proc: Provide details on speculation flaw mitigations

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

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
CVE-2018-3639 (x86)

Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/fs/proc/array.c b/fs/proc/array.c
index 525157ca25cbe6a706ecb05c631b2b6d0bcb59a9..928b2b7fb8220b7c9dceb41e519fdec0fc3d0dba 100644 (file)
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -84,6 +84,8 @@
 #include <linux/delayacct.h>
 #include <linux/seq_file.h>
 #include <linux/pid_namespace.h>
+#include <linux/nospec.h>
+#include <linux/prctl.h>
 #include <linux/ptrace.h>
 #include <linux/tracehook.h>
 #include <linux/string_helpers.h>
@@ -351,6 +353,27 @@ static inline void task_seccomp(struct seq_file *m, struct task_struct *p)
 #ifdef CONFIG_SECCOMP
        seq_put_decimal_ull(m, "\nSeccomp:\t", p->seccomp.mode);
 #endif
+       seq_printf(m, "\nSpeculation 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');
 }