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Subject[Patch v3 12/13] x86/speculation: Protect non-dumpable processes against Spectre v2 attack
Date
Mark the non-dumpable processes with TIF_STIBP flag so they will
use STIBP and IBPB defenses against Spectre v2 attack from
processes in user space.

Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
---
arch/x86/kernel/cpu/bugs.c | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 1d317f2..cc77b9e 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -14,6 +14,7 @@
#include <linux/module.h>
#include <linux/nospec.h>
#include <linux/prctl.h>
+#include <linux/sched/coredump.h>

#include <asm/spec-ctrl.h>
#include <asm/cmdline.h>
@@ -773,6 +774,26 @@ int arch_prctl_spec_ctrl_set(struct task_struct *task, unsigned long which,
}
}

+void arch_set_dumpable(struct task_struct *tsk, unsigned int value)
+{
+ bool update;
+
+ if (!static_branch_unlikely(&spectre_v2_app_lite))
+ return;
+ if (!static_cpu_has(X86_FEATURE_STIBP))
+ return;
+ if (spectre_v2_app2app_enabled == SPECTRE_V2_APP2APP_NONE)
+ return;
+
+ if (tsk->mm && value != SUID_DUMP_USER)
+ update = !test_and_set_tsk_thread_flag(tsk, TIF_STIBP);
+ else
+ update = test_and_clear_tsk_thread_flag(tsk, TIF_STIBP);
+
+ if (tsk == current && update)
+ speculation_ctrl_update_current();
+}
+
#ifdef CONFIG_SECCOMP
void arch_seccomp_spec_mitigate(struct task_struct *task)
{
--
2.9.4
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