linux/net/bridge/br_stp_bpdu.c
Eric W. Biederman 0c4b51f005 netfilter: Pass net into okfn
This is immediately motivated by the bridge code that chains functions that
call into netfilter.  Without passing net into the okfns the bridge code would
need to guess about the best expression for the network namespace to process
packets in.

As net is frequently one of the first things computed in continuation functions
after netfilter has done it's job passing in the desired network namespace is in
many cases a code simplification.

To support this change the function dst_output_okfn is introduced to
simplify passing dst_output as an okfn.  For the moment dst_output_okfn
just silently drops the struct net.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-09-17 17:18:37 -07:00

249 lines
5.8 KiB
C

/*
* Spanning tree protocol; BPDU handling
* Linux ethernet bridge
*
* Authors:
* Lennert Buytenhek <buytenh@gnu.org>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/kernel.h>
#include <linux/netfilter_bridge.h>
#include <linux/etherdevice.h>
#include <linux/llc.h>
#include <linux/slab.h>
#include <linux/pkt_sched.h>
#include <net/net_namespace.h>
#include <net/llc.h>
#include <net/llc_pdu.h>
#include <net/stp.h>
#include <asm/unaligned.h>
#include "br_private.h"
#include "br_private_stp.h"
#define STP_HZ 256
#define LLC_RESERVE sizeof(struct llc_pdu_un)
static int br_send_bpdu_finish(struct net *net, struct sock *sk,
struct sk_buff *skb)
{
return dev_queue_xmit(skb);
}
static void br_send_bpdu(struct net_bridge_port *p,
const unsigned char *data, int length)
{
struct sk_buff *skb;
skb = dev_alloc_skb(length+LLC_RESERVE);
if (!skb)
return;
skb->dev = p->dev;
skb->protocol = htons(ETH_P_802_2);
skb->priority = TC_PRIO_CONTROL;
skb_reserve(skb, LLC_RESERVE);
memcpy(__skb_put(skb, length), data, length);
llc_pdu_header_init(skb, LLC_PDU_TYPE_U, LLC_SAP_BSPAN,
LLC_SAP_BSPAN, LLC_PDU_CMD);
llc_pdu_init_as_ui_cmd(skb);
llc_mac_hdr_init(skb, p->dev->dev_addr, p->br->group_addr);
skb_reset_mac_header(skb);
NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_OUT,
dev_net(p->dev), NULL, skb, NULL, skb->dev,
br_send_bpdu_finish);
}
static inline void br_set_ticks(unsigned char *dest, int j)
{
unsigned long ticks = (STP_HZ * j)/ HZ;
put_unaligned_be16(ticks, dest);
}
static inline int br_get_ticks(const unsigned char *src)
{
unsigned long ticks = get_unaligned_be16(src);
return DIV_ROUND_UP(ticks * HZ, STP_HZ);
}
/* called under bridge lock */
void br_send_config_bpdu(struct net_bridge_port *p, struct br_config_bpdu *bpdu)
{
unsigned char buf[35];
if (p->br->stp_enabled != BR_KERNEL_STP)
return;
buf[0] = 0;
buf[1] = 0;
buf[2] = 0;
buf[3] = BPDU_TYPE_CONFIG;
buf[4] = (bpdu->topology_change ? 0x01 : 0) |
(bpdu->topology_change_ack ? 0x80 : 0);
buf[5] = bpdu->root.prio[0];
buf[6] = bpdu->root.prio[1];
buf[7] = bpdu->root.addr[0];
buf[8] = bpdu->root.addr[1];
buf[9] = bpdu->root.addr[2];
buf[10] = bpdu->root.addr[3];
buf[11] = bpdu->root.addr[4];
buf[12] = bpdu->root.addr[5];
buf[13] = (bpdu->root_path_cost >> 24) & 0xFF;
buf[14] = (bpdu->root_path_cost >> 16) & 0xFF;
buf[15] = (bpdu->root_path_cost >> 8) & 0xFF;
buf[16] = bpdu->root_path_cost & 0xFF;
buf[17] = bpdu->bridge_id.prio[0];
buf[18] = bpdu->bridge_id.prio[1];
buf[19] = bpdu->bridge_id.addr[0];
buf[20] = bpdu->bridge_id.addr[1];
buf[21] = bpdu->bridge_id.addr[2];
buf[22] = bpdu->bridge_id.addr[3];
buf[23] = bpdu->bridge_id.addr[4];
buf[24] = bpdu->bridge_id.addr[5];
buf[25] = (bpdu->port_id >> 8) & 0xFF;
buf[26] = bpdu->port_id & 0xFF;
br_set_ticks(buf+27, bpdu->message_age);
br_set_ticks(buf+29, bpdu->max_age);
br_set_ticks(buf+31, bpdu->hello_time);
br_set_ticks(buf+33, bpdu->forward_delay);
br_send_bpdu(p, buf, 35);
}
/* called under bridge lock */
void br_send_tcn_bpdu(struct net_bridge_port *p)
{
unsigned char buf[4];
if (p->br->stp_enabled != BR_KERNEL_STP)
return;
buf[0] = 0;
buf[1] = 0;
buf[2] = 0;
buf[3] = BPDU_TYPE_TCN;
br_send_bpdu(p, buf, 4);
}
/*
* Called from llc.
*
* NO locks, but rcu_read_lock
*/
void br_stp_rcv(const struct stp_proto *proto, struct sk_buff *skb,
struct net_device *dev)
{
const unsigned char *dest = eth_hdr(skb)->h_dest;
struct net_bridge_port *p;
struct net_bridge *br;
const unsigned char *buf;
if (!pskb_may_pull(skb, 4))
goto err;
/* compare of protocol id and version */
buf = skb->data;
if (buf[0] != 0 || buf[1] != 0 || buf[2] != 0)
goto err;
p = br_port_get_check_rcu(dev);
if (!p)
goto err;
br = p->br;
spin_lock(&br->lock);
if (br->stp_enabled != BR_KERNEL_STP)
goto out;
if (!(br->dev->flags & IFF_UP))
goto out;
if (p->state == BR_STATE_DISABLED)
goto out;
if (!ether_addr_equal(dest, br->group_addr))
goto out;
if (p->flags & BR_BPDU_GUARD) {
br_notice(br, "BPDU received on blocked port %u(%s)\n",
(unsigned int) p->port_no, p->dev->name);
br_stp_disable_port(p);
goto out;
}
buf = skb_pull(skb, 3);
if (buf[0] == BPDU_TYPE_CONFIG) {
struct br_config_bpdu bpdu;
if (!pskb_may_pull(skb, 32))
goto out;
buf = skb->data;
bpdu.topology_change = (buf[1] & 0x01) ? 1 : 0;
bpdu.topology_change_ack = (buf[1] & 0x80) ? 1 : 0;
bpdu.root.prio[0] = buf[2];
bpdu.root.prio[1] = buf[3];
bpdu.root.addr[0] = buf[4];
bpdu.root.addr[1] = buf[5];
bpdu.root.addr[2] = buf[6];
bpdu.root.addr[3] = buf[7];
bpdu.root.addr[4] = buf[8];
bpdu.root.addr[5] = buf[9];
bpdu.root_path_cost =
(buf[10] << 24) |
(buf[11] << 16) |
(buf[12] << 8) |
buf[13];
bpdu.bridge_id.prio[0] = buf[14];
bpdu.bridge_id.prio[1] = buf[15];
bpdu.bridge_id.addr[0] = buf[16];
bpdu.bridge_id.addr[1] = buf[17];
bpdu.bridge_id.addr[2] = buf[18];
bpdu.bridge_id.addr[3] = buf[19];
bpdu.bridge_id.addr[4] = buf[20];
bpdu.bridge_id.addr[5] = buf[21];
bpdu.port_id = (buf[22] << 8) | buf[23];
bpdu.message_age = br_get_ticks(buf+24);
bpdu.max_age = br_get_ticks(buf+26);
bpdu.hello_time = br_get_ticks(buf+28);
bpdu.forward_delay = br_get_ticks(buf+30);
if (bpdu.message_age > bpdu.max_age) {
if (net_ratelimit())
br_notice(p->br,
"port %u config from %pM"
" (message_age %ul > max_age %ul)\n",
p->port_no,
eth_hdr(skb)->h_source,
bpdu.message_age, bpdu.max_age);
goto out;
}
br_received_config_bpdu(p, &bpdu);
} else if (buf[0] == BPDU_TYPE_TCN) {
br_received_tcn_bpdu(p);
}
out:
spin_unlock(&br->lock);
err:
kfree_skb(skb);
}