X-Git-Url: https://ruderich.org/simon/gitweb/?a=blobdiff_plain;f=src%2Fverify.c;h=487ad2ede213e1fc266d4e890fc5ce5ee50f1980;hb=193405f1f065a4b1cb6c0a136a9e5965f13993d7;hp=8328432b5e27e0174590c0c69cb97e92fc36c608;hpb=206479fb368638a916ac1c736df3835a1f0c35a5;p=tlsproxy%2Ftlsproxy.git diff --git a/src/verify.c b/src/verify.c index 8328432..487ad2e 100644 --- a/src/verify.c +++ b/src/verify.c @@ -1,7 +1,7 @@ /* * Verify established TLS connections. * - * Copyright (C) 2011 Simon Ruderich + * Copyright (C) 2011-2013 Simon Ruderich * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by @@ -20,15 +20,18 @@ #include "tlsproxy.h" #include "verify.h" -/* errno */ #include -/* gnutls_x509_*() */ + #include +static int get_certificate_path(const char *format, + const char *hostname, char *buffer, size_t size); + + int verify_tls_connection(gnutls_session_t session, const char *hostname) { int result; - char path[1024]; + char path[TLSPROXY_MAX_PATH_LENGTH]; size_t size; unsigned int status; @@ -43,7 +46,7 @@ int verify_tls_connection(gnutls_session_t session, const char *hostname) { result = gnutls_certificate_verify_peers2(session, &status); /* Verification failed (!= invalid certificate but worse), no need for any * more checks. */ - if (0 > result) { + if (result < 0) { LOG(LOG_WARNING, "verify_tls_connection(): gnutls_certificate_verify_peers2() failed: %s", gnutls_strerror(result)); @@ -62,7 +65,7 @@ int verify_tls_connection(gnutls_session_t session, const char *hostname) { /* We only handle X509 certificates for now. Let validation fail to * prevent an attacker from changing the certificate type to prevent * detection. */ - if (GNUTLS_CRT_X509 != gnutls_certificate_type_get(session)) { + if (gnutls_certificate_type_get(session) != GNUTLS_CRT_X509) { LOG(LOG_WARNING, "verify_tls_connection(): no X509 server certificate"); return -1; @@ -70,7 +73,8 @@ int verify_tls_connection(gnutls_session_t session, const char *hostname) { /* Get server certificate. */ - if (0 > (result = gnutls_x509_crt_init(&cert))) { + result = gnutls_x509_crt_init(&cert); + if (result < 0) { LOG(LOG_WARNING, "verify_tls_connection(): gnutls_x509_crt_init() failed: %s", gnutls_strerror(result)); @@ -78,15 +82,15 @@ int verify_tls_connection(gnutls_session_t session, const char *hostname) { } cert_list = gnutls_certificate_get_peers(session, &cert_list_size); - if (NULL == cert_list) { + if (cert_list == NULL) { LOG(LOG_WARNING, "verify_tls_connection(): gnutls_certificate_get_peers() failed"); gnutls_x509_crt_deinit(cert); return -1; } - if (0 > (result = gnutls_x509_crt_import(cert, &cert_list[0], - GNUTLS_X509_FMT_DER))) { + result = gnutls_x509_crt_import(cert, &cert_list[0], GNUTLS_X509_FMT_DER); + if (result < 0) { LOG(LOG_WARNING, "verify_tls_connection(): gnutls_x509_crt_import() failed: %s", gnutls_strerror(result)); @@ -99,7 +103,7 @@ int verify_tls_connection(gnutls_session_t session, const char *hostname) { size = sizeof(server_cert); result = gnutls_x509_crt_export(cert, GNUTLS_X509_FMT_PEM, server_cert, &size); - if (GNUTLS_E_SUCCESS != result) { + if (result != GNUTLS_E_SUCCESS) { LOG(LOG_WARNING, "verify_tls_connection(): gnutls_x509_crt_export() failed: %s", gnutls_strerror(result)); @@ -110,7 +114,7 @@ int verify_tls_connection(gnutls_session_t session, const char *hostname) { gnutls_x509_crt_deinit(cert); /* Open stored server certificate file. */ - if (0 != server_certificate_path(&file, hostname, path, sizeof(path))) { + if (server_certificate_file(&file, hostname, path, sizeof(path)) != 0) { LOG(LOG_DEBUG, "server certificate:\n%s", server_cert); return -1; } @@ -118,10 +122,10 @@ int verify_tls_connection(gnutls_session_t session, const char *hostname) { size = 1; /* '\0' */ stored_cert[0] = '\0'; /* for strcat() */ - while (NULL != fgets(buffer, sizeof(buffer), file)) { + while (fgets(buffer, sizeof(buffer), file) != NULL) { size += strlen(buffer); /* Make sure the buffer is big enough. */ - if (sizeof(stored_cert) <= size) { + if (size >= sizeof(stored_cert)) { LOG(LOG_WARNING, "verify_tls_connection(): '%s' too big", path); fclose(file); @@ -143,7 +147,7 @@ int verify_tls_connection(gnutls_session_t session, const char *hostname) { fclose(file); /* Check if the server certificate matches our stored certificate. */ - if (0 != strcmp(stored_cert, server_cert)) { + if (strcmp(stored_cert, server_cert)) { LOG(LOG_ERROR, "verify_tls_connection(): server certificate changed!", path, strerror(errno)); @@ -152,33 +156,82 @@ int verify_tls_connection(gnutls_session_t session, const char *hostname) { return -2; } + /* Check that the proxy certificate file exists and is readable for this + * domain. This ensures we send an "invalid" certificate even if the proxy + * certificate doesn't exist. */ + if (proxy_certificate_path(hostname, path, sizeof(path)) != 0) { + return -1; + } + file = fopen(path, "r"); + if (file == NULL) { + LOG(LOG_WARNING, + "verify_tls_connection(): proxy certificate doesn't exist: '%s'", + path); + return -1; + } + fclose(file); + return 0; } -int server_certificate_path(FILE **file, const char *hostname, - char *path, size_t size) { + +static int get_certificate_path(const char *format, + const char *hostname, char *buffer, size_t size) { + int result; + /* Hostname too long. */ - if (size - strlen(STORED_SERVER_CERT_FORMAT) <= strlen(hostname)) { + if (size - strlen(format) <= strlen(hostname)) { LOG(LOG_WARNING, - "server_certificate_path(): hostname too long: '%s'", + "get_certificate_path(): hostname too long: '%s'", hostname); return -1; } /* Try to prevent path traversals in hostnames. */ - if (NULL != strstr(hostname, "..")) { + if (strstr(hostname, "..") != NULL) { LOG(LOG_WARNING, - "server_certificate_path(): possible path traversal: '%s'", + "get_certificate_path(): possible path traversal: '%s'", hostname); return -1; } - snprintf(path, size, STORED_SERVER_CERT_FORMAT, hostname); + /* Safe as format is no user input. */ + result = snprintf(buffer, size, format, hostname); + if (result < 0) { + LOG_PERROR(LOG_ERROR, "get_certificate_path(): snprintf failed"); + return -1; + } else if ((size_t)result >= size) { + LOG(LOG_ERROR, "get_certificate_path(): snprintf buffer too short"); + return -1; + } + + return 0; +} + +int proxy_certificate_path(const char *hostname, char *path, size_t size) { + return get_certificate_path(PROXY_SERVER_CERT_FORMAT, + hostname, path, size); +} + +int server_certificate_file(FILE **file, const char *hostname, + char *path, size_t size) { + if (get_certificate_path(STORED_SERVER_CERT_FORMAT, + hostname, path, size) != 0) { + LOG_PERROR(LOG_ERROR, + "server_certificate_file(): failed to get path"); + return -1; + } /* Open the stored certificate file. */ *file = fopen(path, "rb"); - if (NULL == *file) { - LOG(global_passthrough_unknown ? LOG_DEBUG : LOG_WARNING, - "server_certificate_path(): failed to open '%s': %s", - path, strerror(errno)); + if (*file == NULL) { + if (global_passthrough_unknown) { + LOG(LOG_DEBUG, + "server_certificate_file(): failed to open '%s': %s", + path, strerror(errno)); + } else { + LOG(LOG_WARNING, + "server_certificate_file(): failed to open '%s': %s", + path, strerror(errno)); + } /* Couldn't open the file, special case. */ return -2; }