arm64: Add support for PR_SPEC_DISABLE_NOEXEC prctl() option
The PR_SPEC_DISABLE_NOEXEC option to the PR_SPEC_STORE_BYPASS prctl()
allows the SSB mitigation to be enabled only until the next execve(),
at which point the state will revert back to PR_SPEC_ENABLE and the
mitigation will be disabled.
Add support for PR_SPEC_DISABLE_NOEXEC on arm64.
Reported-by: Anthony Steinhauser <asteinhauser@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 9dbd35b..085d8ca 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -21,6 +21,7 @@
#include <linux/lockdep.h>
#include <linux/mman.h>
#include <linux/mm.h>
+#include <linux/nospec.h>
#include <linux/stddef.h>
#include <linux/sysctl.h>
#include <linux/unistd.h>
@@ -609,6 +610,11 @@ void arch_setup_new_exec(void)
current->mm->context.flags = is_compat_task() ? MMCF_AARCH32 : 0;
ptrauth_thread_init_user(current);
+
+ if (task_spec_ssb_noexec(current)) {
+ arch_prctl_spec_ctrl_set(current, PR_SPEC_STORE_BYPASS,
+ PR_SPEC_ENABLE);
+ }
}
#ifdef CONFIG_ARM64_TAGGED_ADDR_ABI
