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authorKees Cook <keescook@chromium.org>2018-05-01 15:07:31 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-05-22 18:54:03 +0200
commit87895ae1e9b22a04441992921b79b6d32e22142a (patch)
treebd481cd8a4e3b45fbc498da18399b2d803acec35
parentdd88d569eeff59a03b897ba0168547a465091aca (diff)
seccomp: Enable speculation flaw mitigations
commit 5c3070890d06ff82eecb808d02d2ca39169533ef upstream 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: Kees Cook <keescook@chromium.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--kernel/seccomp.c17
1 files changed, 17 insertions, 0 deletions
diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index 5f0dfb2abb8d..55f20aee7ea2 100644
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -19,6 +19,8 @@
#include <linux/compat.h>
#include <linux/coredump.h>
#include <linux/kmemleak.h>
+#include <linux/nospec.h>
+#include <linux/prctl.h>
#include <linux/sched.h>
#include <linux/sched/task_stack.h>
#include <linux/seccomp.h>
@@ -227,6 +229,19 @@ static inline bool seccomp_may_assign_mode(unsigned long seccomp_mode)
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,
unsigned long seccomp_mode)
{
@@ -238,6 +253,8 @@ static inline void seccomp_assign_mode(struct task_struct *task,
* filter) is set.
*/
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);
}