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/*
* ssh plugin utilities
*
* Copyright (C) 2016-2023 Milan Broz
* Copyright (C) 2020-2023 Vojtech Trefny
*
* This file 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.
*
* This file 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 this file; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <libssh/libssh.h>
#include <libssh/sftp.h>
#include <fcntl.h>
#include <libcryptsetup.h>
#include "ssh-utils.h"
#include "../lib/nls.h"
#define KEYFILE_LENGTH_MAX 8192
int sshplugin_download_password(struct crypt_device *cd, ssh_session ssh,
const char *path, char **password, size_t *password_len)
{
char *pass = NULL;
size_t pass_len;
int r;
sftp_attributes sftp_attr = NULL;
sftp_session sftp = NULL;
sftp_file file = NULL;
sftp = sftp_new(ssh);
if (!sftp) {
crypt_log(cd, CRYPT_LOG_ERROR, _("Cannot create sftp session: "));
r = SSH_FX_FAILURE;
goto out;
}
r = sftp_init(sftp);
if (r != SSH_OK) {
crypt_log(cd, CRYPT_LOG_ERROR, _("Cannot init sftp session: "));
goto out;
}
file = sftp_open(sftp, path, O_RDONLY, 0);
if (!file) {
crypt_log(cd, CRYPT_LOG_ERROR, _("Cannot open sftp session: "));
r = SSH_FX_FAILURE;
goto out;
}
sftp_attr = sftp_fstat(file);
if (!sftp_attr) {
crypt_log(cd, CRYPT_LOG_ERROR, _("Cannot stat sftp file: "));
r = SSH_FX_FAILURE;
goto out;
}
pass_len = sftp_attr->size > KEYFILE_LENGTH_MAX ? KEYFILE_LENGTH_MAX : sftp_attr->size;
pass = malloc(pass_len);
if (!pass) {
crypt_log(cd, CRYPT_LOG_ERROR, _("Not enough memory.\n"));
r = SSH_FX_FAILURE;
goto out;
}
r = sftp_read(file, pass, pass_len);
if (r < 0 || (size_t)r != pass_len) {
crypt_log(cd, CRYPT_LOG_ERROR, _("Cannot read remote key: "));
r = SSH_FX_FAILURE;
goto out;
}
*password = pass;
*password_len = pass_len;
r = SSH_OK;
out:
if (r != SSH_OK) {
crypt_log(cd, CRYPT_LOG_ERROR, ssh_get_error(ssh));
crypt_log(cd, CRYPT_LOG_ERROR, "\n");
free(pass);
}
if (sftp_attr)
sftp_attributes_free(sftp_attr);
if (file)
sftp_close(file);
if (sftp)
sftp_free(sftp);
return r == SSH_OK ? 0 : -EINVAL;
}
ssh_session sshplugin_session_init(struct crypt_device *cd, const char *host, const char *user)
{
int r, port = 22;
ssh_session ssh = ssh_new();
if (!ssh)
return NULL;
ssh_options_set(ssh, SSH_OPTIONS_HOST, host);
ssh_options_set(ssh, SSH_OPTIONS_USER, user);
ssh_options_set(ssh, SSH_OPTIONS_PORT, &port);
crypt_log(cd, CRYPT_LOG_NORMAL, "SSH token initiating ssh session.\n");
r = ssh_connect(ssh);
if (r != SSH_OK) {
crypt_log(cd, CRYPT_LOG_ERROR, _("Connection failed: "));
goto out;
}
#if HAVE_DECL_SSH_SESSION_IS_KNOWN_SERVER
r = ssh_session_is_known_server(ssh);
#else
r = ssh_is_server_known(ssh);
#endif
if (r != SSH_SERVER_KNOWN_OK) {
crypt_log(cd, CRYPT_LOG_ERROR, _("Server not known: "));
r = SSH_AUTH_ERROR;
goto out;
}
r = SSH_OK;
/* initialise list of authentication methods. yes, according to official libssh docs... */
ssh_userauth_none(ssh, NULL);
out:
if (r != SSH_OK) {
crypt_log(cd, CRYPT_LOG_ERROR, ssh_get_error(ssh));
crypt_log(cd, CRYPT_LOG_ERROR, "\n");
ssh_disconnect(ssh);
ssh_free(ssh);
ssh = NULL;
}
return ssh;
}
int sshplugin_public_key_auth(struct crypt_device *cd, ssh_session ssh, const ssh_key pkey)
{
int r;
crypt_log(cd, CRYPT_LOG_DEBUG, "Trying public key authentication method.\n");
if (!(ssh_userauth_list(ssh, NULL) & SSH_AUTH_METHOD_PUBLICKEY)) {
crypt_log(cd, CRYPT_LOG_ERROR, _("Public key auth method not allowed on host.\n"));
return SSH_AUTH_ERROR;
}
r = ssh_userauth_try_publickey(ssh, NULL, pkey);
if (r == SSH_AUTH_SUCCESS) {
crypt_log(cd, CRYPT_LOG_DEBUG, "Public key method accepted.\n");
r = ssh_userauth_publickey(ssh, NULL, pkey);
}
if (r != SSH_AUTH_SUCCESS) {
crypt_log(cd, CRYPT_LOG_ERROR, _("Public key authentication error: "));
crypt_log(cd, CRYPT_LOG_ERROR, ssh_get_error(ssh));
crypt_log(cd, CRYPT_LOG_ERROR, "\n");
}
return r;
}
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