linux-kernel - Re: [PATCH v30 04/12] landlock: Add ptrace restrictions

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Date:   Fri, 19 Mar 2021 11:45:38 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Mickaël Salaün <mic@...ikod.net>
Cc:     James Morris <jmorris@...ei.org>, Jann Horn <jannh@...gle.com>,
        "Serge E . Hallyn" <serge@...lyn.com>,
        Al Viro <viro@...iv.linux.org.uk>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andy Lutomirski <luto@...capital.net>,
        Anton Ivanov <anton.ivanov@...bridgegreys.com>,
        Arnd Bergmann <arnd@...db.de>,
        Casey Schaufler <casey@...aufler-ca.com>,
        David Howells <dhowells@...hat.com>,
        Jeff Dike <jdike@...toit.com>,
        Jonathan Corbet <corbet@....net>,
        Michael Kerrisk <mtk.manpages@...il.com>,
        Richard Weinberger <richard@....at>,
        Shuah Khan <shuah@...nel.org>,
        Vincent Dagonneau <vincent.dagonneau@....gouv.fr>,
        kernel-hardening@...ts.openwall.com, linux-api@...r.kernel.org,
        linux-arch@...r.kernel.org, linux-doc@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-kselftest@...r.kernel.org,
        linux-security-module@...r.kernel.org, x86@...nel.org,
        Mickaël Salaün <mic@...ux.microsoft.com>
Subject: Re: [PATCH v30 04/12] landlock: Add ptrace restrictions

On Tue, Mar 16, 2021 at 09:42:44PM +0100, Mickaël Salaün wrote:
> From: Mickaël Salaün <mic@...ux.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@...ei.org>
> Cc: Kees Cook <keescook@...omium.org>
> Signed-off-by: Mickaël Salaün <mic@...ux.microsoft.com>

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

-- 
Kees Cook