From 622c81d57b392cc9be836670eb464a4dfaa9adfe Mon Sep 17 00:00:00 2001 From: Hannes Frederic Sowa Date: Mon, 23 Mar 2015 23:36:01 +0100 Subject: [PATCH] ipv6: generation of stable privacy addresses for link-local and autoconf MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 Cc: Fernando Gont Cc: Lorenzo Colitti Cc: YOSHIFUJI Hideaki/吉藤英明 Signed-off-by: Hannes Frederic Sowa Signed-off-by: David S. Miller --- 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(); -- 2.7.4