Commit 4fe5cda9 authored by Christophe Leroy's avatar Christophe Leroy Committed by Michael Ellerman
Browse files

powerpc/uaccess: Implement user_read_access_begin and user_write_access_begin 



Add support for selective read or write user access with
user_read_access_begin/end and user_write_access_begin/end.

Signed-off-by: default avatarChristophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/6c83af0f0809ef2a955c39ac622767f6cbede035.1585898438.git.christophe.leroy@c-s.fr
parent 1f59cc34

arch/powerpc/include/asm/book3s/32/kup.h

+2 −2
Original line number Diff line number Diff line
@@ -108,7 +108,7 @@ static __always_inline void allow_user_access(void __user *to, const void __user 
	u32 addr, end;



	BUILD_BUG_ON(!__builtin_constant_p(dir));

	BUILD_BUG_ON(dir == KUAP_CURRENT);

	BUILD_BUG_ON(dir & ~KUAP_READ_WRITE);



	if (!(dir & KUAP_WRITE))

		return;
@@ -131,7 +131,7 @@ static __always_inline void prevent_user_access(void __user *to, const void __us 


	BUILD_BUG_ON(!__builtin_constant_p(dir));



	if (dir == KUAP_CURRENT) {

	if (dir & KUAP_CURRENT_WRITE) {

		u32 kuap = current->thread.kuap;



		if (unlikely(!kuap))

arch/powerpc/include/asm/kup.h

+13 −1
Original line number Diff line number Diff line
@@ -10,7 +10,9 @@ 
 * Use the current saved situation instead of the to/from/size params.

 * Used on book3s/32

 */

#define KUAP_CURRENT	4

#define KUAP_CURRENT_READ	4

#define KUAP_CURRENT_WRITE	8

#define KUAP_CURRENT		(KUAP_CURRENT_READ | KUAP_CURRENT_WRITE)



#ifdef CONFIG_PPC64

#include <asm/book3s/64/kup-radix.h>
@@ -101,6 +103,16 @@ static inline void prevent_current_access_user(void) 
	prevent_user_access(NULL, NULL, ~0UL, KUAP_CURRENT);

}



static inline void prevent_current_read_from_user(void)

{

	prevent_user_access(NULL, NULL, ~0UL, KUAP_CURRENT_READ);

}



static inline void prevent_current_write_to_user(void)

{

	prevent_user_access(NULL, NULL, ~0UL, KUAP_CURRENT_WRITE);

}



#endif /* !__ASSEMBLY__ */



#endif /* _ASM_POWERPC_KUAP_H_ */

arch/powerpc/include/asm/uaccess.h

+22 −0
Original line number Diff line number Diff line
@@ -532,6 +532,28 @@ static __must_check inline bool user_access_begin(const void __user *ptr, size_t 
#define user_access_save	prevent_user_access_return

#define user_access_restore	restore_user_access



static __must_check inline bool

user_read_access_begin(const void __user *ptr, size_t len)

{

	if (unlikely(!access_ok(ptr, len)))

		return false;

	allow_read_from_user(ptr, len);

	return true;

}

#define user_read_access_begin	user_read_access_begin

#define user_read_access_end		prevent_current_read_from_user



static __must_check inline bool

user_write_access_begin(const void __user *ptr, size_t len)

{

	if (unlikely(!access_ok(ptr, len)))

		return false;

	allow_write_to_user((void __user *)ptr, len);

	return true;

}

#define user_write_access_begin	user_write_access_begin

#define user_write_access_end		prevent_current_write_to_user



#define unsafe_op_wrap(op, err) do { if (unlikely(op)) goto err; } while (0)

#define unsafe_get_user(x, p, e) unsafe_op_wrap(__get_user_allowed(x, p), e)

#define unsafe_put_user(x, p, e) __put_user_goto(x, p, e)