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Date: Thu, 26 Feb 2015 09:35:24 -0600
From: "Serge E. Hallyn" <serge@hallyn.com>
To: Christoph Lameter <cl@linux.com>
Cc: Serge Hallyn <serge.hallyn@ubuntu.com>,
        "Serge E. Hallyn" <serge@hallyn.com>,
        Serge Hallyn <serge.hallyn@canonical.com>,
        Andy Lutomirski <luto@amacapital.net>,
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Subject: Re: [PATCH] capabilities: Ambient capability set V1
Message-ID: <20150226153524.GC15182@mail.hallyn.com>
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On Wed, Feb 25, 2015 at 02:25:19PM -0600, Christoph Lameter wrote:
> On Wed, 25 Feb 2015, Serge Hallyn wrote:
> 
> > Yeah we could make this
> 
> Well doing that breaks su.

Don't what exactly?  You're saying that doing

pI' = pI
pA' = pA  (pA is ambient)
pP' = (X & fP) | (pI & (fI | pA))
pE' = pP' & (fE | pA)

stopped su from having CAP_SETGID while

pI' = pI
pA' = pA  (pA is ambient)
pP' = (X & fP) | (pI & (fI | pA))
pE' = pP' & fE

worked?  I'll hope you're saying both "fail", in which case

> Its best to leave perm bits untouched.


> christoph@fujitsu-haswell:~$ su
> setgid: Operation not permitted

Did you initialize by running a program to fill your pI?

-serge