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 s = mpi_read_raw_from_sgl(req->src, req->src_len);
219 if (!s) {
220 ret = -ENOMEM;
221 goto err_free_m;
222 }
223
224 ret = _rsa_verify(pkey, m, s);
225 if (ret)
226 goto err_free_s;
227
228 ret = mpi_write_to_sgl(m, req->dst, req->dst_len, &sign);
229 if (ret)
230 goto err_free_s;
231
232 if (sign < 0)
233 ret = -EBADMSG;
234
235err_free_s:
236 mpi_free(s);
237err_free_m:
238 mpi_free(m);
239 return ret;
240}
241
242static void rsa_free_mpi_key(struct rsa_mpi_key *key)
243{
244 mpi_free(key->d);
245 mpi_free(key->e);
246 mpi_free(key->n);
247 key->d = NULL;
248 key->e = NULL;
249 key->n = NULL;
250}
251
252static int rsa_check_key_length(unsigned int len)
253{
254 switch (len) {
255 case 512:
256 case 1024:
257 case 1536:
258 case 2048:
259 case 3072:
260 case 4096:
261 return 0;
262 }
263
264 return -EINVAL;
265}
266
267static int rsa_set_pub_key(struct crypto_akcipher *tfm, const void *key,
268 unsigned int keylen)
269{
270 struct rsa_mpi_key *mpi_key = akcipher_tfm_ctx(tfm);
271 struct rsa_key raw_key = {0};
272 int ret;
273
274 /* Free the old MPI key if any */
275 rsa_free_mpi_key(mpi_key);
276
277 ret = rsa_parse_pub_key(&raw_key, key, keylen);
278 if (ret)
279 return ret;
280
281 mpi_key->e = mpi_read_raw_data(raw_key.e, raw_key.e_sz);
282 if (!mpi_key->e)
283 goto err;
284
285 mpi_key->n = mpi_read_raw_data(raw_key.n, raw_key.n_sz);
286 if (!mpi_key->n)
287 goto err;
288
289 if (rsa_check_key_length(mpi_get_size(mpi_key->n) << 3)) {
290 rsa_free_mpi_key(mpi_key);
291 return -EINVAL;
292 }
293
294 return 0;
295
296err:
297 rsa_free_mpi_key(mpi_key);
298 return -ENOMEM;
299}
300
301static int rsa_set_priv_key(struct crypto_akcipher *tfm, const void *key,
302 unsigned int keylen)
303{
304 struct rsa_mpi_key *mpi_key = akcipher_tfm_ctx(tfm);
305 struct rsa_key raw_key = {0};
306 int ret;
307
308 /* Free the old MPI key if any */
309 rsa_free_mpi_key(mpi_key);
310
311 ret = rsa_parse_priv_key(&raw_key, key, keylen);
312 if (ret)
313 return ret;
314
315 mpi_key->d = mpi_read_raw_data(raw_key.d, raw_key.d_sz);
316 if (!mpi_key->d)
317 goto err;
318
319 mpi_key->e = mpi_read_raw_data(raw_key.e, raw_key.e_sz);
320 if (!mpi_key->e)
321 goto err;
322
323 mpi_key->n = mpi_read_raw_data(raw_key.n, raw_key.n_sz);
324 if (!mpi_key->n)
325 goto err;
326
327 if (rsa_check_key_length(mpi_get_size(mpi_key->n) << 3)) {
328 rsa_free_mpi_key(mpi_key);
329 return -EINVAL;
330 }
331
332 return 0;
333
334err:
335 rsa_free_mpi_key(mpi_key);
336 return -ENOMEM;
337}
338
339static unsigned int rsa_max_size(struct crypto_akcipher *tfm)
340{
341 struct rsa_mpi_key *pkey = akcipher_tfm_ctx(tfm);
342
343 return mpi_get_size(pkey->n);
344}
345
346static void rsa_exit_tfm(struct crypto_akcipher *tfm)
347{
348 struct rsa_mpi_key *pkey = akcipher_tfm_ctx(tfm);
349
350 rsa_free_mpi_key(pkey);
351}
352
353static struct akcipher_alg rsa = {
354 .encrypt = rsa_enc,
355 .decrypt = rsa_dec,
356 .sign = rsa_sign,
357 .verify = rsa_verify,
358 .set_priv_key = rsa_set_priv_key,
359 .set_pub_key = rsa_set_pub_key,
360 .max_size = rsa_max_size,
361 .exit = rsa_exit_tfm,
362 .base = {
363 .cra_name = "rsa",
364 .cra_driver_name = "rsa-generic",
365 .cra_priority = 100,
366 .cra_module = THIS_MODULE,
367 .cra_ctxsize = sizeof(struct rsa_mpi_key),
368 },
369};
370
371static int rsa_init(void)
372{
373 int err;
374
375 err = crypto_register_akcipher(&rsa);
376 if (err)
377 return err;
378
379 err = crypto_register_template(&rsa_pkcs1pad_tmpl);
380 if (err) {
381 crypto_unregister_akcipher(&rsa);
382 return err;
383 }
384
385 return 0;
386}
387
388static void rsa_exit(void)
389{
390 crypto_unregister_template(&rsa_pkcs1pad_tmpl);
391 crypto_unregister_akcipher(&rsa);
392}
393
394module_init(rsa_init);
395module_exit(rsa_exit);
396MODULE_ALIAS_CRYPTO("rsa");
397MODULE_LICENSE("GPL");
398MODULE_DESCRIPTION("RSA generic algorithm");
399