Re: [malware-list] [RFC 0/5] [TALPA] Intro to a linux interfaceforonaccess scanning

[David Collier-Brown]

Peter Dolding wrote:
> My main issue is TALPA, dazuko and so on of Anti-Virus Filesystem
> monitoring are all going to break anyhow when
> http://lwn.net/Articles/251224/ Credentials get added and common
> filesystem caching gets added.
>
> You want to change a permissions on a file/object before its opened.
> So does the Credential user space daemon on file systems that cannot
> store secuirty information.  We only really need 1 location in the
> source base for this.  Expand Credentials slightly to allow anti
> viruses to operate by by problem.   Even better when FS-Cache can sit
> on top of Credentials correctly no need for anti virus software to
> have independent caching of blocked and allowed files.  FS-Cache picks
> a large amount of this up.
>
> Basically TALPA, dazuko and so on of Anti-Virus Filesystem monitoring
> don't fit in the future design of Linux.   All they will be is
> duplication of a existing interface.  A interface that complete avoids
> the stacking issue.

Then in a real sense you've solved much of their problem for them (;-))
After this comes engineering, so that they can re-use the scanning 
mechanisms they already have, but from a different caller.

The requirements are probably that they know
- is this an open for read or write (somewhat less time-sensitive)?
- is the data present, or do we have to wait?
- if so, for what?
as of the time they start looking at the file.  Having a race-free
mechanism using credentials and RCU is, IMHO, A Really Good Thing.

Another thing they and we will likely need is a way to discover
if a file is inacessable due to an AV operation, and if the time
it has been inacessable is less than or equal to a scanning
upper bound by file size or beyond it.  The latter is for repair
of broken state introduced by the AV process failing.

--dave

> Peter Dolding
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David Collier-Brown            | Always do right. This will gratify
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