tls key lookup matches too eagerly?

[Hannes Reinecke]

On 10/24/24 10:20, Daniel Wagner wrote:
> Hi Hannes,
> 
> While testing my TLS handling changes in nvme-cli/libnvme, I found out
> that it is possible to insert a key with a identity of "NVMe1R01" only
> and the kernel was happy to use this key.
> 
> nvme_tls_psk_lookup
>    keyring_search
>    	struct keyring_search_context ctx = {
> 		.index_key.description	= description,
> 		.index_key.desc_len	= strlen(description),
>          	.match_data.cmp		= key_default_cmp,
>                  [...]
>          }
> 
> /*
>   * By default, we keys found by getting an exact match on their descriptions.
>   */
> bool key_default_cmp(const struct key *key,
> 		     const struct key_match_data *match_data)
> {
> 	return strcmp(key->description, match_data->raw_data) == 0;
> }
> 
> I think we should at least enforce that the identity set by user space
> fullfills the required format. Does this make sense?
> 
That is actually correct; we need to extend the match to ensure that
there is _something_ after the NVMe1R01 prefix.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                  Kernel Storage Architect
hare at suse.de                                +49 911 74053 688
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