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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 *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 | |
27 | for (i = 0; i < NF_CT_EXT_NUM; i++) { |
28 | if (!nf_ct_ext_exist(ct, i)) |
29 | continue; |
30 | |
31 | rcu_read_lock(); |
32 | t = rcu_dereference(nf_ct_ext_types[i]); |
33 | |
34 | /* Here the nf_ct_ext_type might have been unregisterd. |
35 | * I.e., it has responsible to cleanup private |
36 | * area in all conntracks when it is unregisterd. |
37 | */ |
38 | if (t && t->destroy) |
39 | t->destroy(ct); |
40 | rcu_read_unlock(); |
41 | } |
42 | } |
43 | EXPORT_SYMBOL(__nf_ct_ext_destroy); |
44 | |
45 | static void * |
46 | nf_ct_ext_create(struct nf_ct_ext **ext, enum nf_ct_ext_id id, gfp_t gfp) |
47 | { |
48 | unsigned int off, len; |
49 | struct nf_ct_ext_type *t; |
50 | |
51 | rcu_read_lock(); |
52 | t = rcu_dereference(nf_ct_ext_types[id]); |
53 | BUG_ON(t == NULL); |
54 | off = ALIGN(sizeof(struct nf_ct_ext), t->align); |
55 | len = off + t->len; |
56 | rcu_read_unlock(); |
57 | |
58 | *ext = kzalloc(t->alloc_size, gfp); |
59 | if (!*ext) |
60 | return NULL; |
61 | |
62 | (*ext)->offset[id] = off; |
63 | (*ext)->len = len; |
64 | |
65 | return (void *)(*ext) + off; |
66 | } |
67 | |
68 | static void __nf_ct_ext_free_rcu(struct rcu_head *head) |
69 | { |
70 | struct nf_ct_ext *ext = container_of(head, struct nf_ct_ext, rcu); |
71 | kfree(ext); |
72 | } |
73 | |
74 | void *__nf_ct_ext_add(struct nf_conn *ct, enum nf_ct_ext_id id, gfp_t gfp) |
75 | { |
76 | struct nf_ct_ext *new; |
77 | int i, newlen, newoff; |
78 | struct nf_ct_ext_type *t; |
79 | |
80 | /* Conntrack must not be confirmed to avoid races on reallocation. */ |
81 | NF_CT_ASSERT(!nf_ct_is_confirmed(ct)); |
82 | |
83 | if (!ct->ext) |
84 | return nf_ct_ext_create(&ct->ext, id, gfp); |
85 | |
86 | if (nf_ct_ext_exist(ct, 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(ct->ext->len, t->align); |
94 | newlen = newoff + t->len; |
95 | rcu_read_unlock(); |
96 | |
97 | new = __krealloc(ct->ext, newlen, gfp); |
98 | if (!new) |
99 | return NULL; |
100 | |
101 | if (new != ct->ext) { |
102 | for (i = 0; i < NF_CT_EXT_NUM; i++) { |
103 | if (!nf_ct_ext_exist(ct, 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 *)ct->ext + ct->ext->offset[i]); |
111 | rcu_read_unlock(); |
112 | } |
113 | call_rcu(&ct->ext->rcu, __nf_ct_ext_free_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); |
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 = nf_ct_ext_types[i]; |
140 | if (!t1) |
141 | continue; |
142 | |
143 | t1->alloc_size = sizeof(struct nf_ct_ext) |
144 | + ALIGN(sizeof(struct nf_ct_ext), t1->align) |
145 | + t1->len; |
146 | for (j = 0; j < NF_CT_EXT_NUM; j++) { |
147 | t2 = nf_ct_ext_types[j]; |
148 | if (t2 == NULL || t2 == t1 || |
149 | (t2->flags & NF_CT_EXT_F_PREALLOC) == 0) |
150 | continue; |
151 | |
152 | t1->alloc_size = ALIGN(t1->alloc_size, t2->align) |
153 | + t2->len; |
154 | } |
155 | } |
156 | } |
157 | |
158 | /* This MUST be called in process context. */ |
159 | int nf_ct_extend_register(struct nf_ct_ext_type *type) |
160 | { |
161 | int ret = 0; |
162 | |
163 | mutex_lock(&nf_ct_ext_type_mutex); |
164 | if (nf_ct_ext_types[type->id]) { |
165 | ret = -EBUSY; |
166 | goto out; |
167 | } |
168 | |
169 | /* This ensures that nf_ct_ext_create() can allocate enough area |
170 | before updating alloc_size */ |
171 | type->alloc_size = ALIGN(sizeof(struct nf_ct_ext), type->align) |
172 | + type->len; |
173 | rcu_assign_pointer(nf_ct_ext_types[type->id], type); |
174 | update_alloc_size(type); |
175 | out: |
176 | mutex_unlock(&nf_ct_ext_type_mutex); |
177 | return ret; |
178 | } |
179 | EXPORT_SYMBOL_GPL(nf_ct_extend_register); |
180 | |
181 | /* This MUST be called in process context. */ |
182 | void nf_ct_extend_unregister(struct nf_ct_ext_type *type) |
183 | { |
184 | mutex_lock(&nf_ct_ext_type_mutex); |
185 | rcu_assign_pointer(nf_ct_ext_types[type->id], NULL); |
186 | update_alloc_size(type); |
187 | mutex_unlock(&nf_ct_ext_type_mutex); |
188 | rcu_barrier(); /* Wait for completion of call_rcu()'s */ |
189 | } |
190 | EXPORT_SYMBOL_GPL(nf_ct_extend_unregister); |
191 |
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