/* * Copyright (c) 2008 The DragonFly Project. All rights reserved. * * This code is derived from software contributed to The DragonFly Project * by Matthias Schmidt , 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 #include #include #include #include #include #include #include #include #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); } static int verify_server_fingerprint(const X509 *cert) { unsigned char fingerprint[EVP_MAX_MD_SIZE] = {0}; unsigned int fingerprint_len = 0; if(!X509_digest(cert, EVP_sha256(), fingerprint, &fingerprint_len)) { syslog(LOG_WARNING, "failed to load fingerprint of server certicate: %s", ssl_errstr()); return (1); } if(fingerprint_len != SHA256_DIGEST_LENGTH) { syslog(LOG_WARNING, "sha256 fingerprint has unexpected length of %d bytes", fingerprint_len); return (1); } if(memcmp(fingerprint, config.fingerprint, SHA256_DIGEST_LENGTH) != 0) { syslog(LOG_WARNING, "fingerprints do not match"); return (1); } syslog(LOG_DEBUG, "successfully verified server certificate fingerprint"); return (0); } int smtp_init_crypto(int fd, int feature, struct smtp_features* features) { 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 & SECURETRANSFER) != 0) && (feature & STARTTLS) != 0) { /* TLS init phase, disable SSL_write */ config.features |= NOSSL; if (perform_server_greeting(fd, features) == 0) { 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); } } } else { syslog(LOG_ERR, "remote delivery deferred: could not perform server greeting: %s", neterr); return (1); } /* 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 != 1) { 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()); return (1); } if(config.fingerprint != NULL && verify_server_fingerprint(cert)) { X509_free(cert); return (1); } 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); }