1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * CTR: Counter mode
4 *
5 * (C) Copyright IBM Corp. 2007 - Joy Latten <latten@us.ibm.com>
6 */
7
8 #include <crypto/algapi.h>
9 #include <crypto/ctr.h>
10 #include <crypto/internal/skcipher.h>
11 #include <linux/err.h>
12 #include <linux/init.h>
13 #include <linux/kernel.h>
14 #include <linux/module.h>
15 #include <linux/slab.h>
16
17 struct crypto_rfc3686_ctx {
18 struct crypto_skcipher *child;
19 u8 nonce[CTR_RFC3686_NONCE_SIZE];
20 };
21
22 struct crypto_rfc3686_req_ctx {
23 u8 iv[CTR_RFC3686_BLOCK_SIZE];
24 struct skcipher_request subreq CRYPTO_MINALIGN_ATTR;
25 };
26
crypto_ctr_crypt_final(struct skcipher_walk * walk,struct crypto_cipher * tfm)27 static void crypto_ctr_crypt_final(struct skcipher_walk *walk,
28 struct crypto_cipher *tfm)
29 {
30 unsigned int bsize = crypto_cipher_blocksize(tfm);
31 unsigned long alignmask = crypto_cipher_alignmask(tfm);
32 u8 *ctrblk = walk->iv;
33 u8 tmp[MAX_CIPHER_BLOCKSIZE + MAX_CIPHER_ALIGNMASK];
34 u8 *keystream = PTR_ALIGN(tmp + 0, alignmask + 1);
35 u8 *src = walk->src.virt.addr;
36 u8 *dst = walk->dst.virt.addr;
37 unsigned int nbytes = walk->nbytes;
38
39 crypto_cipher_encrypt_one(tfm, keystream, ctrblk);
40 crypto_xor_cpy(dst, keystream, src, nbytes);
41
42 crypto_inc(ctrblk, bsize);
43 }
44
crypto_ctr_crypt_segment(struct skcipher_walk * walk,struct crypto_cipher * tfm)45 static int crypto_ctr_crypt_segment(struct skcipher_walk *walk,
46 struct crypto_cipher *tfm)
47 {
48 void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
49 crypto_cipher_alg(tfm)->cia_encrypt;
50 unsigned int bsize = crypto_cipher_blocksize(tfm);
51 u8 *ctrblk = walk->iv;
52 u8 *src = walk->src.virt.addr;
53 u8 *dst = walk->dst.virt.addr;
54 unsigned int nbytes = walk->nbytes;
55
56 do {
57 /* create keystream */
58 fn(crypto_cipher_tfm(tfm), dst, ctrblk);
59 crypto_xor(dst, src, bsize);
60
61 /* increment counter in counterblock */
62 crypto_inc(ctrblk, bsize);
63
64 src += bsize;
65 dst += bsize;
66 } while ((nbytes -= bsize) >= bsize);
67
68 return nbytes;
69 }
70
crypto_ctr_crypt_inplace(struct skcipher_walk * walk,struct crypto_cipher * tfm)71 static int crypto_ctr_crypt_inplace(struct skcipher_walk *walk,
72 struct crypto_cipher *tfm)
73 {
74 void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
75 crypto_cipher_alg(tfm)->cia_encrypt;
76 unsigned int bsize = crypto_cipher_blocksize(tfm);
77 unsigned long alignmask = crypto_cipher_alignmask(tfm);
78 unsigned int nbytes = walk->nbytes;
79 u8 *ctrblk = walk->iv;
80 u8 *src = walk->src.virt.addr;
81 u8 tmp[MAX_CIPHER_BLOCKSIZE + MAX_CIPHER_ALIGNMASK];
82 u8 *keystream = PTR_ALIGN(tmp + 0, alignmask + 1);
83
84 do {
85 /* create keystream */
86 fn(crypto_cipher_tfm(tfm), keystream, ctrblk);
87 crypto_xor(src, keystream, bsize);
88
89 /* increment counter in counterblock */
90 crypto_inc(ctrblk, bsize);
91
92 src += bsize;
93 } while ((nbytes -= bsize) >= bsize);
94
95 return nbytes;
96 }
97
crypto_ctr_crypt(struct skcipher_request * req)98 static int crypto_ctr_crypt(struct skcipher_request *req)
99 {
100 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
101 struct crypto_cipher *cipher = skcipher_cipher_simple(tfm);
102 const unsigned int bsize = crypto_cipher_blocksize(cipher);
103 struct skcipher_walk walk;
104 unsigned int nbytes;
105 int err;
106
107 err = skcipher_walk_virt(&walk, req, false);
108
109 while (walk.nbytes >= bsize) {
110 if (walk.src.virt.addr == walk.dst.virt.addr)
111 nbytes = crypto_ctr_crypt_inplace(&walk, cipher);
112 else
113 nbytes = crypto_ctr_crypt_segment(&walk, cipher);
114
115 err = skcipher_walk_done(&walk, nbytes);
116 }
117
118 if (walk.nbytes) {
119 crypto_ctr_crypt_final(&walk, cipher);
120 err = skcipher_walk_done(&walk, 0);
121 }
122
123 return err;
124 }
125
crypto_ctr_create(struct crypto_template * tmpl,struct rtattr ** tb)126 static int crypto_ctr_create(struct crypto_template *tmpl, struct rtattr **tb)
127 {
128 struct skcipher_instance *inst;
129 struct crypto_alg *alg;
130 int err;
131
132 inst = skcipher_alloc_instance_simple(tmpl, tb, &alg);
133 if (IS_ERR(inst))
134 return PTR_ERR(inst);
135
136 /* Block size must be >= 4 bytes. */
137 err = -EINVAL;
138 if (alg->cra_blocksize < 4)
139 goto out_free_inst;
140
141 /* If this is false we'd fail the alignment of crypto_inc. */
142 if (alg->cra_blocksize % 4)
143 goto out_free_inst;
144
145 /* CTR mode is a stream cipher. */
146 inst->alg.base.cra_blocksize = 1;
147
148 /*
149 * To simplify the implementation, configure the skcipher walk to only
150 * give a partial block at the very end, never earlier.
151 */
152 inst->alg.chunksize = alg->cra_blocksize;
153
154 inst->alg.encrypt = crypto_ctr_crypt;
155 inst->alg.decrypt = crypto_ctr_crypt;
156
157 err = skcipher_register_instance(tmpl, inst);
158 if (err)
159 goto out_free_inst;
160 goto out_put_alg;
161
162 out_free_inst:
163 inst->free(inst);
164 out_put_alg:
165 crypto_mod_put(alg);
166 return err;
167 }
168
crypto_rfc3686_setkey(struct crypto_skcipher * parent,const u8 * key,unsigned int keylen)169 static int crypto_rfc3686_setkey(struct crypto_skcipher *parent,
170 const u8 *key, unsigned int keylen)
171 {
172 struct crypto_rfc3686_ctx *ctx = crypto_skcipher_ctx(parent);
173 struct crypto_skcipher *child = ctx->child;
174 int err;
175
176 /* the nonce is stored in bytes at end of key */
177 if (keylen < CTR_RFC3686_NONCE_SIZE)
178 return -EINVAL;
179
180 memcpy(ctx->nonce, key + (keylen - CTR_RFC3686_NONCE_SIZE),
181 CTR_RFC3686_NONCE_SIZE);
182
183 keylen -= CTR_RFC3686_NONCE_SIZE;
184
185 crypto_skcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
186 crypto_skcipher_set_flags(child, crypto_skcipher_get_flags(parent) &
187 CRYPTO_TFM_REQ_MASK);
188 err = crypto_skcipher_setkey(child, key, keylen);
189 crypto_skcipher_set_flags(parent, crypto_skcipher_get_flags(child) &
190 CRYPTO_TFM_RES_MASK);
191
192 return err;
193 }
194
crypto_rfc3686_crypt(struct skcipher_request * req)195 static int crypto_rfc3686_crypt(struct skcipher_request *req)
196 {
197 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
198 struct crypto_rfc3686_ctx *ctx = crypto_skcipher_ctx(tfm);
199 struct crypto_skcipher *child = ctx->child;
200 unsigned long align = crypto_skcipher_alignmask(tfm);
201 struct crypto_rfc3686_req_ctx *rctx =
202 (void *)PTR_ALIGN((u8 *)skcipher_request_ctx(req), align + 1);
203 struct skcipher_request *subreq = &rctx->subreq;
204 u8 *iv = rctx->iv;
205
206 /* set up counter block */
207 memcpy(iv, ctx->nonce, CTR_RFC3686_NONCE_SIZE);
208 memcpy(iv + CTR_RFC3686_NONCE_SIZE, req->iv, CTR_RFC3686_IV_SIZE);
209
210 /* initialize counter portion of counter block */
211 *(__be32 *)(iv + CTR_RFC3686_NONCE_SIZE + CTR_RFC3686_IV_SIZE) =
212 cpu_to_be32(1);
213
214 skcipher_request_set_tfm(subreq, child);
215 skcipher_request_set_callback(subreq, req->base.flags,
216 req->base.complete, req->base.data);
217 skcipher_request_set_crypt(subreq, req->src, req->dst,
218 req->cryptlen, iv);
219
220 return crypto_skcipher_encrypt(subreq);
221 }
222
crypto_rfc3686_init_tfm(struct crypto_skcipher * tfm)223 static int crypto_rfc3686_init_tfm(struct crypto_skcipher *tfm)
224 {
225 struct skcipher_instance *inst = skcipher_alg_instance(tfm);
226 struct crypto_skcipher_spawn *spawn = skcipher_instance_ctx(inst);
227 struct crypto_rfc3686_ctx *ctx = crypto_skcipher_ctx(tfm);
228 struct crypto_skcipher *cipher;
229 unsigned long align;
230 unsigned int reqsize;
231
232 cipher = crypto_spawn_skcipher(spawn);
233 if (IS_ERR(cipher))
234 return PTR_ERR(cipher);
235
236 ctx->child = cipher;
237
238 align = crypto_skcipher_alignmask(tfm);
239 align &= ~(crypto_tfm_ctx_alignment() - 1);
240 reqsize = align + sizeof(struct crypto_rfc3686_req_ctx) +
241 crypto_skcipher_reqsize(cipher);
242 crypto_skcipher_set_reqsize(tfm, reqsize);
243
244 return 0;
245 }
246
crypto_rfc3686_exit_tfm(struct crypto_skcipher * tfm)247 static void crypto_rfc3686_exit_tfm(struct crypto_skcipher *tfm)
248 {
249 struct crypto_rfc3686_ctx *ctx = crypto_skcipher_ctx(tfm);
250
251 crypto_free_skcipher(ctx->child);
252 }
253
crypto_rfc3686_free(struct skcipher_instance * inst)254 static void crypto_rfc3686_free(struct skcipher_instance *inst)
255 {
256 struct crypto_skcipher_spawn *spawn = skcipher_instance_ctx(inst);
257
258 crypto_drop_skcipher(spawn);
259 kfree(inst);
260 }
261
crypto_rfc3686_create(struct crypto_template * tmpl,struct rtattr ** tb)262 static int crypto_rfc3686_create(struct crypto_template *tmpl,
263 struct rtattr **tb)
264 {
265 struct crypto_attr_type *algt;
266 struct skcipher_instance *inst;
267 struct skcipher_alg *alg;
268 struct crypto_skcipher_spawn *spawn;
269 const char *cipher_name;
270 u32 mask;
271
272 int err;
273
274 algt = crypto_get_attr_type(tb);
275 if (IS_ERR(algt))
276 return PTR_ERR(algt);
277
278 if ((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask)
279 return -EINVAL;
280
281 cipher_name = crypto_attr_alg_name(tb[1]);
282 if (IS_ERR(cipher_name))
283 return PTR_ERR(cipher_name);
284
285 inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
286 if (!inst)
287 return -ENOMEM;
288
289 mask = crypto_requires_sync(algt->type, algt->mask) |
290 crypto_requires_off(algt->type, algt->mask,
291 CRYPTO_ALG_NEED_FALLBACK);
292
293 spawn = skcipher_instance_ctx(inst);
294
295 crypto_set_skcipher_spawn(spawn, skcipher_crypto_instance(inst));
296 err = crypto_grab_skcipher(spawn, cipher_name, 0, mask);
297 if (err)
298 goto err_free_inst;
299
300 alg = crypto_spawn_skcipher_alg(spawn);
301
302 /* We only support 16-byte blocks. */
303 err = -EINVAL;
304 if (crypto_skcipher_alg_ivsize(alg) != CTR_RFC3686_BLOCK_SIZE)
305 goto err_drop_spawn;
306
307 /* Not a stream cipher? */
308 if (alg->base.cra_blocksize != 1)
309 goto err_drop_spawn;
310
311 err = -ENAMETOOLONG;
312 if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
313 "rfc3686(%s)", alg->base.cra_name) >= CRYPTO_MAX_ALG_NAME)
314 goto err_drop_spawn;
315 if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
316 "rfc3686(%s)", alg->base.cra_driver_name) >=
317 CRYPTO_MAX_ALG_NAME)
318 goto err_drop_spawn;
319
320 inst->alg.base.cra_priority = alg->base.cra_priority;
321 inst->alg.base.cra_blocksize = 1;
322 inst->alg.base.cra_alignmask = alg->base.cra_alignmask;
323
324 inst->alg.base.cra_flags = alg->base.cra_flags & CRYPTO_ALG_ASYNC;
325
326 inst->alg.ivsize = CTR_RFC3686_IV_SIZE;
327 inst->alg.chunksize = crypto_skcipher_alg_chunksize(alg);
328 inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg) +
329 CTR_RFC3686_NONCE_SIZE;
330 inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg) +
331 CTR_RFC3686_NONCE_SIZE;
332
333 inst->alg.setkey = crypto_rfc3686_setkey;
334 inst->alg.encrypt = crypto_rfc3686_crypt;
335 inst->alg.decrypt = crypto_rfc3686_crypt;
336
337 inst->alg.base.cra_ctxsize = sizeof(struct crypto_rfc3686_ctx);
338
339 inst->alg.init = crypto_rfc3686_init_tfm;
340 inst->alg.exit = crypto_rfc3686_exit_tfm;
341
342 inst->free = crypto_rfc3686_free;
343
344 err = skcipher_register_instance(tmpl, inst);
345 if (err)
346 goto err_drop_spawn;
347
348 out:
349 return err;
350
351 err_drop_spawn:
352 crypto_drop_skcipher(spawn);
353 err_free_inst:
354 kfree(inst);
355 goto out;
356 }
357
358 static struct crypto_template crypto_ctr_tmpls[] = {
359 {
360 .name = "ctr",
361 .create = crypto_ctr_create,
362 .module = THIS_MODULE,
363 }, {
364 .name = "rfc3686",
365 .create = crypto_rfc3686_create,
366 .module = THIS_MODULE,
367 },
368 };
369
crypto_ctr_module_init(void)370 static int __init crypto_ctr_module_init(void)
371 {
372 return crypto_register_templates(crypto_ctr_tmpls,
373 ARRAY_SIZE(crypto_ctr_tmpls));
374 }
375
crypto_ctr_module_exit(void)376 static void __exit crypto_ctr_module_exit(void)
377 {
378 crypto_unregister_templates(crypto_ctr_tmpls,
379 ARRAY_SIZE(crypto_ctr_tmpls));
380 }
381
382 subsys_initcall(crypto_ctr_module_init);
383 module_exit(crypto_ctr_module_exit);
384
385 MODULE_LICENSE("GPL");
386 MODULE_DESCRIPTION("CTR block cipher mode of operation");
387 MODULE_ALIAS_CRYPTO("rfc3686");
388 MODULE_ALIAS_CRYPTO("ctr");
389