Re: [PATCH] capabilities: Ambient capability set V1

From: Christoph Lameter
Date: Mon Feb 23 2015 - 11:44:40 EST

On Mon, 23 Feb 2015, Serge Hallyn wrote:

> The core concern for amorgan is that an unprivileged user not be
> able to cause a privileged program to run in a way that it fails to
> drop privilege before running unprivileged-user-provided code.

I do not see a problem with dropping privilege since the ambient set
is supposed to be preserved across a drop of priviledge.

> Since your desire is precisely for a mode where dropping privilege
> works as usual, but exec then re-gains some or all of that privilege,

I would say that the ambient set stays active even if the setuid binary
drops to regular perms.

> we need to either agree on a way to enter that mode that ordinary
> use caes can't be tricked into using, or find a way for legacy
> users to be tpiped off as to what's going on (without having to be
> re-written)

Well if the ambient set is completely separate then the existing
semantics are preserved while the ambient set stays active as intended.

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