Upgrade to 4.4.50-rt62

[kvmfornfv.git] / kernel / kernel / ptrace.c

diff --git a/kernel/kernel/ptrace.c b/kernel/kernel/ptrace.c
index 1004af7..6947f76 100644 (file)
--- a/kernel/kernel/ptrace.c
+++ b/kernel/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);
 
@@ -226,7 +233,7 @@ static int ptrace_has_cap(struct user_namespace *ns, unsigned int mode)
 static int __ptrace_may_access(struct task_struct *task, unsigned int mode)
 {
        const struct cred *cred = current_cred(), *tcred;
-       int dumpable = 0;
+       struct mm_struct *mm;
        kuid_t caller_uid;
        kgid_t caller_gid;
 
@@ -277,16 +284,11 @@ static int __ptrace_may_access(struct task_struct *task, unsigned int mode)
        return -EPERM;
 ok:
        rcu_read_unlock();
-       smp_rmb();
-       if (task->mm)
-               dumpable = get_dumpable(task->mm);
-       rcu_read_lock();
-       if (dumpable != SUID_DUMP_USER &&
-           !ptrace_has_cap(__task_cred(task)->user_ns, mode)) {
-               rcu_read_unlock();
-               return -EPERM;
-       }
-       rcu_read_unlock();
+       mm = task->mm;
+       if (mm &&
+           ((get_dumpable(mm) != SUID_DUMP_USER) &&
+            !ptrace_has_cap(mm->user_ns, mode)))
+           return -EPERM;
 
        return security_ptrace_access_check(task, mode);
 }
@@ -350,10 +352,6 @@ static int ptrace_attach(struct task_struct *task, long request,
 
        if (seize)
                flags |= PT_SEIZED;
-       rcu_read_lock();
-       if (ns_capable(__task_cred(task)->user_ns, CAP_SYS_PTRACE))
-               flags |= PT_PTRACE_CAP;
-       rcu_read_unlock();
        task->ptrace = flags;
 
        __ptrace_link(task, current);