Re: [PATCH 7/7] pid: get pid_t ppid of task in init_pid_ns
On 14/02/20, Oleg Nesterov wrote:
On 01/23, Richard Guy Briggs wrote:
>
> Added the functions task_ppid_nr_ns() and task_ppid_nr() to abstract the lookup
> of the PPID (real_parent's pid_t) of a process, including rcu locking, in the
> arbitrary and init_pid_ns.
> This provides an alternative to sys_getppid(), which is relative to the child
> process' pid namespace.
I agree, this makes sense.
imho it would be better to send this patch along with sys_getppid()
conversions, but I won't argue.
I don't think sys_getppid() should be changed since it is a syscall
whose userspace user would assume the working namespace. Many of the
kernel internal uses of it are likely wrong though, so fixing that
should probably fall under another patch. I fixed audit in another
patch.
> +static int pid_alive(const struct task_struct *p);
> +static inline pid_t task_ppid_nr_ns(const struct task_struct *tsk, struct
pid_namespace *ns)
> +{
> + pid_t pid = 0;
> +
> + rcu_read_lock();
> + if (pid_alive(tsk))
> + pid = task_tgid_nr_ns(rcu_dereference(tsk->real_parent), ns);
> + rcu_read_unlock();
> +
> + return pid;
> +}
Perhaps it should be named task_ptgid_nr_ns() or even parent_tgid_nr_ns().
Since it returns tgid, not pid (== tid).
I like task_ptgid_nr_ns() (or maybe even task_parent_tgid_nr_ns() but
that gets a bit long.
But this is cosmetic, I won't insist.
Oleg.
- RGB
--
Richard Guy Briggs <rbriggs(a)redhat.com>
Senior Software Engineer, Kernel Security, AMER ENG Base Operating Systems, Red Hat
Remote, Ottawa, Canada
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