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Linux/crypto/rsa.c

  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 
 19 struct 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  */
 29 static 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  */
 43 static 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  */
 57 static 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  */
 71 static 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 
 81 static inline struct rsa_mpi_key *rsa_get_key(struct crypto_akcipher *tfm)
 82 {
 83         return akcipher_tfm_ctx(tfm);
 84 }
 85 
 86 static 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 
118 err_free_m:
119         mpi_free(m);
120 err_free_c:
121         mpi_free(c);
122         return ret;
123 }
124 
125 static 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;
156 err_free_c:
157         mpi_free(c);
158 err_free_m:
159         mpi_free(m);
160         return ret;
161 }
162 
163 static 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 
195 err_free_m:
196         mpi_free(m);
197 err_free_s:
198         mpi_free(s);
199         return ret;
200 }
201 
202 static 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 
236 err_free_s:
237         mpi_free(s);
238 err_free_m:
239         mpi_free(m);
240         return ret;
241 }
242 
243 static 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 
253 static 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 
268 static 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 
297 err:
298         rsa_free_mpi_key(mpi_key);
299         return -ENOMEM;
300 }
301 
302 static 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 
335 err:
336         rsa_free_mpi_key(mpi_key);
337         return -ENOMEM;
338 }
339 
340 static int rsa_max_size(struct crypto_akcipher *tfm)
341 {
342         struct rsa_mpi_key *pkey = akcipher_tfm_ctx(tfm);
343 
344         return pkey->n ? mpi_get_size(pkey->n) : -EINVAL;
345 }
346 
347 static 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 
354 static 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 
372 static 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 
389 static void rsa_exit(void)
390 {
391         crypto_unregister_template(&rsa_pkcs1pad_tmpl);
392         crypto_unregister_akcipher(&rsa);
393 }
394 
395 module_init(rsa_init);
396 module_exit(rsa_exit);
397 MODULE_ALIAS_CRYPTO("rsa");
398 MODULE_LICENSE("GPL");
399 MODULE_DESCRIPTION("RSA generic algorithm");
400 

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