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weechat/src/plugins/irc/irc-sasl.c
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/*
* irc-sasl.c - SASL authentication with IRC server
*
* Copyright (C) 2003-2017 Sébastien Helleu <flashcode@flashtux.org>
*
* This file is part of WeeChat, the extensible chat client.
*
* WeeChat is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* WeeChat 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with WeeChat. If not, see <http://www.gnu.org/licenses/>.
*/
#include <limits.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <arpa/inet.h>
#include <gcrypt.h>
#ifdef HAVE_GNUTLS
#include <gnutls/gnutls.h>
#if LIBGNUTLS_VERSION_NUMBER >= 0x020a01 /* 2.10.1 */
#include <gnutls/abstract.h>
#endif /* LIBGNUTLS_VERSION_NUMBER >= 0x020a01 */
#endif /* HAVE_GNUTLS */
#include "../weechat-plugin.h"
#include "irc.h"
#include "irc-sasl.h"
#include "irc-server.h"
/*
* these names are sent to the IRC server (as upper case), so they must be
* valid values for the AUTHENTICATE command (example: "AUTHENTICATE PLAIN")
*/
char *irc_sasl_mechanism_string[IRC_NUM_SASL_MECHANISMS] =
{ "plain", "ecdsa-nist256p-challenge", "external", "dh-blowfish", "dh-aes" };
/*
* Builds answer for SASL authentication, using mechanism "PLAIN".
*
* Note: result must be freed after use.
*/
char *
irc_sasl_mechanism_plain (const char *sasl_username, const char *sasl_password)
{
char *string, *answer_base64;
int length_username, length;
answer_base64 = NULL;
length_username = strlen (sasl_username);
length = ((length_username + 1) * 2) + strlen (sasl_password) + 1;
string = malloc (length);
if (string)
{
snprintf (string, length, "%s|%s|%s",
sasl_username, sasl_username, sasl_password);
string[length_username] = '\0';
string[(length_username * 2) + 1] = '\0';
answer_base64 = malloc (length * 4);
if (answer_base64)
weechat_string_encode_base64 (string, length - 1, answer_base64);
free (string);
}
return answer_base64;
}
/*
* Returns the content of file with SASL key.
*
* Note: result must be freed after use.
*/
char *
irc_sasl_get_key_content (struct t_irc_server *server, const char *sasl_key)
{
const char *weechat_dir;
char *key_path1, *key_path2, *content;
if (!sasl_key)
return NULL;
content = NULL;
weechat_dir = weechat_info_get ("weechat_dir", "");
key_path1 = weechat_string_replace (sasl_key, "%h", weechat_dir);
key_path2 = (key_path1) ?
weechat_string_expand_home (key_path1) : NULL;
if (key_path2)
content = weechat_file_get_content (key_path2);
if (!content)
{
weechat_printf (
server->buffer,
_("%s%s: unable to read private key in file \"%s\""),
weechat_prefix ("error"),
IRC_PLUGIN_NAME,
(key_path2) ? key_path2 : ((key_path1) ? key_path1 : sasl_key));
}
if (key_path1)
free (key_path1);
if (key_path2)
free (key_path2);
return content;
}
/*
* Builds answer for SASL authentication, using mechanism
* "ECDSA-NIST256P-CHALLENGE".
*
* Note: result must be freed after use.
*/
char *
irc_sasl_mechanism_ecdsa_nist256p_challenge (struct t_irc_server *server,
const char *data_base64,
const char *sasl_username,
const char *sasl_key)
{
#if defined(HAVE_GNUTLS) && (LIBGNUTLS_VERSION_NUMBER >= 0x030015) /* 3.0.21 */
char *data, *string, *answer_base64;
int length_data, length_username, length, ret;
char *str_privkey;
gnutls_x509_privkey_t x509_privkey;
gnutls_privkey_t privkey;
gnutls_datum_t filedatum, decoded_data, signature;
#if LIBGNUTLS_VERSION_NUMBER >= 0x030300 /* 3.3.0 */
gnutls_ecc_curve_t curve;
gnutls_datum_t x, y, k;
char *pubkey, *pubkey_base64;
#endif /* LIBGNUTLS_VERSION_NUMBER >= 0x030300 */
answer_base64 = NULL;
string = NULL;
length = 0;
if (strcmp (data_base64, "+") == 0)
{
/* send "username" + '\0' + "username" */
answer_base64 = NULL;
length_username = strlen (sasl_username);
length = length_username + 1 + length_username;
string = malloc (length + 1);
if (string)
{
snprintf (string, length + 1, "%s|%s", sasl_username, sasl_username);
string[length_username] = '\0';
}
}
else
{
/* sign the challenge with the private key and return the result */
/* decode the challenge */
data = malloc (strlen (data_base64) + 1);
if (!data)
return NULL;
length_data = weechat_string_decode_base64 (data_base64, data);
/* read file with private key */
str_privkey = irc_sasl_get_key_content (server, sasl_key);
if (!str_privkey)
{
free (data);
return NULL;
}
/* import key */
gnutls_x509_privkey_init (&x509_privkey);
gnutls_privkey_init (&privkey);
filedatum.data = (unsigned char *)str_privkey;
filedatum.size = strlen (str_privkey);
ret = gnutls_x509_privkey_import (x509_privkey, &filedatum,
GNUTLS_X509_FMT_PEM);
free (str_privkey);
if (ret != GNUTLS_E_SUCCESS)
{
weechat_printf (
server->buffer,
_("%sgnutls: invalid private key file: error %d %s"),
weechat_prefix ("error"),
ret,
gnutls_strerror (ret));
gnutls_x509_privkey_deinit (x509_privkey);
gnutls_privkey_deinit (privkey);
free (data);
return NULL;
}
#if LIBGNUTLS_VERSION_NUMBER >= 0x030300 /* 3.3.0 */
/* read raw values in key, to display public key */
ret = gnutls_x509_privkey_export_ecc_raw (x509_privkey,
&curve, &x, &y, &k);
if (ret == GNUTLS_E_SUCCESS)
{
pubkey = malloc (x.size + 1);
if (pubkey)
{
pubkey[0] = (y.data[y.size - 1] & 1) ? 0x03 : 0x02;
memcpy (pubkey + 1, x.data, x.size);
pubkey_base64 = malloc ((x.size + 1 + 1) * 4);
if (pubkey_base64)
{
weechat_string_encode_base64 (pubkey, x.size + 1,
pubkey_base64);
weechat_printf (
server->buffer,
_("%s%s: signing the challenge with ECC public key: "
"%s"),
weechat_prefix ("network"),
IRC_PLUGIN_NAME,
pubkey_base64);
free (pubkey_base64);
}
free (pubkey);
}
gnutls_free (x.data);
gnutls_free (y.data);
gnutls_free (k.data);
}
#endif /* LIBGNUTLS_VERSION_NUMBER >= 0x030300 */
/* import private key in an abstract key structure */
ret = gnutls_privkey_import_x509 (privkey, x509_privkey, 0); /* gnutls >= 2.11.0 */
if (ret != GNUTLS_E_SUCCESS)
{
weechat_printf (
server->buffer,
_("%sgnutls: unable to import the private key: error %d %s"),
weechat_prefix ("error"),
ret,
gnutls_strerror (ret));
gnutls_x509_privkey_deinit (x509_privkey);
gnutls_privkey_deinit (privkey);
free (data);
return NULL;
}
decoded_data.data = (unsigned char *)data;
decoded_data.size = length_data;
ret = gnutls_privkey_sign_hash (privkey, GNUTLS_DIG_SHA256, 0, /* gnutls >= 2.11.0 */
&decoded_data, &signature);
if (ret != GNUTLS_E_SUCCESS)
{
weechat_printf (
server->buffer,
_("%sgnutls: unable to sign the hashed data: error %d %s"),
weechat_prefix ("error"),
ret,
gnutls_strerror (ret));
gnutls_x509_privkey_deinit (x509_privkey);
gnutls_privkey_deinit (privkey);
free (data);
return NULL;
}
gnutls_x509_privkey_deinit (x509_privkey);
gnutls_privkey_deinit (privkey);
string = malloc (signature.size);
if (string)
memcpy (string, signature.data, signature.size);
length = signature.size;
gnutls_free (signature.data);
free (data);
}
if (string && (length > 0))
{
answer_base64 = malloc ((length + 1) * 4);
if (answer_base64)
weechat_string_encode_base64 (string, length, answer_base64);
free (string);
}
if (string)
free (string);
return answer_base64;
#else /* no gnutls or gnutls < 3.0.21 */
/* make C compiler happy */
(void) data_base64;
(void) sasl_username;
(void) sasl_key;
weechat_printf (server->buffer,
_("%sgnutls: version >= 3.0.21 is required for SASL "
"\"ecdsa-nist256p-challenge\""),
weechat_prefix ("error"));
return NULL;
#endif /* defined(HAVE_GNUTLS) && (LIBGNUTLS_VERSION_NUMBER >= 0x030015) */
}
/*
* Reads key sent by server (Diffie-Hellman key exchange).
*
* Returns:
* 1: OK
* 0: error
*/
int
irc_sasl_dh (const char *data_base64,
unsigned char **public_bin, unsigned char **secret_bin,
int *length_key)
{
char *data;
unsigned char *ptr_data;
int length_data, size, num_bits_prime_number, rc;
size_t num_written;
gcry_mpi_t data_prime_number, data_generator_number, data_server_pub_key;
gcry_mpi_t pub_key, priv_key, secret_mpi;
rc = 0;
data = NULL;
data_prime_number = NULL;
data_generator_number = NULL;
data_server_pub_key = NULL;
pub_key = NULL;
priv_key = NULL;
secret_mpi = NULL;
/* decode data */
data = malloc (strlen (data_base64) + 1);
if (!data)
goto dhend;
length_data = weechat_string_decode_base64 (data_base64, data);
ptr_data = (unsigned char *)data;
/* extract prime number */
size = ntohs ((((unsigned int)ptr_data[1]) << 8) | ptr_data[0]);
ptr_data += 2;
length_data -= 2;
if (size > length_data)
goto dhend;
data_prime_number = gcry_mpi_new (size * 8);
gcry_mpi_scan (&data_prime_number, GCRYMPI_FMT_USG, ptr_data, size, NULL);
num_bits_prime_number = gcry_mpi_get_nbits (data_prime_number);
if (num_bits_prime_number == 0 || INT_MAX - 7 < num_bits_prime_number)
goto dhend;
ptr_data += size;
length_data -= size;
/* extract generator number */
size = ntohs ((((unsigned int)ptr_data[1]) << 8) | ptr_data[0]);
ptr_data += 2;
length_data -= 2;
if (size > length_data)
goto dhend;
data_generator_number = gcry_mpi_new (size * 8);
gcry_mpi_scan (&data_generator_number, GCRYMPI_FMT_USG, ptr_data, size, NULL);
ptr_data += size;
length_data -= size;
/* extract server-generated public key */
size = ntohs ((((unsigned int)ptr_data[1]) << 8) | ptr_data[0]);
ptr_data += 2;
length_data -= 2;
if (size > length_data)
goto dhend;
data_server_pub_key = gcry_mpi_new (size * 8);
gcry_mpi_scan (&data_server_pub_key, GCRYMPI_FMT_USG, ptr_data, size, NULL);
/* generate keys */
pub_key = gcry_mpi_new (num_bits_prime_number);
priv_key = gcry_mpi_new (num_bits_prime_number);
gcry_mpi_randomize (priv_key, num_bits_prime_number, GCRY_STRONG_RANDOM);
/* pub_key = (g ^ priv_key) % p */
gcry_mpi_powm (pub_key, data_generator_number, priv_key, data_prime_number);
/* compute secret_bin */
*length_key = (num_bits_prime_number + 7) / 8;
*secret_bin = malloc (*length_key);
secret_mpi = gcry_mpi_new (num_bits_prime_number);
/* secret_mpi = (y ^ priv_key) % p */
gcry_mpi_powm (secret_mpi, data_server_pub_key, priv_key, data_prime_number);
gcry_mpi_print (GCRYMPI_FMT_USG, *secret_bin, *length_key,
&num_written, secret_mpi);
/* create public_bin */
*public_bin = malloc (*length_key);
gcry_mpi_print (GCRYMPI_FMT_USG, *public_bin, *length_key,
&num_written, pub_key);
rc = 1;
dhend:
if (data)
free (data);
if (data_prime_number)
gcry_mpi_release (data_prime_number);
if (data_generator_number)
gcry_mpi_release (data_generator_number);
if (data_server_pub_key)
gcry_mpi_release (data_server_pub_key);
if (pub_key)
gcry_mpi_release (pub_key);
if (priv_key)
gcry_mpi_release (priv_key);
if (secret_mpi)
gcry_mpi_release (secret_mpi);
return rc;
}
/*
* Builds answer for SASL authentication, using mechanism "DH-BLOWFISH".
*
* Argument data_base64 is a concatenation of 3 strings, each string is composed
* of 2 bytes (length of string), followed by content of string:
* 1. a prime number
* 2. a generator number
* 3. server-generated public key
*
* Note: result must be freed after use.
*/
char *
irc_sasl_mechanism_dh_blowfish (const char *data_base64,
const char *sasl_username,
const char *sasl_password)
{
char *answer, *ptr_answer, *answer_base64;
unsigned char *password_clear, *password_crypted;
int length_key, length_username, length_password, length_answer;
unsigned char *public_bin, *secret_bin;
gcry_cipher_hd_t gcrypt_handle;
password_clear = NULL;
password_crypted = NULL;
answer = NULL;
answer_base64 = NULL;
secret_bin = NULL;
public_bin = NULL;
if (!irc_sasl_dh (data_base64, &public_bin, &secret_bin, &length_key))
goto bfend;
/* create password buffers (clear and crypted) */
length_password = strlen (sasl_password) +
((8 - (strlen (sasl_password) % 8)) % 8);
password_clear = malloc (length_password);
password_crypted = malloc (length_password);
memset (password_clear, 0, length_password);
memset (password_crypted, 0, length_password);
memcpy (password_clear, sasl_password, strlen (sasl_password));
/* crypt password using blowfish */
if (gcry_cipher_open (&gcrypt_handle, GCRY_CIPHER_BLOWFISH,
GCRY_CIPHER_MODE_ECB, 0) != 0)
goto bfend;
if (gcry_cipher_setkey (gcrypt_handle, secret_bin, length_key) != 0)
goto bfend;
if (gcry_cipher_encrypt (gcrypt_handle,
password_crypted, length_password,
password_clear, length_password) != 0)
goto bfend;
gcry_cipher_close (gcrypt_handle);
/*
* build answer for server, it is concatenation of:
* 1. key length (2 bytes)
* 2. public key ('length_key' bytes)
* 3. sasl_username ('length_username'+1 bytes)
* 4. encrypted password ('length_password' bytes)
*/
length_username = strlen (sasl_username) + 1;
length_answer = 2 + length_key + length_username + length_password;
answer = malloc (length_answer);
ptr_answer = answer;
*((unsigned int *)ptr_answer) = htons(length_key);
ptr_answer += 2;
memcpy (ptr_answer, public_bin, length_key);
ptr_answer += length_key;
memcpy (ptr_answer, sasl_username, length_username);
ptr_answer += length_username;
memcpy (ptr_answer, password_crypted, length_password);
/* encode answer to base64 */
answer_base64 = malloc ((length_answer + 1) * 4);
if (answer_base64)
weechat_string_encode_base64 (answer, length_answer, answer_base64);
bfend:
if (secret_bin)
free (secret_bin);
if (public_bin)
free (public_bin);
if (password_clear)
free (password_clear);
if (password_crypted)
free (password_crypted);
if (answer)
free (answer);
return answer_base64;
}
/*
* Builds answer for SASL authentication, using mechanism "DH-AES".
*
* Argument data_base64 is a concatenation of 3 strings, each string is composed
* of 2 bytes (length of string), followed by content of string:
* 1. a prime number
* 2. a generator number
* 3. server-generated public key
*
* Note: result must be freed after use.
*/
char *
irc_sasl_mechanism_dh_aes (const char *data_base64,
const char *sasl_username,
const char *sasl_password)
{
char *answer, *ptr_answer, *answer_base64;
unsigned char *ptr_userpass, *userpass_clear, *userpass_crypted;
int length_key, length_answer;
int length_username, length_password, length_userpass;
unsigned char *public_bin, *secret_bin;
char iv[16];
int cipher_algo;
gcry_cipher_hd_t gcrypt_handle;
userpass_clear = NULL;
userpass_crypted = NULL;
answer = NULL;
answer_base64 = NULL;
secret_bin = NULL;
public_bin = NULL;
if (irc_sasl_dh(data_base64, &public_bin, &secret_bin, &length_key) == 0)
goto aesend;
/* Select cipher algorithm: key length * 8 = cipher bit size */
switch (length_key)
{
case 32:
cipher_algo = GCRY_CIPHER_AES256;
break;
case 24:
cipher_algo = GCRY_CIPHER_AES192;
break;
case 16:
cipher_algo = GCRY_CIPHER_AES128;
break;
default:
/* Invalid bit length */
goto aesend;
}
/* Generate the IV */
gcry_randomize (iv, sizeof (iv), GCRY_STRONG_RANDOM);
/* create user/pass buffers (clear and crypted) */
length_username = strlen (sasl_username) + 1;
length_password = strlen (sasl_password) + 1;
length_userpass = length_username + length_password +
((16 - ((length_username + length_password) % 16)) % 16);
ptr_userpass = userpass_clear = malloc (length_userpass);
userpass_crypted = malloc (length_userpass);
memset (userpass_clear, 0, length_password);
memset (userpass_crypted, 0, length_password);
memcpy (ptr_userpass, sasl_username, length_username);
ptr_userpass += length_username;
memcpy (ptr_userpass, sasl_password, length_password);
/* crypt password using AES in CBC mode */
if (gcry_cipher_open (&gcrypt_handle, cipher_algo,
GCRY_CIPHER_MODE_CBC, 0) != 0)
goto aesend;
if (gcry_cipher_setkey (gcrypt_handle, secret_bin, length_key) != 0)
goto aesend;
if (gcry_cipher_setiv (gcrypt_handle, iv, sizeof(iv)) != 0)
goto aesend;
if (gcry_cipher_encrypt (gcrypt_handle,
userpass_crypted, length_userpass,
userpass_clear, length_userpass) != 0)
goto aesend;
gcry_cipher_close (gcrypt_handle);
/*
* build answer for server, it is concatenation of:
* 1. key length (2 bytes)
* 2. public key ('length_key' bytes)
* 3. IV (sizeof (iv) bytes)
* 4. encrypted password ('length_userpass' bytes)
*/
length_answer = 2 + length_key + sizeof (iv) + length_userpass;
answer = malloc (length_answer);
ptr_answer = answer;
*((unsigned int *)ptr_answer) = htons(length_key);
ptr_answer += 2;
memcpy (ptr_answer, public_bin, length_key);
ptr_answer += length_key;
memcpy (ptr_answer, iv, sizeof (iv));
ptr_answer += sizeof (iv);
memcpy (ptr_answer, userpass_crypted, length_userpass);
/* encode answer to base64 */
answer_base64 = malloc ((length_answer + 1) * 4);
if (answer_base64)
weechat_string_encode_base64 (answer, length_answer, answer_base64);
aesend:
if (secret_bin)
free (secret_bin);
if (public_bin)
free (public_bin);
if (userpass_clear)
free (userpass_clear);
if (userpass_crypted)
free (userpass_crypted);
if (answer)
free (answer);
return answer_base64;
}
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