From c5c4ee4d6a9aa5554ad29be79c4ee3e6bd79c70f Mon Sep 17 00:00:00 2001 From: Dirk Engling Date: Fri, 15 Apr 2016 16:27:42 +0200 Subject: Make fingerprint pinning an option --- vchat-ssl.c | 210 +++++++++++++++++++++++++++++++----------------------------- 1 file changed, 109 insertions(+), 101 deletions(-) (limited to 'vchat-ssl.c') diff --git a/vchat-ssl.c b/vchat-ssl.c index ef5b96e..b344d10 100755 --- a/vchat-ssl.c +++ b/vchat-ssl.c @@ -154,8 +154,21 @@ static SSL_CTX * vc_create_sslctx( vc_x509store_t *vc_store ) int vc_connect_ssl( BIO **conn, vc_x509store_t *vc_store ) { - BIO *ssl_conn = NULL; SSL_CTX * ctx = vc_create_sslctx(vc_store); + X509 *peercert = NULL; + BIO *ssl_conn = NULL; + const SSL *sslp = NULL; + const SSL_CIPHER * cipher = NULL; + + /* 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; if( !ctx ) return 1; @@ -163,112 +176,107 @@ int vc_connect_ssl( BIO **conn, vc_x509store_t *vc_store ) ssl_conn = BIO_new_ssl(ctx, 1); SSL_CTX_free(ctx); - if( ssl_conn ) { - BIO_push( ssl_conn, *conn ); - *conn = ssl_conn; - fflush(stdout); - - if( BIO_do_handshake( *conn ) > 0 ) { - /* Show information about cipher used */ - const SSL *sslp = NULL; - const SSL_CIPHER * cipher = NULL; - - /* Get cipher object */ - BIO_get_ssl(ssl_conn, &sslp); - if (sslp) - 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); - } + if( !ssl_conn ) + goto ssl_error; + + BIO_push( ssl_conn, *conn ); + *conn = ssl_conn; + fflush(stdout); + + if( BIO_do_handshake( *conn ) <= 0 ) + goto ssl_error; + + /* Show information about cipher used */ + /* Get cipher object */ + BIO_get_ssl(ssl_conn, &sslp); + if (sslp) + 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 */ - if (sslp) { - long result = SSL_get_verify_result(sslp); -#if 1 == 1 - if (result == X509_V_OK) { + /* Accept being connected, _if_ verification passed */ + if (!sslp) + goto ssl_error; + + 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(nf, "%02X:", fingerprint_bin[j]); + assert ( fp > fingerprint ); + fp[-1] = 0; + snprintf(tmpstr, TMPSTRSIZE, "[SSL FINGERPRINT ] from server: %s", fingerprint); + writecf(FS_SERV, tmpstr); + + /* we don't need the peercert anymore */ + X509_free(peercert); + + /* If verify of x509 chain was requested, do the check here */ + result = SSL_get_verify_result(sslp); + if (result != X509_V_OK && !getintoption(CF_IGNSSL) ) + goto ssl_error; + + if (result != X509_V_OK) + writecf(FS_ERR, "[SSL VERIFY ERROR ] FAILURE IGNORED!!!"); + + /* verify fingerprint */ + if (getintoption(CF_PIN_FINGERPRINT)) { + + 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; - } else if (getintoption(CF_IGNSSL)) { - writecf(FS_ERR, "[SSL VERIFY ERROR ] FAILURE IGNORED!!!"); - return 0; - } -#else - /* show & verify fingerprint */ - if ((result == X509_V_OK) || getintoption(CF_IGNSSL)) { - X509 *peercert = SSL_get_peer_certificate(sslp); - - /* FIXME: this IS bad code */ - char new_fingerprint[TMPSTRSIZE]; - char old_fingerprint[TMPSTRSIZE]; - FILE *fingerprint_file = NULL; - - unsigned int fingerprint_len; - unsigned char fingerprint_bin[EVP_MAX_MD_SIZE]; - - /* 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)) { - int j; - assert ( ( fingerprint_len > 1 ) && (fingerprint_len * 3 < TMPSTRSIZE )); - char * nf = new_fingerprint; - for (j=0; j<(int)fingerprint_len; j++) - nf += snprintf(nf, 4, "%02X:", fingerprint_bin[j]); - assert ( nf > new_fingerprint ); - nf[-1] = 0; - snprintf(tmpstr, TMPSTRSIZE, "[SSL FINGERPRINT ] from server: %s", new_fingerprint); - writecf(FS_SERV, tmpstr); - } - - // we don't need the peercert anymore - X509_free(peercert); - - fingerprint_file = fopen(tilde_expand(getstroption(CF_FINGERPRINT)), "r"); - if (fingerprint_file) { - char * r = fgets(old_fingerprint, TMPSTRSIZE, fingerprint_file); - fclose(fingerprint_file); - - if (r) { - // chomp - char *nl = strchr(r, '\n'); - if (nl) *nl = 0; - - /* verify fingerprint matches stored version */ - if (!strcmp(new_fingerprint, old_fingerprint)) - return 0; - } - - snprintf(tmpstr, TMPSTRSIZE, "[SSL FINGERPRINT ] from %s: %s", getstroption(CF_FINGERPRINT), r ? old_fingerprint : "" ); - writecf(FS_ERR, tmpstr); - writecf(FS_ERR, "[SSL CONNECT ERROR] Fingerprint mismatch! Server cert updated?"); - return 1; - } else { - /* FIXME: there might be other errors than missing file */ - fingerprint_file = fopen(tilde_expand(getstroption(CF_FINGERPRINT)), "w"); - if (!fingerprint_file) { - snprintf (tmpstr, TMPSTRSIZE, "Can't write fingerprint file, %s.", strerror(errno)); - writecf(FS_ERR, tmpstr); - } else { - fputs(new_fingerprint, fingerprint_file); - fclose(fingerprint_file); - writecf(FS_SERV, "Stored fingerprint."); - return 0; - } - } - } -#endif } + + snprintf(tmpstr, TMPSTRSIZE, "[SSL FINGERPRINT ] from %s: %s", getstroption(CF_FINGERPRINT), r ? old_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; } +ssl_error: snprintf(tmpstr, TMPSTRSIZE, "[SSL CONNECT ERROR] %s", ERR_error_string (ERR_get_error (), NULL)); writecf(FS_ERR, tmpstr); -- cgit v1.2.3