313 lines
9.0 KiB
C
313 lines
9.0 KiB
C
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/*
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* Copyright (c) 2008 The DragonFly Project. All rights reserved.
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*
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* This code is derived from software contributed to The DragonFly Project
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* by Matthias Schmidt <matthias@dragonflybsd.org>, University of Marburg,
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* Germany.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name of The DragonFly Project nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific, prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <openssl/x509.h>
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#include <openssl/md5.h>
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#include <openssl/ssl.h>
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#include <openssl/err.h>
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#include <openssl/pem.h>
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#include <openssl/rand.h>
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#include <syslog.h>
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#include "dma.h"
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static int
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init_cert_file(SSL_CTX *ctx, const char *path)
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{
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int error;
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/* Load certificate into ctx */
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error = SSL_CTX_use_certificate_chain_file(ctx, path);
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if (error < 1) {
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syslog(LOG_ERR, "SSL: Cannot load certificate `%s': %s", path, ssl_errstr());
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return (-1);
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}
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/* Add private key to ctx */
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error = SSL_CTX_use_PrivateKey_file(ctx, path, SSL_FILETYPE_PEM);
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if (error < 1) {
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syslog(LOG_ERR, "SSL: Cannot load private key `%s': %s", path, ssl_errstr());
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return (-1);
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}
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/*
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* Check the consistency of a private key with the corresponding
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* certificate
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*/
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error = SSL_CTX_check_private_key(ctx);
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if (error < 1) {
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syslog(LOG_ERR, "SSL: Cannot check private key: %s", ssl_errstr());
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return (-1);
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}
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return (0);
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}
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int
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smtp_init_crypto(int fd, int feature)
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{
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SSL_CTX *ctx = NULL;
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#if (OPENSSL_VERSION_NUMBER >= 0x00909000L)
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const SSL_METHOD *meth = NULL;
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#else
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SSL_METHOD *meth = NULL;
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#endif
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X509 *cert;
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int error;
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/* XXX clean up on error/close */
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/* Init SSL library */
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SSL_library_init();
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SSL_load_error_strings();
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meth = TLSv1_client_method();
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ctx = SSL_CTX_new(meth);
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if (ctx == NULL) {
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syslog(LOG_WARNING, "remote delivery deferred: SSL init failed: %s", ssl_errstr());
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return (1);
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}
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/* User supplied a certificate */
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if (config.certfile != NULL) {
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error = init_cert_file(ctx, config.certfile);
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if (error) {
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syslog(LOG_WARNING, "remote delivery deferred");
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return (1);
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}
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}
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/*
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* If the user wants STARTTLS, we have to send EHLO here
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*/
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if (((feature & SECURETRANS) != 0) &&
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(feature & STARTTLS) != 0) {
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/* TLS init phase, disable SSL_write */
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config.features |= NOSSL;
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send_remote_command(fd, "EHLO %s", hostname());
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if (read_remote(fd, 0, NULL) == 2) {
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send_remote_command(fd, "STARTTLS");
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if (read_remote(fd, 0, NULL) != 2) {
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if ((feature & TLS_OPP) == 0) {
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syslog(LOG_ERR, "remote delivery deferred: STARTTLS not available: %s", neterr);
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return (1);
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} else {
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syslog(LOG_INFO, "in opportunistic TLS mode, STARTTLS not available: %s", neterr);
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return (0);
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}
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}
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}
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/* End of TLS init phase, enable SSL_write/read */
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config.features &= ~NOSSL;
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}
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config.ssl = SSL_new(ctx);
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if (config.ssl == NULL) {
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syslog(LOG_NOTICE, "remote delivery deferred: SSL struct creation failed: %s",
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ssl_errstr());
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return (1);
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}
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/* Set ssl to work in client mode */
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SSL_set_connect_state(config.ssl);
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/* Set fd for SSL in/output */
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error = SSL_set_fd(config.ssl, fd);
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if (error == 0) {
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syslog(LOG_NOTICE, "remote delivery deferred: SSL set fd failed: %s",
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ssl_errstr());
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return (1);
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}
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/* Open SSL connection */
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error = SSL_connect(config.ssl);
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if (error < 0) {
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syslog(LOG_ERR, "remote delivery deferred: SSL handshake failed fatally: %s",
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ssl_errstr());
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return (1);
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}
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/* Get peer certificate */
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cert = SSL_get_peer_certificate(config.ssl);
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if (cert == NULL) {
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syslog(LOG_WARNING, "remote delivery deferred: Peer did not provide certificate: %s",
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ssl_errstr());
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}
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X509_free(cert);
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return (0);
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}
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/*
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* hmac_md5() taken out of RFC 2104. This RFC was written by H. Krawczyk,
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* M. Bellare and R. Canetti.
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*
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* text pointer to data stream
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* text_len length of data stream
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* key pointer to authentication key
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* key_len length of authentication key
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* digest caller digest to be filled int
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*/
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void
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hmac_md5(unsigned char *text, int text_len, unsigned char *key, int key_len,
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unsigned char* digest)
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{
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MD5_CTX context;
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unsigned char k_ipad[65]; /* inner padding -
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* key XORd with ipad
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*/
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unsigned char k_opad[65]; /* outer padding -
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* key XORd with opad
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*/
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unsigned char tk[16];
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int i;
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/* if key is longer than 64 bytes reset it to key=MD5(key) */
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if (key_len > 64) {
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MD5_CTX tctx;
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MD5_Init(&tctx);
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MD5_Update(&tctx, key, key_len);
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MD5_Final(tk, &tctx);
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key = tk;
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key_len = 16;
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}
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/*
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* the HMAC_MD5 transform looks like:
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*
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* MD5(K XOR opad, MD5(K XOR ipad, text))
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*
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* where K is an n byte key
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* ipad is the byte 0x36 repeated 64 times
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*
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* opad is the byte 0x5c repeated 64 times
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* and text is the data being protected
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*/
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/* start out by storing key in pads */
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bzero( k_ipad, sizeof k_ipad);
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bzero( k_opad, sizeof k_opad);
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bcopy( key, k_ipad, key_len);
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bcopy( key, k_opad, key_len);
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/* XOR key with ipad and opad values */
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for (i=0; i<64; i++) {
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k_ipad[i] ^= 0x36;
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k_opad[i] ^= 0x5c;
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}
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/*
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* perform inner MD5
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*/
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MD5_Init(&context); /* init context for 1st
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* pass */
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MD5_Update(&context, k_ipad, 64); /* start with inner pad */
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MD5_Update(&context, text, text_len); /* then text of datagram */
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MD5_Final(digest, &context); /* finish up 1st pass */
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/*
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* perform outer MD5
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*/
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MD5_Init(&context); /* init context for 2nd
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* pass */
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MD5_Update(&context, k_opad, 64); /* start with outer pad */
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MD5_Update(&context, digest, 16); /* then results of 1st
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* hash */
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MD5_Final(digest, &context); /* finish up 2nd pass */
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}
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/*
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* CRAM-MD5 authentication
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*/
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int
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smtp_auth_md5(int fd, char *login, char *password)
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{
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unsigned char digest[BUF_SIZE];
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char buffer[BUF_SIZE], ascii_digest[33];
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char *temp;
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int len, i;
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static char hextab[] = "0123456789abcdef";
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temp = calloc(BUF_SIZE, 1);
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memset(buffer, 0, sizeof(buffer));
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memset(digest, 0, sizeof(digest));
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memset(ascii_digest, 0, sizeof(ascii_digest));
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/* Send AUTH command according to RFC 2554 */
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send_remote_command(fd, "AUTH CRAM-MD5");
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if (read_remote(fd, sizeof(buffer), buffer) != 3) {
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syslog(LOG_DEBUG, "smarthost authentication:"
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" AUTH cram-md5 not available: %s", neterr);
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/* if cram-md5 is not available */
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free(temp);
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return (-1);
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}
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/* skip 3 char status + 1 char space */
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base64_decode(buffer + 4, temp);
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hmac_md5((unsigned char *)temp, strlen(temp),
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(unsigned char *)password, strlen(password), digest);
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free(temp);
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ascii_digest[32] = 0;
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for (i = 0; i < 16; i++) {
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ascii_digest[2*i] = hextab[digest[i] >> 4];
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ascii_digest[2*i+1] = hextab[digest[i] & 15];
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}
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/* prepare answer */
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snprintf(buffer, BUF_SIZE, "%s %s", login, ascii_digest);
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/* encode answer */
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len = base64_encode(buffer, strlen(buffer), &temp);
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if (len < 0) {
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syslog(LOG_ERR, "can not encode auth reply: %m");
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return (-1);
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}
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/* send answer */
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send_remote_command(fd, "%s", temp);
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free(temp);
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if (read_remote(fd, 0, NULL) != 2) {
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syslog(LOG_WARNING, "remote delivery deferred:"
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" AUTH cram-md5 failed: %s", neterr);
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return (-2);
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}
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return (0);
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}
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