9:52 a.m.
On Wed, 2013-04-03 at 10:36 -0400, Abhishek Koneru wrote:
Hi Ade,
Please share your views on this. It is regarding a ticket to prevent a
concurrent execution of pkispawn/pkidestroy.
On Tue, 2013-04-02 at 15:52 -0500, Endi Sukma Dewata wrote:
On 4/2/2013 11:54 AM, Abhishek Koneru wrote:
> Please review the patch which adds a locking mechanism to prevent
> pkispawn and pkidestroy to execute concurrently.
Some comments:
1. This mechanism locks the entire system, so only one
pkispawn/pkidestroy can run at any time. Is this the intended behavior?
Or should we lock a particular instance only?
I think it was decided to allow only one pkispawn/pkidestroy for an
entire system.
pkispawn and pkidestroy do selinux operations. Only one set of selinux
operations should be done at a time. Not doing this could cause an
operation to fail or worse. If you like, you could try to lock this
section only, but then you still need to ensure that concurrent
oerations do not affect the same data -- for instance, are they touching
the same ports?
The simplest and easiest solution will be to lock to having one
operation per system at a time.
2. If another script is already running, the current script will block
until the other script is done. Is this the intended behavior? Or should
it fail immediately? Or should it wait but show a message saying another
script is running?
Since only the section of code which does spawn()/destroy() are under
lock, all the user details are taken by that time. But the blocked
script will be waiting for some-time. I think showing a message would be
nice as Endi reviewed.
My first thought was that it should fail immediately. But I could see
having it wait with the relevant message. The user can then choose to
control-C if they want.
3. Right now the lock file is called /tmp/pkioperationlock.lck. It
might
be better to move it into /var/run/pki/pki-deployment.lock or something
like that.
Will be changed.
PFA the patch for you convenience.
--Abhishek
10:56 a.m.
New subject: [PATCH] 46 Prevent concurrent execution of pkispawn and pkidestroy
On 4/3/2013 9:52 AM, Ade Lee wrote:
On Wed, 2013-04-03 at 10:36 -0400, Abhishek Koneru wrote:
> 1. This mechanism locks the entire system, so only one
> pkispawn/pkidestroy can run at any time. Is this the intended behavior?
> Or should we lock a particular instance only?
>
> I think it was decided to allow only one pkispawn/pkidestroy for an
> entire system.
pkispawn and pkidestroy do selinux operations. Only one set of selinux
operations should be done at a time. Not doing this could cause an
operation to fail or worse. If you like, you could try to lock this
section only, but then you still need to ensure that concurrent
oerations do not affect the same data -- for instance, are they touching
the same ports?
The simplest and easiest solution will be to lock to having one
operation per system at a time.
Is it because the selinux operations in general are not safe to run
concurrently? If that's the case what about selinux operations executed
by other applications, do we need to be concerned about that?
Or is this only a concern when the operations affect the same data (e.g.
same instance/ports)? This means running concurrent pkispawn to create
two unrelated instances with completely different settings should not be
blocked at all.
If that's the case, there are two things that can be done:
1. Lock the instance to make sure it's not modified at the same time.
2. Check to make sure different instances don't use conflicting settings
(e.g. ports).
In general we should be able to assume that people won't use conflicting
settings in different instances. But if that happens the above steps
should catch that. Does setup-ds.pl lock the entire system?
Locking pkispawn/pkidestroy to prevent concurrent execution doesn't
really prevent someone from using conflicting settings in a later execution.
--
Endi S. Dewata
4061
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Endi Sukma Dewata