Re: [PATCH -mm 5/7] add user namespace

Eric W. Biederman
2006-07-14T03:51:50Z

"Serge E. Hallyn" <serue@us.ibm.com> writes:

> Quoting Eric W. Biederman (ebiederm@xmission.com):
>> >> keys are essentially security credentials for something besides the
>> >> local kernel. Think kerberos tickets. That makes the keys the
>> >> obvious place to say what uid you are in a different user namespace
>> >> and similar things.
>> >
>> > what about performance ? wouldn't that slow the checking ?
>>
>> It needs to be looked at, but it shouldn't slow the same namespace
>> case,
>
> How so? The processesing is the same.

If you do mapping of uids that would not trigger if you have
matching user namespaces.

>> and permission checking is largely a slow path issue. So a little
>> overhead at open time is preferred to overhead after you get the file
>> open.
>
> Unsure which approach has overhead after file open...

I don't know that I have seen that one yet. Sorry this was generally
a statement of principle.

Eric