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linux-hardened/drivers/net/loopback.c
Eric W. Biederman ce286d3273 [NET]: Implement network device movement between namespaces 
This patch introduces NETIF_F_NETNS_LOCAL a flag to indicate
a network device is local to a single network namespace and
should never be moved.  Useful for pseudo devices that we
need an instance in each network namespace (like the loopback
device) and for any device we find that cannot handle multiple
network namespaces so we may trap them in the initial network
namespace.

This patch introduces the function dev_change_net_namespace
a function used to move a network device from one network
namespace to another.  To the network device nothing
special appears to happen, to the components of the network
stack it appears as if the network device was unregistered
in the network namespace it is in, and a new device
was registered in the network namespace the device
was moved to.

This patch sets up a namespace device destructor that
upon the exit of a network namespace moves all of the
movable network devices  to the initial network namespace
so they are not lost.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-10-10 16:49:12 -07:00

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/*
* 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.
*
* 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.
*/
#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/init.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/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>
struct pcpu_lstats {
unsigned long packets;
unsigned long bytes;
};
static DEFINE_PER_CPU(struct pcpu_lstats, pcpu_lstats);
#define LOOPBACK_OVERHEAD (128 + MAX_HEADER + 16 + 16)
/* KISS: just allocate small chunks and copy bits.
*
* So, in fact, this is documentation, explaining what we expect
* of largesending device modulo TCP checksum, which is ignored for loopback.
*/
#ifdef LOOPBACK_TSO
static void emulate_large_send_offload(struct sk_buff *skb)
{
struct iphdr *iph = ip_hdr(skb);
struct tcphdr *th = (struct tcphdr *)(skb_network_header(skb) +
(iph->ihl * 4));
unsigned int doffset = (iph->ihl + th->doff) * 4;
unsigned int mtu = skb_shinfo(skb)->gso_size + doffset;
unsigned int offset = 0;
u32 seq = ntohl(th->seq);
u16 id = ntohs(iph->id);
while (offset + doffset < skb->len) {
unsigned int frag_size = min(mtu, skb->len - offset) - doffset;
struct sk_buff *nskb = alloc_skb(mtu + 32, GFP_ATOMIC);
if (!nskb)
break;
skb_reserve(nskb, 32);
skb_set_mac_header(nskb, -ETH_HLEN);
skb_reset_network_header(nskb);
iph = ip_hdr(nskb);
skb_copy_to_linear_data(nskb, skb_network_header(skb),
doffset);
if (skb_copy_bits(skb,
doffset + offset,
nskb->data + doffset,
frag_size))
BUG();
skb_put(nskb, doffset + frag_size);
nskb->ip_summed = CHECKSUM_UNNECESSARY;
nskb->dev = skb->dev;
nskb->priority = skb->priority;
nskb->protocol = skb->protocol;
nskb->dst = dst_clone(skb->dst);
memcpy(nskb->cb, skb->cb, sizeof(skb->cb));
nskb->pkt_type = skb->pkt_type;
th = (struct tcphdr *)(skb_network_header(nskb) + iph->ihl * 4);
iph->tot_len = htons(frag_size + doffset);
iph->id = htons(id);
iph->check = 0;
iph->check = ip_fast_csum((unsigned char *) iph, iph->ihl);
th->seq = htonl(seq);
if (offset + doffset + frag_size < skb->len)
th->fin = th->psh = 0;
netif_rx(nskb);
offset += frag_size;
seq += frag_size;
id++;
}
dev_kfree_skb(skb);
}
#endif /* LOOPBACK_TSO */
/*
* The higher levels take care of making this non-reentrant (it's
* called with bh's disabled).
*/
static int loopback_xmit(struct sk_buff *skb, struct net_device *dev)
{
struct pcpu_lstats *lb_stats;
skb_orphan(skb);
skb->protocol = eth_type_trans(skb,dev);
#ifndef LOOPBACK_MUST_CHECKSUM
skb->ip_summed = CHECKSUM_UNNECESSARY;
#endif
#ifdef LOOPBACK_TSO
if (skb_is_gso(skb)) {
BUG_ON(skb->protocol != htons(ETH_P_IP));
BUG_ON(ip_hdr(skb)->protocol != IPPROTO_TCP);
emulate_large_send_offload(skb);
return 0;
}
#endif
dev->last_rx = jiffies;
/* it's OK to use __get_cpu_var() because BHs are off */
lb_stats = &__get_cpu_var(pcpu_lstats);
lb_stats->bytes += skb->len;
lb_stats->packets++;
netif_rx(skb);
return 0;
}
static struct net_device_stats *get_stats(struct net_device *dev)
{
struct net_device_stats *stats = &dev->stats;
unsigned long bytes = 0;
unsigned long packets = 0;
int i;
for_each_possible_cpu(i) {
const struct pcpu_lstats *lb_stats;
lb_stats = &per_cpu(pcpu_lstats, i);
bytes += lb_stats->bytes;
packets += lb_stats->packets;
}
stats->rx_packets = packets;
stats->tx_packets = packets;
stats->rx_bytes = bytes;
stats->tx_bytes = bytes;
return stats;
}
static u32 always_on(struct net_device *dev)
{
return 1;
}
static const struct ethtool_ops loopback_ethtool_ops = {
.get_link = always_on,
.get_tso = ethtool_op_get_tso,
.set_tso = ethtool_op_set_tso,
.get_tx_csum = always_on,
.get_sg = always_on,
.get_rx_csum = always_on,
};
/*
* The loopback device is special. There is only one instance and
* it is statically allocated. Don't do this for other devices.
*/
struct net_device loopback_dev = {
.name = "lo",
.get_stats = &get_stats,
.mtu = (16 * 1024) + 20 + 20 + 12,
.hard_start_xmit = loopback_xmit,
.hard_header = eth_header,
.hard_header_cache = eth_header_cache,
.header_cache_update = eth_header_cache_update,
.hard_header_len = ETH_HLEN, /* 14 */
.addr_len = ETH_ALEN, /* 6 */
.tx_queue_len = 0,
.type = ARPHRD_LOOPBACK, /* 0x0001*/
.rebuild_header = eth_rebuild_header,
.flags = IFF_LOOPBACK,
.features = NETIF_F_SG | NETIF_F_FRAGLIST
#ifdef LOOPBACK_TSO
| NETIF_F_TSO
#endif
| NETIF_F_NO_CSUM | NETIF_F_HIGHDMA
| NETIF_F_LLTX
| NETIF_F_NETNS_LOCAL,
.ethtool_ops = &loopback_ethtool_ops,
};
/* Setup and register the loopback device. */
static int __init loopback_init(void)
{
int err = register_netdev(&loopback_dev);
if (err)
panic("loopback: Failed to register netdevice: %d\n", err);
return err;
};
module_init(loopback_init);
EXPORT_SYMBOL(loopback_dev);
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