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From: "Eric W. Biederman" <ebiederm@xmission.com>
To: Paul Moore <paul@paul-moore.com>
Cc: Frederick Lawler <fred@cloudflare.com>,
	kpsingh@kernel.org, revest@chromium.org, jackmanb@chromium.org,
	ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org,
	kafai@fb.com, songliubraving@fb.com, yhs@fb.com,
	john.fastabend@gmail.com, jmorris@namei.org, serge@hallyn.com,
	stephen.smalley.work@gmail.com, eparis@parisplace.org,
	shuah@kernel.org, brauner@kernel.org, casey@schaufler-ca.com,
	bpf@vger.kernel.org, linux-security-module@vger.kernel.org,
	selinux@vger.kernel.org, linux-kselftest@vger.kernel.org,
	linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
	kernel-team@cloudflare.com, cgzones@googlemail.com,
	karl@bigbadwolfsecurity.com
Subject: Re: [PATCH v4 0/4] Introduce security_create_user_ns()
Date: Mon, 08 Aug 2022 14:43:41 -0500	[thread overview]
Message-ID: <87bksu8qs2.fsf@email.froward.int.ebiederm.org> (raw)
In-Reply-To: <877d3ia65v.fsf@email.froward.int.ebiederm.org> (Eric W. Biederman's message of "Mon, 08 Aug 2022 14:26:04 -0500")

"Eric W. Biederman" <ebiederm@xmission.com> writes:

> Paul Moore <paul@paul-moore.com> writes:
>
>>> I did provide constructive feedback.  My feedback to his problem
>>> was to address the real problem of bugs in the kernel.
>>
>> We've heard from several people who have use cases which require
>> adding LSM-level access controls and observability to user namespace
>> creation.  This is the problem we are trying to solve here; if you do
>> not like the approach proposed in this patchset please suggest another
>> implementation that allows LSMs visibility into user namespace
>> creation.
>
> Please stop, ignoring my feedback, not detailing what problem or
> problems you are actually trying to be solved, and threatening to merge
> code into files that I maintain that has the express purpose of breaking
> my users.
>
> You just artificially constrained the problems, so that no other
> solution is acceptable.  On that basis alone I am object to this whole
> approach to steam roll over me and my code.

If you want an example of what kind of harm it can cause to introduce a
failure where no failure was before I invite you to look at what
happened with sendmail when setuid was modified to fail, when changing
the user of a process would cause RLIMIT_NPROC to be exceeded.

I am not arguing that what you are proposing is that bad but unexpected
failures cause real problems, and at a minimum that needs a better
response than: "There is at least one user that wants a failure here".

Frankly I would love to see an argument that semantically it ever makes
sense for creating a user namespace to fail.  If that argument has
already been made, my apologies to the person who made as I missed it,
in being sick and tired, and frustrated at being blown off, when
I asked for a proper discuss of the problem at hand.

Eric


  reply	other threads:[~2022-08-08 19:43 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-08-01 18:01 [PATCH v4 0/4] Introduce security_create_user_ns() Frederick Lawler
2022-08-01 18:01 ` [PATCH v4 1/4] security, lsm: " Frederick Lawler
2022-08-02 21:47   ` KP Singh
2022-08-03 13:13     ` Frederick Lawler
2022-08-01 18:01 ` [PATCH v4 2/4] bpf-lsm: Make bpf_lsm_userns_create() sleepable Frederick Lawler
2022-08-01 23:00   ` Alexei Starovoitov
2022-08-01 23:06     ` Paul Moore
2022-08-02 21:29   ` KP Singh
2022-08-01 18:01 ` [PATCH v4 3/4] selftests/bpf: Add tests verifying bpf lsm userns_create hook Frederick Lawler
2022-08-02 22:08   ` KP Singh
2022-08-01 18:01 ` [PATCH v4 4/4] selinux: Implement " Frederick Lawler
2022-08-02  2:56 ` [PATCH v4 0/4] Introduce security_create_user_ns() Eric W. Biederman
2022-08-03  2:10   ` Paul Moore
2022-08-08 18:56     ` Eric W. Biederman
2022-08-08 19:16       ` Paul Moore
2022-08-08 19:26         ` Eric W. Biederman
2022-08-08 19:43           ` Eric W. Biederman [this message]
2022-08-08 22:47             ` Paul Moore
2022-08-09 16:07               ` Eric W. Biederman
2022-08-09 16:47                 ` Paul Moore
2022-08-09 21:40                   ` Eric W. Biederman
2022-08-09 22:40                     ` Paul Moore
2022-08-10  0:51                       ` Alexei Starovoitov
2022-08-09 17:43                 ` Casey Schaufler
2022-08-09 21:52                   ` Eric W. Biederman
2022-08-08 19:49           ` Paul Moore
2022-08-09 16:40             ` Eric W. Biederman
2022-08-14 15:55         ` Serge E. Hallyn
2022-08-15  2:32           ` Paul Moore
2022-08-15 15:41             ` Serge E. Hallyn
2022-08-15 16:24               ` Paul Moore

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