Updated diffs addressing Stephens comments

diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
index d9d1e2b..a401ed4 100644
--- a/net/bridge/br_if.c
+++ b/net/bridge/br_if.c

@@ -214,6 +214,7 @@ static struct net_device *new_bridge_dev(struct

net *net, const char *name)
 	br->topology_change = 0;
 	br->topology_change_detected = 0;
 	br->ageing_time = 300 * HZ;
+	br->pae_forward = false;

 	br_netfilter_rtable_init(br);

diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
index 90e985b..79b03fa 100644
--- a/net/bridge/br_input.c
+++ b/net/bridge/br_input.c

@@ -98,6 +98,14 @@ int br_handle_frame_finish(struct sk_buff *skb)
 	}

 	if (skb) {
+		/* Prevent Crosstalk where a Supplicant on one Port attempts to
+		 * interfere with authentications occurring on another Port.
+		 * (IEEE Std 802.1X-2001 C.3.3)
+		 */
+		if (unlikely(!br->pae_forward &&
+		    skb->protocol == htons(ETH_P_PAE)))
+			goto drop;
+
 		if (dst)
 			br_forward(dst->dst, skb, skb2);
 		else

@@ -166,6 +174,10 @@ struct sk_buff *br_handle_frame(struct sk_buff *skb)
 		if (p->br->stp_enabled == BR_NO_STP && dest[5] == 0)
 			goto forward;

+		/* Check if PAE frame should be forwarded */
+		if (p->br->pae_forward && skb->protocol == htons(ETH_P_PAE))
+			goto forward;
+
 		if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev,
 			    NULL, br_handle_local_finish))
 			return NULL;	/* frame consumed by filter */

diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index 4e1b620..8977d66 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h

@@ -244,6 +244,8 @@ struct net_bridge
 	struct timer_list		multicast_query_timer;
 #endif

+	bool pae_forward;		/* 802.1x frames forwarded / dropped */
+
 	struct timer_list		hello_timer;
 	struct timer_list		tcn_timer;
 	struct timer_list		topology_change_timer;

diff --git a/net/bridge/br_sysfs_br.c b/net/bridge/br_sysfs_br.c
index 5c1e555..de3550f 100644
--- a/net/bridge/br_sysfs_br.c
+++ b/net/bridge/br_sysfs_br.c

@@ -679,6 +679,28 @@ static DEVICE_ATTR(nf_call_arptables, S_IRUGO | S_IWUSR,
 		   show_nf_call_arptables, store_nf_call_arptables);
 #endif

+static ssize_t show_pae_forward(struct device *d, struct

device_attribute *attr,
+				char *buf)
+{
+	struct net_bridge *br = to_bridge(d);
+	return sprintf(buf, "%d\n", br->pae_forward);
+}
+
+static int set_pae_forward(struct net_bridge *br, unsigned long val)
+{
+	br->pae_forward = val ? true : false;
+	return 0;
+}
+
+static ssize_t store_pae_forward(struct device *d,
+				 struct device_attribute *attr, const char *buf,
+				 size_t len)
+{
+	return store_bridge_parm(d, buf, len, set_pae_forward);
+}
+static DEVICE_ATTR(pae_forward, S_IRUGO | S_IWUSR, show_pae_forward,
+		   store_pae_forward);
+
 static struct attribute *bridge_attrs[] = {
 	&dev_attr_forward_delay.attr,
 	&dev_attr_hello_time.attr,

@@ -698,6 +720,7 @@ static struct attribute *bridge_attrs[] = {
 	&dev_attr_gc_timer.attr,
 	&dev_attr_group_addr.attr,
 	&dev_attr_flush.attr,
+	&dev_attr_pae_forward.attr,
 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
 	&dev_attr_multicast_router.attr,
 	&dev_attr_multicast_snooping.attr,

On 24 June 2011 22:29, Nick Carter [off-list ref] wrote:

On 24 June 2011 20:08, Stephen Hemminger
[off-list ref] wrote:

quoted

On Fri, 24 Jun 2011 19:29:41 +0100
Nick Carter [off-list ref] wrote:

quoted

New diffs below with the Kconfig option removed as requested.

Now all users and distro's will get the correct 802.1x bridge
behaviour by default.  That is EAPOL frames attempting to traverse the
bridge will be dropped (IEEE Std 802.1X-2001 C.3.3).

Users or distro's who want the non-standard behaviour of forwarding
EAPOL frames, can use a simple runtime configuration change to the
sysfs bridge/pae_forward attribute.

This is much better, thanks.
See the comments for how to make the code more compact and tighter.

quoted

diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
index d9d1e2b..91c1b71 100644
--- a/net/bridge/br_if.c
+++ b/net/bridge/br_if.c

@@ -214,6 +214,7 @@ static struct net_device *new_bridge_dev(struct

net *net, const char *name)
      br->topology_change = 0;
      br->topology_change_detected = 0;
      br->ageing_time = 300 * HZ;
+     br->pae_forward = BR_PAE_DEFAULT;

It is just a boolean, why the verbose enum values?

In case we want BR_PAE_<foo> in the future, not that I can think of a
3rd option now.  So happy to change to a boolean.

quoted

quoted

      br_netfilter_rtable_init(br);

diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
index 90e985b..edeb92d 100644
--- a/net/bridge/br_input.c
+++ b/net/bridge/br_input.c

@@ -43,6 +43,16 @@ static int br_pass_frame_up(struct sk_buff *skb)

                     netif_receive_skb);
 }

+static inline bool br_pae_forward(struct net_bridge *br, __be16 proto)
+{
+     return br->pae_forward == BR_PAE_FORWARD && proto == htons(ETH_P_PAE);
+}
+
+static inline bool br_pae_drop(struct net_bridge *br, __be16 proto)
+{
+     return br->pae_forward == BR_PAE_DEFAULT && proto == htons(ETH_P_PAE);
+}

Since only used one place, the extra wrappers aren't helping.

I thought they helped readability, but certainly for performance we
should only be doing each check once in a single place.  Again happy
to change.

quoted

quoted

 /* note: already called with rcu_read_lock */
 int br_handle_frame_finish(struct sk_buff *skb)
 {

@@ -98,6 +108,10 @@ int br_handle_frame_finish(struct sk_buff *skb)

      }

      if (skb) {
+             /* Prevent Crosstalk (IEEE Std 802.1X-2001 C.3.3) */
+             if (unlikely(br_pae_drop(br, skb->protocol)))
+                     goto drop;
+

Referencing standard is good, but perhaps explaining what that means.

ok

quoted

Since these are multicast frames, will it ever reach this point.
This point is reached for unicast frames that are not local.

yes, think of it as a bug fix rather than part of new functionality

quoted

And won't this change existing behavior since before this 802.1x unicast
frames would be forwarded.

Yes, that was my original motivation for making it a Kconfig setting,
so there would be no chance of regressions.  But keep in mind that
802.1x handshake must start with a multicast.  Its only if that
multicast is delivered that the reply can be unicast.  So any one
relying on the existing behaviour of forwarding unicast 802.1x must be
doing something very strange and non-standard.  I can't imagine what.
If there is a valid use case then they now have the simple workaround
of enabling pae forwarding.

quoted

quoted

              if (dst)
                      br_forward(dst->dst, skb, skb2);
              else

@@ -166,6 +180,10 @@ struct sk_buff *br_handle_frame(struct sk_buff *skb)

              if (p->br->stp_enabled == BR_NO_STP && dest[5] == 0)
                      goto forward;

+             /* Check if PAE frame should be forwarded */
+             if (br_pae_forward(p->br, skb->protocol))
+                     goto forward;
+
              if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev,
                          NULL, br_handle_local_finish))
                      return NULL;    /* frame consumed by filter */

diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index 4e1b620..683c057 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h

@@ -244,6 +244,11 @@ struct net_bridge

      struct timer_list               multicast_query_timer;
 #endif

+     enum {
+             BR_PAE_DEFAULT,         /* 802.1x frames consumed by bridge */
+             BR_PAE_FORWARD,         /* 802.1x frames forwarded by bridge */
+     } pae_forward;
+
      struct timer_list               hello_timer;
      struct timer_list               tcn_timer;
      struct timer_list               topology_change_timer;

diff --git a/net/bridge/br_sysfs_br.c b/net/bridge/br_sysfs_br.c
index 5c1e555..9bdbc84 100644
--- a/net/bridge/br_sysfs_br.c
+++ b/net/bridge/br_sysfs_br.c

@@ -679,6 +679,31 @@ static DEVICE_ATTR(nf_call_arptables, S_IRUGO | S_IWUSR,

                 show_nf_call_arptables, store_nf_call_arptables);
 #endif

+static ssize_t show_pae_forward(struct device *d, struct
device_attribute *attr,
+                             char *buf)
+{
+     struct net_bridge *br = to_bridge(d);
+     return sprintf(buf, "%d\n", br->pae_forward);
+}
+
+static int set_pae_forward(struct net_bridge *br, unsigned long val)
+{
+     if (val > BR_PAE_FORWARD)
+             return -EINVAL;
+
+     br->pae_forward = val;
+     return 0;
+}
+
+static ssize_t store_pae_forward(struct device *d,
+                              struct device_attribute *attr, const char *buf,
+                              size_t len)
+{
+     return store_bridge_parm(d, buf, len, set_pae_forward);
+}
+static DEVICE_ATTR(pae_forward, S_IRUGO | S_IWUSR, show_pae_forward,
+                store_pae_forward);
+
 static struct attribute *bridge_attrs[] = {
      &dev_attr_forward_delay.attr,
      &dev_attr_hello_time.attr,

@@ -698,6 +723,7 @@ static struct attribute *bridge_attrs[] = {

      &dev_attr_gc_timer.attr,
      &dev_attr_group_addr.attr,
      &dev_attr_flush.attr,
+     &dev_attr_pae_forward.attr,
 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
      &dev_attr_multicast_router.attr,
      &dev_attr_multicast_snooping.attr,