Re: ima: use of radix tree cache indexing == massive waste of memory?

[Mimi Zohar <zohar@linux.vnet.ibm.com>]

On Sat, 2010-10-16 at 15:20 -0400, Christoph Hellwig wrote:
> Besides the algorithmic problems with ima, why is kernel.org using
> IMA to start with?  Except for IBM looking for a reason to jusity why
> TPM isn't a completely waster of ressources it's pointless.  And it was
> only merged under the premise that it would not affect innocent normal
> users.
> 

Can we keep this at the design level please? When IMA is enabled, it
needs to store information on a per inode basis, yet has to wait to
late_initcall() for the TPM, at which point some inodes would have
already been created.  For this reason, there is a two step
initialization process, one which allocates the iints at
security_initcall() and the other which enables IMA at late_initcall().
Instead of actually allocating the iints, between security_initcall()
and late_initcall(), the original design maintained a list of inodes and
only allocated the iints if/when IMA was enabled. This design was
rejected way back when.

As for using a radix tree, that was what you recommended.

Mimi