Messages in this thread | | | Subject | Re: [PATCH Part1 v5 34/38] x86/sev: Add snp_msg_seqno() helper | From | Brijesh Singh <> | Date | Thu, 9 Sep 2021 11:17:10 -0500 |
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On 9/9/21 10:43 AM, Peter Gonda wrote: ...
>> >> Does this address your concern? > > So the 'snp_msg_seqno()' call in 'enc_payload' will not increment the > counter, its only incremented on 'snp_gen_msg_seqno()'? If thats > correct, that addresses my first concern. >
Yes, that is goal.
>>> >> >> So far, the only user for the snp_msg_seqno() is the attestation driver. >> And the driver is designed to serialize the vmgexit request and thus we >> should not run into concurrence issue. > > That seems a little dangerous as any module new code or out-of-tree > module could use this function thus revealing this race condition > right? Could we at least have a comment on these functions > (snp_msg_seqno and snp_gen_msg_seqno) noting this? >
Yes, if the driver is not performing the serialization then we will get into race condition.
One way to avoid this requirement is to do all the crypto inside the snp_issue_guest_request() and eliminate the need to export the snp_msg_seqno().
I will add the comment about it in the function.
thanks
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