3b233fe043
This patch fixes the following warning introduced in e4fc408e0e
("packet: nlmon: virtual netlink monitoring device for packet
sockets") reported by Dan Carpenter:
warning: "drivers/net/nlmon.c:31 nlmon_is_valid_mtu()
warn: always true condition '(new_mtu <= ((~0 >> 1))) =>
(s32min-s32max <= s32max)'"
Thus, we should simply remove the test against INT_MAX. Next to that
we also need to explicitly cast the sizeof() case as the comparison
is type promoted to unsigned long so negative values are then
valid instead of invalid. While at it, this also adds a comment about
Netlink and MTUs.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
174 lines
3.6 KiB
C
174 lines
3.6 KiB
C
#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/netdevice.h>
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#include <linux/netlink.h>
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#include <net/net_namespace.h>
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#include <linux/if_arp.h>
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struct pcpu_lstats {
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u64 packets;
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u64 bytes;
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struct u64_stats_sync syncp;
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};
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static netdev_tx_t nlmon_xmit(struct sk_buff *skb, struct net_device *dev)
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{
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int len = skb->len;
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struct pcpu_lstats *stats = this_cpu_ptr(dev->lstats);
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u64_stats_update_begin(&stats->syncp);
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stats->bytes += len;
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stats->packets++;
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u64_stats_update_end(&stats->syncp);
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dev_kfree_skb(skb);
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return NETDEV_TX_OK;
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}
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static int nlmon_is_valid_mtu(int new_mtu)
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{
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/* Note that in netlink we do not really have an upper limit. On
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* default, we use NLMSG_GOODSIZE. Here at least we should make
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* sure that it's at least the header size.
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*/
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return new_mtu >= (int) sizeof(struct nlmsghdr);
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}
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static int nlmon_change_mtu(struct net_device *dev, int new_mtu)
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{
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if (!nlmon_is_valid_mtu(new_mtu))
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return -EINVAL;
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dev->mtu = new_mtu;
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return 0;
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}
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static int nlmon_dev_init(struct net_device *dev)
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{
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dev->lstats = alloc_percpu(struct pcpu_lstats);
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return dev->lstats == NULL ? -ENOMEM : 0;
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}
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static void nlmon_dev_uninit(struct net_device *dev)
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{
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free_percpu(dev->lstats);
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}
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static struct netlink_tap nlmon_tap;
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static int nlmon_open(struct net_device *dev)
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{
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return netlink_add_tap(&nlmon_tap);
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}
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static int nlmon_close(struct net_device *dev)
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{
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return netlink_remove_tap(&nlmon_tap);
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}
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static struct rtnl_link_stats64 *
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nlmon_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
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{
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int i;
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u64 bytes = 0, packets = 0;
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for_each_possible_cpu(i) {
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const struct pcpu_lstats *nl_stats;
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u64 tbytes, tpackets;
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unsigned int start;
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nl_stats = per_cpu_ptr(dev->lstats, i);
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do {
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start = u64_stats_fetch_begin_bh(&nl_stats->syncp);
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tbytes = nl_stats->bytes;
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tpackets = nl_stats->packets;
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} while (u64_stats_fetch_retry_bh(&nl_stats->syncp, start));
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packets += tpackets;
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bytes += tbytes;
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}
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stats->rx_packets = packets;
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stats->tx_packets = 0;
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stats->rx_bytes = bytes;
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stats->tx_bytes = 0;
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return stats;
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}
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static u32 always_on(struct net_device *dev)
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{
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return 1;
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}
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static const struct ethtool_ops nlmon_ethtool_ops = {
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.get_link = always_on,
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};
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static const struct net_device_ops nlmon_ops = {
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.ndo_init = nlmon_dev_init,
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.ndo_uninit = nlmon_dev_uninit,
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.ndo_open = nlmon_open,
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.ndo_stop = nlmon_close,
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.ndo_start_xmit = nlmon_xmit,
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.ndo_get_stats64 = nlmon_get_stats64,
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.ndo_change_mtu = nlmon_change_mtu,
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};
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static struct netlink_tap nlmon_tap __read_mostly = {
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.module = THIS_MODULE,
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};
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static void nlmon_setup(struct net_device *dev)
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{
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dev->type = ARPHRD_NETLINK;
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dev->tx_queue_len = 0;
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dev->netdev_ops = &nlmon_ops;
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dev->ethtool_ops = &nlmon_ethtool_ops;
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dev->destructor = free_netdev;
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dev->features = NETIF_F_FRAGLIST | NETIF_F_HIGHDMA;
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dev->flags = IFF_NOARP;
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/* That's rather a softlimit here, which, of course,
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* can be altered. Not a real MTU, but what is to be
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* expected in most cases.
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*/
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dev->mtu = NLMSG_GOODSIZE;
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}
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static __init int nlmon_register(void)
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{
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int err;
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struct net_device *nldev;
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nldev = nlmon_tap.dev = alloc_netdev(0, "netlink", nlmon_setup);
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if (unlikely(nldev == NULL))
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return -ENOMEM;
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err = register_netdev(nldev);
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if (unlikely(err))
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free_netdev(nldev);
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return err;
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}
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static __exit void nlmon_unregister(void)
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{
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struct net_device *nldev = nlmon_tap.dev;
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unregister_netdev(nldev);
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}
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module_init(nlmon_register);
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module_exit(nlmon_unregister);
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MODULE_LICENSE("GPL v2");
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MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>");
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MODULE_AUTHOR("Mathieu Geli <geli@enseirb.fr>");
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MODULE_DESCRIPTION("Netlink monitoring device");
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