ykcs11: session cap is global, not per-slot #573
Description
ykcs11 globally limits the session count to 16:
yubico-piv-tool/ykcs11/ykcs11.c
Line 57 in 7851acf
... and reports the same value in CK_TOKEN_INFO's ulMaxSessionCount & ulMaxRwSessionCount.
However, as per PKCS#11 standard, these values should represent the per-token limit, not a global limit:
ulMaxSessionCount maximum number of sessions that can be opened with the token at one time by a single application
As a result, applications that consume PKCS#11 modules generically are led to assume that they can open up to 16 concurrent sessions per token slot, which is not actually guaranteed, and will lead to unexpected errors.
Am I interpreting this incorrectly? What are the odds this can be patched to track sessions per-slot? I realize this may not be a straightforward refactor given session memory is currently statically allocated, which is likely impractical going forward if done per-slot.