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Date:      Thu, 1 Sep 2005 00:21:05 +0400 (MSD)
From:      Michael Bushkov <bushman@rsu.ru>
To:        Brooks Davis <brooks@one-eyed-alien.net>
Cc:        freebsd-current@freebsd.org, Dan Nelson <dnelson@allantgroup.com>, Jilles Tjoelker <jilles@stack.nl>
Subject:   Re: [PATCH] caching daemon release and nsswitch patches
Message-ID:  <20050901001719.Q72814@stinger.cc.rsu.ru>
In-Reply-To: <20050831201116.GH32477@odin.ac.hmc.edu>
References:  <20050827170633.Y5409@stinger.cc.rsu.ru> <43123F3B.8070002@FreeBSD.org> <20050829115740.N5409@stinger.cc.rsu.ru> <20050829163025.GA25664@dan.emsphone.com> <20050830172127.E5409@stinger.cc.rsu.ru> <20050831190059.GA23652@stack.nl> <20050831231233.T72814@stinger.cc.rsu.ru> <20050831194808.GA12742@stack.nl> <20050831235458.L72814@stinger.cc.rsu.ru> <20050831201116.GH32477@odin.ac.hmc.edu>

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Hello!

>>> User X puts some garbled information in the cache for his uid, then
>>> starts a setgid program. That setgid program will use the bad data
>>> in the cache which is potentially exploitable.
>> Yes - you're right. I see 2 solutions:
>>
>> 1) The thing that you said - to turn off the caching for set*id programs
>>
>> 2) To separate users in the cache not only by their euid, but by their
>> euid and egid together. In this case, if user X poisons the cache and
>> starts the setgid program, then it will use the different (not poisoned)
>> cache. I don't think that such a partitioning will cause the cache to grow
>> too much.
>
> I'd be inclined toward the first option.  Getting edge cases right for
> suid apps requires lots of thinking so I'd rather just not support the
> feature initially.  Performance critical suid applications probably
> aren't too common anyway.

Ok - I'm absolutely agreed. I'll do it this way.

With best regards,
Michael Bushkov
Rostov State University



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