Parsing Structures postmortem from memory dump

Parsing Structures postmortem from memory dump

[Adrian Sud]

Hi,

I am working on a project attempting to extend the volatility toolkit 
(www.volatilesystems.com) to read Linux memory; for now I am attempting 
to support Kernel 2.6.22-14 using i686 arch.

What I mean to do is have it first identify that the image is from a 
linux environment, and then parse out the processes that were running 
when the image was taken.

I've looked at /include/linux/sched.h and tried to understand the 
task_struct structure, but it appears to be variable-length, determined 
at compile time, and I can't tell exactly how these are stored 
throughout memory--In a list? a tree?

If anyone can point me to more information toward finding out how to 
trace this, I would appreciate it.

Thank you,

Adrian Sud

UMass Amherst
Dept. of Computer Science

Re: Parsing Structures postmortem from memory dump

[Dan Noé]

Adrian Sud wrote:
> I've looked at /include/linux/sched.h and tried to understand the 
> task_struct structure, but it appears to be variable-length, determined 
> at compile time, and I can't tell exactly how these are stored 
> throughout memory--In a list? a tree?

The task_struct structures are stored on one or more lists.  Note the 
list_head types within the structure - each of this is a list that the 
structure is (potentially) a member of.

This is a good explanation of how the kernel's lists work:

http://kernelnewbies.org/FAQ/LinkedLists

I don't know if a generalized printer/parser exists for the kernel 
linked list, but this might be a good way to start exploring your 
project.  There are macros to traverse the lists easily, so it shouldn't 
be too difficult.

Hope that helps.

Cheers,
Dan

-- 
                     /--------------- - -  -  -   -   -
                     |  Dan Noé
                     |  http://isomerica.net/~dpn/