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Commit 5c307089 authored by Kees Cook's avatar Kees Cook Committed by Thomas Gleixner
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seccomp: Enable speculation flaw mitigations 



When speculation flaw mitigations are opt-in (via prctl), using seccomp
will automatically opt-in to these protections, since using seccomp
indicates at least some level of sandboxing is desired.

Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent fae1fa0f

kernel/seccomp.c

+17 −0
Original line number Original line Diff line number Diff line
@@ -19,6 +19,8 @@ 
#include <linux/compat.h>

#include <linux/compat.h>

#include <linux/coredump.h>

#include <linux/coredump.h>

#include <linux/kmemleak.h>

#include <linux/kmemleak.h>

#include <linux/nospec.h>

#include <linux/prctl.h>

#include <linux/sched.h>

#include <linux/sched.h>

#include <linux/sched/task_stack.h>

#include <linux/sched/task_stack.h>

#include <linux/seccomp.h>

#include <linux/seccomp.h>
@@ -227,6 +229,19 @@ static inline bool seccomp_may_assign_mode(unsigned long seccomp_mode) 
	return true;

	return true;

}

}





/*

 * If a given speculation mitigation is opt-in (prctl()-controlled),

 * select it, by disabling speculation (enabling mitigation).

 */

static inline void spec_mitigate(struct task_struct *task,

				 unsigned long which)

{

	int state = arch_prctl_spec_ctrl_get(task, which);



	if (state > 0 && (state & PR_SPEC_PRCTL))

		arch_prctl_spec_ctrl_set(task, which, PR_SPEC_DISABLE);

}



static inline void seccomp_assign_mode(struct task_struct *task,

static inline void seccomp_assign_mode(struct task_struct *task,

				       unsigned long seccomp_mode)

				       unsigned long seccomp_mode)

{

{
@@ -238,6 +253,8 @@ static inline void seccomp_assign_mode(struct task_struct *task, 
	 * filter) is set.

	 * filter) is set.

	 */

	 */

	smp_mb__before_atomic();

	smp_mb__before_atomic();

	/* Assume seccomp processes want speculation flaw mitigation. */

	spec_mitigate(task, PR_SPEC_STORE_BYPASS);

	set_tsk_thread_flag(task, TIF_SECCOMP);

	set_tsk_thread_flag(task, TIF_SECCOMP);

}

}