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Date:   Wed, 7 Aug 2019 18:08:56 +0200
From:   Oleg Nesterov <oleg@redhat.com>
To:     Adrian Reber <areber@redhat.com>
Cc:     Christian Brauner <christian@brauner.io>,
        Eric Biederman <ebiederm@xmission.com>,
        Pavel Emelianov <xemul@virtuozzo.com>,
        Jann Horn <jannh@google.com>,
        Dmitry Safonov <0x7f454c46@gmail.com>,
        linux-kernel@vger.kernel.org, Andrei Vagin <avagin@gmail.com>,
        Mike Rapoport <rppt@linux.ibm.com>,
        Radostin Stoyanov <rstoyanov1@gmail.com>
Subject: Re: [PATCH v3 1/2] fork: extend clone3() to support CLONE_SET_TID
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On 08/06, Adrian Reber wrote:
>
> @@ -2573,6 +2575,14 @@ noinline static int copy_clone_args_from_user(struct kernel_clone_args *kargs,
>  		.tls		= args.tls,
>  	};
>  
> +	if (size == sizeof(struct clone_args)) {
> +		/* Only check permissions if set_tid is actually set. */
> +		if (args.set_tid &&
> +			!ns_capable(pid_ns->user_ns, CAP_SYS_ADMIN))

and I just noticed this uses pid_ns = task_active_pid_ns() ...

is it correct?

I feel I am totally confused, but should we use the same
p->nsproxy->pid_ns_for_children passed to alloc_pid?

Oleg.