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Thread-Topic: [PATCH] opcache bug #69090, prepend user identifier to keys
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Date: Thu, 10 Nov 2016 08:51:58 +0000
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Subject: Re: [PATCH] opcache bug #69090, prepend user identifier to keys
From: dmitry@zend.com (Dmitry Stogov)

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Hi,


sorry for delay. I've traveled.


I see the problem(s) and I took a look into the patch.


From the first look, I don't like the proposed solution.

It makes things a bit better, but can't solve shared-hosting configuration =
problems.

It doesn't solve even the simple chroot file resolution problem in general =
(one user ma have few chroot environments with conflicting file names).

I'm not sure, if it's possible to make chroot on Windows, so why we need to=
 add windows user names?

The patch introduces syscall in the hot function (this may be optimized).


I'm open for discussion and may change my mind. I'll also try to find a bet=
ter solution. Any suggestions are welcome.


Thanks. Dmitry.



________________________________
From: php-dev@coydogsoftware.net <php-dev@coydogsoftware.net>
Sent: Friday, November 4, 2016 2:00:03 PM
To: internals@lists.php.net
Cc: Dmitry Stogov
Subject: [PATCH] opcache bug #69090, prepend user identifier to keys

Hello,

I'm CCing Dmitry Stogov as maintainer because he's listed as an author
in ext/opcache/ZendAccelerator.c and has recent commits.

I've attached a patch for bug #69090. You can find a more detailed
writeup at https://bugs.php.net/bug.php?id=3D69090 . In short, the patch
adds EUID or Windows username at the beginning of OPCache keys to
prevent cross-user cache access, which will hopefully alleviate security
concerns of enabling OPCache on shared hosting servers.

I took this in a different direction than that proposed in bug #69090
(prepending inode to key) because I feel it more effectively addresses
the cross-user security concerns.

I don't have a test script yet because the change is transparent to
scripts, but I could probably cobble one together by checking OPCache
debug log for key names. I do intend to port this forward to PHP7 head,
but in my opinion the existing behavior in 5.6 is a serious
vulnerability which warrants a maintenance patch. If needed I can
provide working exploit scripts to demonstrate how bad the existing
behavior is for shared servers using OPCache.

I was hoping to get some feedback before I put in the effort to port
this to PHP7.

Thanks,
--
- php-dev@coydogsoftware.net

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