1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Cryptographic API.
4 *
5 * Null algorithms, aka Much Ado About Nothing.
6 *
7 * These are needed for IPsec, and may be useful in general for
8 * testing & debugging.
9 *
10 * The null cipher is compliant with RFC2410.
11 *
12 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
13 */
14
15 #include <crypto/null.h>
16 #include <crypto/internal/hash.h>
17 #include <crypto/internal/skcipher.h>
18 #include <linux/init.h>
19 #include <linux/module.h>
20 #include <linux/mm.h>
21 #include <linux/string.h>
22
23 static DEFINE_MUTEX(crypto_default_null_skcipher_lock);
24 static struct crypto_sync_skcipher *crypto_default_null_skcipher;
25 static int crypto_default_null_skcipher_refcnt;
26
27 static int null_compress(struct crypto_tfm *tfm, const u8 *src,
28 unsigned int slen, u8 *dst, unsigned int *dlen)
29 {
30 if (slen > *dlen)
31 return -EINVAL;
32 memcpy(dst, src, slen);
33 *dlen = slen;
34 return 0;
35 }
36
37 static int null_init(struct shash_desc *desc)
38 {
39 return 0;
40 }
41
42 static int null_update(struct shash_desc *desc, const u8 *data,
43 unsigned int len)
44 {
45 return 0;
46 }
47
48 static int null_final(struct shash_desc *desc, u8 *out)
49 {
50 return 0;
51 }
52
53 static int null_digest(struct shash_desc *desc, const u8 *data,
54 unsigned int len, u8 *out)
55 {
56 return 0;
57 }
58
59 static int null_hash_setkey(struct crypto_shash *tfm, const u8 *key,
60 unsigned int keylen)
61 { return 0; }
62
63 static int null_skcipher_setkey(struct crypto_skcipher *tfm, const u8 *key,
64 unsigned int keylen)
65 { return 0; }
66
67 static int null_setkey(struct crypto_tfm *tfm, const u8 *key,
68 unsigned int keylen)
69 { return 0; }
70
71 static void null_crypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
72 {
73 memcpy(dst, src, NULL_BLOCK_SIZE);
74 }
75
76 static int null_skcipher_crypt(struct skcipher_request *req)
77 {
78 struct skcipher_walk walk;
79 int err;
80
81 err = skcipher_walk_virt(&walk, req, false);
82
83 while (walk.nbytes) {
84 if (walk.src.virt.addr != walk.dst.virt.addr)
85 memcpy(walk.dst.virt.addr, walk.src.virt.addr,
86 walk.nbytes);
87 err = skcipher_walk_done(&walk, 0);
88 }
89
90 return err;
91 }
92
93 static struct shash_alg digest_null = {
94 .digestsize = NULL_DIGEST_SIZE,
95 .setkey = null_hash_setkey,
96 .init = null_init,
97 .update = null_update,
98 .finup = null_digest,
99 .digest = null_digest,
100 .final = null_final,
101 .base = {
102 .cra_name = "digest_null",
103 .cra_driver_name = "digest_null-generic",
104 .cra_blocksize = NULL_BLOCK_SIZE,
105 .cra_module = THIS_MODULE,
106 }
107 };
108
109 static struct skcipher_alg skcipher_null = {
110 .base.cra_name = "ecb(cipher_null)",
111 .base.cra_driver_name = "ecb-cipher_null",
112 .base.cra_priority = 100,
113 .base.cra_blocksize = NULL_BLOCK_SIZE,
114 .base.cra_ctxsize = 0,
115 .base.cra_module = THIS_MODULE,
116 .min_keysize = NULL_KEY_SIZE,
117 .max_keysize = NULL_KEY_SIZE,
118 .ivsize = NULL_IV_SIZE,
119 .setkey = null_skcipher_setkey,
120 .encrypt = null_skcipher_crypt,
121 .decrypt = null_skcipher_crypt,
122 };
123
124 static struct crypto_alg null_algs[] = { {
125 .cra_name = "cipher_null",
126 .cra_driver_name = "cipher_null-generic",
127 .cra_flags = CRYPTO_ALG_TYPE_CIPHER,
128 .cra_blocksize = NULL_BLOCK_SIZE,
129 .cra_ctxsize = 0,
130 .cra_module = THIS_MODULE,
131 .cra_u = { .cipher = {
132 .cia_min_keysize = NULL_KEY_SIZE,
133 .cia_max_keysize = NULL_KEY_SIZE,
134 .cia_setkey = null_setkey,
135 .cia_encrypt = null_crypt,
136 .cia_decrypt = null_crypt } }
137 }, {
138 .cra_name = "compress_null",
139 .cra_driver_name = "compress_null-generic",
140 .cra_flags = CRYPTO_ALG_TYPE_COMPRESS,
141 .cra_blocksize = NULL_BLOCK_SIZE,
142 .cra_ctxsize = 0,
143 .cra_module = THIS_MODULE,
144 .cra_u = { .compress = {
145 .coa_compress = null_compress,
146 .coa_decompress = null_compress } }
147 } };
148
149 MODULE_ALIAS_CRYPTO("compress_null");
150 MODULE_ALIAS_CRYPTO("digest_null");
151 MODULE_ALIAS_CRYPTO("cipher_null");
152
153 struct crypto_sync_skcipher *crypto_get_default_null_skcipher(void)
154 {
155 struct crypto_sync_skcipher *tfm;
156
157 mutex_lock(&crypto_default_null_skcipher_lock);
158 tfm = crypto_default_null_skcipher;
159
160 if (!tfm) {
161 tfm = crypto_alloc_sync_skcipher("ecb(cipher_null)", 0, 0);
162 if (IS_ERR(tfm))
163 goto unlock;
164
165 crypto_default_null_skcipher = tfm;
166 }
167
168 crypto_default_null_skcipher_refcnt++;
169
170 unlock:
171 mutex_unlock(&crypto_default_null_skcipher_lock);
172
173 return tfm;
174 }
175 EXPORT_SYMBOL_GPL(crypto_get_default_null_skcipher);
176
177 void crypto_put_default_null_skcipher(void)
178 {
179 mutex_lock(&crypto_default_null_skcipher_lock);
180 if (!--crypto_default_null_skcipher_refcnt) {
181 crypto_free_sync_skcipher(crypto_default_null_skcipher);
182 crypto_default_null_skcipher = NULL;
183 }
184 mutex_unlock(&crypto_default_null_skcipher_lock);
185 }
186 EXPORT_SYMBOL_GPL(crypto_put_default_null_skcipher);
187
188 static int __init crypto_null_mod_init(void)
189 {
190 int ret = 0;
191
192 ret = crypto_register_algs(null_algs, ARRAY_SIZE(null_algs));
193 if (ret < 0)
194 goto out;
195
196 ret = crypto_register_shash(&digest_null);
197 if (ret < 0)
198 goto out_unregister_algs;
199
200 ret = crypto_register_skcipher(&skcipher_null);
201 if (ret < 0)
202 goto out_unregister_shash;
203
204 return 0;
205
206 out_unregister_shash:
207 crypto_unregister_shash(&digest_null);
208 out_unregister_algs:
209 crypto_unregister_algs(null_algs, ARRAY_SIZE(null_algs));
210 out:
211 return ret;
212 }
213
214 static void __exit crypto_null_mod_fini(void)
215 {
216 crypto_unregister_algs(null_algs, ARRAY_SIZE(null_algs));
217 crypto_unregister_shash(&digest_null);
218 crypto_unregister_skcipher(&skcipher_null);
219 }
220
221 subsys_initcall(crypto_null_mod_init);
222 module_exit(crypto_null_mod_fini);
223
224 MODULE_LICENSE("GPL");
225 MODULE_DESCRIPTION("Null Cryptographic Algorithms");
226
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