cipso_ipv4.rst 2.3 KB

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  1. ===================================
  2. NetLabel CIPSO/IPv4 Protocol Engine
  3. ===================================
  4. Paul Moore, paul.moore@hp.com
  5. May 17, 2006
  6. Overview
  7. ========
  8. The NetLabel CIPSO/IPv4 protocol engine is based on the IETF Commercial
  9. IP Security Option (CIPSO) draft from July 16, 1992. A copy of this
  10. draft can be found in this directory
  11. (draft-ietf-cipso-ipsecurity-01.txt). While the IETF draft never made
  12. it to an RFC standard it has become a de-facto standard for labeled
  13. networking and is used in many trusted operating systems.
  14. Outbound Packet Processing
  15. ==========================
  16. The CIPSO/IPv4 protocol engine applies the CIPSO IP option to packets by
  17. adding the CIPSO label to the socket. This causes all packets leaving the
  18. system through the socket to have the CIPSO IP option applied. The socket's
  19. CIPSO label can be changed at any point in time, however, it is recommended
  20. that it is set upon the socket's creation. The LSM can set the socket's CIPSO
  21. label by using the NetLabel security module API; if the NetLabel "domain" is
  22. configured to use CIPSO for packet labeling then a CIPSO IP option will be
  23. generated and attached to the socket.
  24. Inbound Packet Processing
  25. =========================
  26. The CIPSO/IPv4 protocol engine validates every CIPSO IP option it finds at the
  27. IP layer without any special handling required by the LSM. However, in order
  28. to decode and translate the CIPSO label on the packet the LSM must use the
  29. NetLabel security module API to extract the security attributes of the packet.
  30. This is typically done at the socket layer using the 'socket_sock_rcv_skb()'
  31. LSM hook.
  32. Label Translation
  33. =================
  34. The CIPSO/IPv4 protocol engine contains a mechanism to translate CIPSO security
  35. attributes such as sensitivity level and category to values which are
  36. appropriate for the host. These mappings are defined as part of a CIPSO
  37. Domain Of Interpretation (DOI) definition and are configured through the
  38. NetLabel user space communication layer. Each DOI definition can have a
  39. different security attribute mapping table.
  40. Label Translation Cache
  41. =======================
  42. The NetLabel system provides a framework for caching security attribute
  43. mappings from the network labels to the corresponding LSM identifiers. The
  44. CIPSO/IPv4 protocol engine supports this caching mechanism.