arm64: kasan: instrument user memory access API

The upstream commit 1771c6e
("x86/kasan: instrument user memory access API") added KASAN instrument to
x86 user memory access API, so added such instrument to ARM64 too.

Define __copy_to/from_user in C in order to add kasan_check_read/write call,
rename assembly implementation to __arch_copy_to/from_user.

Tested by test_kasan module.

Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Yang Shi <yang.shi@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/include/asm/uaccess.h

@@ -21,6 +21,7 @@
 /*
  * User space memory access functions
  */
+#include <linux/kasan-checks.h>
 #include <linux/string.h>
 #include <linux/thread_info.h>
 
@@ -256,24 +257,40 @@ 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)
+{
+	kasan_check_write(to, n);
+	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)
+{
+	kasan_check_read(from, n);
+	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)
 {
+	kasan_check_write(to, n);
+
 	if (access_ok(VERIFY_READ, from, n))
-		n = __copy_from_user(to, from, n);
+		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)
 {
+	kasan_check_read(from, n);
+
 	if (access_ok(VERIFY_WRITE, to, n))
-		n = __copy_to_user(to, from, n);
+		n = __arch_copy_to_user(to, from, n);
 	return n;
 }
 

arch/arm64/kernel/arm64ksyms.c

@@ -34,8 +34,8 @@ EXPORT_SYMBOL(copy_page);
 EXPORT_SYMBOL(clear_page);
 
 	/* user mem (segment) */
-EXPORT_SYMBOL(__copy_from_user);
-EXPORT_SYMBOL(__copy_to_user);
+EXPORT_SYMBOL(__arch_copy_from_user);
+EXPORT_SYMBOL(__arch_copy_to_user);
 EXPORT_SYMBOL(__clear_user);
 EXPORT_SYMBOL(__copy_in_user);
 

arch/arm64/lib/copy_from_user.S

@@ -66,7 +66,7 @@
 	.endm
 
 end	.req	x5
-ENTRY(__copy_from_user)
+ENTRY(__arch_copy_from_user)
 ALTERNATIVE("nop", __stringify(SET_PSTATE_PAN(0)), ARM64_ALT_PAN_NOT_UAO, \
 	    CONFIG_ARM64_PAN)
 	add	end, x0, x2
@@ -75,7 +75,7 @@ ALTERNATIVE("nop", __stringify(SET_PSTATE_PAN(1)), ARM64_ALT_PAN_NOT_UAO, \
 	    CONFIG_ARM64_PAN)
 	mov	x0, #0				// Nothing to copy
 	ret
-ENDPROC(__copy_from_user)
+ENDPROC(__arch_copy_from_user)
 
 	.section .fixup,"ax"
 	.align	2

arch/arm64/lib/copy_to_user.S

@@ -65,7 +65,7 @@
 	.endm
 
 end	.req	x5
-ENTRY(__copy_to_user)
+ENTRY(__arch_copy_to_user)
 ALTERNATIVE("nop", __stringify(SET_PSTATE_PAN(0)), ARM64_ALT_PAN_NOT_UAO, \
 	    CONFIG_ARM64_PAN)
 	add	end, x0, x2
@@ -74,7 +74,7 @@ ALTERNATIVE("nop", __stringify(SET_PSTATE_PAN(1)), ARM64_ALT_PAN_NOT_UAO, \
 	    CONFIG_ARM64_PAN)
 	mov	x0, #0
 	ret
-ENDPROC(__copy_to_user)
+ENDPROC(__arch_copy_to_user)
 
 	.section .fixup,"ax"
 	.align	2