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From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
To: kees.cook@canonical.com
Cc: linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org
Subject: Re: [PATCH] Yama: turn process ancestry check into function
Date: Wed, 14 Jul 2010 09:19:09 +0900	[thread overview]
Message-ID: <201007140019.o6E0J9gQ060582@www262.sakura.ne.jp> (raw)
In-Reply-To: <20100713173339.GA6104@outflux.net>

Kees Cook wrote:
> +static int task_is_descendant(struct task_struct *parent,
> +			      struct task_struct *child)
> +{
> +	int rc = 0;
> +	struct task_struct *walker = child;
> +
> +	if (!parent || !child)
> +		return 0;

parent (== current) is !NULL and
child (in original code) is !NULL.
You can remove this check unless you are planning to call
this function from other places.

> +	if (mode == PTRACE_MODE_ATTACH &&
> +	    ptrace_scope &&
> +	    !task_is_descendant(current, child) &&
> +	    !capable(CAP_SYS_PTRACE))
> +		rc = -EPERM;

I don't know how heavy capable(CAP_SYS_PTRACE) is.
But checking !capable(CAP_SYS_PTRACE) before
!task_is_descendant(current, child) might be lighter.

  reply	other threads:[~2010-07-14  0:19 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-07-13 17:33 [PATCH] Yama: turn process ancestry check into function Kees Cook
2010-07-14  0:19 ` Tetsuo Handa [this message]
2010-07-14  0:30   ` Kees Cook
2010-07-14  2:17     ` Serge E. Hallyn
2010-07-20 23:02 ` James Morris

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