Re: [Patch] allow file truncations when both suid and write permissionsset

[Amerigo Wang]

Eric Paris wrote:
> On Thu, 2009-07-02 at 18:14 +0800, Amerigo Wang wrote:
>   
> > Eric Paris wrote:
> >     
> > > So NAK on both Amerigo's and Eric's patch.  ATTR_FORCE is wrong.
> > > ATTR_FORCE here is going to force the security system to accept ALL of
> > > the attr changes, not just the ATTR_KILL_SUID and/or ATTR_KILL_SGID you
> > > |= in from should_remove_suid.
> > > You need to follow esandeen's recommendation, change file_remove_suid()
> > > to dentry_remove_suid() and then use dentry_remove_suid() in do_truncate
> > > instead of what you are currently trying to do (and I think that's
> > > supposed to be done under the i_mutex right?)
> > >   
> > >       
> > But file_remove_suid() actually adds ATTR_FORCE too, in __remove_suid()...
> >     
>
> The difference being that it adds it to a private ia_valid that ONLY
> contains the SUID/SGID bits that we need to force the removal of.  Not
> to the ia_valid that contains ATTR_SIZE and ATTR_FILE.
>   

Yeah! Got it. I will prepare a new patch...

Thank you!

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