Re: [RFC][PATCH 11/11] security: AppArmor - Export namespace semaphore

[Christoph Hellwig]

On Wed, Apr 19, 2006 at 10:50:34AM -0700, Tony Jones wrote:
> This patch exports the namespace_sem semaphore.
> 
> The shared subtree patches which went into 2.6.15-rc1 replaced the old
> namespace semaphore which used to be per namespace (and visible) with a
> new single static semaphore.
> 
> The reason for this change is that currently visibility of vfsmount information
> to the LSM hooks is fairly patchy.  Either there is no passed parameter or
> it can be NULL.  For the case of the former,  several LSM hooks that we
> require to mediate have no vfsmount/nameidata passed.  We previously (mis)used
> the visibility of the old per namespace semaphore to walk the processes 
> namespace looking for vfsmounts with a root dentry matching the dentry we were 
> trying to mediate.  
> 
> Clearly this is not viable long term strategy and changes working towards 
> passing a vfsmount to all relevant LSM hooks would seem necessary (and also 
> useful for other users of LSM). Alternative suggestions and ideas are welcomed.

Just don't do it.  No module has any business looking in there, and no
non-modular code outside a few files in fs/ either.
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