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/include/net/if_inet6.h
net-next-patch-5.10.0-rc2/include/net/if_inet6.h
--- net-next-5.10.0-rc2/include/net/if_inet6.h 2020-11-10 08:46:00.195180579
+0100
+++ net-next-patch-5.10.0-rc2/include/net/if_inet6.h 2020-11-11
18:11:05.627550135 +0100
@@ -22,6 +22,12 @@
#define IF_RS_SENT 0x10
#define IF_READY 0x80000000
+/* Variable SLAAC (Contact: Dmytro Shytyi)
+ * draft-mishra-6man-variable-slaac
+ * draft-mishra-v6ops-variable-slaac-problem-stmt
+ */
+#define IF_RA_VAR_PLEN 0x08
+
/* prefix flags */
#define IF_PREFIX_ONLINK 0x01
#define IF_PREFIX_AUTOCONF 0x02
diff -rupN net-next-5.10.0-rc2/include/uapi/linux/icmpv6.h
net-next-patch-5.10.0-rc2/include/uapi/linux/icmpv6.h
--- net-next-5.10.0-rc2/include/uapi/linux/icmpv6.h 2020-11-10
08:46:00.351849525 +0100
+++ net-next-patch-5.10.0-rc2/include/uapi/linux/icmpv6.h 2020-11-11
18:11:05.627550135 +0100
@@ -42,7 +42,9 @@ struct icmp6hdr {
struct icmpv6_nd_ra {
__u8 hop_limit;
#if defined(__LITTLE_ENDIAN_BITFIELD)
- __u8 reserved:3,
+ __u8 reserved:1,
+ slaac_var_plen:1,
+ proxy:1,
router_pref:2,
home_agent:1,
other:1,
@@ -53,7 +55,9 @@ struct icmp6hdr {
other:1,
home_agent:1,
router_pref:2,
- reserved:3;
+ proxy:1,
+ slaac_var_plen:1,
+ reserved:1;
#else
#error "Please fix <asm/byteorder.h>"
#endif
@@ -78,9 +82,9 @@ struct icmp6hdr {
#define icmp6_addrconf_other icmp6_dataun.u_nd_ra.other
#define icmp6_rt_lifetime icmp6_dataun.u_nd_ra.rt_lifetime
#define icmp6_router_pref icmp6_dataun.u_nd_ra.router_pref
+#define icmp6_slaac_var_plen icmp6_dataun.u_nd_ra.slaac_var_plen
};
-
#define ICMPV6_ROUTER_PREF_LOW 0x3
#define ICMPV6_ROUTER_PREF_MEDIUM 0x0
#define ICMPV6_ROUTER_PREF_HIGH 0x1
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
@@ -11,6 +11,8 @@
/*
* Changes:
*
+ * Dmytro Shytyi : Variable SLAAC: SLAAC with
+ * <dmy...@shytyi.net> prefixes of arbitrary length.
* Janos Farkas : delete timer on ifdown
* <che...@bankinf.banki.hu>
* Andi Kleen : kill double kfree on module
@@ -142,7 +144,12 @@ 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);
-
+static int ipv6_generate_address_variable_plen(struct in6_addr *address,
+ u8 dad_count,
+ const struct inet6_dev *idev,
+ unsigned int rcvd_prfx_len,
+ bool stable_privacy_mode);
+static void ipv6_plen_to_mask(int plen, struct in6_addr *net_mask);
#define IN6_ADDR_HSIZE_SHIFT 8
#define IN6_ADDR_HSIZE (1 << IN6_ADDR_HSIZE_SHIFT)
/*
@@ -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);
+ }
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;
+ }
+ 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);
+}
+
+static int ipv6_generate_address_variable_plen(struct in6_addr *address,
+ u8 dad_count,
+ const struct inet6_dev *idev,
+ unsigned int rcvd_prfx_len,
+ bool stable_privacy_mode)
+{
+ static DEFINE_SPINLOCK(lock);
+ static __u32 digest[SHA1_DIGEST_WORDS];
+ static __u32 workspace[SHA1_WORKSPACE_WORDS];
+
+ 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;
+
+ struct in6_addr ipv6_temp_addr;
+ struct in6_addr net_mask;
+ struct in6_addr secret;
+ struct in6_addr temp;
+ struct net *net = dev_net(idev->dev);
+ int i;
+
+ 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;
+ }
+
+ /* convert plen to mask */
+ ipv6_plen_to_mask(rcvd_prfx_len, &net_mask);
+ for (i = 0; i < 4; i++) {
+ /* network prefix */
+ ipv6_temp_addr.s6_addr32[i] = address->s6_addr32[i] &
net_mask.s6_addr32[i];
+ /* host id */
+ ipv6_temp_addr.s6_addr32[i] |= temp.s6_addr32[i] &
~net_mask.s6_addr32[i];
+ }
+
+ *address = ipv6_temp_addr;
+ return 0;
+}
+
static void ipv6_gen_mode_random_init(struct inet6_dev *idev)
{
struct ipv6_stable_secret *s = &idev->cnf.stable_secret;
diff -rupN net-next-5.10.0-rc2/net/ipv6/ndisc.c
net-next-patch-5.10.0-rc2/net/ipv6/ndisc.c
--- net-next-5.10.0-rc2/net/ipv6/ndisc.c 2020-11-10 08:46:01.091860289
+0100
+++ net-next-patch-5.10.0-rc2/net/ipv6/ndisc.c 2020-11-11 18:11:05.630883513
+0100
@@ -1244,6 +1244,8 @@ static void ndisc_router_discovery(struc
in6_dev->if_flags |= IF_RA_RCVD;
}
+ in6_dev->if_flags |= ra_msg->icmph.icmp6_slaac_var_plen ?
+ IF_RA_VAR_PLEN : 0;
/*
* Remember the managed/otherconf flags from most recently
* received RA message (RFC 2462) -- yoshfuji
