netfilter: netns nf_conntrack: per-netns conntrack hash
[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
25 #include <net/netfilter/nf_conntrack.h>
26 #include <net/netfilter/nf_conntrack_l3proto.h>
27 #include <net/netfilter/nf_conntrack_l4proto.h>
28 #include <net/netfilter/nf_conntrack_helper.h>
29 #include <net/netfilter/nf_conntrack_core.h>
30 #include <net/netfilter/nf_conntrack_extend.h>
31
32 static DEFINE_MUTEX(nf_ct_helper_mutex);
33 static struct hlist_head *nf_ct_helper_hash __read_mostly;
34 static unsigned int nf_ct_helper_hsize __read_mostly;
35 static unsigned int nf_ct_helper_count __read_mostly;
36 static int nf_ct_helper_vmalloc;
37
38
39 /* Stupid hash, but collision free for the default registrations of the
40  * helpers currently in the kernel. */
41 static unsigned int helper_hash(const struct nf_conntrack_tuple *tuple)
42 {
43         return (((tuple->src.l3num << 8) | tuple->dst.protonum) ^
44                 (__force __u16)tuple->src.u.all) % nf_ct_helper_hsize;
45 }
46
47 struct nf_conntrack_helper *
48 __nf_ct_helper_find(const struct nf_conntrack_tuple *tuple)
49 {
50         struct nf_conntrack_helper *helper;
51         struct nf_conntrack_tuple_mask mask = { .src.u.all = htons(0xFFFF) };
52         struct hlist_node *n;
53         unsigned int h;
54
55         if (!nf_ct_helper_count)
56                 return NULL;
57
58         h = helper_hash(tuple);
59         hlist_for_each_entry_rcu(helper, n, &nf_ct_helper_hash[h], hnode) {
60                 if (nf_ct_tuple_src_mask_cmp(tuple, &helper->tuple, &mask))
61                         return helper;
62         }
63         return NULL;
64 }
65 EXPORT_SYMBOL_GPL(__nf_ct_helper_find);
66
67 struct nf_conntrack_helper *
68 __nf_conntrack_helper_find_byname(const char *name)
69 {
70         struct nf_conntrack_helper *h;
71         struct hlist_node *n;
72         unsigned int i;
73
74         for (i = 0; i < nf_ct_helper_hsize; i++) {
75                 hlist_for_each_entry_rcu(h, n, &nf_ct_helper_hash[i], hnode) {
76                         if (!strcmp(h->name, name))
77                                 return h;
78                 }
79         }
80         return NULL;
81 }
82 EXPORT_SYMBOL_GPL(__nf_conntrack_helper_find_byname);
83
84 struct nf_conn_help *nf_ct_helper_ext_add(struct nf_conn *ct, gfp_t gfp)
85 {
86         struct nf_conn_help *help;
87
88         help = nf_ct_ext_add(ct, NF_CT_EXT_HELPER, gfp);
89         if (help)
90                 INIT_HLIST_HEAD(&help->expectations);
91         else
92                 pr_debug("failed to add helper extension area");
93         return help;
94 }
95 EXPORT_SYMBOL_GPL(nf_ct_helper_ext_add);
96
97 static inline int unhelp(struct nf_conntrack_tuple_hash *i,
98                          const struct nf_conntrack_helper *me)
99 {
100         struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(i);
101         struct nf_conn_help *help = nfct_help(ct);
102
103         if (help && help->helper == me) {
104                 nf_conntrack_event(IPCT_HELPER, ct);
105                 rcu_assign_pointer(help->helper, NULL);
106         }
107         return 0;
108 }
109
110 int nf_conntrack_helper_register(struct nf_conntrack_helper *me)
111 {
112         unsigned int h = helper_hash(&me->tuple);
113
114         BUG_ON(me->expect_policy == NULL);
115         BUG_ON(me->expect_class_max >= NF_CT_MAX_EXPECT_CLASSES);
116
117         mutex_lock(&nf_ct_helper_mutex);
118         hlist_add_head_rcu(&me->hnode, &nf_ct_helper_hash[h]);
119         nf_ct_helper_count++;
120         mutex_unlock(&nf_ct_helper_mutex);
121
122         return 0;
123 }
124 EXPORT_SYMBOL_GPL(nf_conntrack_helper_register);
125
126 void nf_conntrack_helper_unregister(struct nf_conntrack_helper *me)
127 {
128         struct nf_conntrack_tuple_hash *h;
129         struct nf_conntrack_expect *exp;
130         const struct hlist_node *n, *next;
131         unsigned int i;
132
133         mutex_lock(&nf_ct_helper_mutex);
134         hlist_del_rcu(&me->hnode);
135         nf_ct_helper_count--;
136         mutex_unlock(&nf_ct_helper_mutex);
137
138         /* Make sure every nothing is still using the helper unless its a
139          * connection in the hash.
140          */
141         synchronize_rcu();
142
143         spin_lock_bh(&nf_conntrack_lock);
144
145         /* Get rid of expectations */
146         for (i = 0; i < nf_ct_expect_hsize; i++) {
147                 hlist_for_each_entry_safe(exp, n, next,
148                                           &nf_ct_expect_hash[i], hnode) {
149                         struct nf_conn_help *help = nfct_help(exp->master);
150                         if ((help->helper == me || exp->helper == me) &&
151                             del_timer(&exp->timeout)) {
152                                 nf_ct_unlink_expect(exp);
153                                 nf_ct_expect_put(exp);
154                         }
155                 }
156         }
157
158         /* Get rid of expecteds, set helpers to NULL. */
159         hlist_for_each_entry(h, n, &unconfirmed, hnode)
160                 unhelp(h, me);
161         for (i = 0; i < nf_conntrack_htable_size; i++) {
162                 hlist_for_each_entry(h, n, &init_net.ct.hash[i], hnode)
163                         unhelp(h, me);
164         }
165         spin_unlock_bh(&nf_conntrack_lock);
166 }
167 EXPORT_SYMBOL_GPL(nf_conntrack_helper_unregister);
168
169 static struct nf_ct_ext_type helper_extend __read_mostly = {
170         .len    = sizeof(struct nf_conn_help),
171         .align  = __alignof__(struct nf_conn_help),
172         .id     = NF_CT_EXT_HELPER,
173 };
174
175 int nf_conntrack_helper_init(void)
176 {
177         int err;
178
179         nf_ct_helper_hsize = 1; /* gets rounded up to use one page */
180         nf_ct_helper_hash = nf_ct_alloc_hashtable(&nf_ct_helper_hsize,
181                                                   &nf_ct_helper_vmalloc);
182         if (!nf_ct_helper_hash)
183                 return -ENOMEM;
184
185         err = nf_ct_extend_register(&helper_extend);
186         if (err < 0)
187                 goto err1;
188
189         return 0;
190
191 err1:
192         nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_vmalloc,
193                              nf_ct_helper_hsize);
194         return err;
195 }
196
197 void nf_conntrack_helper_fini(void)
198 {
199         nf_ct_extend_unregister(&helper_extend);
200         nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_vmalloc,
201                              nf_ct_helper_hsize);
202 }