Finer granularity user plane security policy configuration

1. A non-transitory computer-readable storage medium, the non-transitory computer-readable storage medium including instructions that when executed by a processor of a base station, cause the processor to:

perform a protocol data unit (PDU) session establishment procedure with a user equipment (UE) and a core network of a wireless communication system;

process, in the PDU session establishment procedure, a user plane (UP) security policy from a network function of the core network to determine a granularity level of the UP security policy;

generate a radio resource configuration (RRC) connection reconfiguration message, for the UE, comprising a UP integrity and ciphering indication configured based on the granularity level of the UP security policy; and

apply security protection to a subset UP traffic with the UE according to the UP security policy.

2. The non-transitory computer-readable storage medium of claim 1 , wherein a portion of the UP traffic is communicated without the security protection based at least in part on the granularity level of the UP security policy.

3. The non-transitory computer-readable storage medium of claim 1 , wherein to determine the granularity level of the UP security policy comprises to determine that the UP security policy from the network function is per PDU session, per data radio bearer (DRB) within the PDU session, or per quality of service (QoS) flow within one or more DRB of the PDU session.

4. The non-transitory computer-readable storage medium of claim 3 , wherein the instructions further configure the processor to configure a DRB level UP security policy for the UE.

5. The non-transitory computer-readable storage medium of claim 4 , wherein the instructions further configure the processor to, when the UP security policy from the network function is per PDU session, configure the UP integrity and ciphering indication for each of the one or more DRB of the PDU session.

6. The non-transitory computer-readable storage medium of claim 4 , wherein the instructions further configure the processor to, when the UP security policy from the network function is per DRB within the PDU session, configure a first DRB with a first UP integrity and ciphering indication and a second DRB with a second UP integrity and ciphering indication.

7. The non-transitory computer-readable storage medium of claim 4 , wherein the instructions further configure the processor to, when the UP security policy from the network function is per QoS flow:

map each QoS flow to the one or more DRB of the PDU session; and

configure a first DRB with a first UP integrity and ciphering indication and a second DRB with a second UP integrity and ciphering indication.

8. The non-transitory computer-readable storage medium of claim 7 , wherein the instructions further configure the processor to determine, from the UP security policy from the network function, a respective UP security policy for each of the one or more DRB of the PDU session.

9. The non-transitory computer-readable storage medium of claim 3 , wherein the instructions further configure the processor to configure a QoS flow level UP security policy for the UE.

10. The non-transitory computer-readable storage medium of claim 9 , wherein the instructions further configure the processor to, when the UP security policy from the network function is per PDU session:

redefine the granularity level of the UP security policy from the per PDU session to the QoS flow level; and

configure the UP integrity and ciphering indication for each QoS flow of the PDU session.

11. The non-transitory computer-readable storage medium of claim 9 , wherein the instructions further configure the processor to, when the UP security policy from the network function is per DRB within the PDU session:

map each of the one or more DRB to the QoS flow level UP security policy; and

configure a first QoS flow with a first UP integrity and ciphering indication and a second QoS flow with a second UP integrity and ciphering indication.

12. The non-transitory computer-readable storage medium of claim 11 , wherein the instructions further configure the processor to determine, from the UP security policy from the network function, a respective UP security policy for each QoS flow from the per DRB UP security policy from the network function.

13. The non-transitory computer-readable storage medium of claim 9 , wherein the instructions further configure the processor to, when the UP security policy from the network function is per QoS flow, configure a first QoS flow with a first UP integrity and ciphering indication and a second QoS flow with a second UP integrity and ciphering indication.

14. The non-transitory computer-readable storage medium of claim 1 , wherein to process the UP security policy from the network function comprises to process the UP security policy from a session management function (SMF) of the core network.

15. A method for a session management function (SMF) of a core network in a wireless communication system, the method comprising:

in a protocol data unit (PDU) session establishment procedure, processing session management subscription data for a corresponding user equipment (UE), the session management subscription data including a user plane (UP) security policy for a PDU session of the UE;

based at least in part on a maximum data rate of the UE for integrity protected traffic, determining a granularity for applying the UP security policy to the UE; and

generating UP security enforcement information to send to an access and mobility management function (AMF) to communicate the UP security policy to a radio access network (RAN) node connected to the UE, the UP security policy indicating the granularity for the RAN node to configure the UP security policy to the UE.

16. The method of claim 15 , wherein the granularity for applying the UP security policy to the UE is selected from a group comprising per PDU session, per data radio bearer (DRB) within the PDU session, or per quality of service (QoS) flow within one or more DRB of the PDU session.

17. The method of claim 16 , wherein for the granularity per QoS flow, the UP security policy indicates that different QoS flows have different UP security policies.

18. The method of claim 17 , wherein the UP security policy is part of one or more QoS rules or QoS profiles for the UE.

19. The method of claim 16 , wherein for the granularity per DRB, the UP security policy indicates that different DRBs within the PDU session have different UP security policies.

20. A method for a user equipment (UE), comprising:

in a protocol data unit (PDU) session establishment procedure, processing a radio resource configuration (RRC) connection reconfiguration message from a radio access network (RAN) node, the RRC connection reconfiguration message including a user plane (UP) security policy comprising a granularity level for applying security protection to UP traffic between the UE and the RAN node, the granularity level based at least in part on the UE integrity protection maximum data rate; and

applying the security protection to a subset of the UP traffic with the RAN node according to the UP security policy.