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Date: Mon, 6 Apr 2020 13:26:34 -0300
From: Fernando Gont <fgont@...networks.com>
To: netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH] [net-next] IPv6 RFC4941bis (Privacy/temporary addresses)
Folks,
Any thoughts?
Thanks!
Fernando
On 2/4/20 14:06, Fernando Gont wrote:
> Folks,
>
> This patch the upcoming revision of RFC4941:
> https://tools.ietf.org/html/draft-ietf-6man-rfc4941bis-08 .
>
> Namely,
>
> * Reduces the default Valid Lifetime to 2 days
> This reduces stress on network elements, among other things
>
> * 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
>
> P.S.: The patch is also available here:
> https://www.gont.com.ar/code/fgont-patch-linux-net-next-rfc4941bis.txt
>
> ---- cut here ----
> diff --git Documentation/networking/ip-sysctl.txt
> Documentation/networking/ip-sysctl.txt
> index ee961d322d93..db1ee7340090 100644
> --- Documentation/networking/ip-sysctl.txt
> +++ Documentation/networking/ip-sysctl.txt
> @@ -1807,7 +1807,7 @@ 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.
> diff --git include/net/addrconf.h include/net/addrconf.h
> index e0eabe58aa8b..1bd21ee035bf 100644
> --- include/net/addrconf.h
> +++ include/net/addrconf.h
> @@ -8,7 +8,7 @@
>
> #define MIN_VALID_LIFETIME (2*3600) /* 2 hours */
>
> -#define TEMP_VALID_LIFETIME (7*86400)
> +#define TEMP_VALID_LIFETIME (2*86400)
> #define TEMP_PREFERRED_LIFETIME (86400)
> #define REGEN_MAX_RETRY (3)
> #define MAX_DESYNC_FACTOR (600)
> diff --git include/net/if_inet6.h include/net/if_inet6.h
> index a01981d7108f..212eb278bda6 100644
> --- include/net/if_inet6.h
> +++ include/net/if_inet6.h
> @@ -190,7 +190,6 @@ struct inet6_dev {
> int dead;
>
> u32 desync_factor;
> - u8 rndid[8];
> struct list_head tempaddr_list;
>
> struct in6_addr token;
> diff --git net/ipv6/addrconf.c net/ipv6/addrconf.c
> index a11fd4d67832..da34dbbd0195 100644
> --- net/ipv6/addrconf.c
> +++ net/ipv6/addrconf.c
> @@ -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;
>
> @@ -1306,12 +1304,11 @@ static void ipv6_del_addr(struct inet6_ifaddr *ifp)
> 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;
> + struct in6_addr addr;
> + struct inet6_ifaddr *ift;
> unsigned long tmp_tstamp, age;
> unsigned long regen_advance;
> struct ifa6_config cfg;
> @@ -1321,14 +1318,7 @@ static int ipv6_create_tempaddr(struct
> inet6_ifaddr *ifp,
> s32 cnf_temp_preferred_lft;
>
> 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 @@ static int ipv6_create_tempaddr(struct
> inet6_ifaddr *ifp,
> }
> 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 @@ static int ipv6_create_tempaddr(struct
> inet6_ifaddr *ifp,
> 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);
> @@ -2329,42 +2318,39 @@ 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 IPv6 Interface Identifers
> + *
> (http://www.iana.org/assignments/ipv6-interface-ids/ipv6-interface-ids.xhtml)
>
> *
> - * - Reserved subnet anycast (RFC 2526)
> - * 11111101 11....11 1xxxxxxx
> - * - ISATAP (RFC4214) 6.1
> - * 00-00-5E-FE-xx-xx-xx-xx
> - * - value 0
> * - 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))
> +
> + /* Subnet-router anycast: 0000:0000:0000:0000 */
> + if (!(addr->s6_addr32[2] | addr->s6_addr32[3]))
> goto regen;
> - if ((idev->rndid[0]|idev->rndid[1]) == 0) {
> - if (idev->rndid[2] == 0x5e && idev->rndid[3] == 0xfe)
> - goto regen;
> - if
> ((idev->rndid[2]|idev->rndid[3]|idev->rndid[4]|idev->rndid[5]|idev->rndid[6]|idev->rndid[7])
> == 0x00)
> - 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);
> + /* 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;
> +
> + /* Reserved subnet anycast addresses */
> + if (ntohl(addr->s6_addr32[2]) == 0xfdffffff &&
> ntohl(addr->s6_addr32[3]) >= 0Xffffff80)
> + goto regen;
> }
>
> +
> /*
> * Add prefix route.
> */
> @@ -2544,7 +2530,7 @@ 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);
> }
> @@ -4539,7 +4525,7 @@ static void addrconf_verify_rtnl(void)
> 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();
> ---- cut here ----
>
> Thanks,
--
Fernando Gont
SI6 Networks
e-mail: fgont@...networks.com
PGP Fingerprint: 6666 31C6 D484 63B2 8FB1 E3C4 AE25 0D55 1D4E 7492
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