netdev - Re: [PATCH net v3] net: ipmr: Fix some mroute forwarding issues in vrf's

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Date:   Sun, 11 Jun 2017 09:12:47 +0300
From:   Yotam Gigi <yotamg@...lanox.com>
To:     Donald Sharp <sharpd@...ulusnetworks.com>, netdev@...r.kernel.org,
        dsahern@...il.com, Thomas.Winter@...iedtelesis.co.nz,
        nikolay@...ulusnetworks.com, idosch@...lanox.com,
        roopa@...ulusnetworks.com
Subject: Re: [PATCH net v3] net: ipmr: Fix some mroute forwarding issues in
 vrf's

On 06/10/2017 11:30 PM, Donald Sharp wrote:
> This patch fixes two issues:
>
> 1) When forwarding on *,G mroutes that are in a vrf, the
> kernel was dropping information about the actual incoming
> interface when calling ip_mr_forward from ip_mr_input.
> This caused ip_mr_forward to send the multicast packet
> back out the incoming interface.  Fix this by
> modifying ip_mr_forward to be handed the correctly
> resolved dev.
>
> 2) When a unresolved cache entry is created we store
> the incoming skb on the unresolved cache entry and
> upon mroute resolution from the user space daemon,
> we attempt to forward the packet.  Again we were
> not resolving to the correct incoming device for
> a vrf scenario, before calling ip_mr_forward.
> Fix this by resolving to the correct interface
> and calling ip_mr_forward with the result.
>
> Fixes: e58e41596811 ("net: Enable support for VRF with ipv4 multicast")
> Signed-off-by: Donald Sharp <sharpd@...ulusnetworks.com>
> ---
> v2: Fixed title
> v3: Addressed Review comments by Andrew Lunn and David Ahern
>
>  net/ipv4/ipmr.c | 32 +++++++++++++++-----------------
>  1 file changed, 15 insertions(+), 17 deletions(-)
>
> diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
> index 551de4d..09368a1 100644
> --- a/net/ipv4/ipmr.c
> +++ b/net/ipv4/ipmr.c
> @@ -101,8 +101,8 @@ static struct mr_table *ipmr_new_table(struct net *net, u32 id);
>  static void ipmr_free_table(struct mr_table *mrt);
>  
>  static void ip_mr_forward(struct net *net, struct mr_table *mrt,
> -			  struct sk_buff *skb, struct mfc_cache *cache,
> -			  int local);
> +			  struct net_device *dev, struct sk_buff *skb,
> +			  struct mfc_cache *cache, int local);
>  static int ipmr_cache_report(struct mr_table *mrt,
>  			     struct sk_buff *pkt, vifi_t vifi, int assert);
>  static int __ipmr_fill_mroute(struct mr_table *mrt, struct sk_buff *skb,
> @@ -988,7 +988,7 @@ static void ipmr_cache_resolve(struct net *net, struct mr_table *mrt,
>  
>  			rtnl_unicast(skb, net, NETLINK_CB(skb).portid);
>  		} else {
> -			ip_mr_forward(net, mrt, skb, c, 0);
> +			ip_mr_forward(net, mrt, skb->dev, skb, c, 0);
>  		}
>  	}
>  }
> @@ -1073,7 +1073,7 @@ static int ipmr_cache_report(struct mr_table *mrt,
>  
>  /* Queue a packet for resolution. It gets locked cache entry! */
>  static int ipmr_cache_unresolved(struct mr_table *mrt, vifi_t vifi,
> -				 struct sk_buff *skb)
> +				 struct sk_buff *skb, struct net_device *dev)
>  {
>  	const struct iphdr *iph = ip_hdr(skb);
>  	struct mfc_cache *c;
> @@ -1130,6 +1130,10 @@ static int ipmr_cache_unresolved(struct mr_table *mrt, vifi_t vifi,
>  		kfree_skb(skb);
>  		err = -ENOBUFS;
>  	} else {
> +		if (dev) {
> +			skb->dev = dev;
> +			skb->skb_iif = dev->ifindex;
> +		}
>  		skb_queue_tail(&c->mfc_un.unres.unresolved, skb);
>  		err = 0;
>  	}
> @@ -1828,10 +1832,10 @@ static int ipmr_find_vif(struct mr_table *mrt, struct net_device *dev)
>  
>  /* "local" means that we should preserve one skb (for local delivery) */
>  static void ip_mr_forward(struct net *net, struct mr_table *mrt,
> -			  struct sk_buff *skb, struct mfc_cache *cache,
> -			  int local)
> +			  struct net_device *dev, struct sk_buff *skb,
> +			  struct mfc_cache *cache, int local)
>  {
> -	int true_vifi = ipmr_find_vif(mrt, skb->dev);
> +	int true_vifi = ipmr_find_vif(mrt, dev);
>  	int psend = -1;
>  	int vif, ct;
>  
> @@ -1853,13 +1857,7 @@ static void ip_mr_forward(struct net *net, struct mr_table *mrt,
>  	}
>  
>  	/* Wrong interface: drop packet and (maybe) send PIM assert. */
> -	if (mrt->vif_table[vif].dev != skb->dev) {
> -		struct net_device *mdev;
> -
> -		mdev = l3mdev_master_dev_rcu(mrt->vif_table[vif].dev);
> -		if (mdev == skb->dev)
> -			goto forward;
> -
> +	if (mrt->vif_table[vif].dev != dev) {
>  		if (rt_is_output_route(skb_rtable(skb))) {
>  			/* It is our own packet, looped back.
>  			 * Very complicated situation...
> @@ -2053,7 +2051,7 @@ int ip_mr_input(struct sk_buff *skb)
>  		read_lock(&mrt_lock);
>  		vif = ipmr_find_vif(mrt, dev);
>  		if (vif >= 0) {
> -			int err2 = ipmr_cache_unresolved(mrt, vif, skb);
> +			int err2 = ipmr_cache_unresolved(mrt, vif, skb, dev);
>  			read_unlock(&mrt_lock);
>  
>  			return err2;
> @@ -2064,7 +2062,7 @@ int ip_mr_input(struct sk_buff *skb)
>  	}
>  
>  	read_lock(&mrt_lock);
> -	ip_mr_forward(net, mrt, skb, cache, local);
> +	ip_mr_forward(net, mrt, dev, skb, cache, local);
>  	read_unlock(&mrt_lock);
>  
>  	if (local)
> @@ -2238,7 +2236,7 @@ int ipmr_get_route(struct net *net, struct sk_buff *skb,
>  		iph->saddr = saddr;
>  		iph->daddr = daddr;
>  		iph->version = 0;
> -		err = ipmr_cache_unresolved(mrt, vif, skb2);
> +		err = ipmr_cache_unresolved(mrt, vif, skb2, dev);
>  		read_unlock(&mrt_lock);
>  		rcu_read_unlock();
>  		return err;

Thanks Donald!

Reviewed-by: Yotam Gigi <yotamg@...lanox.com>