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authorAndreas Schneider <asn@cynapses.org>2010-09-28 19:08:32 +0200
committerAndreas Schneider <asn@cynapses.org>2010-09-28 19:09:29 +0200
commitb391a7603a900a04039f4a9e63c5a93ecc2c2e6a (patch)
tree4eb6675c77aa00e96da52003d9bc138790a82aee /src/keyfiles.c
parent45b551d4f7abe8f110b3ffc69789a1958986c6b7 (diff)
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pki: Create a file for known_hosts functions.
Diffstat (limited to 'src/keyfiles.c')
-rw-r--r--src/keyfiles.c673
1 files changed, 0 insertions, 673 deletions
diff --git a/src/keyfiles.c b/src/keyfiles.c
index ca84b819..c0b61171 100644
--- a/src/keyfiles.c
+++ b/src/keyfiles.c
@@ -24,7 +24,6 @@
#include "config.h"
-#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/stat.h>
@@ -1226,678 +1225,6 @@ error:
return pubkey;
}
-static int alldigits(const char *s) {
- while (*s) {
- if (isdigit(*s)) {
- s++;
- } else {
- return 0;
- }
- }
-
- return 1;
-}
-
-/** @} */
-
-
-/**
- * @addtogroup libssh_session
- *
- * @{
- */
-
-/**
- * @internal
- *
- * @brief Free a token array.
- */
-static void tokens_free(char **tokens) {
- if (tokens == NULL) {
- return;
- }
-
- SAFE_FREE(tokens[0]);
- /* It's not needed to free other pointers because tokens generated by
- * space_tokenize fit all in one malloc
- */
- SAFE_FREE(tokens);
-}
-
-/**
- * @internal
- *
- * @brief Return one line of known host file.
- *
- * This will return a token array containing (host|ip), keytype and key.
- *
- * @param[out] file A pointer to the known host file. Could be pointing to
- * NULL at start.
- *
- * @param[in] filename The file name of the known host file.
- *
- * @param[out] found_type A pointer to a string to be set with the found key
- * type.
- *
- * @returns The found_type type of key (ie "dsa","ssh-rsa1"). Don't
- * free that value. NULL if no match was found or the file
- * was not found.
- */
-static char **ssh_get_knownhost_line(ssh_session session, FILE **file,
- const char *filename, const char **found_type) {
- char buffer[4096] = {0};
- char *ptr;
- char **tokens;
-
- enter_function();
-
- if(*file == NULL){
- *file = fopen(filename,"r");
- if (*file == NULL) {
- leave_function();
- return NULL;
- }
- }
-
- while (fgets(buffer, sizeof(buffer), *file)) {
- ptr = strchr(buffer, '\n');
- if (ptr) {
- *ptr = '\0';
- }
-
- ptr = strchr(buffer,'\r');
- if (ptr) {
- *ptr = '\0';
- }
-
- if (!buffer[0] || buffer[0] == '#') {
- continue; /* skip empty lines */
- }
-
- tokens = space_tokenize(buffer);
- if (tokens == NULL) {
- fclose(*file);
- *file = NULL;
- leave_function();
- return NULL;
- }
-
- if(!tokens[0] || !tokens[1] || !tokens[2]) {
- /* it should have at least 3 tokens */
- tokens_free(tokens);
- continue;
- }
-
- *found_type = tokens[1];
- if (tokens[3]) {
- /* openssh rsa1 format has 4 tokens on the line. Recognize it
- by the fact that everything is all digits */
- if (tokens[4]) {
- /* that's never valid */
- tokens_free(tokens);
- continue;
- }
- if (alldigits(tokens[1]) && alldigits(tokens[2]) && alldigits(tokens[3])) {
- *found_type = "ssh-rsa1";
- } else {
- /* 3 tokens only, not four */
- tokens_free(tokens);
- continue;
- }
- }
- leave_function();
- return tokens;
- }
-
- fclose(*file);
- *file = NULL;
-
- /* we did not find anything, end of file*/
- leave_function();
- return NULL;
-}
-
-/**
- * @brief Check the public key in the known host line matches the public key of
- * the currently connected server.
- *
- * @param[in] session The SSH session to use.
- *
- * @param[in] tokens A list of tokens in the known_hosts line.
- *
- * @returns 1 if the key matches, 0 if the key doesn't match and -1
- * on error.
- */
-static int check_public_key(ssh_session session, char **tokens) {
- ssh_string pubkey = session->current_crypto->server_pubkey;
- ssh_buffer pubkey_buffer;
- char *pubkey_64;
-
- /* ok we found some public key in known hosts file. now un-base64it */
- if (alldigits(tokens[1])) {
- /* openssh rsa1 format */
- bignum tmpbn;
- ssh_string tmpstring;
- unsigned int len;
- int i;
-
- pubkey_buffer = ssh_buffer_new();
- if (pubkey_buffer == NULL) {
- return -1;
- }
-
- tmpstring = ssh_string_from_char("ssh-rsa1");
- if (tmpstring == NULL) {
- ssh_buffer_free(pubkey_buffer);
- return -1;
- }
-
- if (buffer_add_ssh_string(pubkey_buffer, tmpstring) < 0) {
- ssh_buffer_free(pubkey_buffer);
- ssh_string_free(tmpstring);
- return -1;
- }
- ssh_string_free(tmpstring);
-
- for (i = 2; i < 4; i++) { /* e, then n */
- tmpbn = NULL;
- bignum_dec2bn(tokens[i], &tmpbn);
- if (tmpbn == NULL) {
- ssh_buffer_free(pubkey_buffer);
- return -1;
- }
- /* for some reason, make_bignum_string does not work
- because of the padding which it does --kv */
- /* tmpstring = make_bignum_string(tmpbn); */
- /* do it manually instead */
- len = bignum_num_bytes(tmpbn);
- tmpstring = malloc(4 + len);
- if (tmpstring == NULL) {
- ssh_buffer_free(pubkey_buffer);
- bignum_free(tmpbn);
- return -1;
- }
- /* TODO: fix the hardcoding */
- tmpstring->size = htonl(len);
-#ifdef HAVE_LIBGCRYPT
- bignum_bn2bin(tmpbn, len, tmpstring->string);
-#elif defined HAVE_LIBCRYPTO
- bignum_bn2bin(tmpbn, tmpstring->string);
-#endif
- bignum_free(tmpbn);
- if (buffer_add_ssh_string(pubkey_buffer, tmpstring) < 0) {
- ssh_buffer_free(pubkey_buffer);
- ssh_string_free(tmpstring);
- bignum_free(tmpbn);
- return -1;
- }
- ssh_string_free(tmpstring);
- }
- } else {
- /* ssh-dss or ssh-rsa */
- pubkey_64 = tokens[2];
- pubkey_buffer = base64_to_bin(pubkey_64);
- }
-
- if (pubkey_buffer == NULL) {
- ssh_set_error(session, SSH_FATAL,
- "Verifying that server is a known host: base64 error");
- return -1;
- }
-
- if (ssh_buffer_get_len(pubkey_buffer) != ssh_string_len(pubkey)) {
- ssh_buffer_free(pubkey_buffer);
- return 0;
- }
-
- /* now test that they are identical */
- if (memcmp(ssh_buffer_get_begin(pubkey_buffer), pubkey->string,
- ssh_buffer_get_len(pubkey_buffer)) != 0) {
- ssh_buffer_free(pubkey_buffer);
- return 0;
- }
-
- ssh_buffer_free(pubkey_buffer);
- return 1;
-}
-
-/**
- * @brief Check if a hostname matches a openssh-style hashed known host.
- *
- * @param[in] host The host to check.
- *
- * @param[in] hashed The hashed value.
- *
- * @returns 1 if it matches, 0 otherwise.
- */
-static int match_hashed_host(ssh_session session, const char *host,
- const char *sourcehash) {
- /* Openssh hash structure :
- * |1|base64 encoded salt|base64 encoded hash
- * hash is produced that way :
- * hash := HMAC_SHA1(key=salt,data=host)
- */
- unsigned char buffer[256] = {0};
- ssh_buffer salt;
- ssh_buffer hash;
- HMACCTX mac;
- char *source;
- char *b64hash;
- int match;
- unsigned int size;
-
- enter_function();
-
- if (strncmp(sourcehash, "|1|", 3) != 0) {
- leave_function();
- return 0;
- }
-
- source = strdup(sourcehash + 3);
- if (source == NULL) {
- leave_function();
- return 0;
- }
-
- b64hash = strchr(source, '|');
- if (b64hash == NULL) {
- /* Invalid hash */
- SAFE_FREE(source);
- leave_function();
- return 0;
- }
-
- *b64hash = '\0';
- b64hash++;
-
- salt = base64_to_bin(source);
- if (salt == NULL) {
- SAFE_FREE(source);
- leave_function();
- return 0;
- }
-
- hash = base64_to_bin(b64hash);
- SAFE_FREE(source);
- if (hash == NULL) {
- ssh_buffer_free(salt);
- leave_function();
- return 0;
- }
-
- mac = hmac_init(ssh_buffer_get_begin(salt), ssh_buffer_get_len(salt), HMAC_SHA1);
- if (mac == NULL) {
- ssh_buffer_free(salt);
- ssh_buffer_free(hash);
- leave_function();
- return 0;
- }
- size = sizeof(buffer);
- hmac_update(mac, host, strlen(host));
- hmac_final(mac, buffer, &size);
-
- if (size == ssh_buffer_get_len(hash) &&
- memcmp(buffer, ssh_buffer_get_begin(hash), size) == 0) {
- match = 1;
- } else {
- match = 0;
- }
-
- ssh_buffer_free(salt);
- ssh_buffer_free(hash);
-
- ssh_log(session, SSH_LOG_PACKET,
- "Matching a hashed host: %s match=%d", host, match);
-
- leave_function();
- return match;
-}
-
-/* How it's working :
- * 1- we open the known host file and bitch if it doesn't exist
- * 2- we need to examine each line of the file, until going on state SSH_SERVER_KNOWN_OK:
- * - there's a match. if the key is good, state is SSH_SERVER_KNOWN_OK,
- * else it's SSH_SERVER_KNOWN_CHANGED (or SSH_SERVER_FOUND_OTHER)
- * - there's no match : no change
- */
-
-/**
- * @brief Check if the server is known.
- *
- * Checks the user's known host file for a previous connection to the
- * current server.
- *
- * @param[in] session The SSH session to use.
- *
- * @returns SSH_SERVER_KNOWN_OK: The server is known and has not changed.\n
- * SSH_SERVER_KNOWN_CHANGED: The server key has changed. Either you
- * are under attack or the administrator
- * changed the key. You HAVE to warn the
- * user about a possible attack.\n
- * SSH_SERVER_FOUND_OTHER: The server gave use a key of a type while
- * we had an other type recorded. It is a
- * possible attack.\n
- * SSH_SERVER_NOT_KNOWN: The server is unknown. User should
- * confirm the MD5 is correct.\n
- * SSH_SERVER_FILE_NOT_FOUND: The known host file does not exist. The
- * host is thus unknown. File will be
- * created if host key is accepted.\n
- * SSH_SERVER_ERROR: Some error happened.
- *
- * @see ssh_get_pubkey_hash()
- *
- * @bug There is no current way to remove or modify an entry into the known
- * host table.
- */
-int ssh_is_server_known(ssh_session session) {
- FILE *file = NULL;
- char **tokens;
- char *host;
- char *hostport;
- const char *type;
- int match;
- int ret = SSH_SERVER_NOT_KNOWN;
-
- enter_function();
-
- if (session->knownhosts == NULL) {
- if (ssh_options_apply(session) < 0) {
- ssh_set_error(session, SSH_REQUEST_DENIED,
- "Can't find a known_hosts file");
- leave_function();
- return SSH_SERVER_FILE_NOT_FOUND;
- }
- }
-
- if (session->host == NULL) {
- ssh_set_error(session, SSH_FATAL,
- "Can't verify host in known hosts if the hostname isn't known");
- leave_function();
- return SSH_SERVER_ERROR;
- }
-
- if (session->current_crypto == NULL){
- ssh_set_error(session, SSH_FATAL,
- "ssh_is_host_known called without cryptographic context");
- leave_function();
- return SSH_SERVER_ERROR;
- }
- host = ssh_lowercase(session->host);
- hostport = ssh_hostport(host,session->port);
- if (host == NULL || hostport == NULL) {
- ssh_set_error_oom(session);
- SAFE_FREE(host);
- SAFE_FREE(hostport);
- leave_function();
- return SSH_SERVER_ERROR;
- }
-
- do {
- tokens = ssh_get_knownhost_line(session, &file,
- session->knownhosts, &type);
-
- /* End of file, return the current state */
- if (tokens == NULL) {
- break;
- }
- match = match_hashed_host(session, host, tokens[0]);
- if (match == 0){
- match = match_hostname(hostport, tokens[0], strlen(tokens[0]));
- }
- if (match == 0) {
- match = match_hostname(host, tokens[0], strlen(tokens[0]));
- }
- if (match == 0) {
- match = match_hashed_host(session, hostport, tokens[0]);
- }
- if (match) {
- /* We got a match. Now check the key type */
- if (strcmp(session->current_crypto->server_pubkey_type, type) != 0) {
- /* Different type. We don't override the known_changed error which is
- * more important */
- if (ret != SSH_SERVER_KNOWN_CHANGED)
- ret = SSH_SERVER_FOUND_OTHER;
- tokens_free(tokens);
- continue;
- }
- /* so we know the key type is good. We may get a good key or a bad key. */
- match = check_public_key(session, tokens);
- tokens_free(tokens);
-
- if (match < 0) {
- ret = SSH_SERVER_ERROR;
- break;
- } else if (match == 1) {
- ret = SSH_SERVER_KNOWN_OK;
- break;
- } else if(match == 0) {
- /* We override the status with the wrong key state */
- ret = SSH_SERVER_KNOWN_CHANGED;
- }
- } else {
- tokens_free(tokens);
- }
- } while (1);
-
- if ( (ret == SSH_SERVER_NOT_KNOWN) && (session->StrictHostKeyChecking == 0) ) {
- ssh_write_knownhost(session);
- ret = SSH_SERVER_KNOWN_OK;
- }
-
- SAFE_FREE(host);
- SAFE_FREE(hostport);
- if (file != NULL) {
- fclose(file);
- }
-
- /* Return the current state at end of file */
- leave_function();
- return ret;
-}
-
-/**
- * @brief Write the current server as known in the known hosts file.
- *
- * This will create the known hosts file if it does not exist. You generaly use
- * it when ssh_is_server_known() answered SSH_SERVER_NOT_KNOWN.
- *
- * @param[in] session The ssh session to use.
- *
- * @return SSH_OK on success, SSH_ERROR on error.
- */
-int ssh_write_knownhost(ssh_session session) {
- ssh_string pubkey;
- unsigned char *pubkey_64;
- char buffer[4096] = {0};
- FILE *file;
- char *dir;
- char *host;
- char *hostport;
- size_t len = 0;
-
- if (session->host == NULL) {
- ssh_set_error(session, SSH_FATAL,
- "Can't write host in known hosts if the hostname isn't known");
- return SSH_ERROR;
- }
-
- host = ssh_lowercase(session->host);
- /* If using a nonstandard port, save the host in the [host]:port format */
- if(session->port != 22){
- hostport = ssh_hostport(host,session->port);
- SAFE_FREE(host);
- host=hostport;
- hostport=NULL;
- }
-
- if (session->knownhosts == NULL) {
- if (ssh_options_apply(session) < 0) {
- ssh_set_error(session, SSH_FATAL, "Can't find a known_hosts file");
- return SSH_ERROR;
- }
- }
-
- if(session->current_crypto==NULL) {
- ssh_set_error(session, SSH_FATAL, "No current crypto context");
- return SSH_ERROR;
- }
-
- pubkey = session->current_crypto->server_pubkey;
- if(pubkey == NULL){
- ssh_set_error(session, SSH_FATAL, "No public key present");
- return SSH_ERROR;
- }
-
- /* Check if ~/.ssh exists and create it if not */
- dir = ssh_dirname(session->knownhosts);
- if (dir == NULL) {
- ssh_set_error(session, SSH_FATAL, "%s", strerror(errno));
- return -1;
- }
- if (! ssh_file_readaccess_ok(dir)) {
- if (ssh_mkdir(dir, 0700) < 0) {
- ssh_set_error(session, SSH_FATAL,
- "Cannot create %s directory.", dir);
- SAFE_FREE(dir);
- return -1;
- }
- }
- SAFE_FREE(dir);
-
- file = fopen(session->knownhosts, "a");
- if (file == NULL) {
- ssh_set_error(session, SSH_FATAL,
- "Couldn't open known_hosts file %s for appending: %s",
- session->knownhosts, strerror(errno));
- SAFE_FREE(host);
- return -1;
- }
-
- if (strcmp(session->current_crypto->server_pubkey_type, "ssh-rsa1") == 0) {
- /* openssh uses a different format for ssh-rsa1 keys.
- Be compatible --kv */
- ssh_public_key key;
- char *e_string = NULL;
- char *n_string = NULL;
- bignum e = NULL;
- bignum n = NULL;
- int rsa_size;
-#ifdef HAVE_LIBGCRYPT
- gcry_sexp_t sexp;
-#endif
-
- key = publickey_from_string(session, pubkey);
- if (key == NULL) {
- fclose(file);
- SAFE_FREE(host);
- return -1;
- }
-
-#ifdef HAVE_LIBGCRYPT
- sexp = gcry_sexp_find_token(key->rsa_pub, "e", 0);
- if (sexp == NULL) {
- publickey_free(key);
- fclose(file);
- SAFE_FREE(host);
- return -1;
- }
- e = gcry_sexp_nth_mpi(sexp, 1, GCRYMPI_FMT_USG);
- gcry_sexp_release(sexp);
- if (e == NULL) {
- publickey_free(key);
- fclose(file);
- SAFE_FREE(host);
- return -1;
- }
-
- sexp = gcry_sexp_find_token(key->rsa_pub, "n", 0);
- if (sexp == NULL) {
- publickey_free(key);
- bignum_free(e);
- fclose(file);
- SAFE_FREE(host);
- return -1;
- }
- n = gcry_sexp_nth_mpi(sexp, 1, GCRYMPI_FMT_USG);
- gcry_sexp_release(sexp);
- if (n == NULL) {
- publickey_free(key);
- bignum_free(e);
- fclose(file);
- SAFE_FREE(host);
- return -1;
- }
-
- rsa_size = (gcry_pk_get_nbits(key->rsa_pub) + 7) / 8;
-#elif defined HAVE_LIBCRYPTO
- e = key->rsa_pub->e;
- n = key->rsa_pub->n;
- rsa_size = RSA_size(key->rsa_pub);
-#endif
-
- e_string = bignum_bn2dec(e);
- n_string = bignum_bn2dec(n);
- if (e_string == NULL || n_string == NULL) {
-#ifdef HAVE_LIBGCRYPT
- bignum_free(e);
- bignum_free(n);
- SAFE_FREE(e_string);
- SAFE_FREE(n_string);
-#elif defined HAVE_LIBCRYPTO
- OPENSSL_free(e_string);
- OPENSSL_free(n_string);
-#endif
- publickey_free(key);
- fclose(file);
- SAFE_FREE(host);
- return -1;
- }
-
- snprintf(buffer, sizeof(buffer),
- "%s %d %s %s\n",
- host,
- rsa_size << 3,
- e_string,
- n_string);
-
-#ifdef HAVE_LIBGCRYPT
- bignum_free(e);
- bignum_free(n);
- SAFE_FREE(e_string);
- SAFE_FREE(n_string);
-#elif defined HAVE_LIBCRYPTO
- OPENSSL_free(e_string);
- OPENSSL_free(n_string);
-#endif
-
- publickey_free(key);
- } else {
- pubkey_64 = bin_to_base64(pubkey->string, ssh_string_len(pubkey));
- if (pubkey_64 == NULL) {
- fclose(file);
- SAFE_FREE(host);
- return -1;
- }
-
- snprintf(buffer, sizeof(buffer),
- "%s %s %s\n",
- host,
- session->current_crypto->server_pubkey_type,
- pubkey_64);
-
- SAFE_FREE(pubkey_64);
- }
- SAFE_FREE(host);
- len = strlen(buffer);
- if (fwrite(buffer, len, 1, file) != 1 || ferror(file)) {
- fclose(file);
- return -1;
- }
-
- fclose(file);
- return 0;
-}
-
/** @} */
/* vim: set ts=4 sw=4 et cindent: */