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arm64: add seccomp support

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secure_computing() is called first in syscall_trace_enter() so that
a system call will be aborted quickly without doing succeeding syscall
tracing if seccomp rules want to deny that system call.

On compat task, syscall numbers for system calls allowed in seccomp mode 1
are different from those on normal tasks, and so _NR_seccomp_xxx_32's need
to be redefined.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
AKASHI Takahiro 2014-11-28 05:26:39 +00:00 committed by Will Deacon
parent cc5e9097c9
commit a1ae65b219
4 changed files with 47 additions and 0 deletions
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14
arch/arm64/Kconfig
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@ -38,6 +38,7 @@ config ARM64
select HAVE_ARCH_AUDITSYSCALL
select HAVE_ARCH_JUMP_LABEL
select HAVE_ARCH_KGDB
select HAVE_ARCH_SECCOMP_FILTER
select HAVE_ARCH_TRACEHOOK
select HAVE_BPF_JIT
select HAVE_C_RECORDMCOUNT
@ -455,6 +456,19 @@ config ARCH_HAS_CACHE_LINE_SIZE
source "mm/Kconfig"
config SECCOMP
bool "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 XEN_DOM0
def_bool y
depends on XEN

25
arch/arm64/include/asm/seccomp.h Normal file
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@ -0,0 +1,25 @@
/*
* arch/arm64/include/asm/seccomp.h
*
* Copyright (C) 2014 Linaro Limited
* Author: AKASHI Takahiro <takahiro.akashi@linaro.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#ifndef _ASM_SECCOMP_H
#define _ASM_SECCOMP_H
#include <asm/unistd.h>
#ifdef CONFIG_COMPAT
#define __NR_seccomp_read_32 __NR_compat_read
#define __NR_seccomp_write_32 __NR_compat_write
#define __NR_seccomp_exit_32 __NR_compat_exit
#define __NR_seccomp_sigreturn_32 __NR_compat_rt_sigreturn
#endif /* CONFIG_COMPAT */
#include <asm-generic/seccomp.h>
#endif /* _ASM_SECCOMP_H */

3
arch/arm64/include/asm/unistd.h
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@ -31,6 +31,9 @@
* Compat syscall numbers used by the AArch64 kernel.
*/
#define __NR_compat_restart_syscall 0
#define __NR_compat_exit 1
#define __NR_compat_read 3
#define __NR_compat_write 4
#define __NR_compat_sigreturn 119
#define __NR_compat_rt_sigreturn 173

5
arch/arm64/kernel/ptrace.c
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@ -27,6 +27,7 @@
#include <linux/smp.h>
#include <linux/ptrace.h>
#include <linux/user.h>
#include <linux/seccomp.h>
#include <linux/security.h>
#include <linux/init.h>
#include <linux/signal.h>
@ -1149,6 +1150,10 @@ static void tracehook_report_syscall(struct pt_regs *regs,
asmlinkage int syscall_trace_enter(struct pt_regs *regs)
{
/* Do the secure computing check first; failures should be fast. */
if (secure_computing() == -1)
return -1;
if (test_thread_flag(TIF_SYSCALL_TRACE))
tracehook_report_syscall(regs, PTRACE_SYSCALL_ENTER);