Commit 70c70d97 authored by Nicolas Pitre's avatar Nicolas Pitre
Browse files

ARM: SECCOMP support 



Signed-off-by: default avatarNicolas Pitre <nicolas.pitre@linaro.org>
parent 087aaffc

arch/arm/Kconfig

+14 −0
Original line number Diff line number Diff line
@@ -1463,6 +1463,20 @@ config UACCESS_WITH_MEMCPY 
	  However, if the CPU data cache is using a write-allocate mode,

	  this option is unlikely to provide any performance gain.



config SECCOMP

	bool

	prompt "Enable seccomp to safely compute untrusted bytecode"

	---help---

	  This kernel feature is useful for number crunching applications

	  that may need to compute untrusted bytecode during their

	  execution. By using pipes or other transports made available to

	  the process as file descriptors supporting the read/write

	  syscalls, it's possible to isolate those applications in

	  their own address space using seccomp. Once seccomp is

	  enabled via prctl(PR_SET_SECCOMP), it cannot be disabled

	  and the task is only allowed to execute a few safe syscalls

	  defined by each seccomp mode.



config CC_STACKPROTECTOR

	bool "Enable -fstack-protector buffer overflow detection (EXPERIMENTAL)"

	help

arch/arm/include/asm/seccomp.h

0 → 100644
+11 −0
Original line number Diff line number Diff line 
#ifndef _ASM_ARM_SECCOMP_H

#define _ASM_ARM_SECCOMP_H



#include <linux/unistd.h>



#define __NR_seccomp_read __NR_read

#define __NR_seccomp_write __NR_write

#define __NR_seccomp_exit __NR_exit

#define __NR_seccomp_sigreturn __NR_rt_sigreturn



#endif /* _ASM_ARM_SECCOMP_H */

arch/arm/include/asm/thread_info.h

+2 −0
Original line number Diff line number Diff line
@@ -144,6 +144,7 @@ extern void vfp_flush_hwstate(struct thread_info *); 
#define TIF_MEMDIE		18	/* is terminating due to OOM killer */

#define TIF_FREEZE		19

#define TIF_RESTORE_SIGMASK	20

#define TIF_SECCOMP		21



#define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)

#define _TIF_NEED_RESCHED	(1 << TIF_NEED_RESCHED)
@@ -153,6 +154,7 @@ extern void vfp_flush_hwstate(struct thread_info *); 
#define _TIF_USING_IWMMXT	(1 << TIF_USING_IWMMXT)

#define _TIF_FREEZE		(1 << TIF_FREEZE)

#define _TIF_RESTORE_SIGMASK	(1 << TIF_RESTORE_SIGMASK)

#define _TIF_SECCOMP		(1 << TIF_SECCOMP)



/*

 * Change these and you break ASM code in entry-common.S

arch/arm/kernel/entry-common.S

+13 −2
Original line number Diff line number Diff line
@@ -295,7 +295,6 @@ ENTRY(vector_swi) 


	get_thread_info tsk

	adr	tbl, sys_call_table		@ load syscall table pointer

	ldr	ip, [tsk, #TI_FLAGS]		@ check for syscall tracing



#if defined(CONFIG_OABI_COMPAT)

	/*
@@ -312,8 +311,20 @@ ENTRY(vector_swi) 
	eor	scno, scno, #__NR_SYSCALL_BASE	@ check OS number

#endif



	ldr	r10, [tsk, #TI_FLAGS]		@ check for syscall tracing

	stmdb	sp!, {r4, r5}			@ push fifth and sixth args

	tst	ip, #_TIF_SYSCALL_TRACE		@ are we tracing syscalls?



#ifdef CONFIG_SECCOMP

	tst	r10, #_TIF_SECCOMP

	beq	1f

	mov	r0, scno

	bl	__secure_computing	

	add	r0, sp, #S_R0 + S_OFF		@ pointer to regs

	ldmia	r0, {r0 - r3}			@ have to reload r0 - r3

1:

#endif



	tst	r10, #_TIF_SYSCALL_TRACE		@ are we tracing syscalls?

	bne	__sys_trace



	cmp	scno, #NR_syscalls		@ check upper syscall limit