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ecfab2c9 YK |
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 *nf_ct_ext_types[NF_CT_EXT_NUM]; | |
20 | static DEFINE_MUTEX(nf_ct_ext_type_mutex); | |
21 | ||
22 | /* Horrible trick to figure out smallest amount worth kmallocing. */ | |
23 | #define CACHE(x) (x) + 0 * | |
24 | enum { | |
25 | NF_CT_EXT_MIN_SIZE = | |
26 | #include <linux/kmalloc_sizes.h> | |
27 | 1 }; | |
28 | #undef CACHE | |
29 | ||
30 | void __nf_ct_ext_destroy(struct nf_conn *ct) | |
31 | { | |
32 | unsigned int i; | |
33 | struct nf_ct_ext_type *t; | |
34 | ||
35 | for (i = 0; i < NF_CT_EXT_NUM; i++) { | |
36 | if (!nf_ct_ext_exist(ct, i)) | |
37 | continue; | |
38 | ||
39 | rcu_read_lock(); | |
40 | t = rcu_dereference(nf_ct_ext_types[i]); | |
41 | ||
42 | /* Here the nf_ct_ext_type might have been unregisterd. | |
43 | * I.e., it has responsible to cleanup private | |
44 | * area in all conntracks when it is unregisterd. | |
45 | */ | |
46 | if (t && t->destroy) | |
47 | t->destroy(ct); | |
48 | rcu_read_unlock(); | |
49 | } | |
50 | } | |
51 | EXPORT_SYMBOL(__nf_ct_ext_destroy); | |
52 | ||
53 | static void * | |
54 | nf_ct_ext_create(struct nf_ct_ext **ext, enum nf_ct_ext_id id, gfp_t gfp) | |
55 | { | |
56 | unsigned int off, len, real_len; | |
57 | struct nf_ct_ext_type *t; | |
58 | ||
59 | rcu_read_lock(); | |
60 | t = rcu_dereference(nf_ct_ext_types[id]); | |
61 | BUG_ON(t == NULL); | |
62 | off = ALIGN(sizeof(struct nf_ct_ext), t->align); | |
63 | len = off + t->len; | |
64 | real_len = t->alloc_size; | |
65 | rcu_read_unlock(); | |
66 | ||
67 | *ext = kzalloc(real_len, gfp); | |
68 | if (!*ext) | |
69 | return NULL; | |
70 | ||
71 | (*ext)->offset[id] = off; | |
72 | (*ext)->len = len; | |
73 | (*ext)->real_len = real_len; | |
74 | ||
75 | return (void *)(*ext) + off; | |
76 | } | |
77 | ||
78 | void *__nf_ct_ext_add(struct nf_conn *ct, enum nf_ct_ext_id id, gfp_t gfp) | |
79 | { | |
80 | struct nf_ct_ext *new; | |
81 | int i, newlen, newoff; | |
82 | struct nf_ct_ext_type *t; | |
83 | ||
84 | if (!ct->ext) | |
85 | return nf_ct_ext_create(&ct->ext, id, gfp); | |
86 | ||
87 | if (nf_ct_ext_exist(ct, id)) | |
88 | return NULL; | |
89 | ||
90 | rcu_read_lock(); | |
91 | t = rcu_dereference(nf_ct_ext_types[id]); | |
92 | BUG_ON(t == NULL); | |
93 | ||
94 | newoff = ALIGN(ct->ext->len, t->align); | |
95 | newlen = newoff + t->len; | |
96 | rcu_read_unlock(); | |
97 | ||
98 | if (newlen >= ct->ext->real_len) { | |
99 | new = kmalloc(newlen, gfp); | |
100 | if (!new) | |
101 | return NULL; | |
102 | ||
103 | memcpy(new, ct->ext, ct->ext->len); | |
104 | ||
105 | for (i = 0; i < NF_CT_EXT_NUM; i++) { | |
106 | if (!nf_ct_ext_exist(ct, i)) | |
107 | continue; | |
108 | ||
109 | rcu_read_lock(); | |
110 | t = rcu_dereference(nf_ct_ext_types[i]); | |
111 | if (t && t->move) | |
112 | t->move(ct, ct->ext + ct->ext->offset[id]); | |
113 | rcu_read_unlock(); | |
114 | } | |
115 | kfree(ct->ext); | |
116 | new->real_len = newlen; | |
117 | ct->ext = new; | |
118 | } | |
119 | ||
120 | ct->ext->offset[id] = newoff; | |
121 | ct->ext->len = newlen; | |
122 | memset((void *)ct->ext + newoff, 0, newlen - newoff); | |
123 | return (void *)ct->ext + newoff; | |
124 | } | |
125 | EXPORT_SYMBOL(__nf_ct_ext_add); | |
126 | ||
127 | static void update_alloc_size(struct nf_ct_ext_type *type) | |
128 | { | |
129 | int i, j; | |
130 | struct nf_ct_ext_type *t1, *t2; | |
131 | enum nf_ct_ext_id min = 0, max = NF_CT_EXT_NUM - 1; | |
132 | ||
133 | /* unnecessary to update all types */ | |
134 | if ((type->flags & NF_CT_EXT_F_PREALLOC) == 0) { | |
135 | min = type->id; | |
136 | max = type->id; | |
137 | } | |
138 | ||
139 | /* This assumes that extended areas in conntrack for the types | |
140 | whose NF_CT_EXT_F_PREALLOC bit set are allocated in order */ | |
141 | for (i = min; i <= max; i++) { | |
142 | t1 = nf_ct_ext_types[i]; | |
143 | if (!t1) | |
144 | continue; | |
145 | ||
146 | t1->alloc_size = sizeof(struct nf_ct_ext) | |
147 | + ALIGN(sizeof(struct nf_ct_ext), t1->align) | |
148 | + t1->len; | |
149 | for (j = 0; j < NF_CT_EXT_NUM; j++) { | |
150 | t2 = nf_ct_ext_types[j]; | |
151 | if (t2 == NULL || t2 == t1 || | |
152 | (t2->flags & NF_CT_EXT_F_PREALLOC) == 0) | |
153 | continue; | |
154 | ||
155 | t1->alloc_size = ALIGN(t1->alloc_size, t2->align) | |
156 | + t2->len; | |
157 | } | |
158 | if (t1->alloc_size < NF_CT_EXT_MIN_SIZE) | |
159 | t1->alloc_size = NF_CT_EXT_MIN_SIZE; | |
160 | } | |
161 | } | |
162 | ||
163 | /* This MUST be called in process context. */ | |
164 | int nf_ct_extend_register(struct nf_ct_ext_type *type) | |
165 | { | |
166 | int ret = 0; | |
167 | ||
168 | mutex_lock(&nf_ct_ext_type_mutex); | |
169 | if (nf_ct_ext_types[type->id]) { | |
170 | ret = -EBUSY; | |
171 | goto out; | |
172 | } | |
173 | ||
174 | /* This ensures that nf_ct_ext_create() can allocate enough area | |
175 | before updating alloc_size */ | |
176 | type->alloc_size = ALIGN(sizeof(struct nf_ct_ext), type->align) | |
177 | + type->len; | |
178 | rcu_assign_pointer(nf_ct_ext_types[type->id], type); | |
179 | update_alloc_size(type); | |
180 | out: | |
181 | mutex_unlock(&nf_ct_ext_type_mutex); | |
182 | return ret; | |
183 | } | |
184 | EXPORT_SYMBOL_GPL(nf_ct_extend_register); | |
185 | ||
186 | /* This MUST be called in process context. */ | |
187 | void nf_ct_extend_unregister(struct nf_ct_ext_type *type) | |
188 | { | |
189 | mutex_lock(&nf_ct_ext_type_mutex); | |
190 | rcu_assign_pointer(nf_ct_ext_types[type->id], NULL); | |
191 | update_alloc_size(type); | |
192 | mutex_unlock(&nf_ct_ext_type_mutex); | |
193 | synchronize_rcu(); | |
194 | } | |
195 | EXPORT_SYMBOL_GPL(nf_ct_extend_unregister); |