61 lines
1.8 KiB
Diff
61 lines
1.8 KiB
Diff
From foo@baz Mon May 21 21:56:07 CEST 2018
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From: Kees Cook <keescook@chromium.org>
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Date: Tue, 1 May 2018 15:07:31 -0700
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Subject: seccomp: Enable speculation flaw mitigations
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From: Kees Cook <keescook@chromium.org>
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commit 5c3070890d06ff82eecb808d02d2ca39169533ef upstream
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When speculation flaw mitigations are opt-in (via prctl), using seccomp
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will automatically opt-in to these protections, since using seccomp
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indicates at least some level of sandboxing is desired.
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Signed-off-by: Kees Cook <keescook@chromium.org>
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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---
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kernel/seccomp.c | 17 +++++++++++++++++
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1 file changed, 17 insertions(+)
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--- a/kernel/seccomp.c
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+++ b/kernel/seccomp.c
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@@ -19,6 +19,8 @@
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#include <linux/compat.h>
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#include <linux/coredump.h>
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#include <linux/kmemleak.h>
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+#include <linux/nospec.h>
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+#include <linux/prctl.h>
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#include <linux/sched.h>
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#include <linux/sched/task_stack.h>
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#include <linux/seccomp.h>
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@@ -227,6 +229,19 @@ static inline bool seccomp_may_assign_mo
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return true;
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}
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+/*
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+ * If a given speculation mitigation is opt-in (prctl()-controlled),
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+ * select it, by disabling speculation (enabling mitigation).
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+ */
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+static inline void spec_mitigate(struct task_struct *task,
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+ unsigned long which)
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+{
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+ int state = arch_prctl_spec_ctrl_get(task, which);
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+
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+ if (state > 0 && (state & PR_SPEC_PRCTL))
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+ arch_prctl_spec_ctrl_set(task, which, PR_SPEC_DISABLE);
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+}
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+
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static inline void seccomp_assign_mode(struct task_struct *task,
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unsigned long seccomp_mode)
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{
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@@ -238,6 +253,8 @@ static inline void seccomp_assign_mode(s
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* filter) is set.
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*/
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smp_mb__before_atomic();
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+ /* Assume seccomp processes want speculation flaw mitigation. */
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+ spec_mitigate(task, PR_SPEC_STORE_BYPASS);
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set_tsk_thread_flag(task, TIF_SECCOMP);
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}
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