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-rw-r--r--arch/x86/kernel/cpu/bugs.c29
-rw-r--r--include/linux/nospec.h2
-rw-r--r--kernel/seccomp.c15
3 files changed, 22 insertions, 24 deletions
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index d6897caa8f47..b005ef721dc7 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -567,6 +567,24 @@ static int ssb_prctl_set(struct task_struct *task, unsigned long ctrl)
return 0;
}
+int arch_prctl_spec_ctrl_set(struct task_struct *task, unsigned long which,
+ unsigned long ctrl)
+{
+ switch (which) {
+ case PR_SPEC_STORE_BYPASS:
+ return ssb_prctl_set(task, ctrl);
+ default:
+ return -ENODEV;
+ }
+}
+
+#ifdef CONFIG_SECCOMP
+void arch_seccomp_spec_mitigate(struct task_struct *task)
+{
+ ssb_prctl_set(task, PR_SPEC_FORCE_DISABLE);
+}
+#endif
+
static int ssb_prctl_get(struct task_struct *task)
{
switch (ssb_mode) {
@@ -585,17 +603,6 @@ static int ssb_prctl_get(struct task_struct *task)
}
}
-int arch_prctl_spec_ctrl_set(struct task_struct *task, unsigned long which,
- unsigned long ctrl)
-{
- switch (which) {
- case PR_SPEC_STORE_BYPASS:
- return ssb_prctl_set(task, ctrl);
- default:
- return -ENODEV;
- }
-}
-
int arch_prctl_spec_ctrl_get(struct task_struct *task, unsigned long which)
{
switch (which) {
diff --git a/include/linux/nospec.h b/include/linux/nospec.h
index a908c954484d..0c5ef54fd416 100644
--- a/include/linux/nospec.h
+++ b/include/linux/nospec.h
@@ -62,5 +62,7 @@ static inline unsigned long array_index_mask_nospec(unsigned long index,
int arch_prctl_spec_ctrl_get(struct task_struct *task, unsigned long which);
int arch_prctl_spec_ctrl_set(struct task_struct *task, unsigned long which,
unsigned long ctrl);
+/* Speculation control for seccomp enforced mitigation */
+void arch_seccomp_spec_mitigate(struct task_struct *task);
#endif /* _LINUX_NOSPEC_H */
diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index 4bb8a5a5d68a..9a9203b15cde 100644
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -216,18 +216,7 @@ 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_FORCE_DISABLE);
-}
+void __weak arch_seccomp_spec_mitigate(struct task_struct *task) { }
static inline void seccomp_assign_mode(struct task_struct *task,
unsigned long seccomp_mode,
@@ -243,7 +232,7 @@ static inline void seccomp_assign_mode(struct task_struct *task,
smp_mb__before_atomic();
/* Assume default seccomp processes want spec flaw mitigation. */
if ((flags & SECCOMP_FILTER_FLAG_SPEC_ALLOW) == 0)
- spec_mitigate(task, PR_SPEC_STORE_BYPASS);
+ arch_seccomp_spec_mitigate(task);
set_tsk_thread_flag(task, TIF_SECCOMP);
}