/* * vchat-client - alpha version * vchat-tls.c - handling of SSL connection and X509 certificate * verification * * Copyright (C) 2007 Thorsten Schroeder * * This program is free software. It can be redistributed and/or modified, * provided that this copyright notice is kept intact. This program 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. In no event shall the copyright holder be liable for * any direct, indirect, incidental or special damages arising in any way out * of the use of this software. * */ #include #include #include #include #include #include "vchat.h" #include "vchat-tls.h" const char *vchat_tls_version = "vchat-tls.c $Id$"; const char *vchat_tls_version_external = "Unknown implementation; version unknown"; void vc_cleanup_x509store(vc_x509store_t *store) { free(store->cafile); free(store->capath); free(store->crlfile); free(store->certfile); free(store->keyfile); memset(store, 0, sizeof(vc_x509store_t)); } void vc_x509store_setflags(vc_x509store_t *store, int flags) { store->flags |= flags; } void vc_x509store_clearflags(vc_x509store_t *store, int flags) { store->flags &= ~flags; } void vc_x509store_set_pkeycb(vc_x509store_t *store, vc_askpass_cb_t callback) { store->askpass_callback = callback; } void vc_x509store_setcafile(vc_x509store_t *store, char *file) { free(store->cafile); store->cafile = ( file ? strdup(file) : 0 ); store->flags |= VC_X509S_USE_CAFILE; } void vc_x509store_setcapath(vc_x509store_t *store, char *path) { free(store->capath); store->capath = ( path ? strdup(path) : 0 ); } void vc_x509store_setcrlfile(vc_x509store_t *store, char *file) { free(store->crlfile); store->crlfile = ( file ? strdup(file) : 0 ); } void vc_x509store_setkeyfile(vc_x509store_t *store, char *file) { free(store->keyfile); store->keyfile = ( file ? strdup(file) : 0 ); } void vc_x509store_setcertfile(vc_x509store_t *store, char *file) { free(store->certfile); store->certfile = ( file ? strdup(file) : 0 ); store->flags |= VC_X509S_USE_CERTIFICATE; } //// OPENSSL SPECIFIC #include #include #include #include #include #include #include void vchat_tls_get_version_external() { snprintf(tmpstr, sizeof(tmpstr), "OpenSSL %s with %s", SSLeay_version(SSLEAY_VERSION), SSLeay_version(SSLEAY_CFLAGS)); vchat_tls_version_external = strdup(tmpstr); } /* Helpers to work with vc_x509store_t used by all tls libs */ void vc_init_x509store(vc_x509store_t *store) { static int sslinit; if (!sslinit++) { SSL_library_init (); SSL_load_error_strings(); } memset(store, 0, sizeof(vc_x509store_t)); /* We want to make verifying the peer the default */ store->flags |= VC_X509S_SSL_VERIFY_PEER; } /* connection BIO for openssl */ static BIO *server_conn = NULL; static SSL_CTX * vc_create_sslctx( vc_x509store_t *vc_store ); static int vc_verify_callback(int, X509_STORE_CTX *); static X509_STORE * vc_x509store_create(vc_x509store_t *); static SSL_CTX * vc_create_sslctx( vc_x509store_t *vc_store ) { int flags = 0; /* Explicitly use TLSv1 (or maybe later) */ SSL_CTX *ctx = SSL_CTX_new(TLS_client_method()); X509_STORE *store = vc_x509store_create(vc_store); if (!ctx || !store) { snprintf(tmpstr, sizeof(tmpstr), "CREATE CTX: %s",ERR_error_string (ERR_get_error (), NULL)); writecf(FS_ERR, tmpstr); if (store) X509_STORE_free(store); if (ctx) SSL_CTX_free(ctx); return NULL; } SSL_CTX_set_cert_store(ctx, store); /* Disable some insecure protocols explicitly */ SSL_CTX_set_options(ctx, SSL_OP_ALL | SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3); if (getstroption(CF_CIPHERSUITE)) SSL_CTX_set_cipher_list(ctx, getstroption(CF_CIPHERSUITE)); else SSL_CTX_set_cipher_list(ctx, "ECDHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES256-SHA"); SSL_CTX_set_verify_depth (ctx, getintoption(CF_VERIFYSSL)); if( !(vc_store->flags & VC_X509S_SSL_VERIFY_MASK) ) { writecf(FS_DBG, tmpstr); flags = SSL_VERIFY_NONE; } else { if(vc_store->flags & VC_X509S_SSL_VERIFY_PEER) flags |= SSL_VERIFY_PEER; if(vc_store->flags & VC_X509S_SSL_VERIFY_FAIL_IF_NO_PEER_CERT) flags |= SSL_VERIFY_FAIL_IF_NO_PEER_CERT; if(vc_store->flags & VC_X509S_SSL_VERIFY_CLIENT_ONCE) flags |= SSL_VERIFY_CLIENT_ONCE; } SSL_CTX_set_verify(ctx, flags, vc_verify_callback); if(vc_store->flags & VC_X509S_USE_CERTIFICATE) { int r = 0; if(vc_store->certfile) SSL_CTX_use_certificate_chain_file(ctx, vc_store->certfile); SSL_CTX_set_default_passwd_cb(ctx, vc_store->askpass_callback); if(vc_store->keyfile) r=SSL_CTX_use_PrivateKey_file(ctx, vc_store->keyfile, SSL_FILETYPE_PEM); if( r!=1 || !SSL_CTX_check_private_key(ctx)) { snprintf(tmpstr, sizeof(tmpstr), "CREATE CTX: Load private key failed"); writecf(FS_ERR, tmpstr); SSL_CTX_free(ctx); return NULL; } } SSL_CTX_set_app_data(ctx, vc_store); return(ctx); } int vc_tls_connect( int serverfd, vc_x509store_t *vc_store ) { SSL_CTX * ctx = vc_create_sslctx(vc_store); X509 *peercert = NULL; BIO *ssl_conn = NULL; const SSL *sslp = NULL; const SSL_CIPHER * cipher = NULL; server_conn = BIO_new_socket( serverfd, 1 ); /* To display and check server fingerprint */ char fingerprint[EVP_MAX_MD_SIZE*4]; unsigned char fingerprint_bin[EVP_MAX_MD_SIZE]; unsigned int fingerprint_len; FILE *fingerprint_file = NULL; char * fp = fingerprint; long result, j; if( !ctx ) goto all_errors; ssl_conn = BIO_new_ssl(ctx, 1); SSL_CTX_free(ctx); if( !ssl_conn ) goto ssl_error; BIO_push( ssl_conn, server_conn ); server_conn = ssl_conn; fflush(stdout); if( BIO_do_handshake( server_conn ) <= 0 ) goto ssl_error; /* Show information about cipher used */ /* Get cipher object */ BIO_get_ssl(ssl_conn, &sslp); if (!sslp) goto ssl_error; cipher = SSL_get_current_cipher(sslp); if (cipher) { char cipher_desc[TMPSTRSIZE]; snprintf(tmpstr, TMPSTRSIZE, "[SSL CIPHER ] %s", SSL_CIPHER_description(cipher, cipher_desc, TMPSTRSIZE)); writecf(FS_SERV, tmpstr); } else { snprintf(tmpstr, TMPSTRSIZE, "[SSL ERROR ] Cipher not known / SSL object can't be queried!"); writecf(FS_ERR, tmpstr); } /* Accept being connected, _if_ verification passed */ peercert = SSL_get_peer_certificate(sslp); if (!peercert) goto ssl_error; /* show basic information about peer cert */ snprintf(tmpstr, TMPSTRSIZE, "[SSL SUBJECT ] %s", X509_NAME_oneline(X509_get_subject_name(peercert),0,0)); writecf(FS_SERV, tmpstr); snprintf(tmpstr, TMPSTRSIZE, "[SSL ISSUER ] %s", X509_NAME_oneline(X509_get_issuer_name(peercert),0,0)); writecf(FS_SERV, tmpstr); /* calculate fingerprint */ if (!X509_digest(peercert,EVP_sha1(),fingerprint_bin,&fingerprint_len)) goto ssl_error; assert ( ( fingerprint_len > 1 ) && (fingerprint_len <= EVP_MAX_MD_SIZE )); for (j=0; j<(int)fingerprint_len; j++) fp += sprintf(fp, "%02X:", fingerprint_bin[j]); assert ( fp > fingerprint ); fp[-1] = 0; snprintf(tmpstr, TMPSTRSIZE, "[SSL FINGERPRINT ] %s (from server)", fingerprint); writecf(FS_SERV, tmpstr); /* we don't need the peercert anymore */ X509_free(peercert); /* verify fingerprint */ if (getintoption(CF_PINFINGER)) { fingerprint_file = fopen(tilde_expand(getstroption(CF_FINGERPRINT)), "r"); if (fingerprint_file) { /* Read fingerprint from file */ char old_fingerprint[EVP_MAX_MD_SIZE*4]; char * r = fgets(old_fingerprint, sizeof(old_fingerprint), fingerprint_file); fclose(fingerprint_file); if (r) { /* chomp */ char *nl = strchr(r, '\n'); if (nl) *nl = 0; /* verify fingerprint matches stored version */ if (!strcmp(fingerprint, old_fingerprint)) return 0; } snprintf(tmpstr, TMPSTRSIZE, "[SSL FINGERPRINT ] %s (from %s)", r ? old_fingerprint : "", getstroption(CF_FINGERPRINT)); writecf(FS_ERR, tmpstr); writecf(FS_ERR, "[SSL CONNECT ERROR] Fingerprint mismatch! Server cert updated?"); return 1; } fingerprint_file = fopen(tilde_expand(getstroption(CF_FINGERPRINT)), "w"); if (!fingerprint_file) { snprintf (tmpstr, TMPSTRSIZE, "[WARNING] Can't write fingerprint file, %s.", strerror(errno)); writecf(FS_ERR, tmpstr); } else { fputs(fingerprint, fingerprint_file); fclose(fingerprint_file); writecf(FS_SERV, "Stored fingerprint."); } return 0; } /* If verify of x509 chain was requested, do the check here */ result = SSL_get_verify_result(sslp); if (result == X509_V_OK) return 0; if (getintoption(CF_IGNSSL)) { writecf(FS_ERR, "[SSL VERIFY ERROR ] FAILURE IGNORED!!!"); return 0; } ssl_error: snprintf(tmpstr, TMPSTRSIZE, "[SSL CONNECT ERROR] %s", ERR_error_string (ERR_get_error (), NULL)); writecf(FS_ERR, tmpstr); all_errors: BIO_free_all( server_conn ); server_conn = NULL; return 1; } #define VC_STORE_ERR_EXIT(s) do { \ fprintf(stderr, "[E] SSL_STORE: %s\n", ERR_error_string (ERR_get_error (), NULL)); \ if(s) X509_STORE_free(s); \ return(0); \ } while(0) X509_STORE *vc_x509store_create(vc_x509store_t *vc_store) { X509_STORE *store = NULL; X509_LOOKUP *lookup = NULL; store = X509_STORE_new(); X509_STORE_set_verify_cb_func(store, vc_verify_callback); if( !(lookup = X509_STORE_add_lookup(store, X509_LOOKUP_file())) ) VC_STORE_ERR_EXIT(store); if (!vc_store->cafile) { if( !(vc_store->flags & VC_X509S_USE_CAFILE) ) X509_LOOKUP_load_file(lookup, 0, X509_FILETYPE_DEFAULT); } else if( !X509_LOOKUP_load_file(lookup, vc_store->cafile, X509_FILETYPE_PEM) ) VC_STORE_ERR_EXIT(store); if (vc_store->crlfile) { if( !X509_load_crl_file(lookup, vc_store->crlfile, X509_FILETYPE_PEM) ) VC_STORE_ERR_EXIT(store); X509_STORE_set_flags( store, X509_V_FLAG_CRL_CHECK | X509_V_FLAG_CRL_CHECK_ALL ); } if ( !(lookup = X509_STORE_add_lookup(store, X509_LOOKUP_hash_dir())) ) VC_STORE_ERR_EXIT(store); if ( !vc_store->capath ) { if( !(vc_store->flags & VC_X509S_USE_CAPATH) ) X509_LOOKUP_add_dir(lookup, 0, X509_FILETYPE_DEFAULT); } else if( !X509_LOOKUP_add_dir(lookup, vc_store->capath, X509_FILETYPE_PEM) ) VC_STORE_ERR_EXIT(store); return(store); } int vc_verify_callback(int ok, X509_STORE_CTX *store) { if(!ok) { snprintf(tmpstr, TMPSTRSIZE, "[SSL VERIFY ERROR ] %s", X509_verify_cert_error_string(X509_STORE_CTX_get_error(store))); writecf(FS_ERR, tmpstr); } return (ok | getintoption(CF_IGNSSL)); } ssize_t vc_tls_sendmessage(const void *buf, size_t size) { return BIO_write(server_conn, buf, size); } ssize_t vc_tls_receivemessage(void *buf, size_t size) { ssize_t received = (ssize_t)BIO_read (server_conn, buf, size); if (received != 0) return received; if (BIO_should_retry(server_conn)) return -2; return 0; } void vc_tls_cleanup() { BIO_free_all( server_conn ); server_conn = NULL; }