Commit 969c5464 authored by Fernando Gont's avatar Fernando Gont Committed by David S. Miller
Browse files

ipv6: Implement draft-ietf-6man-rfc4941bis 

Implement the upcoming rev of RFC4941 (IPv6 temporary addresses):
https://tools.ietf.org/html/draft-ietf-6man-rfc4941bis-09



* Reduces the default Valid Lifetime to 2 days
  The number of extra addresses employed when Valid Lifetime was
  7 days exacerbated the stress caused on network
  elements/devices. Additionally, the motivation for temporary
  addresses is indeed privacy and reduced exposure. With a
  default Valid Lifetime of 7 days, an address that becomes
  revealed by active communication is reachable and exposed for
  one whole week. The only use case for a Valid Lifetime of 7
  days could be some application that is expecting to have long
  lived connections. But if you want to have a long lived
  connections, you shouldn't be using a temporary address in the
  first place. Additionally, in the era of mobile devices, general
  applications should nevertheless be prepared and robust to
  address changes (e.g. nodes swap wifi <-> 4G, etc.)

* Employs different IIDs for different prefixes
  To avoid network activity correlation among addresses configured
  for different prefixes

* Uses a simpler algorithm for IID generation
  No need to store "history" anywhere

Signed-off-by: default avatarFernando Gont <fgont@si6networks.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent a7defa75

Documentation/networking/ip-sysctl.rst

+1 −1
Original line number Diff line number Diff line
@@ -2065,7 +2065,7 @@ use_tempaddr - INTEGER 
temp_valid_lft - INTEGER

	valid lifetime (in seconds) for temporary addresses.



	Default: 604800 (7 days)

	Default: 172800 (2 days)



temp_prefered_lft - INTEGER

	Preferred lifetime (in seconds) for temporary addresses.

include/net/if_inet6.h

+0 −1
Original line number Diff line number Diff line
@@ -190,7 +190,6 @@ struct inet6_dev { 
	int			dead;



	u32			desync_factor;

	u8			rndid[8];

	struct list_head	tempaddr_list;



	struct in6_addr		token;

net/ipv6/addrconf.c

+39 −52
Original line number Diff line number Diff line
@@ -135,8 +135,7 @@ static inline void addrconf_sysctl_unregister(struct inet6_dev *idev) 
}

#endif



static void ipv6_regen_rndid(struct inet6_dev *idev);

static void ipv6_try_regen_rndid(struct inet6_dev *idev, struct in6_addr *tmpaddr);

static void ipv6_gen_rnd_iid(struct in6_addr *addr);



static int ipv6_generate_eui64(u8 *eui, struct net_device *dev);

static int ipv6_count_addresses(const struct inet6_dev *idev);
@@ -432,8 +431,7 @@ static struct inet6_dev *ipv6_add_dev(struct net_device *dev) 
	    dev->type == ARPHRD_SIT ||

	    dev->type == ARPHRD_NONE) {

		ndev->cnf.use_tempaddr = -1;

	} else

		ipv6_regen_rndid(ndev);

	}



	ndev->token = in6addr_any;
@@ -1306,29 +1304,21 @@ out: 
	in6_ifa_put(ifp);

}



static int ipv6_create_tempaddr(struct inet6_ifaddr *ifp,

				struct inet6_ifaddr *ift,

				bool block)

static int ipv6_create_tempaddr(struct inet6_ifaddr *ifp, bool block)

{

	struct inet6_dev *idev = ifp->idev;

	struct in6_addr addr, *tmpaddr;

	unsigned long tmp_tstamp, age;

	unsigned long regen_advance;

	struct ifa6_config cfg;

	int ret = 0;

	unsigned long now = jiffies;

	long max_desync_factor;

	s32 cnf_temp_preferred_lft;

	struct inet6_ifaddr *ift;

	struct ifa6_config cfg;

	long max_desync_factor;

	struct in6_addr addr;

	int ret = 0;



	write_lock_bh(&idev->lock);

	if (ift) {

		spin_lock_bh(&ift->lock);

		memcpy(&addr.s6_addr[8], &ift->addr.s6_addr[8], 8);

		spin_unlock_bh(&ift->lock);

		tmpaddr = &addr;

	} else {

		tmpaddr = NULL;

	}



retry:

	in6_dev_hold(idev);

	if (idev->cnf.use_tempaddr <= 0) {
@@ -1351,8 +1341,8 @@ retry: 
	}

	in6_ifa_hold(ifp);

	memcpy(addr.s6_addr, ifp->addr.s6_addr, 8);

	ipv6_try_regen_rndid(idev, tmpaddr);

	memcpy(&addr.s6_addr[8], idev->rndid, 8);

	ipv6_gen_rnd_iid(&addr);



	age = (now - ifp->tstamp) / HZ;



	regen_advance = idev->cnf.regen_max_retry *
@@ -1417,7 +1407,6 @@ retry: 
		in6_ifa_put(ifp);

		in6_dev_put(idev);

		pr_info("%s: retry temporary address regeneration\n", __func__);

		tmpaddr = &addr;

		write_lock_bh(&idev->lock);

		goto retry;

	}
@@ -2032,7 +2021,7 @@ static void addrconf_dad_stop(struct inet6_ifaddr *ifp, int dad_failed) 
		if (ifpub) {

			in6_ifa_hold(ifpub);

			spin_unlock_bh(&ifp->lock);

			ipv6_create_tempaddr(ifpub, ifp, true);

			ipv6_create_tempaddr(ifpub, true);

			in6_ifa_put(ifpub);

		} else {

			spin_unlock_bh(&ifp->lock);
@@ -2329,40 +2318,38 @@ static int ipv6_inherit_eui64(u8 *eui, struct inet6_dev *idev) 
	return err;

}



/* (re)generation of randomized interface identifier (RFC 3041 3.2, 3.5) */

static void ipv6_regen_rndid(struct inet6_dev *idev)

/* Generation of a randomized Interface Identifier

 * draft-ietf-6man-rfc4941bis, Section 3.3.1

 */



static void ipv6_gen_rnd_iid(struct in6_addr *addr)

{

regen:

	get_random_bytes(idev->rndid, sizeof(idev->rndid));

	idev->rndid[0] &= ~0x02;

	get_random_bytes(&addr->s6_addr[8], 8);



	/*

	 * <draft-ietf-ipngwg-temp-addresses-v2-00.txt>:

	 * check if generated address is not inappropriate

	/* <draft-ietf-6man-rfc4941bis-08.txt>, Section 3.3.1:

	 * check if generated address is not inappropriate:

	 *

	 *  - Reserved subnet anycast (RFC 2526)

	 *	11111101 11....11 1xxxxxxx

	 *  - ISATAP (RFC4214) 6.1

	 *	00-00-5E-FE-xx-xx-xx-xx

	 *  - value 0

	 * - Reserved IPv6 Interface Identifers

	 * - XXX: already assigned to an address on the device

	 */

	if (idev->rndid[0] == 0xfd &&

	    (idev->rndid[1]&idev->rndid[2]&idev->rndid[3]&idev->rndid[4]&idev->rndid[5]&idev->rndid[6]) == 0xff &&

	    (idev->rndid[7]&0x80))

		goto regen;

	if ((idev->rndid[0]|idev->rndid[1]) == 0) {

		if (idev->rndid[2] == 0x5e && idev->rndid[3] == 0xfe)



	/* Subnet-router anycast: 0000:0000:0000:0000 */

	if (!(addr->s6_addr32[2] | addr->s6_addr32[3]))

		goto regen;

		if ((idev->rndid[2]|idev->rndid[3]|idev->rndid[4]|idev->rndid[5]|idev->rndid[6]|idev->rndid[7]) == 0x00)



	/* IANA Ethernet block: 0200:5EFF:FE00:0000-0200:5EFF:FE00:5212

	 * Proxy Mobile IPv6:   0200:5EFF:FE00:5213

	 * IANA Ethernet block: 0200:5EFF:FE00:5214-0200:5EFF:FEFF:FFFF

	 */

	if (ntohl(addr->s6_addr32[2]) == 0x02005eff &&

	    (ntohl(addr->s6_addr32[3]) & 0Xff000000) == 0xfe000000)

		goto regen;

	}

}



static void  ipv6_try_regen_rndid(struct inet6_dev *idev, struct in6_addr *tmpaddr)

{

	if (tmpaddr && memcmp(idev->rndid, &tmpaddr->s6_addr[8], 8) == 0)

		ipv6_regen_rndid(idev);

	/* Reserved subnet anycast addresses */

	if (ntohl(addr->s6_addr32[2]) == 0xfdffffff &&

	    ntohl(addr->s6_addr32[3]) >= 0Xffffff80)

		goto regen;

}



/*
@@ -2544,7 +2531,7 @@ static void manage_tempaddrs(struct inet6_dev *idev, 
		 * no temporary address currently exists.

		 */

		read_unlock_bh(&idev->lock);

		ipv6_create_tempaddr(ifp, NULL, false);

		ipv6_create_tempaddr(ifp, false);

	} else {

		read_unlock_bh(&idev->lock);

	}
@@ -4531,7 +4518,7 @@ restart: 
						ifpub->regen_count = 0;

						spin_unlock(&ifpub->lock);

						rcu_read_unlock_bh();

						ipv6_create_tempaddr(ifpub, ifp, true);

						ipv6_create_tempaddr(ifpub, true);

						in6_ifa_put(ifpub);

						in6_ifa_put(ifp);

						rcu_read_lock_bh();

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