linux_dsm_epyc7002/net/l2tp/l2tp_eth.c
Guillaume Nault f026bc29a8 l2tp: pass tunnel pointer to ->session_create()
Using l2tp_tunnel_find() in pppol2tp_session_create() and
l2tp_eth_create() is racy, because no reference is held on the
returned session. These functions are only used to implement the
->session_create callback which is run by l2tp_nl_cmd_session_create().
Therefore searching for the parent tunnel isn't necessary because
l2tp_nl_cmd_session_create() already has a pointer to it and holds a
reference.

This patch modifies ->session_create()'s prototype to directly pass the
the parent tunnel as parameter, thus avoiding searching for it in
pppol2tp_session_create() and l2tp_eth_create().

Since we have to touch the ->session_create() call in
l2tp_nl_cmd_session_create(), let's also remove the useless conditional:
we know that ->session_create isn't NULL at this point because it's
already been checked earlier in this same function.

Finally, one might be tempted to think that the removed
l2tp_tunnel_find() calls were harmless because they would return the
same tunnel as the one held by l2tp_nl_cmd_session_create() anyway.
But that tunnel might be removed and a new one created with same tunnel
Id before the l2tp_tunnel_find() call. In this case l2tp_tunnel_find()
would return the new tunnel which wouldn't be protected by the
reference held by l2tp_nl_cmd_session_create().

Fixes: 309795f4be ("l2tp: Add netlink control API for L2TP")
Fixes: d9e31d17ce ("l2tp: Add L2TP ethernet pseudowire support")
Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-09-03 11:04:21 -07:00

404 lines
9.6 KiB
C

/*
* L2TPv3 ethernet pseudowire driver
*
* Copyright (c) 2008,2009,2010 Katalix Systems Ltd
*
* 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.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/socket.h>
#include <linux/hash.h>
#include <linux/l2tp.h>
#include <linux/in.h>
#include <linux/etherdevice.h>
#include <linux/spinlock.h>
#include <net/sock.h>
#include <net/ip.h>
#include <net/icmp.h>
#include <net/udp.h>
#include <net/inet_common.h>
#include <net/inet_hashtables.h>
#include <net/tcp_states.h>
#include <net/protocol.h>
#include <net/xfrm.h>
#include <net/net_namespace.h>
#include <net/netns/generic.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/udp.h>
#include "l2tp_core.h"
/* Default device name. May be overridden by name specified by user */
#define L2TP_ETH_DEV_NAME "l2tpeth%d"
/* via netdev_priv() */
struct l2tp_eth {
struct net_device *dev;
struct sock *tunnel_sock;
struct l2tp_session *session;
struct list_head list;
atomic_long_t tx_bytes;
atomic_long_t tx_packets;
atomic_long_t tx_dropped;
atomic_long_t rx_bytes;
atomic_long_t rx_packets;
atomic_long_t rx_errors;
};
/* via l2tp_session_priv() */
struct l2tp_eth_sess {
struct net_device *dev;
};
/* per-net private data for this module */
static unsigned int l2tp_eth_net_id;
struct l2tp_eth_net {
struct list_head l2tp_eth_dev_list;
spinlock_t l2tp_eth_lock;
};
static inline struct l2tp_eth_net *l2tp_eth_pernet(struct net *net)
{
return net_generic(net, l2tp_eth_net_id);
}
static int l2tp_eth_dev_init(struct net_device *dev)
{
struct l2tp_eth *priv = netdev_priv(dev);
priv->dev = dev;
eth_hw_addr_random(dev);
eth_broadcast_addr(dev->broadcast);
netdev_lockdep_set_classes(dev);
return 0;
}
static void l2tp_eth_dev_uninit(struct net_device *dev)
{
struct l2tp_eth *priv = netdev_priv(dev);
struct l2tp_eth_net *pn = l2tp_eth_pernet(dev_net(dev));
spin_lock(&pn->l2tp_eth_lock);
list_del_init(&priv->list);
spin_unlock(&pn->l2tp_eth_lock);
dev_put(dev);
}
static int l2tp_eth_dev_xmit(struct sk_buff *skb, struct net_device *dev)
{
struct l2tp_eth *priv = netdev_priv(dev);
struct l2tp_session *session = priv->session;
unsigned int len = skb->len;
int ret = l2tp_xmit_skb(session, skb, session->hdr_len);
if (likely(ret == NET_XMIT_SUCCESS)) {
atomic_long_add(len, &priv->tx_bytes);
atomic_long_inc(&priv->tx_packets);
} else {
atomic_long_inc(&priv->tx_dropped);
}
return NETDEV_TX_OK;
}
static void l2tp_eth_get_stats64(struct net_device *dev,
struct rtnl_link_stats64 *stats)
{
struct l2tp_eth *priv = netdev_priv(dev);
stats->tx_bytes = (unsigned long) atomic_long_read(&priv->tx_bytes);
stats->tx_packets = (unsigned long) atomic_long_read(&priv->tx_packets);
stats->tx_dropped = (unsigned long) atomic_long_read(&priv->tx_dropped);
stats->rx_bytes = (unsigned long) atomic_long_read(&priv->rx_bytes);
stats->rx_packets = (unsigned long) atomic_long_read(&priv->rx_packets);
stats->rx_errors = (unsigned long) atomic_long_read(&priv->rx_errors);
}
static const struct net_device_ops l2tp_eth_netdev_ops = {
.ndo_init = l2tp_eth_dev_init,
.ndo_uninit = l2tp_eth_dev_uninit,
.ndo_start_xmit = l2tp_eth_dev_xmit,
.ndo_get_stats64 = l2tp_eth_get_stats64,
.ndo_set_mac_address = eth_mac_addr,
};
static struct device_type l2tpeth_type = {
.name = "l2tpeth",
};
static void l2tp_eth_dev_setup(struct net_device *dev)
{
SET_NETDEV_DEVTYPE(dev, &l2tpeth_type);
ether_setup(dev);
dev->priv_flags &= ~IFF_TX_SKB_SHARING;
dev->features |= NETIF_F_LLTX;
dev->netdev_ops = &l2tp_eth_netdev_ops;
dev->needs_free_netdev = true;
}
static void l2tp_eth_dev_recv(struct l2tp_session *session, struct sk_buff *skb, int data_len)
{
struct l2tp_eth_sess *spriv = l2tp_session_priv(session);
struct net_device *dev = spriv->dev;
struct l2tp_eth *priv = netdev_priv(dev);
if (session->debug & L2TP_MSG_DATA) {
unsigned int length;
length = min(32u, skb->len);
if (!pskb_may_pull(skb, length))
goto error;
pr_debug("%s: eth recv\n", session->name);
print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, skb->data, length);
}
if (!pskb_may_pull(skb, ETH_HLEN))
goto error;
secpath_reset(skb);
/* checksums verified by L2TP */
skb->ip_summed = CHECKSUM_NONE;
skb_dst_drop(skb);
nf_reset(skb);
if (dev_forward_skb(dev, skb) == NET_RX_SUCCESS) {
atomic_long_inc(&priv->rx_packets);
atomic_long_add(data_len, &priv->rx_bytes);
} else {
atomic_long_inc(&priv->rx_errors);
}
return;
error:
atomic_long_inc(&priv->rx_errors);
kfree_skb(skb);
}
static void l2tp_eth_delete(struct l2tp_session *session)
{
struct l2tp_eth_sess *spriv;
struct net_device *dev;
if (session) {
spriv = l2tp_session_priv(session);
dev = spriv->dev;
if (dev) {
unregister_netdev(dev);
spriv->dev = NULL;
module_put(THIS_MODULE);
}
}
}
#if IS_ENABLED(CONFIG_L2TP_DEBUGFS)
static void l2tp_eth_show(struct seq_file *m, void *arg)
{
struct l2tp_session *session = arg;
struct l2tp_eth_sess *spriv = l2tp_session_priv(session);
struct net_device *dev = spriv->dev;
seq_printf(m, " interface %s\n", dev->name);
}
#endif
static void l2tp_eth_adjust_mtu(struct l2tp_tunnel *tunnel,
struct l2tp_session *session,
struct net_device *dev)
{
unsigned int overhead = 0;
struct dst_entry *dst;
u32 l3_overhead = 0;
/* if the encap is UDP, account for UDP header size */
if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {
overhead += sizeof(struct udphdr);
dev->needed_headroom += sizeof(struct udphdr);
}
if (session->mtu != 0) {
dev->mtu = session->mtu;
dev->needed_headroom += session->hdr_len;
return;
}
lock_sock(tunnel->sock);
l3_overhead = kernel_sock_ip_overhead(tunnel->sock);
release_sock(tunnel->sock);
if (l3_overhead == 0) {
/* L3 Overhead couldn't be identified, this could be
* because tunnel->sock was NULL or the socket's
* address family was not IPv4 or IPv6,
* dev mtu stays at 1500.
*/
return;
}
/* Adjust MTU, factor overhead - underlay L3, overlay L2 hdr
* UDP overhead, if any, was already factored in above.
*/
overhead += session->hdr_len + ETH_HLEN + l3_overhead;
/* If PMTU discovery was enabled, use discovered MTU on L2TP device */
dst = sk_dst_get(tunnel->sock);
if (dst) {
/* dst_mtu will use PMTU if found, else fallback to intf MTU */
u32 pmtu = dst_mtu(dst);
if (pmtu != 0)
dev->mtu = pmtu;
dst_release(dst);
}
session->mtu = dev->mtu - overhead;
dev->mtu = session->mtu;
dev->needed_headroom += session->hdr_len;
}
static int l2tp_eth_create(struct net *net, struct l2tp_tunnel *tunnel,
u32 session_id, u32 peer_session_id,
struct l2tp_session_cfg *cfg)
{
unsigned char name_assign_type;
struct net_device *dev;
char name[IFNAMSIZ];
struct l2tp_session *session;
struct l2tp_eth *priv;
struct l2tp_eth_sess *spriv;
int rc;
struct l2tp_eth_net *pn;
if (cfg->ifname) {
strlcpy(name, cfg->ifname, IFNAMSIZ);
name_assign_type = NET_NAME_USER;
} else {
strcpy(name, L2TP_ETH_DEV_NAME);
name_assign_type = NET_NAME_ENUM;
}
session = l2tp_session_create(sizeof(*spriv), tunnel, session_id,
peer_session_id, cfg);
if (IS_ERR(session)) {
rc = PTR_ERR(session);
goto out;
}
dev = alloc_netdev(sizeof(*priv), name, name_assign_type,
l2tp_eth_dev_setup);
if (!dev) {
rc = -ENOMEM;
goto out_del_session;
}
dev_net_set(dev, net);
dev->min_mtu = 0;
dev->max_mtu = ETH_MAX_MTU;
l2tp_eth_adjust_mtu(tunnel, session, dev);
priv = netdev_priv(dev);
priv->dev = dev;
priv->session = session;
INIT_LIST_HEAD(&priv->list);
priv->tunnel_sock = tunnel->sock;
session->recv_skb = l2tp_eth_dev_recv;
session->session_close = l2tp_eth_delete;
#if IS_ENABLED(CONFIG_L2TP_DEBUGFS)
session->show = l2tp_eth_show;
#endif
spriv = l2tp_session_priv(session);
spriv->dev = dev;
rc = register_netdev(dev);
if (rc < 0)
goto out_del_dev;
__module_get(THIS_MODULE);
/* Must be done after register_netdev() */
strlcpy(session->ifname, dev->name, IFNAMSIZ);
dev_hold(dev);
pn = l2tp_eth_pernet(dev_net(dev));
spin_lock(&pn->l2tp_eth_lock);
list_add(&priv->list, &pn->l2tp_eth_dev_list);
spin_unlock(&pn->l2tp_eth_lock);
return 0;
out_del_dev:
free_netdev(dev);
spriv->dev = NULL;
out_del_session:
l2tp_session_delete(session);
out:
return rc;
}
static __net_init int l2tp_eth_init_net(struct net *net)
{
struct l2tp_eth_net *pn = net_generic(net, l2tp_eth_net_id);
INIT_LIST_HEAD(&pn->l2tp_eth_dev_list);
spin_lock_init(&pn->l2tp_eth_lock);
return 0;
}
static struct pernet_operations l2tp_eth_net_ops = {
.init = l2tp_eth_init_net,
.id = &l2tp_eth_net_id,
.size = sizeof(struct l2tp_eth_net),
};
static const struct l2tp_nl_cmd_ops l2tp_eth_nl_cmd_ops = {
.session_create = l2tp_eth_create,
.session_delete = l2tp_session_delete,
};
static int __init l2tp_eth_init(void)
{
int err = 0;
err = l2tp_nl_register_ops(L2TP_PWTYPE_ETH, &l2tp_eth_nl_cmd_ops);
if (err)
goto out;
err = register_pernet_device(&l2tp_eth_net_ops);
if (err)
goto out_unreg;
pr_info("L2TP ethernet pseudowire support (L2TPv3)\n");
return 0;
out_unreg:
l2tp_nl_unregister_ops(L2TP_PWTYPE_ETH);
out:
return err;
}
static void __exit l2tp_eth_exit(void)
{
unregister_pernet_device(&l2tp_eth_net_ops);
l2tp_nl_unregister_ops(L2TP_PWTYPE_ETH);
}
module_init(l2tp_eth_init);
module_exit(l2tp_eth_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
MODULE_DESCRIPTION("L2TP ethernet pseudowire driver");
MODULE_VERSION("1.0");
MODULE_ALIAS_L2TP_PWTYPE(5);