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 2020-11-19
12:27:58.252392820 +0100
@@ -142,7 +142,6 @@ static int ipv6_count_addresses(const st
static int ipv6_generate_stable_address(struct in6_addr *addr,
u8 dad_count,
const struct inet6_dev *idev);
-
#define IN6_ADDR_HSIZE_SHIFT 8
#define IN6_ADDR_HSIZE (1 << IN6_ADDR_HSIZE_SHIFT)
/*
@@ -1315,6 +1314,7 @@ static int ipv6_create_tempaddr(struct i
struct ifa6_config cfg;
long max_desync_factor;
struct in6_addr addr;
+ struct in6_addr temp;
int ret = 0;
write_lock_bh(&idev->lock);
@@ -1340,9 +1340,16 @@ 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);
+ ipv6_addr_prefix_copy(&temp, &addr, ifp->prefix_len);
+ memcpy(addr.s6_addr, temp.s6_addr, 16);
+ }
age = (now - ifp->tstamp) / HZ;
regen_advance = idev->cnf.regen_max_retry *
@@ -2569,6 +2576,41 @@ static bool is_addr_mode_generate_stable
idev->cnf.addr_gen_mode == IN6_ADDR_GEN_MODE_RANDOM;
}
+struct inet6_ifaddr *ipv6_cmp_rcvd_prsnt_prfxs(struct inet6_ifaddr *ifp,
+ struct inet6_dev *in6_dev,
+ struct net *net,
+ const struct prefix_info *pinfo)
+{
+ struct inet6_ifaddr *result_base = NULL;
+ struct inet6_ifaddr *result = NULL;
+ struct in6_addr curr_net_prfx;
+ struct in6_addr net_prfx;
+ bool prfxs_equal;
+
+ 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;
+ ipv6_addr_prefix_copy(&net_prfx, &pinfo->prefix,
pinfo->prefix_len);
+ ipv6_addr_prefix_copy(&curr_net_prfx, &ifp->addr,
pinfo->prefix_len);
+ prfxs_equal =
+ ipv6_prefix_equal(&net_prfx, &curr_net_prfx,
pinfo->prefix_len);
+ 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;
+
+ return ifp;
+}
+
int addrconf_prefix_rcv_add_addr(struct net *net, struct net_device *dev,
const struct prefix_info *pinfo,
struct inet6_dev *in6_dev,
@@ -2576,9 +2618,17 @@ 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 plen = pinfo->prefix_len;
int create = 0;
+ if (plen > 0 && plen <= 128 && plen != 64 &&
+ in6_dev->cnf.addr_gen_mode != IN6_ADDR_GEN_MODE_STABLE_PRIVACY) {
+ ifp = ipv6_cmp_rcvd_prsnt_prfxs(ifp, in6_dev, net, pinfo);
+ } else if (plen == 64) {
+ ifp = ipv6_get_ifaddr(net, addr, dev, 1);
+ }
+
if (!ifp && valid_lft) {
int max_addresses = in6_dev->cnf.max_addresses;
struct ifa6_config cfg = {
@@ -2657,6 +2707,91 @@ int addrconf_prefix_rcv_add_addr(struct
}
EXPORT_SYMBOL_GPL(addrconf_prefix_rcv_add_addr);
+static bool ipv6_reserved_interfaceid(struct in6_addr address)
+{
+ if ((address.s6_addr32[2] | address.s6_addr32[3]) == 0)
+ return true;
+
+ if (address.s6_addr32[2] == htonl(0x02005eff) &&
+ ((address.s6_addr32[3] & htonl(0xfe000000)) == htonl(0xfe000000)))
+ return true;
+
+ if (address.s6_addr32[2] == htonl(0xfdffffff) &&
+ ((address.s6_addr32[3] & htonl(0xffffff80)) == htonl(0xffffff80)))
+ return true;
+
+ return false;
+}
+
+static int ipv6_gen_addr_var_plen(struct in6_addr *address,
+ u8 dad_count,
+ const struct inet6_dev *idev,
+ unsigned int rcvd_prfx_len,
+ bool stable_privacy_mode)
+{
+ static union {
+ char __data[SHA1_BLOCK_SIZE];
+ struct {
+ struct in6_addr secret;
+ __be32 prefix[2];
+ unsigned char hwaddr[MAX_ADDR_LEN];
+ u8 dad_count;
+ } __packed;
+ } data;
+ static __u32 workspace[SHA1_WORKSPACE_WORDS];
+ static __u32 digest[SHA1_DIGEST_WORDS];
+ struct net *net = dev_net(idev->dev);
+ static DEFINE_SPINLOCK(lock);
+ struct in6_addr secret;
+ struct in6_addr temp;
+
+ BUILD_BUG_ON(sizeof(data.__data) != sizeof(data));
+
+ if (stable_privacy_mode) {
+ if (idev->cnf.stable_secret.initialized)
+ secret = idev->cnf.stable_secret.secret;
+ else if (net->ipv6.devconf_dflt->stable_secret.initialized)
+ secret = net->ipv6.devconf_dflt->stable_secret.secret;
+ else
+ return -1;
+ }
+
+retry:
+ spin_lock_bh(&lock);
+ if (stable_privacy_mode) {
+ sha1_init(digest);
+ memset(&data, 0, sizeof(data));
+ memset(workspace, 0, sizeof(workspace));
+ memcpy(data.hwaddr, idev->dev->perm_addr, idev->dev->addr_len);
+ data.prefix[0] = address->s6_addr32[0];
+ data.prefix[1] = address->s6_addr32[1];
+ data.secret = secret;
+ data.dad_count = dad_count;
+
+ sha1_transform(digest, data.__data, workspace);
+
+ temp = *address;
+ temp.s6_addr32[0] = (__force __be32)digest[0];
+ temp.s6_addr32[1] = (__force __be32)digest[1];
+ temp.s6_addr32[2] = (__force __be32)digest[2];
+ temp.s6_addr32[3] = (__force __be32)digest[3];
+ } else {
+ temp = *address;
+ get_random_bytes(temp.s6_addr32, 16);
+ }
+ spin_unlock_bh(&lock);
+
+ if (ipv6_reserved_interfaceid(temp)) {
+ dad_count++;
+ if (dad_count > dev_net(idev->dev)->ipv6.sysctl.idgen_retries)
+ return -1;
+ goto retry;
+ }
+ ipv6_addr_prefix_copy(&temp, address, rcvd_prfx_len);
+ *address = temp;
+ return 0;
+}
+
void addrconf_prefix_rcv(struct net_device *dev, u8 *opt, int len, bool sllao)
{
struct prefix_info *pinfo;
@@ -2781,9 +2916,33 @@ void addrconf_prefix_rcv(struct net_devi
dev_addr_generated = true;
}
goto ok;
+ } else if (pinfo->prefix_len != 64 &&
+ 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
+ */
+ memcpy(&addr, &pinfo->prefix, 16);
+ if (in6_dev->cnf.addr_gen_mode ==
IN6_ADDR_GEN_MODE_STABLE_PRIVACY) {
+ if (!ipv6_gen_addr_var_plen(&addr,
+ 0,
+ in6_dev,
+ pinfo->prefix_len,
+ true)) {
+ addr_flags |= IFA_F_STABLE_PRIVACY;
+ goto ok;
+ }
+ } else if (!ipv6_gen_addr_var_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:
@@ -3186,22 +3345,6 @@ void addrconf_add_linklocal(struct inet6
}
EXPORT_SYMBOL_GPL(addrconf_add_linklocal);
-static bool ipv6_reserved_interfaceid(struct in6_addr address)
-{
- if ((address.s6_addr32[2] | address.s6_addr32[3]) == 0)
- return true;
-
- if (address.s6_addr32[2] == htonl(0x02005eff) &&
- ((address.s6_addr32[3] & htonl(0xfe000000)) == htonl(0xfe000000)))
- return true;
-
- if (address.s6_addr32[2] == htonl(0xfdffffff) &&
- ((address.s6_addr32[3] & htonl(0xffffff80)) == htonl(0xffffff80)))
- return true;
-
- return false;
-}
-
static int ipv6_generate_stable_address(struct in6_addr *address,
u8 dad_count,
const struct inet6_dev *idev)
