Revision dc280d93623927570da279e99393879dbbab39e7 authored by Thomas Gleixner on 21 December 2016, 19:19:49 UTC, committed by Thomas Gleixner on 25 December 2016, 09:47:42 UTC
Developers manage to overwrite states blindly without thought. That's fatal and hard to debug. Add sanity checks to make it fail. This requries to restructure the code so that the dynamic state allocation happens in the same lock protected section as the actual store. Otherwise the previous assignment of 'Reserved' to the name field would trigger the overwrite check. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sebastian Siewior <bigeasy@linutronix.de> Link: http://lkml.kernel.org/r/20161221192111.675234535@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
1 parent 59fefd0
nlmon.c
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/netdevice.h>
#include <linux/netlink.h>
#include <net/net_namespace.h>
#include <linux/if_arp.h>
#include <net/rtnetlink.h>
struct pcpu_lstats {
u64 packets;
u64 bytes;
struct u64_stats_sync syncp;
};
static netdev_tx_t nlmon_xmit(struct sk_buff *skb, struct net_device *dev)
{
int len = skb->len;
struct pcpu_lstats *stats = this_cpu_ptr(dev->lstats);
u64_stats_update_begin(&stats->syncp);
stats->bytes += len;
stats->packets++;
u64_stats_update_end(&stats->syncp);
dev_kfree_skb(skb);
return NETDEV_TX_OK;
}
static int nlmon_dev_init(struct net_device *dev)
{
dev->lstats = netdev_alloc_pcpu_stats(struct pcpu_lstats);
return dev->lstats == NULL ? -ENOMEM : 0;
}
static void nlmon_dev_uninit(struct net_device *dev)
{
free_percpu(dev->lstats);
}
struct nlmon {
struct netlink_tap nt;
};
static int nlmon_open(struct net_device *dev)
{
struct nlmon *nlmon = netdev_priv(dev);
nlmon->nt.dev = dev;
nlmon->nt.module = THIS_MODULE;
return netlink_add_tap(&nlmon->nt);
}
static int nlmon_close(struct net_device *dev)
{
struct nlmon *nlmon = netdev_priv(dev);
return netlink_remove_tap(&nlmon->nt);
}
static struct rtnl_link_stats64 *
nlmon_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
{
int i;
u64 bytes = 0, packets = 0;
for_each_possible_cpu(i) {
const struct pcpu_lstats *nl_stats;
u64 tbytes, tpackets;
unsigned int start;
nl_stats = per_cpu_ptr(dev->lstats, i);
do {
start = u64_stats_fetch_begin_irq(&nl_stats->syncp);
tbytes = nl_stats->bytes;
tpackets = nl_stats->packets;
} while (u64_stats_fetch_retry_irq(&nl_stats->syncp, start));
packets += tpackets;
bytes += tbytes;
}
stats->rx_packets = packets;
stats->tx_packets = 0;
stats->rx_bytes = bytes;
stats->tx_bytes = 0;
return stats;
}
static u32 always_on(struct net_device *dev)
{
return 1;
}
static const struct ethtool_ops nlmon_ethtool_ops = {
.get_link = always_on,
};
static const struct net_device_ops nlmon_ops = {
.ndo_init = nlmon_dev_init,
.ndo_uninit = nlmon_dev_uninit,
.ndo_open = nlmon_open,
.ndo_stop = nlmon_close,
.ndo_start_xmit = nlmon_xmit,
.ndo_get_stats64 = nlmon_get_stats64,
};
static void nlmon_setup(struct net_device *dev)
{
dev->type = ARPHRD_NETLINK;
dev->priv_flags |= IFF_NO_QUEUE;
dev->netdev_ops = &nlmon_ops;
dev->ethtool_ops = &nlmon_ethtool_ops;
dev->destructor = free_netdev;
dev->features = NETIF_F_SG | NETIF_F_FRAGLIST |
NETIF_F_HIGHDMA | NETIF_F_LLTX;
dev->flags = IFF_NOARP;
/* That's rather a softlimit here, which, of course,
* can be altered. Not a real MTU, but what is to be
* expected in most cases.
*/
dev->mtu = NLMSG_GOODSIZE;
dev->min_mtu = sizeof(struct nlmsghdr);
}
static int nlmon_validate(struct nlattr *tb[], struct nlattr *data[])
{
if (tb[IFLA_ADDRESS])
return -EINVAL;
return 0;
}
static struct rtnl_link_ops nlmon_link_ops __read_mostly = {
.kind = "nlmon",
.priv_size = sizeof(struct nlmon),
.setup = nlmon_setup,
.validate = nlmon_validate,
};
static __init int nlmon_register(void)
{
return rtnl_link_register(&nlmon_link_ops);
}
static __exit void nlmon_unregister(void)
{
rtnl_link_unregister(&nlmon_link_ops);
}
module_init(nlmon_register);
module_exit(nlmon_unregister);
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>");
MODULE_AUTHOR("Mathieu Geli <geli@enseirb.fr>");
MODULE_DESCRIPTION("Netlink monitoring device");
MODULE_ALIAS_RTNL_LINK("nlmon");
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