| /* 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> |
| #include <net/netfilter/nf_conntrack_extend.h> |
| |
| static struct hlist_head *nf_ct_helper_hash __read_mostly; |
| static unsigned int nf_ct_helper_hsize __read_mostly; |
| static unsigned int nf_ct_helper_count __read_mostly; |
| static int nf_ct_helper_vmalloc; |
| |
| |
| /* Stupid hash, but collision free for the default registrations of the |
| * helpers currently in the kernel. */ |
| static unsigned int helper_hash(const struct nf_conntrack_tuple *tuple) |
| { |
| return (((tuple->src.l3num << 8) | tuple->dst.protonum) ^ |
| tuple->src.u.all) % nf_ct_helper_hsize; |
| } |
| |
| struct nf_conntrack_helper * |
| __nf_ct_helper_find(const struct nf_conntrack_tuple *tuple) |
| { |
| struct nf_conntrack_helper *helper; |
| struct nf_conntrack_tuple_mask mask = { .src.u.all = htons(0xFFFF) }; |
| struct hlist_node *n; |
| unsigned int h; |
| |
| if (!nf_ct_helper_count) |
| return NULL; |
| |
| h = helper_hash(tuple); |
| hlist_for_each_entry(helper, n, &nf_ct_helper_hash[h], hnode) { |
| if (nf_ct_tuple_src_mask_cmp(tuple, &helper->tuple, &mask)) |
| return helper; |
| } |
| 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; |
| struct hlist_node *n; |
| unsigned int i; |
| |
| for (i = 0; i < nf_ct_helper_hsize; i++) { |
| hlist_for_each_entry(h, n, &nf_ct_helper_hash[i], hnode) { |
| if (!strcmp(h->name, name)) |
| return h; |
| } |
| } |
| return NULL; |
| } |
| EXPORT_SYMBOL_GPL(__nf_conntrack_helper_find_byname); |
| |
| struct nf_conn_help *nf_ct_helper_ext_add(struct nf_conn *ct, gfp_t gfp) |
| { |
| struct nf_conn_help *help; |
| |
| help = nf_ct_ext_add(ct, NF_CT_EXT_HELPER, gfp); |
| if (help) |
| INIT_HLIST_HEAD(&help->expectations); |
| else |
| pr_debug("failed to add helper extension area"); |
| return help; |
| } |
| EXPORT_SYMBOL_GPL(nf_ct_helper_ext_add); |
| |
| 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); |
| rcu_assign_pointer(help->helper, NULL); |
| } |
| return 0; |
| } |
| |
| int nf_conntrack_helper_register(struct nf_conntrack_helper *me) |
| { |
| unsigned int h = helper_hash(&me->tuple); |
| |
| BUG_ON(me->timeout == 0); |
| |
| write_lock_bh(&nf_conntrack_lock); |
| hlist_add_head(&me->hnode, &nf_ct_helper_hash[h]); |
| nf_ct_helper_count++; |
| 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) |
| { |
| struct nf_conntrack_tuple_hash *h; |
| struct nf_conntrack_expect *exp; |
| struct hlist_node *n, *next; |
| unsigned int i; |
| |
| /* Need write lock here, to delete helper. */ |
| write_lock_bh(&nf_conntrack_lock); |
| hlist_del(&me->hnode); |
| nf_ct_helper_count--; |
| |
| /* Get rid of expectations */ |
| for (i = 0; i < nf_ct_expect_hsize; i++) { |
| hlist_for_each_entry_safe(exp, n, next, |
| &nf_ct_expect_hash[i], hnode) { |
| 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_ct_expect_put(exp); |
| } |
| } |
| } |
| |
| /* Get rid of expecteds, set helpers to NULL. */ |
| hlist_for_each_entry(h, n, &unconfirmed, hnode) |
| unhelp(h, me); |
| for (i = 0; i < nf_conntrack_htable_size; i++) { |
| hlist_for_each_entry(h, n, &nf_conntrack_hash[i], hnode) |
| 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); |
| |
| static struct nf_ct_ext_type helper_extend __read_mostly = { |
| .len = sizeof(struct nf_conn_help), |
| .align = __alignof__(struct nf_conn_help), |
| .id = NF_CT_EXT_HELPER, |
| }; |
| |
| int nf_conntrack_helper_init() |
| { |
| int err; |
| |
| nf_ct_helper_hsize = 1; /* gets rounded up to use one page */ |
| nf_ct_helper_hash = nf_ct_alloc_hashtable(&nf_ct_helper_hsize, |
| &nf_ct_helper_vmalloc); |
| if (!nf_ct_helper_hash) |
| return -ENOMEM; |
| |
| err = nf_ct_extend_register(&helper_extend); |
| if (err < 0) |
| goto err1; |
| |
| return 0; |
| |
| err1: |
| nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_vmalloc, |
| nf_ct_helper_hsize); |
| return err; |
| } |
| |
| void nf_conntrack_helper_fini() |
| { |
| nf_ct_extend_unregister(&helper_extend); |
| nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_vmalloc, |
| nf_ct_helper_hsize); |
| } |