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 #include <net/netfilter/nf_conntrack_helper.h>
17 #include <net/netfilter/nf_conntrack_acct.h>
18 #include <net/netfilter/nf_conntrack_seqadj.h>
19 #include <net/netfilter/nf_conntrack_ecache.h>
20 #include <net/netfilter/nf_conntrack_zones.h>
21 #include <net/netfilter/nf_conntrack_timestamp.h>
22 #include <net/netfilter/nf_conntrack_timeout.h>
23 #include <net/netfilter/nf_conntrack_labels.h>
24 #include <net/netfilter/nf_conntrack_synproxy.h>
25 #include <net/netfilter/nf_conntrack_act_ct.h>
26 #include <net/netfilter/nf_nat.h>
27 
28 #define NF_CT_EXT_PREALLOC	128u /* conntrack events are on by default */
29 
30 atomic_t nf_conntrack_ext_genid __read_mostly = ATOMIC_INIT(1);
31 
32 static const u8 nf_ct_ext_type_len[NF_CT_EXT_NUM] = {
33 	[NF_CT_EXT_HELPER] = sizeof(struct nf_conn_help),
34 #if IS_ENABLED(CONFIG_NF_NAT)
35 	[NF_CT_EXT_NAT] = sizeof(struct nf_conn_nat),
36 #endif
37 	[NF_CT_EXT_SEQADJ] = sizeof(struct nf_conn_seqadj),
38 	[NF_CT_EXT_ACCT] = sizeof(struct nf_conn_acct),
39 #ifdef CONFIG_NF_CONNTRACK_EVENTS
40 	[NF_CT_EXT_ECACHE] = sizeof(struct nf_conntrack_ecache),
41 #endif
42 #ifdef CONFIG_NF_CONNTRACK_TIMESTAMP
43 	[NF_CT_EXT_TSTAMP] = sizeof(struct nf_conn_acct),
44 #endif
45 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
46 	[NF_CT_EXT_TIMEOUT] = sizeof(struct nf_conn_tstamp),
47 #endif
48 #ifdef CONFIG_NF_CONNTRACK_LABELS
49 	[NF_CT_EXT_LABELS] = sizeof(struct nf_conn_labels),
50 #endif
51 #if IS_ENABLED(CONFIG_NETFILTER_SYNPROXY)
52 	[NF_CT_EXT_SYNPROXY] = sizeof(struct nf_conn_synproxy),
53 #endif
54 #if IS_ENABLED(CONFIG_NET_ACT_CT)
55 	[NF_CT_EXT_ACT_CT] = sizeof(struct nf_conn_act_ct_ext),
56 #endif
57 };
58 
total_extension_size(void)59 static __always_inline unsigned int total_extension_size(void)
60 {
61 	/* remember to add new extensions below */
62 	BUILD_BUG_ON(NF_CT_EXT_NUM > 10);
63 
64 	return sizeof(struct nf_ct_ext) +
65 	       sizeof(struct nf_conn_help)
66 #if IS_ENABLED(CONFIG_NF_NAT)
67 		+ sizeof(struct nf_conn_nat)
68 #endif
69 		+ sizeof(struct nf_conn_seqadj)
70 		+ sizeof(struct nf_conn_acct)
71 #ifdef CONFIG_NF_CONNTRACK_EVENTS
72 		+ sizeof(struct nf_conntrack_ecache)
73 #endif
74 #ifdef CONFIG_NF_CONNTRACK_TIMESTAMP
75 		+ sizeof(struct nf_conn_tstamp)
76 #endif
77 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
78 		+ sizeof(struct nf_conn_timeout)
79 #endif
80 #ifdef CONFIG_NF_CONNTRACK_LABELS
81 		+ sizeof(struct nf_conn_labels)
82 #endif
83 #if IS_ENABLED(CONFIG_NETFILTER_SYNPROXY)
84 		+ sizeof(struct nf_conn_synproxy)
85 #endif
86 #if IS_ENABLED(CONFIG_NET_ACT_CT)
87 		+ sizeof(struct nf_conn_act_ct_ext)
88 #endif
89 	;
90 }
91 
nf_ct_ext_add(struct nf_conn * ct,enum nf_ct_ext_id id,gfp_t gfp)92 void *nf_ct_ext_add(struct nf_conn *ct, enum nf_ct_ext_id id, gfp_t gfp)
93 {
94 	unsigned int newlen, newoff, oldlen, alloc;
95 	struct nf_ct_ext *new;
96 
97 	/* Conntrack must not be confirmed to avoid races on reallocation. */
98 	WARN_ON(nf_ct_is_confirmed(ct));
99 
100 	/* struct nf_ct_ext uses u8 to store offsets/size */
101 	BUILD_BUG_ON(total_extension_size() > 255u);
102 
103 	if (ct->ext) {
104 		const struct nf_ct_ext *old = ct->ext;
105 
106 		if (__nf_ct_ext_exist(old, id))
107 			return NULL;
108 		oldlen = old->len;
109 	} else {
110 		oldlen = sizeof(*new);
111 	}
112 
113 	newoff = ALIGN(oldlen, __alignof__(struct nf_ct_ext));
114 	newlen = newoff + nf_ct_ext_type_len[id];
115 
116 	alloc = max(newlen, NF_CT_EXT_PREALLOC);
117 	new = krealloc(ct->ext, alloc, gfp);
118 	if (!new)
119 		return NULL;
120 
121 	if (!ct->ext) {
122 		memset(new->offset, 0, sizeof(new->offset));
123 		new->gen_id = atomic_read(&nf_conntrack_ext_genid);
124 	}
125 
126 	new->offset[id] = newoff;
127 	new->len = newlen;
128 	memset((void *)new + newoff, 0, newlen - newoff);
129 
130 	ct->ext = new;
131 	return (void *)new + newoff;
132 }
133 EXPORT_SYMBOL(nf_ct_ext_add);
134 
135 /* Use nf_ct_ext_find wrapper. This is only useful for unconfirmed entries. */
__nf_ct_ext_find(const struct nf_ct_ext * ext,u8 id)136 void *__nf_ct_ext_find(const struct nf_ct_ext *ext, u8 id)
137 {
138 	unsigned int gen_id = atomic_read(&nf_conntrack_ext_genid);
139 	unsigned int this_id = READ_ONCE(ext->gen_id);
140 
141 	if (!__nf_ct_ext_exist(ext, id))
142 		return NULL;
143 
144 	if (this_id == 0 || ext->gen_id == gen_id)
145 		return (void *)ext + ext->offset[id];
146 
147 	return NULL;
148 }
149 EXPORT_SYMBOL(__nf_ct_ext_find);
150 
nf_ct_ext_bump_genid(void)151 void nf_ct_ext_bump_genid(void)
152 {
153 	unsigned int value = atomic_inc_return(&nf_conntrack_ext_genid);
154 
155 	if (value == UINT_MAX)
156 		atomic_set(&nf_conntrack_ext_genid, 1);
157 
158 	msleep(HZ);
159 }
160