ptrace: Capture the ptracer's creds not PT_PTRACE_CAP

[firefly-linux-kernel-4.4.55.git] / kernel / ptrace.c

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 21b60e0a30560a26c47a169582cebbc48bb5bd7f..a46c40bfb5f669f04f6b42c8c06ea0c61ba63360 100644 (file)
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -39,6 +39,9 @@ void __ptrace_link(struct task_struct *child, struct task_struct *new_parent)
        BUG_ON(!list_empty(&child->ptrace_entry));
        list_add(&child->ptrace_entry, &new_parent->ptraced);
        child->parent = new_parent;
+       rcu_read_lock();
+       child->ptracer_cred = get_cred(__task_cred(new_parent));
+       rcu_read_unlock();
 }
 
 /**
@@ -71,11 +74,15 @@ void __ptrace_link(struct task_struct *child, struct task_struct *new_parent)
  */
 void __ptrace_unlink(struct task_struct *child)
 {
+       const struct cred *old_cred;
        BUG_ON(!child->ptrace);
 
        child->ptrace = 0;
        child->parent = child->real_parent;
        list_del_init(&child->ptrace_entry);
+       old_cred = child->ptracer_cred;
+       child->ptracer_cred = NULL;
+       put_cred(old_cred);
 
        spin_lock(&child->sighand->siglock);
 
@@ -325,11 +332,6 @@ static int ptrace_attach(struct task_struct *task, long request,
 
        task_lock(task);
        retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH_REALCREDS);
-       if (!retval) {
-               struct mm_struct *mm = task->mm;
-               if (mm && ns_capable(mm->user_ns, CAP_SYS_PTRACE))
-                       flags |= PT_PTRACE_CAP;
-       }
        task_unlock(task);
        if (retval)
                goto unlock_creds;