[v2 PATCH] arm64: kasan: instrument user memory access API

[Yang Shi]

The upstream commit 1771c6e1a567ea0ba2cccc0a4ffe68a1419fd8ef
("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.

Signed-off-by: Yang Shi <yang.shi at linaro.org>
---
v2:
 Adopted the comment from Andrey and Mark to add kasan_check_read/write into
 __copy_to/from_user.

 arch/arm64/include/asm/uaccess.h | 25 +++++++++++++++++++++----
 arch/arm64/kernel/arm64ksyms.c   |  4 ++--
 arch/arm64/lib/copy_from_user.S  |  4 ++--
 arch/arm64/lib/copy_to_user.S    |  4 ++--
 4 files changed, 27 insertions(+), 10 deletions(-)

diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
index 0685d74..4dc9a8f 100644
--- a/arch/arm64/include/asm/uaccess.h
+++ b/arch/arm64/include/asm/uaccess.h
@@ -23,6 +23,7 @@
  */
 #include <linux/string.h>
 #include <linux/thread_info.h>
+#include <linux/kasan-checks.h>
 
 #include <asm/alternative.h>
 #include <asm/cpufeature.h>
@@ -269,15 +270,29 @@ 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;
@@ -285,8 +300,10 @@ static inline unsigned long __must_check copy_from_user(void *to, const void __u
 
 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;
 }
 
diff --git a/arch/arm64/kernel/arm64ksyms.c b/arch/arm64/kernel/arm64ksyms.c
index 678f30b0..2dc4440 100644
--- a/arch/arm64/kernel/arm64ksyms.c
+++ b/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);
 
diff --git a/arch/arm64/lib/copy_from_user.S b/arch/arm64/lib/copy_from_user.S
index 17e8306..0b90497 100644
--- a/arch/arm64/lib/copy_from_user.S
+++ b/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
diff --git a/arch/arm64/lib/copy_to_user.S b/arch/arm64/lib/copy_to_user.S
index 21faae6..7a7efe2 100644
--- a/arch/arm64/lib/copy_to_user.S
+++ b/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
-- 
2.0.2