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