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Commit faf5b63e authored by Kees Cook's avatar Kees Cook
Browse files

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: default avatarKees Cook <keescook@chromium.org>
parent dfd45b61

arch/arm64/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -51,6 +51,7 @@ config ARM64 
	select HAVE_ALIGNED_STRUCT_PAGE if SLUB

	select HAVE_ARCH_AUDITSYSCALL

	select HAVE_ARCH_BITREVERSE

	select HAVE_ARCH_HARDENED_USERCOPY

	select HAVE_ARCH_HUGE_VMAP

	select HAVE_ARCH_JUMP_LABEL

	select HAVE_ARCH_KASAN if SPARSEMEM_VMEMMAP && !(ARM64_16K_PAGES && ARM64_VA_BITS_48)

arch/arm64/include/asm/uaccess.h

+22 −7
Original line number Diff line number Diff line
@@ -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;

}

arch/arm64/kernel/arm64ksyms.c

+2 −2
Original line number Diff line number Diff line
@@ -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

+2 −2
Original line number Diff line number Diff line
@@ -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

+2 −2
Original line number Diff line number Diff line
@@ -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