[Openvpn-devel] Load OpenSSL config on Windows from trusted location

Message ID 20211118205229.303-1-lstipakov@gmail.com
State Superseded
Headers show
Series [Openvpn-devel] Load OpenSSL config on Windows from trusted location | expand

Commit Message

Lev Stipakov Nov. 18, 2021, 8:52 p.m. UTC
From: Lev Stipakov <lev@openvpn.net>

Commit 7e33127d5 ("contrib/vcpkg-ports: remove openssl port")
disabled OpenSSL config loading to prevent loading config
from untrusted locations.

Config loading 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 built 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.

Signed-off-by: Lev Stipakov <lev@openvpn.net>
---
 .../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/win32.c                           | 76 +++++++++++++++++++
 src/openvpn/win32.h                           |  8 +-
 6 files changed, 83 insertions(+), 30 deletions(-)

Patch

diff --git a/contrib/vcpkg-triplets/arm64-windows-ovpn.cmake b/contrib/vcpkg-triplets/arm64-windows-ovpn.cmake
index 89f6a279..dd3c6c0a 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 d860eed6..7036ed2d 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 c1ea6ef3..7d3bf340 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 c82d3d4d..54e758af 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/win32.c b/src/openvpn/win32.c
index 6cff17b2..6d169a23 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
+ */
+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 +1517,72 @@  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);
+    }
+
+    WCHAR openssl_cnf[MAX_PATH] = {0};
+    WCHAR openssl_engines[MAX_PATH] = {0};
+    WCHAR openssl_modules[MAX_PATH] = {0};
+
+    openvpn_swprintf(openssl_cnf, _countof(install_path),
+        L"OPENSSL_CONF=%lsssl\\openssl.cnf", install_path);
+    openvpn_swprintf(openssl_engines, _countof(openssl_engines),
+        L"OPENSSL_ENGINES=%lsssl\\engines", install_path);
+    openvpn_swprintf(openssl_modules, _countof(openssl_modules),
+        L"OPENSSL_MODULES=%lsssl\\modules", install_path);
+
+    _wputenv(openssl_cnf);
+    _wputenv(openssl_engines);
+    _wputenv(openssl_modules);
+}
+
 #endif /* ifdef _WIN32 */
diff --git a/src/openvpn/win32.h b/src/openvpn/win32.h
index 5d3371a0..4a992d91 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 */