[PATCH] ipv6: send NEWLINK on RA managed/otherconf changes

[PATCH] ipv6: send NEWLINK on RA managed/otherconf changes

[Marius Tomaschewski]

The kernel is applying the RA managed/otherconf flags silently and
forgets to send ifinfo notify to inform about their change when the
router provides a zero reachable_time and retrans_timer as dnsmasq
and many routers send it, which just means unspecified by this router
and the host should continue using whatever value it is already using.
Userspace may monitor the ifinfo notifications to activate dhcpv6.

Signed-off-by: Marius Tomaschewski <mt@suse.de>

diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
index c53331c..99ea9dd 100644
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -1074,6 +1074,7 @@ static void ndisc_router_discovery(struct sk_buff *skb)
 	struct ndisc_options ndopts;
 	int optlen;
 	unsigned int pref = 0;
+	__u32 old_if_flags;
 
 	__u8 *opt = (__u8 *)(ra_msg + 1);
 
@@ -1144,6 +1145,7 @@ static void ndisc_router_discovery(struct sk_buff *skb)
 	 * Remember the managed/otherconf flags from most recently
 	 * received RA message (RFC 2462) -- yoshfuji
 	 */
+	old_if_flags = in6_dev->if_flags;
 	in6_dev->if_flags = (in6_dev->if_flags & ~(IF_RA_MANAGED |
 				IF_RA_OTHERCONF)) |
 				(ra_msg->icmph.icmp6_addrconf_managed ?
@@ -1151,6 +1153,9 @@ static void ndisc_router_discovery(struct sk_buff *skb)
 				(ra_msg->icmph.icmp6_addrconf_other ?
 					IF_RA_OTHERCONF : 0);
 
+	if (old_if_flags != in6_dev->if_flags)
+		inet6_ifinfo_notify(RTM_NEWLINK, in6_dev);
+
 	if (!in6_dev->cnf.accept_ra_defrtr) {
 		ND_PRINTK(2, info,
 			  "RA: %s, defrtr is false for dev: %s\n",
-- 
2.1.4

Re: [PATCH] ipv6: send NEWLINK on RA managed/otherconf changes

[David Miller]

From: Marius Tomaschewski <mt@suse.de>
Date: Mon, 31 Aug 2015 15:59:22 +0200

> The kernel is applying the RA managed/otherconf flags silently and
> forgets to send ifinfo notify to inform about their change when the
> router provides a zero reachable_time and retrans_timer as dnsmasq
> and many routers send it, which just means unspecified by this router
> and the host should continue using whatever value it is already using.
> Userspace may monitor the ifinfo notifications to activate dhcpv6.
> 
> Signed-off-by: Marius Tomaschewski <mt@suse.de>

Applied, but more ideally this function should emit only a single
NEWLINK message rather than potentially 3.

Re: [PATCH] ipv6: send NEWLINK on RA managed/otherconf changes

[Marius Tomaschewski]

[-- Attachment #1: Type: text/plain, Size: 1083 bytes --]

Am 01.09.2015 um 00:13 schrieb David Miller:
> From: Marius Tomaschewski <mt@suse.de>
> Date: Mon, 31 Aug 2015 15:59:22 +0200
> 
>> The kernel is applying the RA managed/otherconf flags silently and
>> forgets to send ifinfo notify to inform about their change when the
>> router provides a zero reachable_time and retrans_timer as dnsmasq
>> and many routers send it, which just means unspecified by this router
>> and the host should continue using whatever value it is already using.
>> Userspace may monitor the ifinfo notifications to activate dhcpv6.
>>
>> Signed-off-by: Marius Tomaschewski <mt@suse.de>
> 
> Applied, but more ideally this function should emit only a single
> NEWLINK message rather than potentially 3.

Yes, you're right of course.

I've attached a follow-up patch doing this. Please let me know if you
need it in a separate mail.

Gruesse / Regards,
 Marius Tomaschewski <mt@suse.de>, <mt@suse.com>
-- 
 SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard,
 Dilip Upmanyu, Graham Norton, HRB 21284 (AG Nürnberg),
 Maxfeldstraße 5, 90409 Nürnberg, Germany

[-- Attachment #2: 0002-ipv6-send-only-one-NEWLINK-when-RA-causes-changes.patch --]
[-- Type: text/x-patch, Size: 1622 bytes --]

>From b6b55b5383c9b89cfd5ad9b4584c044c6c8d3722 Mon Sep 17 00:00:00 2001
From: Marius Tomaschewski <mt@suse.de>
Date: Tue, 1 Sep 2015 01:40:57 +0200
Subject: [PATCH] ipv6: send only one NEWLINK when RA causes changes

Signed-off-by: Marius Tomaschewski <mt@suse.de>

diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
index 99ea9dd..7baca60 100644
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -1075,6 +1075,7 @@ static void ndisc_router_discovery(struct sk_buff *skb)
 	int optlen;
 	unsigned int pref = 0;
 	__u32 old_if_flags;
+	int send_ifinfo_notify = 0;
 
 	__u8 *opt = (__u8 *)(ra_msg + 1);
 
@@ -1154,7 +1155,7 @@ static void ndisc_router_discovery(struct sk_buff *skb)
 					IF_RA_OTHERCONF : 0);
 
 	if (old_if_flags != in6_dev->if_flags)
-		inet6_ifinfo_notify(RTM_NEWLINK, in6_dev);
+		send_ifinfo_notify = 1;
 
 	if (!in6_dev->cnf.accept_ra_defrtr) {
 		ND_PRINTK(2, info,
@@ -1259,7 +1260,7 @@ skip_defrtr:
 				rtime = HZ/10;
 			NEIGH_VAR_SET(in6_dev->nd_parms, RETRANS_TIME, rtime);
 			in6_dev->tstamp = jiffies;
-			inet6_ifinfo_notify(RTM_NEWLINK, in6_dev);
+			send_ifinfo_notify = 1;
 		}
 
 		rtime = ntohl(ra_msg->reachable_time);
@@ -1276,11 +1277,17 @@ skip_defrtr:
 					      GC_STALETIME, 3 * rtime);
 				in6_dev->nd_parms->reachable_time = neigh_rand_reach_time(rtime);
 				in6_dev->tstamp = jiffies;
-				inet6_ifinfo_notify(RTM_NEWLINK, in6_dev);
+				send_ifinfo_notify = 1;
 			}
 		}
 	}
 
+	/*
+	 *	Send a notify if RA changed managed/otherconf flags or timer settings
+	 */
+	if (send_ifinfo_notify)
+		inet6_ifinfo_notify(RTM_NEWLINK, in6_dev);
+
 skip_linkparms:
 
 	/*
-- 
2.1.4

Re: [PATCH] ipv6: send NEWLINK on RA managed/otherconf changes

[David Miller]

From: Marius Tomaschewski <mt@suse.de>
Date: Tue, 1 Sep 2015 01:43:39 +0200

> I've attached a follow-up patch doing this. Please let me know if you
> need it in a separate mail.

I want it in a separate mail, and please use "bool" for the type.