[illumos-Developer] Proposal: Add memory clearing allocator to libnvpair

[Garrett D'Amore]

Jason, I missed your original message.

That said, this sounds like an easy improvement.  I presume we are only
talking about doing this for userland, and not for kernel space?

The reference passed into nvlist_xalloc is used to receive the pointer
to the newly allocated structure.  Its done this way so that
nvlist_alloc() and return different errnos on success.

	- Garrett

On Wed, 2011-01-26 at 14:52 -1000, Samuel Younge wrote:
> It seems a bit troubling that nvlist_xalloc is accepting nvl as a reference rather than a value, but I cannot access my code base at the moment to be sure of this. What are your thoughts? Although, I like your intention of not leaving passwords pins key etc. hanging about.
> 
> 
> 
> On Jan 26, 2011, at 13:42, Jason King <jason.brian.king at gmail.com> wrote:
> 
> > Something that's hopefully minor and not controversial.  I was
> > planning to do this for the work I'm doing with the IKEv2 support, but
> > figured it's probably generally enough useful to live outside of it.
> > 
> > The libnvpair library (userland) normally uses the malloc/free
> > commands for its memory requirements.  It also specifies a pluggable
> > allocator interface for use with the nvlist_xalloc(3nvpair) and
> > nvlist_xdup(3nvpair) function.  I would like to propose to add to
> > libnvpair an allocator that zeros out the memory when allocated and
> > freed.  This would be useful in situations where nvlists may contain
> > sensitive information such as passwords/pins/keys/etc.
> > 
> > Specifically, add to libnvpair.h
> > 
> > extern nv_alloc_t *nv_alloc_zero;
> > 
> > Programs can then use (return codes elided for clarity):
> > 
> > nvlist_t *nvl;
> > int flags = ...; /* NV_UNIQUE_NAME, NV_UNIQUE_NAME_TYPE or 0 */
> > 
> > nvlist_xalloc(&nvl, flags, nv_alloc_zero);
> > ...
> > add/remove data from nvlist
> > ...
> > nvlist_free(nvl);
> > 
> > And the memory used will be zeroed out before being returned to the
> > system via free(3c).
> > 
> > _______________________________________________
> > Developer mailing list
> > Developer at lists.illumos.org
> > http://lists.illumos.org/m/listinfo/developer
> 
> 
> 
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