148 lines
3.8 KiB
C
148 lines
3.8 KiB
C
/* Helper handling for netfilter. */
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/* (C) 1999-2001 Paul `Rusty' Russell
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* (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
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* (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/types.h>
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#include <linux/netfilter.h>
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#include <linux/module.h>
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#include <linux/skbuff.h>
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#include <linux/vmalloc.h>
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#include <linux/stddef.h>
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#include <linux/slab.h>
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#include <linux/random.h>
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#include <linux/err.h>
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#include <linux/kernel.h>
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#include <linux/netdevice.h>
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#include <net/netfilter/nf_conntrack.h>
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#include <net/netfilter/nf_conntrack_l3proto.h>
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#include <net/netfilter/nf_conntrack_l4proto.h>
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#include <net/netfilter/nf_conntrack_helper.h>
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#include <net/netfilter/nf_conntrack_core.h>
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static __read_mostly LIST_HEAD(helpers);
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struct nf_conntrack_helper *
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__nf_ct_helper_find(const struct nf_conntrack_tuple *tuple)
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{
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struct nf_conntrack_helper *h;
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list_for_each_entry(h, &helpers, list) {
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if (nf_ct_tuple_mask_cmp(tuple, &h->tuple, &h->mask))
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return h;
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}
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return NULL;
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}
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struct nf_conntrack_helper *
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nf_ct_helper_find_get( const struct nf_conntrack_tuple *tuple)
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{
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struct nf_conntrack_helper *helper;
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/* need nf_conntrack_lock to assure that helper exists until
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* try_module_get() is called */
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read_lock_bh(&nf_conntrack_lock);
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helper = __nf_ct_helper_find(tuple);
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if (helper) {
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/* need to increase module usage count to assure helper will
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* not go away while the caller is e.g. busy putting a
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* conntrack in the hash that uses the helper */
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if (!try_module_get(helper->me))
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helper = NULL;
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}
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read_unlock_bh(&nf_conntrack_lock);
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return helper;
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}
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void nf_ct_helper_put(struct nf_conntrack_helper *helper)
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{
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module_put(helper->me);
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}
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struct nf_conntrack_helper *
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__nf_conntrack_helper_find_byname(const char *name)
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{
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struct nf_conntrack_helper *h;
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list_for_each_entry(h, &helpers, list) {
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if (!strcmp(h->name, name))
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return h;
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}
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return NULL;
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}
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static inline int unhelp(struct nf_conntrack_tuple_hash *i,
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const struct nf_conntrack_helper *me)
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{
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struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(i);
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struct nf_conn_help *help = nfct_help(ct);
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if (help && help->helper == me) {
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nf_conntrack_event(IPCT_HELPER, ct);
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help->helper = NULL;
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}
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return 0;
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}
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int nf_conntrack_helper_register(struct nf_conntrack_helper *me)
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{
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int ret;
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BUG_ON(me->timeout == 0);
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ret = nf_conntrack_register_cache(NF_CT_F_HELP, "nf_conntrack:help",
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sizeof(struct nf_conn)
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+ sizeof(struct nf_conn_help)
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+ __alignof__(struct nf_conn_help));
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if (ret < 0) {
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printk(KERN_ERR "nf_conntrack_helper_register: Unable to create slab cache for conntracks\n");
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return ret;
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}
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write_lock_bh(&nf_conntrack_lock);
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list_add(&me->list, &helpers);
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write_unlock_bh(&nf_conntrack_lock);
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return 0;
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}
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void nf_conntrack_helper_unregister(struct nf_conntrack_helper *me)
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{
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unsigned int i;
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struct nf_conntrack_tuple_hash *h;
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struct nf_conntrack_expect *exp, *tmp;
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/* Need write lock here, to delete helper. */
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write_lock_bh(&nf_conntrack_lock);
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list_del(&me->list);
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/* Get rid of expectations */
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list_for_each_entry_safe(exp, tmp, &nf_conntrack_expect_list, list) {
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struct nf_conn_help *help = nfct_help(exp->master);
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if (help->helper == me && del_timer(&exp->timeout)) {
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nf_ct_unlink_expect(exp);
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nf_conntrack_expect_put(exp);
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}
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}
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/* Get rid of expecteds, set helpers to NULL. */
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list_for_each_entry(h, &unconfirmed, list)
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unhelp(h, me);
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for (i = 0; i < nf_conntrack_htable_size; i++) {
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list_for_each_entry(h, &nf_conntrack_hash[i], list)
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unhelp(h, me);
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}
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write_unlock_bh(&nf_conntrack_lock);
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/* Someone could be still looking at the helper in a bh. */
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synchronize_net();
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}
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