1 // SPDX-License-Identifier: GPL-2.0-or-later 1
2 /* RSA asymmetric public-key algorithm [RFC344
3 *
4 * Copyright (c) 2015, Intel Corporation
5 * Authors: Tadeusz Struk <tadeusz.struk@intel
6 */
7
8 #include <linux/fips.h>
9 #include <linux/module.h>
10 #include <linux/mpi.h>
11 #include <crypto/internal/rsa.h>
12 #include <crypto/internal/akcipher.h>
13 #include <crypto/akcipher.h>
14 #include <crypto/algapi.h>
15
16 struct rsa_mpi_key {
17 MPI n;
18 MPI e;
19 MPI d;
20 MPI p;
21 MPI q;
22 MPI dp;
23 MPI dq;
24 MPI qinv;
25 };
26
27 static int rsa_check_payload(MPI x, MPI n)
28 {
29 MPI n1;
30
31 if (mpi_cmp_ui(x, 1) <= 0)
32 return -EINVAL;
33
34 n1 = mpi_alloc(0);
35 if (!n1)
36 return -ENOMEM;
37
38 if (mpi_sub_ui(n1, n, 1) || mpi_cmp(x,
39 mpi_free(n1);
40 return -EINVAL;
41 }
42
43 mpi_free(n1);
44 return 0;
45 }
46
47 /*
48 * RSAEP function [RFC3447 sec 5.1.1]
49 * c = m^e mod n;
50 */
51 static int _rsa_enc(const struct rsa_mpi_key *
52 {
53 /*
54 * Even though (1) in RFC3447 only req
55 * slightly more conservative and requ
56 * with SP 800-56Br2, Section 7.1.1.
57 */
58 if (rsa_check_payload(m, key->n))
59 return -EINVAL;
60
61 /* (2) c = m^e mod n */
62 return mpi_powm(c, m, key->e, key->n);
63 }
64
65 /*
66 * RSADP function [RFC3447 sec 5.1.2]
67 * m_1 = c^dP mod p;
68 * m_2 = c^dQ mod q;
69 * h = (m_1 - m_2) * qInv mod p;
70 * m = m_2 + q * h;
71 */
72 static int _rsa_dec_crt(const struct rsa_mpi_k
73 {
74 MPI m2, m12_or_qh;
75 int ret = -ENOMEM;
76
77 /*
78 * Even though (1) in RFC3447 only req
79 * slightly more conservative and requ
80 * with SP 800-56Br2, Section 7.1.2.
81 */
82 if (rsa_check_payload(c, key->n))
83 return -EINVAL;
84
85 m2 = mpi_alloc(0);
86 m12_or_qh = mpi_alloc(0);
87 if (!m2 || !m12_or_qh)
88 goto err_free_mpi;
89
90 /* (2i) m_1 = c^dP mod p */
91 ret = mpi_powm(m_or_m1_or_h, c, key->d
92 if (ret)
93 goto err_free_mpi;
94
95 /* (2i) m_2 = c^dQ mod q */
96 ret = mpi_powm(m2, c, key->dq, key->q)
97 if (ret)
98 goto err_free_mpi;
99
100 /* (2iii) h = (m_1 - m_2) * qInv mod p
101 ret = mpi_sub(m12_or_qh, m_or_m1_or_h,
102 mpi_mulm(m_or_m1_or_h, m12_or_qh
103
104 /* (2iv) m = m_2 + q * h */
105 ret = ret ?:
106 mpi_mul(m12_or_qh, key->q, m_or_
107 mpi_addm(m_or_m1_or_h, m2, m12_o
108
109 err_free_mpi:
110 mpi_free(m12_or_qh);
111 mpi_free(m2);
112 return ret;
113 }
114
115 static inline struct rsa_mpi_key *rsa_get_key(
116 {
117 return akcipher_tfm_ctx(tfm);
118 }
119
120 static int rsa_enc(struct akcipher_request *re
121 {
122 struct crypto_akcipher *tfm = crypto_a
123 const struct rsa_mpi_key *pkey = rsa_g
124 MPI m, c = mpi_alloc(0);
125 int ret = 0;
126 int sign;
127
128 if (!c)
129 return -ENOMEM;
130
131 if (unlikely(!pkey->n || !pkey->e)) {
132 ret = -EINVAL;
133 goto err_free_c;
134 }
135
136 ret = -ENOMEM;
137 m = mpi_read_raw_from_sgl(req->src, re
138 if (!m)
139 goto err_free_c;
140
141 ret = _rsa_enc(pkey, c, m);
142 if (ret)
143 goto err_free_m;
144
145 ret = mpi_write_to_sgl(c, req->dst, re
146 if (ret)
147 goto err_free_m;
148
149 if (sign < 0)
150 ret = -EBADMSG;
151
152 err_free_m:
153 mpi_free(m);
154 err_free_c:
155 mpi_free(c);
156 return ret;
157 }
158
159 static int rsa_dec(struct akcipher_request *re
160 {
161 struct crypto_akcipher *tfm = crypto_a
162 const struct rsa_mpi_key *pkey = rsa_g
163 MPI c, m = mpi_alloc(0);
164 int ret = 0;
165 int sign;
166
167 if (!m)
168 return -ENOMEM;
169
170 if (unlikely(!pkey->n || !pkey->d)) {
171 ret = -EINVAL;
172 goto err_free_m;
173 }
174
175 ret = -ENOMEM;
176 c = mpi_read_raw_from_sgl(req->src, re
177 if (!c)
178 goto err_free_m;
179
180 ret = _rsa_dec_crt(pkey, m, c);
181 if (ret)
182 goto err_free_c;
183
184 ret = mpi_write_to_sgl(m, req->dst, re
185 if (ret)
186 goto err_free_c;
187
188 if (sign < 0)
189 ret = -EBADMSG;
190 err_free_c:
191 mpi_free(c);
192 err_free_m:
193 mpi_free(m);
194 return ret;
195 }
196
197 static void rsa_free_mpi_key(struct rsa_mpi_ke
198 {
199 mpi_free(key->d);
200 mpi_free(key->e);
201 mpi_free(key->n);
202 mpi_free(key->p);
203 mpi_free(key->q);
204 mpi_free(key->dp);
205 mpi_free(key->dq);
206 mpi_free(key->qinv);
207 key->d = NULL;
208 key->e = NULL;
209 key->n = NULL;
210 key->p = NULL;
211 key->q = NULL;
212 key->dp = NULL;
213 key->dq = NULL;
214 key->qinv = NULL;
215 }
216
217 static int rsa_check_key_length(unsigned int l
218 {
219 switch (len) {
220 case 512:
221 case 1024:
222 case 1536:
223 if (fips_enabled)
224 return -EINVAL;
225 fallthrough;
226 case 2048:
227 case 3072:
228 case 4096:
229 return 0;
230 }
231
232 return -EINVAL;
233 }
234
235 static int rsa_check_exponent_fips(MPI e)
236 {
237 MPI e_max = NULL;
238 int err;
239
240 /* check if odd */
241 if (!mpi_test_bit(e, 0)) {
242 return -EINVAL;
243 }
244
245 /* check if 2^16 < e < 2^256. */
246 if (mpi_cmp_ui(e, 65536) <= 0) {
247 return -EINVAL;
248 }
249
250 e_max = mpi_alloc(0);
251 if (!e_max)
252 return -ENOMEM;
253
254 err = mpi_set_bit(e_max, 256);
255 if (err) {
256 mpi_free(e_max);
257 return err;
258 }
259
260 if (mpi_cmp(e, e_max) >= 0) {
261 mpi_free(e_max);
262 return -EINVAL;
263 }
264
265 mpi_free(e_max);
266 return 0;
267 }
268
269 static int rsa_set_pub_key(struct crypto_akcip
270 unsigned int keylen
271 {
272 struct rsa_mpi_key *mpi_key = akcipher
273 struct rsa_key raw_key = {0};
274 int ret;
275
276 /* Free the old MPI key if any */
277 rsa_free_mpi_key(mpi_key);
278
279 ret = rsa_parse_pub_key(&raw_key, key,
280 if (ret)
281 return ret;
282
283 mpi_key->e = mpi_read_raw_data(raw_key
284 if (!mpi_key->e)
285 goto err;
286
287 mpi_key->n = mpi_read_raw_data(raw_key
288 if (!mpi_key->n)
289 goto err;
290
291 if (rsa_check_key_length(mpi_get_size(
292 rsa_free_mpi_key(mpi_key);
293 return -EINVAL;
294 }
295
296 if (fips_enabled && rsa_check_exponent
297 rsa_free_mpi_key(mpi_key);
298 return -EINVAL;
299 }
300
301 return 0;
302
303 err:
304 rsa_free_mpi_key(mpi_key);
305 return -ENOMEM;
306 }
307
308 static int rsa_set_priv_key(struct crypto_akci
309 unsigned int keyle
310 {
311 struct rsa_mpi_key *mpi_key = akcipher
312 struct rsa_key raw_key = {0};
313 int ret;
314
315 /* Free the old MPI key if any */
316 rsa_free_mpi_key(mpi_key);
317
318 ret = rsa_parse_priv_key(&raw_key, key
319 if (ret)
320 return ret;
321
322 mpi_key->d = mpi_read_raw_data(raw_key
323 if (!mpi_key->d)
324 goto err;
325
326 mpi_key->e = mpi_read_raw_data(raw_key
327 if (!mpi_key->e)
328 goto err;
329
330 mpi_key->n = mpi_read_raw_data(raw_key
331 if (!mpi_key->n)
332 goto err;
333
334 mpi_key->p = mpi_read_raw_data(raw_key
335 if (!mpi_key->p)
336 goto err;
337
338 mpi_key->q = mpi_read_raw_data(raw_key
339 if (!mpi_key->q)
340 goto err;
341
342 mpi_key->dp = mpi_read_raw_data(raw_ke
343 if (!mpi_key->dp)
344 goto err;
345
346 mpi_key->dq = mpi_read_raw_data(raw_ke
347 if (!mpi_key->dq)
348 goto err;
349
350 mpi_key->qinv = mpi_read_raw_data(raw_
351 if (!mpi_key->qinv)
352 goto err;
353
354 if (rsa_check_key_length(mpi_get_size(
355 rsa_free_mpi_key(mpi_key);
356 return -EINVAL;
357 }
358
359 if (fips_enabled && rsa_check_exponent
360 rsa_free_mpi_key(mpi_key);
361 return -EINVAL;
362 }
363
364 return 0;
365
366 err:
367 rsa_free_mpi_key(mpi_key);
368 return -ENOMEM;
369 }
370
371 static unsigned int rsa_max_size(struct crypto
372 {
373 struct rsa_mpi_key *pkey = akcipher_tf
374
375 return mpi_get_size(pkey->n);
376 }
377
378 static void rsa_exit_tfm(struct crypto_akciphe
379 {
380 struct rsa_mpi_key *pkey = akcipher_tf
381
382 rsa_free_mpi_key(pkey);
383 }
384
385 static struct akcipher_alg rsa = {
386 .encrypt = rsa_enc,
387 .decrypt = rsa_dec,
388 .set_priv_key = rsa_set_priv_key,
389 .set_pub_key = rsa_set_pub_key,
390 .max_size = rsa_max_size,
391 .exit = rsa_exit_tfm,
392 .base = {
393 .cra_name = "rsa",
394 .cra_driver_name = "rsa-generi
395 .cra_priority = 100,
396 .cra_module = THIS_MODULE,
397 .cra_ctxsize = sizeof(struct r
398 },
399 };
400
401 static int __init rsa_init(void)
402 {
403 int err;
404
405 err = crypto_register_akcipher(&rsa);
406 if (err)
407 return err;
408
409 err = crypto_register_template(&rsa_pk
410 if (err) {
411 crypto_unregister_akcipher(&rs
412 return err;
413 }
414
415 return 0;
416 }
417
418 static void __exit rsa_exit(void)
419 {
420 crypto_unregister_template(&rsa_pkcs1p
421 crypto_unregister_akcipher(&rsa);
422 }
423
424 subsys_initcall(rsa_init);
425 module_exit(rsa_exit);
426 MODULE_ALIAS_CRYPTO("rsa");
427 MODULE_LICENSE("GPL");
428 MODULE_DESCRIPTION("RSA generic algorithm");
429
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