[PATCH net-next 0/2] Put ip6_fragment in ipv6_stub

[PATCH net-next 0/2] Put ip6_fragment in ipv6_stub

[wenxu]

From: wenxu <wenxu@ucloud.cn>

Add ip6_fragment in ipv6_stub and use it in openvswitch

wenxu (2):
  ipv6: add ipv6_fragment hook in ipv6_stub
  openvswitch: using ip6_fragment in ipv6_stub

 include/net/ipv6_stubs.h  | 2 ++
 net/ipv6/af_inet6.c       | 1 +
 net/openvswitch/actions.c | 6 ++----
 3 files changed, 5 insertions(+), 4 deletions(-)

-- 
1.8.3.1

[PATCH net-next 1/2] ipv6: add ipv6_fragment hook in ipv6_stub

[wenxu]

From: wenxu <wenxu@ucloud.cn>

Add ipv6_fragment to ipv6_stub to avoid calling netfilter when
access ip6_fragment.

Signed-off-by: wenxu <wenxu@ucloud.cn>
---
 include/net/ipv6_stubs.h | 3 +++
 net/ipv6/af_inet6.c      | 1 +
 2 files changed, 4 insertions(+)

diff --git a/include/net/ipv6_stubs.h b/include/net/ipv6_stubs.h
index d7a7f7c..8fce558 100644
--- a/include/net/ipv6_stubs.h
+++ b/include/net/ipv6_stubs.h
@@ -63,6 +63,9 @@ struct ipv6_stub {
 			       int encap_type);
 #endif
 	struct neigh_table *nd_tbl;
+
+	int (*ipv6_fragment)(struct net *net, struct sock *sk, struct sk_buff *skb,
+			     int (*output)(struct net *, struct sock *, struct sk_buff *));
 };
 extern const struct ipv6_stub *ipv6_stub __read_mostly;
 
diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index d9a1493..e648fbe 100644
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -1027,6 +1027,7 @@ static int ipv6_route_input(struct sk_buff *skb)
 	.xfrm6_rcv_encap = xfrm6_rcv_encap,
 #endif
 	.nd_tbl	= &nd_tbl,
+	.ipv6_fragment = ip6_fragment,
 };
 
 static const struct ipv6_bpf_stub ipv6_bpf_stub_impl = {
-- 
1.8.3.1

[PATCH net-next 2/2] openvswitch: using ip6_fragment in ipv6_stub

[wenxu]

From: wenxu <wenxu@ucloud.cn>

Using ipv6_stub->ipv6_fragment to avoid the netfilter dependency

Signed-off-by: wenxu <wenxu@ucloud.cn>
---
 net/openvswitch/actions.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c
index 2611657..1f3d406 100644
--- a/net/openvswitch/actions.c
+++ b/net/openvswitch/actions.c
@@ -9,7 +9,6 @@
 #include <linux/in.h>
 #include <linux/ip.h>
 #include <linux/openvswitch.h>
-#include <linux/netfilter_ipv6.h>
 #include <linux/sctp.h>
 #include <linux/tcp.h>
 #include <linux/udp.h>
@@ -848,11 +847,10 @@ static void ovs_fragment(struct net *net, struct vport *vport,
 		ip_do_fragment(net, skb->sk, skb, ovs_vport_output);
 		refdst_drop(orig_dst);
 	} else if (key->eth.type == htons(ETH_P_IPV6)) {
-		const struct nf_ipv6_ops *v6ops = nf_get_ipv6_ops();
 		unsigned long orig_dst;
 		struct rt6_info ovs_rt;
 
-		if (!v6ops)
+		if (!ipv6_stub->ipv6_fragment)
 			goto err;
 
 		prepare_frag(vport, skb, orig_network_offset,
@@ -866,7 +864,7 @@ static void ovs_fragment(struct net *net, struct vport *vport,
 		skb_dst_set_noref(skb, &ovs_rt.dst);
 		IP6CB(skb)->frag_max_size = mru;
 
-		v6ops->fragment(net, skb->sk, skb, ovs_vport_output);
+		ipv6_stub->ipv6_fragment(net, skb->sk, skb, ovs_vport_output);
 		refdst_drop(orig_dst);
 	} else {
 		WARN_ONCE(1, "Failed fragment ->%s: eth=%04x, MRU=%d, MTU=%d.",
-- 
1.8.3.1

Re: [PATCH net-next 1/2] ipv6: add ipv6_fragment hook in ipv6_stub

[David Miller]

From: wenxu@ucloud.cn
Date: Thu, 27 Aug 2020 18:39:51 +0800

> From: wenxu <wenxu@ucloud.cn>
> 
> Add ipv6_fragment to ipv6_stub to avoid calling netfilter when
> access ip6_fragment.
> 
> Signed-off-by: wenxu <wenxu@ucloud.cn>

Please test these changes with ipv6 disabled.

It will crash, you have to update the default stub in
net/ipv6/addrconf_core.c as well.

Re: [PATCH net-next 1/2] ipv6: add ipv6_fragment hook in ipv6_stub

[Marcelo Ricardo Leitner]

On Thu, Aug 27, 2020 at 07:51:47AM -0700, David Miller wrote:
> From: wenxu@ucloud.cn
> Date: Thu, 27 Aug 2020 18:39:51 +0800
> 
> > From: wenxu <wenxu@ucloud.cn>
> > 
> > Add ipv6_fragment to ipv6_stub to avoid calling netfilter when
> > access ip6_fragment.
> > 
> > Signed-off-by: wenxu <wenxu@ucloud.cn>
> 
> Please test these changes with ipv6 disabled.
> 
> It will crash, you have to update the default stub in
> net/ipv6/addrconf_core.c as well.

I didn't test it myself but I'm not seeing how the crash could happen.
The next patch does check for it being NULL before using it:

-               if (!v6ops)
+               if (!ipv6_stub->ipv6_fragment)
                        goto err;

Wenxu?

  Marcelo

Re: [PATCH net-next 1/2] ipv6: add ipv6_fragment hook in ipv6_stub

[wenxu]

Yes， I check the ipv6_stub->ipv6_fragment. And in the case

if there is no ipv6_stub->ipv6_fragment it means no ipv6 fragment support

and it should free the skb.

Maybe sometimes  not all the calling remember to check with this? So

it should add a default one with following?

+static int eafnosupport_ipv6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
+                                     int (*output)(struct net *, struct sock *, struct sk_buff *))
+{
+       kfree_skb(skb);
+       return -EAFNOSUPPORT;
+}
+

在 2020/8/28 6:38, Marcelo Ricardo Leitner 写道:
> On Thu, Aug 27, 2020 at 07:51:47AM -0700, David Miller wrote:
>> From: wenxu@ucloud.cn
>> Date: Thu, 27 Aug 2020 18:39:51 +0800
>>
>>> From: wenxu <wenxu@ucloud.cn>
>>>
>>> Add ipv6_fragment to ipv6_stub to avoid calling netfilter when
>>> access ip6_fragment.
>>>
>>> Signed-off-by: wenxu <wenxu@ucloud.cn>
>> Please test these changes with ipv6 disabled.
>>
>> It will crash, you have to update the default stub in
>> net/ipv6/addrconf_core.c as well.
> I didn't test it myself but I'm not seeing how the crash could happen.
> The next patch does check for it being NULL before using it:
>
> -               if (!v6ops)
> +               if (!ipv6_stub->ipv6_fragment)
>                         goto err;
>
> Wenxu?
>
>   Marcelo
>