Re: FreeBSD VM gremlin

[imp () VILLAGE ORG (Warner Losh)]

In message <199809181149.HAA21721 () lunacity ne mediaone net> "Charles
M. Hannum" writes:
:
: > You should have md5 checksums of files that you are concerned about,
: > as timestamps are useless in the face of a good attacker.
:
: Rubbish!  A checksum doesn't tell me that someone hadn't temporarily
: replaced the file and has now put the original back.

Ummm, you still can't tell that for a competant attacker.  A good
attacker can set the system time, frob the file, set it back let time
pass and then do the same thing to get the original back.  You'd never
know.

It is a bug in the FreeBSD VM system where a page gets marked as
dirty, but the underlying pages are hardware protected against write,
so the same contents are written out.

Warner