| /* $OpenBSD: hostfile.c,v 1.49 2010/11/29 23:45:51 djm Exp $ */ |
| /* |
| * Author: Tatu Ylonen <ylo@cs.hut.fi> |
| * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland |
| * All rights reserved |
| * Functions for manipulating the known hosts files. |
| * |
| * As far as I am concerned, the code I have written for this software |
| * can be used freely for any purpose. Any derived versions of this |
| * software must be clearly marked as such, and if the derived work is |
| * incompatible with the protocol description in the RFC file, it must be |
| * called by a name other than "ssh" or "Secure Shell". |
| * |
| * |
| * Copyright (c) 1999, 2000 Markus Friedl. All rights reserved. |
| * Copyright (c) 1999 Niels Provos. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
| * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
| * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
| * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| #include "includes.h" |
| |
| #include <sys/types.h> |
| |
| #include <netinet/in.h> |
| |
| #include <openssl/hmac.h> |
| #include <openssl/sha.h> |
| |
| #include <resolv.h> |
| #include <stdarg.h> |
| #include <stdio.h> |
| #include <stdlib.h> |
| #include <string.h> |
| |
| #include "xmalloc.h" |
| #include "match.h" |
| #include "key.h" |
| #include "hostfile.h" |
| #include "log.h" |
| #include "misc.h" |
| |
| struct hostkeys { |
| struct hostkey_entry *entries; |
| u_int num_entries; |
| }; |
| |
| static int |
| extract_salt(const char *s, u_int l, char *salt, size_t salt_len) |
| { |
| char *p, *b64salt; |
| u_int b64len; |
| int ret; |
| |
| if (l < sizeof(HASH_MAGIC) - 1) { |
| debug2("extract_salt: string too short"); |
| return (-1); |
| } |
| if (strncmp(s, HASH_MAGIC, sizeof(HASH_MAGIC) - 1) != 0) { |
| debug2("extract_salt: invalid magic identifier"); |
| return (-1); |
| } |
| s += sizeof(HASH_MAGIC) - 1; |
| l -= sizeof(HASH_MAGIC) - 1; |
| if ((p = memchr(s, HASH_DELIM, l)) == NULL) { |
| debug2("extract_salt: missing salt termination character"); |
| return (-1); |
| } |
| |
| b64len = p - s; |
| /* Sanity check */ |
| if (b64len == 0 || b64len > 1024) { |
| debug2("extract_salt: bad encoded salt length %u", b64len); |
| return (-1); |
| } |
| b64salt = xmalloc(1 + b64len); |
| memcpy(b64salt, s, b64len); |
| b64salt[b64len] = '\0'; |
| |
| ret = __b64_pton(b64salt, salt, salt_len); |
| xfree(b64salt); |
| if (ret == -1) { |
| debug2("extract_salt: salt decode error"); |
| return (-1); |
| } |
| if (ret != SHA_DIGEST_LENGTH) { |
| debug2("extract_salt: expected salt len %d, got %d", |
| SHA_DIGEST_LENGTH, ret); |
| return (-1); |
| } |
| |
| return (0); |
| } |
| |
| char * |
| host_hash(const char *host, const char *name_from_hostfile, u_int src_len) |
| { |
| const EVP_MD *md = EVP_sha1(); |
| HMAC_CTX mac_ctx; |
| char salt[256], result[256], uu_salt[512], uu_result[512]; |
| static char encoded[1024]; |
| u_int i, len; |
| |
| len = EVP_MD_size(md); |
| |
| if (name_from_hostfile == NULL) { |
| /* Create new salt */ |
| for (i = 0; i < len; i++) |
| salt[i] = arc4random(); |
| } else { |
| /* Extract salt from known host entry */ |
| if (extract_salt(name_from_hostfile, src_len, salt, |
| sizeof(salt)) == -1) |
| return (NULL); |
| } |
| |
| HMAC_Init(&mac_ctx, salt, len, md); |
| HMAC_Update(&mac_ctx, host, strlen(host)); |
| HMAC_Final(&mac_ctx, result, NULL); |
| HMAC_cleanup(&mac_ctx); |
| |
| if (__b64_ntop(salt, len, uu_salt, sizeof(uu_salt)) == -1 || |
| __b64_ntop(result, len, uu_result, sizeof(uu_result)) == -1) |
| fatal("host_hash: __b64_ntop failed"); |
| |
| snprintf(encoded, sizeof(encoded), "%s%s%c%s", HASH_MAGIC, uu_salt, |
| HASH_DELIM, uu_result); |
| |
| return (encoded); |
| } |
| |
| /* |
| * Parses an RSA (number of bits, e, n) or DSA key from a string. Moves the |
| * pointer over the key. Skips any whitespace at the beginning and at end. |
| */ |
| |
| int |
| hostfile_read_key(char **cpp, u_int *bitsp, Key *ret) |
| { |
| char *cp; |
| |
| /* Skip leading whitespace. */ |
| for (cp = *cpp; *cp == ' ' || *cp == '\t'; cp++) |
| ; |
| |
| if (key_read(ret, &cp) != 1) |
| return 0; |
| |
| /* Skip trailing whitespace. */ |
| for (; *cp == ' ' || *cp == '\t'; cp++) |
| ; |
| |
| /* Return results. */ |
| *cpp = cp; |
| if (bitsp != NULL) |
| *bitsp = key_size(ret); |
| return 1; |
| } |
| |
| static int |
| hostfile_check_key(int bits, const Key *key, const char *host, |
| const char *filename, u_long linenum) |
| { |
| if (key == NULL || key->type != KEY_RSA1 || key->rsa == NULL) |
| return 1; |
| if (bits != BN_num_bits(key->rsa->n)) { |
| logit("Warning: %s, line %lu: keysize mismatch for host %s: " |
| "actual %d vs. announced %d.", |
| filename, linenum, host, BN_num_bits(key->rsa->n), bits); |
| logit("Warning: replace %d with %d in %s, line %lu.", |
| bits, BN_num_bits(key->rsa->n), filename, linenum); |
| } |
| return 1; |
| } |
| |
| static HostkeyMarker |
| check_markers(char **cpp) |
| { |
| char marker[32], *sp, *cp = *cpp; |
| int ret = MRK_NONE; |
| |
| while (*cp == '@') { |
| /* Only one marker is allowed */ |
| if (ret != MRK_NONE) |
| return MRK_ERROR; |
| /* Markers are terminated by whitespace */ |
| if ((sp = strchr(cp, ' ')) == NULL && |
| (sp = strchr(cp, '\t')) == NULL) |
| return MRK_ERROR; |
| /* Extract marker for comparison */ |
| if (sp <= cp + 1 || sp >= cp + sizeof(marker)) |
| return MRK_ERROR; |
| memcpy(marker, cp, sp - cp); |
| marker[sp - cp] = '\0'; |
| if (strcmp(marker, CA_MARKER) == 0) |
| ret = MRK_CA; |
| else if (strcmp(marker, REVOKE_MARKER) == 0) |
| ret = MRK_REVOKE; |
| else |
| return MRK_ERROR; |
| |
| /* Skip past marker and any whitespace that follows it */ |
| cp = sp; |
| for (; *cp == ' ' || *cp == '\t'; cp++) |
| ; |
| } |
| *cpp = cp; |
| return ret; |
| } |
| |
| struct hostkeys * |
| init_hostkeys(void) |
| { |
| struct hostkeys *ret = xcalloc(1, sizeof(*ret)); |
| |
| ret->entries = NULL; |
| return ret; |
| } |
| |
| void |
| load_hostkeys(struct hostkeys *hostkeys, const char *host, const char *path) |
| { |
| FILE *f; |
| char line[8192]; |
| u_long linenum = 0, num_loaded = 0; |
| char *cp, *cp2, *hashed_host; |
| HostkeyMarker marker; |
| Key *key; |
| int kbits; |
| |
| if ((f = fopen(path, "r")) == NULL) |
| return; |
| debug3("%s: loading entries for host \"%.100s\" from file \"%s\"", |
| __func__, host, path); |
| while (read_keyfile_line(f, path, line, sizeof(line), &linenum) == 0) { |
| cp = line; |
| |
| /* Skip any leading whitespace, comments and empty lines. */ |
| for (; *cp == ' ' || *cp == '\t'; cp++) |
| ; |
| if (!*cp || *cp == '#' || *cp == '\n') |
| continue; |
| |
| if ((marker = check_markers(&cp)) == MRK_ERROR) { |
| verbose("%s: invalid marker at %s:%lu", |
| __func__, path, linenum); |
| continue; |
| } |
| |
| /* Find the end of the host name portion. */ |
| for (cp2 = cp; *cp2 && *cp2 != ' ' && *cp2 != '\t'; cp2++) |
| ; |
| |
| /* Check if the host name matches. */ |
| if (match_hostname(host, cp, (u_int) (cp2 - cp)) != 1) { |
| if (*cp != HASH_DELIM) |
| continue; |
| hashed_host = host_hash(host, cp, (u_int) (cp2 - cp)); |
| if (hashed_host == NULL) { |
| debug("Invalid hashed host line %lu of %s", |
| linenum, path); |
| continue; |
| } |
| if (strncmp(hashed_host, cp, (u_int) (cp2 - cp)) != 0) |
| continue; |
| } |
| |
| /* Got a match. Skip host name. */ |
| cp = cp2; |
| |
| /* |
| * Extract the key from the line. This will skip any leading |
| * whitespace. Ignore badly formatted lines. |
| */ |
| key = key_new(KEY_UNSPEC); |
| if (!hostfile_read_key(&cp, &kbits, key)) { |
| key_free(key); |
| key = key_new(KEY_RSA1); |
| if (!hostfile_read_key(&cp, &kbits, key)) { |
| key_free(key); |
| continue; |
| } |
| } |
| if (!hostfile_check_key(kbits, key, host, path, linenum)) |
| continue; |
| |
| debug3("%s: found %skey type %s in file %s:%lu", __func__, |
| marker == MRK_NONE ? "" : |
| (marker == MRK_CA ? "ca " : "revoked "), |
| key_type(key), path, linenum); |
| hostkeys->entries = xrealloc(hostkeys->entries, |
| hostkeys->num_entries + 1, sizeof(*hostkeys->entries)); |
| hostkeys->entries[hostkeys->num_entries].host = xstrdup(host); |
| hostkeys->entries[hostkeys->num_entries].file = xstrdup(path); |
| hostkeys->entries[hostkeys->num_entries].line = linenum; |
| hostkeys->entries[hostkeys->num_entries].key = key; |
| hostkeys->entries[hostkeys->num_entries].marker = marker; |
| hostkeys->num_entries++; |
| num_loaded++; |
| } |
| debug3("%s: loaded %lu keys", __func__, num_loaded); |
| return; |
| } |
| |
| void |
| free_hostkeys(struct hostkeys *hostkeys) |
| { |
| u_int i; |
| |
| for (i = 0; i < hostkeys->num_entries; i++) { |
| xfree(hostkeys->entries[i].host); |
| xfree(hostkeys->entries[i].file); |
| key_free(hostkeys->entries[i].key); |
| bzero(hostkeys->entries + i, sizeof(*hostkeys->entries)); |
| } |
| if (hostkeys->entries != NULL) |
| xfree(hostkeys->entries); |
| hostkeys->entries = NULL; |
| hostkeys->num_entries = 0; |
| xfree(hostkeys); |
| } |
| |
| static int |
| check_key_not_revoked(struct hostkeys *hostkeys, Key *k) |
| { |
| int is_cert = key_is_cert(k); |
| u_int i; |
| |
| for (i = 0; i < hostkeys->num_entries; i++) { |
| if (hostkeys->entries[i].marker != MRK_REVOKE) |
| continue; |
| if (key_equal_public(k, hostkeys->entries[i].key)) |
| return -1; |
| if (is_cert && |
| key_equal_public(k->cert->signature_key, |
| hostkeys->entries[i].key)) |
| return -1; |
| } |
| return 0; |
| } |
| |
| /* |
| * Match keys against a specified key, or look one up by key type. |
| * |
| * If looking for a keytype (key == NULL) and one is found then return |
| * HOST_FOUND, otherwise HOST_NEW. |
| * |
| * If looking for a key (key != NULL): |
| * 1. If the key is a cert and a matching CA is found, return HOST_OK |
| * 2. If the key is not a cert and a matching key is found, return HOST_OK |
| * 3. If no key matches but a key with a different type is found, then |
| * return HOST_CHANGED |
| * 4. If no matching keys are found, then return HOST_NEW. |
| * |
| * Finally, check any found key is not revoked. |
| */ |
| static HostStatus |
| check_hostkeys_by_key_or_type(struct hostkeys *hostkeys, |
| Key *k, int keytype, const struct hostkey_entry **found) |
| { |
| u_int i; |
| HostStatus end_return = HOST_NEW; |
| int want_cert = key_is_cert(k); |
| HostkeyMarker want_marker = want_cert ? MRK_CA : MRK_NONE; |
| int proto = (k ? k->type : keytype) == KEY_RSA1 ? 1 : 2; |
| |
| if (found != NULL) |
| *found = NULL; |
| |
| for (i = 0; i < hostkeys->num_entries; i++) { |
| if (proto == 1 && hostkeys->entries[i].key->type != KEY_RSA1) |
| continue; |
| if (proto == 2 && hostkeys->entries[i].key->type == KEY_RSA1) |
| continue; |
| if (hostkeys->entries[i].marker != want_marker) |
| continue; |
| if (k == NULL) { |
| if (hostkeys->entries[i].key->type != keytype) |
| continue; |
| end_return = HOST_FOUND; |
| if (found != NULL) |
| *found = hostkeys->entries + i; |
| k = hostkeys->entries[i].key; |
| break; |
| } |
| if (want_cert) { |
| if (key_equal_public(k->cert->signature_key, |
| hostkeys->entries[i].key)) { |
| /* A matching CA exists */ |
| end_return = HOST_OK; |
| if (found != NULL) |
| *found = hostkeys->entries + i; |
| break; |
| } |
| } else { |
| if (key_equal(k, hostkeys->entries[i].key)) { |
| end_return = HOST_OK; |
| if (found != NULL) |
| *found = hostkeys->entries + i; |
| break; |
| } |
| /* A non-maching key exists */ |
| end_return = HOST_CHANGED; |
| if (found != NULL) |
| *found = hostkeys->entries + i; |
| } |
| } |
| if (check_key_not_revoked(hostkeys, k) != 0) { |
| end_return = HOST_REVOKED; |
| if (found != NULL) |
| *found = NULL; |
| } |
| return end_return; |
| } |
| |
| HostStatus |
| check_key_in_hostkeys(struct hostkeys *hostkeys, Key *key, |
| const struct hostkey_entry **found) |
| { |
| if (key == NULL) |
| fatal("no key to look up"); |
| return check_hostkeys_by_key_or_type(hostkeys, key, 0, found); |
| } |
| |
| int |
| lookup_key_in_hostkeys_by_type(struct hostkeys *hostkeys, int keytype, |
| const struct hostkey_entry **found) |
| { |
| return (check_hostkeys_by_key_or_type(hostkeys, NULL, keytype, |
| found) == HOST_FOUND); |
| } |
| |
| /* |
| * Appends an entry to the host file. Returns false if the entry could not |
| * be appended. |
| */ |
| |
| int |
| add_host_to_hostfile(const char *filename, const char *host, const Key *key, |
| int store_hash) |
| { |
| FILE *f; |
| int success = 0; |
| char *hashed_host = NULL; |
| |
| if (key == NULL) |
| return 1; /* XXX ? */ |
| f = fopen(filename, "a"); |
| if (!f) |
| return 0; |
| |
| if (store_hash) { |
| if ((hashed_host = host_hash(host, NULL, 0)) == NULL) { |
| error("add_host_to_hostfile: host_hash failed"); |
| fclose(f); |
| return 0; |
| } |
| } |
| fprintf(f, "%s ", store_hash ? hashed_host : host); |
| |
| if (key_write(key, f)) { |
| success = 1; |
| } else { |
| error("add_host_to_hostfile: saving key in %s failed", filename); |
| } |
| fprintf(f, "\n"); |
| fclose(f); |
| return success; |
| } |