xfrm: configure policy hash table thresholds by netlink

Enable to specify local and remote prefix length thresholds for the policy hash table via a netlink XFRM_MSG_NEWSPDINFO message. prefix length thresholds are specified by XFRMA_SPD_IPV4_HTHRESH and XFRMA_SPD_IPV6_HTHRESH optional attributes (struct xfrmu_spdhthresh). example: struct xfrmu_spdhthresh thresh4 = { .lbits = 0; .rbits = 24; }; struct xfrmu_spdhthresh thresh6 = { .lbits = 0; .rbits = 56; }; struct nlmsghdr *hdr; struct nl_msg *msg; msg = nlmsg_alloc(); hdr = nlmsg_put(msg, NL_AUTO_PORT, NL_AUTO_SEQ, XFRMA_SPD_IPV4_HTHRESH, sizeof(__u32), NLM_F_REQUEST); nla_put(msg, XFRMA_SPD_IPV4_HTHRESH, sizeof(thresh4), &thresh4); nla_put(msg, XFRMA_SPD_IPV6_HTHRESH, sizeof(thresh6), &thresh6); nla_send_auto(sk, msg); The numbers are the policy selector minimum prefix lengths to put a policy in the hash table. - lbits is the local threshold (source address for out policies, destination address for in and fwd policies). - rbits is the remote threshold (destination address for out policies, source address for in and fwd policies). The default values are: XFRMA_SPD_IPV4_HTHRESH: 32 32 XFRMA_SPD_IPV6_HTHRESH: 128 128 Dynamic re-building of the SPD is performed when the thresholds values are changed. The current thresholds can be read via a XFRM_MSG_GETSPDINFO request: the kernel replies to XFRM_MSG_GETSPDINFO requests by an XFRM_MSG_NEWSPDINFO message, with both attributes XFRMA_SPD_IPV4_HTHRESH and XFRMA_SPD_IPV6_HTHRESH.

CGChristophe Gouault committed 12 years ago