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From
SubjectRe: ext2 attribute immutable
Date
Followup to:  <24376.199604030736@stone.dcs.warwick.ac.uk>
By author: Zefram <A.Main@dcs.warwick.ac.uk>
In newsgroup: linux.dev.kernel
>
> >> So, how does one need to modify /proc/1/mem to decrease the secure-level
> >> after getting root access? :)
> >
> >You don't need to. You can just do a ptrace() on init, or create your
> >OWN init process --- by using a careful, controlled fork bomb we can
> >easily create new processes until we are about to wrap pid, then kill
> >init and wait until one of our forks has a pid of 1.
>
> The fork attack shouldn't be possible. On SunOS, for example, when the
> PIDs wrap, they wrap to 101, not 1. Doesn't Linux do something like
> this? If it wraps to 1, this has to change -- conceptually, low PIDs
> are a privileged resource, so access to them must be restricted.
>

Baloney. If init exits, the kernel will automatically spawn a new one
(Linux); most other OSes will treat init exiting as evidence of a
fatal crash and panic/reboot. Not only can't you kill init, but you
can't replace it by any less than changing the binary.

-hpa

--
PGP public key available - finger hpa@zytor.com
"The earth is but one country, and mankind its citizens." -- Bahá'u'lláh
I don't work for Yggdrasil, but they sponsor the linux.* hierarchy.


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