openssl engine pkcs11 signing does not invoke C_CloseAllSessions/C_CloseSession call

[jamyam]

We are using the Utimaco Security server simulator for our secure image signing. During our regression test, we observe that openssl egnine -> pkcs11.so does not invoke the pkcs11 C_CloseAllSessions/C_CloseSession call, causing the server exceed the connection limit. By looking at the libp11 signing code, I do not see C_CloseAllSessions/C_CloseSession call. Please check and confirm this issue.

// A openssl command example:
openssl rand 1024 > ~/fip.bin
openssl dgst -engine pkcs11 -sign "pkcs11:token=CryptoServer PKCS11 Token;object=MCU_SecureImage_SigningKey00;type=private" -keyform engine -sha256 -out ~/fip.bin.sig ~/fip.bin; xxd ~/fip.bin.sig

// pkcs11 log from the server side
03.03.2025 08:53:30.729 | [00353860:00353860] C_FindObjectsInit | T: enter C_FindObjectsInit(hSession: 0x00000001, pTemplate: CK_ATTRIBUTE[2])
03.03.2025 08:53:30.729 | [00353860:00353860] C_FindObjectsInit | T: Attributes in: 2
CKA_CLASS:
CKA_ID:
03.03.2025 08:53:30.729 | [00353860:00353860] C_FindObjectsInit | T: leave C_FindObjectsInit()
03.03.2025 08:53:30.729 | [00353860:00353860] C_FindObjects | T: enter C_FindObjects(hSession: 0x00000001, ulMaxObjectCount: 0x00000001)
03.03.2025 08:53:30.729 | [00353860:00353860] C_FindObjects | T: leave C_FindObjects()
03.03.2025 08:53:30.729 | [00353860:00353860] C_FindObjectsFinal | T: enter C_FindObjectsFinal(hSession: 0x00000001)
03.03.2025 08:53:30.729 | [00353860:00353860] C_FindObjectsFinal | T: leave C_FindObjectsFinal()
03.03.2025 08:53:30.729 | [00353860:00353860] C_GetSessionInfo | T: enter C_GetSessionInfo(hSession: 0x00000001)
03.03.2025 08:53:30.729 | [00353860:00353860] C_GetSessionInfo | T: leave C_GetSessionInfo()
03.03.2025 08:53:30.729 | [00353860:00353860] C_SignInit | T: enter C_SignInit(hSession: 0x00000001, pMechanism: CKM_ECDSA (0x1041), hKey: 0x00000001)
03.03.2025 08:53:30.729 | [00353860:00353860] C_SignInit | T: leave C_SignInit()
03.03.2025 08:53:30.729 | [00353860:00353860] C_Sign | T: enter C_Sign(hSession: 0x00000001)
03.03.2025 08:53:30.730 | [00353860:00353860] C_Sign | T: leave C_Sign()