Re: [PATCH] IPv6 : add multicast routing verify which net_device is lo

[Wang Xingtong <wangxingtong@cn.fujitsu.com>]

Wang Xingtong 写道:
> In currently routing subsystem, when we lookup a multicast routing
> to send muticast packets to outside, rt6_device_match will return
> the rt6_info which it's match first. if we add a multicast route on
> loopback devices beforce the others interface, rt6_device_match will
> retrun the rt6_info which rt6i_dev->name is "lo". But, obviously,
> we can't send a muticast packet to outside using loopback devices.
> It case all multicast packets blocking.
> 
> Commit 4af04aba93f47699e disabled kernel add multicast route on lo
> automatically. However,  we can't surmise the routing-add order or
> interdict add multicast routing on loopback devices in user space.
> The bug still exist. So, i think more stronger routing subsystem is
> necessary.

sorry, the patch has some problem , i will send V2 later.

> 
> Signed-off-by: Wang xingtong <wangxingtong@cn.fujitsu.com>
> 
> ---
>  net/ipv6/route.c |   19 ++++++++++++++++---
>  1 files changed, 16 insertions(+), 3 deletions(-)
> 
> diff --git a/net/ipv6/route.c b/net/ipv6/route.c
> index b582a0a..3871ef4 100644
> --- a/net/ipv6/route.c
> +++ b/net/ipv6/route.c
> @@ -334,9 +334,16 @@ static inline struct rt6_info 
> *rt6_device_match(struct net *net,
>      struct rt6_info *local = NULL;
>      struct rt6_info *sprt;
> 
> -    if (!oif && ipv6_addr_any(saddr))
> +    if (!oif && ipv6_addr_any(saddr)){
> +        if (unlikely(rt->rt6i_dev->flags & IFF_LOOPBACK &&
> +            ipv6_addr_is_multicast(&rt->rt6i_dst.addr))){
> +            rt=rt->dst.rt6_next;
> +            goto match;
> +        }
>          goto out;
> +    }
> 
> +match:
>      for (sprt = rt; sprt; sprt = sprt->dst.rt6_next) {
>          struct net_device *dev = sprt->rt6i_dev;
> 
> @@ -355,9 +362,15 @@ static inline struct rt6_info 
> *rt6_device_match(struct net *net,
>                  local = sprt;
>              }
>          } else {
> -            if (ipv6_chk_addr(net, saddr, dev,
> -                      flags & RT6_LOOKUP_F_IFACE))
> +            if (ipv6_addr_any(saddr)){
> +                if (unlikely(rt->rt6i_dev->flags & IFF_LOOPBACK &&
> +                    ipv6_addr_is_multicast(&rt->rt6i_dst.addr))){
> +                    continue;
>                  return sprt;
> +            }
> +            else if (ipv6_chk_addr(net, saddr, dev,
> +                      flags & RT6_LOOKUP_F_IFACE))
> +                    return sprt;
>          }
>      }
>