xfrm: rate limit SA mapping change message to user space

Kernel generates mapping change message, XFRM_MSG_MAPPING, when a source port chage is detected on a input state with UDP encapsulation set. Kernel generates a message for each IPsec packet with new source port. For a high speed flow per packet mapping change message can be excessive, and can overload the user space listener. Introduce rate limiting for XFRM_MSG_MAPPING message to the user space. The rate limiting is configurable via netlink, when adding a new SA or updating it. Use the new attribute XFRMA_MTIMER_THRESH in seconds. v1->v2 change: update xfrm_sa_len() v2->v3 changes: use u32 insted unsigned long to reduce size of struct xfrm_state fix xfrm_ompat size Reported-by: kernel test robot <lkp@intel.com> accept XFRM_MSG_MAPPING only when XFRMA_ENCAP is present

AAAntony Antony committed 4 years ago