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 EXPORT_SYMBOL(nf_ct_ext_destroy);
39
nf_ct_ext_add(struct nf_conn * ct,enum nf_ct_ext_id id,gfp_t gfp)40 void *nf_ct_ext_add(struct nf_conn *ct, enum nf_ct_ext_id id, gfp_t gfp)
41 {
42 unsigned int newlen, newoff, oldlen, alloc;
43 struct nf_ct_ext *old, *new;
44 struct nf_ct_ext_type *t;
45
46 /* Conntrack must not be confirmed to avoid races on reallocation. */
47 WARN_ON(nf_ct_is_confirmed(ct));
48
49 old = ct->ext;
50
51 if (old) {
52 if (__nf_ct_ext_exist(old, id))
53 return NULL;
54 oldlen = old->len;
55 } else {
56 oldlen = sizeof(*new);
57 }
58
59 rcu_read_lock();
60 t = rcu_dereference(nf_ct_ext_types[id]);
61 if (!t) {
62 rcu_read_unlock();
63 return NULL;
64 }
65
66 newoff = ALIGN(oldlen, t->align);
67 newlen = newoff + t->len;
68 rcu_read_unlock();
69
70 alloc = max(newlen, NF_CT_EXT_PREALLOC);
71 kmemleak_not_leak(old);
72 new = __krealloc(old, alloc, gfp);
73 if (!new)
74 return NULL;
75
76 if (!old) {
77 memset(new->offset, 0, sizeof(new->offset));
78 ct->ext = new;
79 } else if (new != old) {
80 kfree_rcu(old, rcu);
81 rcu_assign_pointer(ct->ext, new);
82 }
83
84 new->offset[id] = newoff;
85 new->len = newlen;
86 memset((void *)new + newoff, 0, newlen - newoff);
87 return (void *)new + newoff;
88 }
89 EXPORT_SYMBOL(nf_ct_ext_add);
90
91 /* This MUST be called in process context. */
nf_ct_extend_register(const struct nf_ct_ext_type * type)92 int nf_ct_extend_register(const struct nf_ct_ext_type *type)
93 {
94 int ret = 0;
95
96 mutex_lock(&nf_ct_ext_type_mutex);
97 if (nf_ct_ext_types[type->id]) {
98 ret = -EBUSY;
99 goto out;
100 }
101
102 rcu_assign_pointer(nf_ct_ext_types[type->id], type);
103 out:
104 mutex_unlock(&nf_ct_ext_type_mutex);
105 return ret;
106 }
107 EXPORT_SYMBOL_GPL(nf_ct_extend_register);
108
109 /* This MUST be called in process context. */
nf_ct_extend_unregister(const struct nf_ct_ext_type * type)110 void nf_ct_extend_unregister(const struct nf_ct_ext_type *type)
111 {
112 mutex_lock(&nf_ct_ext_type_mutex);
113 RCU_INIT_POINTER(nf_ct_ext_types[type->id], NULL);
114 mutex_unlock(&nf_ct_ext_type_mutex);
115 synchronize_rcu();
116 }
117 EXPORT_SYMBOL_GPL(nf_ct_extend_unregister);
118