summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2013-11-12 05:39:08 +0400
committerLinus Torvalds <torvalds@linux-foundation.org>2013-11-12 05:39:08 +0400
commitae795fe760e20a7c6ad0f2cd24fc31afad73f427 (patch)
tree06e1064d5f4f10aa4838c0748773e4328b07e535
parentb7ab6e3d21b17a5b488aeb49bd415a9433b8a79e (diff)
parent7a3d9b0f3abbea957b829cdfff8169872c575642 (diff)
downloadlinux-ae795fe760e20a7c6ad0f2cd24fc31afad73f427.tar.xz
Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 user access changes from Ingo Molnar: "This tree contains two copy_[from/to]_user() build time checking changes/enhancements from Jan Beulich. The desired outcome is to get better compiler warnings with CONFIG_DEBUG_STRICT_USER_COPY_CHECKS=y, to keep people from introducing bugs such as overflows and information leaks" * 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86: Unify copy_to_user() and add size checking to it x86: Unify copy_from_user() size checking
-rw-r--r--arch/x86/include/asm/uaccess.h98
-rw-r--r--arch/x86/include/asm/uaccess_32.h29
-rw-r--r--arch/x86/include/asm/uaccess_64.h28
-rw-r--r--arch/x86/lib/usercopy_32.c8
4 files changed, 101 insertions, 62 deletions
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index 5838fa911aa0..8ec57c07b125 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -542,5 +542,103 @@ extern struct movsl_mask {
# include <asm/uaccess_64.h>
#endif
+unsigned long __must_check _copy_from_user(void *to, const void __user *from,
+ unsigned n);
+unsigned long __must_check _copy_to_user(void __user *to, const void *from,
+ unsigned n);
+
+#ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS
+# define copy_user_diag __compiletime_error
+#else
+# define copy_user_diag __compiletime_warning
+#endif
+
+extern void copy_user_diag("copy_from_user() buffer size is too small")
+copy_from_user_overflow(void);
+extern void copy_user_diag("copy_to_user() buffer size is too small")
+copy_to_user_overflow(void) __asm__("copy_from_user_overflow");
+
+#undef copy_user_diag
+
+#ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS
+
+extern void
+__compiletime_warning("copy_from_user() buffer size is not provably correct")
+__copy_from_user_overflow(void) __asm__("copy_from_user_overflow");
+#define __copy_from_user_overflow(size, count) __copy_from_user_overflow()
+
+extern void
+__compiletime_warning("copy_to_user() buffer size is not provably correct")
+__copy_to_user_overflow(void) __asm__("copy_from_user_overflow");
+#define __copy_to_user_overflow(size, count) __copy_to_user_overflow()
+
+#else
+
+static inline void
+__copy_from_user_overflow(int size, unsigned long count)
+{
+ WARN(1, "Buffer overflow detected (%d < %lu)!\n", size, count);
+}
+
+#define __copy_to_user_overflow __copy_from_user_overflow
+
+#endif
+
+static inline unsigned long __must_check
+copy_from_user(void *to, const void __user *from, unsigned long n)
+{
+ int sz = __compiletime_object_size(to);
+
+ might_fault();
+
+ /*
+ * While we would like to have the compiler do the checking for us
+ * even in the non-constant size case, any false positives there are
+ * a problem (especially when DEBUG_STRICT_USER_COPY_CHECKS, but even
+ * without - the [hopefully] dangerous looking nature of the warning
+ * would make people go look at the respecitive call sites over and
+ * over again just to find that there's no problem).
+ *
+ * And there are cases where it's just not realistic for the compiler
+ * to prove the count to be in range. For example when multiple call
+ * sites of a helper function - perhaps in different source files -
+ * all doing proper range checking, yet the helper function not doing
+ * so again.
+ *
+ * Therefore limit the compile time checking to the constant size
+ * case, and do only runtime checking for non-constant sizes.
+ */
+
+ if (likely(sz < 0 || sz >= n))
+ n = _copy_from_user(to, from, n);
+ else if(__builtin_constant_p(n))
+ copy_from_user_overflow();
+ else
+ __copy_from_user_overflow(sz, n);
+
+ return n;
+}
+
+static inline unsigned long __must_check
+copy_to_user(void __user *to, const void *from, unsigned long n)
+{
+ int sz = __compiletime_object_size(from);
+
+ might_fault();
+
+ /* See the comment in copy_from_user() above. */
+ if (likely(sz < 0 || sz >= n))
+ n = _copy_to_user(to, from, n);
+ else if(__builtin_constant_p(n))
+ copy_to_user_overflow();
+ else
+ __copy_to_user_overflow(sz, n);
+
+ return n;
+}
+
+#undef __copy_from_user_overflow
+#undef __copy_to_user_overflow
+
#endif /* _ASM_X86_UACCESS_H */
diff --git a/arch/x86/include/asm/uaccess_32.h b/arch/x86/include/asm/uaccess_32.h
index 7f760a9f1f61..3c03a5de64d3 100644
--- a/arch/x86/include/asm/uaccess_32.h
+++ b/arch/x86/include/asm/uaccess_32.h
@@ -184,33 +184,4 @@ __copy_from_user_inatomic_nocache(void *to, const void __user *from,
return __copy_from_user_ll_nocache_nozero(to, from, n);
}
-unsigned long __must_check copy_to_user(void __user *to,
- const void *from, unsigned long n);
-unsigned long __must_check _copy_from_user(void *to,
- const void __user *from,
- unsigned long n);
-
-
-extern void copy_from_user_overflow(void)
-#ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS
- __compiletime_error("copy_from_user() buffer size is not provably correct")
-#else
- __compiletime_warning("copy_from_user() buffer size is not provably correct")
-#endif
-;
-
-static inline unsigned long __must_check copy_from_user(void *to,
- const void __user *from,
- unsigned long n)
-{
- int sz = __compiletime_object_size(to);
-
- if (likely(sz == -1 || sz >= n))
- n = _copy_from_user(to, from, n);
- else
- copy_from_user_overflow();
-
- return n;
-}
-
#endif /* _ASM_X86_UACCESS_32_H */
diff --git a/arch/x86/include/asm/uaccess_64.h b/arch/x86/include/asm/uaccess_64.h
index 4f7923dd0007..0acae710fa00 100644
--- a/arch/x86/include/asm/uaccess_64.h
+++ b/arch/x86/include/asm/uaccess_64.h
@@ -46,36 +46,8 @@ copy_user_generic(void *to, const void *from, unsigned len)
}
__must_check unsigned long
-_copy_to_user(void __user *to, const void *from, unsigned len);
-__must_check unsigned long
-_copy_from_user(void *to, const void __user *from, unsigned len);
-__must_check unsigned long
copy_in_user(void __user *to, const void __user *from, unsigned len);
-static inline unsigned long __must_check copy_from_user(void *to,
- const void __user *from,
- unsigned long n)
-{
- int sz = __compiletime_object_size(to);
-
- might_fault();
- if (likely(sz == -1 || sz >= n))
- n = _copy_from_user(to, from, n);
-#ifdef CONFIG_DEBUG_VM
- else
- WARN(1, "Buffer overflow detected!\n");
-#endif
- return n;
-}
-
-static __always_inline __must_check
-int copy_to_user(void __user *dst, const void *src, unsigned size)
-{
- might_fault();
-
- return _copy_to_user(dst, src, size);
-}
-
static __always_inline __must_check
int __copy_from_user(void *dst, const void __user *src, unsigned size)
{
diff --git a/arch/x86/lib/usercopy_32.c b/arch/x86/lib/usercopy_32.c
index 3eb18acd0e40..e2f5e21c03b3 100644
--- a/arch/x86/lib/usercopy_32.c
+++ b/arch/x86/lib/usercopy_32.c
@@ -654,14 +654,13 @@ EXPORT_SYMBOL(__copy_from_user_ll_nocache_nozero);
* Returns number of bytes that could not be copied.
* On success, this will be zero.
*/
-unsigned long
-copy_to_user(void __user *to, const void *from, unsigned long n)
+unsigned long _copy_to_user(void __user *to, const void *from, unsigned n)
{
if (access_ok(VERIFY_WRITE, to, n))
n = __copy_to_user(to, from, n);
return n;
}
-EXPORT_SYMBOL(copy_to_user);
+EXPORT_SYMBOL(_copy_to_user);
/**
* copy_from_user: - Copy a block of data from user space.
@@ -679,8 +678,7 @@ EXPORT_SYMBOL(copy_to_user);
* If some data could not be copied, this function will pad the copied
* data to the requested size using zero bytes.
*/
-unsigned long
-_copy_from_user(void *to, const void __user *from, unsigned long n)
+unsigned long _copy_from_user(void *to, const void __user *from, unsigned n)
{
if (access_ok(VERIFY_READ, from, n))
n = __copy_from_user(to, from, n);