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7#include <linux/slab.h>
8#include <linux/uaccess.h>
9#include <linux/scatterlist.h>
10#include <linux/crypto.h>
11#include <crypto/hash.h>
12#include <crypto/kpp.h>
13#include <crypto/dh.h>
14#include <keys/user-type.h>
15#include "internal.h"
16
17static ssize_t dh_data_from_key(key_serial_t keyid, void **data)
18{
19 struct key *key;
20 key_ref_t key_ref;
21 long status;
22 ssize_t ret;
23
24 key_ref = lookup_user_key(keyid, 0, KEY_NEED_READ);
25 if (IS_ERR(key_ref)) {
26 ret = -ENOKEY;
27 goto error;
28 }
29
30 key = key_ref_to_ptr(key_ref);
31
32 ret = -EOPNOTSUPP;
33 if (key->type == &key_type_user) {
34 down_read(&key->sem);
35 status = key_validate(key);
36 if (status == 0) {
37 const struct user_key_payload *payload;
38 uint8_t *duplicate;
39
40 payload = user_key_payload_locked(key);
41
42 duplicate = kmemdup(payload->data, payload->datalen,
43 GFP_KERNEL);
44 if (duplicate) {
45 *data = duplicate;
46 ret = payload->datalen;
47 } else {
48 ret = -ENOMEM;
49 }
50 }
51 up_read(&key->sem);
52 }
53
54 key_put(key);
55error:
56 return ret;
57}
58
59static void dh_free_data(struct dh *dh)
60{
61 kfree_sensitive(dh->key);
62 kfree_sensitive(dh->p);
63 kfree_sensitive(dh->g);
64}
65
66struct dh_completion {
67 struct completion completion;
68 int err;
69};
70
71static void dh_crypto_done(struct crypto_async_request *req, int err)
72{
73 struct dh_completion *compl = req->data;
74
75 if (err == -EINPROGRESS)
76 return;
77
78 compl->err = err;
79 complete(&compl->completion);
80}
81
82struct kdf_sdesc {
83 struct shash_desc shash;
84 char ctx[];
85};
86
87static int kdf_alloc(struct kdf_sdesc **sdesc_ret, char *hashname)
88{
89 struct crypto_shash *tfm;
90 struct kdf_sdesc *sdesc;
91 int size;
92 int err;
93
94
95 tfm = crypto_alloc_shash(hashname, 0, 0);
96 if (IS_ERR(tfm)) {
97 pr_info("could not allocate digest TFM handle %s\n", hashname);
98 return PTR_ERR(tfm);
99 }
100
101 err = -EINVAL;
102 if (crypto_shash_digestsize(tfm) == 0)
103 goto out_free_tfm;
104
105 err = -ENOMEM;
106 size = sizeof(struct shash_desc) + crypto_shash_descsize(tfm);
107 sdesc = kmalloc(size, GFP_KERNEL);
108 if (!sdesc)
109 goto out_free_tfm;
110 sdesc->shash.tfm = tfm;
111
112 *sdesc_ret = sdesc;
113
114 return 0;
115
116out_free_tfm:
117 crypto_free_shash(tfm);
118 return err;
119}
120
121static void kdf_dealloc(struct kdf_sdesc *sdesc)
122{
123 if (!sdesc)
124 return;
125
126 if (sdesc->shash.tfm)
127 crypto_free_shash(sdesc->shash.tfm);
128
129 kfree_sensitive(sdesc);
130}
131
132
133
134
135
136
137
138
139
140
141
142
143static int kdf_ctr(struct kdf_sdesc *sdesc, const u8 *src, unsigned int slen,
144 u8 *dst, unsigned int dlen, unsigned int zlen)
145{
146 struct shash_desc *desc = &sdesc->shash;
147 unsigned int h = crypto_shash_digestsize(desc->tfm);
148 int err = 0;
149 u8 *dst_orig = dst;
150 __be32 counter = cpu_to_be32(1);
151
152 while (dlen) {
153 err = crypto_shash_init(desc);
154 if (err)
155 goto err;
156
157 err = crypto_shash_update(desc, (u8 *)&counter, sizeof(__be32));
158 if (err)
159 goto err;
160
161 if (zlen && h) {
162 u8 tmpbuffer[32];
163 size_t chunk = min_t(size_t, zlen, sizeof(tmpbuffer));
164 memset(tmpbuffer, 0, chunk);
165
166 do {
167 err = crypto_shash_update(desc, tmpbuffer,
168 chunk);
169 if (err)
170 goto err;
171
172 zlen -= chunk;
173 chunk = min_t(size_t, zlen, sizeof(tmpbuffer));
174 } while (zlen);
175 }
176
177 if (src && slen) {
178 err = crypto_shash_update(desc, src, slen);
179 if (err)
180 goto err;
181 }
182
183 err = crypto_shash_final(desc, dst);
184 if (err)
185 goto err;
186
187 dlen -= h;
188 dst += h;
189 counter = cpu_to_be32(be32_to_cpu(counter) + 1);
190 }
191
192 return 0;
193
194err:
195 memzero_explicit(dst_orig, dlen);
196 return err;
197}
198
199static int keyctl_dh_compute_kdf(struct kdf_sdesc *sdesc,
200 char __user *buffer, size_t buflen,
201 uint8_t *kbuf, size_t kbuflen, size_t lzero)
202{
203 uint8_t *outbuf = NULL;
204 int ret;
205 size_t outbuf_len = roundup(buflen,
206 crypto_shash_digestsize(sdesc->shash.tfm));
207
208 outbuf = kmalloc(outbuf_len, GFP_KERNEL);
209 if (!outbuf) {
210 ret = -ENOMEM;
211 goto err;
212 }
213
214 ret = kdf_ctr(sdesc, kbuf, kbuflen, outbuf, outbuf_len, lzero);
215 if (ret)
216 goto err;
217
218 ret = buflen;
219 if (copy_to_user(buffer, outbuf, buflen) != 0)
220 ret = -EFAULT;
221
222err:
223 kfree_sensitive(outbuf);
224 return ret;
225}
226
227long __keyctl_dh_compute(struct keyctl_dh_params __user *params,
228 char __user *buffer, size_t buflen,
229 struct keyctl_kdf_params *kdfcopy)
230{
231 long ret;
232 ssize_t dlen;
233 int secretlen;
234 int outlen;
235 struct keyctl_dh_params pcopy;
236 struct dh dh_inputs;
237 struct scatterlist outsg;
238 struct dh_completion compl;
239 struct crypto_kpp *tfm;
240 struct kpp_request *req;
241 uint8_t *secret;
242 uint8_t *outbuf;
243 struct kdf_sdesc *sdesc = NULL;
244
245 if (!params || (!buffer && buflen)) {
246 ret = -EINVAL;
247 goto out1;
248 }
249 if (copy_from_user(&pcopy, params, sizeof(pcopy)) != 0) {
250 ret = -EFAULT;
251 goto out1;
252 }
253
254 if (kdfcopy) {
255 char *hashname;
256
257 if (memchr_inv(kdfcopy->__spare, 0, sizeof(kdfcopy->__spare))) {
258 ret = -EINVAL;
259 goto out1;
260 }
261
262 if (buflen > KEYCTL_KDF_MAX_OUTPUT_LEN ||
263 kdfcopy->otherinfolen > KEYCTL_KDF_MAX_OI_LEN) {
264 ret = -EMSGSIZE;
265 goto out1;
266 }
267
268
269 hashname = strndup_user(kdfcopy->hashname, CRYPTO_MAX_ALG_NAME);
270 if (IS_ERR(hashname)) {
271 ret = PTR_ERR(hashname);
272 goto out1;
273 }
274
275
276 ret = kdf_alloc(&sdesc, hashname);
277 kfree(hashname);
278 if (ret)
279 goto out1;
280 }
281
282 memset(&dh_inputs, 0, sizeof(dh_inputs));
283
284 dlen = dh_data_from_key(pcopy.prime, &dh_inputs.p);
285 if (dlen < 0) {
286 ret = dlen;
287 goto out1;
288 }
289 dh_inputs.p_size = dlen;
290
291 dlen = dh_data_from_key(pcopy.base, &dh_inputs.g);
292 if (dlen < 0) {
293 ret = dlen;
294 goto out2;
295 }
296 dh_inputs.g_size = dlen;
297
298 dlen = dh_data_from_key(pcopy.private, &dh_inputs.key);
299 if (dlen < 0) {
300 ret = dlen;
301 goto out2;
302 }
303 dh_inputs.key_size = dlen;
304
305 secretlen = crypto_dh_key_len(&dh_inputs);
306 secret = kmalloc(secretlen, GFP_KERNEL);
307 if (!secret) {
308 ret = -ENOMEM;
309 goto out2;
310 }
311 ret = crypto_dh_encode_key(secret, secretlen, &dh_inputs);
312 if (ret)
313 goto out3;
314
315 tfm = crypto_alloc_kpp("dh", 0, 0);
316 if (IS_ERR(tfm)) {
317 ret = PTR_ERR(tfm);
318 goto out3;
319 }
320
321 ret = crypto_kpp_set_secret(tfm, secret, secretlen);
322 if (ret)
323 goto out4;
324
325 outlen = crypto_kpp_maxsize(tfm);
326
327 if (!kdfcopy) {
328
329
330
331
332 if (buflen == 0) {
333 ret = outlen;
334 goto out4;
335 } else if (outlen > buflen) {
336 ret = -EOVERFLOW;
337 goto out4;
338 }
339 }
340
341 outbuf = kzalloc(kdfcopy ? (outlen + kdfcopy->otherinfolen) : outlen,
342 GFP_KERNEL);
343 if (!outbuf) {
344 ret = -ENOMEM;
345 goto out4;
346 }
347
348 sg_init_one(&outsg, outbuf, outlen);
349
350 req = kpp_request_alloc(tfm, GFP_KERNEL);
351 if (!req) {
352 ret = -ENOMEM;
353 goto out5;
354 }
355
356 kpp_request_set_input(req, NULL, 0);
357 kpp_request_set_output(req, &outsg, outlen);
358 init_completion(&compl.completion);
359 kpp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
360 CRYPTO_TFM_REQ_MAY_SLEEP,
361 dh_crypto_done, &compl);
362
363
364
365
366
367 ret = crypto_kpp_generate_public_key(req);
368 if (ret == -EINPROGRESS) {
369 wait_for_completion(&compl.completion);
370 ret = compl.err;
371 if (ret)
372 goto out6;
373 }
374
375 if (kdfcopy) {
376
377
378
379
380 if (copy_from_user(outbuf + req->dst_len, kdfcopy->otherinfo,
381 kdfcopy->otherinfolen) != 0) {
382 ret = -EFAULT;
383 goto out6;
384 }
385
386 ret = keyctl_dh_compute_kdf(sdesc, buffer, buflen, outbuf,
387 req->dst_len + kdfcopy->otherinfolen,
388 outlen - req->dst_len);
389 } else if (copy_to_user(buffer, outbuf, req->dst_len) == 0) {
390 ret = req->dst_len;
391 } else {
392 ret = -EFAULT;
393 }
394
395out6:
396 kpp_request_free(req);
397out5:
398 kfree_sensitive(outbuf);
399out4:
400 crypto_free_kpp(tfm);
401out3:
402 kfree_sensitive(secret);
403out2:
404 dh_free_data(&dh_inputs);
405out1:
406 kdf_dealloc(sdesc);
407 return ret;
408}
409
410long keyctl_dh_compute(struct keyctl_dh_params __user *params,
411 char __user *buffer, size_t buflen,
412 struct keyctl_kdf_params __user *kdf)
413{
414 struct keyctl_kdf_params kdfcopy;
415
416 if (!kdf)
417 return __keyctl_dh_compute(params, buffer, buflen, NULL);
418
419 if (copy_from_user(&kdfcopy, kdf, sizeof(kdfcopy)) != 0)
420 return -EFAULT;
421
422 return __keyctl_dh_compute(params, buffer, buflen, &kdfcopy);
423}
424
