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

[Jason King]

Yes.

On Wed, Jan 26, 2011 at 7:20 PM, Garrett D'Amore <garrett at nexenta.com> wrote:
> 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).
>> >
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>>
>>
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