[Clamav-devel] CalmAV In-Memory Scan

Michael Engstler michael at cybellum.com
Wed Apr 5 16:23:10 EDT 2017


Hi,
Thanks for the quick response.
Your suggestion sounds interesting, but from what I've seen if you give
clamd a file path, it would copy the file to the temporary directory and
perform its tests on the copied file.
This means that even if i memory map my file, the test would still be done
against the copy file.

Any suggestions how to prevent clamd from copying the file to a temp dir?

Thanks again,
Michael.

On 5 Apr 2017 23:09, "Eugene Crosser" <crosser at average.org> wrote:

On 04/05/2017 09:27 PM, Michael Engstler wrote:
> Hi,
> I noticed that when using the INSTREAM command and sending it a memory
> buffer of a file, clamd takes the memory buffer and saves it to
> the TemporaryDirectory (as defined in the config file).
>
> This is an unnecessary overhead as it requires disk IO in order to scan
the
> file which is already loaded in-memory.
> Is there any way to command clamd to scan the buffer completely in-memory
> without writing anything to the disk?

That's a feature that I requested many years ago because I had a non-copying
MIME parser that worked on mmap()ed files, and I wanted to virus-scan some
parts
of the message. It was not possible, and I think it's not possible now.

I suggest you to mmap() your memory region to a temp. file, ideally on
tmpfs,
and pass this file to clamav. That ought to minimize the overhead.

Eugene


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