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

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Message-ID: <87leyhyzqe.fsf@email.froward.int.ebiederm.org>
Date:   Fri, 11 Feb 2022 13:23:05 -0600
From:   "Eric W. Biederman" <ebiederm@...ssion.com>
To:     Shuah Khan <skhan@...uxfoundation.org>
Cc:     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>,
        Michal Koutný <mkoutny@...e.com>
Subject: Re: [PATCH 0/8] ucounts: RLIMIT_NPROC fixes

Shuah Khan <skhan@...uxfoundation.org> writes:

> On 2/10/22 7:01 PM, Eric W. Biederman wrote:
>> Michal Koutný recently found some bugs in the enforcement of
>> RLIMIT_NPROC in the recent ucount rlimit implementation.
>> I saw some additional bugs and some cleaner ways to fix the problem so
>> instead of starting with his fixes these are my own.
>> I am aiming to send the first 5 of these to Linus once they have been
>> reviewed.  Two more are fixes in principle but I don't think do anything
>> in practice.  The last one is just a cleanup to prevent future
>> divergence of RLIMIT_NPROC logic.
>> Eric W. Biederman (8):
>>        ucounts: Fix RLIMIT_NPROC regression
>>        ucounts: Fix set_cred_ucounts
>>        ucounts: Fix and simplify RLIMIT_NPROC handling during setuid()+execve
>>        ucounts: Only except the root user in init_user_ns from RLIMIT_NPROC
>
> Should this be "Only exempt"?

Yes.
>  >        ucounts: Handle wrapping in is_ucounts_overlimit
>>        ucounts: Handle inc_rlimit_ucounts wrapping in fork
>>        rlimit: For RLIMIT_NPROC test the child not the parent for capabilites
>>        ucounts: Use the same code to enforce RLIMIT_NPROC in fork and exec
>>   fs/exec.c                    | 12 +++++-------
>>   include/linux/sched.h        |  2 +-
>>   include/linux/sched/signal.h |  2 ++
>>   kernel/cred.c                | 24 +++++++++++-------------
>>   kernel/fork.c                | 32 ++++++++++++++++++++++++--------
>>   kernel/sys.c                 | 14 --------------
>>   kernel/ucount.c              |  3 ++-
>>   kernel/user_namespace.c      |  2 ++
>>   8 files changed, 47 insertions(+), 44 deletions(-)
>> Eric
>> 
>
> Do we need updates to selftests - Michal's patch series included changes to
> selftests/exec

selftests would be good.

Eric