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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 | |
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 * |
47 | nf_ct_ext_create(struct nf_ct_ext **ext, enum nf_ct_ext_id id, |
48 | size_t var_alloc_len, gfp_t gfp) |
49 | { |
50 | unsigned int off, len; |
51 | struct nf_ct_ext_type *t; |
52 | size_t alloc_size; |
53 | |
54 | rcu_read_lock(); |
55 | t = rcu_dereference(nf_ct_ext_types[id]); |
56 | BUG_ON(t == NULL); |
57 | off = ALIGN(sizeof(struct nf_ct_ext), t->align); |
58 | len = off + t->len + var_alloc_len; |
59 | alloc_size = t->alloc_size + var_alloc_len; |
60 | rcu_read_unlock(); |
61 | |
62 | *ext = kzalloc(alloc_size, gfp); |
63 | if (!*ext) |
64 | return NULL; |
65 | |
66 | (*ext)->offset[id] = off; |
67 | (*ext)->len = len; |
68 | |
69 | return (void *)(*ext) + off; |
70 | } |
71 | |
72 | void *__nf_ct_ext_add_length(struct nf_conn *ct, enum nf_ct_ext_id id, |
73 | size_t var_alloc_len, gfp_t gfp) |
74 | { |
75 | struct nf_ct_ext *old, *new; |
76 | int i, newlen, newoff; |
77 | struct nf_ct_ext_type *t; |
78 | |
79 | /* Conntrack must not be confirmed to avoid races on reallocation. */ |
80 | NF_CT_ASSERT(!nf_ct_is_confirmed(ct)); |
81 | |
82 | old = ct->ext; |
83 | if (!old) |
84 | return nf_ct_ext_create(&ct->ext, id, var_alloc_len, gfp); |
85 | |
86 | if (__nf_ct_ext_exist(old, id)) |
87 | return NULL; |
88 | |
89 | rcu_read_lock(); |
90 | t = rcu_dereference(nf_ct_ext_types[id]); |
91 | BUG_ON(t == NULL); |
92 | |
93 | newoff = ALIGN(old->len, t->align); |
94 | newlen = newoff + t->len + var_alloc_len; |
95 | rcu_read_unlock(); |
96 | |
97 | new = __krealloc(old, newlen, gfp); |
98 | if (!new) |
99 | return NULL; |
100 | |
101 | if (new != old) { |
102 | for (i = 0; i < NF_CT_EXT_NUM; i++) { |
103 | if (!__nf_ct_ext_exist(old, i)) |
104 | continue; |
105 | |
106 | rcu_read_lock(); |
107 | t = rcu_dereference(nf_ct_ext_types[i]); |
108 | if (t && t->move) |
109 | t->move((void *)new + new->offset[i], |
110 | (void *)old + old->offset[i]); |
111 | rcu_read_unlock(); |
112 | } |
113 | kfree_rcu(old, rcu); |
114 | ct->ext = new; |
115 | } |
116 | |
117 | new->offset[id] = newoff; |
118 | new->len = newlen; |
119 | memset((void *)new + newoff, 0, newlen - newoff); |
120 | return (void *)new + newoff; |
121 | } |
122 | EXPORT_SYMBOL(__nf_ct_ext_add_length); |
123 | |
124 | static void update_alloc_size(struct nf_ct_ext_type *type) |
125 | { |
126 | int i, j; |
127 | struct nf_ct_ext_type *t1, *t2; |
128 | enum nf_ct_ext_id min = 0, max = NF_CT_EXT_NUM - 1; |
129 | |
130 | /* unnecessary to update all types */ |
131 | if ((type->flags & NF_CT_EXT_F_PREALLOC) == 0) { |
132 | min = type->id; |
133 | max = type->id; |
134 | } |
135 | |
136 | /* This assumes that extended areas in conntrack for the types |
137 | whose NF_CT_EXT_F_PREALLOC bit set are allocated in order */ |
138 | for (i = min; i <= max; i++) { |
139 | t1 = rcu_dereference_protected(nf_ct_ext_types[i], |
140 | lockdep_is_held(&nf_ct_ext_type_mutex)); |
141 | if (!t1) |
142 | continue; |
143 | |
144 | t1->alloc_size = ALIGN(sizeof(struct nf_ct_ext), t1->align) + |
145 | t1->len; |
146 | for (j = 0; j < NF_CT_EXT_NUM; j++) { |
147 | t2 = rcu_dereference_protected(nf_ct_ext_types[j], |
148 | lockdep_is_held(&nf_ct_ext_type_mutex)); |
149 | if (t2 == NULL || t2 == t1 || |
150 | (t2->flags & NF_CT_EXT_F_PREALLOC) == 0) |
151 | continue; |
152 | |
153 | t1->alloc_size = ALIGN(t1->alloc_size, t2->align) |
154 | + t2->len; |
155 | } |
156 | } |
157 | } |
158 | |
159 | /* This MUST be called in process context. */ |
160 | int nf_ct_extend_register(struct nf_ct_ext_type *type) |
161 | { |
162 | int ret = 0; |
163 | |
164 | mutex_lock(&nf_ct_ext_type_mutex); |
165 | if (nf_ct_ext_types[type->id]) { |
166 | ret = -EBUSY; |
167 | goto out; |
168 | } |
169 | |
170 | /* This ensures that nf_ct_ext_create() can allocate enough area |
171 | before updating alloc_size */ |
172 | type->alloc_size = ALIGN(sizeof(struct nf_ct_ext), type->align) |
173 | + type->len; |
174 | rcu_assign_pointer(nf_ct_ext_types[type->id], type); |
175 | update_alloc_size(type); |
176 | out: |
177 | mutex_unlock(&nf_ct_ext_type_mutex); |
178 | return ret; |
179 | } |
180 | EXPORT_SYMBOL_GPL(nf_ct_extend_register); |
181 | |
182 | /* This MUST be called in process context. */ |
183 | void nf_ct_extend_unregister(struct nf_ct_ext_type *type) |
184 | { |
185 | mutex_lock(&nf_ct_ext_type_mutex); |
186 | RCU_INIT_POINTER(nf_ct_ext_types[type->id], NULL); |
187 | update_alloc_size(type); |
188 | mutex_unlock(&nf_ct_ext_type_mutex); |
189 | rcu_barrier(); /* Wait for completion of call_rcu()'s */ |
190 | } |
191 | EXPORT_SYMBOL_GPL(nf_ct_extend_unregister); |
192 |
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