[Bridge] [RFC net] bridge: clean the nf_bridge status when forwarding the skb

[Bridge] [RFC net] bridge: clean the nf_bridge status when forwarding the skb

[Antonio Quartulli]

From: Antonio Quartulli <antonio@open-mesh.com>

Even if enslaving a bridge interface into another bridge is
forbidden, it is still possible to create a chain of
virtual interfaces including two distinct bridges.

In this case, the skb entering the second bridge could have
the nf_bridge field already set due to a previous operation
and consequently lead to a wrong processing of the packet
itself.

To prevent this behaviour release and set to NULL the
nf_bridge field of the skb when exiting the bridge interface.

Signed-off-by: Antonio Quartulli <antonio@open-mesh.com>
---

I am not sure if this is a wanted behaviour or a real BUG. I found this
"misbehaviour" while testing batman-adv with the following configuration:

- br0 (bridge interface) having bat0 and eth0 as slaves
- bat0 (which is a virtual interface provided by the batman-adv module and that
  works similarly to a bridge - to some extends) having br1 as slave
- br1 (second bridge interface) having eth1 as slave

Then follow these events:
- a broadcast packet arrives on eth0
- the skb enters br0 and skb->nf_bridge gets initialised and used
- the skb enters bat0 and the packet *gets encapsulated in the batman-adv packet
  which adds a batman-adv header and another Ethernet header*
- the skb enters br1 and gets ruined because nf_bridge_maybe_copy_header() (in
  br_dev_queue_push_xmit()) will try to restore an header that does not make
  sense anymore.

With this patch the nf_bridge gets de-initialised before exiting br0 and
therefore it is processed properly inside br1: nf_bridge_maybe_copy_header()
does not take place at all because nf_bridge is never initialised (the packet is
non-IP since it is a batman-adv packet)

To the developers of the bridge module I would like to ask:
1) is skb->nf_bridge allowed to be non NULL when entering br_dev_xmit() ? If so,
   when is this supposed to happen?

2) do you think this patch is logically correct but the nf_bridge release should
   be done in batman-adv since it is the one re-encapsulating the packet?


I hope I have made the problem clear.

Best regards,


 net/bridge/br_forward.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/net/bridge/br_forward.c b/net/bridge/br_forward.c
index 4b81b14..65864bc 100644
--- a/net/bridge/br_forward.c
+++ b/net/bridge/br_forward.c
@@ -49,6 +49,11 @@ int br_dev_queue_push_xmit(struct sk_buff *skb)
 	} else {
 		skb_push(skb, ETH_HLEN);
 		br_drop_fake_rtable(skb);
+
+		/* clean the NF bridge data */
+		nf_bridge_put(skb->nf_bridge);
+		skb->nf_bridge = NULL;
+
 		dev_queue_xmit(skb);
 	}
 
-- 
1.8.1.5

[RFC net] bridge: clean the nf_bridge status when forwarding the skb

[Antonio Quartulli]

From: Antonio Quartulli <antonio@open-mesh.com>

Even if enslaving a bridge interface into another bridge is
forbidden, it is still possible to create a chain of
virtual interfaces including two distinct bridges.

In this case, the skb entering the second bridge could have
the nf_bridge field already set due to a previous operation
and consequently lead to a wrong processing of the packet
itself.

To prevent this behaviour release and set to NULL the
nf_bridge field of the skb when exiting the bridge interface.

Signed-off-by: Antonio Quartulli <antonio@open-mesh.com>
---

I am not sure if this is a wanted behaviour or a real BUG. I found this
"misbehaviour" while testing batman-adv with the following configuration:

- br0 (bridge interface) having bat0 and eth0 as slaves
- bat0 (which is a virtual interface provided by the batman-adv module and that
  works similarly to a bridge - to some extends) having br1 as slave
- br1 (second bridge interface) having eth1 as slave

Then follow these events:
- a broadcast packet arrives on eth0
- the skb enters br0 and skb->nf_bridge gets initialised and used
- the skb enters bat0 and the packet *gets encapsulated in the batman-adv packet
  which adds a batman-adv header and another Ethernet header*
- the skb enters br1 and gets ruined because nf_bridge_maybe_copy_header() (in
  br_dev_queue_push_xmit()) will try to restore an header that does not make
  sense anymore.

With this patch the nf_bridge gets de-initialised before exiting br0 and
therefore it is processed properly inside br1: nf_bridge_maybe_copy_header()
does not take place at all because nf_bridge is never initialised (the packet is
non-IP since it is a batman-adv packet)

To the developers of the bridge module I would like to ask:
1) is skb->nf_bridge allowed to be non NULL when entering br_dev_xmit() ? If so,
   when is this supposed to happen?

2) do you think this patch is logically correct but the nf_bridge release should
   be done in batman-adv since it is the one re-encapsulating the packet?


I hope I have made the problem clear.

Best regards,


 net/bridge/br_forward.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/net/bridge/br_forward.c b/net/bridge/br_forward.c
index 4b81b14..65864bc 100644
--- a/net/bridge/br_forward.c
+++ b/net/bridge/br_forward.c
@@ -49,6 +49,11 @@ int br_dev_queue_push_xmit(struct sk_buff *skb)
 	} else {
 		skb_push(skb, ETH_HLEN);
 		br_drop_fake_rtable(skb);
+
+		/* clean the NF bridge data */
+		nf_bridge_put(skb->nf_bridge);
+		skb->nf_bridge = NULL;
+
 		dev_queue_xmit(skb);
 	}
 
-- 
1.8.1.5

Re: [Bridge] [RFC net] bridge: clean the nf_bridge status when forwarding the skb

[Stephen Hemminger]

On Thu, 26 Sep 2013 22:19:50 +0200
Antonio Quartulli <antonio@meshcoding.com> wrote:

> From: Antonio Quartulli <antonio@open-mesh.com>
> 
> Even if enslaving a bridge interface into another bridge is
> forbidden, it is still possible to create a chain of
> virtual interfaces including two distinct bridges.
> 
> In this case, the skb entering the second bridge could have
> the nf_bridge field already set due to a previous operation
> and consequently lead to a wrong processing of the packet
> itself.
> 
> To prevent this behaviour release and set to NULL the
> nf_bridge field of the skb when exiting the bridge interface.
> 
> Signed-off-by: Antonio Quartulli <antonio@open-mesh.com>
> ---
> 
> I am not sure if this is a wanted behaviour or a real BUG. I found this
> "misbehaviour" while testing batman-adv with the following configuration:
> 
> - br0 (bridge interface) having bat0 and eth0 as slaves
> - bat0 (which is a virtual interface provided by the batman-adv module and that
>   works similarly to a bridge - to some extends) having br1 as slave
> - br1 (second bridge interface) having eth1 as slave
> 
> Then follow these events:
> - a broadcast packet arrives on eth0
> - the skb enters br0 and skb->nf_bridge gets initialised and used
> - the skb enters bat0 and the packet *gets encapsulated in the batman-adv packet
>   which adds a batman-adv header and another Ethernet header*
> - the skb enters br1 and gets ruined because nf_bridge_maybe_copy_header() (in
>   br_dev_queue_push_xmit()) will try to restore an header that does not make
>   sense anymore.
> 
> With this patch the nf_bridge gets de-initialised before exiting br0 and
> therefore it is processed properly inside br1: nf_bridge_maybe_copy_header()
> does not take place at all because nf_bridge is never initialised (the packet is
> non-IP since it is a batman-adv packet)
> 
> To the developers of the bridge module I would like to ask:
> 1) is skb->nf_bridge allowed to be non NULL when entering br_dev_xmit() ? If so,
>    when is this supposed to happen?
> 
> 2) do you think this patch is logically correct but the nf_bridge release should
>    be done in batman-adv since it is the one re-encapsulating the packet?
> 
> 
> I hope I have made the problem clear.
> 
> Best regards,
> 
> 
>  net/bridge/br_forward.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/net/bridge/br_forward.c b/net/bridge/br_forward.c
> index 4b81b14..65864bc 100644
> --- a/net/bridge/br_forward.c
> +++ b/net/bridge/br_forward.c
> @@ -49,6 +49,11 @@ int br_dev_queue_push_xmit(struct sk_buff *skb)
>  	} else {
>  		skb_push(skb, ETH_HLEN);
>  		br_drop_fake_rtable(skb);
> +
> +		/* clean the NF bridge data */
> +		nf_bridge_put(skb->nf_bridge);
> +		skb->nf_bridge = NULL;
> +
>  		dev_queue_xmit(skb);
>  	}
>  

You need to bracket this with CONFIG_BRIDGE_NETFILTER
since nf_bridge is only in skbuff if that option is enabled.

Re: [RFC net] bridge: clean the nf_bridge status when forwarding the skb

[Stephen Hemminger]

On Thu, 26 Sep 2013 22:19:50 +0200
Antonio Quartulli <antonio@meshcoding.com> wrote:

> From: Antonio Quartulli <antonio@open-mesh.com>
> 
> Even if enslaving a bridge interface into another bridge is
> forbidden, it is still possible to create a chain of
> virtual interfaces including two distinct bridges.
> 
> In this case, the skb entering the second bridge could have
> the nf_bridge field already set due to a previous operation
> and consequently lead to a wrong processing of the packet
> itself.
> 
> To prevent this behaviour release and set to NULL the
> nf_bridge field of the skb when exiting the bridge interface.
> 
> Signed-off-by: Antonio Quartulli <antonio@open-mesh.com>
> ---
> 
> I am not sure if this is a wanted behaviour or a real BUG. I found this
> "misbehaviour" while testing batman-adv with the following configuration:
> 
> - br0 (bridge interface) having bat0 and eth0 as slaves
> - bat0 (which is a virtual interface provided by the batman-adv module and that
>   works similarly to a bridge - to some extends) having br1 as slave
> - br1 (second bridge interface) having eth1 as slave
> 
> Then follow these events:
> - a broadcast packet arrives on eth0
> - the skb enters br0 and skb->nf_bridge gets initialised and used
> - the skb enters bat0 and the packet *gets encapsulated in the batman-adv packet
>   which adds a batman-adv header and another Ethernet header*
> - the skb enters br1 and gets ruined because nf_bridge_maybe_copy_header() (in
>   br_dev_queue_push_xmit()) will try to restore an header that does not make
>   sense anymore.
> 
> With this patch the nf_bridge gets de-initialised before exiting br0 and
> therefore it is processed properly inside br1: nf_bridge_maybe_copy_header()
> does not take place at all because nf_bridge is never initialised (the packet is
> non-IP since it is a batman-adv packet)
> 
> To the developers of the bridge module I would like to ask:
> 1) is skb->nf_bridge allowed to be non NULL when entering br_dev_xmit() ? If so,
>    when is this supposed to happen?
> 
> 2) do you think this patch is logically correct but the nf_bridge release should
>    be done in batman-adv since it is the one re-encapsulating the packet?
> 
> 
> I hope I have made the problem clear.
> 
> Best regards,
> 
> 
>  net/bridge/br_forward.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/net/bridge/br_forward.c b/net/bridge/br_forward.c
> index 4b81b14..65864bc 100644
> --- a/net/bridge/br_forward.c
> +++ b/net/bridge/br_forward.c
> @@ -49,6 +49,11 @@ int br_dev_queue_push_xmit(struct sk_buff *skb)
>  	} else {
>  		skb_push(skb, ETH_HLEN);
>  		br_drop_fake_rtable(skb);
> +
> +		/* clean the NF bridge data */
> +		nf_bridge_put(skb->nf_bridge);
> +		skb->nf_bridge = NULL;
> +
>  		dev_queue_xmit(skb);
>  	}
>  

You need to bracket this with CONFIG_BRIDGE_NETFILTER
since nf_bridge is only in skbuff if that option is enabled.

Re: [Bridge] [RFC net] bridge: clean the nf_bridge status when forwarding the skb

[Stephen Hemminger]

On Thu, 26 Sep 2013 22:19:50 +0200
Antonio Quartulli <antonio@meshcoding.com> wrote:

> From: Antonio Quartulli <antonio@open-mesh.com>
> 
> Even if enslaving a bridge interface into another bridge is
> forbidden, it is still possible to create a chain of
> virtual interfaces including two distinct bridges.
> 
> In this case, the skb entering the second bridge could have
> the nf_bridge field already set due to a previous operation
> and consequently lead to a wrong processing of the packet
> itself.
> 
> To prevent this behaviour release and set to NULL the
> nf_bridge field of the skb when exiting the bridge interface.
> 
> Signed-off-by: Antonio Quartulli <antonio@open-mesh.com>
> ---
> 
> I am not sure if this is a wanted behaviour or a real BUG. I found this
> "misbehaviour" while testing batman-adv with the following configuration:
> 
> - br0 (bridge interface) having bat0 and eth0 as slaves
> - bat0 (which is a virtual interface provided by the batman-adv module and that
>   works similarly to a bridge - to some extends) having br1 as slave
> - br1 (second bridge interface) having eth1 as slave
> 
> Then follow these events:
> - a broadcast packet arrives on eth0
> - the skb enters br0 and skb->nf_bridge gets initialised and used
> - the skb enters bat0 and the packet *gets encapsulated in the batman-adv packet
>   which adds a batman-adv header and another Ethernet header*
> - the skb enters br1 and gets ruined because nf_bridge_maybe_copy_header() (in
>   br_dev_queue_push_xmit()) will try to restore an header that does not make
>   sense anymore.
> 
> With this patch the nf_bridge gets de-initialised before exiting br0 and
> therefore it is processed properly inside br1: nf_bridge_maybe_copy_header()
> does not take place at all because nf_bridge is never initialised (the packet is
> non-IP since it is a batman-adv packet)
> 
> To the developers of the bridge module I would like to ask:
> 1) is skb->nf_bridge allowed to be non NULL when entering br_dev_xmit() ? If so,
>    when is this supposed to happen?
> 
> 2) do you think this patch is logically correct but the nf_bridge release should
>    be done in batman-adv since it is the one re-encapsulating the packet?
> 
> 
> I hope I have made the problem clear.
> 
> Best regards,
> 
> 
>  net/bridge/br_forward.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/net/bridge/br_forward.c b/net/bridge/br_forward.c
> index 4b81b14..65864bc 100644
> --- a/net/bridge/br_forward.c
> +++ b/net/bridge/br_forward.c
> @@ -49,6 +49,11 @@ int br_dev_queue_push_xmit(struct sk_buff *skb)
>  	} else {
>  		skb_push(skb, ETH_HLEN);
>  		br_drop_fake_rtable(skb);
> +
> +		/* clean the NF bridge data */
> +		nf_bridge_put(skb->nf_bridge);
> +		skb->nf_bridge = NULL;
> +
>  		dev_queue_xmit(skb);
>  	}
>  

I think the header will also be garbage if bridge on bridge with netfilter is used.
See nf_bridge_save_header.

Re: [RFC net] bridge: clean the nf_bridge status when forwarding the skb

[Stephen Hemminger]

On Thu, 26 Sep 2013 22:19:50 +0200
Antonio Quartulli <antonio@meshcoding.com> wrote:

> From: Antonio Quartulli <antonio@open-mesh.com>
> 
> Even if enslaving a bridge interface into another bridge is
> forbidden, it is still possible to create a chain of
> virtual interfaces including two distinct bridges.
> 
> In this case, the skb entering the second bridge could have
> the nf_bridge field already set due to a previous operation
> and consequently lead to a wrong processing of the packet
> itself.
> 
> To prevent this behaviour release and set to NULL the
> nf_bridge field of the skb when exiting the bridge interface.
> 
> Signed-off-by: Antonio Quartulli <antonio@open-mesh.com>
> ---
> 
> I am not sure if this is a wanted behaviour or a real BUG. I found this
> "misbehaviour" while testing batman-adv with the following configuration:
> 
> - br0 (bridge interface) having bat0 and eth0 as slaves
> - bat0 (which is a virtual interface provided by the batman-adv module and that
>   works similarly to a bridge - to some extends) having br1 as slave
> - br1 (second bridge interface) having eth1 as slave
> 
> Then follow these events:
> - a broadcast packet arrives on eth0
> - the skb enters br0 and skb->nf_bridge gets initialised and used
> - the skb enters bat0 and the packet *gets encapsulated in the batman-adv packet
>   which adds a batman-adv header and another Ethernet header*
> - the skb enters br1 and gets ruined because nf_bridge_maybe_copy_header() (in
>   br_dev_queue_push_xmit()) will try to restore an header that does not make
>   sense anymore.
> 
> With this patch the nf_bridge gets de-initialised before exiting br0 and
> therefore it is processed properly inside br1: nf_bridge_maybe_copy_header()
> does not take place at all because nf_bridge is never initialised (the packet is
> non-IP since it is a batman-adv packet)
> 
> To the developers of the bridge module I would like to ask:
> 1) is skb->nf_bridge allowed to be non NULL when entering br_dev_xmit() ? If so,
>    when is this supposed to happen?
> 
> 2) do you think this patch is logically correct but the nf_bridge release should
>    be done in batman-adv since it is the one re-encapsulating the packet?
> 
> 
> I hope I have made the problem clear.
> 
> Best regards,
> 
> 
>  net/bridge/br_forward.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/net/bridge/br_forward.c b/net/bridge/br_forward.c
> index 4b81b14..65864bc 100644
> --- a/net/bridge/br_forward.c
> +++ b/net/bridge/br_forward.c
> @@ -49,6 +49,11 @@ int br_dev_queue_push_xmit(struct sk_buff *skb)
>  	} else {
>  		skb_push(skb, ETH_HLEN);
>  		br_drop_fake_rtable(skb);
> +
> +		/* clean the NF bridge data */
> +		nf_bridge_put(skb->nf_bridge);
> +		skb->nf_bridge = NULL;
> +
>  		dev_queue_xmit(skb);
>  	}
>  

I think the header will also be garbage if bridge on bridge with netfilter is used.
See nf_bridge_save_header.

Re: [Bridge] [RFC net] bridge: clean the nf_bridge status when forwarding the skb

[Antonio Quartulli]

[-- Attachment #1: Type: text/plain, Size: 3479 bytes --]

On Thu, Sep 26, 2013 at 02:10:21PM -0700, Stephen Hemminger wrote:
> On Thu, 26 Sep 2013 22:19:50 +0200
> Antonio Quartulli <antonio@meshcoding.com> wrote:
> 
> > From: Antonio Quartulli <antonio@open-mesh.com>
> > 
> > Even if enslaving a bridge interface into another bridge is
> > forbidden, it is still possible to create a chain of
> > virtual interfaces including two distinct bridges.
> > 
> > In this case, the skb entering the second bridge could have
> > the nf_bridge field already set due to a previous operation
> > and consequently lead to a wrong processing of the packet
> > itself.
> > 
> > To prevent this behaviour release and set to NULL the
> > nf_bridge field of the skb when exiting the bridge interface.
> > 
> > Signed-off-by: Antonio Quartulli <antonio@open-mesh.com>
> > ---
> > 
> > I am not sure if this is a wanted behaviour or a real BUG. I found this
> > "misbehaviour" while testing batman-adv with the following configuration:
> > 
> > - br0 (bridge interface) having bat0 and eth0 as slaves
> > - bat0 (which is a virtual interface provided by the batman-adv module and that
> >   works similarly to a bridge - to some extends) having br1 as slave
> > - br1 (second bridge interface) having eth1 as slave
> > 
> > Then follow these events:
> > - a broadcast packet arrives on eth0
> > - the skb enters br0 and skb->nf_bridge gets initialised and used
> > - the skb enters bat0 and the packet *gets encapsulated in the batman-adv packet
> >   which adds a batman-adv header and another Ethernet header*
> > - the skb enters br1 and gets ruined because nf_bridge_maybe_copy_header() (in
> >   br_dev_queue_push_xmit()) will try to restore an header that does not make
> >   sense anymore.
> > 
> > With this patch the nf_bridge gets de-initialised before exiting br0 and
> > therefore it is processed properly inside br1: nf_bridge_maybe_copy_header()
> > does not take place at all because nf_bridge is never initialised (the packet is
> > non-IP since it is a batman-adv packet)
> > 
> > To the developers of the bridge module I would like to ask:
> > 1) is skb->nf_bridge allowed to be non NULL when entering br_dev_xmit() ? If so,
> >    when is this supposed to happen?
> > 
> > 2) do you think this patch is logically correct but the nf_bridge release should
> >    be done in batman-adv since it is the one re-encapsulating the packet?
> > 
> > 
> > I hope I have made the problem clear.
> > 
> > Best regards,
> > 
> > 
> >  net/bridge/br_forward.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> > 
> > diff --git a/net/bridge/br_forward.c b/net/bridge/br_forward.c
> > index 4b81b14..65864bc 100644
> > --- a/net/bridge/br_forward.c
> > +++ b/net/bridge/br_forward.c
> > @@ -49,6 +49,11 @@ int br_dev_queue_push_xmit(struct sk_buff *skb)
> >  	} else {
> >  		skb_push(skb, ETH_HLEN);
> >  		br_drop_fake_rtable(skb);
> > +
> > +		/* clean the NF bridge data */
> > +		nf_bridge_put(skb->nf_bridge);
> > +		skb->nf_bridge = NULL;
> > +
> >  		dev_queue_xmit(skb);
> >  	}
> >  

Regarding CONFIG_BRIDGE_NETFILTER you are right, thanks.

> 
> I think the header will also be garbage if bridge on bridge with netfilter is used.
> See nf_bridge_save_header.

What header are you referring to? nf_bridge_save_header() saves the header in
skb->nf_bridge->data, which is freed during nf_bridge_put() (assuming
->use reached 0).


-- 
Antonio Quartulli

[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 836 bytes --]

Re: [RFC net] bridge: clean the nf_bridge status when forwarding the skb

[Antonio Quartulli]

[-- Attachment #1: Type: text/plain, Size: 3479 bytes --]

On Thu, Sep 26, 2013 at 02:10:21PM -0700, Stephen Hemminger wrote:
> On Thu, 26 Sep 2013 22:19:50 +0200
> Antonio Quartulli <antonio@meshcoding.com> wrote:
> 
> > From: Antonio Quartulli <antonio@open-mesh.com>
> > 
> > Even if enslaving a bridge interface into another bridge is
> > forbidden, it is still possible to create a chain of
> > virtual interfaces including two distinct bridges.
> > 
> > In this case, the skb entering the second bridge could have
> > the nf_bridge field already set due to a previous operation
> > and consequently lead to a wrong processing of the packet
> > itself.
> > 
> > To prevent this behaviour release and set to NULL the
> > nf_bridge field of the skb when exiting the bridge interface.
> > 
> > Signed-off-by: Antonio Quartulli <antonio@open-mesh.com>
> > ---
> > 
> > I am not sure if this is a wanted behaviour or a real BUG. I found this
> > "misbehaviour" while testing batman-adv with the following configuration:
> > 
> > - br0 (bridge interface) having bat0 and eth0 as slaves
> > - bat0 (which is a virtual interface provided by the batman-adv module and that
> >   works similarly to a bridge - to some extends) having br1 as slave
> > - br1 (second bridge interface) having eth1 as slave
> > 
> > Then follow these events:
> > - a broadcast packet arrives on eth0
> > - the skb enters br0 and skb->nf_bridge gets initialised and used
> > - the skb enters bat0 and the packet *gets encapsulated in the batman-adv packet
> >   which adds a batman-adv header and another Ethernet header*
> > - the skb enters br1 and gets ruined because nf_bridge_maybe_copy_header() (in
> >   br_dev_queue_push_xmit()) will try to restore an header that does not make
> >   sense anymore.
> > 
> > With this patch the nf_bridge gets de-initialised before exiting br0 and
> > therefore it is processed properly inside br1: nf_bridge_maybe_copy_header()
> > does not take place at all because nf_bridge is never initialised (the packet is
> > non-IP since it is a batman-adv packet)
> > 
> > To the developers of the bridge module I would like to ask:
> > 1) is skb->nf_bridge allowed to be non NULL when entering br_dev_xmit() ? If so,
> >    when is this supposed to happen?
> > 
> > 2) do you think this patch is logically correct but the nf_bridge release should
> >    be done in batman-adv since it is the one re-encapsulating the packet?
> > 
> > 
> > I hope I have made the problem clear.
> > 
> > Best regards,
> > 
> > 
> >  net/bridge/br_forward.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> > 
> > diff --git a/net/bridge/br_forward.c b/net/bridge/br_forward.c
> > index 4b81b14..65864bc 100644
> > --- a/net/bridge/br_forward.c
> > +++ b/net/bridge/br_forward.c
> > @@ -49,6 +49,11 @@ int br_dev_queue_push_xmit(struct sk_buff *skb)
> >  	} else {
> >  		skb_push(skb, ETH_HLEN);
> >  		br_drop_fake_rtable(skb);
> > +
> > +		/* clean the NF bridge data */
> > +		nf_bridge_put(skb->nf_bridge);
> > +		skb->nf_bridge = NULL;
> > +
> >  		dev_queue_xmit(skb);
> >  	}
> >  

Regarding CONFIG_BRIDGE_NETFILTER you are right, thanks.

> 
> I think the header will also be garbage if bridge on bridge with netfilter is used.
> See nf_bridge_save_header.

What header are you referring to? nf_bridge_save_header() saves the header in
skb->nf_bridge->data, which is freed during nf_bridge_put() (assuming
->use reached 0).


-- 
Antonio Quartulli

[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 836 bytes --]

Re: [Bridge] [RFC net] bridge: clean the nf_bridge status when forwarding the skb

[Stephen Hemminger]

On Thu, 26 Sep 2013 23:16:48 +0200
Antonio Quartulli <antonio@open-mesh.com> wrote:

> On Thu, Sep 26, 2013 at 02:10:21PM -0700, Stephen Hemminger wrote:
> > On Thu, 26 Sep 2013 22:19:50 +0200
> > Antonio Quartulli <antonio@meshcoding.com> wrote:
> > 
> > > From: Antonio Quartulli <antonio@open-mesh.com>
> > > 
> > > Even if enslaving a bridge interface into another bridge is
> > > forbidden, it is still possible to create a chain of
> > > virtual interfaces including two distinct bridges.
> > > 
> > > In this case, the skb entering the second bridge could have
> > > the nf_bridge field already set due to a previous operation
> > > and consequently lead to a wrong processing of the packet
> > > itself.
> > > 
> > > To prevent this behaviour release and set to NULL the
> > > nf_bridge field of the skb when exiting the bridge interface.
> > > 
> > > Signed-off-by: Antonio Quartulli <antonio@open-mesh.com>
> > > ---
> > > 
> > > I am not sure if this is a wanted behaviour or a real BUG. I found this
> > > "misbehaviour" while testing batman-adv with the following configuration:
> > > 
> > > - br0 (bridge interface) having bat0 and eth0 as slaves
> > > - bat0 (which is a virtual interface provided by the batman-adv module and that
> > >   works similarly to a bridge - to some extends) having br1 as slave
> > > - br1 (second bridge interface) having eth1 as slave
> > > 
> > > Then follow these events:
> > > - a broadcast packet arrives on eth0
> > > - the skb enters br0 and skb->nf_bridge gets initialised and used
> > > - the skb enters bat0 and the packet *gets encapsulated in the batman-adv packet
> > >   which adds a batman-adv header and another Ethernet header*
> > > - the skb enters br1 and gets ruined because nf_bridge_maybe_copy_header() (in
> > >   br_dev_queue_push_xmit()) will try to restore an header that does not make
> > >   sense anymore.
> > > 
> > > With this patch the nf_bridge gets de-initialised before exiting br0 and
> > > therefore it is processed properly inside br1: nf_bridge_maybe_copy_header()
> > > does not take place at all because nf_bridge is never initialised (the packet is
> > > non-IP since it is a batman-adv packet)
> > > 
> > > To the developers of the bridge module I would like to ask:
> > > 1) is skb->nf_bridge allowed to be non NULL when entering br_dev_xmit() ? If so,
> > >    when is this supposed to happen?
> > > 
> > > 2) do you think this patch is logically correct but the nf_bridge release should
> > >    be done in batman-adv since it is the one re-encapsulating the packet?
> > > 
> > > 
> > > I hope I have made the problem clear.
> > > 
> > > Best regards,
> > > 
> > > 
> > >  net/bridge/br_forward.c | 5 +++++
> > >  1 file changed, 5 insertions(+)
> > > 
> > > diff --git a/net/bridge/br_forward.c b/net/bridge/br_forward.c
> > > index 4b81b14..65864bc 100644
> > > --- a/net/bridge/br_forward.c
> > > +++ b/net/bridge/br_forward.c
> > > @@ -49,6 +49,11 @@ int br_dev_queue_push_xmit(struct sk_buff *skb)
> > >  	} else {
> > >  		skb_push(skb, ETH_HLEN);
> > >  		br_drop_fake_rtable(skb);
> > > +
> > > +		/* clean the NF bridge data */
> > > +		nf_bridge_put(skb->nf_bridge);
> > > +		skb->nf_bridge = NULL;
> > > +
> > >  		dev_queue_xmit(skb);
> > >  	}
> > >  
> 
> Regarding CONFIG_BRIDGE_NETFILTER you are right, thanks.
> 
> > 
> > I think the header will also be garbage if bridge on bridge with netfilter is used.
> > See nf_bridge_save_header.
> 
> What header are you referring to? nf_bridge_save_header() saves the header in
> skb->nf_bridge->data, which is freed during nf_bridge_put() (assuming
> ->use reached 0).
> 
> 

If bridge is stacked the original ether header will get overwritten by the second
call to save_header.

Re: [RFC net] bridge: clean the nf_bridge status when forwarding the skb

[Stephen Hemminger]

On Thu, 26 Sep 2013 23:16:48 +0200
Antonio Quartulli <antonio@open-mesh.com> wrote:

> On Thu, Sep 26, 2013 at 02:10:21PM -0700, Stephen Hemminger wrote:
> > On Thu, 26 Sep 2013 22:19:50 +0200
> > Antonio Quartulli <antonio@meshcoding.com> wrote:
> > 
> > > From: Antonio Quartulli <antonio@open-mesh.com>
> > > 
> > > Even if enslaving a bridge interface into another bridge is
> > > forbidden, it is still possible to create a chain of
> > > virtual interfaces including two distinct bridges.
> > > 
> > > In this case, the skb entering the second bridge could have
> > > the nf_bridge field already set due to a previous operation
> > > and consequently lead to a wrong processing of the packet
> > > itself.
> > > 
> > > To prevent this behaviour release and set to NULL the
> > > nf_bridge field of the skb when exiting the bridge interface.
> > > 
> > > Signed-off-by: Antonio Quartulli <antonio@open-mesh.com>
> > > ---
> > > 
> > > I am not sure if this is a wanted behaviour or a real BUG. I found this
> > > "misbehaviour" while testing batman-adv with the following configuration:
> > > 
> > > - br0 (bridge interface) having bat0 and eth0 as slaves
> > > - bat0 (which is a virtual interface provided by the batman-adv module and that
> > >   works similarly to a bridge - to some extends) having br1 as slave
> > > - br1 (second bridge interface) having eth1 as slave
> > > 
> > > Then follow these events:
> > > - a broadcast packet arrives on eth0
> > > - the skb enters br0 and skb->nf_bridge gets initialised and used
> > > - the skb enters bat0 and the packet *gets encapsulated in the batman-adv packet
> > >   which adds a batman-adv header and another Ethernet header*
> > > - the skb enters br1 and gets ruined because nf_bridge_maybe_copy_header() (in
> > >   br_dev_queue_push_xmit()) will try to restore an header that does not make
> > >   sense anymore.
> > > 
> > > With this patch the nf_bridge gets de-initialised before exiting br0 and
> > > therefore it is processed properly inside br1: nf_bridge_maybe_copy_header()
> > > does not take place at all because nf_bridge is never initialised (the packet is
> > > non-IP since it is a batman-adv packet)
> > > 
> > > To the developers of the bridge module I would like to ask:
> > > 1) is skb->nf_bridge allowed to be non NULL when entering br_dev_xmit() ? If so,
> > >    when is this supposed to happen?
> > > 
> > > 2) do you think this patch is logically correct but the nf_bridge release should
> > >    be done in batman-adv since it is the one re-encapsulating the packet?
> > > 
> > > 
> > > I hope I have made the problem clear.
> > > 
> > > Best regards,
> > > 
> > > 
> > >  net/bridge/br_forward.c | 5 +++++
> > >  1 file changed, 5 insertions(+)
> > > 
> > > diff --git a/net/bridge/br_forward.c b/net/bridge/br_forward.c
> > > index 4b81b14..65864bc 100644
> > > --- a/net/bridge/br_forward.c
> > > +++ b/net/bridge/br_forward.c
> > > @@ -49,6 +49,11 @@ int br_dev_queue_push_xmit(struct sk_buff *skb)
> > >  	} else {
> > >  		skb_push(skb, ETH_HLEN);
> > >  		br_drop_fake_rtable(skb);
> > > +
> > > +		/* clean the NF bridge data */
> > > +		nf_bridge_put(skb->nf_bridge);
> > > +		skb->nf_bridge = NULL;
> > > +
> > >  		dev_queue_xmit(skb);
> > >  	}
> > >  
> 
> Regarding CONFIG_BRIDGE_NETFILTER you are right, thanks.
> 
> > 
> > I think the header will also be garbage if bridge on bridge with netfilter is used.
> > See nf_bridge_save_header.
> 
> What header are you referring to? nf_bridge_save_header() saves the header in
> skb->nf_bridge->data, which is freed during nf_bridge_put() (assuming
> ->use reached 0).
> 
> 

If bridge is stacked the original ether header will get overwritten by the second
call to save_header.

Re: [Bridge] [RFC net] bridge: clean the nf_bridge status when forwarding the skb

[Antonio Quartulli]

[-- Attachment #1: Type: text/plain, Size: 1943 bytes --]

On Thu, Sep 26, 2013 at 02:32:48PM -0700, Stephen Hemminger wrote:
> > > > diff --git a/net/bridge/br_forward.c b/net/bridge/br_forward.c
> > > > index 4b81b14..65864bc 100644
> > > > --- a/net/bridge/br_forward.c
> > > > +++ b/net/bridge/br_forward.c
> > > > @@ -49,6 +49,11 @@ int br_dev_queue_push_xmit(struct sk_buff *skb)
> > > >  	} else {
> > > >  		skb_push(skb, ETH_HLEN);
> > > >  		br_drop_fake_rtable(skb);
> > > > +
> > > > +		/* clean the NF bridge data */
> > > > +		nf_bridge_put(skb->nf_bridge);
> > > > +		skb->nf_bridge = NULL;
> > > > +
> > > >  		dev_queue_xmit(skb);
> > > >  	}
> > > >  
> > 
> > Regarding CONFIG_BRIDGE_NETFILTER you are right, thanks.
> > 
> > > 
> > > I think the header will also be garbage if bridge on bridge with netfilter is used.
> > > See nf_bridge_save_header.
> > 
> > What header are you referring to? nf_bridge_save_header() saves the header in
> > skb->nf_bridge->data, which is freed during nf_bridge_put() (assuming
> > ->use reached 0).
> > 
> > 
> 
> If bridge is stacked the original ether header will get overwritten by the second
> call to save_header.

Sorry, but I am not getting what you mean (I am new to the code and it is late here..):
save_header() will store the Ethernet header in nf_bridge->data for
later recover (if needed).

By freeing nf_bridge I also destroy this header copy.

When the skb enters the second bridge, save_header() will save again the header
in nf_bridge->data. But I don't see how this can create a problem.

The problem I had before this patch comes from the fact that
nf_bridge_copy_header() is invoked in the second bridge with the nf_bridge state
of the first. This was overwriting my the packet Ethernet header with what the
first invocation of save_header() stored in nf_bridge->data.

But by unsetting nf_bridge I think I am preventing this from happening again.
no?

-- 
Antonio Quartulli

[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 836 bytes --]

Re: [RFC net] bridge: clean the nf_bridge status when forwarding the skb

[Antonio Quartulli]

[-- Attachment #1: Type: text/plain, Size: 1943 bytes --]

On Thu, Sep 26, 2013 at 02:32:48PM -0700, Stephen Hemminger wrote:
> > > > diff --git a/net/bridge/br_forward.c b/net/bridge/br_forward.c
> > > > index 4b81b14..65864bc 100644
> > > > --- a/net/bridge/br_forward.c
> > > > +++ b/net/bridge/br_forward.c
> > > > @@ -49,6 +49,11 @@ int br_dev_queue_push_xmit(struct sk_buff *skb)
> > > >  	} else {
> > > >  		skb_push(skb, ETH_HLEN);
> > > >  		br_drop_fake_rtable(skb);
> > > > +
> > > > +		/* clean the NF bridge data */
> > > > +		nf_bridge_put(skb->nf_bridge);
> > > > +		skb->nf_bridge = NULL;
> > > > +
> > > >  		dev_queue_xmit(skb);
> > > >  	}
> > > >  
> > 
> > Regarding CONFIG_BRIDGE_NETFILTER you are right, thanks.
> > 
> > > 
> > > I think the header will also be garbage if bridge on bridge with netfilter is used.
> > > See nf_bridge_save_header.
> > 
> > What header are you referring to? nf_bridge_save_header() saves the header in
> > skb->nf_bridge->data, which is freed during nf_bridge_put() (assuming
> > ->use reached 0).
> > 
> > 
> 
> If bridge is stacked the original ether header will get overwritten by the second
> call to save_header.

Sorry, but I am not getting what you mean (I am new to the code and it is late here..):
save_header() will store the Ethernet header in nf_bridge->data for
later recover (if needed).

By freeing nf_bridge I also destroy this header copy.

When the skb enters the second bridge, save_header() will save again the header
in nf_bridge->data. But I don't see how this can create a problem.

The problem I had before this patch comes from the fact that
nf_bridge_copy_header() is invoked in the second bridge with the nf_bridge state
of the first. This was overwriting my the packet Ethernet header with what the
first invocation of save_header() stored in nf_bridge->data.

But by unsetting nf_bridge I think I am preventing this from happening again.
no?

-- 
Antonio Quartulli

[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 836 bytes --]

Re: [Bridge] [RFC net] bridge: clean the nf_bridge status when forwarding the skb

[Antonio Quartulli]

[-- Attachment #1: Type: text/plain, Size: 2351 bytes --]

On Fri, Sep 27, 2013 at 12:01:43AM +0200, Antonio Quartulli wrote:
> On Thu, Sep 26, 2013 at 02:32:48PM -0700, Stephen Hemminger wrote:
> > > > > diff --git a/net/bridge/br_forward.c b/net/bridge/br_forward.c
> > > > > index 4b81b14..65864bc 100644
> > > > > --- a/net/bridge/br_forward.c
> > > > > +++ b/net/bridge/br_forward.c
> > > > > @@ -49,6 +49,11 @@ int br_dev_queue_push_xmit(struct sk_buff *skb)
> > > > >  	} else {
> > > > >  		skb_push(skb, ETH_HLEN);
> > > > >  		br_drop_fake_rtable(skb);
> > > > > +
> > > > > +		/* clean the NF bridge data */
> > > > > +		nf_bridge_put(skb->nf_bridge);
> > > > > +		skb->nf_bridge = NULL;
> > > > > +
> > > > >  		dev_queue_xmit(skb);
> > > > >  	}
> > > > >  
> > > 
> > > Regarding CONFIG_BRIDGE_NETFILTER you are right, thanks.
> > > 
> > > > 
> > > > I think the header will also be garbage if bridge on bridge with netfilter is used.
> > > > See nf_bridge_save_header.
> > > 
> > > What header are you referring to? nf_bridge_save_header() saves the header in
> > > skb->nf_bridge->data, which is freed during nf_bridge_put() (assuming
> > > ->use reached 0).
> > > 
> > > 
> > 
> > If bridge is stacked the original ether header will get overwritten by the second
> > call to save_header.
> 
> Sorry, but I am not getting what you mean (I am new to the code and it is late here..):
> save_header() will store the Ethernet header in nf_bridge->data for
> later recover (if needed).
> 
> By freeing nf_bridge I also destroy this header copy.
> 
> When the skb enters the second bridge, save_header() will save again the header
> in nf_bridge->data. But I don't see how this can create a problem.
> 
> The problem I had before this patch comes from the fact that
> nf_bridge_copy_header() is invoked in the second bridge with the nf_bridge state
> of the first. This was overwriting my the packet Ethernet header with what the
> first invocation of save_header() stored in nf_bridge->data.
> 
> But by unsetting nf_bridge I think I am preventing this from happening again.
> no?

Hello Stephen,

do you have other comments about this patch? I know it is rather difficult that
a generic user hits this issue, but I'd like to see it fixed because other
people using batman-adv may incur in this problem.

Cheers,


-- 
Antonio Quartulli

[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 836 bytes --]

Re: [RFC net] bridge: clean the nf_bridge status when forwarding the skb

[Antonio Quartulli]

[-- Attachment #1: Type: text/plain, Size: 2351 bytes --]

On Fri, Sep 27, 2013 at 12:01:43AM +0200, Antonio Quartulli wrote:
> On Thu, Sep 26, 2013 at 02:32:48PM -0700, Stephen Hemminger wrote:
> > > > > diff --git a/net/bridge/br_forward.c b/net/bridge/br_forward.c
> > > > > index 4b81b14..65864bc 100644
> > > > > --- a/net/bridge/br_forward.c
> > > > > +++ b/net/bridge/br_forward.c
> > > > > @@ -49,6 +49,11 @@ int br_dev_queue_push_xmit(struct sk_buff *skb)
> > > > >  	} else {
> > > > >  		skb_push(skb, ETH_HLEN);
> > > > >  		br_drop_fake_rtable(skb);
> > > > > +
> > > > > +		/* clean the NF bridge data */
> > > > > +		nf_bridge_put(skb->nf_bridge);
> > > > > +		skb->nf_bridge = NULL;
> > > > > +
> > > > >  		dev_queue_xmit(skb);
> > > > >  	}
> > > > >  
> > > 
> > > Regarding CONFIG_BRIDGE_NETFILTER you are right, thanks.
> > > 
> > > > 
> > > > I think the header will also be garbage if bridge on bridge with netfilter is used.
> > > > See nf_bridge_save_header.
> > > 
> > > What header are you referring to? nf_bridge_save_header() saves the header in
> > > skb->nf_bridge->data, which is freed during nf_bridge_put() (assuming
> > > ->use reached 0).
> > > 
> > > 
> > 
> > If bridge is stacked the original ether header will get overwritten by the second
> > call to save_header.
> 
> Sorry, but I am not getting what you mean (I am new to the code and it is late here..):
> save_header() will store the Ethernet header in nf_bridge->data for
> later recover (if needed).
> 
> By freeing nf_bridge I also destroy this header copy.
> 
> When the skb enters the second bridge, save_header() will save again the header
> in nf_bridge->data. But I don't see how this can create a problem.
> 
> The problem I had before this patch comes from the fact that
> nf_bridge_copy_header() is invoked in the second bridge with the nf_bridge state
> of the first. This was overwriting my the packet Ethernet header with what the
> first invocation of save_header() stored in nf_bridge->data.
> 
> But by unsetting nf_bridge I think I am preventing this from happening again.
> no?

Hello Stephen,

do you have other comments about this patch? I know it is rather difficult that
a generic user hits this issue, but I'd like to see it fixed because other
people using batman-adv may incur in this problem.

Cheers,


-- 
Antonio Quartulli

[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 836 bytes --]

Re: [Bridge] [RFC net] bridge: clean the nf_bridge status when forwarding the skb

[Stephen Hemminger]

On Tue, 15 Oct 2013 00:20:10 +0200
Antonio Quartulli <antonio@meshcoding.com> wrote:

> On Fri, Sep 27, 2013 at 12:01:43AM +0200, Antonio Quartulli wrote:
> > On Thu, Sep 26, 2013 at 02:32:48PM -0700, Stephen Hemminger wrote:
> > > > > > diff --git a/net/bridge/br_forward.c b/net/bridge/br_forward.c
> > > > > > index 4b81b14..65864bc 100644
> > > > > > --- a/net/bridge/br_forward.c
> > > > > > +++ b/net/bridge/br_forward.c
> > > > > > @@ -49,6 +49,11 @@ int br_dev_queue_push_xmit(struct sk_buff *skb)
> > > > > >  	} else {
> > > > > >  		skb_push(skb, ETH_HLEN);
> > > > > >  		br_drop_fake_rtable(skb);
> > > > > > +
> > > > > > +		/* clean the NF bridge data */
> > > > > > +		nf_bridge_put(skb->nf_bridge);
> > > > > > +		skb->nf_bridge = NULL;
> > > > > > +
> > > > > >  		dev_queue_xmit(skb);
> > > > > >  	}
> > > > > >  
> > > > 
> > > > Regarding CONFIG_BRIDGE_NETFILTER you are right, thanks.
> > > > 
> > > > > 
> > > > > I think the header will also be garbage if bridge on bridge with netfilter is used.
> > > > > See nf_bridge_save_header.
> > > > 
> > > > What header are you referring to? nf_bridge_save_header() saves the header in
> > > > skb->nf_bridge->data, which is freed during nf_bridge_put() (assuming
> > > > ->use reached 0).
> > > > 
> > > > 
> > > 
> > > If bridge is stacked the original ether header will get overwritten by the second
> > > call to save_header.
> > 
> > Sorry, but I am not getting what you mean (I am new to the code and it is late here..):
> > save_header() will store the Ethernet header in nf_bridge->data for
> > later recover (if needed).
> > 
> > By freeing nf_bridge I also destroy this header copy.
> > 
> > When the skb enters the second bridge, save_header() will save again the header
> > in nf_bridge->data. But I don't see how this can create a problem.
> > 
> > The problem I had before this patch comes from the fact that
> > nf_bridge_copy_header() is invoked in the second bridge with the nf_bridge state
> > of the first. This was overwriting my the packet Ethernet header with what the
> > first invocation of save_header() stored in nf_bridge->data.
> > 
> > But by unsetting nf_bridge I think I am preventing this from happening again.
> > no?
> 
> Hello Stephen,
> 
> do you have other comments about this patch? I know it is rather difficult that
> a generic user hits this issue, but I'd like to see it fixed because other
> people using batman-adv may incur in this problem.
> 
> Cheers,
> 
> 

The patch content is fine, but it needs necessary ifdef's.
I would also prefer to have the clean done as a function that can be stubbed out
like the other bridge netfilter stuff. 

Re: [RFC net] bridge: clean the nf_bridge status when forwarding the skb

[Stephen Hemminger]

On Tue, 15 Oct 2013 00:20:10 +0200
Antonio Quartulli <antonio@meshcoding.com> wrote:

> On Fri, Sep 27, 2013 at 12:01:43AM +0200, Antonio Quartulli wrote:
> > On Thu, Sep 26, 2013 at 02:32:48PM -0700, Stephen Hemminger wrote:
> > > > > > diff --git a/net/bridge/br_forward.c b/net/bridge/br_forward.c
> > > > > > index 4b81b14..65864bc 100644
> > > > > > --- a/net/bridge/br_forward.c
> > > > > > +++ b/net/bridge/br_forward.c
> > > > > > @@ -49,6 +49,11 @@ int br_dev_queue_push_xmit(struct sk_buff *skb)
> > > > > >  	} else {
> > > > > >  		skb_push(skb, ETH_HLEN);
> > > > > >  		br_drop_fake_rtable(skb);
> > > > > > +
> > > > > > +		/* clean the NF bridge data */
> > > > > > +		nf_bridge_put(skb->nf_bridge);
> > > > > > +		skb->nf_bridge = NULL;
> > > > > > +
> > > > > >  		dev_queue_xmit(skb);
> > > > > >  	}
> > > > > >  
> > > > 
> > > > Regarding CONFIG_BRIDGE_NETFILTER you are right, thanks.
> > > > 
> > > > > 
> > > > > I think the header will also be garbage if bridge on bridge with netfilter is used.
> > > > > See nf_bridge_save_header.
> > > > 
> > > > What header are you referring to? nf_bridge_save_header() saves the header in
> > > > skb->nf_bridge->data, which is freed during nf_bridge_put() (assuming
> > > > ->use reached 0).
> > > > 
> > > > 
> > > 
> > > If bridge is stacked the original ether header will get overwritten by the second
> > > call to save_header.
> > 
> > Sorry, but I am not getting what you mean (I am new to the code and it is late here..):
> > save_header() will store the Ethernet header in nf_bridge->data for
> > later recover (if needed).
> > 
> > By freeing nf_bridge I also destroy this header copy.
> > 
> > When the skb enters the second bridge, save_header() will save again the header
> > in nf_bridge->data. But I don't see how this can create a problem.
> > 
> > The problem I had before this patch comes from the fact that
> > nf_bridge_copy_header() is invoked in the second bridge with the nf_bridge state
> > of the first. This was overwriting my the packet Ethernet header with what the
> > first invocation of save_header() stored in nf_bridge->data.
> > 
> > But by unsetting nf_bridge I think I am preventing this from happening again.
> > no?
> 
> Hello Stephen,
> 
> do you have other comments about this patch? I know it is rather difficult that
> a generic user hits this issue, but I'd like to see it fixed because other
> people using batman-adv may incur in this problem.
> 
> Cheers,
> 
> 

The patch content is fine, but it needs necessary ifdef's.
I would also prefer to have the clean done as a function that can be stubbed out
like the other bridge netfilter stuff. 

Re: [Bridge] [RFC net] bridge: clean the nf_bridge status when forwarding the skb

[Antonio Quartulli]

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On Mon, Oct 14, 2013 at 03:27:56PM -0700, Stephen Hemminger wrote:
> The patch content is fine, but it needs necessary ifdef's.
> I would also prefer to have the clean done as a function that can be stubbed out
> like the other bridge netfilter stuff. 
> 


Ok, I will apply those changes and I will send it as PATCH.

Thank you very much for your feedback!


Regards,


-- 
Antonio Quartulli

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Re: [RFC net] bridge: clean the nf_bridge status when forwarding the skb

[Antonio Quartulli]

[-- Attachment #1: Type: text/plain, Size: 410 bytes --]

On Mon, Oct 14, 2013 at 03:27:56PM -0700, Stephen Hemminger wrote:
> The patch content is fine, but it needs necessary ifdef's.
> I would also prefer to have the clean done as a function that can be stubbed out
> like the other bridge netfilter stuff. 
> 


Ok, I will apply those changes and I will send it as PATCH.

Thank you very much for your feedback!


Regards,


-- 
Antonio Quartulli

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