From adc176c5472214971d77c1a61c83db9b01e9cdc7 Mon Sep 17 00:00:00 2001 From: Erik Nordmark Date: Fri, 2 Dec 2016 14:00:08 -0800 Subject: [PATCH] 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 --- Documentation/networking/ip-sysctl.txt | 9 ++++++++ include/linux/ipv6.h | 1 + include/net/if_inet6.h | 1 + include/net/ndisc.h | 5 ++++- include/uapi/linux/ipv6.h | 1 + net/ipv6/addrconf.c | 22 ++++++++++++++++++- net/ipv6/ndisc.c | 29 +++++++++++++++++++++++--- net/ipv6/route.c | 2 +- 8 files changed, 64 insertions(+), 6 deletions(-) diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt index 5ca567fa6b8c..7dd65c9cf707 100644 --- a/Documentation/networking/ip-sysctl.txt +++ b/Documentation/networking/ip-sysctl.txt @@ -1734,6 +1734,15 @@ drop_unsolicited_na - BOOLEAN By default this is turned off. +enhanced_dad - BOOLEAN + Include a nonce option in the IPv6 neighbor solicitation messages used for + duplicate address detection per RFC7527. A received DAD NS will only signal + a duplicate address if the nonce is different. This avoids any false + detection of duplicates due to loopback of the NS messages that we send. + The nonce option will be sent on an interface unless both of + conf/{all,interface}/enhanced_dad are set to FALSE. + Default: TRUE + icmp/*: ratelimit - INTEGER Limit the maximal rates for sending ICMPv6 packets. diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h index 3f95233b2733..671d014e6429 100644 --- a/include/linux/ipv6.h +++ b/include/linux/ipv6.h @@ -68,6 +68,7 @@ struct ipv6_devconf { #ifdef CONFIG_IPV6_SEG6_HMAC __s32 seg6_require_hmac; #endif + __u32 enhanced_dad; struct ctl_table_header *sysctl_header; }; diff --git a/include/net/if_inet6.h b/include/net/if_inet6.h index b0576cb2ab25..0fa4c324b713 100644 --- a/include/net/if_inet6.h +++ b/include/net/if_inet6.h @@ -55,6 +55,7 @@ struct inet6_ifaddr { __u8 stable_privacy_retry; __u16 scope; + __u64 dad_nonce; unsigned long cstamp; /* created timestamp */ unsigned long tstamp; /* updated timestamp */ diff --git a/include/net/ndisc.h b/include/net/ndisc.h index be1fe2283254..d562a2fe4860 100644 --- a/include/net/ndisc.h +++ b/include/net/ndisc.h @@ -31,6 +31,7 @@ enum { ND_OPT_PREFIX_INFO = 3, /* RFC2461 */ ND_OPT_REDIRECT_HDR = 4, /* RFC2461 */ ND_OPT_MTU = 5, /* RFC2461 */ + ND_OPT_NONCE = 14, /* RFC7527 */ __ND_OPT_ARRAY_MAX, ND_OPT_ROUTE_INFO = 24, /* RFC4191 */ ND_OPT_RDNSS = 25, /* RFC5006 */ @@ -121,6 +122,7 @@ struct ndisc_options { #define nd_opts_pi_end nd_opt_array[__ND_OPT_PREFIX_INFO_END] #define nd_opts_rh nd_opt_array[ND_OPT_REDIRECT_HDR] #define nd_opts_mtu nd_opt_array[ND_OPT_MTU] +#define nd_opts_nonce nd_opt_array[ND_OPT_NONCE] #define nd_802154_opts_src_lladdr nd_802154_opt_array[ND_OPT_SOURCE_LL_ADDR] #define nd_802154_opts_tgt_lladdr nd_802154_opt_array[ND_OPT_TARGET_LL_ADDR] @@ -398,7 +400,8 @@ void ndisc_cleanup(void); int ndisc_rcv(struct sk_buff *skb); 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); void ndisc_send_rs(struct net_device *dev, const struct in6_addr *saddr, const struct in6_addr *daddr); diff --git a/include/uapi/linux/ipv6.h b/include/uapi/linux/ipv6.h index 53561be1ac21..eaf65dc82e22 100644 --- a/include/uapi/linux/ipv6.h +++ b/include/uapi/linux/ipv6.h @@ -181,6 +181,7 @@ enum { DEVCONF_RTR_SOLICIT_MAX_INTERVAL, DEVCONF_SEG6_ENABLED, DEVCONF_SEG6_REQUIRE_HMAC, + DEVCONF_ENHANCED_DAD, DEVCONF_MAX }; diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c index 4c387dc338e3..c1e124bc8e1e 100644 --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -242,6 +242,7 @@ static struct ipv6_devconf ipv6_devconf __read_mostly = { #ifdef CONFIG_IPV6_SEG6_HMAC .seg6_require_hmac = 0, #endif + .enhanced_dad = 1, }; static struct ipv6_devconf ipv6_devconf_dflt __read_mostly = { @@ -292,6 +293,7 @@ static struct ipv6_devconf ipv6_devconf_dflt __read_mostly = { #ifdef CONFIG_IPV6_SEG6_HMAC .seg6_require_hmac = 0, #endif + .enhanced_dad = 1, }; /* Check if a valid qdisc is available */ @@ -3735,12 +3737,21 @@ static void addrconf_dad_kick(struct inet6_ifaddr *ifp) { unsigned long rand_num; struct inet6_dev *idev = ifp->idev; + u64 nonce; if (ifp->flags & IFA_F_OPTIMISTIC) rand_num = 0; else rand_num = prandom_u32() % (idev->cnf.rtr_solicit_delay ? : 1); + nonce = 0; + if (idev->cnf.enhanced_dad || + dev_net(idev->dev)->ipv6.devconf_all->enhanced_dad) { + do + get_random_bytes(&nonce, 6); + while (nonce == 0); + } + ifp->dad_nonce = nonce; ifp->dad_probes = idev->cnf.dad_transmits; addrconf_mod_dad_work(ifp, rand_num); } @@ -3918,7 +3929,8 @@ static void addrconf_dad_work(struct work_struct *w) /* send a neighbour solicitation for our addr */ addrconf_addr_solict_mult(&ifp->addr, &mcaddr); - ndisc_send_ns(ifp->idev->dev, &ifp->addr, &mcaddr, &in6addr_any); + ndisc_send_ns(ifp->idev->dev, &ifp->addr, &mcaddr, &in6addr_any, + ifp->dad_nonce); out: in6_ifa_put(ifp); rtnl_unlock(); @@ -4962,6 +4974,7 @@ static inline void ipv6_store_devconf(struct ipv6_devconf *cnf, #ifdef CONFIG_IPV6_SEG6_HMAC array[DEVCONF_SEG6_REQUIRE_HMAC] = cnf->seg6_require_hmac; #endif + array[DEVCONF_ENHANCED_DAD] = cnf->enhanced_dad; } static inline size_t inet6_ifla6_size(void) @@ -6069,6 +6082,13 @@ static const struct ctl_table addrconf_sysctl[] = { .proc_handler = proc_dointvec, }, #endif + { + .procname = "enhanced_dad", + .data = &ipv6_devconf.enhanced_dad, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec, + }, { /* sentinel */ } 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 diff --git a/net/ipv6/route.c b/net/ipv6/route.c index b317bb135ed4..aac7818e2e0f 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -527,7 +527,7 @@ static void rt6_probe_deferred(struct work_struct *w) container_of(w, struct __rt6_probe_work, work); addrconf_addr_solict_mult(&work->target, &mcaddr); - ndisc_send_ns(work->dev, &work->target, &mcaddr, NULL); + ndisc_send_ns(work->dev, &work->target, &mcaddr, NULL, 0); dev_put(work->dev); kfree(work); }