DragonFly kernel List (threaded) for 2009-06
DragonFly BSD
DragonFly kernel List (threaded) for 2009-06
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vproc memory monitoring

From: Pablo Graubner <graubner@xxxxxxxxxxxxxxxxxxxxxxxxx>
Date: Tue, 9 Jun 2009 14:03:43 +0200

Hi folks,

I am working on additional security mechanisms for the dragonfly vkernel and I want to monitor all in-memory copies (like intel asm "mov" and its derivates) of a running vproc in order to check if the vproc is allowed to copy data to the resp. memory segment.

My first approach was to use a technique similar to the implementation used in the emulation of the modified bit in the vkernel: If a vproc request a mapping for a page, the hostkernel disallows writes in the pagetable entry that it instantiates. Afterwards, during handling the resulting pagefault, the permissions of the resp. page should be checked.

I think it is obvious that this approach consumes significantly more time to handle every single memory copy of a vproc as a pagefault. Do you have any idea to monitor in-memory copies without such a performance overhead? As far as I know, there are some Linux binary analysis tools (like "Valgrind") wich could be used for memory- monitoring of a given process. Are there any similar approaches for the dragonfly vkernel which I could use?


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