281 lines
7.1 KiB
C
281 lines
7.1 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* INET An implementation of the TCP/IP protocol suite for the LINUX
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* operating system. INET is implemented using the BSD Socket
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* interface as the means of communication with the user level.
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*
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* Pseudo-driver for the loopback interface.
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*
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* Version: @(#)loopback.c 1.0.4b 08/16/93
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*
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* Authors: Ross Biro
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* Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
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* Donald Becker, <becker@scyld.com>
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*
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* Alan Cox : Fixed oddments for NET3.014
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* Alan Cox : Rejig for NET3.029 snap #3
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* Alan Cox : Fixed NET3.029 bugs and sped up
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* Larry McVoy : Tiny tweak to double performance
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* Alan Cox : Backed out LMV's tweak - the linux mm
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* can't take it...
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* Michael Griffith: Don't bother computing the checksums
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* on packets received on the loopback
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* interface.
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* Alexey Kuznetsov: Potential hang under some extreme
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* cases removed.
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*/
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#include <linux/kernel.h>
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#include <linux/jiffies.h>
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#include <linux/module.h>
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#include <linux/interrupt.h>
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#include <linux/fs.h>
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#include <linux/types.h>
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#include <linux/string.h>
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#include <linux/socket.h>
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#include <linux/errno.h>
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#include <linux/fcntl.h>
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#include <linux/in.h>
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#include <linux/uaccess.h>
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#include <linux/io.h>
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#include <linux/inet.h>
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#include <linux/netdevice.h>
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#include <linux/etherdevice.h>
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#include <linux/skbuff.h>
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#include <linux/ethtool.h>
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#include <net/sch_generic.h>
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#include <net/sock.h>
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#include <net/checksum.h>
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#include <linux/if_ether.h> /* For the statistics structure. */
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#include <linux/if_arp.h> /* For ARPHRD_ETHER */
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#include <linux/ip.h>
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#include <linux/tcp.h>
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#include <linux/percpu.h>
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#include <linux/net_tstamp.h>
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#include <net/net_namespace.h>
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#include <linux/u64_stats_sync.h>
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/* blackhole_netdev - a device used for dsts that are marked expired!
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* This is global device (instead of per-net-ns) since it's not needed
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* to be per-ns and gets initialized at boot time.
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*/
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struct net_device *blackhole_netdev;
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EXPORT_SYMBOL(blackhole_netdev);
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/* The higher levels take care of making this non-reentrant (it's
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* called with bh's disabled).
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*/
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static netdev_tx_t loopback_xmit(struct sk_buff *skb,
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struct net_device *dev)
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{
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int len;
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skb_tx_timestamp(skb);
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/* do not fool net_timestamp_check() with various clock bases */
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skb_clear_tstamp(skb);
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skb_orphan(skb);
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/* Before queueing this packet to __netif_rx(),
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* make sure dst is refcounted.
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*/
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skb_dst_force(skb);
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skb->protocol = eth_type_trans(skb, dev);
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len = skb->len;
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if (likely(__netif_rx(skb) == NET_RX_SUCCESS))
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dev_lstats_add(dev, len);
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return NETDEV_TX_OK;
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}
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void dev_lstats_read(struct net_device *dev, u64 *packets, u64 *bytes)
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{
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int i;
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*packets = 0;
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*bytes = 0;
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for_each_possible_cpu(i) {
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const struct pcpu_lstats *lb_stats;
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u64 tbytes, tpackets;
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unsigned int start;
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lb_stats = per_cpu_ptr(dev->lstats, i);
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do {
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start = u64_stats_fetch_begin_irq(&lb_stats->syncp);
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tpackets = u64_stats_read(&lb_stats->packets);
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tbytes = u64_stats_read(&lb_stats->bytes);
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} while (u64_stats_fetch_retry_irq(&lb_stats->syncp, start));
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*bytes += tbytes;
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*packets += tpackets;
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}
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}
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EXPORT_SYMBOL(dev_lstats_read);
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static void loopback_get_stats64(struct net_device *dev,
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struct rtnl_link_stats64 *stats)
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{
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u64 packets, bytes;
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dev_lstats_read(dev, &packets, &bytes);
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stats->rx_packets = packets;
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stats->tx_packets = packets;
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stats->rx_bytes = bytes;
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stats->tx_bytes = bytes;
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}
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static u32 always_on(struct net_device *dev)
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{
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return 1;
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}
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static const struct ethtool_ops loopback_ethtool_ops = {
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.get_link = always_on,
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.get_ts_info = ethtool_op_get_ts_info,
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};
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static int loopback_dev_init(struct net_device *dev)
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{
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dev->lstats = netdev_alloc_pcpu_stats(struct pcpu_lstats);
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if (!dev->lstats)
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return -ENOMEM;
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return 0;
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}
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static void loopback_dev_free(struct net_device *dev)
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{
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dev_net(dev)->loopback_dev = NULL;
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free_percpu(dev->lstats);
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}
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static const struct net_device_ops loopback_ops = {
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.ndo_init = loopback_dev_init,
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.ndo_start_xmit = loopback_xmit,
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.ndo_get_stats64 = loopback_get_stats64,
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.ndo_set_mac_address = eth_mac_addr,
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};
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static void gen_lo_setup(struct net_device *dev,
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unsigned int mtu,
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const struct ethtool_ops *eth_ops,
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const struct header_ops *hdr_ops,
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const struct net_device_ops *dev_ops,
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void (*dev_destructor)(struct net_device *dev))
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{
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dev->mtu = mtu;
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dev->hard_header_len = ETH_HLEN; /* 14 */
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dev->min_header_len = ETH_HLEN; /* 14 */
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dev->addr_len = ETH_ALEN; /* 6 */
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dev->type = ARPHRD_LOOPBACK; /* 0x0001*/
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dev->flags = IFF_LOOPBACK;
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dev->priv_flags |= IFF_LIVE_ADDR_CHANGE | IFF_NO_QUEUE;
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netif_keep_dst(dev);
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dev->hw_features = NETIF_F_GSO_SOFTWARE;
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dev->features = NETIF_F_SG | NETIF_F_FRAGLIST
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| NETIF_F_GSO_SOFTWARE
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| NETIF_F_HW_CSUM
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| NETIF_F_RXCSUM
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| NETIF_F_SCTP_CRC
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| NETIF_F_HIGHDMA
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| NETIF_F_LLTX
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| NETIF_F_NETNS_LOCAL
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| NETIF_F_VLAN_CHALLENGED
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| NETIF_F_LOOPBACK;
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dev->ethtool_ops = eth_ops;
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dev->header_ops = hdr_ops;
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dev->netdev_ops = dev_ops;
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dev->needs_free_netdev = true;
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dev->priv_destructor = dev_destructor;
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netif_set_tso_max_size(dev, GSO_MAX_SIZE);
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}
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/* The loopback device is special. There is only one instance
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* per network namespace.
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*/
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static void loopback_setup(struct net_device *dev)
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{
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gen_lo_setup(dev, (64 * 1024), &loopback_ethtool_ops, ð_header_ops,
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&loopback_ops, loopback_dev_free);
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}
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/* Setup and register the loopback device. */
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static __net_init int loopback_net_init(struct net *net)
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{
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struct net_device *dev;
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int err;
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err = -ENOMEM;
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dev = alloc_netdev(0, "lo", NET_NAME_UNKNOWN, loopback_setup);
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if (!dev)
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goto out;
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dev_net_set(dev, net);
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err = register_netdev(dev);
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if (err)
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goto out_free_netdev;
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BUG_ON(dev->ifindex != LOOPBACK_IFINDEX);
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net->loopback_dev = dev;
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return 0;
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out_free_netdev:
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free_netdev(dev);
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out:
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if (net_eq(net, &init_net))
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panic("loopback: Failed to register netdevice: %d\n", err);
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return err;
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}
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/* Registered in net/core/dev.c */
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struct pernet_operations __net_initdata loopback_net_ops = {
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.init = loopback_net_init,
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};
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/* blackhole netdevice */
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static netdev_tx_t blackhole_netdev_xmit(struct sk_buff *skb,
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struct net_device *dev)
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{
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kfree_skb(skb);
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net_warn_ratelimited("%s(): Dropping skb.\n", __func__);
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return NETDEV_TX_OK;
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}
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static const struct net_device_ops blackhole_netdev_ops = {
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.ndo_start_xmit = blackhole_netdev_xmit,
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};
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/* This is a dst-dummy device used specifically for invalidated
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* DSTs and unlike loopback, this is not per-ns.
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*/
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static void blackhole_netdev_setup(struct net_device *dev)
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{
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gen_lo_setup(dev, ETH_MIN_MTU, NULL, NULL, &blackhole_netdev_ops, NULL);
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}
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/* Setup and register the blackhole_netdev. */
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static int __init blackhole_netdev_init(void)
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{
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blackhole_netdev = alloc_netdev(0, "blackhole_dev", NET_NAME_UNKNOWN,
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blackhole_netdev_setup);
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if (!blackhole_netdev)
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return -ENOMEM;
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rtnl_lock();
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dev_init_scheduler(blackhole_netdev);
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dev_activate(blackhole_netdev);
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rtnl_unlock();
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blackhole_netdev->flags |= IFF_UP | IFF_RUNNING;
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dev_net_set(blackhole_netdev, &init_net);
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return 0;
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}
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device_initcall(blackhole_netdev_init);
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