capabilities: remove task_ns_* functions

task_ in the front of a function, in the security subsystem anyway, means
to me at least, that we are operating with that task as the subject of the
security decision.  In this case what it means is that we are using current as
the subject but we use the task to get the right namespace.  Who in the world
would ever realize that's what task_ns_capability means just by the name?  This
patch eliminates the task_ns functions entirely and uses the has_ns_capability
function instead.  This means we explicitly open code the ns in question in
the caller.  I think it makes the caller a LOT more clear what is going on.

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Serge E. Hallyn <serge.hallyn@canonical.com>

3 files changed, 3 insertions, 17 deletions

diff --git a/kernel/capability.c b/kernel/capability.c
index 47626446c39a..74fb3b603045 100644
--- a/kernel/capability.c
+++ b/kernel/capability.c
@@ -409,20 +409,6 @@ bool capable(int cap)
 EXPORT_SYMBOL(capable);
 
 /**
- * task_ns_capable - Determine whether current task has a superior
- * capability targeted at a specific task's user namespace.
- * @t: The task whose user namespace is targeted.
- * @cap: The capability in question.
- *
- *  Return true if it does, false otherwise.
- */
-bool task_ns_capable(struct task_struct *t, int cap)
-{
-	return ns_capable(task_cred_xxx(t, user)->user_ns, cap);
-}
-EXPORT_SYMBOL(task_ns_capable);
-
-/**
  * nsown_capable - Check superior capability to one's own user_ns
  * @cap: The capability in question
  *
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index a70d2a5d8c7b..210bbf045ee9 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -196,7 +196,7 @@ ok:
 	smp_rmb();
 	if (task->mm)
 		dumpable = get_dumpable(task->mm);
-	if (!dumpable && !task_ns_capable(task, CAP_SYS_PTRACE))
+	if (!dumpable && !ns_capable(task_user_ns(task), CAP_SYS_PTRACE))
 		return -EPERM;
 
 	return security_ptrace_access_check(task, mode);
@@ -266,7 +266,7 @@ static int ptrace_attach(struct task_struct *task, long request,
 	task->ptrace = PT_PTRACED;
 	if (seize)
 		task->ptrace |= PT_SEIZED;
-	if (task_ns_capable(task, CAP_SYS_PTRACE))
+	if (ns_capable(task_user_ns(task), CAP_SYS_PTRACE))
 		task->ptrace |= PT_PTRACE_CAP;
 
 	__ptrace_link(task, current);
diff --git a/kernel/sched.c b/kernel/sched.c
index b50b0f0c9aa9..5670028a9c16 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -5409,7 +5409,7 @@ long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
 		goto out_free_cpus_allowed;
 	}
 	retval = -EPERM;
-	if (!check_same_owner(p) && !task_ns_capable(p, CAP_SYS_NICE))
+	if (!check_same_owner(p) && !ns_capable(task_user_ns(p), CAP_SYS_NICE))
 		goto out_unlock;
 
 	retval = security_task_setscheduler(p);