/*
* Copyright (c) 2008 The DragonFly Project. All rights reserved.
*
* This code is derived from software contributed to The DragonFly Project
* by Matthias Schmidt <matthias@dragonflybsd.org>, University of Marburg,
* Germany.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name of The DragonFly Project nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific, prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <openssl/x509.h>
#include <openssl/md5.h>
#include <openssl/ssl.h>
#include <openssl/err.h>
#include <openssl/pem.h>
#include <openssl/rand.h>
#include <string.h>
#include <syslog.h>
#include "dma.h"
static int
init_cert_file(SSL_CTX *ctx, const char *path)
{
int error;
/* Load certificate into ctx */
error = SSL_CTX_use_certificate_chain_file(ctx, path);
if (error < 1) {
syslog(LOG_ERR, "SSL: Cannot load certificate `%s': %s", path, ssl_errstr());
return (-1);
}
/* Add private key to ctx */
error = SSL_CTX_use_PrivateKey_file(ctx, path, SSL_FILETYPE_PEM);
if (error < 1) {
syslog(LOG_ERR, "SSL: Cannot load private key `%s': %s", path, ssl_errstr());
return (-1);
}
/*
* Check the consistency of a private key with the corresponding
* certificate
*/
error = SSL_CTX_check_private_key(ctx);
if (error < 1) {
syslog(LOG_ERR, "SSL: Cannot check private key: %s", ssl_errstr());
return (-1);
}
return (0);
}
int
smtp_init_crypto(int fd, int feature)
{
SSL_CTX *ctx = NULL;
#if (OPENSSL_VERSION_NUMBER >= 0x00909000L)
const SSL_METHOD *meth = NULL;
#else
SSL_METHOD *meth = NULL;
#endif
X509 *cert;
int error;
/* XXX clean up on error/close */
/* Init SSL library */
SSL_library_init();
SSL_load_error_strings();
// Allow any possible version
#if (OPENSSL_VERSION_NUMBER >= 0x10100000L)
meth = TLS_client_method();
#else
meth = SSLv23_client_method();
#endif
ctx = SSL_CTX_new(meth);
if (ctx == NULL) {
syslog(LOG_WARNING, "remote delivery deferred: SSL init failed: %s", ssl_errstr());
return (1);
}
/* User supplied a certificate */
if (config.certfile != NULL) {
error = init_cert_file(ctx, config.certfile);
if (error) {
syslog(LOG_WARNING, "remote delivery deferred");
return (1);
}
}
/*
* If the user wants STARTTLS, we have to send EHLO here
*/
if (((feature & SECURETRANS) != 0) &&
(feature & STARTTLS) != 0) {
/* TLS init phase, disable SSL_write */
config.features |= NOSSL;
send_remote_command(fd, "EHLO %s", hostname());
if (read_remote(fd, 0, NULL) == 2) {
send_remote_command(fd, "STARTTLS");
if (read_remote(fd, 0, NULL) != 2) {
if ((feature & TLS_OPP) == 0) {
syslog(LOG_ERR, "remote delivery deferred: STARTTLS not available: %s", neterr);
return (1);
} else {
syslog(LOG_INFO, "in opportunistic TLS mode, STARTTLS not available: %s", neterr);
return (0);
}
}
}
/* End of TLS init phase, enable SSL_write/read */
config.features &= ~NOSSL;
}
config.ssl = SSL_new(ctx);
if (config.ssl == NULL) {
syslog(LOG_NOTICE, "remote delivery deferred: SSL struct creation failed: %s",
ssl_errstr());
return (1);
}
/* Set ssl to work in client mode */
SSL_set_connect_state(config.ssl);
/* Set fd for SSL in/output */
error = SSL_set_fd(config.ssl, fd);
if (error == 0) {
syslog(LOG_NOTICE, "remote delivery deferred: SSL set fd failed: %s",
ssl_errstr());
return (1);
}
/* Open SSL connection */
error = SSL_connect(config.ssl);
if (error < 0) {
syslog(LOG_ERR, "remote delivery deferred: SSL handshake failed fatally: %s",
ssl_errstr());
return (1);
}
/* Get peer certificate */
cert = SSL_get_peer_certificate(config.ssl);
if (cert == NULL) {
syslog(LOG_WARNING, "remote delivery deferred: Peer did not provide certificate: %s",
ssl_errstr());
}
X509_free(cert);
return (0);
}
/*
* hmac_md5() taken out of RFC 2104. This RFC was written by H. Krawczyk,
* M. Bellare and R. Canetti.
*
* text pointer to data stream
* text_len length of data stream
* key pointer to authentication key
* key_len length of authentication key
* digest caller digest to be filled int
*/
void
hmac_md5(unsigned char *text, int text_len, unsigned char *key, int key_len,
unsigned char* digest)
{
MD5_CTX context;
unsigned char k_ipad[65]; /* inner padding -
* key XORd with ipad
*/
unsigned char k_opad[65]; /* outer padding -
* key XORd with opad
*/
unsigned char tk[16];
int i;
/* if key is longer than 64 bytes reset it to key=MD5(key) */
if (key_len > 64) {
MD5_CTX tctx;
MD5_Init(&tctx);
MD5_Update(&tctx, key, key_len);
MD5_Final(tk, &tctx);
key = tk;
key_len = 16;
}
/*
* the HMAC_MD5 transform looks like:
*
* MD5(K XOR opad, MD5(K XOR ipad, text))
*
* where K is an n byte key
* ipad is the byte 0x36 repeated 64 times
*
* opad is the byte 0x5c repeated 64 times
* and text is the data being protected
*/
/* start out by storing key in pads */
bzero( k_ipad, sizeof k_ipad);
bzero( k_opad, sizeof k_opad);
bcopy( key, k_ipad, key_len);
bcopy( key, k_opad, key_len);
/* XOR key with ipad and opad values */
for (i=0; i<64; i++) {
k_ipad[i] ^= 0x36;
k_opad[i] ^= 0x5c;
}
/*
* perform inner MD5
*/
MD5_Init(&context); /* init context for 1st
* pass */
MD5_Update(&context, k_ipad, 64); /* start with inner pad */
MD5_Update(&context, text, text_len); /* then text of datagram */
MD5_Final(digest, &context); /* finish up 1st pass */
/*
* perform outer MD5
*/
MD5_Init(&context); /* init context for 2nd
* pass */
MD5_Update(&context, k_opad, 64); /* start with outer pad */
MD5_Update(&context, digest, 16); /* then results of 1st
* hash */
MD5_Final(digest, &context); /* finish up 2nd pass */
}
/*
* CRAM-MD5 authentication
*/
int
smtp_auth_md5(int fd, char *login, char *password)
{
unsigned char digest[BUF_SIZE];
char buffer[BUF_SIZE], ascii_digest[33];
char *temp;
int len, i;
static char hextab[] = "0123456789abcdef";
temp = calloc(BUF_SIZE, 1);
memset(buffer, 0, sizeof(buffer));
memset(digest, 0, sizeof(digest));
memset(ascii_digest, 0, sizeof(ascii_digest));
/* Send AUTH command according to RFC 2554 */
send_remote_command(fd, "AUTH CRAM-MD5");
if (read_remote(fd, sizeof(buffer), buffer) != 3) {
syslog(LOG_DEBUG, "smarthost authentication:"
" AUTH cram-md5 not available: %s", neterr);
/* if cram-md5 is not available */
free(temp);
return (-1);
}
/* skip 3 char status + 1 char space */
base64_decode(buffer + 4, temp);
hmac_md5((unsigned char *)temp, strlen(temp),
(unsigned char *)password, strlen(password), digest);
free(temp);
ascii_digest[32] = 0;
for (i = 0; i < 16; i++) {
ascii_digest[2*i] = hextab[digest[i] >> 4];
ascii_digest[2*i+1] = hextab[digest[i] & 15];
}
/* prepare answer */
snprintf(buffer, BUF_SIZE, "%s %s", login, ascii_digest);
/* encode answer */
len = base64_encode(buffer, strlen(buffer), &temp);
if (len < 0) {
syslog(LOG_ERR, "can not encode auth reply: %m");
return (-1);
}
/* send answer */
send_remote_command(fd, "%s", temp);
free(temp);
if (read_remote(fd, 0, NULL) != 2) {
syslog(LOG_WARNING, "remote delivery deferred:"
" AUTH cram-md5 failed: %s", neterr);
return (-2);
}
return (0);
}