Messages in this thread | | | Subject | Re: access_ok inside kernelspace | Date | Tue, 19 Oct 1999 12:27:55 -0300 | From | Horst von Brand <> |
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Tigran Aivazian <tigran@sco.COM> said: > On Tue, 19 Oct 1999, Horst von Brand wrote: > > I don't understand this. A module is linked into the running kernel, and > > has access to all of it AFAIU, so I can't see any need for this contortion > > for modules. Maybe I'm just plain blind today...
> The kernel only has access to symbols which base kernel chose to export > (kernel/ksyms.c and arch/i386/kernel/i386_ksyms.c). However, you are not > blind and neither was I - just slightly short-sighted :)
But you can export them if you wish. Is there anything against that idea?
> I forgot about the well-known fact that sys_call_table[] is exported so > modules should call sys_XXX() functions indirectly via sys_call_table[].
That means an array lookup + a indirect function call, and also no argument checking by gcc. Not exactly a overwhelming cost, but...
> I even wrote a little module ages ago that is based solely on this simple > fact.
;-) -- Dr. Horst H. von Brand mailto:vonbrand@inf.utfsm.cl Departamento de Informatica Fono: +56 32 654431 Universidad Tecnica Federico Santa Maria +56 32 654239 Casilla 110-V, Valparaiso, Chile Fax: +56 32 797513
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