Version:  2.0.40 2.2.26 2.4.37 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10

Linux/crypto/cmac.c

  1 /*
  2  * CMAC: Cipher Block Mode for Authentication
  3  *
  4  * Copyright © 2013 Jussi Kivilinna <jussi.kivilinna@iki.fi>
  5  *
  6  * Based on work by:
  7  *  Copyright © 2013 Tom St Denis <tstdenis@elliptictech.com>
  8  * Based on crypto/xcbc.c:
  9  *  Copyright © 2006 USAGI/WIDE Project,
 10  *   Author: Kazunori Miyazawa <miyazawa@linux-ipv6.org>
 11  *
 12  * This program is free software; you can redistribute it and/or modify
 13  * it under the terms of the GNU General Public License as published by
 14  * the Free Software Foundation; either version 2 of the License, or
 15  * (at your option) any later version.
 16  *
 17  */
 18 
 19 #include <crypto/internal/hash.h>
 20 #include <linux/err.h>
 21 #include <linux/kernel.h>
 22 #include <linux/module.h>
 23 
 24 /*
 25  * +------------------------
 26  * | <parent tfm>
 27  * +------------------------
 28  * | cmac_tfm_ctx
 29  * +------------------------
 30  * | consts (block size * 2)
 31  * +------------------------
 32  */
 33 struct cmac_tfm_ctx {
 34         struct crypto_cipher *child;
 35         u8 ctx[];
 36 };
 37 
 38 /*
 39  * +------------------------
 40  * | <shash desc>
 41  * +------------------------
 42  * | cmac_desc_ctx
 43  * +------------------------
 44  * | odds (block size)
 45  * +------------------------
 46  * | prev (block size)
 47  * +------------------------
 48  */
 49 struct cmac_desc_ctx {
 50         unsigned int len;
 51         u8 ctx[];
 52 };
 53 
 54 static int crypto_cmac_digest_setkey(struct crypto_shash *parent,
 55                                      const u8 *inkey, unsigned int keylen)
 56 {
 57         unsigned long alignmask = crypto_shash_alignmask(parent);
 58         struct cmac_tfm_ctx *ctx = crypto_shash_ctx(parent);
 59         unsigned int bs = crypto_shash_blocksize(parent);
 60         __be64 *consts = PTR_ALIGN((void *)ctx->ctx,
 61                                    (alignmask | (__alignof__(__be64) - 1)) + 1);
 62         u64 _const[2];
 63         int i, err = 0;
 64         u8 msb_mask, gfmask;
 65 
 66         err = crypto_cipher_setkey(ctx->child, inkey, keylen);
 67         if (err)
 68                 return err;
 69 
 70         /* encrypt the zero block */
 71         memset(consts, 0, bs);
 72         crypto_cipher_encrypt_one(ctx->child, (u8 *)consts, (u8 *)consts);
 73 
 74         switch (bs) {
 75         case 16:
 76                 gfmask = 0x87;
 77                 _const[0] = be64_to_cpu(consts[1]);
 78                 _const[1] = be64_to_cpu(consts[0]);
 79 
 80                 /* gf(2^128) multiply zero-ciphertext with u and u^2 */
 81                 for (i = 0; i < 4; i += 2) {
 82                         msb_mask = ((s64)_const[1] >> 63) & gfmask;
 83                         _const[1] = (_const[1] << 1) | (_const[0] >> 63);
 84                         _const[0] = (_const[0] << 1) ^ msb_mask;
 85 
 86                         consts[i + 0] = cpu_to_be64(_const[1]);
 87                         consts[i + 1] = cpu_to_be64(_const[0]);
 88                 }
 89 
 90                 break;
 91         case 8:
 92                 gfmask = 0x1B;
 93                 _const[0] = be64_to_cpu(consts[0]);
 94 
 95                 /* gf(2^64) multiply zero-ciphertext with u and u^2 */
 96                 for (i = 0; i < 2; i++) {
 97                         msb_mask = ((s64)_const[0] >> 63) & gfmask;
 98                         _const[0] = (_const[0] << 1) ^ msb_mask;
 99 
100                         consts[i] = cpu_to_be64(_const[0]);
101                 }
102 
103                 break;
104         }
105 
106         return 0;
107 }
108 
109 static int crypto_cmac_digest_init(struct shash_desc *pdesc)
110 {
111         unsigned long alignmask = crypto_shash_alignmask(pdesc->tfm);
112         struct cmac_desc_ctx *ctx = shash_desc_ctx(pdesc);
113         int bs = crypto_shash_blocksize(pdesc->tfm);
114         u8 *prev = PTR_ALIGN((void *)ctx->ctx, alignmask + 1) + bs;
115 
116         ctx->len = 0;
117         memset(prev, 0, bs);
118 
119         return 0;
120 }
121 
122 static int crypto_cmac_digest_update(struct shash_desc *pdesc, const u8 *p,
123                                      unsigned int len)
124 {
125         struct crypto_shash *parent = pdesc->tfm;
126         unsigned long alignmask = crypto_shash_alignmask(parent);
127         struct cmac_tfm_ctx *tctx = crypto_shash_ctx(parent);
128         struct cmac_desc_ctx *ctx = shash_desc_ctx(pdesc);
129         struct crypto_cipher *tfm = tctx->child;
130         int bs = crypto_shash_blocksize(parent);
131         u8 *odds = PTR_ALIGN((void *)ctx->ctx, alignmask + 1);
132         u8 *prev = odds + bs;
133 
134         /* checking the data can fill the block */
135         if ((ctx->len + len) <= bs) {
136                 memcpy(odds + ctx->len, p, len);
137                 ctx->len += len;
138                 return 0;
139         }
140 
141         /* filling odds with new data and encrypting it */
142         memcpy(odds + ctx->len, p, bs - ctx->len);
143         len -= bs - ctx->len;
144         p += bs - ctx->len;
145 
146         crypto_xor(prev, odds, bs);
147         crypto_cipher_encrypt_one(tfm, prev, prev);
148 
149         /* clearing the length */
150         ctx->len = 0;
151 
152         /* encrypting the rest of data */
153         while (len > bs) {
154                 crypto_xor(prev, p, bs);
155                 crypto_cipher_encrypt_one(tfm, prev, prev);
156                 p += bs;
157                 len -= bs;
158         }
159 
160         /* keeping the surplus of blocksize */
161         if (len) {
162                 memcpy(odds, p, len);
163                 ctx->len = len;
164         }
165 
166         return 0;
167 }
168 
169 static int crypto_cmac_digest_final(struct shash_desc *pdesc, u8 *out)
170 {
171         struct crypto_shash *parent = pdesc->tfm;
172         unsigned long alignmask = crypto_shash_alignmask(parent);
173         struct cmac_tfm_ctx *tctx = crypto_shash_ctx(parent);
174         struct cmac_desc_ctx *ctx = shash_desc_ctx(pdesc);
175         struct crypto_cipher *tfm = tctx->child;
176         int bs = crypto_shash_blocksize(parent);
177         u8 *consts = PTR_ALIGN((void *)tctx->ctx,
178                                (alignmask | (__alignof__(__be64) - 1)) + 1);
179         u8 *odds = PTR_ALIGN((void *)ctx->ctx, alignmask + 1);
180         u8 *prev = odds + bs;
181         unsigned int offset = 0;
182 
183         if (ctx->len != bs) {
184                 unsigned int rlen;
185                 u8 *p = odds + ctx->len;
186 
187                 *p = 0x80;
188                 p++;
189 
190                 rlen = bs - ctx->len - 1;
191                 if (rlen)
192                         memset(p, 0, rlen);
193 
194                 offset += bs;
195         }
196 
197         crypto_xor(prev, odds, bs);
198         crypto_xor(prev, consts + offset, bs);
199 
200         crypto_cipher_encrypt_one(tfm, out, prev);
201 
202         return 0;
203 }
204 
205 static int cmac_init_tfm(struct crypto_tfm *tfm)
206 {
207         struct crypto_cipher *cipher;
208         struct crypto_instance *inst = (void *)tfm->__crt_alg;
209         struct crypto_spawn *spawn = crypto_instance_ctx(inst);
210         struct cmac_tfm_ctx *ctx = crypto_tfm_ctx(tfm);
211 
212         cipher = crypto_spawn_cipher(spawn);
213         if (IS_ERR(cipher))
214                 return PTR_ERR(cipher);
215 
216         ctx->child = cipher;
217 
218         return 0;
219 };
220 
221 static void cmac_exit_tfm(struct crypto_tfm *tfm)
222 {
223         struct cmac_tfm_ctx *ctx = crypto_tfm_ctx(tfm);
224         crypto_free_cipher(ctx->child);
225 }
226 
227 static int cmac_create(struct crypto_template *tmpl, struct rtattr **tb)
228 {
229         struct shash_instance *inst;
230         struct crypto_alg *alg;
231         unsigned long alignmask;
232         int err;
233 
234         err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH);
235         if (err)
236                 return err;
237 
238         alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
239                                   CRYPTO_ALG_TYPE_MASK);
240         if (IS_ERR(alg))
241                 return PTR_ERR(alg);
242 
243         switch (alg->cra_blocksize) {
244         case 16:
245         case 8:
246                 break;
247         default:
248                 err = -EINVAL;
249                 goto out_put_alg;
250         }
251 
252         inst = shash_alloc_instance("cmac", alg);
253         err = PTR_ERR(inst);
254         if (IS_ERR(inst))
255                 goto out_put_alg;
256 
257         err = crypto_init_spawn(shash_instance_ctx(inst), alg,
258                                 shash_crypto_instance(inst),
259                                 CRYPTO_ALG_TYPE_MASK);
260         if (err)
261                 goto out_free_inst;
262 
263         /* We access the data as u32s when xoring. */
264         alignmask = alg->cra_alignmask | (__alignof__(u32) - 1);
265         inst->alg.base.cra_alignmask = alignmask;
266         inst->alg.base.cra_priority = alg->cra_priority;
267         inst->alg.base.cra_blocksize = alg->cra_blocksize;
268 
269         inst->alg.digestsize = alg->cra_blocksize;
270         inst->alg.descsize =
271                 ALIGN(sizeof(struct cmac_desc_ctx), crypto_tfm_ctx_alignment())
272                 + (alignmask & ~(crypto_tfm_ctx_alignment() - 1))
273                 + alg->cra_blocksize * 2;
274 
275         inst->alg.base.cra_ctxsize =
276                 ALIGN(sizeof(struct cmac_tfm_ctx), crypto_tfm_ctx_alignment())
277                 + ((alignmask | (__alignof__(__be64) - 1)) &
278                    ~(crypto_tfm_ctx_alignment() - 1))
279                 + alg->cra_blocksize * 2;
280 
281         inst->alg.base.cra_init = cmac_init_tfm;
282         inst->alg.base.cra_exit = cmac_exit_tfm;
283 
284         inst->alg.init = crypto_cmac_digest_init;
285         inst->alg.update = crypto_cmac_digest_update;
286         inst->alg.final = crypto_cmac_digest_final;
287         inst->alg.setkey = crypto_cmac_digest_setkey;
288 
289         err = shash_register_instance(tmpl, inst);
290         if (err) {
291 out_free_inst:
292                 shash_free_instance(shash_crypto_instance(inst));
293         }
294 
295 out_put_alg:
296         crypto_mod_put(alg);
297         return err;
298 }
299 
300 static struct crypto_template crypto_cmac_tmpl = {
301         .name = "cmac",
302         .create = cmac_create,
303         .free = shash_free_instance,
304         .module = THIS_MODULE,
305 };
306 
307 static int __init crypto_cmac_module_init(void)
308 {
309         return crypto_register_template(&crypto_cmac_tmpl);
310 }
311 
312 static void __exit crypto_cmac_module_exit(void)
313 {
314         crypto_unregister_template(&crypto_cmac_tmpl);
315 }
316 
317 module_init(crypto_cmac_module_init);
318 module_exit(crypto_cmac_module_exit);
319 
320 MODULE_LICENSE("GPL");
321 MODULE_DESCRIPTION("CMAC keyed hash algorithm");
322 MODULE_ALIAS_CRYPTO("cmac");
323 

This page was automatically generated by LXR 0.3.1 (source).  •  Linux is a registered trademark of Linus Torvalds  •  Contact us