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Commit 08626a60 authored by Kees Cook's avatar Kees Cook
Browse files

arm: Implement thread_struct whitelist for hardened usercopy 



While ARM32 carries FPU state in the thread structure that is saved and
restored during signal handling, it doesn't need to declare a usercopy
whitelist, since existing accessors are all either using a bounce buffer
(for which whitelisting isn't checking the slab), are statically sized
(which will bypass the hardened usercopy check), or both.

Cc: Russell King <linux@armlinux.org.uk>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
parent 9e8084d3

arch/arm/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -50,6 +50,7 @@ config ARM 
	select HAVE_ARCH_KGDB if !CPU_ENDIAN_BE32 && MMU

	select HAVE_ARCH_MMAP_RND_BITS if MMU

	select HAVE_ARCH_SECCOMP_FILTER if (AEABI && !OABI_COMPAT)

	select HAVE_ARCH_THREAD_STRUCT_WHITELIST

	select HAVE_ARCH_TRACEHOOK

	select HAVE_ARM_SMCCC if CPU_V7

	select HAVE_EBPF_JIT if !CPU_ENDIAN_BE32

arch/arm/include/asm/processor.h

+10 −0
Original line number Diff line number Diff line
@@ -45,6 +45,16 @@ struct thread_struct { 
	struct debug_info	debug;

};



/*

 * Everything usercopied to/from thread_struct is statically-sized, so

 * no hardened usercopy whitelist is needed.

 */

static inline void arch_thread_struct_whitelist(unsigned long *offset,

						unsigned long *size)

{

	*offset = *size = 0;

}



#define INIT_THREAD  {	}



#define start_thread(regs,pc,sp)					\