Tainting from user space
Posted May 26, 2006 11:56 UTC (Fri) by kravi
In reply to: Tainting from user space
Parent article: Tainting from user space
> If the kernel has granted such access, it should view
> itself as tainted whether or not the user-mode code
> voluntarily flags itself that way.
The kernel doesn't necessarily know that some module is allowing user-space access to physical memory. A module can allocate whatever number of physical pages it wants and allow it to be mmap()ed using a pseudo-device. (BTW, this is what the rmem module in Ted's patch is doing). So it is upto the module to decide whether such access taints the kernel or not.
I think drivers like open-ib (Infiniband) and open-rdma have a legitimate need for such access. So such drivers would not want to taint the kernel.
Note that the patch taints the kernel from within the module. The /proc file is only an additional feature. To quote Ted:
> Technically speaking, we don't need to be able to set it
> via the /proc interface, but it seems like a useful thing
> that could be useful for other applications.
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