From adc176c5472214971d77c1a61c83db9b01e9cdc7 Mon Sep 17 00:00:00 2001 From: Erik Nordmark Date: Fri, 2 Dec 2016 14:00:08 -0800 Subject: ipv6 addrconf: Implemented enhanced DAD (RFC7527) Implemented RFC7527 Enhanced DAD. IPv6 duplicate address detection can fail if there is some temporary loopback of Ethernet frames. RFC7527 solves this by including a random nonce in the NS messages used for DAD, and if an NS is received with the same nonce it is assumed to be a looped back DAD probe and is ignored. RFC7527 is enabled by default. Can be disabled by setting both of conf/{all,interface}/enhanced_dad to zero. Signed-off-by: Erik Nordmark Signed-off-by: Bob Gilligan Reviewed-by: Hannes Frederic Sowa Signed-off-by: David S. Miller --- net/ipv6/ndisc.c | 29 ++++++++++++++++++++++++++--- 1 file changed, 26 insertions(+), 3 deletions(-) (limited to 'net/ipv6/ndisc.c') diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c index d8e671457d10..7ebac630d3c6 100644 --- a/net/ipv6/ndisc.c +++ b/net/ipv6/ndisc.c @@ -233,6 +233,7 @@ struct ndisc_options *ndisc_parse_options(const struct net_device *dev, case ND_OPT_SOURCE_LL_ADDR: case ND_OPT_TARGET_LL_ADDR: case ND_OPT_MTU: + case ND_OPT_NONCE: case ND_OPT_REDIRECT_HDR: if (ndopts->nd_opt_array[nd_opt->nd_opt_type]) { ND_PRINTK(2, warn, @@ -568,7 +569,8 @@ static void ndisc_send_unsol_na(struct net_device *dev) } void ndisc_send_ns(struct net_device *dev, const struct in6_addr *solicit, - const struct in6_addr *daddr, const struct in6_addr *saddr) + const struct in6_addr *daddr, const struct in6_addr *saddr, + u64 nonce) { struct sk_buff *skb; struct in6_addr addr_buf; @@ -588,6 +590,8 @@ void ndisc_send_ns(struct net_device *dev, const struct in6_addr *solicit, if (inc_opt) optlen += ndisc_opt_addr_space(dev, NDISC_NEIGHBOUR_SOLICITATION); + if (nonce != 0) + optlen += 8; skb = ndisc_alloc_skb(dev, sizeof(*msg) + optlen); if (!skb) @@ -605,6 +609,13 @@ void ndisc_send_ns(struct net_device *dev, const struct in6_addr *solicit, ndisc_fill_addr_option(skb, ND_OPT_SOURCE_LL_ADDR, dev->dev_addr, NDISC_NEIGHBOUR_SOLICITATION); + if (nonce != 0) { + u8 *opt = skb_put(skb, 8); + + opt[0] = ND_OPT_NONCE; + opt[1] = 8 >> 3; + memcpy(opt + 2, &nonce, 6); + } ndisc_send_skb(skb, daddr, saddr); } @@ -693,12 +704,12 @@ static void ndisc_solicit(struct neighbour *neigh, struct sk_buff *skb) "%s: trying to ucast probe in NUD_INVALID: %pI6\n", __func__, target); } - ndisc_send_ns(dev, target, target, saddr); + ndisc_send_ns(dev, target, target, saddr, 0); } else if ((probes -= NEIGH_VAR(neigh->parms, APP_PROBES)) < 0) { neigh_app_ns(neigh); } else { addrconf_addr_solict_mult(target, &mcaddr); - ndisc_send_ns(dev, target, &mcaddr, saddr); + ndisc_send_ns(dev, target, &mcaddr, saddr, 0); } } @@ -742,6 +753,7 @@ static void ndisc_recv_ns(struct sk_buff *skb) int dad = ipv6_addr_any(saddr); bool inc; int is_router = -1; + u64 nonce = 0; if (skb->len < sizeof(struct nd_msg)) { ND_PRINTK(2, warn, "NS: packet too short\n"); @@ -786,6 +798,8 @@ static void ndisc_recv_ns(struct sk_buff *skb) return; } } + if (ndopts.nd_opts_nonce) + memcpy(&nonce, (u8 *)(ndopts.nd_opts_nonce + 1), 6); inc = ipv6_addr_is_multicast(daddr); @@ -794,6 +808,15 @@ static void ndisc_recv_ns(struct sk_buff *skb) have_ifp: if (ifp->flags & (IFA_F_TENTATIVE|IFA_F_OPTIMISTIC)) { if (dad) { + if (nonce != 0 && ifp->dad_nonce == nonce) { + u8 *np = (u8 *)&nonce; + /* Matching nonce if looped back */ + ND_PRINTK(2, notice, + "%s: IPv6 DAD loopback for address %pI6c nonce %pM ignored\n", + ifp->idev->dev->name, + &ifp->addr, np); + goto out; + } /* * We are colliding with another node * who is doing DAD -- cgit