From: Kees Cook <keescook@chromium.org>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Kees Cook <keescook@chromium.org>,
Ard Biesheuvel <ardb@kernel.org>,
linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org,
clang-built-linux@googlegroups.com
Subject: [PATCH 2/3] lib/test_stackinit: Allow building stand-alone
Date: Fri, 23 Jul 2021 15:19:32 -0700 [thread overview]
Message-ID: <20210723221933.3431999-3-keescook@chromium.org> (raw)
In-Reply-To: <20210723221933.3431999-1-keescook@chromium.org>
Especially now that GCC is developing the -ftrivial-auto-var-init
option[1], it's helpful to have a stand-alone userspace test for stack
variable initialization. Relicense to GPLv2+ (I am the only author),
provide stand-alone kernel macro stubs, and update comments for clarity.
[1] https://gcc.gnu.org/pipermail/gcc-patches/2021-July/575198.html
Signed-off-by: Kees Cook <keescook@chromium.org>
---
lib/test_stackinit.c | 71 ++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 68 insertions(+), 3 deletions(-)
diff --git a/lib/test_stackinit.c b/lib/test_stackinit.c
index 16b1d3a3a497..e2713b639873 100644
--- a/lib/test_stackinit.c
+++ b/lib/test_stackinit.c
@@ -1,8 +1,13 @@
-// SPDX-License-Identifier: GPL-2.0
+// SPDX-License-Identifier: GPL-2.0-or-later
/*
- * Test cases for compiler-based stack variable zeroing via future
- * compiler flags or CONFIG_GCC_PLUGIN_STRUCTLEAK*.
+ * Test cases for compiler-based stack variable zeroing via
+ * -ftrivial-auto-var-init={zero,pattern} or CONFIG_GCC_PLUGIN_STRUCTLEAK*.
+ *
+ * External build example:
+ * clang -O2 -Wall -ftrivial-auto-var-init=pattern \
+ * -o test_stackinit test_stackinit.c
*/
+#ifdef __KERNEL__
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/init.h>
@@ -10,6 +15,62 @@
#include <linux/module.h>
#include <linux/string.h>
+#else
+
+/* Userspace headers. */
+#include <stdio.h>
+#include <stdint.h>
+#include <string.h>
+#include <stdbool.h>
+#include <errno.h>
+
+/* Linux kernel-ism stubs for stand-alone userspace build. */
+#define KBUILD_MODNAME "stackinit"
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#define pr_err(fmt, ...) fprintf(stderr, pr_fmt(fmt), ##__VA_ARGS__)
+#define pr_warn(fmt, ...) fprintf(stderr, pr_fmt(fmt), ##__VA_ARGS__)
+#define pr_info(fmt, ...) fprintf(stdout, pr_fmt(fmt), ##__VA_ARGS__)
+#define __init /**/
+#define __exit /**/
+#define __user /**/
+#define noinline __attribute__((__noinline__))
+#define __aligned(x) __attribute__((__aligned__(x)))
+#ifdef __clang__
+# define __compiletime_error(message) /**/
+#else
+# define __compiletime_error(message) __attribute__((__error__(message)))
+#endif
+#define __compiletime_assert(condition, msg, prefix, suffix) \
+ do { \
+ extern void prefix ## suffix(void) __compiletime_error(msg); \
+ if (!(condition)) \
+ prefix ## suffix(); \
+ } while (0)
+#define _compiletime_assert(condition, msg, prefix, suffix) \
+ __compiletime_assert(condition, msg, prefix, suffix)
+#define compiletime_assert(condition, msg) \
+ _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
+#define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
+#define BUILD_BUG_ON(condition) \
+ BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition)
+typedef uint8_t u8;
+typedef uint16_t u16;
+typedef uint32_t u32;
+typedef uint64_t u64;
+
+#define module_init(func) static int (*do_init)(void) = func
+#define module_exit(func) static void (*do_exit)(void) = func
+#define MODULE_LICENSE(str) int main(void) { \
+ int rc; \
+ /* License: str */ \
+ rc = do_init(); \
+ if (rc == 0) \
+ do_exit(); \
+ return rc; \
+ }
+
+#endif /* __KERNEL__ */
+
/* Exfiltration buffer. */
#define MAX_VAR_SIZE 128
static u8 check_buf[MAX_VAR_SIZE];
@@ -279,6 +340,10 @@ DEFINE_TEST(user, struct test_user, STRUCT, none);
static int noinline __leaf_switch_none(int path, bool fill)
{
switch (path) {
+ /*
+ * This is intentionally unreachable. To silence the
+ * warning, build with -Wno-switch-unreachable
+ */
uint64_t var;
case 1:
--
2.30.2
next prev parent reply other threads:[~2021-07-23 22:20 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-23 22:19 [PATCH 0/3] lib/test_stackinit: Add assigned initializers Kees Cook
2021-07-23 22:19 ` [PATCH 1/3] lib/test_stackinit: Fix static initializer test Kees Cook
2021-07-23 22:19 ` Kees Cook [this message]
2021-07-23 22:19 ` [PATCH 3/3] lib/test_stackinit: Add assigned initializers Kees Cook
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