From: Johannes Berg <johannes.berg@xxxxxxxxx>
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 <johannes.berg@xxxxxxxxx>
---
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 428fb48a19fc..77992f1173c3 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -1672,6 +1672,13 @@ 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 34317cb6a6fc..9231bfdc7c92 100644
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -56,6 +56,7 @@ 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 4c413570efe8..ec117b65d5a5 100644
--- a/include/uapi/linux/ipv6.h
+++ b/include/uapi/linux/ipv6.h
@@ -175,6 +175,7 @@ enum {
DEVCONF_ACCEPT_RA_MIN_HOP_LIMIT,
DEVCONF_IGNORE_ROUTES_WITH_LINKDOWN,
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 35f880bcf626..e7dd0a0c5126 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -4673,6 +4673,7 @@ static inline void ipv6_store_devconf(struct ipv6_devconf *cnf,
/* we omit DEVCONF_STABLE_SECRET for now */
array[DEVCONF_USE_OIF_ADDRS_ONLY] = cnf->use_oif_addrs_only;
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)
@@ -5742,6 +5743,13 @@ 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 3e0f855e1bea..0737bc23ea39 100644
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -887,6 +887,7 @@ 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;
@@ -906,6 +907,14 @@ 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;
--
2.6.2
--
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