arm64/uaccess: Enable hardened usercopy

Enables CONFIG_HARDENED_USERCOPY checks on arm64. As done by KASAN in -next,
renames the low-level functions to __arch_copy_*_user() so a static inline
can do additional work before the copy.

Signed-off-by: Kees Cook <keescook@chromium.org>

1 files changed, 22 insertions, 7 deletions

diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
index 9e397a542756..92848b00e3cd 100644
--- a/arch/arm64/include/asm/uaccess.h
+++ b/arch/arm64/include/asm/uaccess.h
@@ -256,24 +256,39 @@ do {									\
 		-EFAULT;						\
 })
 
-extern unsigned long __must_check __copy_from_user(void *to, const void __user *from, unsigned long n);
-extern unsigned long __must_check __copy_to_user(void __user *to, const void *from, unsigned long n);
+extern unsigned long __must_check __arch_copy_from_user(void *to, const void __user *from, unsigned long n);
+extern unsigned long __must_check __arch_copy_to_user(void __user *to, const void *from, unsigned long n);
 extern unsigned long __must_check __copy_in_user(void __user *to, const void __user *from, unsigned long n);
 extern unsigned long __must_check __clear_user(void __user *addr, unsigned long n);
 
+static inline unsigned long __must_check __copy_from_user(void *to, const void __user *from, unsigned long n)
+{
+	check_object_size(to, n, false);
+	return __arch_copy_from_user(to, from, n);
+}
+
+static inline unsigned long __must_check __copy_to_user(void __user *to, const void *from, unsigned long n)
+{
+	check_object_size(from, n, true);
+	return __arch_copy_to_user(to, from, n);
+}
+
 static inline unsigned long __must_check copy_from_user(void *to, const void __user *from, unsigned long n)
 {
-	if (access_ok(VERIFY_READ, from, n))
-		n = __copy_from_user(to, from, n);
-	else /* security hole - plug it */
+	if (access_ok(VERIFY_READ, from, n)) {
+		check_object_size(to, n, false);
+		n = __arch_copy_from_user(to, from, n);
+	} else /* security hole - plug it */
 		memset(to, 0, n);
 	return n;
 }
 
 static inline unsigned long __must_check copy_to_user(void __user *to, const void *from, unsigned long n)
 {
-	if (access_ok(VERIFY_WRITE, to, n))
-		n = __copy_to_user(to, from, n);
+	if (access_ok(VERIFY_WRITE, to, n)) {
+		check_object_size(from, n, true);
+		n = __arch_copy_to_user(to, from, n);
+	}
 	return n;
 }