nospec: Allow getting/setting on non-current task

Adjust arch_prctl_get/set_spec_ctrl() to operate on tasks other than
current.

This is needed both for /proc/$pid/status queries and for seccomp (since
thread-syncing can trigger seccomp in non-current threads).

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 5 insertions, 4 deletions

diff --git a/kernel/sys.c b/kernel/sys.c
index b76dee23bdc9..b0eee418ee0d 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -2244,12 +2244,13 @@ static int propagate_has_child_subreaper(struct task_struct *p, void *data)
         return 1;
 }
 
-int __weak arch_prctl_spec_ctrl_get(unsigned long which)
+int __weak arch_prctl_spec_ctrl_get(struct task_struct *t, unsigned long which)
 {
         return -EINVAL;
 }
 
-int __weak arch_prctl_spec_ctrl_set(unsigned long which, unsigned long ctrl)
+int __weak arch_prctl_spec_ctrl_set(struct task_struct *t, unsigned long which,
+                                    unsigned long ctrl)
 {
         return -EINVAL;
 }
@@ -2465,12 +2466,12 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
         case PR_GET_SPECULATION_CTRL:
                 if (arg3 || arg4 || arg5)
                         return -EINVAL;
-                error = arch_prctl_spec_ctrl_get(arg2);
+                error = arch_prctl_spec_ctrl_get(me, arg2);
                 break;
         case PR_SET_SPECULATION_CTRL:
                 if (arg4 || arg5)
                         return -EINVAL;
-                error = arch_prctl_spec_ctrl_set(arg2, arg3);
+                error = arch_prctl_spec_ctrl_set(me, arg2, arg3);
                 break;
         default:
                 error = -EINVAL;