linux-kernel - Re: [PATCH] Yama: turn process ancestry check into function

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <201007140019.o6E0J9gQ060582@www262.sakura.ne.jp>
Date:	Wed, 14 Jul 2010 09:19:09 +0900
From:	Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
To:	kees.cook@...onical.com
Cc:	linux-kernel@...r.kernel.org, linux-security-module@...r.kernel.org
Subject: Re: [PATCH] Yama: turn process ancestry check into function

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.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/