Commit 5b18f128 authored by Stephen Suryaputra's avatar Stephen Suryaputra Committed by David S. Miller
Browse files

ipv4: reset rt_iif for recirculated mcast/bcast out pkts 



Multicast or broadcast egress packets have rt_iif set to the oif. These
packets might be recirculated back as input and lookup to the raw
sockets may fail because they are bound to the incoming interface
(skb_iif). If rt_iif is not zero, during the lookup, inet_iif() function
returns rt_iif instead of skb_iif. Hence, the lookup fails.

v2: Make it non vrf specific (David Ahern). Reword the changelog to
    reflect it.
Signed-off-by: default avatarStephen Suryaputra <ssuryaextr@gmail.com>
Reviewed-by: default avatarDavid Ahern <dsahern@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ee429742

include/net/route.h

+1 −0
Original line number Diff line number Diff line
@@ -221,6 +221,7 @@ void ip_rt_get_source(u8 *src, struct sk_buff *skb, struct rtable *rt); 
struct rtable *rt_dst_alloc(struct net_device *dev,

			     unsigned int flags, u16 type,

			     bool nopolicy, bool noxfrm, bool will_cache);

struct rtable *rt_dst_clone(struct net_device *dev, struct rtable *rt);



struct in_ifaddr;

void fib_add_ifaddr(struct in_ifaddr *);

net/ipv4/ip_output.c

+12 −0
Original line number Diff line number Diff line
@@ -318,6 +318,7 @@ static int ip_finish_output(struct net *net, struct sock *sk, struct sk_buff *sk 
static int ip_mc_finish_output(struct net *net, struct sock *sk,

			       struct sk_buff *skb)

{

	struct rtable *new_rt;

	int ret;



	ret = BPF_CGROUP_RUN_PROG_INET_EGRESS(sk, skb);
@@ -326,6 +327,17 @@ static int ip_mc_finish_output(struct net *net, struct sock *sk, 
		return ret;

	}



	/* Reset rt_iif so that inet_iif() will return skb->skb_iif. Setting

	 * this to non-zero causes ipi_ifindex in in_pktinfo to be overwritten,

	 * see ipv4_pktinfo_prepare().

	 */

	new_rt = rt_dst_clone(net->loopback_dev, skb_rtable(skb));

	if (new_rt) {

		new_rt->rt_iif = 0;

		skb_dst_drop(skb);

		skb_dst_set(skb, &new_rt->dst);

	}



	return dev_loopback_xmit(net, sk, skb);

}

net/ipv4/route.c

+33 −0
Original line number Diff line number Diff line
@@ -1647,6 +1647,39 @@ struct rtable *rt_dst_alloc(struct net_device *dev, 
}

EXPORT_SYMBOL(rt_dst_alloc);



struct rtable *rt_dst_clone(struct net_device *dev, struct rtable *rt)

{

	struct rtable *new_rt;



	new_rt = dst_alloc(&ipv4_dst_ops, dev, 1, DST_OBSOLETE_FORCE_CHK,

			   rt->dst.flags);



	if (new_rt) {

		new_rt->rt_genid = rt_genid_ipv4(dev_net(dev));

		new_rt->rt_flags = rt->rt_flags;

		new_rt->rt_type = rt->rt_type;

		new_rt->rt_is_input = rt->rt_is_input;

		new_rt->rt_iif = rt->rt_iif;

		new_rt->rt_pmtu = rt->rt_pmtu;

		new_rt->rt_mtu_locked = rt->rt_mtu_locked;

		new_rt->rt_gw_family = rt->rt_gw_family;

		if (rt->rt_gw_family == AF_INET)

			new_rt->rt_gw4 = rt->rt_gw4;

		else if (rt->rt_gw_family == AF_INET6)

			new_rt->rt_gw6 = rt->rt_gw6;

		INIT_LIST_HEAD(&new_rt->rt_uncached);



		new_rt->dst.flags |= DST_HOST;

		new_rt->dst.input = rt->dst.input;

		new_rt->dst.output = rt->dst.output;

		new_rt->dst.error = rt->dst.error;

		new_rt->dst.lastuse = jiffies;

		new_rt->dst.lwtstate = lwtstate_get(rt->dst.lwtstate);

	}

	return new_rt;

}

EXPORT_SYMBOL(rt_dst_clone);



/* called in rcu_read_lock() section */

int ip_mc_validate_source(struct sk_buff *skb, __be32 daddr, __be32 saddr,

			  u8 tos, struct net_device *dev,

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