pki: Create a file for known_hosts functions.
Этот коммит содержится в:
Andreas Schneider
родитель
45b551d4f7
Коммит
b391a7603a
@ -90,6 +90,7 @@ set(libssh_SRCS
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kex.c
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keyfiles.c
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keys.c
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known_hosts.c
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legacy.c
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libcrypto.c
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libgcrypt.c
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673
src/keyfiles.c
673
src/keyfiles.c
@ -24,7 +24,6 @@
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#include "config.h"
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#include <ctype.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <sys/stat.h>
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@ -1226,678 +1225,6 @@ error:
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return pubkey;
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}
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static int alldigits(const char *s) {
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while (*s) {
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if (isdigit(*s)) {
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s++;
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} else {
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return 0;
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}
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}
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return 1;
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}
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/** @} */
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/**
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* @addtogroup libssh_session
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*
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* @{
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*/
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/**
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* @internal
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*
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* @brief Free a token array.
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*/
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static void tokens_free(char **tokens) {
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if (tokens == NULL) {
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return;
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}
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SAFE_FREE(tokens[0]);
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/* It's not needed to free other pointers because tokens generated by
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* space_tokenize fit all in one malloc
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*/
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SAFE_FREE(tokens);
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}
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/**
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* @internal
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*
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* @brief Return one line of known host file.
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*
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* This will return a token array containing (host|ip), keytype and key.
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*
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* @param[out] file A pointer to the known host file. Could be pointing to
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* NULL at start.
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*
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* @param[in] filename The file name of the known host file.
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*
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* @param[out] found_type A pointer to a string to be set with the found key
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* type.
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*
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* @returns The found_type type of key (ie "dsa","ssh-rsa1"). Don't
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* free that value. NULL if no match was found or the file
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* was not found.
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*/
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static char **ssh_get_knownhost_line(ssh_session session, FILE **file,
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const char *filename, const char **found_type) {
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char buffer[4096] = {0};
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char *ptr;
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char **tokens;
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enter_function();
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if(*file == NULL){
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*file = fopen(filename,"r");
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if (*file == NULL) {
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leave_function();
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return NULL;
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}
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}
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while (fgets(buffer, sizeof(buffer), *file)) {
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ptr = strchr(buffer, '\n');
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if (ptr) {
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*ptr = '\0';
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}
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ptr = strchr(buffer,'\r');
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if (ptr) {
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*ptr = '\0';
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}
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if (!buffer[0] || buffer[0] == '#') {
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continue; /* skip empty lines */
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}
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tokens = space_tokenize(buffer);
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if (tokens == NULL) {
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fclose(*file);
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*file = NULL;
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leave_function();
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return NULL;
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}
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if(!tokens[0] || !tokens[1] || !tokens[2]) {
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/* it should have at least 3 tokens */
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tokens_free(tokens);
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continue;
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}
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*found_type = tokens[1];
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if (tokens[3]) {
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/* openssh rsa1 format has 4 tokens on the line. Recognize it
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by the fact that everything is all digits */
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if (tokens[4]) {
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/* that's never valid */
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tokens_free(tokens);
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continue;
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}
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if (alldigits(tokens[1]) && alldigits(tokens[2]) && alldigits(tokens[3])) {
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*found_type = "ssh-rsa1";
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} else {
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/* 3 tokens only, not four */
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tokens_free(tokens);
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continue;
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}
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}
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leave_function();
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return tokens;
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}
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fclose(*file);
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*file = NULL;
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/* we did not find anything, end of file*/
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leave_function();
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return NULL;
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}
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/**
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* @brief Check the public key in the known host line matches the public key of
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* the currently connected server.
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*
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* @param[in] session The SSH session to use.
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*
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* @param[in] tokens A list of tokens in the known_hosts line.
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*
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* @returns 1 if the key matches, 0 if the key doesn't match and -1
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* on error.
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*/
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static int check_public_key(ssh_session session, char **tokens) {
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ssh_string pubkey = session->current_crypto->server_pubkey;
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ssh_buffer pubkey_buffer;
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char *pubkey_64;
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/* ok we found some public key in known hosts file. now un-base64it */
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if (alldigits(tokens[1])) {
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/* openssh rsa1 format */
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bignum tmpbn;
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ssh_string tmpstring;
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unsigned int len;
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int i;
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pubkey_buffer = ssh_buffer_new();
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if (pubkey_buffer == NULL) {
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return -1;
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}
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tmpstring = ssh_string_from_char("ssh-rsa1");
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if (tmpstring == NULL) {
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ssh_buffer_free(pubkey_buffer);
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return -1;
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}
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if (buffer_add_ssh_string(pubkey_buffer, tmpstring) < 0) {
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ssh_buffer_free(pubkey_buffer);
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ssh_string_free(tmpstring);
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return -1;
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}
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ssh_string_free(tmpstring);
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for (i = 2; i < 4; i++) { /* e, then n */
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tmpbn = NULL;
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bignum_dec2bn(tokens[i], &tmpbn);
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if (tmpbn == NULL) {
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ssh_buffer_free(pubkey_buffer);
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return -1;
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}
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/* for some reason, make_bignum_string does not work
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because of the padding which it does --kv */
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/* tmpstring = make_bignum_string(tmpbn); */
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/* do it manually instead */
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len = bignum_num_bytes(tmpbn);
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tmpstring = malloc(4 + len);
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if (tmpstring == NULL) {
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ssh_buffer_free(pubkey_buffer);
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bignum_free(tmpbn);
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return -1;
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}
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/* TODO: fix the hardcoding */
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tmpstring->size = htonl(len);
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#ifdef HAVE_LIBGCRYPT
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bignum_bn2bin(tmpbn, len, tmpstring->string);
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#elif defined HAVE_LIBCRYPTO
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bignum_bn2bin(tmpbn, tmpstring->string);
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#endif
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bignum_free(tmpbn);
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if (buffer_add_ssh_string(pubkey_buffer, tmpstring) < 0) {
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ssh_buffer_free(pubkey_buffer);
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ssh_string_free(tmpstring);
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bignum_free(tmpbn);
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return -1;
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}
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ssh_string_free(tmpstring);
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}
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} else {
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/* ssh-dss or ssh-rsa */
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pubkey_64 = tokens[2];
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pubkey_buffer = base64_to_bin(pubkey_64);
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}
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if (pubkey_buffer == NULL) {
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ssh_set_error(session, SSH_FATAL,
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"Verifying that server is a known host: base64 error");
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return -1;
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}
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if (ssh_buffer_get_len(pubkey_buffer) != ssh_string_len(pubkey)) {
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ssh_buffer_free(pubkey_buffer);
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return 0;
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}
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/* now test that they are identical */
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if (memcmp(ssh_buffer_get_begin(pubkey_buffer), pubkey->string,
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ssh_buffer_get_len(pubkey_buffer)) != 0) {
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ssh_buffer_free(pubkey_buffer);
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return 0;
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}
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ssh_buffer_free(pubkey_buffer);
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return 1;
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}
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/**
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* @brief Check if a hostname matches a openssh-style hashed known host.
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*
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* @param[in] host The host to check.
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*
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* @param[in] hashed The hashed value.
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*
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* @returns 1 if it matches, 0 otherwise.
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*/
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static int match_hashed_host(ssh_session session, const char *host,
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const char *sourcehash) {
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/* Openssh hash structure :
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* |1|base64 encoded salt|base64 encoded hash
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* hash is produced that way :
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* hash := HMAC_SHA1(key=salt,data=host)
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*/
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unsigned char buffer[256] = {0};
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ssh_buffer salt;
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ssh_buffer hash;
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HMACCTX mac;
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char *source;
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char *b64hash;
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int match;
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unsigned int size;
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enter_function();
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if (strncmp(sourcehash, "|1|", 3) != 0) {
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leave_function();
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return 0;
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}
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source = strdup(sourcehash + 3);
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if (source == NULL) {
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leave_function();
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return 0;
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}
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b64hash = strchr(source, '|');
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if (b64hash == NULL) {
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/* Invalid hash */
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SAFE_FREE(source);
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leave_function();
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return 0;
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}
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*b64hash = '\0';
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b64hash++;
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salt = base64_to_bin(source);
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if (salt == NULL) {
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SAFE_FREE(source);
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leave_function();
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return 0;
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}
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hash = base64_to_bin(b64hash);
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SAFE_FREE(source);
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if (hash == NULL) {
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ssh_buffer_free(salt);
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leave_function();
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return 0;
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}
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mac = hmac_init(ssh_buffer_get_begin(salt), ssh_buffer_get_len(salt), HMAC_SHA1);
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if (mac == NULL) {
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ssh_buffer_free(salt);
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ssh_buffer_free(hash);
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leave_function();
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return 0;
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}
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size = sizeof(buffer);
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hmac_update(mac, host, strlen(host));
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hmac_final(mac, buffer, &size);
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if (size == ssh_buffer_get_len(hash) &&
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memcmp(buffer, ssh_buffer_get_begin(hash), size) == 0) {
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match = 1;
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} else {
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match = 0;
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}
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ssh_buffer_free(salt);
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ssh_buffer_free(hash);
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ssh_log(session, SSH_LOG_PACKET,
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"Matching a hashed host: %s match=%d", host, match);
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leave_function();
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return match;
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}
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/* How it's working :
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* 1- we open the known host file and bitch if it doesn't exist
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* 2- we need to examine each line of the file, until going on state SSH_SERVER_KNOWN_OK:
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* - there's a match. if the key is good, state is SSH_SERVER_KNOWN_OK,
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* else it's SSH_SERVER_KNOWN_CHANGED (or SSH_SERVER_FOUND_OTHER)
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* - there's no match : no change
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*/
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/**
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* @brief Check if the server is known.
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*
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* Checks the user's known host file for a previous connection to the
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* current server.
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*
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* @param[in] session The SSH session to use.
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*
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* @returns SSH_SERVER_KNOWN_OK: The server is known and has not changed.\n
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* SSH_SERVER_KNOWN_CHANGED: The server key has changed. Either you
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* are under attack or the administrator
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* changed the key. You HAVE to warn the
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* user about a possible attack.\n
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* SSH_SERVER_FOUND_OTHER: The server gave use a key of a type while
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* we had an other type recorded. It is a
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* possible attack.\n
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* SSH_SERVER_NOT_KNOWN: The server is unknown. User should
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* confirm the MD5 is correct.\n
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* SSH_SERVER_FILE_NOT_FOUND: The known host file does not exist. The
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* host is thus unknown. File will be
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* created if host key is accepted.\n
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* SSH_SERVER_ERROR: Some error happened.
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*
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* @see ssh_get_pubkey_hash()
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*
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* @bug There is no current way to remove or modify an entry into the known
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* host table.
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*/
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int ssh_is_server_known(ssh_session session) {
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FILE *file = NULL;
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char **tokens;
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char *host;
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char *hostport;
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const char *type;
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int match;
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int ret = SSH_SERVER_NOT_KNOWN;
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enter_function();
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if (session->knownhosts == NULL) {
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if (ssh_options_apply(session) < 0) {
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ssh_set_error(session, SSH_REQUEST_DENIED,
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"Can't find a known_hosts file");
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leave_function();
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return SSH_SERVER_FILE_NOT_FOUND;
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}
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}
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if (session->host == NULL) {
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ssh_set_error(session, SSH_FATAL,
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"Can't verify host in known hosts if the hostname isn't known");
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leave_function();
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return SSH_SERVER_ERROR;
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}
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if (session->current_crypto == NULL){
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ssh_set_error(session, SSH_FATAL,
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"ssh_is_host_known called without cryptographic context");
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leave_function();
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return SSH_SERVER_ERROR;
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}
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host = ssh_lowercase(session->host);
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hostport = ssh_hostport(host,session->port);
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if (host == NULL || hostport == NULL) {
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ssh_set_error_oom(session);
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SAFE_FREE(host);
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SAFE_FREE(hostport);
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leave_function();
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return SSH_SERVER_ERROR;
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}
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do {
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tokens = ssh_get_knownhost_line(session, &file,
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session->knownhosts, &type);
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/* End of file, return the current state */
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if (tokens == NULL) {
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break;
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}
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match = match_hashed_host(session, host, tokens[0]);
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if (match == 0){
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match = match_hostname(hostport, tokens[0], strlen(tokens[0]));
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}
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if (match == 0) {
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match = match_hostname(host, tokens[0], strlen(tokens[0]));
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}
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if (match == 0) {
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match = match_hashed_host(session, hostport, tokens[0]);
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}
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if (match) {
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/* We got a match. Now check the key type */
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if (strcmp(session->current_crypto->server_pubkey_type, type) != 0) {
|
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/* Different type. We don't override the known_changed error which is
|
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* more important */
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if (ret != SSH_SERVER_KNOWN_CHANGED)
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ret = SSH_SERVER_FOUND_OTHER;
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tokens_free(tokens);
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continue;
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}
|
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/* so we know the key type is good. We may get a good key or a bad key. */
|
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match = check_public_key(session, tokens);
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tokens_free(tokens);
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|
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if (match < 0) {
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ret = SSH_SERVER_ERROR;
|
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break;
|
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} else if (match == 1) {
|
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ret = SSH_SERVER_KNOWN_OK;
|
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break;
|
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} else if(match == 0) {
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/* We override the status with the wrong key state */
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ret = SSH_SERVER_KNOWN_CHANGED;
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}
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} else {
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tokens_free(tokens);
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}
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} while (1);
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|
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if ( (ret == SSH_SERVER_NOT_KNOWN) && (session->StrictHostKeyChecking == 0) ) {
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ssh_write_knownhost(session);
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ret = SSH_SERVER_KNOWN_OK;
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}
|
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|
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SAFE_FREE(host);
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SAFE_FREE(hostport);
|
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if (file != NULL) {
|
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fclose(file);
|
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}
|
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|
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/* Return the current state at end of file */
|
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leave_function();
|
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return ret;
|
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}
|
||||
|
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/**
|
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* @brief Write the current server as known in the known hosts file.
|
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*
|
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* This will create the known hosts file if it does not exist. You generaly use
|
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* it when ssh_is_server_known() answered SSH_SERVER_NOT_KNOWN.
|
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*
|
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* @param[in] session The ssh session to use.
|
||||
*
|
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* @return SSH_OK on success, SSH_ERROR on error.
|
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*/
|
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int ssh_write_knownhost(ssh_session session) {
|
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ssh_string pubkey;
|
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unsigned char *pubkey_64;
|
||||
char buffer[4096] = {0};
|
||||
FILE *file;
|
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char *dir;
|
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char *host;
|
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char *hostport;
|
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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);
|
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/* If using a nonstandard port, save the host in the [host]:port format */
|
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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: */
|
||||
|
||||
723
src/known_hosts.c
Обычный файл
723
src/known_hosts.c
Обычный файл
@ -0,0 +1,723 @@
|
||||
/*
|
||||
* keyfiles.c - private and public key handling for authentication.
|
||||
*
|
||||
* This file is part of the SSH Library
|
||||
*
|
||||
* Copyright (c) 2003-2009 by Aris Adamantiadis
|
||||
* Copyright (c) 2009 by Andreas Schneider <mail@cynapses.org>
|
||||
*
|
||||
* The SSH Library is free software; you can redistribute it and/or modify
|
||||
* it under the terms of the GNU Lesser General Public License as published by
|
||||
* the Free Software Foundation; either version 2.1 of the License, or (at your
|
||||
* option) any later version.
|
||||
*
|
||||
* The SSH Library is distributed in the hope that it will be useful, but
|
||||
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
|
||||
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
|
||||
* License for more details.
|
||||
*
|
||||
* You should have received a copy of the GNU Lesser General Public License
|
||||
* along with the SSH Library; see the file COPYING. If not, write to
|
||||
* the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
|
||||
* MA 02111-1307, USA.
|
||||
*/
|
||||
|
||||
#include "config.h"
|
||||
|
||||
#include <ctype.h>
|
||||
#include <errno.h>
|
||||
|
||||
#include "libssh/priv.h"
|
||||
#include "libssh/session.h"
|
||||
#include "libssh/buffer.h"
|
||||
#include "libssh/misc.h"
|
||||
#include "libssh/keys.h"
|
||||
|
||||
/*todo: remove this include */
|
||||
#include "libssh/string.h"
|
||||
|
||||
#ifdef HAVE_LIBGCRYPT
|
||||
#include <gcrypt.h>
|
||||
#elif defined HAVE_LIBCRYPTO
|
||||
#include <openssl/pem.h>
|
||||
#include <openssl/dsa.h>
|
||||
#include <openssl/err.h>
|
||||
#include <openssl/rsa.h>
|
||||
#endif /* HAVE_LIBCRYPTO */
|
||||
|
||||
#ifndef _WIN32
|
||||
# include <arpa/inet.h>
|
||||
#endif
|
||||
|
||||
/**
|
||||
* @addtogroup libssh_session
|
||||
*
|
||||
* @{
|
||||
*/
|
||||
|
||||
static int alldigits(const char *s) {
|
||||
while (*s) {
|
||||
if (isdigit(*s)) {
|
||||
s++;
|
||||
} else {
|
||||
return 0;
|
||||
}
|
||||
}
|
||||
|
||||
return 1;
|
||||
}
|
||||
|
||||
/**
|
||||
* @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: */
|
||||
@ -1,4 +1,5 @@
|
||||
/*
|
||||
* known_hosts.c
|
||||
* This file is part of the SSH Library
|
||||
*
|
||||
* Copyright (c) 2010 by Aris Adamantiadis
|
||||
|
||||
Загрузка…
Ссылка в новой задаче
Block a user