1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* Structure dynamic extension infrastructure
3 * Copyright (C) 2004 Rusty Russell IBM Corporation
4 * Copyright (C) 2007 Netfilter Core Team <coreteam@netfilter.org>
5 * Copyright (C) 2007 USAGI/WIDE Project <http://www.linux-ipv6.org>
6 */
7 #include <linux/kernel.h>
8 #include <linux/kmemleak.h>
9 #include <linux/module.h>
10 #include <linux/mutex.h>
11 #include <linux/rcupdate.h>
12 #include <linux/slab.h>
13 #include <linux/skbuff.h>
14 #include <net/netfilter/nf_conntrack_extend.h>
15
16 static struct nf_ct_ext_type __rcu *nf_ct_ext_types[NF_CT_EXT_NUM];
17 static DEFINE_MUTEX(nf_ct_ext_type_mutex);
18 #define NF_CT_EXT_PREALLOC 128u /* conntrack events are on by default */
19
nf_ct_ext_destroy(struct nf_conn * ct)20 void nf_ct_ext_destroy(struct nf_conn *ct)
21 {
22 unsigned int i;
23 struct nf_ct_ext_type *t;
24
25 for (i = 0; i < NF_CT_EXT_NUM; i++) {
26 rcu_read_lock();
27 t = rcu_dereference(nf_ct_ext_types[i]);
28
29 /* Here the nf_ct_ext_type might have been unregisterd.
30 * I.e., it has responsible to cleanup private
31 * area in all conntracks when it is unregisterd.
32 */
33 if (t && t->destroy)
34 t->destroy(ct);
35 rcu_read_unlock();
36 }
37
38 kfree(ct->ext);
39 }
40
nf_ct_ext_add(struct nf_conn * ct,enum nf_ct_ext_id id,gfp_t gfp)41 void *nf_ct_ext_add(struct nf_conn *ct, enum nf_ct_ext_id id, gfp_t gfp)
42 {
43 unsigned int newlen, newoff, oldlen, alloc;
44 struct nf_ct_ext_type *t;
45 struct nf_ct_ext *new;
46
47 /* Conntrack must not be confirmed to avoid races on reallocation. */
48 WARN_ON(nf_ct_is_confirmed(ct));
49
50
51 if (ct->ext) {
52 const struct nf_ct_ext *old = ct->ext;
53
54 if (__nf_ct_ext_exist(old, id))
55 return NULL;
56 oldlen = old->len;
57 } else {
58 oldlen = sizeof(*new);
59 }
60
61 rcu_read_lock();
62 t = rcu_dereference(nf_ct_ext_types[id]);
63 if (!t) {
64 rcu_read_unlock();
65 return NULL;
66 }
67
68 newoff = ALIGN(oldlen, t->align);
69 newlen = newoff + t->len;
70 rcu_read_unlock();
71
72 alloc = max(newlen, NF_CT_EXT_PREALLOC);
73 new = krealloc(ct->ext, alloc, gfp);
74 if (!new)
75 return NULL;
76
77 if (!ct->ext)
78 memset(new->offset, 0, sizeof(new->offset));
79
80 new->offset[id] = newoff;
81 new->len = newlen;
82 memset((void *)new + newoff, 0, newlen - newoff);
83
84 ct->ext = new;
85 return (void *)new + newoff;
86 }
87 EXPORT_SYMBOL(nf_ct_ext_add);
88
89 /* This MUST be called in process context. */
nf_ct_extend_register(const struct nf_ct_ext_type * type)90 int nf_ct_extend_register(const struct nf_ct_ext_type *type)
91 {
92 int ret = 0;
93
94 mutex_lock(&nf_ct_ext_type_mutex);
95 if (nf_ct_ext_types[type->id]) {
96 ret = -EBUSY;
97 goto out;
98 }
99
100 rcu_assign_pointer(nf_ct_ext_types[type->id], type);
101 out:
102 mutex_unlock(&nf_ct_ext_type_mutex);
103 return ret;
104 }
105 EXPORT_SYMBOL_GPL(nf_ct_extend_register);
106
107 /* This MUST be called in process context. */
nf_ct_extend_unregister(const struct nf_ct_ext_type * type)108 void nf_ct_extend_unregister(const struct nf_ct_ext_type *type)
109 {
110 mutex_lock(&nf_ct_ext_type_mutex);
111 RCU_INIT_POINTER(nf_ct_ext_types[type->id], NULL);
112 mutex_unlock(&nf_ct_ext_type_mutex);
113 synchronize_rcu();
114 }
115 EXPORT_SYMBOL_GPL(nf_ct_extend_unregister);
116