netfilter: netns ct: walk netns list under RTNL
[linux-2.6.git] / net / netfilter / nf_conntrack_helper.c
1 /* Helper handling for netfilter. */
2
3 /* (C) 1999-2001 Paul `Rusty' Russell
4  * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
5  * (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org>
6  *
7  * This program is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License version 2 as
9  * published by the Free Software Foundation.
10  */
11
12 #include <linux/types.h>
13 #include <linux/netfilter.h>
14 #include <linux/module.h>
15 #include <linux/skbuff.h>
16 #include <linux/vmalloc.h>
17 #include <linux/stddef.h>
18 #include <linux/slab.h>
19 #include <linux/random.h>
20 #include <linux/err.h>
21 #include <linux/kernel.h>
22 #include <linux/netdevice.h>
23 #include <linux/rculist.h>
24 #include <linux/rtnetlink.h>
25
26 #include <net/netfilter/nf_conntrack.h>
27 #include <net/netfilter/nf_conntrack_l3proto.h>
28 #include <net/netfilter/nf_conntrack_l4proto.h>
29 #include <net/netfilter/nf_conntrack_helper.h>
30 #include <net/netfilter/nf_conntrack_core.h>
31 #include <net/netfilter/nf_conntrack_extend.h>
32
33 static DEFINE_MUTEX(nf_ct_helper_mutex);
34 static struct hlist_head *nf_ct_helper_hash __read_mostly;
35 static unsigned int nf_ct_helper_hsize __read_mostly;
36 static unsigned int nf_ct_helper_count __read_mostly;
37 static int nf_ct_helper_vmalloc;
38
39
40 /* Stupid hash, but collision free for the default registrations of the
41  * helpers currently in the kernel. */
42 static unsigned int helper_hash(const struct nf_conntrack_tuple *tuple)
43 {
44         return (((tuple->src.l3num << 8) | tuple->dst.protonum) ^
45                 (__force __u16)tuple->src.u.all) % nf_ct_helper_hsize;
46 }
47
48 struct nf_conntrack_helper *
49 __nf_ct_helper_find(const struct nf_conntrack_tuple *tuple)
50 {
51         struct nf_conntrack_helper *helper;
52         struct nf_conntrack_tuple_mask mask = { .src.u.all = htons(0xFFFF) };
53         struct hlist_node *n;
54         unsigned int h;
55
56         if (!nf_ct_helper_count)
57                 return NULL;
58
59         h = helper_hash(tuple);
60         hlist_for_each_entry_rcu(helper, n, &nf_ct_helper_hash[h], hnode) {
61                 if (nf_ct_tuple_src_mask_cmp(tuple, &helper->tuple, &mask))
62                         return helper;
63         }
64         return NULL;
65 }
66 EXPORT_SYMBOL_GPL(__nf_ct_helper_find);
67
68 struct nf_conntrack_helper *
69 __nf_conntrack_helper_find_byname(const char *name)
70 {
71         struct nf_conntrack_helper *h;
72         struct hlist_node *n;
73         unsigned int i;
74
75         for (i = 0; i < nf_ct_helper_hsize; i++) {
76                 hlist_for_each_entry_rcu(h, n, &nf_ct_helper_hash[i], hnode) {
77                         if (!strcmp(h->name, name))
78                                 return h;
79                 }
80         }
81         return NULL;
82 }
83 EXPORT_SYMBOL_GPL(__nf_conntrack_helper_find_byname);
84
85 struct nf_conn_help *nf_ct_helper_ext_add(struct nf_conn *ct, gfp_t gfp)
86 {
87         struct nf_conn_help *help;
88
89         help = nf_ct_ext_add(ct, NF_CT_EXT_HELPER, gfp);
90         if (help)
91                 INIT_HLIST_HEAD(&help->expectations);
92         else
93                 pr_debug("failed to add helper extension area");
94         return help;
95 }
96 EXPORT_SYMBOL_GPL(nf_ct_helper_ext_add);
97
98 static inline int unhelp(struct nf_conntrack_tuple_hash *i,
99                          const struct nf_conntrack_helper *me)
100 {
101         struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(i);
102         struct nf_conn_help *help = nfct_help(ct);
103
104         if (help && help->helper == me) {
105                 nf_conntrack_event(IPCT_HELPER, ct);
106                 rcu_assign_pointer(help->helper, NULL);
107         }
108         return 0;
109 }
110
111 int nf_conntrack_helper_register(struct nf_conntrack_helper *me)
112 {
113         unsigned int h = helper_hash(&me->tuple);
114
115         BUG_ON(me->expect_policy == NULL);
116         BUG_ON(me->expect_class_max >= NF_CT_MAX_EXPECT_CLASSES);
117
118         mutex_lock(&nf_ct_helper_mutex);
119         hlist_add_head_rcu(&me->hnode, &nf_ct_helper_hash[h]);
120         nf_ct_helper_count++;
121         mutex_unlock(&nf_ct_helper_mutex);
122
123         return 0;
124 }
125 EXPORT_SYMBOL_GPL(nf_conntrack_helper_register);
126
127 static void __nf_conntrack_helper_unregister(struct nf_conntrack_helper *me,
128                                              struct net *net)
129 {
130         struct nf_conntrack_tuple_hash *h;
131         struct nf_conntrack_expect *exp;
132         const struct hlist_node *n, *next;
133         unsigned int i;
134
135         /* Get rid of expectations */
136         for (i = 0; i < nf_ct_expect_hsize; i++) {
137                 hlist_for_each_entry_safe(exp, n, next,
138                                           &net->ct.expect_hash[i], hnode) {
139                         struct nf_conn_help *help = nfct_help(exp->master);
140                         if ((help->helper == me || exp->helper == me) &&
141                             del_timer(&exp->timeout)) {
142                                 nf_ct_unlink_expect(exp);
143                                 nf_ct_expect_put(exp);
144                         }
145                 }
146         }
147
148         /* Get rid of expecteds, set helpers to NULL. */
149         hlist_for_each_entry(h, n, &net->ct.unconfirmed, hnode)
150                 unhelp(h, me);
151         for (i = 0; i < nf_conntrack_htable_size; i++) {
152                 hlist_for_each_entry(h, n, &net->ct.hash[i], hnode)
153                         unhelp(h, me);
154         }
155 }
156
157 void nf_conntrack_helper_unregister(struct nf_conntrack_helper *me)
158 {
159         struct net *net;
160
161         mutex_lock(&nf_ct_helper_mutex);
162         hlist_del_rcu(&me->hnode);
163         nf_ct_helper_count--;
164         mutex_unlock(&nf_ct_helper_mutex);
165
166         /* Make sure every nothing is still using the helper unless its a
167          * connection in the hash.
168          */
169         synchronize_rcu();
170
171         rtnl_lock();
172         spin_lock_bh(&nf_conntrack_lock);
173         for_each_net(net)
174                 __nf_conntrack_helper_unregister(me, net);
175         spin_unlock_bh(&nf_conntrack_lock);
176         rtnl_unlock();
177 }
178 EXPORT_SYMBOL_GPL(nf_conntrack_helper_unregister);
179
180 static struct nf_ct_ext_type helper_extend __read_mostly = {
181         .len    = sizeof(struct nf_conn_help),
182         .align  = __alignof__(struct nf_conn_help),
183         .id     = NF_CT_EXT_HELPER,
184 };
185
186 int nf_conntrack_helper_init(void)
187 {
188         int err;
189
190         nf_ct_helper_hsize = 1; /* gets rounded up to use one page */
191         nf_ct_helper_hash = nf_ct_alloc_hashtable(&nf_ct_helper_hsize,
192                                                   &nf_ct_helper_vmalloc);
193         if (!nf_ct_helper_hash)
194                 return -ENOMEM;
195
196         err = nf_ct_extend_register(&helper_extend);
197         if (err < 0)
198                 goto err1;
199
200         return 0;
201
202 err1:
203         nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_vmalloc,
204                              nf_ct_helper_hsize);
205         return err;
206 }
207
208 void nf_conntrack_helper_fini(void)
209 {
210         nf_ct_extend_unregister(&helper_extend);
211         nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_vmalloc,
212                              nf_ct_helper_hsize);
213 }