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1/* RSA asymmetric public-key algorithm [RFC3447]
2 *
3 * Copyright (c) 2015, Intel Corporation
4 * Authors: Tadeusz Struk <tadeusz.struk@intel.com>
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public Licence
8 * as published by the Free Software Foundation; either version
9 * 2 of the Licence, or (at your option) any later version.
10 */
11
12#include <linux/module.h>
13#include <linux/mpi.h>
14#include <crypto/internal/rsa.h>
15#include <crypto/internal/akcipher.h>
16#include <crypto/akcipher.h>
17#include <crypto/algapi.h>
18
19struct rsa_mpi_key {
20 MPI n;
21 MPI e;
22 MPI d;
23};
24
25/*
26 * RSAEP function [RFC3447 sec 5.1.1]
27 * c = m^e mod n;
28 */
29static int _rsa_enc(const struct rsa_mpi_key *key, MPI c, MPI m)
30{
31 /* (1) Validate 0 <= m < n */
32 if (mpi_cmp_ui(m, 0) < 0 || mpi_cmp(m, key->n) >= 0)
33 return -EINVAL;
34
35 /* (2) c = m^e mod n */
36 return mpi_powm(c, m, key->e, key->n);
37}
38
39/*
40 * RSADP function [RFC3447 sec 5.1.2]
41 * m = c^d mod n;
42 */
43static int _rsa_dec(const struct rsa_mpi_key *key, MPI m, MPI c)
44{
45 /* (1) Validate 0 <= c < n */
46 if (mpi_cmp_ui(c, 0) < 0 || mpi_cmp(c, key->n) >= 0)
47 return -EINVAL;
48
49 /* (2) m = c^d mod n */
50 return mpi_powm(m, c, key->d, key->n);
51}
52
53/*
54 * RSASP1 function [RFC3447 sec 5.2.1]
55 * s = m^d mod n
56 */
57static int _rsa_sign(const struct rsa_mpi_key *key, MPI s, MPI m)
58{
59 /* (1) Validate 0 <= m < n */
60 if (mpi_cmp_ui(m, 0) < 0 || mpi_cmp(m, key->n) >= 0)
61 return -EINVAL;
62
63 /* (2) s = m^d mod n */
64 return mpi_powm(s, m, key->d, key->n);
65}
66
67/*
68 * RSAVP1 function [RFC3447 sec 5.2.2]
69 * m = s^e mod n;
70 */
71static int _rsa_verify(const struct rsa_mpi_key *key, MPI m, MPI s)
72{
73 /* (1) Validate 0 <= s < n */
74 if (mpi_cmp_ui(s, 0) < 0 || mpi_cmp(s, key->n) >= 0)
75 return -EINVAL;
76
77 /* (2) m = s^e mod n */
78 return mpi_powm(m, s, key->e, key->n);
79}
80
81static inline struct rsa_mpi_key *rsa_get_key(struct crypto_akcipher *tfm)
82{
83 return akcipher_tfm_ctx(tfm);
84}
85
86static int rsa_enc(struct akcipher_request *req)
87{
88 struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
89 const struct rsa_mpi_key *pkey = rsa_get_key(tfm);
90 MPI m, c = mpi_alloc(0);
91 int ret = 0;
92 int sign;
93
94 if (!c)
95 return -ENOMEM;
96
97 if (unlikely(!pkey->n || !pkey->e)) {
98 ret = -EINVAL;
99 goto err_free_c;
100 }
101
102 ret = -ENOMEM;
103 m = mpi_read_raw_from_sgl(req->src, req->src_len);
104 if (!m)
105 goto err_free_c;
106
107 ret = _rsa_enc(pkey, c, m);
108 if (ret)
109 goto err_free_m;
110
111 ret = mpi_write_to_sgl(c, req->dst, req->dst_len, &sign);
112 if (ret)
113 goto err_free_m;
114
115 if (sign < 0)
116 ret = -EBADMSG;
117
118err_free_m:
119 mpi_free(m);
120err_free_c:
121 mpi_free(c);
122 return ret;
123}
124
125static int rsa_dec(struct akcipher_request *req)
126{
127 struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
128 const struct rsa_mpi_key *pkey = rsa_get_key(tfm);
129 MPI c, m = mpi_alloc(0);
130 int ret = 0;
131 int sign;
132
133 if (!m)
134 return -ENOMEM;
135
136 if (unlikely(!pkey->n || !pkey->d)) {
137 ret = -EINVAL;
138 goto err_free_m;
139 }
140
141 ret = -ENOMEM;
142 c = mpi_read_raw_from_sgl(req->src, req->src_len);
143 if (!c)
144 goto err_free_m;
145
146 ret = _rsa_dec(pkey, m, c);
147 if (ret)
148 goto err_free_c;
149
150 ret = mpi_write_to_sgl(m, req->dst, req->dst_len, &sign);
151 if (ret)
152 goto err_free_c;
153
154 if (sign < 0)
155 ret = -EBADMSG;
156err_free_c:
157 mpi_free(c);
158err_free_m:
159 mpi_free(m);
160 return ret;
161}
162
163static int rsa_sign(struct akcipher_request *req)
164{
165 struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
166 const struct rsa_mpi_key *pkey = rsa_get_key(tfm);
167 MPI m, s = mpi_alloc(0);
168 int ret = 0;
169 int sign;
170
171 if (!s)
172 return -ENOMEM;
173
174 if (unlikely(!pkey->n || !pkey->d)) {
175 ret = -EINVAL;
176 goto err_free_s;
177 }
178
179 ret = -ENOMEM;
180 m = mpi_read_raw_from_sgl(req->src, req->src_len);
181 if (!m)
182 goto err_free_s;
183
184 ret = _rsa_sign(pkey, s, m);
185 if (ret)
186 goto err_free_m;
187
188 ret = mpi_write_to_sgl(s, req->dst, req->dst_len, &sign);
189 if (ret)
190 goto err_free_m;
191
192 if (sign < 0)
193 ret = -EBADMSG;
194
195err_free_m:
196 mpi_free(m);
197err_free_s:
198 mpi_free(s);
199 return ret;
200}
201
202static int rsa_verify(struct akcipher_request *req)
203{
204 struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
205 const struct rsa_mpi_key *pkey = rsa_get_key(tfm);
206 MPI s, m = mpi_alloc(0);
207 int ret = 0;
208 int sign;
209
210 if (!m)
211 return -ENOMEM;
212
213 if (unlikely(!pkey->n || !pkey->e)) {
214 ret = -EINVAL;
215 goto err_free_m;
216 }
217
218 ret = -ENOMEM;
219 s = mpi_read_raw_from_sgl(req->src, req->src_len);
220 if (!s) {
221 ret = -ENOMEM;
222 goto err_free_m;
223 }
224
225 ret = _rsa_verify(pkey, m, s);
226 if (ret)
227 goto err_free_s;
228
229 ret = mpi_write_to_sgl(m, req->dst, req->dst_len, &sign);
230 if (ret)
231 goto err_free_s;
232
233 if (sign < 0)
234 ret = -EBADMSG;
235
236err_free_s:
237 mpi_free(s);
238err_free_m:
239 mpi_free(m);
240 return ret;
241}
242
243static void rsa_free_mpi_key(struct rsa_mpi_key *key)
244{
245 mpi_free(key->d);
246 mpi_free(key->e);
247 mpi_free(key->n);
248 key->d = NULL;
249 key->e = NULL;
250 key->n = NULL;
251}
252
253static int rsa_check_key_length(unsigned int len)
254{
255 switch (len) {
256 case 512:
257 case 1024:
258 case 1536:
259 case 2048:
260 case 3072:
261 case 4096:
262 return 0;
263 }
264
265 return -EINVAL;
266}
267
268static int rsa_set_pub_key(struct crypto_akcipher *tfm, const void *key,
269 unsigned int keylen)
270{
271 struct rsa_mpi_key *mpi_key = akcipher_tfm_ctx(tfm);
272 struct rsa_key raw_key = {0};
273 int ret;
274
275 /* Free the old MPI key if any */
276 rsa_free_mpi_key(mpi_key);
277
278 ret = rsa_parse_pub_key(&raw_key, key, keylen);
279 if (ret)
280 return ret;
281
282 mpi_key->e = mpi_read_raw_data(raw_key.e, raw_key.e_sz);
283 if (!mpi_key->e)
284 goto err;
285
286 mpi_key->n = mpi_read_raw_data(raw_key.n, raw_key.n_sz);
287 if (!mpi_key->n)
288 goto err;
289
290 if (rsa_check_key_length(mpi_get_size(mpi_key->n) << 3)) {
291 rsa_free_mpi_key(mpi_key);
292 return -EINVAL;
293 }
294
295 return 0;
296
297err:
298 rsa_free_mpi_key(mpi_key);
299 return -ENOMEM;
300}
301
302static int rsa_set_priv_key(struct crypto_akcipher *tfm, const void *key,
303 unsigned int keylen)
304{
305 struct rsa_mpi_key *mpi_key = akcipher_tfm_ctx(tfm);
306 struct rsa_key raw_key = {0};
307 int ret;
308
309 /* Free the old MPI key if any */
310 rsa_free_mpi_key(mpi_key);
311
312 ret = rsa_parse_priv_key(&raw_key, key, keylen);
313 if (ret)
314 return ret;
315
316 mpi_key->d = mpi_read_raw_data(raw_key.d, raw_key.d_sz);
317 if (!mpi_key->d)
318 goto err;
319
320 mpi_key->e = mpi_read_raw_data(raw_key.e, raw_key.e_sz);
321 if (!mpi_key->e)
322 goto err;
323
324 mpi_key->n = mpi_read_raw_data(raw_key.n, raw_key.n_sz);
325 if (!mpi_key->n)
326 goto err;
327
328 if (rsa_check_key_length(mpi_get_size(mpi_key->n) << 3)) {
329 rsa_free_mpi_key(mpi_key);
330 return -EINVAL;
331 }
332
333 return 0;
334
335err:
336 rsa_free_mpi_key(mpi_key);
337 return -ENOMEM;
338}
339
340static unsigned int rsa_max_size(struct crypto_akcipher *tfm)
341{
342 struct rsa_mpi_key *pkey = akcipher_tfm_ctx(tfm);
343
344 return mpi_get_size(pkey->n);
345}
346
347static void rsa_exit_tfm(struct crypto_akcipher *tfm)
348{
349 struct rsa_mpi_key *pkey = akcipher_tfm_ctx(tfm);
350
351 rsa_free_mpi_key(pkey);
352}
353
354static struct akcipher_alg rsa = {
355 .encrypt = rsa_enc,
356 .decrypt = rsa_dec,
357 .sign = rsa_sign,
358 .verify = rsa_verify,
359 .set_priv_key = rsa_set_priv_key,
360 .set_pub_key = rsa_set_pub_key,
361 .max_size = rsa_max_size,
362 .exit = rsa_exit_tfm,
363 .base = {
364 .cra_name = "rsa",
365 .cra_driver_name = "rsa-generic",
366 .cra_priority = 100,
367 .cra_module = THIS_MODULE,
368 .cra_ctxsize = sizeof(struct rsa_mpi_key),
369 },
370};
371
372static int rsa_init(void)
373{
374 int err;
375
376 err = crypto_register_akcipher(&rsa);
377 if (err)
378 return err;
379
380 err = crypto_register_template(&rsa_pkcs1pad_tmpl);
381 if (err) {
382 crypto_unregister_akcipher(&rsa);
383 return err;
384 }
385
386 return 0;
387}
388
389static void rsa_exit(void)
390{
391 crypto_unregister_template(&rsa_pkcs1pad_tmpl);
392 crypto_unregister_akcipher(&rsa);
393}
394
395module_init(rsa_init);
396module_exit(rsa_exit);
397MODULE_ALIAS_CRYPTO("rsa");
398MODULE_LICENSE("GPL");
399MODULE_DESCRIPTION("RSA generic algorithm");