[net] ipv6: no need to return rt->dst.error if it is not null entry.

After commit 18c3a61c4264 ("net: ipv6: RTM_GETROUTE: return matched fib
result when requested"). When we get a prohibit ertry, we will return
-EACCES directly.

Before:
+ ip netns exec client ip -6 route get 2003::1
prohibit 2003::1 dev lo table unspec proto kernel src 2001::1 metric
4294967295 error -13

After:
+ ip netns exec server ip -6 route get 2002::1
RTNETLINK answers: Network is unreachable

Since we will check the ip6_null_entry later. There is not sense
to check the dst.error after get rt.

Fixes: 18c3a61c4264 ("net: ipv6: RTM_GETROUTE: return matched fib...")
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
---
 net/ipv6/route.c | 6 ------
 1 file changed, 6 deletions(-)

Hi Roopa, Cong,

2017-07-20 22:51 GMT+08:00 Hangbin Liu <liuhangbin@gmail.com>:
> After commit 18c3a61c4264 ("net: ipv6: RTM_GETROUTE: return matched fib
> result when requested"). When we get a prohibit ertry, we will return
> -EACCES directly.
>
> Before:
> + ip netns exec client ip -6 route get 2003::1
> prohibit 2003::1 dev lo table unspec proto kernel src 2001::1 metric
> 4294967295 error -13
>
> After:
> + ip netns exec server ip -6 route get 2002::1
> RTNETLINK answers: Network is unreachable
>
> Since we will check the ip6_null_entry later. There is not sense
> to check the dst.error after get rt.
>
> Fixes: 18c3a61c4264 ("net: ipv6: RTM_GETROUTE: return matched fib...")
> Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
> ---
>  net/ipv6/route.c | 6 ------
>  1 file changed, 6 deletions(-)
>
> diff --git a/net/ipv6/route.c b/net/ipv6/route.c
> index 4d30c96..8fc52de 100644
> --- a/net/ipv6/route.c
> +++ b/net/ipv6/route.c
> @@ -3637,12 +3637,6 @@ static int inet6_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
>                 dst = ip6_route_lookup(net, &fl6, 0);
>
>         rt = container_of(dst, struct rt6_info, dst);
> -       if (rt->dst.error) {
> -               err = rt->dst.error;
> -               ip6_rt_put(rt);
> -               goto errout;
> -       }

hmm... or instead of remove this check, should we check all the entry? Like
if ((rt->dst.error && rt != net->ipv6.ip6_null_entry && rt !=
net->ipv6.ip6_blk_hole_entry) ||
     rt == net->ipv6.ip6_null_entry )

What do you think?

Thanks
Hangbin

On Thu, Jul 20, 2017 at 7:51 AM, Hangbin Liu <liuhangbin@gmail.com> wrote:
> After commit 18c3a61c4264 ("net: ipv6: RTM_GETROUTE: return matched fib
> result when requested"). When we get a prohibit ertry, we will return
> -EACCES directly.
>
> Before:
> + ip netns exec client ip -6 route get 2003::1
> prohibit 2003::1 dev lo table unspec proto kernel src 2001::1 metric
> 4294967295 error -13
>
> After:
> + ip netns exec server ip -6 route get 2002::1
> RTNETLINK answers: Network is unreachable
>
> Since we will check the ip6_null_entry later. There is not sense
> to check the dst.error after get rt.
>
> Fixes: 18c3a61c4264 ("net: ipv6: RTM_GETROUTE: return matched fib...")
> Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
> ---

Acked-by: Roopa Prabhu <roopa@cumulusnetworks.com>


thanks.

Hi Roopa,
On Sat, Jul 22, 2017 at 09:55:51PM -0700, Roopa Prabhu wrote:
> On Thu, Jul 20, 2017 at 7:51 AM, Hangbin Liu <liuhangbin@gmail.com> wrote:
> > After commit 18c3a61c4264 ("net: ipv6: RTM_GETROUTE: return matched fib
> > result when requested"). When we get a prohibit ertry, we will return
> > -EACCES directly.
> >
> > Before:
> > + ip netns exec client ip -6 route get 2003::1
> > prohibit 2003::1 dev lo table unspec proto kernel src 2001::1 metric
> > 4294967295 error -13
> >
> > After:
> > + ip netns exec server ip -6 route get 2002::1
> > RTNETLINK answers: Network is unreachable

Sorry, I have a copy/paste error here, the return error should be

+ ip netns exec server ip -6 route get 2002::1
RTNETLINK answers: Permission denied

I fixed it in v2 patch, but forgot to add
#ifdef CONFIG_IPV6_MULTIPLE_TABLES before net->ipv6.ip6_prohibit_entry.

Since you acked this patch. I will post a v3 patch with fixed comment.

> >
> > Since we will check the ip6_null_entry later. There is not sense
> > to check the dst.error after get rt.
> >
> > Fixes: 18c3a61c4264 ("net: ipv6: RTM_GETROUTE: return matched fib...")
> > Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
> > ---
> 
> Acked-by: Roopa Prabhu <roopa@cumulusnetworks.com>

Thanks
Hangbin