[PATCH 3.16 018/131] proc: Provide details on speculation flaw mitigations

From: Ben Hutchings
Date: Sat Sep 29 2018 - 18:02:06 EST


3.16.59-rc1 review patch. If anyone has any objections, please let me know.

------------------

From: Kees Cook <keescook@xxxxxxxxxxxx>

commit fae1fa0fc6cca8beee3ab8ed71d54f9a78fa3f64 upstream.

As done with seccomp and no_new_privs, also show speculation flaw
mitigation state in /proc/$pid/status.

Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
fs/proc/array.c | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)

--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -79,6 +79,7 @@
#include <linux/delayacct.h>
#include <linux/seq_file.h>
#include <linux/pid_namespace.h>
+#include <linux/prctl.h>
#include <linux/ptrace.h>
#include <linux/tracehook.h>
#include <linux/user_namespace.h>
@@ -326,6 +327,28 @@ static inline void task_seccomp(struct s
#ifdef CONFIG_SECCOMP
seq_printf(m, "Seccomp:\t%d\n", p->seccomp.mode);
#endif
+ seq_printf(m, "Speculation Store Bypass:\t");
+ switch (arch_prctl_spec_ctrl_get(p, PR_SPEC_STORE_BYPASS)) {
+ case -EINVAL:
+ seq_printf(m, "unknown");
+ break;
+ case PR_SPEC_NOT_AFFECTED:
+ seq_printf(m, "not vulnerable");
+ break;
+ case PR_SPEC_PRCTL | PR_SPEC_DISABLE:
+ seq_printf(m, "thread mitigated");
+ break;
+ case PR_SPEC_PRCTL | PR_SPEC_ENABLE:
+ seq_printf(m, "thread vulnerable");
+ break;
+ case PR_SPEC_DISABLE:
+ seq_printf(m, "globally mitigated");
+ break;
+ default:
+ seq_printf(m, "vulnerable");
+ break;
+ }
+ seq_putc(m, '\n');
}

static inline void task_context_switch_counts(struct seq_file *m,