From: Frederick Lawler <fred@cloudflare.com>
To: Paul Moore <paul@paul-moore.com>
Cc: 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,
ebiederm@xmission.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
Subject: Re: [PATCH v2 4/4] selinux: Implement create_user_ns hook
Date: Wed, 20 Jul 2022 09:57:53 -0500 [thread overview]
Message-ID: <42069251-3ea7-b0c7-4efb-e144c52ebf51@cloudflare.com> (raw)
In-Reply-To: <CAHC9VhTkvPvqGQjyEKbi2pkKBtRQE=Uat34aoKsxjWU0qkF6CA@mail.gmail.com>
On 7/19/22 8:32 PM, Paul Moore wrote:
> On Thu, Jul 7, 2022 at 6:32 PM Frederick Lawler <fred@cloudflare.com> wrote:
>>
>> Unprivileged user namespace creation is an intended feature to enable
>> sandboxing, however this feature is often used to as an initial step to
>> perform a privilege escalation attack.
>>
>> This patch implements a new namespace { userns_create } access control
>> permission to restrict which domains allow or deny user namespace
>> creation. This is necessary for system administrators to quickly protect
>> their systems while waiting for vulnerability patches to be applied.
>>
>> This permission can be used in the following way:
>>
>> allow domA_t domB_t : namespace { userns_create };
>>
>> Signed-off-by: Frederick Lawler <fred@cloudflare.com>
>>
>> ---
>> Changes since v1:
>> - Introduce this patch
>> ---
>> security/selinux/hooks.c | 9 +++++++++
>> security/selinux/include/classmap.h | 2 ++
>> 2 files changed, 11 insertions(+)
>>
>> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
>> index beceb89f68d9..73fbcb434fe0 100644
>> --- a/security/selinux/hooks.c
>> +++ b/security/selinux/hooks.c
>> @@ -4227,6 +4227,14 @@ static void selinux_task_to_inode(struct task_struct *p,
>> spin_unlock(&isec->lock);
>> }
>>
>> +static int selinux_userns_create(const struct cred *cred)
>> +{
>> + u32 sid = current_sid();
>> +
>> + return avc_has_perm(&selinux_state, sid, sid, SECCLASS_NAMESPACE,
>> + NAMESPACE__USERNS_CREATE, NULL);
>> +}
>
> As we continue to discuss this, I'm beginning to think that having a
> dedicated object class for the userns might be a good idea. I believe
> I was the one who gave you these code snippets, so feel free to blame
> me for the respin ;)
>
No worries, I'll make this change for v3.
> This is what I'm thinking:
>
> static int selinux_userns_create(const struct cred *cred)
> {
> u32 sid = current_sid();
>
> return avc_has_perm(&selinux_state, sid, sid,
> SECCLASS_USER_NAMESPACE,
> USER_NAMESPACE__CREATE, NULL);
> }
>
>> diff --git a/security/selinux/include/classmap.h b/security/selinux/include/classmap.h
>> index ff757ae5f253..9943e85c6b3e 100644
>> --- a/security/selinux/include/classmap.h
>> +++ b/security/selinux/include/classmap.h
>> @@ -254,6 +254,8 @@ const struct security_class_mapping secclass_map[] = {
>> { COMMON_FILE_PERMS, NULL } },
>> { "io_uring",
>> { "override_creds", "sqpoll", NULL } },
>> + { "namespace",
>> + { "userns_create", NULL } },
>
> The above would need to change to:
>
> { "user_namespace",
> { "create", NULL } }
>
next prev parent reply other threads:[~2022-07-20 14:58 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-07 22:32 [PATCH v2 0/4] Introduce security_create_user_ns() Frederick Lawler
2022-07-07 22:32 ` [PATCH v2 1/4] security, lsm: " Frederick Lawler
2022-07-07 22:32 ` [PATCH v2 2/4] bpf-lsm: Make bpf_lsm_create_user_ns() sleepable Frederick Lawler
2022-07-07 22:32 ` [PATCH v2 3/4] selftests/bpf: Add tests verifying bpf lsm create_user_ns hook Frederick Lawler
2022-07-07 22:32 ` [PATCH v2 4/4] selinux: Implement " Frederick Lawler
2022-07-20 1:32 ` Paul Moore
2022-07-20 14:57 ` Frederick Lawler [this message]
[not found] ` <CA+EEuAhfMrg=goGhWxVW2=i4Z7mVN4GvfzettvX8T+tFcOPKCw@mail.gmail.com>
2022-07-20 14:52 ` Paul Moore
2022-07-08 12:10 ` [PATCH v2 0/4] Introduce security_create_user_ns() Christian Göttsche
2022-07-08 14:01 ` Frederick Lawler
2022-07-08 14:35 ` Christian Brauner
2022-07-08 16:11 ` Casey Schaufler
2022-07-14 14:27 ` Serge E. Hallyn
2022-07-19 19:59 ` Frederick Lawler
2022-07-20 1:32 ` Paul Moore
2022-07-20 21:42 ` Casey Schaufler
2022-07-20 22:39 ` Paul Moore
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