X-Git-Url: http://andersk.mit.edu/gitweb/openssh.git/blobdiff_plain/4d19544715ea43252fa1dc6ddfbfd8979506968f..ca24b5507e1129858ef7c87a4549f0e44237a7b1:/hostfile.c diff --git a/hostfile.c b/hostfile.c index 04e9a355..cd28bf44 100644 --- a/hostfile.c +++ b/hostfile.c @@ -1,294 +1,353 @@ +/* $OpenBSD: hostfile.c,v 1.46 2009/10/11 23:03:15 djm Exp $ */ /* + * Author: Tatu Ylonen + * Copyright (c) 1995 Tatu Ylonen , 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. + */ -hostfile.c +#include "includes.h" -Author: Tatu Ylonen +#include -Copyright (c) 1995 Tatu Ylonen , Espoo, Finland - All rights reserved +#include -Created: Thu Jun 29 07:10:56 1995 ylo +#include +#include -Functions for manipulating the known hosts files. +#include +#include +#include +#include +#include -*/ +#include "xmalloc.h" +#include "match.h" +#include "key.h" +#include "hostfile.h" +#include "log.h" -#include "includes.h" -RCSID("$Id$"); +static int +extract_salt(const char *s, u_int l, char *salt, size_t salt_len) +{ + char *p, *b64salt; + u_int b64len; + int ret; -#include "packet.h" -#include "ssh.h" + 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); + } -/* Reads a multiple-precision integer in hex from the buffer, and advances the - pointer. The integer must already be initialized. This function is - permitted to modify the buffer. This leaves *cpp to point just beyond - the last processed (and maybe modified) character. Note that this may - modify the buffer containing the number. */ + 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); + } -int -auth_rsa_read_bignum(char **cpp, BIGNUM *value) + return (0); +} + +char * +host_hash(const char *host, const char *name_from_hostfile, u_int src_len) { - char *cp = *cpp; - int len, old; + 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); + } - /* Skip any leading whitespace. */ - for (; *cp == ' ' || *cp == '\t'; cp++) - ; + HMAC_Init(&mac_ctx, salt, len, md); + HMAC_Update(&mac_ctx, host, strlen(host)); + HMAC_Final(&mac_ctx, result, NULL); + HMAC_cleanup(&mac_ctx); - /* Check that it begins with a hex digit. */ - if (*cp < '0' || *cp > '9') - return 0; + 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"); - /* Save starting position. */ - *cpp = cp; + snprintf(encoded, sizeof(encoded), "%s%s%c%s", HASH_MAGIC, uu_salt, + HASH_DELIM, uu_result); - /* Move forward until all hex digits skipped. */ - for (; *cp >= '0' && *cp <= '9'; cp++) - ; + 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. + */ - /* Compute the length of the hex number. */ - len = cp - *cpp; +int +hostfile_read_key(char **cpp, u_int *bitsp, Key *ret) +{ + char *cp; - /* Save the old terminating character, and replace it by \0. */ - old = *cp; - *cp = 0; + /* Skip leading whitespace. */ + for (cp = *cpp; *cp == ' ' || *cp == '\t'; cp++) + ; - - /* Parse the number. */ - if (BN_dec2bn(&value, *cpp) == 0) - return 0; + if (key_read(ret, &cp) != 1) + return 0; - /* Restore old terminating character. */ - *cp = old; + /* Skip trailing whitespace. */ + for (; *cp == ' ' || *cp == '\t'; cp++) + ; - /* Move beyond the number and return success. */ - *cpp = cp; - return 1; + /* Return results. */ + *cpp = cp; + *bitsp = key_size(ret); + return 1; } -/* Parses an RSA key (number of bits, e, n) from a string. Moves the pointer - over the key. Skips any whitespace at the beginning and at end. */ - -int -auth_rsa_read_key(char **cpp, unsigned int *bitsp, BIGNUM *e, BIGNUM *n) +static int +hostfile_check_key(int bits, const Key *key, const char *host, const char *filename, int linenum) { - unsigned int bits; - char *cp; - - /* Skip leading whitespace. */ - for (cp = *cpp; *cp == ' ' || *cp == '\t'; cp++) - ; - - /* Get number of bits. */ - if (*cp < '0' || *cp > '9') - return 0; /* Bad bit count... */ - for (bits = 0; *cp >= '0' && *cp <= '9'; cp++) - bits = 10 * bits + *cp - '0'; - - /* Get public exponent. */ - if (!auth_rsa_read_bignum(&cp, e)) - return 0; - - /* Get public modulus. */ - if (!auth_rsa_read_bignum(&cp, n)) - return 0; - - /* Skip trailing whitespace. */ - for (; *cp == ' ' || *cp == '\t'; cp++) - ; - - /* Return results. */ - *cpp = cp; - *bitsp = bits; - return 1; + if (key == NULL || key->type != KEY_RSA1 || key->rsa == NULL) + return 1; + if (bits != BN_num_bits(key->rsa->n)) { + logit("Warning: %s, line %d: 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 %d.", + bits, BN_num_bits(key->rsa->n), filename, linenum); + } + return 1; } -/* Tries to match the host name (which must be in all lowercase) against the - comma-separated sequence of subpatterns (each possibly preceded by ! to - indicate negation). Returns true if there is a positive match; zero - otherwise. */ - -int -match_hostname(const char *host, const char *pattern, unsigned int len) +/* + * Checks whether the given host (which must be in all lowercase) is already + * in the list of our known hosts. Returns HOST_OK if the host is known and + * has the specified key, HOST_NEW if the host is not known, and HOST_CHANGED + * if the host is known but used to have a different host key. + * + * If no 'key' has been specified and a key of type 'keytype' is known + * for the specified host, then HOST_FOUND is returned. + */ + +static HostStatus +check_host_in_hostfile_by_key_or_type(const char *filename, + const char *host, const Key *key, int keytype, Key *found, int *numret) { - char sub[1024]; - int negated; - int got_positive; - unsigned int i, subi; - - got_positive = 0; - for (i = 0; i < len;) - { - /* Check if the subpattern is negated. */ - if (pattern[i] == '!') - { - negated = 1; - i++; + FILE *f; + char line[8192]; + int linenum = 0; + u_int kbits; + char *cp, *cp2, *hashed_host; + HostStatus end_return; + + debug3("check_host_in_hostfile: host %s filename %s", host, filename); + + /* Open the file containing the list of known hosts. */ + f = fopen(filename, "r"); + if (!f) + return HOST_NEW; + + /* + * Return value when the loop terminates. This is set to + * HOST_CHANGED if we have seen a different key for the host and have + * not found the proper one. + */ + end_return = HOST_NEW; + + /* Go through the file. */ + while (fgets(line, sizeof(line), f)) { + cp = line; + linenum++; + + /* Skip any leading whitespace, comments and empty lines. */ + for (; *cp == ' ' || *cp == '\t'; cp++) + ; + if (!*cp || *cp == '#' || *cp == '\n') + 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 %d of %s", + linenum, filename); + 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. + */ + if (!hostfile_read_key(&cp, &kbits, found)) + continue; + + if (numret != NULL) + *numret = linenum; + + if (key == NULL) { + /* we found a key of the requested type */ + if (found->type == keytype) { + fclose(f); + return HOST_FOUND; + } + continue; + } + + if (!hostfile_check_key(kbits, found, host, filename, linenum)) + continue; + + /* Check if the current key is the same as the given key. */ + if (key_equal(key, found)) { + /* Ok, they match. */ + debug3("check_host_in_hostfile: match line %d", linenum); + fclose(f); + return HOST_OK; + } + /* + * They do not match. We will continue to go through the + * file; however, we note that we will not return that it is + * new. + */ + end_return = HOST_CHANGED; } - else - negated = 0; - - /* Extract the subpattern up to a comma or end. Convert the subpattern - to lowercase. */ - for (subi = 0; - i < len && subi < sizeof(sub) - 1 && pattern[i] != ','; - subi++, i++) - sub[subi] = isupper(pattern[i]) ? tolower(pattern[i]) : pattern[i]; - /* If subpattern too long, return failure (no match). */ - if (subi >= sizeof(sub) - 1) - return 0; - - /* If the subpattern was terminated by a comma, skip the comma. */ - if (i < len && pattern[i] == ',') - i++; - - /* Null-terminate the subpattern. */ - sub[subi] = '\0'; - - /* Try to match the subpattern against the host name. */ - if (match_pattern(host, sub)) { - if (negated) - return 0; /* Fail if host matches any negated subpattern. */ - else - got_positive = 1; - } - } - - /* Return success if got a positive match. If there was a negative match, - we have already returned zero and never get here. */ - return got_positive; + /* Clear variables and close the file. */ + fclose(f); + + /* + * Return either HOST_NEW or HOST_CHANGED, depending on whether we + * saw a different key for the host. + */ + return end_return; } -/* Checks whether the given host (which must be in all lowercase) is - already in the list of our known hosts. - Returns HOST_OK if the host is known and has the specified key, - HOST_NEW if the host is not known, and HOST_CHANGED if the host is known - but used to have a different host key. */ - HostStatus -check_host_in_hostfile(const char *filename, const char *host, - BIGNUM *e, BIGNUM *n, BIGNUM *ke, BIGNUM *kn) +check_host_in_hostfile(const char *filename, const char *host, const Key *key, + Key *found, int *numret) { - FILE *f; - char line[8192]; - int linenum = 0; - unsigned int bits, kbits, hostlen; - char *cp, *cp2; - HostStatus end_return; - - /* Open the file containing the list of known hosts. */ - f = fopen(filename, "r"); - if (!f) - return HOST_NEW; - - /* Cache the length of the host name. */ - hostlen = strlen(host); - - /* Return value when the loop terminates. This is set to HOST_CHANGED if - we have seen a different key for the host and have not found the proper - one. */ - end_return = HOST_NEW; - - /* size of modulus 'n' */ - bits = BN_num_bits(n); - - /* Go trough the file. */ - while (fgets(line, sizeof(line), f)) - { - cp = line; - linenum++; - - /* Skip any leading whitespace. */ - for (; *cp == ' ' || *cp == '\t'; cp++) - ; - - /* Ignore comment lines and empty lines. */ - if (!*cp || *cp == '#' || *cp == '\n') - 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, (unsigned int)(cp2 - cp))) - 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. */ - if (!auth_rsa_read_key(&cp, &kbits, ke, kn)) - continue; - - if (kbits != BN_num_bits(kn)) { - error("Warning: error in %s, line %d: keysize mismatch for host %s: " - "actual size %d vs. announced %d.", - filename, linenum, host, BN_num_bits(kn), kbits); - error("Warning: replace %d with %d in %s, line %d.", - kbits, BN_num_bits(kn), filename, linenum); - } - - /* Check if the current key is the same as the given key. */ - if (kbits == bits && BN_cmp(ke, e) == 0 && BN_cmp(kn, n) == 0) - { - /* Ok, they match. */ - fclose(f); - return HOST_OK; - } - - /* They do not match. We will continue to go through the file; however, - we note that we will not return that it is new. */ - end_return = HOST_CHANGED; - } - /* Clear variables and close the file. */ - fclose(f); - - /* Return either HOST_NEW or HOST_CHANGED, depending on whether we saw a - different key for the host. */ - return end_return; + if (key == NULL) + fatal("no key to look up"); + return (check_host_in_hostfile_by_key_or_type(filename, host, key, 0, + found, numret)); } -/* Appends an entry to the host file. Returns false if the entry - could not be appended. */ +int +lookup_key_in_hostfile_by_type(const char *filename, const char *host, + int keytype, Key *found, int *numret) +{ + return (check_host_in_hostfile_by_key_or_type(filename, host, NULL, + keytype, found, numret) == 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, - BIGNUM *e, BIGNUM *n) +add_host_to_hostfile(const char *filename, const char *host, const Key *key, + int store_hash) { - FILE *f; - char *buf; - unsigned int bits; - - /* Open the file for appending. */ - f = fopen(filename, "a"); - if (!f) - return 0; - - /* size of modulus 'n' */ - bits = BN_num_bits(n); - - /* Print the host name and key to the file. */ - fprintf(f, "%s %u ", host, bits); - buf = BN_bn2dec(e); - if (buf == NULL) { - error("add_host_to_hostfile: BN_bn2dec(e) failed"); - fclose(f); - return 0; - } - fprintf(f, "%s ", buf); - free (buf); - buf = BN_bn2dec(n); - if (buf == NULL) { - error("add_host_to_hostfile: BN_bn2dec(n) failed"); - fclose(f); - return 0; - } - fprintf(f, "%s\n", buf); - free (buf); - - /* Close the file. */ - fclose(f); - return 1; + 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; }