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![Aaron Conole](/assets/img/avatar_default.png)
This is to facilitate converting from a singly-linked list to an array of elements. Signed-off-by: Aaron Conole <aconole@bytheb.org> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
501 lines
11 KiB
C
501 lines
11 KiB
C
/* netfilter.c: look after the filters for various protocols.
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* Heavily influenced by the old firewall.c by David Bonn and Alan Cox.
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*
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* Thanks to Rob `CmdrTaco' Malda for not influencing this code in any
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* way.
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*
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* Rusty Russell (C)2000 -- This code is GPL.
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* Patrick McHardy (c) 2006-2012
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*/
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#include <linux/kernel.h>
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#include <linux/netfilter.h>
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#include <net/protocol.h>
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#include <linux/init.h>
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#include <linux/skbuff.h>
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#include <linux/wait.h>
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#include <linux/module.h>
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#include <linux/interrupt.h>
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#include <linux/if.h>
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#include <linux/netdevice.h>
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#include <linux/netfilter_ipv6.h>
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#include <linux/inetdevice.h>
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#include <linux/proc_fs.h>
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#include <linux/mutex.h>
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#include <linux/slab.h>
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#include <linux/rcupdate.h>
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#include <net/net_namespace.h>
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#include <net/sock.h>
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#include "nf_internals.h"
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static DEFINE_MUTEX(afinfo_mutex);
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const struct nf_afinfo __rcu *nf_afinfo[NFPROTO_NUMPROTO] __read_mostly;
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EXPORT_SYMBOL(nf_afinfo);
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const struct nf_ipv6_ops __rcu *nf_ipv6_ops __read_mostly;
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EXPORT_SYMBOL_GPL(nf_ipv6_ops);
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DEFINE_PER_CPU(bool, nf_skb_duplicated);
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EXPORT_SYMBOL_GPL(nf_skb_duplicated);
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int nf_register_afinfo(const struct nf_afinfo *afinfo)
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{
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mutex_lock(&afinfo_mutex);
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RCU_INIT_POINTER(nf_afinfo[afinfo->family], afinfo);
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mutex_unlock(&afinfo_mutex);
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return 0;
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}
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EXPORT_SYMBOL_GPL(nf_register_afinfo);
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void nf_unregister_afinfo(const struct nf_afinfo *afinfo)
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{
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mutex_lock(&afinfo_mutex);
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RCU_INIT_POINTER(nf_afinfo[afinfo->family], NULL);
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mutex_unlock(&afinfo_mutex);
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synchronize_rcu();
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}
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EXPORT_SYMBOL_GPL(nf_unregister_afinfo);
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#ifdef HAVE_JUMP_LABEL
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struct static_key nf_hooks_needed[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
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EXPORT_SYMBOL(nf_hooks_needed);
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#endif
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static DEFINE_MUTEX(nf_hook_mutex);
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#define nf_entry_dereference(e) \
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rcu_dereference_protected(e, lockdep_is_held(&nf_hook_mutex))
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static struct nf_hook_entry __rcu **nf_hook_entry_head(struct net *net, const struct nf_hook_ops *reg)
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{
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if (reg->pf != NFPROTO_NETDEV)
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return net->nf.hooks[reg->pf]+reg->hooknum;
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#ifdef CONFIG_NETFILTER_INGRESS
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if (reg->hooknum == NF_NETDEV_INGRESS) {
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if (reg->dev && dev_net(reg->dev) == net)
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return ®->dev->nf_hooks_ingress;
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}
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#endif
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return NULL;
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}
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int nf_register_net_hook(struct net *net, const struct nf_hook_ops *reg)
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{
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struct nf_hook_entry __rcu **pp;
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struct nf_hook_entry *entry, *p;
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if (reg->pf == NFPROTO_NETDEV) {
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#ifndef CONFIG_NETFILTER_INGRESS
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if (reg->hooknum == NF_NETDEV_INGRESS)
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return -EOPNOTSUPP;
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#endif
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if (reg->hooknum != NF_NETDEV_INGRESS ||
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!reg->dev || dev_net(reg->dev) != net)
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return -EINVAL;
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}
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pp = nf_hook_entry_head(net, reg);
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if (!pp)
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return -EINVAL;
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entry = kmalloc(sizeof(*entry), GFP_KERNEL);
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if (!entry)
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return -ENOMEM;
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nf_hook_entry_init(entry, reg);
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mutex_lock(&nf_hook_mutex);
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/* Find the spot in the list */
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for (; (p = nf_entry_dereference(*pp)) != NULL; pp = &p->next) {
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if (reg->priority < nf_hook_entry_priority(p))
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break;
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}
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rcu_assign_pointer(entry->next, p);
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rcu_assign_pointer(*pp, entry);
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mutex_unlock(&nf_hook_mutex);
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#ifdef CONFIG_NETFILTER_INGRESS
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if (reg->pf == NFPROTO_NETDEV && reg->hooknum == NF_NETDEV_INGRESS)
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net_inc_ingress_queue();
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#endif
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#ifdef HAVE_JUMP_LABEL
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static_key_slow_inc(&nf_hooks_needed[reg->pf][reg->hooknum]);
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#endif
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return 0;
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}
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EXPORT_SYMBOL(nf_register_net_hook);
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void nf_unregister_net_hook(struct net *net, const struct nf_hook_ops *reg)
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{
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struct nf_hook_entry __rcu **pp;
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struct nf_hook_entry *p;
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pp = nf_hook_entry_head(net, reg);
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if (WARN_ON_ONCE(!pp))
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return;
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mutex_lock(&nf_hook_mutex);
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for (; (p = nf_entry_dereference(*pp)) != NULL; pp = &p->next) {
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if (nf_hook_entry_ops(p) == reg) {
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rcu_assign_pointer(*pp, p->next);
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break;
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}
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}
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mutex_unlock(&nf_hook_mutex);
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if (!p) {
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WARN(1, "nf_unregister_net_hook: hook not found!\n");
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return;
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}
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#ifdef CONFIG_NETFILTER_INGRESS
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if (reg->pf == NFPROTO_NETDEV && reg->hooknum == NF_NETDEV_INGRESS)
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net_dec_ingress_queue();
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#endif
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#ifdef HAVE_JUMP_LABEL
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static_key_slow_dec(&nf_hooks_needed[reg->pf][reg->hooknum]);
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#endif
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synchronize_net();
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nf_queue_nf_hook_drop(net, p);
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/* other cpu might still process nfqueue verdict that used reg */
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synchronize_net();
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kfree(p);
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}
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EXPORT_SYMBOL(nf_unregister_net_hook);
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int nf_register_net_hooks(struct net *net, const struct nf_hook_ops *reg,
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unsigned int n)
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{
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unsigned int i;
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int err = 0;
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for (i = 0; i < n; i++) {
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err = nf_register_net_hook(net, ®[i]);
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if (err)
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goto err;
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}
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return err;
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err:
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if (i > 0)
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nf_unregister_net_hooks(net, reg, i);
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return err;
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}
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EXPORT_SYMBOL(nf_register_net_hooks);
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void nf_unregister_net_hooks(struct net *net, const struct nf_hook_ops *reg,
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unsigned int n)
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{
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while (n-- > 0)
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nf_unregister_net_hook(net, ®[n]);
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}
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EXPORT_SYMBOL(nf_unregister_net_hooks);
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static LIST_HEAD(nf_hook_list);
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static int _nf_register_hook(struct nf_hook_ops *reg)
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{
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struct net *net, *last;
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int ret;
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for_each_net(net) {
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ret = nf_register_net_hook(net, reg);
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if (ret && ret != -ENOENT)
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goto rollback;
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}
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list_add_tail(®->list, &nf_hook_list);
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return 0;
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rollback:
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last = net;
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for_each_net(net) {
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if (net == last)
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break;
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nf_unregister_net_hook(net, reg);
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}
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return ret;
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}
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int nf_register_hook(struct nf_hook_ops *reg)
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{
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int ret;
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rtnl_lock();
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ret = _nf_register_hook(reg);
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rtnl_unlock();
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return ret;
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}
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EXPORT_SYMBOL(nf_register_hook);
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static void _nf_unregister_hook(struct nf_hook_ops *reg)
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{
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struct net *net;
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list_del(®->list);
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for_each_net(net)
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nf_unregister_net_hook(net, reg);
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}
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void nf_unregister_hook(struct nf_hook_ops *reg)
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{
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rtnl_lock();
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_nf_unregister_hook(reg);
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rtnl_unlock();
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}
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EXPORT_SYMBOL(nf_unregister_hook);
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int nf_register_hooks(struct nf_hook_ops *reg, unsigned int n)
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{
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unsigned int i;
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int err = 0;
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for (i = 0; i < n; i++) {
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err = nf_register_hook(®[i]);
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if (err)
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goto err;
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}
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return err;
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err:
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if (i > 0)
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nf_unregister_hooks(reg, i);
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return err;
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}
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EXPORT_SYMBOL(nf_register_hooks);
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/* Caller MUST take rtnl_lock() */
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int _nf_register_hooks(struct nf_hook_ops *reg, unsigned int n)
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{
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unsigned int i;
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int err = 0;
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for (i = 0; i < n; i++) {
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err = _nf_register_hook(®[i]);
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if (err)
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goto err;
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}
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return err;
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err:
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if (i > 0)
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_nf_unregister_hooks(reg, i);
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return err;
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}
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EXPORT_SYMBOL(_nf_register_hooks);
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void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n)
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{
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while (n-- > 0)
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nf_unregister_hook(®[n]);
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}
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EXPORT_SYMBOL(nf_unregister_hooks);
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/* Caller MUST take rtnl_lock */
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void _nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n)
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{
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while (n-- > 0)
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_nf_unregister_hook(®[n]);
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}
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EXPORT_SYMBOL(_nf_unregister_hooks);
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/* Returns 1 if okfn() needs to be executed by the caller,
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* -EPERM for NF_DROP, 0 otherwise. Caller must hold rcu_read_lock. */
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int nf_hook_slow(struct sk_buff *skb, struct nf_hook_state *state,
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struct nf_hook_entry *entry)
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{
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unsigned int verdict;
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int ret;
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do {
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verdict = nf_hook_entry_hookfn(entry, skb, state);
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switch (verdict & NF_VERDICT_MASK) {
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case NF_ACCEPT:
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entry = rcu_dereference(entry->next);
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break;
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case NF_DROP:
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kfree_skb(skb);
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ret = NF_DROP_GETERR(verdict);
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if (ret == 0)
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ret = -EPERM;
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return ret;
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case NF_QUEUE:
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ret = nf_queue(skb, state, &entry, verdict);
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if (ret == 1 && entry)
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continue;
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return ret;
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default:
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/* Implicit handling for NF_STOLEN, as well as any other
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* non conventional verdicts.
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*/
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return 0;
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}
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} while (entry);
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return 1;
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}
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EXPORT_SYMBOL(nf_hook_slow);
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int skb_make_writable(struct sk_buff *skb, unsigned int writable_len)
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{
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if (writable_len > skb->len)
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return 0;
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/* Not exclusive use of packet? Must copy. */
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if (!skb_cloned(skb)) {
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if (writable_len <= skb_headlen(skb))
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return 1;
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} else if (skb_clone_writable(skb, writable_len))
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return 1;
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if (writable_len <= skb_headlen(skb))
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writable_len = 0;
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else
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writable_len -= skb_headlen(skb);
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return !!__pskb_pull_tail(skb, writable_len);
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}
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EXPORT_SYMBOL(skb_make_writable);
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/* This needs to be compiled in any case to avoid dependencies between the
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* nfnetlink_queue code and nf_conntrack.
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*/
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struct nfnl_ct_hook __rcu *nfnl_ct_hook __read_mostly;
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EXPORT_SYMBOL_GPL(nfnl_ct_hook);
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#if IS_ENABLED(CONFIG_NF_CONNTRACK)
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/* This does not belong here, but locally generated errors need it if connection
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tracking in use: without this, connection may not be in hash table, and hence
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manufactured ICMP or RST packets will not be associated with it. */
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void (*ip_ct_attach)(struct sk_buff *, const struct sk_buff *)
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__rcu __read_mostly;
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EXPORT_SYMBOL(ip_ct_attach);
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void nf_ct_attach(struct sk_buff *new, const struct sk_buff *skb)
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{
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void (*attach)(struct sk_buff *, const struct sk_buff *);
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if (skb->nfct) {
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rcu_read_lock();
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attach = rcu_dereference(ip_ct_attach);
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if (attach)
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attach(new, skb);
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rcu_read_unlock();
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}
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}
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EXPORT_SYMBOL(nf_ct_attach);
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void (*nf_ct_destroy)(struct nf_conntrack *) __rcu __read_mostly;
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EXPORT_SYMBOL(nf_ct_destroy);
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void nf_conntrack_destroy(struct nf_conntrack *nfct)
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{
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void (*destroy)(struct nf_conntrack *);
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rcu_read_lock();
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destroy = rcu_dereference(nf_ct_destroy);
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BUG_ON(destroy == NULL);
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destroy(nfct);
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rcu_read_unlock();
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}
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EXPORT_SYMBOL(nf_conntrack_destroy);
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/* Built-in default zone used e.g. by modules. */
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const struct nf_conntrack_zone nf_ct_zone_dflt = {
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.id = NF_CT_DEFAULT_ZONE_ID,
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.dir = NF_CT_DEFAULT_ZONE_DIR,
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};
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EXPORT_SYMBOL_GPL(nf_ct_zone_dflt);
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#endif /* CONFIG_NF_CONNTRACK */
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#ifdef CONFIG_NF_NAT_NEEDED
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void (*nf_nat_decode_session_hook)(struct sk_buff *, struct flowi *);
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EXPORT_SYMBOL(nf_nat_decode_session_hook);
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#endif
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static int nf_register_hook_list(struct net *net)
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{
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struct nf_hook_ops *elem;
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int ret;
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rtnl_lock();
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list_for_each_entry(elem, &nf_hook_list, list) {
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ret = nf_register_net_hook(net, elem);
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if (ret && ret != -ENOENT)
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goto out_undo;
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}
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rtnl_unlock();
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return 0;
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out_undo:
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list_for_each_entry_continue_reverse(elem, &nf_hook_list, list)
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nf_unregister_net_hook(net, elem);
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rtnl_unlock();
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return ret;
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}
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static void nf_unregister_hook_list(struct net *net)
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{
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struct nf_hook_ops *elem;
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rtnl_lock();
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list_for_each_entry(elem, &nf_hook_list, list)
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nf_unregister_net_hook(net, elem);
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rtnl_unlock();
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}
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static int __net_init netfilter_net_init(struct net *net)
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{
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int i, h, ret;
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for (i = 0; i < ARRAY_SIZE(net->nf.hooks); i++) {
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for (h = 0; h < NF_MAX_HOOKS; h++)
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RCU_INIT_POINTER(net->nf.hooks[i][h], NULL);
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}
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#ifdef CONFIG_PROC_FS
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net->nf.proc_netfilter = proc_net_mkdir(net, "netfilter",
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net->proc_net);
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if (!net->nf.proc_netfilter) {
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if (!net_eq(net, &init_net))
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pr_err("cannot create netfilter proc entry");
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return -ENOMEM;
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}
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#endif
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ret = nf_register_hook_list(net);
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if (ret)
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remove_proc_entry("netfilter", net->proc_net);
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return ret;
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}
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static void __net_exit netfilter_net_exit(struct net *net)
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{
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nf_unregister_hook_list(net);
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remove_proc_entry("netfilter", net->proc_net);
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}
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static struct pernet_operations netfilter_net_ops = {
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.init = netfilter_net_init,
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.exit = netfilter_net_exit,
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};
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int __init netfilter_init(void)
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{
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int ret;
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ret = register_pernet_subsys(&netfilter_net_ops);
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if (ret < 0)
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goto err;
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ret = netfilter_log_init();
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if (ret < 0)
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goto err_pernet;
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return 0;
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err_pernet:
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unregister_pernet_subsys(&netfilter_net_ops);
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err:
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return ret;
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}
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