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-rw-r--r--drivers/net/loopback.c280
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, &eth_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);