linux-kernel - Re: [PATCH 0/8] ucounts: RLIMIT

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: <20220215113748.GI21589@blackbody.suse.cz>
Date:   Tue, 15 Feb 2022 12:37:48 +0100
From:   Michal Koutný <mkoutny@...e.com>
To:     Shuah Khan <skhan@...uxfoundation.org>
Cc:     "Eric W. Biederman" <ebiederm@...ssion.com>,
        linux-kernel@...r.kernel.org, Alexey Gladkov <legion@...nel.org>,
        Kees Cook <keescook@...omium.org>,
        Shuah Khan <shuah@...nel.org>,
        Christian Brauner <brauner@...nel.org>,
        Solar Designer <solar@...nwall.com>,
        Ran Xiaokai <ran.xiaokai@....com.cn>,
        Linux Containers <containers@...ts.linux-foundation.org>
Subject: Re: [PATCH 0/8] ucounts: RLIMIT_NPROC fixes

On Fri, Feb 11, 2022 at 11:22:13AM -0700, Shuah Khan <skhan@...uxfoundation.org> wrote:
> Do we need updates to selftests - Michal's patch series included changes to
> selftests/exec

In my understanding the original rlimits-per-userns.c covers an invalid
use case -- clone(0);setuid();unshare(CLONE_NEWUSER) -- where the
created user_ns is owned by unprivileged user and the global
RLIMIT_NPROC cannot be breached.

My patched variant retains this use-case (should fail) and adds
clone(CLONE_NEWUSER);setuid() [1] variant which should be the valid
use-case for per-user per-user-ns RLIMIT_NPROC.

Michal

[1] In this situation theoretically equivalent to clone(0);unshare(CLONE_NEWUSER);setuid().