Patch "ipv6: set rt6i_protocol properly in the route when it is installed" has been added to the 4.12-stable tree

This is a note to let you know that I've just added the patch titled

ipv6: set rt6i_protocol properly in the route when it is installed

to the 4.12-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
ipv6-set-rt6i_protocol-properly-in-the-route-when-it-is-installed.patch
and it can be found in the queue-4.12 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Xin Long <[email protected]>
Date: Thu, 3 Aug 2017 14:13:46 +0800
Subject: ipv6: set rt6i_protocol properly in the route when it is installed

From: Xin Long <[email protected]>

[ Upstream commit b91d532928dff2141ea9c107c3e73104d9843767 ]

After commit c2ed1880fd61 ("net: ipv6: check route protocol when deleting routes"), ipv6 route checks rt protocol when trying to remove a rt entry.

It introduced a side effect causing 'ip -6 route flush cache' not to work well. When flushing caches with iproute, all route caches get dumped from kernel then removed one by one by sending DELROUTE requests to kernel for each cache.

The thing is iproute sends the request with the cache whose proto is set with RTPROT_REDIRECT by rt6_fill_node() when kernel dumps it. But in kernel the rt_cache protocol is still 0, which causes the cache not to be matched and removed.

So the real reason is rt6i_protocol in the route is not set when it is allocated. As David Ahern's suggestion, this patch is to set rt6i_protocol properly in the route when it is installed and remove the codes setting rtm_protocol according to rt6i_flags in rt6_fill_node.

This is also an improvement to keep rt6i_protocol consistent with rtm_protocol.

---
 net/ipv6/route.c |   11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

@@ -2366,6 +2366,7 @@ static void rt6_do_redirect(struct dst_e
 	if (on_link)
 		nrt->rt6i_flags &= ~RTF_GATEWAY;
 
+	nrt->rt6i_protocol = RTPROT_REDIRECT;
 	nrt->rt6i_gateway = *(struct in6_addr *)neigh->primary_key;
 
 	if (ip6_ins_rt(nrt))

@@ -2470,6 +2471,7 @@ static struct rt6_info *rt6_add_route_in
 		.fc_dst_len	= prefixlen,
 		.fc_flags	= RTF_GATEWAY | RTF_ADDRCONF | RTF_ROUTEINFO |
 				  RTF_UP | RTF_PREF(pref),
+		.fc_protocol = RTPROT_RA,
 		.fc_nlinfo.portid = 0,
 		.fc_nlinfo.nlh = NULL,
 		.fc_nlinfo.nl_net = net,

@@ -2522,6 +2524,7 @@ struct rt6_info *rt6_add_dflt_router(con
 		.fc_ifindex	= dev->ifindex,
 		.fc_flags	= RTF_GATEWAY | RTF_ADDRCONF | RTF_DEFAULT |
 				  RTF_UP | RTF_EXPIRES | RTF_PREF(pref),
+		.fc_protocol = RTPROT_RA,
 		.fc_nlinfo.portid = 0,
 		.fc_nlinfo.nlh = NULL,
 		.fc_nlinfo.nl_net = dev_net(dev),

@@ -3434,14 +3437,6 @@ static int rt6_fill_node(struct net *net
 	rtm->rtm_flags = 0;
 	rtm->rtm_scope = RT_SCOPE_UNIVERSE;
 	rtm->rtm_protocol = rt->rt6i_protocol;
-	if (rt->rt6i_flags & RTF_DYNAMIC)
-		rtm->rtm_protocol = RTPROT_REDIRECT;
-	else if (rt->rt6i_flags & RTF_ADDRCONF) {
-		if (rt->rt6i_flags & (RTF_DEFAULT | RTF_ROUTEINFO))
-			rtm->rtm_protocol = RTPROT_RA;
-		else
-			rtm->rtm_protocol = RTPROT_KERNEL;
-	}
 
 	if (rt->rt6i_flags & RTF_CACHE)
 		rtm->rtm_flags |= RTM_F_CLONED;

Patches currently in stable-queue which might be from [email protected] are

queue-4.12/ipv6-set-rt6i_protocol-properly-in-the-route-when-it-is-installed.patch queue-4.12/net-sched-set-xt_tgchk_param-par.nft_compat-as-0-in-ipt_init_target.patch queue-4.12/net-sched-set-xt_tgchk_param-par.net-properly-in-ipt_init_target.patch