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/* SPDX-FileCopyrightText: 2015-2023 Greenbone AG
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
/**
* @file
* @brief Implementation of SSH related API.
*/
#include "sshutils.h"
#include <glib.h> /* for g_free, g_strdup, g_strdup_printf */
#include <gnutls/gnutls.h> /* for gnutls_datum_t */
#include <gnutls/x509.h> /* for gnutls_x509_privkey_deinit, gnutls_x509_p... */
#include <libssh/libssh.h> /* for ssh_key_free, ssh_key_type, ssh_key_type_... */
#include <string.h> /* for strcmp, strlen */
#undef G_LOG_DOMAIN
/**
* @brief GLib logging domain.
*/
#define G_LOG_DOMAIN "libgvm util"
/**
* @brief Decrypts a base64 encrypted ssh private key.
*
* @param[in] pkcs8_key PKCS#8 encrypted private key.
* @param[in] passphrase Passphrase for the private key.
*
* @return Decrypted private key if success, NULL otherwise.
*/
char *
gvm_ssh_pkcs8_decrypt (const char *pkcs8_key, const char *passphrase)
{
gnutls_datum_t data;
gnutls_x509_privkey_t key;
char buffer[16 * 2048];
int rc;
size_t size = sizeof (buffer);
if (pkcs8_key == NULL)
return NULL;
rc = gnutls_x509_privkey_init (&key);
if (rc)
return NULL;
data.size = strlen (pkcs8_key);
data.data = (void *) g_strdup (pkcs8_key);
rc = gnutls_x509_privkey_import_pkcs8 (key, &data, GNUTLS_X509_FMT_PEM,
passphrase ? passphrase : "", 0);
g_free (data.data);
if (rc)
{
gnutls_x509_privkey_deinit (key);
return NULL;
}
rc = gnutls_x509_privkey_export (key, GNUTLS_X509_FMT_PEM, buffer, &size);
gnutls_x509_privkey_deinit (key);
if (rc)
return NULL;
return g_strdup (buffer);
}
/**
* @brief Exports a base64 encoded public key from a private key and its
* passphrase.
*
* @param[in] private_key Private key to export.
* @param[in] passphrase Passphrase for the private key.
*
* @return Allocated base64 encoded public key if success, NULL otherwise.
*/
char *
gvm_ssh_public_from_private (const char *private_key, const char *passphrase)
{
ssh_key priv;
char *pub_key, *decrypted_priv, *pub_str = NULL;
const char *type;
int ret;
if (private_key == NULL)
return NULL;
decrypted_priv = gvm_ssh_pkcs8_decrypt (private_key, passphrase);
ret = ssh_pki_import_privkey_base64 (decrypted_priv ? decrypted_priv
: private_key,
passphrase, NULL, NULL, &priv);
g_free (decrypted_priv);
if (ret)
return NULL;
ret = ssh_pki_export_pubkey_base64 (priv, &pub_key);
type = ssh_key_type_to_char (ssh_key_type (priv));
#if LIBSSH_VERSION_INT >= SSH_VERSION_INT(0, 6, 4)
if (!strcmp (type, "ssh-ecdsa"))
type = ssh_pki_key_ecdsa_name (priv);
#endif
ssh_key_free (priv);
if (ret)
return NULL;
pub_str = g_strdup_printf ("%s %s", type, pub_key);
g_free (pub_key);
return pub_str;
}
/**
* @brief Gets information from a SSH private key.
*
* @param[in] private_key Private key to get info from.
* @param[in] passphrase Passphrase for the private key.
* @param[out] type Static string describing the type of the key.
* @param[out] sha256_hash The SHA-256 hash of the key.
*
* @return 0 on success, -1 on error.
*/
int
gvm_ssh_private_key_info (const char *private_key, const char *passphrase,
const char **type, char **sha256_hash)
{
ssh_key priv;
char *decrypted_priv;
int ret;
if (type)
*type = NULL;
if (sha256_hash)
*sha256_hash = NULL;
if (private_key == NULL)
return -1;
decrypted_priv = gvm_ssh_pkcs8_decrypt (private_key, passphrase);
ret = ssh_pki_import_privkey_base64 (decrypted_priv ? decrypted_priv
: private_key,
passphrase, NULL, NULL, &priv);
free (decrypted_priv);
if (ret)
return -1;
if (type)
{
*type = ssh_key_type_to_char (ssh_key_type (priv));
}
if (sha256_hash)
{
unsigned char *hash = NULL;
size_t hash_size = 0;
ret = ssh_get_publickey_hash (priv, SSH_PUBLICKEY_HASH_SHA256, &hash,
&hash_size);
if (ret == 0)
{
gchar *hex = g_malloc0 (hash_size * 2 + 1);
for (unsigned int i = 0; i < hash_size; i++)
{
g_snprintf (hex + i * 2, 3, "%02x", hash[i]);
}
ssh_clean_pubkey_hash (&hash);
*sha256_hash = hex;
}
}
ssh_key_free (priv);
if (ret)
return -1;
return 0;
}
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