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Commit 48dc92b9 authored Jun 25, 2014 by Kees Cook

seccomp: add "seccomp" syscall

This adds the new "seccomp" syscall with both an "operation" and "flags"
parameter for future expansion. The third argument is a pointer value,
used with the SECCOMP_SET_MODE_FILTER operation. Currently, flags must
be 0. This is functionally equivalent to prctl(PR_SET_SECCOMP, ...).

In addition to the TSYNC flag later in this patch series, there is a
non-zero chance that this syscall could be used for configuring a fixed
argument area for seccomp-tracer-aware processes to pass syscall arguments
in the future. Hence, the use of "seccomp" not simply "seccomp_add_filter"
for this syscall. Additionally, this syscall uses operation, flags,
and user pointer for arguments because strictly passing arguments via
a user pointer would mean seccomp itself would be unable to trivially
filter the seccomp syscall itself.

Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Andy Lutomirski <luto@amacapital.net>

parent 3b23dd12

arch/Kconfig

+1 −0

Original line number	Original line	Diff line number	Diff line
	@@ -321,6 +321,7 @@ config HAVE_ARCH_SECCOMP_FILTER
	- secure_computing is called from a ptrace_event()-safe context		- secure_computing is called from a ptrace_event()-safe context
	- secure_computing return value is checked and a return value of -1		- secure_computing return value is checked and a return value of -1
	results in the system call being skipped immediately.		results in the system call being skipped immediately.
			- seccomp syscall wired up

	config SECCOMP_FILTER		config SECCOMP_FILTER
	def_bool y		def_bool y

arch/x86/syscalls/syscall_32.tbl

+1 −0

Original line number	Original line	Diff line number	Diff line
	@@ -360,3 +360,4 @@
	351 i386 sched_setattr sys_sched_setattr		351 i386 sched_setattr sys_sched_setattr
	352 i386 sched_getattr sys_sched_getattr		352 i386 sched_getattr sys_sched_getattr
	353 i386 renameat2 sys_renameat2		353 i386 renameat2 sys_renameat2
			354 i386 seccomp sys_seccomp

arch/x86/syscalls/syscall_64.tbl

+1 −0

Original line number	Original line	Diff line number	Diff line
	@@ -323,6 +323,7 @@
	314 common sched_setattr sys_sched_setattr		314 common sched_setattr sys_sched_setattr
	315 common sched_getattr sys_sched_getattr		315 common sched_getattr sys_sched_getattr
	316 common renameat2 sys_renameat2		316 common renameat2 sys_renameat2
			317 common seccomp sys_seccomp

	#		#
	# x32-specific system call numbers start at 512 to avoid cache impact		# x32-specific system call numbers start at 512 to avoid cache impact

include/linux/syscalls.h

+2 −0

Original line number	Original line	Diff line number	Diff line
	@@ -866,4 +866,6 @@ asmlinkage long sys_process_vm_writev(pid_t pid,
	asmlinkage long sys_kcmp(pid_t pid1, pid_t pid2, int type,		asmlinkage long sys_kcmp(pid_t pid1, pid_t pid2, int type,
	unsigned long idx1, unsigned long idx2);		unsigned long idx1, unsigned long idx2);
	asmlinkage long sys_finit_module(int fd, const char __user *uargs, int flags);		asmlinkage long sys_finit_module(int fd, const char __user *uargs, int flags);
			asmlinkage long sys_seccomp(unsigned int op, unsigned int flags,
			const char __user *uargs);
	#endif		#endif

include/uapi/asm-generic/unistd.h

+3 −1

Original line number	Original line	Diff line number	Diff line
	@@ -699,9 +699,11 @@ __SYSCALL(__NR_sched_setattr, sys_sched_setattr)
	__SYSCALL(__NR_sched_getattr, sys_sched_getattr)		__SYSCALL(__NR_sched_getattr, sys_sched_getattr)
	#define __NR_renameat2 276		#define __NR_renameat2 276
	__SYSCALL(__NR_renameat2, sys_renameat2)		__SYSCALL(__NR_renameat2, sys_renameat2)
			#define __NR_seccomp 277
			__SYSCALL(__NR_seccomp, sys_seccomp)

	#undef __NR_syscalls		#undef __NR_syscalls
	#define __NR_syscalls 277		#define __NR_syscalls 278

	/*		/*
	* All syscalls below here should go away really,		* All syscalls below here should go away really,