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Message-Id: <20220920192202.190793-4-keescook@chromium.org>
Date: Tue, 20 Sep 2022 12:22:01 -0700
From: Kees Cook <keescook@...omium.org>
To: linux-hardening@...r.kernel.org
Cc: Kees Cook <keescook@...omium.org>,
Nathan Chancellor <nathan@...nel.org>,
Nick Desaulniers <ndesaulniers@...gle.com>,
Tom Rix <trix@...hat.com>, llvm@...ts.linux.dev,
Siddhesh Poyarekar <siddhesh@...plt.org>,
Arnd Bergmann <arnd@...db.de>, Juergen Gross <jgross@...e.com>,
Boris Ostrovsky <boris.ostrovsky@...cle.com>,
Miguel Ojeda <ojeda@...nel.org>, linux-kernel@...r.kernel.org
Subject: [PATCH 3/4] fortify: Convert to struct vs member helpers
In preparation for adding support for __builtin_dynamic_object_size(),
wrap each instance of __builtin_object_size(p, N) with either the new
__struct_size(p) as __bos(p, 0), or __member_size(p) as __bos(p, 1).
This will allow us to replace the definitions with __bdos() next.
There are no binary differences from this change.
Cc: Nathan Chancellor <nathan@...nel.org>
Cc: Nick Desaulniers <ndesaulniers@...gle.com>
Cc: Tom Rix <trix@...hat.com>
Cc: linux-hardening@...r.kernel.org
Cc: llvm@...ts.linux.dev
Signed-off-by: Kees Cook <keescook@...omium.org>
---
include/linux/fortify-string.h | 68 +++++++++++++++++-----------------
1 file changed, 35 insertions(+), 33 deletions(-)
diff --git a/include/linux/fortify-string.h b/include/linux/fortify-string.h
index 71c0a432c638..3f1178584d7b 100644
--- a/include/linux/fortify-string.h
+++ b/include/linux/fortify-string.h
@@ -20,7 +20,7 @@ void __write_overflow_field(size_t avail, size_t wanted) __compiletime_warning("
({ \
unsigned char *__p = (unsigned char *)(p); \
size_t __ret = SIZE_MAX; \
- size_t __p_size = __builtin_object_size(p, 1); \
+ size_t __p_size = __member_size(p); \
if (__p_size != SIZE_MAX && \
__builtin_constant_p(*__p)) { \
size_t __p_len = __p_size - 1; \
@@ -72,13 +72,15 @@ extern char *__underlying_strncpy(char *p, const char *q, __kernel_size_t size)
__underlying_memcpy(dst, src, bytes)
/*
- * Clang's use of __builtin_object_size() within inlines needs hinting via
- * __pass_object_size(). The preference is to only ever use type 1 (member
+ * Clang's use of __builtin_*object_size() within inlines needs hinting via
+ * __pass_*object_size(). The preference is to only ever use type 1 (member
* size, rather than struct size), but there remain some stragglers using
* type 0 that will be converted in the future.
*/
-#define POS __pass_object_size(1)
-#define POS0 __pass_object_size(0)
+#define POS __pass_object_size(1)
+#define POS0 __pass_object_size(0)
+#define __struct_size(p) __builtin_object_size(p, 0)
+#define __member_size(p) __builtin_object_size(p, 1)
#define __compiletime_lessthan(bounds, length) ( \
__builtin_constant_p(length) && \
@@ -121,7 +123,7 @@ extern char *__underlying_strncpy(char *p, const char *q, __kernel_size_t size)
__FORTIFY_INLINE __diagnose_as(__builtin_strncpy, 1, 2, 3)
char *strncpy(char * const POS p, const char *q, __kernel_size_t size)
{
- size_t p_size = __builtin_object_size(p, 1);
+ size_t p_size = __member_size(p);
if (__compiletime_lessthan(p_size, size))
__write_overflow();
@@ -133,7 +135,7 @@ char *strncpy(char * const POS p, const char *q, __kernel_size_t size)
__FORTIFY_INLINE __diagnose_as(__builtin_strcat, 1, 2)
char *strcat(char * const POS p, const char *q)
{
- size_t p_size = __builtin_object_size(p, 1);
+ size_t p_size = __member_size(p);
if (p_size == SIZE_MAX)
return __underlying_strcat(p, q);
@@ -145,7 +147,7 @@ char *strcat(char * const POS p, const char *q)
extern __kernel_size_t __real_strnlen(const char *, __kernel_size_t) __RENAME(strnlen);
__FORTIFY_INLINE __kernel_size_t strnlen(const char * const POS p, __kernel_size_t maxlen)
{
- size_t p_size = __builtin_object_size(p, 1);
+ size_t p_size = __member_size(p);
size_t p_len = __compiletime_strlen(p);
size_t ret;
@@ -175,7 +177,7 @@ __FORTIFY_INLINE __diagnose_as(__builtin_strlen, 1)
__kernel_size_t __fortify_strlen(const char * const POS p)
{
__kernel_size_t ret;
- size_t p_size = __builtin_object_size(p, 1);
+ size_t p_size = __member_size(p);
/* Give up if we don't know how large p is. */
if (p_size == SIZE_MAX)
@@ -190,8 +192,8 @@ __kernel_size_t __fortify_strlen(const char * const POS p)
extern size_t __real_strlcpy(char *, const char *, size_t) __RENAME(strlcpy);
__FORTIFY_INLINE size_t strlcpy(char * const POS p, const char * const POS q, size_t size)
{
- size_t p_size = __builtin_object_size(p, 1);
- size_t q_size = __builtin_object_size(q, 1);
+ size_t p_size = __member_size(p);
+ size_t q_size = __member_size(q);
size_t q_len; /* Full count of source string length. */
size_t len; /* Count of characters going into destination. */
@@ -219,8 +221,8 @@ __FORTIFY_INLINE ssize_t strscpy(char * const POS p, const char * const POS q, s
{
size_t len;
/* Use string size rather than possible enclosing struct size. */
- size_t p_size = __builtin_object_size(p, 1);
- size_t q_size = __builtin_object_size(q, 1);
+ size_t p_size = __member_size(p);
+ size_t q_size = __member_size(q);
/* If we cannot get size of p and q default to call strscpy. */
if (p_size == SIZE_MAX && q_size == SIZE_MAX)
@@ -265,8 +267,8 @@ __FORTIFY_INLINE __diagnose_as(__builtin_strncat, 1, 2, 3)
char *strncat(char * const POS p, const char * const POS q, __kernel_size_t count)
{
size_t p_len, copy_len;
- size_t p_size = __builtin_object_size(p, 1);
- size_t q_size = __builtin_object_size(q, 1);
+ size_t p_size = __member_size(p);
+ size_t q_size = __member_size(q);
if (p_size == SIZE_MAX && q_size == SIZE_MAX)
return __underlying_strncat(p, q, count);
@@ -324,11 +326,11 @@ __FORTIFY_INLINE void fortify_memset_chk(__kernel_size_t size,
})
/*
- * __builtin_object_size() must be captured here to avoid evaluating argument
- * side-effects further into the macro layers.
+ * __struct_size() vs __member_size() must be captured here to avoid
+ * evaluating argument side-effects further into the macro layers.
*/
#define memset(p, c, s) __fortify_memset_chk(p, c, s, \
- __builtin_object_size(p, 0), __builtin_object_size(p, 1))
+ __struct_size(p), __member_size(p))
/*
* To make sure the compiler can enforce protection against buffer overflows,
@@ -421,7 +423,7 @@ __FORTIFY_INLINE bool fortify_memcpy_chk(__kernel_size_t size,
* fake flexible arrays, until they are all converted to
* proper flexible arrays.
*
- * The implementation of __builtin_object_size() behaves
+ * The implementation of __builtin_*object_size() behaves
* like sizeof() when not directly referencing a flexible
* array member, which means there will be many bounds checks
* that will appear at run-time, without a way for them to be
@@ -487,22 +489,22 @@ __FORTIFY_INLINE bool fortify_memcpy_chk(__kernel_size_t size,
*/
/*
- * __builtin_object_size() must be captured here to avoid evaluating argument
- * side-effects further into the macro layers.
+ * __struct_size() vs __member_size() must be captured here to avoid
+ * evaluating argument side-effects further into the macro layers.
*/
#define memcpy(p, q, s) __fortify_memcpy_chk(p, q, s, \
- __builtin_object_size(p, 0), __builtin_object_size(q, 0), \
- __builtin_object_size(p, 1), __builtin_object_size(q, 1), \
+ __struct_size(p), __struct_size(q), \
+ __member_size(p), __member_size(q), \
memcpy)
#define memmove(p, q, s) __fortify_memcpy_chk(p, q, s, \
- __builtin_object_size(p, 0), __builtin_object_size(q, 0), \
- __builtin_object_size(p, 1), __builtin_object_size(q, 1), \
+ __struct_size(p), __struct_size(q), \
+ __member_size(p), __member_size(q), \
memmove)
extern void *__real_memscan(void *, int, __kernel_size_t) __RENAME(memscan);
__FORTIFY_INLINE void *memscan(void * const POS0 p, int c, __kernel_size_t size)
{
- size_t p_size = __builtin_object_size(p, 0);
+ size_t p_size = __struct_size(p);
if (__compiletime_lessthan(p_size, size))
__read_overflow();
@@ -514,8 +516,8 @@ __FORTIFY_INLINE void *memscan(void * const POS0 p, int c, __kernel_size_t size)
__FORTIFY_INLINE __diagnose_as(__builtin_memcmp, 1, 2, 3)
int memcmp(const void * const POS0 p, const void * const POS0 q, __kernel_size_t size)
{
- size_t p_size = __builtin_object_size(p, 0);
- size_t q_size = __builtin_object_size(q, 0);
+ size_t p_size = __struct_size(p);
+ size_t q_size = __struct_size(q);
if (__builtin_constant_p(size)) {
if (__compiletime_lessthan(p_size, size))
@@ -531,7 +533,7 @@ int memcmp(const void * const POS0 p, const void * const POS0 q, __kernel_size_t
__FORTIFY_INLINE __diagnose_as(__builtin_memchr, 1, 2, 3)
void *memchr(const void * const POS0 p, int c, __kernel_size_t size)
{
- size_t p_size = __builtin_object_size(p, 0);
+ size_t p_size = __struct_size(p);
if (__compiletime_lessthan(p_size, size))
__read_overflow();
@@ -543,7 +545,7 @@ void *memchr(const void * const POS0 p, int c, __kernel_size_t size)
void *__real_memchr_inv(const void *s, int c, size_t n) __RENAME(memchr_inv);
__FORTIFY_INLINE void *memchr_inv(const void * const POS0 p, int c, size_t size)
{
- size_t p_size = __builtin_object_size(p, 0);
+ size_t p_size = __struct_size(p);
if (__compiletime_lessthan(p_size, size))
__read_overflow();
@@ -555,7 +557,7 @@ __FORTIFY_INLINE void *memchr_inv(const void * const POS0 p, int c, size_t size)
extern void *__real_kmemdup(const void *src, size_t len, gfp_t gfp) __RENAME(kmemdup);
__FORTIFY_INLINE void *kmemdup(const void * const POS0 p, size_t size, gfp_t gfp)
{
- size_t p_size = __builtin_object_size(p, 0);
+ size_t p_size = __struct_size(p);
if (__compiletime_lessthan(p_size, size))
__read_overflow();
@@ -568,8 +570,8 @@ __FORTIFY_INLINE void *kmemdup(const void * const POS0 p, size_t size, gfp_t gfp
__FORTIFY_INLINE __diagnose_as(__builtin_strcpy, 1, 2)
char *strcpy(char * const POS p, const char * const POS q)
{
- size_t p_size = __builtin_object_size(p, 1);
- size_t q_size = __builtin_object_size(q, 1);
+ size_t p_size = __member_size(p);
+ size_t q_size = __member_size(q);
size_t size;
/* If neither buffer size is known, immediately give up. */
--
2.34.1
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