From: Kees Cook <keescook@chromium.org>
Date: Thu, 23 Jun 2016 22:10:01 +0000 (-0700)
Subject: powerpc/uaccess: Enable hardened usercopy
X-Git-Tag: firefly_0821_release~176^2~4^2~33^2~4
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=225237bf68dc39bc952781d2b54732d70187fd28;p=firefly-linux-kernel-4.4.55.git

powerpc/uaccess: Enable hardened usercopy

Enables CONFIG_HARDENED_USERCOPY checks on powerpc.

Based on code from PaX and grsecurity.

Signed-off-by: Kees Cook <keescook@chromium.org>
Tested-by: Michael Ellerman <mpe@ellerman.id.au>
(cherry picked from commit 1d3c1324746fed0e34a5b94d3ed303e7521ed603)
Signed-off-by: Alex Shi <alex.shi@linaro.org>
---

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index db49e0d796b1..ec7b8f1e4822 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -160,6 +160,7 @@ config PPC
 	select EDAC_ATOMIC_SCRUB
 	select ARCH_HAS_DMA_SET_COHERENT_MASK
 	select HAVE_ARCH_SECCOMP_FILTER
+	select HAVE_ARCH_HARDENED_USERCOPY
 
 config GENERIC_CSUM
 	def_bool CPU_LITTLE_ENDIAN
diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h
index 2a8ebae0936b..b39a69370057 100644
--- a/arch/powerpc/include/asm/uaccess.h
+++ b/arch/powerpc/include/asm/uaccess.h
@@ -325,10 +325,15 @@ static inline unsigned long copy_from_user(void *to,
 {
 	unsigned long over;
 
-	if (access_ok(VERIFY_READ, from, n))
+	if (access_ok(VERIFY_READ, from, n)) {
+		if (!__builtin_constant_p(n))
+			check_object_size(to, n, false);
 		return __copy_tofrom_user((__force void __user *)to, from, n);
+	}
 	if ((unsigned long)from < TASK_SIZE) {
 		over = (unsigned long)from + n - TASK_SIZE;
+		if (!__builtin_constant_p(n - over))
+			check_object_size(to, n - over, false);
 		return __copy_tofrom_user((__force void __user *)to, from,
 				n - over) + over;
 	}
@@ -340,10 +345,15 @@ static inline unsigned long copy_to_user(void __user *to,
 {
 	unsigned long over;
 
-	if (access_ok(VERIFY_WRITE, to, n))
+	if (access_ok(VERIFY_WRITE, to, n)) {
+		if (!__builtin_constant_p(n))
+			check_object_size(from, n, true);
 		return __copy_tofrom_user(to, (__force void __user *)from, n);
+	}
 	if ((unsigned long)to < TASK_SIZE) {
 		over = (unsigned long)to + n - TASK_SIZE;
+		if (!__builtin_constant_p(n))
+			check_object_size(from, n - over, true);
 		return __copy_tofrom_user(to, (__force void __user *)from,
 				n - over) + over;
 	}
@@ -387,6 +397,10 @@ static inline unsigned long __copy_from_user_inatomic(void *to,
 		if (ret == 0)
 			return 0;
 	}
+
+	if (!__builtin_constant_p(n))
+		check_object_size(to, n, false);
+
 	return __copy_tofrom_user((__force void __user *)to, from, n);
 }
 
@@ -413,6 +427,9 @@ static inline unsigned long __copy_to_user_inatomic(void __user *to,
 		if (ret == 0)
 			return 0;
 	}
+	if (!__builtin_constant_p(n))
+		check_object_size(from, n, true);
+
 	return __copy_tofrom_user(to, (__force const void __user *)from, n);
 }