LSM patch for Linux-2.4.20-8

From: Syed Ahemed (kingkhan@private)
Date: Mon Jan 17 2005 - 10:15:56 PST


Hi 
I have a few questions regarding LSM implementation.
I hope i dont drive the mailing list crazy with my ignorance , but i
have given it my best shot reading it already .

Issue 1
-----------
Have been trying to understand the need for LSM from the security perspective .
As per my understanding  the patch employes LSM framework
by adding a hook to the source just before a system resources is
accessed .The hook inturns calls the policy engine (ideally the hook
is a call to a function ) .

1] Does the patch include the source for  policy engine? 
        If yes how do i set rules to access a file ?
        If no do i have to implement the policy engine ?
For instance open() system call without the LSM patch checks for file
attributes for read write permissions from the user .
What does this   "security_ops->file_permission (file, MAY_WRITE); "
do additionally?

In short do i need to write  "C code" to implement the security
solution like checking if a file has symbolic link before opening to
avoid race condition ?

Issue 2
-----------
Apart from modular implementation the reason i moved from LIDS patch
without LSM --> LSM with OPENWALL/LIDS/SELINUX was because
LIDS provides administrative control over files and process and not
kernel level security . LIDS doesnt guarantee bufferover flow
solution. Openwall/LSM does

2] Does LSM with all its security modules(Open wall , LIDS, SELINUX 
)co-exist and IMPLEMENT  a solution to buffer overflow , format
strings and race conditions ?

What are the vulnerabilities that would remain if I dont use LIDS? 


Thanks
Syed Ahemed



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