![Florian Westphal](/assets/img/avatar_default.png)
NF_VERDICT_MASK is currently 0xffff. This is because the upper 16 bits are used to store errno (for NF_DROP) or the queue number (NF_QUEUE verdict). As there are up to 0xffff different queues available, there is no more room to store additional flags. At the moment there are only 6 different verdicts, i.e. we can reduce NF_VERDICT_MASK to 0xff to allow storing additional flags in the 0xff00 space. NF_VERDICT_BITS would then be reduced to 8, but because the value is exported to userspace, this might cause breakage; e.g.: e.g. 'queuenr = (1 << NF_VERDICT_BITS) | NF_QUEUE' would now break. Thus, remove NF_VERDICT_BITS usage in the kernel and move the old value to the 'userspace compat' section. Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Patrick McHardy <kaber@trash.net>
288 lines
6.9 KiB
C
288 lines
6.9 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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*/
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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/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 <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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int nf_register_afinfo(const struct nf_afinfo *afinfo)
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{
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int err;
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err = mutex_lock_interruptible(&afinfo_mutex);
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if (err < 0)
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return err;
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rcu_assign_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_assign_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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struct list_head nf_hooks[NFPROTO_NUMPROTO][NF_MAX_HOOKS] __read_mostly;
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EXPORT_SYMBOL(nf_hooks);
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static DEFINE_MUTEX(nf_hook_mutex);
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int nf_register_hook(struct nf_hook_ops *reg)
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{
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struct nf_hook_ops *elem;
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int err;
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err = mutex_lock_interruptible(&nf_hook_mutex);
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if (err < 0)
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return err;
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list_for_each_entry(elem, &nf_hooks[reg->pf][reg->hooknum], list) {
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if (reg->priority < elem->priority)
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break;
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}
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list_add_rcu(®->list, elem->list.prev);
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mutex_unlock(&nf_hook_mutex);
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return 0;
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}
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EXPORT_SYMBOL(nf_register_hook);
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void nf_unregister_hook(struct nf_hook_ops *reg)
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{
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mutex_lock(&nf_hook_mutex);
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list_del_rcu(®->list);
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mutex_unlock(&nf_hook_mutex);
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synchronize_net();
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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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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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unsigned int nf_iterate(struct list_head *head,
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struct sk_buff *skb,
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unsigned int hook,
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const struct net_device *indev,
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const struct net_device *outdev,
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struct list_head **i,
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int (*okfn)(struct sk_buff *),
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int hook_thresh)
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{
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unsigned int verdict;
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/*
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* The caller must not block between calls to this
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* function because of risk of continuing from deleted element.
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*/
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list_for_each_continue_rcu(*i, head) {
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struct nf_hook_ops *elem = (struct nf_hook_ops *)*i;
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if (hook_thresh > elem->priority)
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continue;
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/* Optimization: we don't need to hold module
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reference here, since function can't sleep. --RR */
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verdict = elem->hook(hook, skb, indev, outdev, okfn);
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if (verdict != NF_ACCEPT) {
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#ifdef CONFIG_NETFILTER_DEBUG
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if (unlikely((verdict & NF_VERDICT_MASK)
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> NF_MAX_VERDICT)) {
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NFDEBUG("Evil return from %p(%u).\n",
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elem->hook, hook);
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continue;
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}
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#endif
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if (verdict != NF_REPEAT)
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return verdict;
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*i = (*i)->prev;
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}
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}
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return NF_ACCEPT;
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}
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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. */
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int nf_hook_slow(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
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struct net_device *indev,
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struct net_device *outdev,
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int (*okfn)(struct sk_buff *),
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int hook_thresh)
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{
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struct list_head *elem;
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unsigned int verdict;
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int ret = 0;
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/* We may already have this, but read-locks nest anyway */
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rcu_read_lock();
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elem = &nf_hooks[pf][hook];
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next_hook:
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verdict = nf_iterate(&nf_hooks[pf][hook], skb, hook, indev,
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outdev, &elem, okfn, hook_thresh);
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if (verdict == NF_ACCEPT || verdict == NF_STOP) {
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ret = 1;
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} else if ((verdict & NF_VERDICT_MASK) == 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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} else if ((verdict & NF_VERDICT_MASK) == NF_QUEUE) {
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ret = nf_queue(skb, elem, pf, hook, indev, outdev, okfn,
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verdict >> NF_VERDICT_QBITS);
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if (ret < 0) {
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if (ret == -ECANCELED)
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goto next_hook;
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kfree_skb(skb);
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}
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ret = 0;
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}
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rcu_read_unlock();
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return ret;
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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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#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
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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 *, struct sk_buff *) __rcu __read_mostly;
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EXPORT_SYMBOL(ip_ct_attach);
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void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb)
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{
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void (*attach)(struct sk_buff *, 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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#endif /* CONFIG_NF_CONNTRACK */
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#ifdef CONFIG_PROC_FS
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struct proc_dir_entry *proc_net_netfilter;
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EXPORT_SYMBOL(proc_net_netfilter);
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#endif
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void __init netfilter_init(void)
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{
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int i, h;
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for (i = 0; i < ARRAY_SIZE(nf_hooks); i++) {
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for (h = 0; h < NF_MAX_HOOKS; h++)
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INIT_LIST_HEAD(&nf_hooks[i][h]);
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}
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#ifdef CONFIG_PROC_FS
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proc_net_netfilter = proc_mkdir("netfilter", init_net.proc_net);
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if (!proc_net_netfilter)
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panic("cannot create netfilter proc entry");
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#endif
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if (netfilter_queue_init() < 0)
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panic("cannot initialize nf_queue");
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if (netfilter_log_init() < 0)
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panic("cannot initialize nf_log");
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}
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#ifdef CONFIG_SYSCTL
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struct ctl_path nf_net_netfilter_sysctl_path[] = {
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{ .procname = "net", },
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{ .procname = "netfilter", },
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{ }
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};
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EXPORT_SYMBOL_GPL(nf_net_netfilter_sysctl_path);
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#endif /* CONFIG_SYSCTL */
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