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linux/drivers/net/ifb.c
Willem de Bruijn bc31c905e9 net-tc: convert tc_from to tc_from_ingress and tc_redirected 
The tc_from field fulfills two roles. It encodes whether a packet was
redirected by an act_mirred device and, if so, whether act_mirred was
called on ingress or egress. Split it into separate fields.

The information is needed by the special IFB loop, where packets are
taken out of the normal path by act_mirred, forwarded to IFB, then
reinjected at their original location (ingress or egress) by IFB.

The IFB device cannot use skb->tc_at_ingress, because that may have
been overwritten as the packet travels from act_mirred to ifb_xmit,
when it passes through tc_classify on the IFB egress path. Cache this
value in skb->tc_from_ingress.

That field is valid only if a packet arriving at ifb_xmit came from
act_mirred. Other packets can be crafted to reach ifb_xmit. These
must be dropped. Set tc_redirected on redirection and drop all packets
that do not have this bit set.

Both fields are set only on cloned skbs in tc actions, so original
packet sources do not have to clear the bit when reusing packets
(notably, pktgen and octeon).

Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-08 20:58:52 -05:00

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/* drivers/net/ifb.c:
The purpose of this driver is to provide a device that allows
for sharing of resources:
1) qdiscs/policies that are per device as opposed to system wide.
ifb allows for a device which can be redirected to thus providing
an impression of sharing.
2) Allows for queueing incoming traffic for shaping instead of
dropping.
The original concept is based on what is known as the IMQ
driver initially written by Martin Devera, later rewritten
by Patrick McHardy and then maintained by Andre Correa.
You need the tc action mirror or redirect to feed this device
packets.
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.
Authors: Jamal Hadi Salim (2005)
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/moduleparam.h>
#include <net/pkt_sched.h>
#include <net/net_namespace.h>
#define TX_Q_LIMIT 32
struct ifb_q_private {
struct net_device *dev;
struct tasklet_struct ifb_tasklet;
int tasklet_pending;
int txqnum;
struct sk_buff_head rq;
u64 rx_packets;
u64 rx_bytes;
struct u64_stats_sync rsync;
struct u64_stats_sync tsync;
u64 tx_packets;
u64 tx_bytes;
struct sk_buff_head tq;
} ____cacheline_aligned_in_smp;
struct ifb_dev_private {
struct ifb_q_private *tx_private;
};
static netdev_tx_t ifb_xmit(struct sk_buff *skb, struct net_device *dev);
static int ifb_open(struct net_device *dev);
static int ifb_close(struct net_device *dev);
static void ifb_ri_tasklet(unsigned long _txp)
{
struct ifb_q_private *txp = (struct ifb_q_private *)_txp;
struct netdev_queue *txq;
struct sk_buff *skb;
txq = netdev_get_tx_queue(txp->dev, txp->txqnum);
skb = skb_peek(&txp->tq);
if (!skb) {
if (!__netif_tx_trylock(txq))
goto resched;
skb_queue_splice_tail_init(&txp->rq, &txp->tq);
__netif_tx_unlock(txq);
}
while ((skb = __skb_dequeue(&txp->tq)) != NULL) {
skb->tc_redirected = 0;
skb->tc_skip_classify = 1;
u64_stats_update_begin(&txp->tsync);
txp->tx_packets++;
txp->tx_bytes += skb->len;
u64_stats_update_end(&txp->tsync);
rcu_read_lock();
skb->dev = dev_get_by_index_rcu(dev_net(txp->dev), skb->skb_iif);
if (!skb->dev) {
rcu_read_unlock();
dev_kfree_skb(skb);
txp->dev->stats.tx_dropped++;
if (skb_queue_len(&txp->tq) != 0)
goto resched;
break;
}
rcu_read_unlock();
skb->skb_iif = txp->dev->ifindex;
if (!skb->tc_from_ingress) {
dev_queue_xmit(skb);
} else {
skb_pull(skb, skb->mac_len);
netif_receive_skb(skb);
}
}
if (__netif_tx_trylock(txq)) {
skb = skb_peek(&txp->rq);
if (!skb) {
txp->tasklet_pending = 0;
if (netif_tx_queue_stopped(txq))
netif_tx_wake_queue(txq);
} else {
__netif_tx_unlock(txq);
goto resched;
}
__netif_tx_unlock(txq);
} else {
resched:
txp->tasklet_pending = 1;
tasklet_schedule(&txp->ifb_tasklet);
}
}
static void ifb_stats64(struct net_device *dev,
struct rtnl_link_stats64 *stats)
{
struct ifb_dev_private *dp = netdev_priv(dev);
struct ifb_q_private *txp = dp->tx_private;
unsigned int start;
u64 packets, bytes;
int i;
for (i = 0; i < dev->num_tx_queues; i++,txp++) {
do {
start = u64_stats_fetch_begin_irq(&txp->rsync);
packets = txp->rx_packets;
bytes = txp->rx_bytes;
} while (u64_stats_fetch_retry_irq(&txp->rsync, start));
stats->rx_packets += packets;
stats->rx_bytes += bytes;
do {
start = u64_stats_fetch_begin_irq(&txp->tsync);
packets = txp->tx_packets;
bytes = txp->tx_bytes;
} while (u64_stats_fetch_retry_irq(&txp->tsync, start));
stats->tx_packets += packets;
stats->tx_bytes += bytes;
}
stats->rx_dropped = dev->stats.rx_dropped;
stats->tx_dropped = dev->stats.tx_dropped;
}
static int ifb_dev_init(struct net_device *dev)
{
struct ifb_dev_private *dp = netdev_priv(dev);
struct ifb_q_private *txp;
int i;
txp = kcalloc(dev->num_tx_queues, sizeof(*txp), GFP_KERNEL);
if (!txp)
return -ENOMEM;
dp->tx_private = txp;
for (i = 0; i < dev->num_tx_queues; i++,txp++) {
txp->txqnum = i;
txp->dev = dev;
__skb_queue_head_init(&txp->rq);
__skb_queue_head_init(&txp->tq);
u64_stats_init(&txp->rsync);
u64_stats_init(&txp->tsync);
tasklet_init(&txp->ifb_tasklet, ifb_ri_tasklet,
(unsigned long)txp);
netif_tx_start_queue(netdev_get_tx_queue(dev, i));
}
return 0;
}
static const struct net_device_ops ifb_netdev_ops = {
.ndo_open = ifb_open,
.ndo_stop = ifb_close,
.ndo_get_stats64 = ifb_stats64,
.ndo_start_xmit = ifb_xmit,
.ndo_validate_addr = eth_validate_addr,
.ndo_init = ifb_dev_init,
};
#define IFB_FEATURES (NETIF_F_HW_CSUM | NETIF_F_SG | NETIF_F_FRAGLIST | \
NETIF_F_TSO_ECN | NETIF_F_TSO | NETIF_F_TSO6 | \
NETIF_F_GSO_ENCAP_ALL | \
NETIF_F_HIGHDMA | NETIF_F_HW_VLAN_CTAG_TX | \
NETIF_F_HW_VLAN_STAG_TX)
static void ifb_dev_free(struct net_device *dev)
{
struct ifb_dev_private *dp = netdev_priv(dev);
struct ifb_q_private *txp = dp->tx_private;
int i;
for (i = 0; i < dev->num_tx_queues; i++,txp++) {
tasklet_kill(&txp->ifb_tasklet);
__skb_queue_purge(&txp->rq);
__skb_queue_purge(&txp->tq);
}
kfree(dp->tx_private);
free_netdev(dev);
}
static void ifb_setup(struct net_device *dev)
{
/* Initialize the device structure. */
dev->netdev_ops = &ifb_netdev_ops;
/* Fill in device structure with ethernet-generic values. */
ether_setup(dev);
dev->tx_queue_len = TX_Q_LIMIT;
dev->features |= IFB_FEATURES;
dev->hw_features |= dev->features;
dev->hw_enc_features |= dev->features;
dev->vlan_features |= IFB_FEATURES & ~(NETIF_F_HW_VLAN_CTAG_TX |
NETIF_F_HW_VLAN_STAG_TX);
dev->flags |= IFF_NOARP;
dev->flags &= ~IFF_MULTICAST;
dev->priv_flags &= ~IFF_TX_SKB_SHARING;
netif_keep_dst(dev);
eth_hw_addr_random(dev);
dev->destructor = ifb_dev_free;
}
static netdev_tx_t ifb_xmit(struct sk_buff *skb, struct net_device *dev)
{
struct ifb_dev_private *dp = netdev_priv(dev);
struct ifb_q_private *txp = dp->tx_private + skb_get_queue_mapping(skb);
u64_stats_update_begin(&txp->rsync);
txp->rx_packets++;
txp->rx_bytes += skb->len;
u64_stats_update_end(&txp->rsync);
if (!skb->tc_redirected || !skb->skb_iif) {
dev_kfree_skb(skb);
dev->stats.rx_dropped++;
return NETDEV_TX_OK;
}
if (skb_queue_len(&txp->rq) >= dev->tx_queue_len)
netif_tx_stop_queue(netdev_get_tx_queue(dev, txp->txqnum));
__skb_queue_tail(&txp->rq, skb);
if (!txp->tasklet_pending) {
txp->tasklet_pending = 1;
tasklet_schedule(&txp->ifb_tasklet);
}
return NETDEV_TX_OK;
}
static int ifb_close(struct net_device *dev)
{
netif_tx_stop_all_queues(dev);
return 0;
}
static int ifb_open(struct net_device *dev)
{
netif_tx_start_all_queues(dev);
return 0;
}
static int ifb_validate(struct nlattr *tb[], struct nlattr *data[])
{
if (tb[IFLA_ADDRESS]) {
if (nla_len(tb[IFLA_ADDRESS]) != ETH_ALEN)
return -EINVAL;
if (!is_valid_ether_addr(nla_data(tb[IFLA_ADDRESS])))
return -EADDRNOTAVAIL;
}
return 0;
}
static struct rtnl_link_ops ifb_link_ops __read_mostly = {
.kind = "ifb",
.priv_size = sizeof(struct ifb_dev_private),
.setup = ifb_setup,
.validate = ifb_validate,
};
/* Number of ifb devices to be set up by this module.
* Note that these legacy devices have one queue.
* Prefer something like : ip link add ifb10 numtxqueues 8 type ifb
*/
static int numifbs = 2;
module_param(numifbs, int, 0);
MODULE_PARM_DESC(numifbs, "Number of ifb devices");
static int __init ifb_init_one(int index)
{
struct net_device *dev_ifb;
int err;
dev_ifb = alloc_netdev(sizeof(struct ifb_dev_private), "ifb%d",
NET_NAME_UNKNOWN, ifb_setup);
if (!dev_ifb)
return -ENOMEM;
dev_ifb->rtnl_link_ops = &ifb_link_ops;
err = register_netdevice(dev_ifb);
if (err < 0)
goto err;
return 0;
err:
free_netdev(dev_ifb);
return err;
}
static int __init ifb_init_module(void)
{
int i, err;
rtnl_lock();
err = __rtnl_link_register(&ifb_link_ops);
if (err < 0)
goto out;
for (i = 0; i < numifbs && !err; i++) {
err = ifb_init_one(i);
cond_resched();
}
if (err)
__rtnl_link_unregister(&ifb_link_ops);
out:
rtnl_unlock();
return err;
}
static void __exit ifb_cleanup_module(void)
{
rtnl_link_unregister(&ifb_link_ops);
}
module_init(ifb_init_module);
module_exit(ifb_cleanup_module);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Jamal Hadi Salim");
MODULE_ALIAS_RTNL_LINK("ifb");
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