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Date:   Fri, 19 Mar 2021 11:45:38 -0700
From:   Kees Cook <keescook@chromium.org>
To:     =?iso-8859-1?Q?Micka=EBl_Sala=FCn?= <mic@digikod.net>
Cc:     James Morris <jmorris@namei.org>, Jann Horn <jannh@google.com>,
        "Serge E . Hallyn" <serge@hallyn.com>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Andrew Morton <akpm@linux-foundation.org>,
        Andy Lutomirski <luto@amacapital.net>,
        Anton Ivanov <anton.ivanov@cambridgegreys.com>,
        Arnd Bergmann <arnd@arndb.de>,
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        Jeff Dike <jdike@addtoit.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Michael Kerrisk <mtk.manpages@gmail.com>,
        Richard Weinberger <richard@nod.at>,
        Shuah Khan <shuah@kernel.org>,
        Vincent Dagonneau <vincent.dagonneau@ssi.gouv.fr>,
        kernel-hardening@lists.openwall.com, linux-api@vger.kernel.org,
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        linux-kselftest@vger.kernel.org,
        linux-security-module@vger.kernel.org, x86@kernel.org,
        =?iso-8859-1?Q?Micka=EBl_Sala=FCn?= <mic@linux.microsoft.com>
Subject: Re: [PATCH v30 04/12] landlock: Add ptrace restrictions
Message-ID: <202103191145.C8BA4DC@keescook>
References: <20210316204252.427806-1-mic@digikod.net>
 <20210316204252.427806-5-mic@digikod.net>
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On Tue, Mar 16, 2021 at 09:42:44PM +0100, Micka?l Sala?n wrote:
> From: Micka?l Sala?n <mic@linux.microsoft.com>
> 
> Using ptrace(2) and related debug features on a target process can lead
> to a privilege escalation.  Indeed, ptrace(2) can be used by an attacker
> to impersonate another task and to remain undetected while performing
> malicious activities.  Thanks to  ptrace_may_access(), various part of
> the kernel can check if a tracer is more privileged than a tracee.
> 
> A landlocked process has fewer privileges than a non-landlocked process
> and must then be subject to additional restrictions when manipulating
> processes. To be allowed to use ptrace(2) and related syscalls on a
> target process, a landlocked process must have a subset of the target
> process's rules (i.e. the tracee must be in a sub-domain of the tracer).
> 
> Cc: James Morris <jmorris@namei.org>
> Cc: Kees Cook <keescook@chromium.org>
> Signed-off-by: Micka?l Sala?n <mic@linux.microsoft.com>

Reviewed-by: Kees Cook <keescook@chromium.org>

-- 
Kees Cook