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SubjectRe: [PATCH v6 6/7] crypto: caam - enable prediction resistance in HRWNG
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On 1/20/2020 6:38 PM, Horia Geanta wrote:
> On 1/8/2020 5:42 PM, Andrey Smirnov wrote:
>> @@ -275,12 +276,25 @@ static int instantiate_rng(struct device *ctrldev, int state_handle_mask,
>> return -ENOMEM;
>>
>> for (sh_idx = 0; sh_idx < RNG4_MAX_HANDLES; sh_idx++) {
>> + const u32 rdsta_if = RDSTA_IF0 << sh_idx;
>> + const u32 rdsta_pr = RDSTA_PR0 << sh_idx;
>> + const u32 rdsta_mask = rdsta_if | rdsta_pr;
>> /*
>> * If the corresponding bit is set, this state handle
>> * was initialized by somebody else, so it's left alone.
>> */
>> - if ((1 << sh_idx) & state_handle_mask)
>> - continue;
>> + if (rdsta_if & state_handle_mask) {
>> + if (rdsta_pr & state_handle_mask)
>> + continue;
>> +
>> + dev_info(ctrldev,
>> + "RNG4 SH%d was previously instantiated without prediction resistance. Tearing it down\n",
>> + sh_idx);
>> +
>> + ret = deinstantiate_rng(ctrldev, rdsta_if);
>> + if (ret)
>> + break;
> In case state handle 0 is deinstantiated, its reinstantiation with PR support
> will have the side effect of re-generating JDKEK, TDKEK, TDSK.
> This needs to be avoided, since other SW components (like OP-TEE f/w)
> could have black keys in use. Overwriting the KEK registers would no longer
> allow CAAM to decrypt them.
>
Never mind, looks like there is logic in place to check whether
keys have been generated or not, by looking at RDSTA[SKVN].

Horia

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