Re: [PATCH v10] LSM: Multiple concurrent LSMs

[Casey Schaufler <casey@schaufler-ca.com>]

On 12/12/2012 9:47 AM, Eric Paris wrote:
> On Wed, Dec 12, 2012 at 12:31 PM, Casey Schaufler
> <casey@schaufler-ca.com> wrote:
>
>> We can't undo the sins of the past regarding /proc/.../attr.
> Agreed
>
>> With
>> the scheme I'm putting forth you can have a working system with both
>> SELinux and AppArmor if either runtime understands the multiple LSM
>> environment.
> Agreed.  (assuming the command line option was configured to present
> the one that doesn't understand)
>
>> If neither understands, at least one will have trouble.
> Agreed.  I'm just of the belief the 'trouble' should be 'fails
> completely' rather than 'fails partially' trying to use
> /proc/self/attr...

Configure None as the presented LSM and all legacy userspace
will fail. Trouble for all.

>
>> On a slightly different note, do we need a liblsm with interfaces like:
>>
>>         int lsm_presented(char *presented)
>>         int lsm_supported(char *lsmname)
>>
>> so you're not reading the files directly?
> If I have new enough userspace to call such functions, do I need them?
>  Doesn't seem I need presented.  I can always use the selinux.*
> version of attr files.  Maybe lsm_supported is slightly useful.  We
> don't have to parse /proc/filesystems looking for selinuxfs.  I guess
> that'd be faster, but I don't know if others would use it...
>
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