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Message-Id: <436f67a5a1be78dfb4a8bb5824d20ddc47130975.1427129103.git.hannes@stressinduktion.org>
Date: Mon, 23 Mar 2015 18:01:57 +0100
From: Hannes Frederic Sowa <hannes@...essinduktion.org>
To: netdev@...r.kernel.org
Cc: ek@...gle.com, fgont@...networks.com, lorenzo@...gle.com,
hideaki.yoshifuji@...aclelinux.com
Subject: [PATCH net-next 3/8] ipv6: generation of stable privacy addresses for link-local and autoconf
This patch implements the stable privacy address generation for
link-local and autoconf addresses as specified in RFC7217.
RID = F(Prefix, Net_Iface, Network_ID, DAD_Counter, secret_key)
is the RID (random identifier). As the hash function F we chose one
round of sha1. Prefix will be either the link-local prefix or the
router advertised one. As Net_Iface we use the MAC address of the
device. DAD_Counter and secret_key are implemented as specified.
We don't use Network_ID, as it couples the code too closely to other
subsystems. It is specified as optional in the RFC.
As Net_Iface we only use the MAC address: we simply have no stable
identifier in the kernel we could possibly use: because this code might
run very early, we cannot depend on names, as they might be changed by
user space early on during the boot process.
A new address generation mode is introduced,
IN6_ADDR_GEN_MODE_STABLE_PRIVACY. With iproute2 one can switch back to
none or eui64 address configuration mode although the stable_secret is
already set.
We refuse writes to ipv6/conf/all/stable_secret but only allow
ipv6/conf/default/stable_secret and the interface specific file to be
written to. The default stable_secret is used as the parameter for the
namespace, the interface specific can overwrite the secret, e.g. when
switching a network configuration from one system to another while
inheriting the secret.
Cc: Erik Kline <ek@...gle.com>
Cc: Fernando Gont <fgont@...networks.com>
Cc: Lorenzo Colitti <lorenzo@...gle.com>
Cc: YOSHIFUJI Hideaki/吉藤英明 <hideaki.yoshifuji@...aclelinux.com>
Signed-off-by: Hannes Frederic Sowa <hannes@...essinduktion.org>
---
include/uapi/linux/if_link.h | 1 +
net/ipv6/addrconf.c | 130 +++++++++++++++++++++++++++++++++++++++++--
2 files changed, 127 insertions(+), 4 deletions(-)
diff --git a/include/uapi/linux/if_link.h b/include/uapi/linux/if_link.h
index f5f5edd..7ffb18d 100644
--- a/include/uapi/linux/if_link.h
+++ b/include/uapi/linux/if_link.h
@@ -216,6 +216,7 @@ enum {
enum in6_addr_gen_mode {
IN6_ADDR_GEN_MODE_EUI64,
IN6_ADDR_GEN_MODE_NONE,
+ IN6_ADDR_GEN_MODE_STABLE_PRIVACY,
};
/* Bridge section */
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 5b967c8..6813268 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -131,6 +131,9 @@ static void ipv6_regen_rndid(unsigned long data);
static int ipv6_generate_eui64(u8 *eui, struct net_device *dev);
static int ipv6_count_addresses(struct inet6_dev *idev);
+static int ipv6_generate_stable_address(struct in6_addr *addr,
+ u8 dad_count,
+ const struct inet6_dev *idev);
/*
* Configured unicast address hash table
@@ -2302,6 +2305,11 @@ void addrconf_prefix_rcv(struct net_device *dev, u8 *opt, int len, bool sllao)
in6_dev->token.s6_addr + 8, 8);
read_unlock_bh(&in6_dev->lock);
tokenized = true;
+ } else if (in6_dev->addr_gen_mode ==
+ IN6_ADDR_GEN_MODE_STABLE_PRIVACY &&
+ !ipv6_generate_stable_address(&addr, 0,
+ in6_dev)) {
+ goto ok;
} else if (ipv6_generate_eui64(addr.s6_addr + 8, dev) &&
ipv6_inherit_eui64(addr.s6_addr + 8, in6_dev)) {
in6_dev_put(in6_dev);
@@ -2820,12 +2828,98 @@ static void addrconf_add_linklocal(struct inet6_dev *idev, const struct in6_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_generate_stable_address(struct in6_addr *address,
+ u8 dad_count,
+ const struct inet6_dev *idev)
+{
+ static const int idgen_retries = 3;
+
+ static DEFINE_SPINLOCK(lock);
+ static __u32 digest[SHA_DIGEST_WORDS];
+ static __u32 workspace[SHA_WORKSPACE_WORDS];
+
+ static union {
+ char __data[SHA_MESSAGE_BYTES];
+ struct {
+ struct in6_addr secret;
+ __be64 prefix;
+ unsigned char hwaddr[MAX_ADDR_LEN];
+ u8 dad_count;
+ } __packed;
+ } data;
+
+ struct in6_addr secret;
+ struct in6_addr temp;
+ struct net *net = dev_net(idev->dev);
+
+ BUILD_BUG_ON(sizeof(data.__data) != sizeof(data));
+
+ 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);
+
+ sha_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 = ((__be64)address->s6_addr32[0] << 32) |
+ (__be64)address->s6_addr32[1];
+ data.secret = secret;
+ data.dad_count = dad_count;
+
+ sha_transform(digest, data.__data, workspace);
+
+ temp = *address;
+ temp.s6_addr32[2] = digest[0];
+ temp.s6_addr32[3] = digest[1];
+
+ spin_unlock_bh(&lock);
+
+ if (ipv6_reserved_interfaceid(temp)) {
+ dad_count++;
+ if (dad_count > idgen_retries)
+ return -1;
+ goto retry;
+ }
+
+ *address = temp;
+ return 0;
+}
+
static void addrconf_addr_gen(struct inet6_dev *idev, bool prefix_route)
{
- if (idev->addr_gen_mode == IN6_ADDR_GEN_MODE_EUI64) {
- struct in6_addr addr;
+ struct in6_addr addr;
+
+ ipv6_addr_set(&addr, htonl(0xFE800000), 0, 0, 0);
- ipv6_addr_set(&addr, htonl(0xFE800000), 0, 0, 0);
+ if (idev->addr_gen_mode == IN6_ADDR_GEN_MODE_STABLE_PRIVACY) {
+ if (!ipv6_generate_stable_address(&addr, 0, idev))
+ addrconf_add_linklocal(idev, &addr);
+ else if (prefix_route)
+ addrconf_prefix_route(&addr, 64, idev->dev, 0, 0);
+ } else if (idev->addr_gen_mode == IN6_ADDR_GEN_MODE_EUI64) {
/* addrconf_add_linklocal also adds a prefix_route and we
* only need to care about prefix routes if ipv6_generate_eui64
* couldn't generate one.
@@ -4675,8 +4769,15 @@ static int inet6_set_link_af(struct net_device *dev, const struct nlattr *nla)
u8 mode = nla_get_u8(tb[IFLA_INET6_ADDR_GEN_MODE]);
if (mode != IN6_ADDR_GEN_MODE_EUI64 &&
- mode != IN6_ADDR_GEN_MODE_NONE)
+ mode != IN6_ADDR_GEN_MODE_NONE &&
+ mode != IN6_ADDR_GEN_MODE_STABLE_PRIVACY)
+ return -EINVAL;
+
+ if (mode == IN6_ADDR_GEN_MODE_STABLE_PRIVACY &&
+ !idev->cnf.stable_secret.initialized &&
+ !dev_net(dev)->ipv6.devconf_dflt->stable_secret.initialized)
return -EINVAL;
+
idev->addr_gen_mode = mode;
err = 0;
}
@@ -5093,8 +5194,12 @@ static int addrconf_sysctl_stable_secret(struct ctl_table *ctl, int write,
struct in6_addr addr;
char str[IPV6_MAX_STRLEN];
struct ctl_table lctl = *ctl;
+ struct net *net = ctl->extra2;
struct ipv6_stable_secret *secret = ctl->data;
+ if (&net->ipv6.devconf_all->stable_secret == ctl->data)
+ return -EIO;
+
lctl.maxlen = IPV6_MAX_STRLEN;
lctl.data = str;
@@ -5127,6 +5232,23 @@ static int addrconf_sysctl_stable_secret(struct ctl_table *ctl, int write,
secret->initialized = true;
secret->secret = addr;
+ if (&net->ipv6.devconf_dflt->stable_secret == ctl->data) {
+ struct net_device *dev;
+
+ for_each_netdev(net, dev) {
+ struct inet6_dev *idev = __in6_dev_get(dev);
+
+ if (idev) {
+ idev->addr_gen_mode =
+ IN6_ADDR_GEN_MODE_STABLE_PRIVACY;
+ }
+ }
+ } else {
+ struct inet6_dev *idev = ctl->extra1;
+
+ idev->addr_gen_mode = IN6_ADDR_GEN_MODE_STABLE_PRIVACY;
+ }
+
out:
rtnl_unlock();
--
2.1.0
--
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