Re: [patch 0/5] Support for sanitization flag in low-level page allocator

Pavel Machek
2009-05-28T12:48:03Z

Hi!

> Index: linux-2.6/mm/Kconfig
> ===================================================================
> --- linux-2.6.orig/mm/Kconfig
> +++ linux-2.6/mm/Kconfig
> @@ -155,6 +155,26 @@ config PAGEFLAGS_EXTENDED
> def_bool y
> depends on 64BIT || SPARSEMEM_VMEMMAP || !NUMA || !SPARSEMEM
>
> +config PAGE_SENSITIVE
> + bool "Support for selective page sanitization"
> + help
> + This option provides support for honoring the sensitive bit
> + in the low level page allocator. This bit is used to mark
> + pages that will contain sensitive information (such as
> + cryptographic secrets and credentials).
> +
> + Pages marked with the sensitive bit will be sanitized upon
> + release, to prevent information leaks and data remanence that
> + could allow Iceman/coldboot attacks to reveal such data.
> +
> + If you are unsure, select N. This option might introduce a
> + minimal performance impact on those subsystems that make
> + use of the flag associated with the sensitive bit.
> +
> + If you use the cryptographic API or want to prevent tty
> + information leaks locally, you most likely want to enable
> + this.

This should not be configurable. Runtime config, defaulting to
'sanitize' may make some sense, but... better just be secure.

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