diff options
Diffstat (limited to 'drivers/net/loopback.c')
| -rw-r--r-- | drivers/net/loopback.c | 280 |
1 files changed, 280 insertions, 0 deletions
diff --git a/drivers/net/loopback.c b/drivers/net/loopback.c new file mode 100644 index 0000000000..f6d53e63ef --- /dev/null +++ b/drivers/net/loopback.c @@ -0,0 +1,280 @@ +// 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/sch_generic.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_clear_tstamp(skb); + + 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(&lb_stats->syncp); + tpackets = u64_stats_read(&lb_stats->packets); + tbytes = u64_stats_read(&lb_stats->bytes); + } while (u64_stats_fetch_retry(&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; + + netif_set_tso_max_size(dev, GSO_MAX_SIZE); +} + +/* 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); |