[Cbe-oss-dev] 64k pages vs. problem state register mappings

[Benjamin Herrenschmidt]

On Wed, 2006-06-07 at 01:27 +0200, Arnd Bergmann wrote:

> For 2., the first three files are already protected with CAP_SYS_RAWIO,
> so they are normally only mappable with root priviledges. For the two
> signal notification registers, doing the mmap on one of them also
> gives a pointer to the other. This is potentially harmful if one 
> of the two registers is used for communication with a process owned
> by a different user, a model that libspe currently doesn't provide.
> I guess the best we can do here is document it in the libspe man page
> and warn users about potential security risks there.

And provide a syscall or sysfs interface to access these things without
mmap'ing them so that fine grained protection can be kept with 64k pages
at the expense of some performances.

Ben.