Commit 5be083ce authored by David Ahern's avatar David Ahern Committed by David S. Miller
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net: ipv6: Remove redundant RTA_OIF in multipath routes 



Dinesh reported that RTA_MULTIPATH nexthops are 8-bytes larger with IPv6
than IPv4. The recent refactoring for multipath support in netlink
messages does discriminate between non-multipath which needs the OIF
and multipath which adds a rtnexthop struct for each hop making the
RTA_OIF attribute redundant. Resolve by adding a flag to the info
function to skip the oif for multipath.

Fixes: beb1afac ("net: ipv6: Add support to dump multipath routes
       via RTA_MULTIPATH attribute")
Reported-by: default avatarDinesh Dutt <ddutt@cumulusnetworks.com>
Signed-off-by: default avatarDavid Ahern <dsa@cumulusnetworks.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 713c43b3

net/ipv6/route.c

+6 −5
Original line number Diff line number Diff line
@@ -3299,7 +3299,6 @@ static size_t rt6_nlmsg_size(struct rt6_info *rt) 
		nexthop_len = nla_total_size(0)	 /* RTA_MULTIPATH */

			    + NLA_ALIGN(sizeof(struct rtnexthop))

			    + nla_total_size(16) /* RTA_GATEWAY */

			    + nla_total_size(4)  /* RTA_OIF */

			    + lwtunnel_get_encap_size(rt->dst.lwtstate);



		nexthop_len *= rt->rt6i_nsiblings;
@@ -3323,7 +3322,7 @@ static size_t rt6_nlmsg_size(struct rt6_info *rt) 
}



static int rt6_nexthop_info(struct sk_buff *skb, struct rt6_info *rt,

			    unsigned int *flags)

			    unsigned int *flags, bool skip_oif)

{

	if (!netif_running(rt->dst.dev) || !netif_carrier_ok(rt->dst.dev)) {

		*flags |= RTNH_F_LINKDOWN;
@@ -3336,7 +3335,8 @@ static int rt6_nexthop_info(struct sk_buff *skb, struct rt6_info *rt, 
			goto nla_put_failure;

	}



	if (rt->dst.dev &&

	/* not needed for multipath encoding b/c it has a rtnexthop struct */

	if (!skip_oif && rt->dst.dev &&

	    nla_put_u32(skb, RTA_OIF, rt->dst.dev->ifindex))

		goto nla_put_failure;
@@ -3350,6 +3350,7 @@ nla_put_failure: 
	return -EMSGSIZE;

}



/* add multipath next hop */

static int rt6_add_nexthop(struct sk_buff *skb, struct rt6_info *rt)

{

	struct rtnexthop *rtnh;
@@ -3362,7 +3363,7 @@ static int rt6_add_nexthop(struct sk_buff *skb, struct rt6_info *rt) 
	rtnh->rtnh_hops = 0;

	rtnh->rtnh_ifindex = rt->dst.dev ? rt->dst.dev->ifindex : 0;



	if (rt6_nexthop_info(skb, rt, &flags) < 0)

	if (rt6_nexthop_info(skb, rt, &flags, true) < 0)

		goto nla_put_failure;



	rtnh->rtnh_flags = flags;
@@ -3515,7 +3516,7 @@ static int rt6_fill_node(struct net *net, 


		nla_nest_end(skb, mp);

	} else {

		if (rt6_nexthop_info(skb, rt, &rtm->rtm_flags) < 0)

		if (rt6_nexthop_info(skb, rt, &rtm->rtm_flags, false) < 0)

			goto nla_put_failure;

	}

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