linux-kernel - Re: 2.6.25 Kernel - Problems with capabilities

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Message-ID: <20080421000055.GA17510@vino.hallyn.com>
Date:	Sun, 20 Apr 2008 19:00:55 -0500
From:	serge@...lyn.com
To:	David <david@...olicited.net>
Cc:	casey@...aufler-ca.com, Mike Galbraith <efault@....de>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Andrew Morgan <morgan@...nel.org>
Subject: Re: 2.6.25 Kernel - Problems with capabilities

Quoting David (david@...olicited.net):
> Casey Schaufler wrote:
>> Do you have a libcap that reflects the change from 32 capabilities
>> to 64? You'll be looking for libcap.so.2.06 or thereabouts.
>>   
> Adding libcap-2.08 and recompiling ntpd has fixed the issue, and I'm now 
> running normally, thanks!

I don't understand why, though.  Looking at the ntpd code (ntp-4.2.4p4)
it just does a cap_set_proc(cap_from_text("X=epi"));  It should simply
be sending in the _LINUX_CAPABILITY_VERSION which shipped with libcap,
which should have been _V1, and the kernel should honor that so long as
you didn't try to send in caps > 31, which ntpd wasn't.

> Was this userspace visible change planned in advance for 2.6.25 ? ... as I 
> guess a few other people with venerable old userspace components may come 
> across this issue.
>
> Cheers
> David

It's been in the works a long time and we thought we'd done pretty
well with backward compatibility.  I really don't see why you had
that failure!

Do you know which version of libcap you had before?

thanks,
-serge
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