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Date: Mon, 16 Nov 2020 22:36:17 +0100
From: Mickaël Salaün <mic@...ikod.net>
To: Pavel Machek <pavel@....cz>
Cc: James Morris <jmorris@...ei.org>, "Serge E . Hallyn" <serge@...lyn.com>,
Al Viro <viro@...iv.linux.org.uk>, Andy Lutomirski <luto@...capital.net>,
Anton Ivanov <anton.ivanov@...bridgegreys.com>, Arnd Bergmann
<arnd@...db.de>, Casey Schaufler <casey@...aufler-ca.com>,
Jann Horn <jannh@...gle.com>, Jeff Dike <jdike@...toit.com>,
Jonathan Corbet <corbet@....net>, Kees Cook <keescook@...omium.org>,
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 v22 01/12] landlock: Add object management
On 16/11/2020 22:26, Pavel Machek wrote:
> Hi!
>
>> A Landlock object enables to identify a kernel object (e.g. an inode).
>> A Landlock rule is a set of access rights allowed on an object. Rules
>> are grouped in rulesets that may be tied to a set of processes (i.e.
>> subjects) to enforce a scoped access-control (i.e. a domain).
>>
>> Because Landlock's goal is to empower any process (especially
>> unprivileged ones) to sandbox themselves, we cannot rely on a
>> system-wide object identification such as file extended attributes.
>
>
>> +config SECURITY_LANDLOCK
>> + bool "Landlock support"
>> + depends on SECURITY
>> + select SECURITY_PATH
>> + help
>> + Landlock is a safe sandboxing mechanism which enables processes to
>> + restrict themselves (and their future children) by gradually
>> + enforcing tailored access control policies. A security policy is a
>> + set of access rights (e.g. open a file in read-only, make a
>> + directory, etc.) tied to a file hierarchy. Such policy can be configured
>> + and enforced by any processes for themselves thanks to dedicated system
>> + calls: landlock_create_ruleset(), landlock_add_rule(), and
>> + landlock_enforce_ruleset_current().
>
> How does it interact with setuid binaries? Being able to exec passwd
> in a sandbox sounds like ... fun way to get root? :-).
It works like seccomp: if you run with CAP_SYS_ADMIN in the current
namespace, then SUID binaries may be allowed, otherwise if you use
PR_SET_NO_NEW_PRIVS, then executing a SUID binary is denied.
The 24th version is here:
https://lore.kernel.org/lkml/20201112205141.775752-1-mic@digikod.net/
>
> Best regards,
> Pavel
>
>
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