net: ipv6: Add a sysctl to make optimistic addresses useful candidates
Add a sysctl that causes an interface's optimistic addresses
to be considered equivalent to other non-deprecated addresses
for source address selection purposes. Preferred addresses
will still take precedence over optimistic addresses, subject
to other ranking in the source address selection algorithm.
This is useful where different interfaces are connected to
different networks from different ISPs (e.g., a cell network
and a home wifi network).
The current behaviour complies with RFC 3484/6724, and it
makes sense if the host has only one interface, or has
multiple interfaces on the same network (same or cooperating
administrative domain(s), but not in the multiple distinct
networks case.
For example, if a mobile device has an IPv6 address on an LTE
network and then connects to IPv6-enabled wifi, while the wifi
IPv6 address is undergoing DAD, IPv6 connections will try use
the wifi default route with the LTE IPv6 address, and will get
stuck until they time out.
Also, because optimistic nodes can receive frames, issue
an RTM_NEWADDR as soon as DAD starts (with the IFA_F_OPTIMSTIC
flag appropriately set). A second RTM_NEWADDR is sent if DAD
completes (the address flags have changed), otherwise an
RTM_DELADDR is sent.
Also: add an entry in ip-sysctl.txt for optimistic_dad.
[backport of net-next 7fd2561e4ebdd070ebba6d3326c4c5b13942323f]
Signed-off-by: Erik Kline <ek@google.com>
Acked-by: Lorenzo Colitti <lorenzo@google.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Bug: 17769720
Change-Id: I440a9b8c788db6767d191bbebfd2dff481aa9e0d
diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index ec3ecd2..4fc32bf 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -1285,6 +1285,19 @@
race condition where the sender deletes the cached link-layer address
prior to receiving a response to a previous solicitation."
+optimistic_dad - BOOLEAN
+ Whether to perform Optimistic Duplicate Address Detection (RFC 4429).
+ 0: disabled (default)
+ 1: enabled
+
+use_optimistic - BOOLEAN
+ If enabled, do not classify optimistic addresses as deprecated during
+ source address selection. Preferred addresses will still be chosen
+ before optimistic addresses, subject to other ranking in the source
+ address selection algorithm.
+ 0: disabled (default)
+ 1: enabled
+
icmp/*:
ratelimit - INTEGER
Limit the maximal rates for sending ICMPv6 packets.
diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index 2789258..8f53d4c 100644
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -166,6 +166,7 @@
__s32 accept_source_route;
#ifdef CONFIG_IPV6_OPTIMISTIC_DAD
__s32 optimistic_dad;
+ __s32 use_optimistic;
#endif
#ifdef CONFIG_IPV6_MROUTE
__s32 mc_forwarding;
@@ -217,6 +218,7 @@
DEVCONF_FORCE_TLLAO,
DEVCONF_ACCEPT_RA_PREFIX_ROUTE,
DEVCONF_ACCEPT_RA_RT_TABLE,
+ DEVCONF_USE_OPTIMISTIC,
DEVCONF_MAX
};
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 6f0125d..a5ae270 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -966,6 +966,9 @@
#endif
IPV6_SADDR_RULE_ORCHID,
IPV6_SADDR_RULE_PREFIX,
+#ifdef CONFIG_IPV6_OPTIMISTIC_DAD
+ IPV6_SADDR_RULE_NOT_OPTIMISTIC,
+#endif
IPV6_SADDR_RULE_MAX
};
@@ -993,6 +996,15 @@
return 0;
}
+static inline bool ipv6_use_optimistic_addr(struct inet6_dev *idev)
+{
+#ifdef CONFIG_IPV6_OPTIMISTIC_DAD
+ return idev && idev->cnf.optimistic_dad && idev->cnf.use_optimistic;
+#else
+ return false;
+#endif
+}
+
static int ipv6_get_saddr_eval(struct net *net,
struct ipv6_saddr_score *score,
struct ipv6_saddr_dst *dst,
@@ -1053,10 +1065,16 @@
score->scopedist = ret;
break;
case IPV6_SADDR_RULE_PREFERRED:
+ {
/* Rule 3: Avoid deprecated and optimistic addresses */
+ u8 avoid = IFA_F_DEPRECATED;
+
+ if (!ipv6_use_optimistic_addr(score->ifa->idev))
+ avoid |= IFA_F_OPTIMISTIC;
ret = ipv6_saddr_preferred(score->addr_type) ||
- !(score->ifa->flags & (IFA_F_DEPRECATED|IFA_F_OPTIMISTIC));
+ !(score->ifa->flags & avoid);
break;
+ }
#ifdef CONFIG_IPV6_MIP6
case IPV6_SADDR_RULE_HOA:
{
@@ -1102,6 +1120,14 @@
score->matchlen = ret = ipv6_addr_diff(&score->ifa->addr,
dst->addr);
break;
+#ifdef CONFIG_IPV6_OPTIMISTIC_DAD
+ case IPV6_SADDR_RULE_NOT_OPTIMISTIC:
+ /* Optimistic addresses still have lower precedence than other
+ * preferred addresses.
+ */
+ ret = !(score->ifa->flags & IFA_F_OPTIMISTIC);
+ break;
+#endif
default:
ret = 0;
}
@@ -3061,8 +3087,15 @@
* Optimistic nodes can start receiving
* Frames right away
*/
- if (ifp->flags & IFA_F_OPTIMISTIC)
+ if (ifp->flags & IFA_F_OPTIMISTIC) {
ip6_ins_rt(ifp->rt);
+ if (ipv6_use_optimistic_addr(idev)) {
+ /* Because optimistic nodes can use this address,
+ * notify listeners. If DAD fails, RTM_DELADDR is sent.
+ */
+ ipv6_ifa_notify(RTM_NEWADDR, ifp);
+ }
+ }
addrconf_dad_kick(ifp);
out:
@@ -4013,6 +4046,7 @@
array[DEVCONF_ACCEPT_SOURCE_ROUTE] = cnf->accept_source_route;
#ifdef CONFIG_IPV6_OPTIMISTIC_DAD
array[DEVCONF_OPTIMISTIC_DAD] = cnf->optimistic_dad;
+ array[DEVCONF_USE_OPTIMISTIC] = cnf->use_optimistic;
#endif
#ifdef CONFIG_IPV6_MROUTE
array[DEVCONF_MC_FORWARDING] = cnf->mc_forwarding;
@@ -4666,6 +4700,14 @@
.proc_handler = proc_dointvec,
},
+ {
+ .procname = "use_optimistic",
+ .data = &ipv6_devconf.use_optimistic,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec,
+
+ },
#endif
#ifdef CONFIG_IPV6_MROUTE
{