/*
* pki_container_openssh.c
* This file is part of the SSH Library
*
* Copyright (c) 2013,2014 Aris Adamantiadis <aris@badcode.be>
*
* 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.
*/
/**
* @ingroup libssh_pki
* *
* @{
*/
#include "config.h"
#include <ctype.h>
#include <string.h>
#include <stdbool.h>
#include "libssh/libssh.h"
#include "libssh/priv.h"
#include "libssh/pki.h"
#include "libssh/pki_priv.h"
#include "libssh/buffer.h"
/**
* @internal
*
* @brief Import a private key from a ssh buffer.
*
* @param[in] key_blob_buffer The key blob to import as specified in
* key.c:key_private_serialize in OpenSSH source
* code.
*
* @param[out] pkey A pointer where the allocated key can be stored. You
* need to free the memory.
*
* @return SSH_OK on success, SSH_ERROR on error.
*
* @see ssh_key_free()
*/
static int pki_openssh_import_privkey_blob(ssh_buffer key_blob_buffer,
ssh_key *pkey)
{
enum ssh_keytypes_e type;
char *type_s = NULL;
ssh_key key = NULL;
int rc;
if (pkey == NULL) {
return SSH_ERROR;
}
rc = ssh_buffer_unpack(key_blob_buffer, "s", &type_s);
if (rc == SSH_ERROR){
SSH_LOG(SSH_LOG_WARN, "Unpack error");
return SSH_ERROR;
}
type = ssh_key_type_from_name(type_s);
if (type == SSH_KEYTYPE_UNKNOWN) {
SSH_LOG(SSH_LOG_WARN, "Unknown key type '%s' found!", type_s);
return SSH_ERROR;
}
SAFE_FREE(type_s);
rc = pki_import_privkey_buffer(type, key_blob_buffer, &key);
if (rc != SSH_OK) {
SSH_LOG(SSH_LOG_WARN, "Failed to read key in OpenSSH format");
goto fail;
}
*pkey = key;
return SSH_OK;
fail:
ssh_key_free(key);
return SSH_ERROR;
}
/**
* @brief decrypts an encrypted private key blob in OpenSSH format.
*
*/
static int pki_private_key_decrypt(ssh_string blob,
const char* passphrase,
const char *ciphername,
const char *kdfname,
ssh_string kdfoptions,
ssh_auth_callback auth_fn,
void *auth_data)
{
struct ssh_cipher_struct *ciphers = ssh_get_ciphertab();
struct ssh_cipher_struct cipher;
uint8_t key_material[128] = {0};
char passphrase_buffer[128] = {0};
size_t key_material_len;
ssh_buffer buffer = NULL;
ssh_string salt = NULL;
uint32_t rounds;
int cmp;
int rc;
int i;
cmp = strcmp(ciphername, "none");
if (cmp == 0){
/* no decryption required */
return SSH_OK;
}
for (i = 0; ciphers[i].name != NULL; i++) {
cmp = strcmp(ciphername, ciphers[i].name);
if (cmp == 0){
memcpy(&cipher, &ciphers[i], sizeof(cipher));
break;
}
}
if (ciphers[i].name == NULL){
SSH_LOG(SSH_LOG_WARN, "Unsupported cipher %s", ciphername);
return SSH_ERROR;
}
cmp = strcmp(kdfname, "bcrypt");
if (cmp != 0) {
SSH_LOG(SSH_LOG_WARN, "Unsupported KDF %s", kdfname);
return SSH_ERROR;
}
if (ssh_string_len(blob) % cipher.blocksize != 0) {
SSH_LOG(SSH_LOG_WARN,
"Encrypted string not multiple of blocksize: %zu",
ssh_string_len(blob));
return SSH_ERROR;
}
buffer = ssh_buffer_new();
if (buffer == NULL){
return SSH_ERROR;
}
rc = ssh_buffer_add_data(buffer,
ssh_string_data(kdfoptions),
ssh_string_len(kdfoptions));
if (rc != SSH_ERROR){
rc = ssh_buffer_unpack(buffer, "Sd", &salt, &rounds);
}
SSH_BUFFER_FREE(buffer);
if (rc == SSH_ERROR){
return SSH_ERROR;
}
/* We need material for key (keysize bits / 8) and IV (blocksize) */
key_material_len = cipher.keysize/8 + cipher.blocksize;
if (key_material_len > sizeof(key_material)) {
SSH_LOG(SSH_LOG_WARN, "Key material too big");
return SSH_ERROR;
}
SSH_LOG(SSH_LOG_DEBUG,
"Decryption: %d key, %d IV, %d rounds, %zu bytes salt",
cipher.keysize/8,
cipher.blocksize,
rounds,
ssh_string_len(salt));
if (passphrase == NULL) {
if (auth_fn == NULL) {
SAFE_FREE(salt);
SSH_LOG(SSH_LOG_WARN, "No passphrase provided");
return SSH_ERROR;
}
rc = auth_fn("Passphrase",
passphrase_buffer,
sizeof(passphrase_buffer),
0,
0,
auth_data);
if (rc != SSH_OK) {
SAFE_FREE(salt);
return SSH_ERROR;
}
passphrase = passphrase_buffer;
}
rc = bcrypt_pbkdf(passphrase,
strlen(passphrase),
ssh_string_data(salt),
ssh_string_len(salt),
key_material,
key_material_len,
rounds);
SAFE_FREE(salt);
if (rc < 0){
return SSH_ERROR;
}
explicit_bzero(passphrase_buffer, sizeof(passphrase_buffer));
cipher.set_decrypt_key(&cipher,
key_material,
key_material + cipher.keysize/8);
cipher.decrypt(&cipher,
ssh_string_data(blob),
ssh_string_data(blob),
ssh_string_len(blob));
ssh_cipher_clear(&cipher);
return SSH_OK;
}
/** @internal
* @brief Import a private key in OpenSSH (new) format. This format is
* typically used with ed25519 keys but can be used for others.
*/
static ssh_key
ssh_pki_openssh_import(const char *text_key,
const char *passphrase,
ssh_auth_callback auth_fn,
void *auth_data,
bool private)
{
const char *ptr = text_key;
const char *end;
char *base64;
int cmp;
int rc;
int i;
ssh_buffer buffer = NULL, privkey_buffer=NULL;
char *magic = NULL, *ciphername = NULL, *kdfname = NULL;
uint32_t nkeys = 0, checkint1 = 0, checkint2 = 0xFFFF;
ssh_string kdfoptions = NULL;
ssh_string pubkey0 = NULL;
ssh_string privkeys = NULL;
ssh_string comment = NULL;
ssh_key key = NULL;
uint8_t padding;
cmp = strncmp(ptr, OPENSSH_HEADER_BEGIN, strlen(OPENSSH_HEADER_BEGIN));
if (cmp != 0) {
SSH_LOG(SSH_LOG_WARN, "Not an OpenSSH private key (no header)");
goto out;
}
ptr += strlen(OPENSSH_HEADER_BEGIN);
while(ptr[0] != '\0' && !isspace((int)ptr[0])) {
ptr++;
}
end = strstr(ptr, OPENSSH_HEADER_END);
if (end == NULL) {
SSH_LOG(SSH_LOG_WARN, "Not an OpenSSH private key (no footer)");
goto out;
}
base64 = malloc(end - ptr + 1);
if (base64 == NULL) {
goto out;
}
for (i = 0; ptr < end; ptr++) {
if (!isspace((int)ptr[0])) {
base64[i] = ptr[0];
i++;
}
}
base64[i] = '\0';
buffer = base64_to_bin(base64);
SAFE_FREE(base64);
if (buffer == NULL) {
SSH_LOG(SSH_LOG_WARN, "Not an OpenSSH private key (base64 error)");
goto out;
}
rc = ssh_buffer_unpack(buffer, "PssSdSS",
strlen(OPENSSH_AUTH_MAGIC) + 1,
&magic,
&ciphername,
&kdfname,
&kdfoptions,
&nkeys,
&pubkey0,
&privkeys);
if (rc == SSH_ERROR) {
SSH_LOG(SSH_LOG_WARN, "Not an OpenSSH private key (unpack error)");
goto out;
}
cmp = strncmp(magic, OPENSSH_AUTH_MAGIC, strlen(OPENSSH_AUTH_MAGIC));
if (cmp != 0) {
SSH_LOG(SSH_LOG_WARN, "Not an OpenSSH private key (bad magic)");
goto out;
}
SSH_LOG(SSH_LOG_INFO,
"Opening OpenSSH private key: ciphername: %s, kdf: %s, nkeys: %d",
ciphername,
kdfname,
nkeys);
if (nkeys != 1) {
SSH_LOG(SSH_LOG_WARN, "Opening OpenSSH private key: only 1 key supported (%d available)", nkeys);
goto out;
}
/* If we are interested only in public key do not progress
* to the key decryption later
*/
if (!private) {
rc = ssh_pki_import_pubkey_blob(pubkey0, &key);
if (rc != SSH_OK) {
SSH_LOG(SSH_LOG_WARN, "Failed to import public key blob");
}
/* in either case we clean up here */
goto out;
}
rc = pki_private_key_decrypt(privkeys,
passphrase,
ciphername,
kdfname,
kdfoptions,
auth_fn,
auth_data);
if (rc == SSH_ERROR) {
goto out;
}
privkey_buffer = ssh_buffer_new();
if (privkey_buffer == NULL) {
goto out;
}
ssh_buffer_set_secure(privkey_buffer);
ssh_buffer_add_data(privkey_buffer,
ssh_string_data(privkeys),
ssh_string_len(privkeys));
rc = ssh_buffer_unpack(privkey_buffer, "dd", &checkint1, &checkint2);
if (rc == SSH_ERROR || checkint1 != checkint2) {
SSH_LOG(SSH_LOG_WARN, "OpenSSH private key unpack error (correct password?)");
goto out;
}
rc = pki_openssh_import_privkey_blob(privkey_buffer, &key);
if (rc == SSH_ERROR) {
goto out;
}
comment = ssh_buffer_get_ssh_string(privkey_buffer);
SAFE_FREE(comment);
/* verify that the remaining data is correct padding */
for (i = 1; ssh_buffer_get_len(privkey_buffer) > 0; ++i) {
ssh_buffer_get_u8(privkey_buffer, &padding);
if (padding != i) {
ssh_key_free(key);
key = NULL;
SSH_LOG(SSH_LOG_WARN, "Invalid padding");
goto out;
}
}
out:
if (buffer != NULL) {
SSH_BUFFER_FREE(buffer);
buffer = NULL;
}
if (privkey_buffer != NULL) {
SSH_BUFFER_FREE(privkey_buffer);
privkey_buffer = NULL;
}
SAFE_FREE(magic);
SAFE_FREE(ciphername);
SAFE_FREE(kdfname);
SAFE_FREE(kdfoptions);
SAFE_FREE(pubkey0);
SAFE_FREE(privkeys);
return key;
}
ssh_key ssh_pki_openssh_privkey_import(const char *text_key,
const char *passphrase,
ssh_auth_callback auth_fn,
void *auth_data)
{
return ssh_pki_openssh_import(text_key, passphrase, auth_fn, auth_data, true);
}
ssh_key ssh_pki_openssh_pubkey_import(const char *text_key)
{
return ssh_pki_openssh_import(text_key, NULL, NULL, NULL, false);
}
/** @internal
* @brief exports a private key to a string blob.
* @param[in] privkey private key to convert
* @param[out] buffer buffer to write the blob in.
* @returns SSH_OK on success
* @warning only supports ed25519 key type at the moment.
*/
static int pki_openssh_export_privkey_blob(const ssh_key privkey,
ssh_buffer buffer)
{
int rc;
if (privkey->type != SSH_KEYTYPE_ED25519) {
SSH_LOG(SSH_LOG_WARN, "Type %s not supported", privkey->type_c);
return SSH_ERROR;
}
if (privkey->ed25519_privkey == NULL ||
privkey->ed25519_pubkey == NULL) {
return SSH_ERROR;
}
rc = ssh_buffer_pack(buffer,
"sdPdPP",
privkey->type_c,
(uint32_t)ED25519_KEY_LEN,
(size_t)ED25519_KEY_LEN, privkey->ed25519_pubkey,
(uint32_t)(2 * ED25519_KEY_LEN),
(size_t)ED25519_KEY_LEN, privkey->ed25519_privkey,
(size_t)ED25519_KEY_LEN, privkey->ed25519_pubkey);
return rc;
}
/** @internal
* @brief encrypts an ed25519 private key blob
*
*/
static int pki_private_key_encrypt(ssh_buffer privkey_buffer,
const char* passphrase,
const char *ciphername,
const char *kdfname,
ssh_auth_callback auth_fn,
void *auth_data,
uint32_t rounds,
ssh_string salt)
{
struct ssh_cipher_struct *ciphers = ssh_get_ciphertab();
struct ssh_cipher_struct cipher;
uint8_t key_material[128] = {0};
size_t key_material_len;
char passphrase_buffer[128] = {0};
int rc;
int i;
int cmp;
cmp = strcmp(ciphername, "none");
if (cmp == 0){
/* no encryption required */
return SSH_OK;
}
for (i = 0; ciphers[i].name != NULL; i++) {
cmp = strcmp(ciphername, ciphers[i].name);
if (cmp == 0){
memcpy(&cipher, &ciphers[i], sizeof(cipher));
break;
}
}
if (ciphers[i].name == NULL){
SSH_LOG(SSH_LOG_WARN, "Unsupported cipher %s", ciphername);
return SSH_ERROR;
}
cmp = strcmp(kdfname, "bcrypt");
if (cmp != 0){
SSH_LOG(SSH_LOG_WARN, "Unsupported KDF %s", kdfname);
return SSH_ERROR;
}
/* We need material for key (keysize bits / 8) and IV (blocksize) */
key_material_len = cipher.keysize/8 + cipher.blocksize;
if (key_material_len > sizeof(key_material)){
SSH_LOG(SSH_LOG_WARN, "Key material too big");
return SSH_ERROR;
}
SSH_LOG(SSH_LOG_WARN, "Encryption: %d key, %d IV, %d rounds, %zu bytes salt",
cipher.keysize/8,
cipher.blocksize, rounds, ssh_string_len(salt));
if (passphrase == NULL){
if (auth_fn == NULL){
SSH_LOG(SSH_LOG_WARN, "No passphrase provided");
return SSH_ERROR;
}
rc = auth_fn("Passphrase",
passphrase_buffer,
sizeof(passphrase_buffer),
0,
0,
auth_data);
if (rc != SSH_OK){
return SSH_ERROR;
}
passphrase = passphrase_buffer;
}
rc = bcrypt_pbkdf(passphrase,
strlen(passphrase),
ssh_string_data(salt),
ssh_string_len(salt),
key_material,
key_material_len,
rounds);
if (rc < 0){
return SSH_ERROR;
}
cipher.set_encrypt_key(&cipher,
key_material,
key_material + cipher.keysize/8);
cipher.encrypt(&cipher,
ssh_buffer_get(privkey_buffer),
ssh_buffer_get(privkey_buffer),
ssh_buffer_get_len(privkey_buffer));
ssh_cipher_clear(&cipher);
explicit_bzero(passphrase_buffer, sizeof(passphrase_buffer));
return SSH_OK;
}
/** @internal
* generate an OpenSSH private key (defined in PROTOCOL.key) and output it in text format.
* @param privkey[in] private key to export
* @returns an SSH string containing the text representation of the exported key.
* @warning currently only supports ED25519 key types.
*/
ssh_string ssh_pki_openssh_privkey_export(const ssh_key privkey,
const char *passphrase,
ssh_auth_callback auth_fn,
void *auth_data)
{
ssh_buffer buffer;
ssh_string str = NULL;
ssh_string pubkey_s=NULL;
ssh_buffer privkey_buffer = NULL;
uint32_t rnd;
uint32_t rounds = 16;
ssh_string salt=NULL;
ssh_string kdf_options=NULL;
int to_encrypt=0;
unsigned char *b64;
uint32_t str_len, len;
uint8_t padding = 1;
int ok;
int rc;
if (privkey == NULL) {
return NULL;
}
if (privkey->type != SSH_KEYTYPE_ED25519){
SSH_LOG(SSH_LOG_WARN, "Unsupported key type %s", privkey->type_c);
return NULL;
}
if (passphrase != NULL || auth_fn != NULL){
SSH_LOG(SSH_LOG_INFO, "Enabling encryption for private key export");
to_encrypt = 1;
}
buffer = ssh_buffer_new();
pubkey_s = pki_publickey_to_blob(privkey);
if(buffer == NULL || pubkey_s == NULL){
goto error;
}
ok = ssh_get_random(&rnd, sizeof(rnd), 0);
if (!ok) {
goto error;
}
privkey_buffer = ssh_buffer_new();
if (privkey_buffer == NULL) {
goto error;
}
/* checkint1 & 2 */
rc = ssh_buffer_pack(privkey_buffer,
"dd",
rnd,
rnd);
if (rc == SSH_ERROR){
goto error;
}
rc = pki_openssh_export_privkey_blob(privkey, privkey_buffer);
if (rc == SSH_ERROR){
goto error;
}
/* comment */
rc = ssh_buffer_pack(privkey_buffer, "s", "" /* comment */);
if (rc == SSH_ERROR){
goto error;
}
/* Add padding regardless encryption because it is expected
* by OpenSSH tools.
* XXX Using 16 B as we use only AES cipher below anyway.
*/
while (ssh_buffer_get_len(privkey_buffer) % 16 != 0) {
rc = ssh_buffer_add_u8(privkey_buffer, padding);
if (rc < 0) {
goto error;
}
padding++;
}
if (to_encrypt){
ssh_buffer kdf_buf;
kdf_buf = ssh_buffer_new();
if (kdf_buf == NULL) {
goto error;
}
salt = ssh_string_new(16);
if (salt == NULL){
SSH_BUFFER_FREE(kdf_buf);
goto error;
}
ok = ssh_get_random(ssh_string_data(salt), 16, 0);
if (!ok) {
SSH_BUFFER_FREE(kdf_buf);
goto error;
}
ssh_buffer_pack(kdf_buf, "Sd", salt, rounds);
kdf_options = ssh_string_new(ssh_buffer_get_len(kdf_buf));
if (kdf_options == NULL){
SSH_BUFFER_FREE(kdf_buf);
goto error;
}
memcpy(ssh_string_data(kdf_options),
ssh_buffer_get(kdf_buf),
ssh_buffer_get_len(kdf_buf));
SSH_BUFFER_FREE(kdf_buf);
rc = pki_private_key_encrypt(privkey_buffer,
passphrase,
"aes128-cbc",
"bcrypt",
auth_fn,
auth_data,
rounds,
salt);
if (rc != SSH_OK){
goto error;
}
} else {
kdf_options = ssh_string_new(0);
}
rc = ssh_buffer_pack(buffer,
"PssSdSdP",
(size_t)strlen(OPENSSH_AUTH_MAGIC) + 1, OPENSSH_AUTH_MAGIC,
to_encrypt ? "aes128-cbc" : "none", /* ciphername */
to_encrypt ? "bcrypt" : "none", /* kdfname */
kdf_options, /* kdfoptions */
(uint32_t) 1, /* nkeys */
pubkey_s,
(uint32_t)ssh_buffer_get_len(privkey_buffer),
/* rest of buffer is a string */
(size_t)ssh_buffer_get_len(privkey_buffer), ssh_buffer_get(privkey_buffer));
if (rc != SSH_OK) {
goto error;
}
b64 = bin_to_base64(ssh_buffer_get(buffer),
ssh_buffer_get_len(buffer));
if (b64 == NULL){
goto error;
}
/* we can reuse the buffer */
ssh_buffer_reinit(buffer);
rc = ssh_buffer_pack(buffer,
"tttttt",
OPENSSH_HEADER_BEGIN,
"\n",
b64,
"\n",
OPENSSH_HEADER_END,
"\n");
explicit_bzero(b64, strlen((char *)b64));
SAFE_FREE(b64);
if (rc != SSH_OK){
goto error;
}
str = ssh_string_new(ssh_buffer_get_len(buffer));
if (str == NULL){
goto error;
}
str_len = ssh_buffer_get_len(buffer);
len = ssh_buffer_get_data(buffer, ssh_string_data(str), str_len);
if (str_len != len) {
SSH_STRING_FREE(str);
str = NULL;
}
error:
if (privkey_buffer != NULL) {
void *bufptr = ssh_buffer_get(privkey_buffer);
explicit_bzero(bufptr, ssh_buffer_get_len(privkey_buffer));
SSH_BUFFER_FREE(privkey_buffer);
}
SAFE_FREE(pubkey_s);
SAFE_FREE(kdf_options);
SAFE_FREE(salt);
if (buffer != NULL) {
SSH_BUFFER_FREE(buffer);
}
return str;
}
/**
* @}
*/