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.