Messages in this thread | | | From | David Howells <> | Subject | Re: [PATCH -mm] Revoke core code: fix nommu arch compiling error bug | Date | Mon, 26 Mar 2007 14:24:38 +0100 |
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Pekka J Enberg <penberg@cs.helsinki.fi> wrote:
> We don't touch private mappings at all as they're a snapshot to the inode > _before_ it was revoked. So private mappings don't really matter all: you > don't see any new data after it has been revoked nor do you flush anything > to the disk.
Okay, so that's not a problem.
> Well, assuming we would use revoke for things like SAK, this doesn't > really work out too well because all a malicious process has to is create > a shared mapping and they've effectively blocked the whole thing.
In NOMMU-mode, there's probably[*] nothing stopping a malicious process running completely amok and changing stuff directly - even the kernel isn't guaranteed to be safe - so I wouldn't worry about such a case.
[*] The FRV, for example, does have some limited protection capability - but it is really limited and not really useful in this case.
> It's antisocial for sure but the only way to guarantee revoke() succeeds on > a NOMMU setup. Oh well, lets disable it for now and see if anyone even > wants revoke() for NOMMU.
Agreed.
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