765674Skris * 1865674Skris * Redistribution and use in source and binary forms, with or without 1965674Skris * modification, are permitted provided that the following conditions 2065674Skris * are met: 2165674Skris * 1. Redistributions of source code must retain the above copyright 2265674Skris * notice, this list of conditions and the following disclaimer. 2365674Skris * 2. Redistributions in binary form must reproduce the above copyright 2465674Skris * notice, this list of conditions and the following disclaimer in the 2565674Skris * documentation and/or other materials provided with the distribution. 2665674Skris * 2765674Skris * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 2865674Skris * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 2965674Skris * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 3065674Skris * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 3165674Skris * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 3265674Skris * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 3365674Skris * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 3465674Skris * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 3565674Skris * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 3665674Skris * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 3757429Smarkm */ 3857429Smarkm 3957429Smarkm#include "includes.h" 4057429Smarkm 41162856Sdes#include <sys/types.h> 42162856Sdes 43162856Sdes#include <netinet/in.h> 44162856Sdes 45162856Sdes#include <resolv.h> 46162856Sdes#include <stdarg.h> 47162856Sdes#include <stdio.h> 48162856Sdes#include <stdlib.h> 49162856Sdes#include <string.h> 50162856Sdes 51162856Sdes#include "xmalloc.h" 5258582Skris#include "match.h" 5358582Skris#include "key.h" 5458582Skris#include "hostfile.h" 5576262Sgreen#include "log.h" 56221420Sdes#include "misc.h" 57262566Sdes#include "digest.h" 58264377Sdes#include "hmac.h" 5957429Smarkm 60221420Sdesstruct hostkeys { 61221420Sdes struct hostkey_entry *entries; 62221420Sdes u_int num_entries; 63221420Sdes}; 64221420Sdes 65147005Sdesstatic int 66255767Sdesextract_salt(const char *s, u_int l, u_char *salt, size_t salt_len) 67147005Sdes{ 68147005Sdes char *p, *b64salt; 69147005Sdes u_int b64len; 70147005Sdes int ret; 71147005Sdes 72147005Sdes if (l < sizeof(HASH_MAGIC) - 1) { 73147005Sdes debug2("extract_salt: string too short"); 74147005Sdes return (-1); 75147005Sdes } 76147005Sdes if (strncmp(s, HASH_MAGIC, sizeof(HASH_MAGIC) - 1) != 0) { 77147005Sdes debug2("extract_salt: invalid magic identifier"); 78147005Sdes return (-1); 79147005Sdes } 80147005Sdes s += sizeof(HASH_MAGIC) - 1; 81147005Sdes l -= sizeof(HASH_MAGIC) - 1; 82147005Sdes if ((p = memchr(s, HASH_DELIM, l)) == NULL) { 83147005Sdes debug2("extract_salt: missing salt termination character"); 84147005Sdes return (-1); 85147005Sdes } 86147005Sdes 87147005Sdes b64len = p - s; 88147005Sdes /* Sanity check */ 89147005Sdes if (b64len == 0 || b64len > 1024) { 90147005Sdes debug2("extract_salt: bad encoded salt length %u", b64len); 91147005Sdes return (-1); 92147005Sdes } 93147005Sdes b64salt = xmalloc(1 + b64len); 94147005Sdes memcpy(b64salt, s, b64len); 95147005Sdes b64salt[b64len] = '\0'; 96147005Sdes 97147005Sdes ret = __b64_pton(b64salt, salt, salt_len); 98255767Sdes free(b64salt); 99147005Sdes if (ret == -1) { 100147005Sdes debug2("extract_salt: salt decode error"); 101147005Sdes return (-1); 102147005Sdes } 103264377Sdes if (ret != (int)ssh_hmac_bytes(SSH_DIGEST_SHA1)) { 104264377Sdes debug2("extract_salt: expected salt len %zd, got %d", 105264377Sdes ssh_hmac_bytes(SSH_DIGEST_SHA1), ret); 106147005Sdes return (-1); 107147005Sdes } 108147005Sdes 109147005Sdes return (0); 110147005Sdes} 111147005Sdes 112147005Sdeschar * 113147005Sdeshost_hash(const char *host, const char *name_from_hostfile, u_int src_len) 114147005Sdes{ 115264377Sdes struct ssh_hmac_ctx *ctx; 116255767Sdes u_char salt[256], result[256]; 117255767Sdes char uu_salt[512], uu_result[512]; 118147005Sdes static char encoded[1024]; 119147005Sdes u_int i, len; 120147005Sdes 121264377Sdes len = ssh_digest_bytes(SSH_DIGEST_SHA1); 122147005Sdes 123147005Sdes if (name_from_hostfile == NULL) { 124147005Sdes /* Create new salt */ 125147005Sdes for (i = 0; i < len; i++) 126147005Sdes salt[i] = arc4random(); 127147005Sdes } else { 128147005Sdes /* Extract salt from known host entry */ 129147005Sdes if (extract_salt(name_from_hostfile, src_len, salt, 130147005Sdes sizeof(salt)) == -1) 131147005Sdes return (NULL); 132147005Sdes } 133147005Sdes 134264377Sdes if ((ctx = ssh_hmac_start(SSH_DIGEST_SHA1)) == NULL || 135264377Sdes ssh_hmac_init(ctx, salt, len) < 0 || 136264377Sdes ssh_hmac_update(ctx, host, strlen(host)) < 0 || 137264377Sdes ssh_hmac_final(ctx, result, sizeof(result))) 138264377Sdes fatal("%s: ssh_hmac failed", __func__); 139264377Sdes ssh_hmac_free(ctx); 140147005Sdes 141147005Sdes if (__b64_ntop(salt, len, uu_salt, sizeof(uu_salt)) == -1 || 142147005Sdes __b64_ntop(result, len, uu_result, sizeof(uu_result)) == -1) 143264377Sdes fatal("%s: __b64_ntop failed", __func__); 144147005Sdes 145147005Sdes snprintf(encoded, sizeof(encoded), "%s%s%c%s", HASH_MAGIC, uu_salt, 146147005Sdes HASH_DELIM, uu_result); 147147005Sdes 148147005Sdes return (encoded); 149147005Sdes} 150147005Sdes 15157429Smarkm/* 15258582Skris * Parses an RSA (number of bits, e, n) or DSA key from a string. Moves the 15358582Skris * pointer over the key. Skips any whitespace at the beginning and at end. 15457429Smarkm */ 15557429Smarkm 15657429Smarkmint 157255767Sdeshostfile_read_key(char **cpp, int *bitsp, Key *ret) 15857429Smarkm{ 15957429Smarkm char *cp; 16057429Smarkm 16157429Smarkm /* Skip leading whitespace. */ 16257429Smarkm for (cp = *cpp; *cp == ' ' || *cp == '\t'; cp++) 16357429Smarkm ; 16457429Smarkm 16576262Sgreen if (key_read(ret, &cp) != 1) 16657429Smarkm return 0; 16757429Smarkm 16857429Smarkm /* Skip trailing whitespace. */ 16957429Smarkm for (; *cp == ' ' || *cp == '\t'; cp++) 17057429Smarkm ; 17157429Smarkm 17257429Smarkm /* Return results. */ 17357429Smarkm *cpp = cp; 174255767Sdes if (bitsp != NULL) { 175255767Sdes if ((*bitsp = key_size(ret)) <= 0) 176255767Sdes return 0; 177255767Sdes } 17857429Smarkm return 1; 17957429Smarkm} 18057429Smarkm 18192559Sdesstatic int 182221420Sdeshostfile_check_key(int bits, const Key *key, const char *host, 183221420Sdes const char *filename, u_long linenum) 18457429Smarkm{ 18576262Sgreen if (key == NULL || key->type != KEY_RSA1 || key->rsa == NULL) 18658582Skris return 1; 18758582Skris if (bits != BN_num_bits(key->rsa->n)) { 188221420Sdes logit("Warning: %s, line %lu: keysize mismatch for host %s: " 18958582Skris "actual %d vs. announced %d.", 19058582Skris filename, linenum, host, BN_num_bits(key->rsa->n), bits); 191221420Sdes logit("Warning: replace %d with %d in %s, line %lu.", 19258582Skris bits, BN_num_bits(key->rsa->n), filename, linenum); 19357429Smarkm } 19458582Skris return 1; 19557429Smarkm} 19657429Smarkm 197221420Sdesstatic HostkeyMarker 198204917Sdescheck_markers(char **cpp) 199204917Sdes{ 200204917Sdes char marker[32], *sp, *cp = *cpp; 201204917Sdes int ret = MRK_NONE; 202204917Sdes 203204917Sdes while (*cp == '@') { 204204917Sdes /* Only one marker is allowed */ 205204917Sdes if (ret != MRK_NONE) 206204917Sdes return MRK_ERROR; 207204917Sdes /* Markers are terminated by whitespace */ 208204917Sdes if ((sp = strchr(cp, ' ')) == NULL && 209204917Sdes (sp = strchr(cp, '\t')) == NULL) 210204917Sdes return MRK_ERROR; 211204917Sdes /* Extract marker for comparison */ 212204917Sdes if (sp <= cp + 1 || sp >= cp + sizeof(marker)) 213204917Sdes return MRK_ERROR; 214204917Sdes memcpy(marker, cp, sp - cp); 215204917Sdes marker[sp - cp] = '\0'; 216204917Sdes if (strcmp(marker, CA_MARKER) == 0) 217204917Sdes ret = MRK_CA; 218204917Sdes else if (strcmp(marker, REVOKE_MARKER) == 0) 219204917Sdes ret = MRK_REVOKE; 220204917Sdes else 221204917Sdes return MRK_ERROR; 222204917Sdes 223204917Sdes /* Skip past marker and any whitespace that follows it */ 224204917Sdes cp = sp; 225204917Sdes for (; *cp == ' ' || *cp == '\t'; cp++) 226204917Sdes ; 227204917Sdes } 228204917Sdes *cpp = cp; 229204917Sdes return ret; 230204917Sdes} 231204917Sdes 232221420Sdesstruct hostkeys * 233221420Sdesinit_hostkeys(void) 234221420Sdes{ 235221420Sdes struct hostkeys *ret = xcalloc(1, sizeof(*ret)); 23657429Smarkm 237221420Sdes ret->entries = NULL; 238221420Sdes return ret; 239221420Sdes} 240221420Sdes 241221420Sdesvoid 242221420Sdesload_hostkeys(struct hostkeys *hostkeys, const char *host, const char *path) 24357429Smarkm{ 24457429Smarkm FILE *f; 24557429Smarkm char line[8192]; 246221420Sdes u_long linenum = 0, num_loaded = 0; 247147005Sdes char *cp, *cp2, *hashed_host; 248221420Sdes HostkeyMarker marker; 249221420Sdes Key *key; 250221420Sdes int kbits; 25157429Smarkm 252221420Sdes if ((f = fopen(path, "r")) == NULL) 253221420Sdes return; 254221420Sdes debug3("%s: loading entries for host \"%.100s\" from file \"%s\"", 255221420Sdes __func__, host, path); 256221420Sdes while (read_keyfile_line(f, path, line, sizeof(line), &linenum) == 0) { 25757429Smarkm cp = line; 25857429Smarkm 25957429Smarkm /* Skip any leading whitespace, comments and empty lines. */ 26057429Smarkm for (; *cp == ' ' || *cp == '\t'; cp++) 26157429Smarkm ; 26257429Smarkm if (!*cp || *cp == '#' || *cp == '\n') 26357429Smarkm continue; 26457429Smarkm 265221420Sdes if ((marker = check_markers(&cp)) == MRK_ERROR) { 266221420Sdes verbose("%s: invalid marker at %s:%lu", 267221420Sdes __func__, path, linenum); 268204917Sdes continue; 269221420Sdes } 270204917Sdes 27157429Smarkm /* Find the end of the host name portion. */ 27257429Smarkm for (cp2 = cp; *cp2 && *cp2 != ' ' && *cp2 != '\t'; cp2++) 27357429Smarkm ; 27457429Smarkm 27557429Smarkm /* Check if the host name matches. */ 276147005Sdes if (match_hostname(host, cp, (u_int) (cp2 - cp)) != 1) { 277147005Sdes if (*cp != HASH_DELIM) 278147005Sdes continue; 279147005Sdes hashed_host = host_hash(host, cp, (u_int) (cp2 - cp)); 280147005Sdes if (hashed_host == NULL) { 281221420Sdes debug("Invalid hashed host line %lu of %s", 282221420Sdes linenum, path); 283147005Sdes continue; 284147005Sdes } 285147005Sdes if (strncmp(hashed_host, cp, (u_int) (cp2 - cp)) != 0) 286147005Sdes continue; 287147005Sdes } 28857429Smarkm 28957429Smarkm /* Got a match. Skip host name. */ 29057429Smarkm cp = cp2; 29157429Smarkm 29257429Smarkm /* 29357429Smarkm * Extract the key from the line. This will skip any leading 29457429Smarkm * whitespace. Ignore badly formatted lines. 29557429Smarkm */ 296221420Sdes key = key_new(KEY_UNSPEC); 297221420Sdes if (!hostfile_read_key(&cp, &kbits, key)) { 298221420Sdes key_free(key); 299221420Sdes key = key_new(KEY_RSA1); 300221420Sdes if (!hostfile_read_key(&cp, &kbits, key)) { 301221420Sdes key_free(key); 302221420Sdes continue; 303221420Sdes } 304221420Sdes } 305221420Sdes if (!hostfile_check_key(kbits, key, host, path, linenum)) 30657429Smarkm continue; 30757429Smarkm 308221420Sdes debug3("%s: found %skey type %s in file %s:%lu", __func__, 309221420Sdes marker == MRK_NONE ? "" : 310221420Sdes (marker == MRK_CA ? "ca " : "revoked "), 311221420Sdes key_type(key), path, linenum); 312221420Sdes hostkeys->entries = xrealloc(hostkeys->entries, 313221420Sdes hostkeys->num_entries + 1, sizeof(*hostkeys->entries)); 314221420Sdes hostkeys->entries[hostkeys->num_entries].host = xstrdup(host); 315221420Sdes hostkeys->entries[hostkeys->num_entries].file = xstrdup(path); 316221420Sdes hostkeys->entries[hostkeys->num_entries].line = linenum; 317221420Sdes hostkeys->entries[hostkeys->num_entries].key = key; 318221420Sdes hostkeys->entries[hostkeys->num_entries].marker = marker; 319221420Sdes hostkeys->num_entries++; 320221420Sdes num_loaded++; 321221420Sdes } 322221420Sdes debug3("%s: loaded %lu keys", __func__, num_loaded); 323221420Sdes fclose(f); 324221420Sdes return; 325221420Sdes} 32676262Sgreen 327221420Sdesvoid 328221420Sdesfree_hostkeys(struct hostkeys *hostkeys) 329221420Sdes{ 330221420Sdes u_int i; 331221420Sdes 332221420Sdes for (i = 0; i < hostkeys->num_entries; i++) { 333255767Sdes free(hostkeys->entries[i].host); 334255767Sdes free(hostkeys->entries[i].file); 335221420Sdes key_free(hostkeys->entries[i].key); 336264377Sdes explicit_bzero(hostkeys->entries + i, sizeof(*hostkeys->entries)); 337221420Sdes } 338255767Sdes free(hostkeys->entries); 339264377Sdes explicit_bzero(hostkeys, sizeof(*hostkeys)); 340255767Sdes free(hostkeys); 341221420Sdes} 342221420Sdes 343221420Sdesstatic int 344221420Sdescheck_key_not_revoked(struct hostkeys *hostkeys, Key *k) 345221420Sdes{ 346221420Sdes int is_cert = key_is_cert(k); 347221420Sdes u_int i; 348221420Sdes 349221420Sdes for (i = 0; i < hostkeys->num_entries; i++) { 350221420Sdes if (hostkeys->entries[i].marker != MRK_REVOKE) 351106130Sdes continue; 352221420Sdes if (key_equal_public(k, hostkeys->entries[i].key)) 353221420Sdes return -1; 354221420Sdes if (is_cert && 355221420Sdes key_equal_public(k->cert->signature_key, 356221420Sdes hostkeys->entries[i].key)) 357221420Sdes return -1; 358221420Sdes } 359221420Sdes return 0; 360221420Sdes} 361106130Sdes 362221420Sdes/* 363221420Sdes * Match keys against a specified key, or look one up by key type. 364221420Sdes * 365221420Sdes * If looking for a keytype (key == NULL) and one is found then return 366221420Sdes * HOST_FOUND, otherwise HOST_NEW. 367221420Sdes * 368221420Sdes * If looking for a key (key != NULL): 369221420Sdes * 1. If the key is a cert and a matching CA is found, return HOST_OK 370221420Sdes * 2. If the key is not a cert and a matching key is found, return HOST_OK 371221420Sdes * 3. If no key matches but a key with a different type is found, then 372221420Sdes * return HOST_CHANGED 373221420Sdes * 4. If no matching keys are found, then return HOST_NEW. 374221420Sdes * 375221420Sdes * Finally, check any found key is not revoked. 376221420Sdes */ 377221420Sdesstatic HostStatus 378221420Sdescheck_hostkeys_by_key_or_type(struct hostkeys *hostkeys, 379221420Sdes Key *k, int keytype, const struct hostkey_entry **found) 380221420Sdes{ 381221420Sdes u_int i; 382221420Sdes HostStatus end_return = HOST_NEW; 383221420Sdes int want_cert = key_is_cert(k); 384221420Sdes HostkeyMarker want_marker = want_cert ? MRK_CA : MRK_NONE; 385221420Sdes int proto = (k ? k->type : keytype) == KEY_RSA1 ? 1 : 2; 386221420Sdes 387221420Sdes if (found != NULL) 388221420Sdes *found = NULL; 389221420Sdes 390221420Sdes for (i = 0; i < hostkeys->num_entries; i++) { 391221420Sdes if (proto == 1 && hostkeys->entries[i].key->type != KEY_RSA1) 392106130Sdes continue; 393221420Sdes if (proto == 2 && hostkeys->entries[i].key->type == KEY_RSA1) 394221420Sdes continue; 395221420Sdes if (hostkeys->entries[i].marker != want_marker) 396221420Sdes continue; 397221420Sdes if (k == NULL) { 398221420Sdes if (hostkeys->entries[i].key->type != keytype) 399221420Sdes continue; 400221420Sdes end_return = HOST_FOUND; 401221420Sdes if (found != NULL) 402221420Sdes *found = hostkeys->entries + i; 403221420Sdes k = hostkeys->entries[i].key; 404221420Sdes break; 405221420Sdes } 406221420Sdes if (want_cert) { 407221420Sdes if (key_equal_public(k->cert->signature_key, 408221420Sdes hostkeys->entries[i].key)) { 409221420Sdes /* A matching CA exists */ 410221420Sdes end_return = HOST_OK; 411221420Sdes if (found != NULL) 412221420Sdes *found = hostkeys->entries + i; 413221420Sdes break; 414204917Sdes } 415221420Sdes } else { 416221420Sdes if (key_equal(k, hostkeys->entries[i].key)) { 417221420Sdes end_return = HOST_OK; 418221420Sdes if (found != NULL) 419221420Sdes *found = hostkeys->entries + i; 420221420Sdes break; 421204917Sdes } 422221420Sdes /* A non-maching key exists */ 423221420Sdes end_return = HOST_CHANGED; 424221420Sdes if (found != NULL) 425221420Sdes *found = hostkeys->entries + i; 426204917Sdes } 42757429Smarkm } 428221420Sdes if (check_key_not_revoked(hostkeys, k) != 0) { 429221420Sdes end_return = HOST_REVOKED; 430221420Sdes if (found != NULL) 431221420Sdes *found = NULL; 432221420Sdes } 43357429Smarkm return end_return; 43457429Smarkm} 435221420Sdes 436106130SdesHostStatus 437221420Sdescheck_key_in_hostkeys(struct hostkeys *hostkeys, Key *key, 438221420Sdes const struct hostkey_entry **found) 439106130Sdes{ 440106130Sdes if (key == NULL) 441106130Sdes fatal("no key to look up"); 442221420Sdes return check_hostkeys_by_key_or_type(hostkeys, key, 0, found); 443106130Sdes} 444106130Sdes 445106130Sdesint 446221420Sdeslookup_key_in_hostkeys_by_type(struct hostkeys *hostkeys, int keytype, 447221420Sdes const struct hostkey_entry **found) 448106130Sdes{ 449221420Sdes return (check_hostkeys_by_key_or_type(hostkeys, NULL, keytype, 450221420Sdes found) == HOST_FOUND); 451106130Sdes} 452106130Sdes 45357429Smarkm/* 45457429Smarkm * Appends an entry to the host file. Returns false if the entry could not 45557429Smarkm * be appended. 45657429Smarkm */ 45757429Smarkm 45857429Smarkmint 459147005Sdesadd_host_to_hostfile(const char *filename, const char *host, const Key *key, 460147005Sdes int store_hash) 46157429Smarkm{ 46257429Smarkm FILE *f; 46358582Skris int success = 0; 464149753Sdes char *hashed_host = NULL; 465147005Sdes 46658582Skris if (key == NULL) 46760576Skris return 1; /* XXX ? */ 46857429Smarkm f = fopen(filename, "a"); 46957429Smarkm if (!f) 47057429Smarkm return 0; 471147005Sdes 472147005Sdes if (store_hash) { 473147005Sdes if ((hashed_host = host_hash(host, NULL, 0)) == NULL) { 474147005Sdes error("add_host_to_hostfile: host_hash failed"); 475147005Sdes fclose(f); 476147005Sdes return 0; 477147005Sdes } 478147005Sdes } 479147005Sdes fprintf(f, "%s ", store_hash ? hashed_host : host); 480147005Sdes 48158582Skris if (key_write(key, f)) { 48258582Skris success = 1; 48358582Skris } else { 48460576Skris error("add_host_to_hostfile: saving key in %s failed", filename); 48557429Smarkm } 48660576Skris fprintf(f, "\n"); 48757429Smarkm fclose(f); 48858582Skris return success; 48957429Smarkm} 490