Re: [PATCH net-next] net: bridge: add per-port group_fwd_mask with less restrictions

On Sat, 30 Sep 2017 00:01:24 +0300
Nikolay Aleksandrov [off-list ref] wrote:

On 29/09/17 18:14, Stephen Hemminger wrote:

quoted

On Wed, 27 Sep 2017 16:12:44 +0300
Nikolay Aleksandrov [off-list ref] wrote:
  

quoted

We need to be able to transparently forward most link-local frames via
tunnels (e.g. vxlan, qinq). Currently the bridge's group_fwd_mask has a
mask which restricts the forwarding of STP and LACP, but we need to be able
to forward these over tunnels and control that forwarding on a per-port
basis thus add a new per-port group_fwd_mask option which only disallows
mac pause frames to be forwarded (they're always dropped anyway).
The patch does not change the current default situation - all of the others
are still restricted unless configured for forwarding.
We have successfully tested this patch with LACP and STP forwarding over
VxLAN and qinq tunnels.

Signed-off-by: Nikolay Aleksandrov <redacted>  

LACP is fine, but STP must not be forwarded if STP in user or kernel
mode is enabled.

Please update this patch or revert it.
  

The default has not changed, STP is still _not_ forwarded. It can be only if explicitly
requested by the user and that means the port might be participating in STP but not
the bridge's STP, that is explicitly forward all STP frames from that port.
I don't think we have to change anything.

You need to fail if user does something stupid. And DNR.

From 16c42db4852234c13288922c1bffbf7650e08434 Mon Sep 17 00:00:00 2001
From: Stephen Hemminger <redacted>
Date: Fri, 29 Sep 2017 14:48:17 -0700
Subject: [PATCH] bridge: check for attempt to forward STP PDU's with STP
 enabled

Move validation into set function and do not allow
configuring forwarding of STP packets if STP is enabled.

Fixes: 5af48b59f35c ("net: bridge: add per-port group_fwd_mask with less restrictions")
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 net/bridge/br_if.c       | 13 +++++++++++++
 net/bridge/br_netlink.c  |  6 +++---
 net/bridge/br_private.h  |  1 +
 net/bridge/br_sysfs_if.c |  6 +-----
 4 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
index f3aef22931ab..a30e12f76266 100644
--- a/net/bridge/br_if.c
+++ b/net/bridge/br_if.c

@@ -654,3 +654,16 @@ void br_port_flags_change(struct net_bridge_port *p, unsigned long mask)
 	if (mask & BR_AUTO_MASK)
 		nbp_update_port_count(br);
 }
+
+int br_set_group_fwd_mask(struct net_bridge_port *p, u16 fwd_mask)
+{
+	if (fwd_mask & BR_GROUPFWD_MACPAUSE)
+		return -EINVAL;
+
+	if ((fwd_mask & BR_GROUPFWD_STP) &&
+	    (p->br->stp_enabled != BR_NO_STP))
+		return -EINVAL;
+
+	p->group_fwd_mask = fwd_mask;
+	return 0;
+}

diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
index dea88a255d26..7b16819ecb59 100644
--- a/net/bridge/br_netlink.c
+++ b/net/bridge/br_netlink.c

@@ -780,9 +780,9 @@ static int br_setport(struct net_bridge_port *p, struct nlattr *tb[])
 	if (tb[IFLA_BRPORT_GROUP_FWD_MASK]) {
 		u16 fwd_mask = nla_get_u16(tb[IFLA_BRPORT_GROUP_FWD_MASK]);
 
-		if (fwd_mask & BR_GROUPFWD_MACPAUSE)
-			return -EINVAL;
-		p->group_fwd_mask = fwd_mask;
+		err = br_set_group_fwd_mask(p, fwd_mask);
+		if (err)
+			return err;
 	}
 
 	br_port_flags_change(p, old_flags ^ p->flags);

diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index 020c709a017f..734933bebb08 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h

@@ -573,6 +573,7 @@ netdev_features_t br_features_recompute(struct net_bridge *br,
 					netdev_features_t features);
 void br_port_flags_change(struct net_bridge_port *port, unsigned long mask);
 void br_manage_promisc(struct net_bridge *br);
+int br_set_group_fwd_mask(struct net_bridge_port *p, u16 mask);
 
 /* br_input.c */
 int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb);

diff --git a/net/bridge/br_sysfs_if.c b/net/bridge/br_sysfs_if.c
index 9110d5e56085..f5871be10b24 100644
--- a/net/bridge/br_sysfs_if.c
+++ b/net/bridge/br_sysfs_if.c

@@ -173,11 +173,7 @@ static ssize_t show_group_fwd_mask(struct net_bridge_port *p, char *buf)
 static int store_group_fwd_mask(struct net_bridge_port *p,
 				unsigned long v)
 {
-	if (v & BR_GROUPFWD_MACPAUSE)
-		return -EINVAL;
-	p->group_fwd_mask = v;
-
-	return 0;
+	return br_set_group_fwd_mask(p, v);
 }
 static BRPORT_ATTR(group_fwd_mask, S_IRUGO | S_IWUSR, show_group_fwd_mask,
 		   store_group_fwd_mask);

-- 
2.11.0