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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 <crypto/internal/rsa.h>
14 #include <crypto/internal/akcipher.h>
15 #include <crypto/akcipher.h>
16 #include <crypto/algapi.h>
17
18 /*
19 * RSAEP function [RFC3447 sec 5.1.1]
20 * c = m^e mod n;
21 */
22 static int _rsa_enc(const struct rsa_key *key, MPI c, MPI m)
23 {
24 /* (1) Validate 0 <= m < n */
25 if (mpi_cmp_ui(m, 0) < 0 || mpi_cmp(m, key->n) >= 0)
26 return -EINVAL;
27
28 /* (2) c = m^e mod n */
29 return mpi_powm(c, m, key->e, key->n);
30 }
31
32 /*
33 * RSADP function [RFC3447 sec 5.1.2]
34 * m = c^d mod n;
35 */
36 static int _rsa_dec(const struct rsa_key *key, MPI m, MPI c)
37 {
38 /* (1) Validate 0 <= c < n */
39 if (mpi_cmp_ui(c, 0) < 0 || mpi_cmp(c, key->n) >= 0)
40 return -EINVAL;
41
42 /* (2) m = c^d mod n */
43 return mpi_powm(m, c, key->d, key->n);
44 }
45
46 /*
47 * RSASP1 function [RFC3447 sec 5.2.1]
48 * s = m^d mod n
49 */
50 static int _rsa_sign(const struct rsa_key *key, MPI s, MPI m)
51 {
52 /* (1) Validate 0 <= m < n */
53 if (mpi_cmp_ui(m, 0) < 0 || mpi_cmp(m, key->n) >= 0)
54 return -EINVAL;
55
56 /* (2) s = m^d mod n */
57 return mpi_powm(s, m, key->d, key->n);
58 }
59
60 /*
61 * RSAVP1 function [RFC3447 sec 5.2.2]
62 * m = s^e mod n;
63 */
64 static int _rsa_verify(const struct rsa_key *key, MPI m, MPI s)
65 {
66 /* (1) Validate 0 <= s < n */
67 if (mpi_cmp_ui(s, 0) < 0 || mpi_cmp(s, key->n) >= 0)
68 return -EINVAL;
69
70 /* (2) m = s^e mod n */
71 return mpi_powm(m, s, key->e, key->n);
72 }
73
74 static inline struct rsa_key *rsa_get_key(struct crypto_akcipher *tfm)
75 {
76 return akcipher_tfm_ctx(tfm);
77 }
78
79 static int rsa_enc(struct akcipher_request *req)
80 {
81 struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
82 const struct rsa_key *pkey = rsa_get_key(tfm);
83 MPI m, c = mpi_alloc(0);
84 int ret = 0;
85 int sign;
86
87 if (!c)
88 return -ENOMEM;
89
90 if (unlikely(!pkey->n || !pkey->e)) {
91 ret = -EINVAL;
92 goto err_free_c;
93 }
94
95 ret = -ENOMEM;
96 m = mpi_read_raw_from_sgl(req->src, req->src_len);
97 if (!m)
98 goto err_free_c;
99
100 ret = _rsa_enc(pkey, c, m);
101 if (ret)
102 goto err_free_m;
103
104 ret = mpi_write_to_sgl(c, req->dst, &req->dst_len, &sign);
105 if (ret)
106 goto err_free_m;
107
108 if (sign < 0)
109 ret = -EBADMSG;
110
111 err_free_m:
112 mpi_free(m);
113 err_free_c:
114 mpi_free(c);
115 return ret;
116 }
117
118 static int rsa_dec(struct akcipher_request *req)
119 {
120 struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
121 const struct rsa_key *pkey = rsa_get_key(tfm);
122 MPI c, m = mpi_alloc(0);
123 int ret = 0;
124 int sign;
125
126 if (!m)
127 return -ENOMEM;
128
129 if (unlikely(!pkey->n || !pkey->d)) {
130 ret = -EINVAL;
131 goto err_free_m;
132 }
133
134 ret = -ENOMEM;
135 c = mpi_read_raw_from_sgl(req->src, req->src_len);
136 if (!c)
137 goto err_free_m;
138
139 ret = _rsa_dec(pkey, m, c);
140 if (ret)
141 goto err_free_c;
142
143 ret = mpi_write_to_sgl(m, req->dst, &req->dst_len, &sign);
144 if (ret)
145 goto err_free_c;
146
147 if (sign < 0)
148 ret = -EBADMSG;
149 err_free_c:
150 mpi_free(c);
151 err_free_m:
152 mpi_free(m);
153 return ret;
154 }
155
156 static int rsa_sign(struct akcipher_request *req)
157 {
158 struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
159 const struct rsa_key *pkey = rsa_get_key(tfm);
160 MPI m, s = mpi_alloc(0);
161 int ret = 0;
162 int sign;
163
164 if (!s)
165 return -ENOMEM;
166
167 if (unlikely(!pkey->n || !pkey->d)) {
168 ret = -EINVAL;
169 goto err_free_s;
170 }
171
172 ret = -ENOMEM;
173 m = mpi_read_raw_from_sgl(req->src, req->src_len);
174 if (!m)
175 goto err_free_s;
176
177 ret = _rsa_sign(pkey, s, m);
178 if (ret)
179 goto err_free_m;
180
181 ret = mpi_write_to_sgl(s, req->dst, &req->dst_len, &sign);
182 if (ret)
183 goto err_free_m;
184
185 if (sign < 0)
186 ret = -EBADMSG;
187
188 err_free_m:
189 mpi_free(m);
190 err_free_s:
191 mpi_free(s);
192 return ret;
193 }
194
195 static int rsa_verify(struct akcipher_request *req)
196 {
197 struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
198 const struct rsa_key *pkey = rsa_get_key(tfm);
199 MPI s, m = mpi_alloc(0);
200 int ret = 0;
201 int sign;
202
203 if (!m)
204 return -ENOMEM;
205
206 if (unlikely(!pkey->n || !pkey->e)) {
207 ret = -EINVAL;
208 goto err_free_m;
209 }
210
211 ret = -ENOMEM;
212 s = mpi_read_raw_from_sgl(req->src, req->src_len);
213 if (!s) {
214 ret = -ENOMEM;
215 goto err_free_m;
216 }
217
218 ret = _rsa_verify(pkey, m, s);
219 if (ret)
220 goto err_free_s;
221
222 ret = mpi_write_to_sgl(m, req->dst, &req->dst_len, &sign);
223 if (ret)
224 goto err_free_s;
225
226 if (sign < 0)
227 ret = -EBADMSG;
228
229 err_free_s:
230 mpi_free(s);
231 err_free_m:
232 mpi_free(m);
233 return ret;
234 }
235
236 static int rsa_check_key_length(unsigned int len)
237 {
238 switch (len) {
239 case 512:
240 case 1024:
241 case 1536:
242 case 2048:
243 case 3072:
244 case 4096:
245 return 0;
246 }
247
248 return -EINVAL;
249 }
250
251 static int rsa_set_pub_key(struct crypto_akcipher *tfm, const void *key,
252 unsigned int keylen)
253 {
254 struct rsa_key *pkey = akcipher_tfm_ctx(tfm);
255 int ret;
256
257 ret = rsa_parse_pub_key(pkey, key, keylen);
258 if (ret)
259 return ret;
260
261 if (rsa_check_key_length(mpi_get_size(pkey->n) << 3)) {
262 rsa_free_key(pkey);
263 ret = -EINVAL;
264 }
265 return ret;
266 }
267
268 static int rsa_set_priv_key(struct crypto_akcipher *tfm, const void *key,
269 unsigned int keylen)
270 {
271 struct rsa_key *pkey = akcipher_tfm_ctx(tfm);
272 int ret;
273
274 ret = rsa_parse_priv_key(pkey, key, keylen);
275 if (ret)
276 return ret;
277
278 if (rsa_check_key_length(mpi_get_size(pkey->n) << 3)) {
279 rsa_free_key(pkey);
280 ret = -EINVAL;
281 }
282 return ret;
283 }
284
285 static int rsa_max_size(struct crypto_akcipher *tfm)
286 {
287 struct rsa_key *pkey = akcipher_tfm_ctx(tfm);
288
289 return pkey->n ? mpi_get_size(pkey->n) : -EINVAL;
290 }
291
292 static void rsa_exit_tfm(struct crypto_akcipher *tfm)
293 {
294 struct rsa_key *pkey = akcipher_tfm_ctx(tfm);
295
296 rsa_free_key(pkey);
297 }
298
299 static struct akcipher_alg rsa = {
300 .encrypt = rsa_enc,
301 .decrypt = rsa_dec,
302 .sign = rsa_sign,
303 .verify = rsa_verify,
304 .set_priv_key = rsa_set_priv_key,
305 .set_pub_key = rsa_set_pub_key,
306 .max_size = rsa_max_size,
307 .exit = rsa_exit_tfm,
308 .base = {
309 .cra_name = "rsa",
310 .cra_driver_name = "rsa-generic",
311 .cra_priority = 100,
312 .cra_module = THIS_MODULE,
313 .cra_ctxsize = sizeof(struct rsa_key),
314 },
315 };
316
317 static int rsa_init(void)
318 {
319 int err;
320
321 err = crypto_register_akcipher(&rsa);
322 if (err)
323 return err;
324
325 err = crypto_register_template(&rsa_pkcs1pad_tmpl);
326 if (err) {
327 crypto_unregister_akcipher(&rsa);
328 return err;
329 }
330
331 return 0;
332 }
333
334 static void rsa_exit(void)
335 {
336 crypto_unregister_template(&rsa_pkcs1pad_tmpl);
337 crypto_unregister_akcipher(&rsa);
338 }
339
340 module_init(rsa_init);
341 module_exit(rsa_exit);
342 MODULE_ALIAS_CRYPTO("rsa");
343 MODULE_LICENSE("GPL");
344 MODULE_DESCRIPTION("RSA generic algorithm");