Return-path: Received: from s3.sipsolutions.net ([5.9.151.49]:58002 "EHLO sipsolutions.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932246AbbDJHy0 (ORCPT ); Fri, 10 Apr 2015 03:54:26 -0400 From: Johannes Berg To: netdev@vger.kernel.org, linux-wireless@vger.kernel.org Cc: matti.gottlieb@intel.com, Johannes Berg Subject: [PATCH 4/4] ipv6: add option to drop unsolicited neighbor advertisements Date: Fri, 10 Apr 2015 09:54:14 +0200 Message-Id: <1428652454-1224-4-git-send-email-johannes@sipsolutions.net> (sfid-20150410_095449_796026_EB40EBD8) In-Reply-To: <1428652454-1224-1-git-send-email-johannes@sipsolutions.net> References: <1428652454-1224-1-git-send-email-johannes@sipsolutions.net> Sender: linux-wireless-owner@vger.kernel.org List-ID: From: Johannes Berg In certain 802.11 wireless deployments, there will be NA proxies that use knowledge of the network to correctly answer requests. To prevent unsolicitd advertisements on the shared medium from being a problem, on such deployments wireless needs to drop them. Enable this by providing an option called "drop_unsolicited_na". Signed-off-by: Johannes Berg --- Documentation/networking/ip-sysctl.txt | 7 +++++++ include/linux/ipv6.h | 1 + include/uapi/linux/ipv6.h | 1 + net/ipv6/addrconf.c | 8 ++++++++ net/ipv6/ndisc.c | 9 +++++++++ 5 files changed, 26 insertions(+) diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt index f6f32c21edaf..b0981c586fc4 100644 --- a/Documentation/networking/ip-sysctl.txt +++ b/Documentation/networking/ip-sysctl.txt @@ -1584,6 +1584,13 @@ drop_unicast_in_l2_multicast - BOOLEAN By default this is turned off. +drop_unsolicited_na - BOOLEAN + Drop all unsolicited neighbor advertisements, for example if there's + a known good NA proxy on the network and such frames need not be used + (or in the case of 802.11, must not be used to prevent attacks.) + + By default this is turned off. + icmp/*: ratelimit - INTEGER Limit the maximal rates for sending ICMPv6 packets. diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h index 1ec287a37e1d..cef258173a9d 100644 --- a/include/linux/ipv6.h +++ b/include/linux/ipv6.h @@ -54,6 +54,7 @@ struct ipv6_devconf { __s32 ndisc_notify; __s32 suppress_frag_ndisc; __s32 accept_ra_mtu; + __s32 drop_unsolicited_na; struct ipv6_stable_secret { bool initialized; struct in6_addr secret; diff --git a/include/uapi/linux/ipv6.h b/include/uapi/linux/ipv6.h index 5a7061d690cb..73d7f1df6fe1 100644 --- a/include/uapi/linux/ipv6.h +++ b/include/uapi/linux/ipv6.h @@ -172,6 +172,7 @@ enum { DEVCONF_ACCEPT_RA_MTU, DEVCONF_STABLE_SECRET, DEVCONF_DROP_UNICAST_IN_L2_MULTICAST, + DEVCONF_DROP_UNSOLICITED_NA, DEVCONF_MAX }; diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c index c017edf04f30..6d5a680085e8 100644 --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -4585,6 +4585,7 @@ static inline void ipv6_store_devconf(struct ipv6_devconf *cnf, array[DEVCONF_ACCEPT_RA_MTU] = cnf->accept_ra_mtu; /* we omit DEVCONF_STABLE_SECRET for now */ array[DEVCONF_DROP_UNICAST_IN_L2_MULTICAST] = cnf->drop_unicast_in_l2_multicast; + array[DEVCONF_DROP_UNSOLICITED_NA] = cnf->drop_unsolicited_na; } static inline size_t inet6_ifla6_size(void) @@ -5591,6 +5592,13 @@ static struct addrconf_sysctl_table .proc_handler = proc_dointvec, }, { + .procname = "drop_unsolicited_na", + .data = &ipv6_devconf.drop_unsolicited_na, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec, + }, + { /* sentinel */ } }, diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c index c283827d60e2..7291b91e359b 100644 --- a/net/ipv6/ndisc.c +++ b/net/ipv6/ndisc.c @@ -868,6 +868,7 @@ static void ndisc_recv_na(struct sk_buff *skb) offsetof(struct nd_msg, opt)); struct ndisc_options ndopts; struct net_device *dev = skb->dev; + struct inet6_dev *idev = __in6_dev_get(dev); struct inet6_ifaddr *ifp; struct neighbour *neigh; @@ -887,6 +888,14 @@ static void ndisc_recv_na(struct sk_buff *skb) return; } + /* For some 802.11 wireless deployments (and possibly other networks), + * there will be a NA proxy and unsolicitd packets are attacks + * and thus should not be accepted. + */ + if (idev && idev->cnf.drop_unsolicited_na && + !msg->icmph.icmp6_solicited) + return; + if (!ndisc_parse_options(msg->opt, ndoptlen, &ndopts)) { ND_PRINTK(2, warn, "NS: invalid ND option\n"); return; -- 2.1.4