On 2/28/17 11:48 AM, Cong Wang wrote:
> On Tue, Feb 28, 2017 at 11:01 AM, David Ahern <d...@cumulusnetworks.com>
> wrote:
>> On 2/28/17 10:44 AM, Cong Wang wrote:
>>> Like commit 1f17e2f2c8a8 ("net: ipv6: ignore null_entry on route dumps"),
>>> we need to ignore null entry in inet6_rtm_getroute() too.
>>>
>>> Return -ENOENT here because we return the same errno when deleting
>>> the null entry.
>>>
>>> Fixes: a1a22c1206 ("net: ipv6: Keep nexthop of multipath route on admin
>>> down")
>>> Reported-by: Dmitry Vyukov <dvyu...@google.com>
>>> Cc: David Ahern <d...@cumulusnetworks.com>
>>> Signed-off-by: Cong Wang <xiyou.wangc...@gmail.com>
>>> ---
>>> net/ipv6/route.c | 6 ++++++
>>> 1 file changed, 6 insertions(+)
>>>
>>> diff --git a/net/ipv6/route.c b/net/ipv6/route.c
>>> index f54f426..25590d1 100644
>>> --- a/net/ipv6/route.c
>>> +++ b/net/ipv6/route.c
>>> @@ -3627,6 +3627,12 @@ static int inet6_rtm_getroute(struct sk_buff
>>> *in_skb, struct nlmsghdr *nlh)
>>> rt = (struct rt6_info *)ip6_route_output(net, NULL, &fl6);
>>> }
>>>
>>> + if (rt == net->ipv6.ip6_null_entry) {
>>> + ip6_rt_put(rt);
>>> + err = -ENOENT;
>>> + goto errout;
>>> + }
>>> +
>>> skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
>>> if (!skb) {
>>> ip6_rt_put(rt);
>>>
>>
>> hold on. That test exposed something else, not just a getroute problem.
>> I accidentally ran 'unsahre -n; ip -6 ro ls' on my host machine instead
>> of a VM, so took some time to recover. dumproute already covers the null
>> route.
My host was running a slightly older kernel (did not have the null_entry
check in the dump route path for one).
As for trapping null_entry on getroute, this changes user experience.
Right now you always get a route response for IPv6 with the error set as
rta_error. This patch changes that. I am fine with it since it makes
IPv6 more like IPv4:
# ip -6 ro get 2001:db8:12::1
RTNETLINK answers: Network is unreachable
But, if we are going to do this then err should be set based on
rt->dst.error (ENOENT is not the right error) and the commit message
should state the change.
