1 /* Structure dynamic extension infrastructure
2 * Copyright (C) 2004 Rusty Russell IBM Corporation
3 * Copyright (C) 2007 Netfilter Core Team <coreteam@netfilter.org>
4 * Copyright (C) 2007 USAGI/WIDE Project <http://www.linux-ipv6.org>
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11 #include <linux/kernel.h>
12 #include <linux/module.h>
13 #include <linux/mutex.h>
14 #include <linux/rcupdate.h>
15 #include <linux/slab.h>
16 #include <linux/skbuff.h>
17 #include <net/netfilter/nf_conntrack_extend.h>
18
19 static struct nf_ct_ext_type __rcu *nf_ct_ext_types[NF_CT_EXT_NUM];
20 static DEFINE_MUTEX(nf_ct_ext_type_mutex);
21
__nf_ct_ext_destroy(struct nf_conn * ct)22 void __nf_ct_ext_destroy(struct nf_conn *ct)
23 {
24 unsigned int i;
25 struct nf_ct_ext_type *t;
26 struct nf_ct_ext *ext = ct->ext;
27
28 for (i = 0; i < NF_CT_EXT_NUM; i++) {
29 if (!__nf_ct_ext_exist(ext, i))
30 continue;
31
32 rcu_read_lock();
33 t = rcu_dereference(nf_ct_ext_types[i]);
34
35 /* Here the nf_ct_ext_type might have been unregisterd.
36 * I.e., it has responsible to cleanup private
37 * area in all conntracks when it is unregisterd.
38 */
39 if (t && t->destroy)
40 t->destroy(ct);
41 rcu_read_unlock();
42 }
43 }
44 EXPORT_SYMBOL(__nf_ct_ext_destroy);
45
46 static void *
nf_ct_ext_create(struct nf_ct_ext ** ext,enum nf_ct_ext_id id,gfp_t gfp)47 nf_ct_ext_create(struct nf_ct_ext **ext, enum nf_ct_ext_id id, gfp_t gfp)
48 {
49 unsigned int off, len;
50 struct nf_ct_ext_type *t;
51 size_t alloc_size;
52
53 rcu_read_lock();
54 t = rcu_dereference(nf_ct_ext_types[id]);
55 BUG_ON(t == NULL);
56 off = ALIGN(sizeof(struct nf_ct_ext), t->align);
57 len = off + t->len;
58 alloc_size = t->alloc_size;
59 rcu_read_unlock();
60
61 *ext = kzalloc(alloc_size, gfp);
62 if (!*ext)
63 return NULL;
64
65 (*ext)->offset[id] = off;
66 (*ext)->len = len;
67
68 return (void *)(*ext) + off;
69 }
70
__nf_ct_ext_add(struct nf_conn * ct,enum nf_ct_ext_id id,gfp_t gfp)71 void *__nf_ct_ext_add(struct nf_conn *ct, enum nf_ct_ext_id id, gfp_t gfp)
72 {
73 struct nf_ct_ext *old, *new;
74 int i, newlen, newoff;
75 struct nf_ct_ext_type *t;
76
77 /* Conntrack must not be confirmed to avoid races on reallocation. */
78 NF_CT_ASSERT(!nf_ct_is_confirmed(ct));
79
80 old = ct->ext;
81 if (!old)
82 return nf_ct_ext_create(&ct->ext, id, gfp);
83
84 if (__nf_ct_ext_exist(old, id))
85 return NULL;
86
87 rcu_read_lock();
88 t = rcu_dereference(nf_ct_ext_types[id]);
89 BUG_ON(t == NULL);
90
91 newoff = ALIGN(old->len, t->align);
92 newlen = newoff + t->len;
93 rcu_read_unlock();
94
95 new = __krealloc(old, newlen, gfp);
96 if (!new)
97 return NULL;
98
99 if (new != old) {
100 for (i = 0; i < NF_CT_EXT_NUM; i++) {
101 if (!__nf_ct_ext_exist(old, i))
102 continue;
103
104 rcu_read_lock();
105 t = rcu_dereference(nf_ct_ext_types[i]);
106 if (t && t->move)
107 t->move((void *)new + new->offset[i],
108 (void *)old + old->offset[i]);
109 rcu_read_unlock();
110 }
111 kfree_rcu(old, rcu);
112 ct->ext = new;
113 }
114
115 new->offset[id] = newoff;
116 new->len = newlen;
117 memset((void *)new + newoff, 0, newlen - newoff);
118 return (void *)new + newoff;
119 }
120 EXPORT_SYMBOL(__nf_ct_ext_add);
121
update_alloc_size(struct nf_ct_ext_type * type)122 static void update_alloc_size(struct nf_ct_ext_type *type)
123 {
124 int i, j;
125 struct nf_ct_ext_type *t1, *t2;
126 enum nf_ct_ext_id min = 0, max = NF_CT_EXT_NUM - 1;
127
128 /* unnecessary to update all types */
129 if ((type->flags & NF_CT_EXT_F_PREALLOC) == 0) {
130 min = type->id;
131 max = type->id;
132 }
133
134 /* This assumes that extended areas in conntrack for the types
135 whose NF_CT_EXT_F_PREALLOC bit set are allocated in order */
136 for (i = min; i <= max; i++) {
137 t1 = rcu_dereference_protected(nf_ct_ext_types[i],
138 lockdep_is_held(&nf_ct_ext_type_mutex));
139 if (!t1)
140 continue;
141
142 t1->alloc_size = ALIGN(sizeof(struct nf_ct_ext), t1->align) +
143 t1->len;
144 for (j = 0; j < NF_CT_EXT_NUM; j++) {
145 t2 = rcu_dereference_protected(nf_ct_ext_types[j],
146 lockdep_is_held(&nf_ct_ext_type_mutex));
147 if (t2 == NULL || t2 == t1 ||
148 (t2->flags & NF_CT_EXT_F_PREALLOC) == 0)
149 continue;
150
151 t1->alloc_size = ALIGN(t1->alloc_size, t2->align)
152 + t2->len;
153 }
154 }
155 }
156
157 /* This MUST be called in process context. */
nf_ct_extend_register(struct nf_ct_ext_type * type)158 int nf_ct_extend_register(struct nf_ct_ext_type *type)
159 {
160 int ret = 0;
161
162 mutex_lock(&nf_ct_ext_type_mutex);
163 if (nf_ct_ext_types[type->id]) {
164 ret = -EBUSY;
165 goto out;
166 }
167
168 /* This ensures that nf_ct_ext_create() can allocate enough area
169 before updating alloc_size */
170 type->alloc_size = ALIGN(sizeof(struct nf_ct_ext), type->align)
171 + type->len;
172 rcu_assign_pointer(nf_ct_ext_types[type->id], type);
173 update_alloc_size(type);
174 out:
175 mutex_unlock(&nf_ct_ext_type_mutex);
176 return ret;
177 }
178 EXPORT_SYMBOL_GPL(nf_ct_extend_register);
179
180 /* This MUST be called in process context. */
nf_ct_extend_unregister(struct nf_ct_ext_type * type)181 void nf_ct_extend_unregister(struct nf_ct_ext_type *type)
182 {
183 mutex_lock(&nf_ct_ext_type_mutex);
184 RCU_INIT_POINTER(nf_ct_ext_types[type->id], NULL);
185 update_alloc_size(type);
186 mutex_unlock(&nf_ct_ext_type_mutex);
187 rcu_barrier(); /* Wait for completion of call_rcu()'s */
188 }
189 EXPORT_SYMBOL_GPL(nf_ct_extend_unregister);
190