netdev - Re: [PATCH net v2] net: ipmr: Fix some mroute forwarding issues in vrf's

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Date:   Fri, 9 Jun 2017 11:20:11 -0400
From:   Donald Sharp <sharpd@...ulusnetworks.com>
To:     David Ahern <dsahern@...il.com>
Cc:     netdev@...r.kernel.org,
        Thomas Winter <Thomas.Winter@...iedtelesis.co.nz>,
        Nikolay Aleksandrov <nikolay@...ulusnetworks.com>,
        Yotam Gigi <yotamg@...lanox.com>,
        Ido Schimmel <idosch@...lanox.com>,
        Roopa Prabhu <roopa@...ulusnetworks.com>
Subject: Re: [PATCH net v2] net: ipmr: Fix some mroute forwarding issues in vrf's

I'll change it over to this way.  No problem.

donald

On Fri, Jun 9, 2017 at 10:54 AM, David Ahern <dsahern@...il.com> wrote:
> On 6/9/17 8:22 AM, Donald Sharp wrote:
>> @@ -988,7 +988,16 @@ 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);
>> +                        struct net_device *dev = skb->dev;
>> +
>> +                        if (netif_is_l3_master(dev)) {
>> +                                dev = __dev_get_by_index(net, IPCB(skb)->iif);
>> +                                if (!dev) {
>> +                                        kfree_skb(skb);
>> +                                        continue;
>> +                                }
>> +                        }
>> +                        ip_mr_forward(net, mrt, dev, skb, c, 0);
>>               }
>>       }
>>  }
>
> What about changing ipmr_cache_unresolved to take the dev it looked up
> already and then have ipmr_cache_unresolved reset skb->dev to it (and
> reset skb->skb_iff to dev->ifindex) when queuing to the unresolved list?
> Since this path does not have a local delivery, resetting the skb->dev
> will be fine and it avoids this second lookup using IPCB(skb)->iif:
>
> @@ -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;
>         }
>
>
> Combined with Thomas' earlier change this check in ip_mr_forward becomes:
>
> diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
> index 9374b99c7c17..1393a4d18a9a 100644
> --- a/net/ipv4/ipmr.c
> +++ b/net/ipv4/ipmr.c
> @@ -1853,13 +1853,7 @@ 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...