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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 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 | kfree_rcu(old, rcu); | |
103 | rcu_assign_pointer(ct->ext, new); | |
104 | } | |
105 | ||
106 | new->offset[id] = newoff; | |
107 | new->len = newlen; | |
108 | memset((void *)new + newoff, 0, newlen - newoff); | |
109 | return (void *)new + newoff; | |
110 | } | |
111 | EXPORT_SYMBOL(__nf_ct_ext_add_length); | |
112 | ||
113 | static void update_alloc_size(struct nf_ct_ext_type *type) | |
114 | { | |
115 | int i, j; | |
116 | struct nf_ct_ext_type *t1, *t2; | |
117 | enum nf_ct_ext_id min = 0, max = NF_CT_EXT_NUM - 1; | |
118 | ||
119 | /* unnecessary to update all types */ | |
120 | if ((type->flags & NF_CT_EXT_F_PREALLOC) == 0) { | |
121 | min = type->id; | |
122 | max = type->id; | |
123 | } | |
124 | ||
125 | /* This assumes that extended areas in conntrack for the types | |
126 | whose NF_CT_EXT_F_PREALLOC bit set are allocated in order */ | |
127 | for (i = min; i <= max; i++) { | |
128 | t1 = rcu_dereference_protected(nf_ct_ext_types[i], | |
129 | lockdep_is_held(&nf_ct_ext_type_mutex)); | |
130 | if (!t1) | |
131 | continue; | |
132 | ||
133 | t1->alloc_size = ALIGN(sizeof(struct nf_ct_ext), t1->align) + | |
134 | t1->len; | |
135 | for (j = 0; j < NF_CT_EXT_NUM; j++) { | |
136 | t2 = rcu_dereference_protected(nf_ct_ext_types[j], | |
137 | lockdep_is_held(&nf_ct_ext_type_mutex)); | |
138 | if (t2 == NULL || t2 == t1 || | |
139 | (t2->flags & NF_CT_EXT_F_PREALLOC) == 0) | |
140 | continue; | |
141 | ||
142 | t1->alloc_size = ALIGN(t1->alloc_size, t2->align) | |
143 | + t2->len; | |
144 | } | |
145 | } | |
146 | } | |
147 | ||
148 | /* This MUST be called in process context. */ | |
149 | int nf_ct_extend_register(struct nf_ct_ext_type *type) | |
150 | { | |
151 | int ret = 0; | |
152 | ||
153 | mutex_lock(&nf_ct_ext_type_mutex); | |
154 | if (nf_ct_ext_types[type->id]) { | |
155 | ret = -EBUSY; | |
156 | goto out; | |
157 | } | |
158 | ||
159 | /* This ensures that nf_ct_ext_create() can allocate enough area | |
160 | before updating alloc_size */ | |
161 | type->alloc_size = ALIGN(sizeof(struct nf_ct_ext), type->align) | |
162 | + type->len; | |
163 | rcu_assign_pointer(nf_ct_ext_types[type->id], type); | |
164 | update_alloc_size(type); | |
165 | out: | |
166 | mutex_unlock(&nf_ct_ext_type_mutex); | |
167 | return ret; | |
168 | } | |
169 | EXPORT_SYMBOL_GPL(nf_ct_extend_register); | |
170 | ||
171 | /* This MUST be called in process context. */ | |
172 | void nf_ct_extend_unregister(struct nf_ct_ext_type *type) | |
173 | { | |
174 | mutex_lock(&nf_ct_ext_type_mutex); | |
175 | RCU_INIT_POINTER(nf_ct_ext_types[type->id], NULL); | |
176 | update_alloc_size(type); | |
177 | mutex_unlock(&nf_ct_ext_type_mutex); | |
178 | rcu_barrier(); /* Wait for completion of call_rcu()'s */ | |
179 | } | |
180 | EXPORT_SYMBOL_GPL(nf_ct_extend_unregister); |