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ipv6: generation of stable privacy addresses for link-local and autoconf

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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@google.com>
Cc: Fernando Gont <fgont@si6networks.com>
Cc: Lorenzo Colitti <lorenzo@google.com>
Cc: YOSHIFUJI Hideaki/吉藤英明 <hideaki.yoshifuji@miraclelinux.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Hannes Frederic Sowa 2015-03-23 23:36:01 +01:00 committed by David S. Miller
parent 3d1bec9932
commit 622c81d57b
2 changed files with 127 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/uapi/linux/if_link.h
View File

@ -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 */

130
net/ipv6/addrconf.c
View File

@ -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();