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Linux/crypto/crypto_null.c

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

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