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