diff --git a/Documentation/userspace-api/spec_ctrl.rst b/Documentation/userspace-api/spec_ctrl.rst
index c4dbe6f7cdae8c8c76e706d773322af79cc26b78..1129c7550a480cb49ccee926ec79293177d4d1cf 100644
--- a/Documentation/userspace-api/spec_ctrl.rst
+++ b/Documentation/userspace-api/spec_ctrl.rst
@@ -28,18 +28,20 @@ PR_GET_SPECULATION_CTRL returns the state of the speculation misfeature
which is selected with arg2 of prctl(2). The return value uses bits 0-3 with
the following meaning:
-==== ===================== ===================================================
-Bit Define Description
-==== ===================== ===================================================
-0 PR_SPEC_PRCTL Mitigation can be controlled per task by
- PR_SET_SPECULATION_CTRL.
-1 PR_SPEC_ENABLE The speculation feature is enabled, mitigation is
- disabled.
-2 PR_SPEC_DISABLE The speculation feature is disabled, mitigation is
- enabled.
-3 PR_SPEC_FORCE_DISABLE Same as PR_SPEC_DISABLE, but cannot be undone. A
- subsequent prctl(..., PR_SPEC_ENABLE) will fail.
-==== ===================== ===================================================
+==== ====================== ==================================================
+Bit Define Description
+==== ====================== ==================================================
+0 PR_SPEC_PRCTL Mitigation can be controlled per task by
+ PR_SET_SPECULATION_CTRL.
+1 PR_SPEC_ENABLE The speculation feature is enabled, mitigation is
+ disabled.
+2 PR_SPEC_DISABLE The speculation feature is disabled, mitigation is
+ enabled.
+3 PR_SPEC_FORCE_DISABLE Same as PR_SPEC_DISABLE, but cannot be undone. A
+ subsequent prctl(..., PR_SPEC_ENABLE) will fail.
+4 PR_SPEC_DISABLE_NOEXEC Same as PR_SPEC_DISABLE, but the state will be
+ cleared on :manpage:`execve(2)`.
+==== ====================== ==================================================
If all bits are 0 the CPU is not affected by the speculation misfeature.
@@ -92,6 +94,7 @@ Speculation misfeature controls
* prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_STORE_BYPASS, PR_SPEC_ENABLE, 0, 0);
* prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_STORE_BYPASS, PR_SPEC_DISABLE, 0, 0);
* prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_STORE_BYPASS, PR_SPEC_FORCE_DISABLE, 0, 0);
+ * prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_STORE_BYPASS, PR_SPEC_DISABLE_NOEXEC, 0, 0);
- PR_SPEC_INDIR_BRANCH: Indirect Branch Speculation in User Processes
(Mitigate Spectre V2 style attacks against user processes)
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 1de0f417017833ec2580e5c95e16870dbcd1c424..2faeaf46347ada052ceb5e8edbc6fc91d6b32101 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -798,15 +798,25 @@ static int ssb_prctl_set(struct task_struct *task, unsigned long ctrl)
if (task_spec_ssb_force_disable(task))
return -EPERM;
task_clear_spec_ssb_disable(task);
+ task_clear_spec_ssb_noexec(task);
task_update_spec_tif(task);
break;
case PR_SPEC_DISABLE:
task_set_spec_ssb_disable(task);
+ task_clear_spec_ssb_noexec(task);
task_update_spec_tif(task);
break;
case PR_SPEC_FORCE_DISABLE:
task_set_spec_ssb_disable(task);
task_set_spec_ssb_force_disable(task);
+ task_clear_spec_ssb_noexec(task);
+ task_update_spec_tif(task);
+ break;
+ case PR_SPEC_DISABLE_NOEXEC:
+ if (task_spec_ssb_force_disable(task))
+ return -EPERM;
+ task_set_spec_ssb_disable(task);
+ task_set_spec_ssb_noexec(task);
task_update_spec_tif(task);
break;
default:
@@ -885,6 +895,8 @@ static int ssb_prctl_get(struct task_struct *task)
case SPEC_STORE_BYPASS_PRCTL:
if (task_spec_ssb_force_disable(task))
return PR_SPEC_PRCTL | PR_SPEC_FORCE_DISABLE;
+ if (task_spec_ssb_noexec(task))
+ return PR_SPEC_PRCTL | PR_SPEC_DISABLE_NOEXEC;
if (task_spec_ssb_disable(task))
return PR_SPEC_PRCTL | PR_SPEC_DISABLE;
return PR_SPEC_PRCTL | PR_SPEC_ENABLE;
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 90ae0ca51083768df899edd88f6016be224c3316..58ac7be52c7a6df944dca7305492b8ce70ed8d8e 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -255,6 +255,18 @@ void arch_setup_new_exec(void)
/* If cpuid was previously disabled for this task, re-enable it. */
if (test_thread_flag(TIF_NOCPUID))
enable_cpuid();
+
+ /*
+ * Don't inherit TIF_SSBD across exec boundary when
+ * PR_SPEC_DISABLE_NOEXEC is used.
+ */
+ if (test_thread_flag(TIF_SSBD) &&
+ task_spec_ssb_noexec(current)) {
+ clear_thread_flag(TIF_SSBD);
+ task_clear_spec_ssb_disable(current);
+ task_clear_spec_ssb_noexec(current);
+ speculation_ctrl_update(task_thread_info(current)->flags);
+ }
}
static inline void switch_to_bitmap(struct thread_struct *prev,
diff --git a/include/linux/sched.h b/include/linux/sched.h
index d2f90fa9246833f6ba4ca726c59e8ddbff3bc504..fc836dc71bbad8ecd7930f3ee5dd121fbd7d0bfd 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1459,6 +1459,7 @@ static inline bool is_percpu_thread(void)
#define PFA_SPEC_SSB_FORCE_DISABLE 4 /* Speculative Store Bypass force disabled*/
#define PFA_SPEC_IB_DISABLE 5 /* Indirect branch speculation restricted */
#define PFA_SPEC_IB_FORCE_DISABLE 6 /* Indirect branch speculation permanently restricted */
+#define PFA_SPEC_SSB_NOEXEC 7 /* Speculative Store Bypass clear on execve() */
#define TASK_PFA_TEST(name, func) \
static inline bool task_##func(struct task_struct *p) \
@@ -1487,6 +1488,10 @@ TASK_PFA_TEST(SPEC_SSB_DISABLE, spec_ssb_disable)
TASK_PFA_SET(SPEC_SSB_DISABLE, spec_ssb_disable)
TASK_PFA_CLEAR(SPEC_SSB_DISABLE, spec_ssb_disable)
+TASK_PFA_TEST(SPEC_SSB_NOEXEC, spec_ssb_noexec)
+TASK_PFA_SET(SPEC_SSB_NOEXEC, spec_ssb_noexec)
+TASK_PFA_CLEAR(SPEC_SSB_NOEXEC, spec_ssb_noexec)
+
TASK_PFA_TEST(SPEC_SSB_FORCE_DISABLE, spec_ssb_force_disable)
TASK_PFA_SET(SPEC_SSB_FORCE_DISABLE, spec_ssb_force_disable)
diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h
index b4875a93363a98676b32098404fda28d86b4aad9..094bb03b9cc2821e79cfd0e606350e9d3e221a02 100644
--- a/include/uapi/linux/prctl.h
+++ b/include/uapi/linux/prctl.h
@@ -219,6 +219,7 @@ struct prctl_mm_map {
# define PR_SPEC_ENABLE (1UL << 1)
# define PR_SPEC_DISABLE (1UL << 2)
# define PR_SPEC_FORCE_DISABLE (1UL << 3)
+# define PR_SPEC_DISABLE_NOEXEC (1UL << 4)
/* Reset arm64 pointer authentication keys */
#define PR_PAC_RESET_KEYS 54
diff --git a/tools/include/uapi/linux/prctl.h b/tools/include/uapi/linux/prctl.h
index b4875a93363a98676b32098404fda28d86b4aad9..094bb03b9cc2821e79cfd0e606350e9d3e221a02 100644
--- a/tools/include/uapi/linux/prctl.h
+++ b/tools/include/uapi/linux/prctl.h
@@ -219,6 +219,7 @@ struct prctl_mm_map {
# define PR_SPEC_ENABLE (1UL << 1)
# define PR_SPEC_DISABLE (1UL << 2)
# define PR_SPEC_FORCE_DISABLE (1UL << 3)
+# define PR_SPEC_DISABLE_NOEXEC (1UL << 4)
/* Reset arm64 pointer authentication keys */
#define PR_PAC_RESET_KEYS 54