From f911b3f69b0a8296918a06d02eb5144bb4cd8a06 Mon Sep 17 00:00:00 2001 From: Lev Stipakov Date: Fri, 19 Nov 2021 03:55:48 +0200 Subject: [PATCH] Load OpenSSL config on Windows from trusted location Commits - 92535b6 ("contrib/vcpkg-ports: add openssl port with --no-autoload-config option set (CVE-2121-3606)") - 447cfb4 ("crypto_openssl.c: disable explicit initialization on Windows (CVE-2121-3606)") disabled OpenSSL config loading functionality, which could be exploited by loading config from untrusted locations. This feature might be useful for some users. This brings it back and sets OpenSSL enviroment variables OPENSSL_CONF, OPENSSL_ENGINES, OPENSSL_MODULES which are used to load config, engines and modules, to a trusted location. The location is constructed based on installation path, read from registry on startup. If installation path cannot be read, Windows\System32 is used as a fallback. While on it, remove unused "bool impersonate_as_system();" declaration. Trac: #1296 Signed-off-by: Lev Stipakov Acked-by: Selva Nair Message-Id: <20211119015548.687-1-lstipakov@gmail.com> URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg23248.html Signed-off-by: Gert Doering (cherry picked from commit 23e6aaef149bd31a7e80af28ee1e3658d2810d4f) --- .../vcpkg-triplets/arm64-windows-ovpn.cmake | 2 - contrib/vcpkg-triplets/x64-windows-ovpn.cmake | 2 - contrib/vcpkg-triplets/x86-windows-ovpn.cmake | 2 - src/openvpn/buffer.c | 23 ----- src/openvpn/buffer.h | 16 ---- src/openvpn/crypto_openssl.c | 2 - src/openvpn/win32.c | 88 +++++++++++++++++++ src/openvpn/win32.h | 8 +- 8 files changed, 95 insertions(+), 48 deletions(-) diff --git a/contrib/vcpkg-triplets/arm64-windows-ovpn.cmake b/contrib/vcpkg-triplets/arm64-windows-ovpn.cmake index 89f6a2795..dd3c6c0a6 100644 --- a/contrib/vcpkg-triplets/arm64-windows-ovpn.cmake +++ b/contrib/vcpkg-triplets/arm64-windows-ovpn.cmake @@ -5,5 +5,3 @@ set(VCPKG_LIBRARY_LINKAGE dynamic) if(PORT STREQUAL "lz4") set(VCPKG_LIBRARY_LINKAGE static) endif() - -set(OPENSSL_NO_AUTOLOAD_CONFIG ON) diff --git a/contrib/vcpkg-triplets/x64-windows-ovpn.cmake b/contrib/vcpkg-triplets/x64-windows-ovpn.cmake index d860eed63..7036ed2d4 100644 --- a/contrib/vcpkg-triplets/x64-windows-ovpn.cmake +++ b/contrib/vcpkg-triplets/x64-windows-ovpn.cmake @@ -5,5 +5,3 @@ set(VCPKG_LIBRARY_LINKAGE dynamic) if(PORT STREQUAL "lz4") set(VCPKG_LIBRARY_LINKAGE static) endif() - -set(OPENSSL_NO_AUTOLOAD_CONFIG ON) diff --git a/contrib/vcpkg-triplets/x86-windows-ovpn.cmake b/contrib/vcpkg-triplets/x86-windows-ovpn.cmake index c1ea6ef33..7d3bf340b 100644 --- a/contrib/vcpkg-triplets/x86-windows-ovpn.cmake +++ b/contrib/vcpkg-triplets/x86-windows-ovpn.cmake @@ -5,5 +5,3 @@ set(VCPKG_LIBRARY_LINKAGE dynamic) if(PORT STREQUAL "lz4") set(VCPKG_LIBRARY_LINKAGE static) endif() - -set(OPENSSL_NO_AUTOLOAD_CONFIG ON) diff --git a/src/openvpn/buffer.c b/src/openvpn/buffer.c index c82d3d4d6..54e758afa 100644 --- a/src/openvpn/buffer.c +++ b/src/openvpn/buffer.c @@ -310,29 +310,6 @@ openvpn_snprintf(char *str, size_t size, const char *format, ...) return (len >= 0 && len < size); } -/* - * openvpn_swprintf() is currently only used by Windows code paths - * and when enabled for all platforms it will currently break older - * OpenBSD versions lacking vswprintf(3) support in their libc. - */ - -#ifdef _WIN32 -bool -openvpn_swprintf(wchar_t *const str, const size_t size, const wchar_t *const format, ...) -{ - va_list arglist; - int len = -1; - if (size > 0) - { - va_start(arglist, format); - len = vswprintf(str, size, format, arglist); - va_end(arglist); - str[size - 1] = L'\0'; - } - return (len >= 0 && len < size); -} -#endif - /* * write a string to the end of a buffer that was * truncated by buf_printf diff --git a/src/openvpn/buffer.h b/src/openvpn/buffer.h index fc7909b7b..1a795d27f 100644 --- a/src/openvpn/buffer.h +++ b/src/openvpn/buffer.h @@ -449,22 +449,6 @@ __attribute__ ((format(__printf__, 3, 4))) ; -#ifdef _WIN32 -/* - * Like swprintf but guarantees null termination for size > 0 - * - * This is under #ifdef because only Windows-specific code in tun.c - * uses this function and its implementation breaks OpenBSD <= 4.9 - */ -bool -openvpn_swprintf(wchar_t *const str, const size_t size, const wchar_t *const format, ...); - -/* - * Unlike in openvpn_snprintf, we cannot use format attributes since - * GCC doesn't support wprintf as archetype. - */ -#endif - /* * remove/add trailing characters */ diff --git a/src/openvpn/crypto_openssl.c b/src/openvpn/crypto_openssl.c index c9dc9d0ad..ef520928f 100644 --- a/src/openvpn/crypto_openssl.c +++ b/src/openvpn/crypto_openssl.c @@ -154,13 +154,11 @@ crypto_init_lib_engine(const char *engine_name) void crypto_init_lib(void) { -#ifndef _WIN32 #if (OPENSSL_VERSION_NUMBER >= 0x10100000L) OPENSSL_init_crypto(OPENSSL_INIT_LOAD_CONFIG, NULL); #else OPENSSL_config(NULL); #endif -#endif /* _WIN32 */ /* * If you build the OpenSSL library and OpenVPN with * CRYPTO_MDEBUG, you will get a listing of OpenSSL diff --git a/src/openvpn/win32.c b/src/openvpn/win32.c index 6cff17b23..920a3b378 100644 --- a/src/openvpn/win32.c +++ b/src/openvpn/win32.c @@ -101,6 +101,12 @@ struct semaphore netcmd_semaphore; /* GLOBAL */ */ static char *win_sys_path = NULL; /* GLOBAL */ +/** + * Set OpenSSL environment variables to a safe directory + */ +static void +set_openssl_env_vars(); + void init_win32(void) { @@ -110,6 +116,8 @@ init_win32(void) } window_title_clear(&window_title); win32_signal_clear(&win32_signal); + + set_openssl_env_vars(); } void @@ -1509,4 +1517,84 @@ send_msg_iservice(HANDLE pipe, const void *data, size_t size, return ret; } +bool +openvpn_swprintf(wchar_t *const str, const size_t size, const wchar_t *const format, ...) +{ + va_list arglist; + int len = -1; + if (size > 0) + { + va_start(arglist, format); + len = vswprintf(str, size, format, arglist); + va_end(arglist); + str[size - 1] = L'\0'; + } + return (len >= 0 && len < size); +} + +static BOOL +get_install_path(WCHAR *path, DWORD size) +{ + WCHAR reg_path[256]; + HKEY key; + BOOL res = FALSE; + openvpn_swprintf(reg_path, _countof(reg_path), L"SOFTWARE\\" PACKAGE_NAME); + + LONG status = RegOpenKeyExW(HKEY_LOCAL_MACHINE, reg_path, 0, KEY_READ, &key); + if (status != ERROR_SUCCESS) + { + return res; + } + + /* The default value of REG_KEY is the install path */ + status = RegGetValueW(key, NULL, NULL, RRF_RT_REG_SZ, NULL, (LPBYTE)path, &size); + res = status == ERROR_SUCCESS; + + RegCloseKey(key); + + return res; +} + +static void +set_openssl_env_vars() +{ + const WCHAR *ssl_fallback_dir = L"C:\\Windows\\System32"; + + WCHAR install_path[MAX_PATH] = { 0 }; + if (!get_install_path(install_path, _countof(install_path))) + { + /* if we cannot find installation path from the registry, + * use Windows directory as a fallback + */ + openvpn_swprintf(install_path, _countof(install_path), L"%ls", ssl_fallback_dir); + } + + if ((install_path[wcslen(install_path) - 1]) == L'\\') + { + install_path[wcslen(install_path) - 1] = L'\0'; + } + + static struct { + WCHAR *name; + WCHAR *value; + } ossl_env[] = { + {L"OPENSSL_CONF", L"openssl.cnf"}, + {L"OPENSSL_ENGINES", L"engines"}, + {L"OPENSSL_MODULES", L"modules"} + }; + + for (size_t i = 0; i < SIZE(ossl_env); ++i) + { + size_t size = 0; + + _wgetenv_s(&size, NULL, 0, ossl_env[i].name); + if (size == 0) + { + WCHAR val[MAX_PATH] = {0}; + openvpn_swprintf(val, _countof(val), L"%ls\\ssl\\%ls", install_path, ossl_env[i].value); + _wputenv_s(ossl_env[i].name, val); + } + } +} + #endif /* ifdef _WIN32 */ diff --git a/src/openvpn/win32.h b/src/openvpn/win32.h index 5d3371a03..5c3bcc37c 100644 --- a/src/openvpn/win32.h +++ b/src/openvpn/win32.h @@ -327,7 +327,13 @@ bool send_msg_iservice(HANDLE pipe, const void *data, size_t size, int openvpn_execve(const struct argv *a, const struct env_set *es, const unsigned int flags); -bool impersonate_as_system(); +/* + * openvpn_swprintf() is currently only used by Windows code paths + * and when enabled for all platforms it will currently break older + * OpenBSD versions lacking vswprintf(3) support in their libc. + */ +bool +openvpn_swprintf(wchar_t *const str, const size_t size, const wchar_t *const format, ...); #endif /* ifndef OPENVPN_WIN32_H */ #endif /* ifdef _WIN32 */ -- 2.47.2