Hi,
2020年11月13日(金) 10:57 Dmytro Shytyi <dmy...@shytyi.net>:
>
> Variable SLAAC: SLAAC with prefixes of arbitrary length in PIO (randomly
> generated hostID or stable privacy + privacy extensions).
> The main problem is that SLAAC RA or PD allocates a /64 by the Wireless
> carrier 4G, 5G to a mobile hotspot, however segmentation of the /64 via
> SLAAC is required so that downstream interfaces can be further subnetted.
> Example: uCPE device (4G + WI-FI enabled) receives /64 via Wireless, and
> assigns /72 to VNF-Firewall, /72 to WIFI, /72 to VNF-Router, /72 to
> Load-Balancer and /72 to wired connected devices.
> IETF document that defines problem statement:
> draft-mishra-v6ops-variable-slaac-problem-stmt
> IETF document that specifies variable slaac:
> draft-mishra-6man-variable-slaac
>
> Signed-off-by: Dmytro Shytyi <dmy...@shytyi.net>
> ---
> diff -rupN net-next-5.10.0-rc2/net/ipv6/addrconf.c
> net-next-patch-5.10.0-rc2/net/ipv6/addrconf.c
> --- net-next-5.10.0-rc2/net/ipv6/addrconf.c 2020-11-10 08:46:01.075193379
> +0100
> +++ net-next-patch-5.10.0-rc2/net/ipv6/addrconf.c 2020-11-13
> 02:30:25.552724864 +0100
> @@ -1315,10 +1322,14 @@ static int ipv6_create_tempaddr(struct i
> struct ifa6_config cfg;
> long max_desync_factor;
> struct in6_addr addr;
> - int ret = 0;
> + int ret;
> + struct in6_addr net_mask;
> + struct in6_addr temp;
> + struct in6_addr ipv6addr;
> + int i;
>
> write_lock_bh(&idev->lock);
> -
> + ret = 0;
> retry:
> in6_dev_hold(idev);
> if (idev->cnf.use_tempaddr <= 0) {
> @@ -1340,9 +1351,26 @@ retry:
> goto out;
> }
> in6_ifa_hold(ifp);
> - memcpy(addr.s6_addr, ifp->addr.s6_addr, 8);
> - ipv6_gen_rnd_iid(&addr);
>
> + if (ifp->prefix_len == 64) {
> + memcpy(addr.s6_addr, ifp->addr.s6_addr, 8);
> + ipv6_gen_rnd_iid(&addr);
> + } else if (ifp->prefix_len > 0 && ifp->prefix_len <= 128) {
> + memcpy(addr.s6_addr32, ifp->addr.s6_addr, 16);
> + get_random_bytes(temp.s6_addr32, 16);
> +
> + /* tranfrom prefix len into mask */
> + ipv6_plen_to_mask(ifp->prefix_len, &net_mask);
> +
> + for (i = 0; i < 4; i++) {
> + /* network prefix */
> + ipv6addr.s6_addr32[i] = addr.s6_addr32[i] &
> net_mask.s6_addr32[i];
> + /* host id */
> + ipv6addr.s6_addr32[i] |= temp.s6_addr32[i] &
> ~net_mask.s6_addr32[i];
> + }
> +
> + memcpy(addr.s6_addr, ipv6addr.s6_addr32, 16);
>
ipv6_addr_copy() and then ipv6_addr_prefix_copy()
+ }
> age = (now - ifp->tstamp) / HZ;
>
> regen_advance = idev->cnf.regen_max_retry *
> @@ -2576,9 +2604,57 @@ int addrconf_prefix_rcv_add_addr(struct
> u32 addr_flags, bool sllao, bool tokenized,
> __u32 valid_lft, u32 prefered_lft)
> {
> - struct inet6_ifaddr *ifp = ipv6_get_ifaddr(net, addr, dev, 1);
> + struct inet6_ifaddr *ifp = NULL;
> int create = 0;
>
> + if ((in6_dev->if_flags & IF_RA_VAR_PLEN) == IF_RA_VAR_PLEN &&
> + in6_dev->cnf.addr_gen_mode != IN6_ADDR_GEN_MODE_STABLE_PRIVACY) {
> + struct inet6_ifaddr *result = NULL;
> + struct inet6_ifaddr *result_base = NULL;
> + struct in6_addr net_mask;
> + struct in6_addr net_prfx;
> + struct in6_addr curr_net_prfx;
> + bool prfxs_equal;
> + int i;
> +
> + result_base = result;
> + rcu_read_lock();
> + list_for_each_entry_rcu(ifp, &in6_dev->addr_list, if_list) {
> + if (!net_eq(dev_net(ifp->idev->dev), net))
> + continue;
> +
> + /* tranfrom prefix len into mask */
> + ipv6_plen_to_mask(pinfo->prefix_len, &net_mask);
> + /* Prepare network prefixes */
> + for (i = 0; i < 4; i++) {
> + /* Received/new network prefix */
> + net_prfx.s6_addr32[i] =
> + pinfo->prefix.s6_addr32[i] &
> net_mask.s6_addr32[i];
> + /* Configured/old IPv6 prefix */
> + curr_net_prfx.s6_addr32[i] =
> + ifp->addr.s6_addr32[i] &
> net_mask.s6_addr32[i];
> + }
> + /* Compare network prefixes */
> + prfxs_equal = 1;
> + for (i = 0; i < 4; i++) {
> + if ((net_prfx.s6_addr32[i] ^
> curr_net_prfx.s6_addr32[i]) != 0)
> + prfxs_equal = 0;
> + }
ipv6_prefix_equal()
> + if (prfxs_equal && pinfo->prefix_len ==
> ifp->prefix_len) {
> + result = ifp;
> + in6_ifa_hold(ifp);
> + break;
> + }
> + }
> + rcu_read_unlock();
> + if (result_base != result)
> + ifp = result;
> + else
> + ifp = NULL;
> + } else {
> + ifp = ipv6_get_ifaddr(net, addr, dev, 1);
> + }
> +
> if (!ifp && valid_lft) {
> int max_addresses = in6_dev->cnf.max_addresses;
> struct ifa6_config cfg = {
> @@ -2781,9 +2857,35 @@ void addrconf_prefix_rcv(struct net_devi
> dev_addr_generated = true;
> }
> goto ok;
> + goto put;
> + } else if (((in6_dev->if_flags & IF_RA_VAR_PLEN) ==
> IF_RA_VAR_PLEN) &&
> + pinfo->prefix_len > 0 && pinfo->prefix_len <= 128) {
> + /* SLAAC with prefixes of arbitrary length (Variable
> SLAAC).
> + * draft-mishra-6man-variable-slaac
> + * draft-mishra-v6ops-variable-slaac-problem-stmt
> + * Contact: Dmytro Shytyi.
> + */
> + memcpy(&addr, &pinfo->prefix, 16);
> + if (in6_dev->cnf.addr_gen_mode ==
> IN6_ADDR_GEN_MODE_STABLE_PRIVACY) {
> + if
> (!ipv6_generate_address_variable_plen(&addr,
> + 0,
> +
> in6_dev,
> +
> pinfo->prefix_len,
> +
> true)) {
> + addr_flags |= IFA_F_STABLE_PRIVACY;
> + goto ok;
> + }
> + } else if (!ipv6_generate_address_variable_plen(&addr,
> + 0,
> +
> in6_dev,
> +
> pinfo->prefix_len,
> +
> false)) {
> + goto ok;
> + }
> + } else {
> + net_dbg_ratelimited("IPv6: Prefix with unexpected
> length %d\n",
> + pinfo->prefix_len);
> }
> - net_dbg_ratelimited("IPv6 addrconf: prefix with wrong length
> %d\n",
> - pinfo->prefix_len);
> goto put;
>
> ok:
> @@ -3264,6 +3366,118 @@ retry:
> return 0;
> }
>
> +static void ipv6_plen_to_mask(int plen, struct in6_addr *net_mask)
> +{
> + int i, plen_bytes;
> + char bit_array[7] = {0b10000000,
> + 0b11000000,
> + 0b11100000,
> + 0b11110000,
> + 0b11111000,
> + 0b11111100,
> + 0b11111110};
> +
> + if (plen <= 0 || plen > 128)
> + pr_err("Unexpected plen: %d", plen);
> +
> + memset(net_mask, 0x00, sizeof(*net_mask));
> +
> + /* We set all bits == 1 of s6_addr[i] */
> + plen_bytes = plen / 8;
> + for (i = 0; i < plen_bytes; i++)
> + net_mask->s6_addr[i] = 0xff;
> +
> + /* We add bits from the bit_array to
> + * netmask starting from plen_bytes position
> + */
> + if (plen % 8)
> + net_mask->s6_addr[plen_bytes] = bit_array[(plen % 8) - 1];
> + memcpy(net_mask->s6_addr32, net_mask->s6_addr, 16);
> +}
I don't think we need this function.
If needed, we could introduce ipv6_addr_host() (like ipv6_addr_prefix())
in include/net/ipv6.h.
