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ipv6: Add net.ipv6.conf.*.accept_ra_defrtr_table sysctl.

RFC PATCH New Ben Jencks 1 participant 1 message Aug 22, 2012

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Networking Network drivers Documentation IPv4/IPv6 +1 more subsystems
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Ben Jencks

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RFC PATCH 1/1 ipv6: Add net.ipv6.conf.*.accept_ra_defrtr_table sysctl.

Allows configuration of the routing table to which default routes from RAs are added on a per-interface basis.

One use case where this is required is a multi-homed router advertising multiple prefixes, one for each upstream. The proper routing policy is something like:

0: from all lookup local
10: from all lookup main
20: from <prefix1> lookup provider1
30: from <prefix2> lookup provider2

with directly connected and internal routes in main, and default routes from providers 1 and 2 in their respective tables. With static routes this is straightforward; if the route for either or both providers is received via RA this configuration option becomes necessary to put the routes in the appropriate tables.

Signed-off-by Ben Jencks <[email protected]>

---
Patch is against v3.5.2, but applies cleanly to master as of today.

Looking for feedback on:
* Is this a worthwhile feature? Did I miss a good way to do this in userspace?
* Is a sysctl the right place to configure it? I know it's discouraged to add new ones, but it seems to fit best with the other similar configuration options.
* Is the rt6_purge_dflt_routers behavior correct? Should addrconf_fixup_forwarding be modified so that in the single device case it only purges from that device's table?

 Documentation/networking/ip-sysctl.txt |    6 +++++
 include/linux/ipv6.h                   |    2 ++
 include/linux/sysctl.h                 |    1 +
 kernel/sysctl_binary.c                 |    1 +
 net/ipv6/addrconf.c                    |   10 +++++++
 net/ipv6/route.c                       |   45 ++++++++++++++++++++++----------
 6 files changed, 51 insertions(+), 14 deletions(-)
Documentation/networking/ip-sysctl.txt +6 -0
index 6f896b9..0d0947a 100644
@@ -1085,6 +1085,12 @@ accept_ra_defrtr - BOOLEAN
 	Functional default: enabled if accept_ra is enabled.
 			    disabled if accept_ra is disabled.
 
+accept_ra_defrtr_table - INTEGER
+	Routing table into which to put default route learned via Router
+	Advertisement.
+
+	Functional default: "main" routing table (254)
+
 accept_ra_pinfo - BOOLEAN
 	Learn Prefix Information in Router Advertisement.
include/linux/ipv6.h +2 -0
index 8260ef7..fa9b4fe 100644
@@ -153,6 +153,7 @@ struct ipv6_devconf {
 #endif
 	__s32		max_addresses;
 	__s32		accept_ra_defrtr;
+	__s32		accept_ra_defrtr_table;
 	__s32		accept_ra_pinfo;
 #ifdef CONFIG_IPV6_ROUTER_PREF
 	__s32		accept_ra_rtr_pref;

@@ -202,6 +203,7 @@ enum {
 	DEVCONF_MAX_ADDRESSES,
 	DEVCONF_FORCE_MLD_VERSION,
 	DEVCONF_ACCEPT_RA_DEFRTR,
+	DEVCONF_ACCEPT_RA_DEFRTR_TABLE,
 	DEVCONF_ACCEPT_RA_PINFO,
 	DEVCONF_ACCEPT_RA_RTR_PREF,
 	DEVCONF_RTR_PROBE_INTERVAL,
include/linux/sysctl.h +1 -0
index c34b4c8..80115c8 100644
@@ -568,6 +568,7 @@ enum {
 	NET_IPV6_ACCEPT_RA_RT_INFO_MAX_PLEN=22,
 	NET_IPV6_PROXY_NDP=23,
 	NET_IPV6_ACCEPT_SOURCE_ROUTE=25,
+	NET_IPV6_ACCEPT_RA_DEFRTR_TABLE=26,
 	__NET_IPV6_MAX
 };
kernel/sysctl_binary.c +1 -0
index a650694..da964f3 100644
@@ -517,6 +517,7 @@ static const struct bin_table bin_net_ipv6_conf_var_table[] = {
 	{ CTL_INT,	NET_IPV6_MAX_ADDRESSES,			"max_addresses" },
 	{ CTL_INT,	NET_IPV6_FORCE_MLD_VERSION,		"force_mld_version" },
 	{ CTL_INT,	NET_IPV6_ACCEPT_RA_DEFRTR,		"accept_ra_defrtr" },
+	{ CTL_INT,	NET_IPV6_ACCEPT_RA_DEFRTR_TABLE,	"accept_ra_defrtr_table" },
 	{ CTL_INT,	NET_IPV6_ACCEPT_RA_PINFO,		"accept_ra_pinfo" },
 	{ CTL_INT,	NET_IPV6_ACCEPT_RA_RTR_PREF,		"accept_ra_rtr_pref" },
 	{ CTL_INT,	NET_IPV6_RTR_PROBE_INTERVAL,		"router_probe_interval" },
net/ipv6/addrconf.c +10 -0
index 8f6411c..2bdb96c 100644
@@ -188,6 +188,7 @@ static struct ipv6_devconf ipv6_devconf __read_mostly = {
 #endif
 	.max_addresses		= IPV6_MAX_ADDRESSES,
 	.accept_ra_defrtr	= 1,
+	.accept_ra_defrtr_table	= RT6_TABLE_DFLT,
 	.accept_ra_pinfo	= 1,
 #ifdef CONFIG_IPV6_ROUTER_PREF
 	.accept_ra_rtr_pref	= 1,

@@ -222,6 +223,7 @@ static struct ipv6_devconf ipv6_devconf_dflt __read_mostly = {
 #endif
 	.max_addresses		= IPV6_MAX_ADDRESSES,
 	.accept_ra_defrtr	= 1,
+	.accept_ra_defrtr_table	= RT6_TABLE_DFLT,
 	.accept_ra_pinfo	= 1,
 #ifdef CONFIG_IPV6_ROUTER_PREF
 	.accept_ra_rtr_pref	= 1,

@@ -3894,6 +3896,7 @@ static inline void ipv6_store_devconf(struct ipv6_devconf *cnf,
 #endif
 	array[DEVCONF_MAX_ADDRESSES] = cnf->max_addresses;
 	array[DEVCONF_ACCEPT_RA_DEFRTR] = cnf->accept_ra_defrtr;
+	array[DEVCONF_ACCEPT_RA_DEFRTR_TABLE] = cnf->accept_ra_defrtr_table;
 	array[DEVCONF_ACCEPT_RA_PINFO] = cnf->accept_ra_pinfo;
 #ifdef CONFIG_IPV6_ROUTER_PREF
 	array[DEVCONF_ACCEPT_RA_RTR_PREF] = cnf->accept_ra_rtr_pref;

@@ -4496,6 +4499,13 @@ static struct addrconf_sysctl_table
 			.proc_handler	= proc_dointvec,
 		},
 		{
+			.procname	= "accept_ra_defrtr_table",
+			.data		= &ipv6_devconf.accept_ra_defrtr_table,
+			.maxlen		= sizeof(int),
+			.mode		= 0644,
+			.proc_handler	= proc_dointvec,
+		},
+		{
 			.procname	= "accept_ra_pinfo",
 			.data		= &ipv6_devconf.accept_ra_pinfo,
 			.maxlen		= sizeof(int),
net/ipv6/route.c +31 -14

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