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Message-ID: <5dd9e4e8-466d-47dc-1257-09823ba783b9@cumulusnetworks.com>
Date: Sat, 30 Sep 2017 01:11:08 +0300
From: Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
To: Stephen Hemminger <stephen@...workplumber.org>
Cc: netdev@...r.kernel.org, roopa@...ulusnetworks.com,
bridge@...ts.linux-foundation.org
Subject: Re: [PATCH net-next] net: bridge: add per-port group_fwd_mask with
less restrictions
On 30/09/17 00:51, Stephen Hemminger wrote:
> On Sat, 30 Sep 2017 00:01:24 +0300
> Nikolay Aleksandrov <nikolay@...ulusnetworks.com> wrote:
>
>> On 29/09/17 18:14, Stephen Hemminger wrote:
>>> On Wed, 27 Sep 2017 16:12:44 +0300
>>> Nikolay Aleksandrov <nikolay@...ulusnetworks.com> wrote:
>>>
>>>> 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 <nikolay@...ulusnetworks.com>
>>>
>>> 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.
>
I get the motivation, but it does not have to be stupid. It may be 802.1q in q, not 802.1ad
where STP is already forwarded by default, or it may be that the port is participating
in a different STP. Wouldn't be enough to warn the user that STP forwarding was enabled
for that port, instead of forcing it off and having it only for 802.1ad ?
Later when we upstream 802.1Q in q patches we'll have to work around that anyway.
> From 16c42db4852234c13288922c1bffbf7650e08434 Mon Sep 17 00:00:00 2001
> From: Stephen Hemminger <sthemmin@...rosoft.com>
> 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")
What if the user requested explicitly to forward these frames from that port ?
> Signed-off-by: Stephen Hemminger <stephen@...workplumber.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);
>
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