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Date: Thu, 21 Nov 2013 15:28:09 -0800
From: Stephen Hemminger <stephen@...workplumber.org>
To: Glenn FEUNTEUN <glenn.feunteun@...ecom-bretagne.eu>
Cc: netdev@...r.kernel.org
Subject: Re: [PATCH 0/1] Bridge mirroring function
On Thu, 21 Nov 2013 23:33:11 +0100 (CET)
Glenn FEUNTEUN <glenn.feunteun@...ecom-bretagne.eu> wrote:
> Hello
>
> I am working on a school project whose goal is to implement a traffic mirroring function inside bridge kernel module.
>
> I implemented the function that lets :
> - select the mirrored interface(s)
> - select ingress, egress or both traffic to be mirrored
> - select the output interface(s)
>
> Examples :
>
> a)
>
> brctl mirror br0 eth0 ingress
> brclt mirror br0 eth1 destination
>
> All incoming traffic on eth0 will be mirrored on eth1.
>
> b)
>
> brctl mirror br0 eth0 egress
> brclt mirror br0 eth1 destination
>
> All outgoing traffic from eth0 will be mirrored on eth1.
>
> c)
>
> brctl mirror br0 eth0 both
> brclt mirror br0 eth1 destination
>
> All incoming and outgoing traffic coming on or from eth0 will be mirrored on eth1.
>
> Following is the patch against kernel v3.12.
>
> I also implemented the userspace counterpart, I'll send the patch in another mail.
>
> Thank you for giving some feedback on the code and about its possible commit into kernel main tree.
>
>
> diff -urBb old/br_forward.c new/br_forward.c
> --- old/br_forward.c 2013-11-12 14:55:59.054134721 +0100
> +++ new/br_forward.c 2013-11-12 14:35:28.262134745 +0100
> @@ -62,6 +62,30 @@
>
> }
>
> +void br_mirror_xmit(const struct net_bridge_port *p, struct sk_buff *skb, u8 mask)
> +{
> + struct net_bridge_port *pos;
> + struct sk_buff *clone;
> + /* See if port has mirroring activated on incoming packet
> + ,outgoing packet or both depending on mask */
> + if(p->mirror_state & mask)
> + {
> + /* Look at each bridge port if one is a mirroring destination */
> +
> + list_for_each_entry(pos,&p->br->port_list,list)
> + {
> + if(pos->mirror_state & BR_MIRROR_DST)
> + {
> + /* Set clone device so it is sent on destination port */
> + clone = skb_copy(skb, GFP_ATOMIC);
> + clone->dev = pos->dev;
> + skb_push(clone, ETH_HLEN);
> + dev_queue_xmit(clone);
> + }
> + }
> + }
> +}
> +
> static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
> {
> skb = br_handle_vlan(to->br, nbp_get_vlan_info(to), skb);
> @@ -70,6 +94,8 @@
>
> skb->dev = to->dev;
>
> + br_mirror_xmit(to,skb,BR_MIRROR_TX);
> +
> if (unlikely(netpoll_tx_running(to->br->dev))) {
> if (packet_length(skb) > skb->dev->mtu && !skb_is_gso(skb))
> kfree_skb(skb);
> diff -urBb old/br_input.c new/br_input.c
> --- old/br_input.c 2013-11-12 14:55:59.054134721 +0100
> +++ new/br_input.c 2013-11-12 14:35:28.262134745 +0100
> @@ -216,6 +216,8 @@
> }
> }
>
> + br_mirror_xmit(p,skb,BR_MIRROR_RX);
> +
> forward:
> switch (p->state) {
> case BR_STATE_FORWARDING:
> diff -urBb old/br_private.h new/br_private.h
> --- old/br_private.h 2013-11-12 14:55:59.054134721 +0100
> +++ new/br_private.h 2013-11-13 15:57:33.668402893 +0100
> @@ -159,6 +159,12 @@
> u32 designated_cost;
> unsigned long designated_age;
>
> + /* Mirroring */
> +#define BR_MIRROR_RX 0x01
> +#define BR_MIRROR_TX 0x02
> +#define BR_MIRROR_DST 0x04
> + u8 mirror_state;
> +
> struct timer_list forward_delay_timer;
> struct timer_list hold_timer;
> struct timer_list message_age_timer;
> @@ -424,6 +430,7 @@
> bool unicast);
> extern void br_flood_forward(struct net_bridge *br, struct sk_buff *skb,
> struct sk_buff *skb2, bool unicast);
> +extern void br_mirror_xmit(const struct net_bridge_port *p, struct sk_buff *skb, u8 mask);
>
> /* br_if.c */
> extern void br_port_carrier_check(struct net_bridge_port *p);
> diff -urBb old/br_sysfs_if.c new/br_sysfs_if.c
> --- old/br_sysfs_if.c 2013-11-12 14:55:59.054134721 +0100
> +++ new/br_sysfs_if.c 2013-11-12 14:35:28.262134745 +0100
> @@ -161,6 +161,18 @@
> BRPORT_ATTR_FLAG(learning, BR_LEARNING);
> BRPORT_ATTR_FLAG(unicast_flood, BR_FLOOD);
>
> +static ssize_t show_mirror_state(struct net_bridge_port *p, char *buf)
> +{
> + return sprintf(buf, "%d\n", p->mirror_state);
> +}
> +static int store_mirror_state(struct net_bridge_port *p, unsigned long v)
> +{
> + p->mirror_state = v;
> + return 0;
> +}
> +static BRPORT_ATTR(mirror_state, S_IRUGO | S_IWUSR,
> + show_mirror_state, store_mirror_state);
> +
> #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
> static ssize_t show_multicast_router(struct net_bridge_port *p, char *buf)
> {
> @@ -199,6 +211,7 @@
> &brport_attr_root_block,
> &brport_attr_learning,
> &brport_attr_unicast_flood,
> + &brport_attr_mirror_state,
> #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
> &brport_attr_multicast_router,
> &brport_attr_multicast_fast_leave,
> --
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This already possible with 'tc mirred action'.
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