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Message-Id: <1406020499-5537-4-git-send-email-takahiro.akashi@linaro.org> Date: Tue, 22 Jul 2014 18:14:59 +0900 From: AKASHI Takahiro <takahiro.akashi@...aro.org> To: wad@...omium.org, catalin.marinas@....com, will.deacon@....com, keescook@...omium.org Cc: dsaxena@...aro.org, linux-arm-kernel@...ts.infradead.org, linaro-kernel@...ts.linaro.org, linux-kernel@...r.kernel.org, AKASHI Takahiro <takahiro.akashi@...aro.org> Subject: [PATCH v5 3/3] arm64: Add seccomp support secure_computing() should always be called first in syscall_trace_enter(). If secure_computing() returns -1, we should stop further handling. Then that system call may eventually fail with a specified return value (errno), be trapped or the process itself be killed depending on loaded rules. In these cases, syscall_trace_enter() also returns -1, that results in skiping a normal syscall handling as well as syscall_trace_exit(). Signed-off-by: AKASHI Takahiro <takahiro.akashi@...aro.org> --- arch/arm64/Kconfig | 14 ++++++++++++++ arch/arm64/include/asm/seccomp.h | 25 +++++++++++++++++++++++++ arch/arm64/include/asm/unistd.h | 3 +++ arch/arm64/kernel/ptrace.c | 5 +++++ 4 files changed, 47 insertions(+) create mode 100644 arch/arm64/include/asm/seccomp.h diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 3a18571..eeac003 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -32,6 +32,7 @@ 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_C_RECORDMCOUNT select HAVE_DEBUG_BUGVERBOSE @@ -259,6 +260,19 @@ 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 diff --git a/arch/arm64/include/asm/seccomp.h b/arch/arm64/include/asm/seccomp.h new file mode 100644 index 0000000..c76fac9 --- /dev/null +++ b/arch/arm64/include/asm/seccomp.h @@ -0,0 +1,25 @@ +/* + * arch/arm64/include/asm/seccomp.h + * + * Copyright (C) 2014 Linaro Limited + * Author: AKASHI Takahiro <takahiro.akashi@...aro.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 */ diff --git a/arch/arm64/include/asm/unistd.h b/arch/arm64/include/asm/unistd.h index c980ab7..729c155 100644 --- a/arch/arm64/include/asm/unistd.h +++ b/arch/arm64/include/asm/unistd.h @@ -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 diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c index 100d7d1..e477f6f 100644 --- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c @@ -28,6 +28,7 @@ #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> @@ -1115,6 +1116,10 @@ asmlinkage int syscall_trace_enter(struct pt_regs *regs) saved_x0 = regs->regs[0]; saved_x8 = regs->regs[8]; + if (secure_computing(regs->syscallno) == -1) + /* seccomp failures shouldn't expose any additional code. */ + return -1; + if (test_thread_flag(TIF_SYSCALL_TRACE)) tracehook_report_syscall(regs, PTRACE_SYSCALL_ENTER); -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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