Re: File access control

From: Stephen Smalley (sds@private)
Date: Mon Dec 01 2003 - 06:02:43 PST

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    On Thu, 2003-11-27 at 13:17, Jonathan Boler wrote:
    > Hi
    > 
    > I'm currently in the planning stage for trying to write a LSM that restricts/allows file access based on the NAME of the file. I hope to be able to specify a set of rules using regular expressions applied to the absolute path of the file to allow/deny lists of users access.
    > 
    > I notice in some of the docs that LSM hooks are called after DAC has taken place but there are cases where you can override this if the call goes through capable(). Is it possible to allow someone access to a file/directory using LSM when the inode permissions deny access ? I'm looking to try and control linking/unlinking, mkdir/rmdir too.
    > 
    > Also is it possible to get the absolute pathname that was used to access an inode so I can restrict access based on the path ?
    > 
    > Any tips would be greatly appreciated.
    
    Pathname-based security considered harmful.  You want to control access
    to an object, not a name, and the name-to-object mapping is neither
    one-to-one nor immutable.
    
    Have you considered whether SELinux will allow you to implement your
    desired security goals via a particular security policy configuration,
    as opposed to implementing a new LSM?
    
    -- 
    Stephen Smalley <sds@private>
    National Security Agency
    



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