[PATCH v2 1/3] LSM: Add new hook for generic node initialization

[Casey Schaufler]

On 1/10/2019 5:57 PM, Paul Moore wrote:
> On Wed, Jan 9, 2019 at 12:08 PM Casey Schaufler <casey at schaufler-ca.com> wrote:
>> On 1/9/2019 8:28 AM, Ondrej Mosnacek wrote:
>>> This patch introduces a new security hook that is intended for
>>> initializing the security data for newly created pseudo filesystem
>>> objects (such as kernfs nodes) that provide a way of storing a
>>> non-default security context, but need to operate independently from
>>> mounts.
>>>
>>> The main motivation is to allow kernfs nodes to inherit the context of
>>> the parent under SELinux, similar to the behavior of
>>> security_inode_init_security(). Other LSMs may implement their own logic
>>> for handling the creation of new nodes.
>>>
>>> Signed-off-by: Ondrej Mosnacek <omosnace at redhat.com>
>>> ---
>>>  include/linux/lsm_hooks.h | 30 ++++++++++++++++++++++++++++++
>>>  include/linux/security.h  | 14 ++++++++++++++
>>>  security/security.c       | 10 ++++++++++
>>>  3 files changed, 54 insertions(+)
>>>
>>> diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
>>> index aaeb7fa24dc4..3a2399d7721f 100644
>>> --- a/include/linux/lsm_hooks.h
>>> +++ b/include/linux/lsm_hooks.h
>>> @@ -429,6 +429,31 @@
>>>   *   to abort the copy up. Note that the caller is responsible for reading
>>>   *   and writing the xattrs as this hook is merely a filter.
>>>   *
>>> + * Security hooks for special file-like objects
>>> + *
>>> + * @object_init_security:
>> I don't like the name. There are too many things that are "objects"
>> for this to be meaningful. I also dislike seeing names like
>> security_object_init_security. How about init_from_parent? If there's
>> never a chance that it will be used anywhere but with kernfs, it could
>> be kernfs_node_init. The existing set of hook names are sufficiently
>> confusing without adding to the mystery.
> I like the naming similarity with inode_init_security(), that seems
> helpful.  Although I somewhat understand you concern about the generic
> "object".  Could you live with kernfs_init_security()?  If another fs
> adopts it, we could always changing the name later if needed.

I can live with it as is, but kernfs_init_security would
be better. The security_blah_security names seem crazy to
me, but changing object to kernfs is really what's important.