1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* Crypto operations using stored keys
3 *
4 * Copyright (c) 2016, Intel Corporation
5 */
6
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 <crypto/kdf_sp800108.h>
15 #include <keys/user-type.h>
16 #include "internal.h"
17
dh_data_from_key(key_serial_t keyid,const void ** data)18 static ssize_t dh_data_from_key(key_serial_t keyid, const void **data)
19 {
20 struct key *key;
21 key_ref_t key_ref;
22 long status;
23 ssize_t ret;
24
25 key_ref = lookup_user_key(keyid, 0, KEY_NEED_READ);
26 if (IS_ERR(key_ref)) {
27 ret = -ENOKEY;
28 goto error;
29 }
30
31 key = key_ref_to_ptr(key_ref);
32
33 ret = -EOPNOTSUPP;
34 if (key->type == &key_type_user) {
35 down_read(&key->sem);
36 status = key_validate(key);
37 if (status == 0) {
38 const struct user_key_payload *payload;
39 uint8_t *duplicate;
40
41 payload = user_key_payload_locked(key);
42
43 duplicate = kmemdup(payload->data, payload->datalen,
44 GFP_KERNEL);
45 if (duplicate) {
46 *data = duplicate;
47 ret = payload->datalen;
48 } else {
49 ret = -ENOMEM;
50 }
51 }
52 up_read(&key->sem);
53 }
54
55 key_put(key);
56 error:
57 return ret;
58 }
59
dh_free_data(struct dh * dh)60 static void dh_free_data(struct dh *dh)
61 {
62 kfree_sensitive(dh->key);
63 kfree_sensitive(dh->p);
64 kfree_sensitive(dh->g);
65 }
66
67 struct dh_completion {
68 struct completion completion;
69 int err;
70 };
71
dh_crypto_done(struct crypto_async_request * req,int err)72 static void dh_crypto_done(struct crypto_async_request *req, int err)
73 {
74 struct dh_completion *compl = req->data;
75
76 if (err == -EINPROGRESS)
77 return;
78
79 compl->err = err;
80 complete(&compl->completion);
81 }
82
kdf_alloc(struct crypto_shash ** hash,char * hashname)83 static int kdf_alloc(struct crypto_shash **hash, char *hashname)
84 {
85 struct crypto_shash *tfm;
86
87 /* allocate synchronous hash */
88 tfm = crypto_alloc_shash(hashname, 0, 0);
89 if (IS_ERR(tfm)) {
90 pr_info("could not allocate digest TFM handle %s\n", hashname);
91 return PTR_ERR(tfm);
92 }
93
94 if (crypto_shash_digestsize(tfm) == 0) {
95 crypto_free_shash(tfm);
96 return -EINVAL;
97 }
98
99 *hash = tfm;
100
101 return 0;
102 }
103
kdf_dealloc(struct crypto_shash * hash)104 static void kdf_dealloc(struct crypto_shash *hash)
105 {
106 if (hash)
107 crypto_free_shash(hash);
108 }
109
keyctl_dh_compute_kdf(struct crypto_shash * hash,char __user * buffer,size_t buflen,uint8_t * kbuf,size_t kbuflen)110 static int keyctl_dh_compute_kdf(struct crypto_shash *hash,
111 char __user *buffer, size_t buflen,
112 uint8_t *kbuf, size_t kbuflen)
113 {
114 struct kvec kbuf_iov = { .iov_base = kbuf, .iov_len = kbuflen };
115 uint8_t *outbuf = NULL;
116 int ret;
117 size_t outbuf_len = roundup(buflen, crypto_shash_digestsize(hash));
118
119 outbuf = kmalloc(outbuf_len, GFP_KERNEL);
120 if (!outbuf) {
121 ret = -ENOMEM;
122 goto err;
123 }
124
125 ret = crypto_kdf108_ctr_generate(hash, &kbuf_iov, 1, outbuf, outbuf_len);
126 if (ret)
127 goto err;
128
129 ret = buflen;
130 if (copy_to_user(buffer, outbuf, buflen) != 0)
131 ret = -EFAULT;
132
133 err:
134 kfree_sensitive(outbuf);
135 return ret;
136 }
137
__keyctl_dh_compute(struct keyctl_dh_params __user * params,char __user * buffer,size_t buflen,struct keyctl_kdf_params * kdfcopy)138 long __keyctl_dh_compute(struct keyctl_dh_params __user *params,
139 char __user *buffer, size_t buflen,
140 struct keyctl_kdf_params *kdfcopy)
141 {
142 long ret;
143 ssize_t dlen;
144 int secretlen;
145 int outlen;
146 struct keyctl_dh_params pcopy;
147 struct dh dh_inputs;
148 struct scatterlist outsg;
149 struct dh_completion compl;
150 struct crypto_kpp *tfm;
151 struct kpp_request *req;
152 uint8_t *secret;
153 uint8_t *outbuf;
154 struct crypto_shash *hash = NULL;
155
156 if (!params || (!buffer && buflen)) {
157 ret = -EINVAL;
158 goto out1;
159 }
160 if (copy_from_user(&pcopy, params, sizeof(pcopy)) != 0) {
161 ret = -EFAULT;
162 goto out1;
163 }
164
165 if (kdfcopy) {
166 char *hashname;
167
168 if (memchr_inv(kdfcopy->__spare, 0, sizeof(kdfcopy->__spare))) {
169 ret = -EINVAL;
170 goto out1;
171 }
172
173 if (buflen > KEYCTL_KDF_MAX_OUTPUT_LEN ||
174 kdfcopy->otherinfolen > KEYCTL_KDF_MAX_OI_LEN) {
175 ret = -EMSGSIZE;
176 goto out1;
177 }
178
179 /* get KDF name string */
180 hashname = strndup_user(kdfcopy->hashname, CRYPTO_MAX_ALG_NAME);
181 if (IS_ERR(hashname)) {
182 ret = PTR_ERR(hashname);
183 goto out1;
184 }
185
186 /* allocate KDF from the kernel crypto API */
187 ret = kdf_alloc(&hash, hashname);
188 kfree(hashname);
189 if (ret)
190 goto out1;
191 }
192
193 memset(&dh_inputs, 0, sizeof(dh_inputs));
194
195 dlen = dh_data_from_key(pcopy.prime, &dh_inputs.p);
196 if (dlen < 0) {
197 ret = dlen;
198 goto out1;
199 }
200 dh_inputs.p_size = dlen;
201
202 dlen = dh_data_from_key(pcopy.base, &dh_inputs.g);
203 if (dlen < 0) {
204 ret = dlen;
205 goto out2;
206 }
207 dh_inputs.g_size = dlen;
208
209 dlen = dh_data_from_key(pcopy.private, &dh_inputs.key);
210 if (dlen < 0) {
211 ret = dlen;
212 goto out2;
213 }
214 dh_inputs.key_size = dlen;
215
216 secretlen = crypto_dh_key_len(&dh_inputs);
217 secret = kmalloc(secretlen, GFP_KERNEL);
218 if (!secret) {
219 ret = -ENOMEM;
220 goto out2;
221 }
222 ret = crypto_dh_encode_key(secret, secretlen, &dh_inputs);
223 if (ret)
224 goto out3;
225
226 tfm = crypto_alloc_kpp("dh", 0, 0);
227 if (IS_ERR(tfm)) {
228 ret = PTR_ERR(tfm);
229 goto out3;
230 }
231
232 ret = crypto_kpp_set_secret(tfm, secret, secretlen);
233 if (ret)
234 goto out4;
235
236 outlen = crypto_kpp_maxsize(tfm);
237
238 if (!kdfcopy) {
239 /*
240 * When not using a KDF, buflen 0 is used to read the
241 * required buffer length
242 */
243 if (buflen == 0) {
244 ret = outlen;
245 goto out4;
246 } else if (outlen > buflen) {
247 ret = -EOVERFLOW;
248 goto out4;
249 }
250 }
251
252 outbuf = kzalloc(kdfcopy ? (outlen + kdfcopy->otherinfolen) : outlen,
253 GFP_KERNEL);
254 if (!outbuf) {
255 ret = -ENOMEM;
256 goto out4;
257 }
258
259 sg_init_one(&outsg, outbuf, outlen);
260
261 req = kpp_request_alloc(tfm, GFP_KERNEL);
262 if (!req) {
263 ret = -ENOMEM;
264 goto out5;
265 }
266
267 kpp_request_set_input(req, NULL, 0);
268 kpp_request_set_output(req, &outsg, outlen);
269 init_completion(&compl.completion);
270 kpp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
271 CRYPTO_TFM_REQ_MAY_SLEEP,
272 dh_crypto_done, &compl);
273
274 /*
275 * For DH, generate_public_key and generate_shared_secret are
276 * the same calculation
277 */
278 ret = crypto_kpp_generate_public_key(req);
279 if (ret == -EINPROGRESS) {
280 wait_for_completion(&compl.completion);
281 ret = compl.err;
282 if (ret)
283 goto out6;
284 }
285
286 if (kdfcopy) {
287 /*
288 * Concatenate SP800-56A otherinfo past DH shared secret -- the
289 * input to the KDF is (DH shared secret || otherinfo)
290 */
291 if (copy_from_user(outbuf + req->dst_len, kdfcopy->otherinfo,
292 kdfcopy->otherinfolen) != 0) {
293 ret = -EFAULT;
294 goto out6;
295 }
296
297 ret = keyctl_dh_compute_kdf(hash, buffer, buflen, outbuf,
298 req->dst_len + kdfcopy->otherinfolen);
299 } else if (copy_to_user(buffer, outbuf, req->dst_len) == 0) {
300 ret = req->dst_len;
301 } else {
302 ret = -EFAULT;
303 }
304
305 out6:
306 kpp_request_free(req);
307 out5:
308 kfree_sensitive(outbuf);
309 out4:
310 crypto_free_kpp(tfm);
311 out3:
312 kfree_sensitive(secret);
313 out2:
314 dh_free_data(&dh_inputs);
315 out1:
316 kdf_dealloc(hash);
317 return ret;
318 }
319
keyctl_dh_compute(struct keyctl_dh_params __user * params,char __user * buffer,size_t buflen,struct keyctl_kdf_params __user * kdf)320 long keyctl_dh_compute(struct keyctl_dh_params __user *params,
321 char __user *buffer, size_t buflen,
322 struct keyctl_kdf_params __user *kdf)
323 {
324 struct keyctl_kdf_params kdfcopy;
325
326 if (!kdf)
327 return __keyctl_dh_compute(params, buffer, buflen, NULL);
328
329 if (copy_from_user(&kdfcopy, kdf, sizeof(kdfcopy)) != 0)
330 return -EFAULT;
331
332 return __keyctl_dh_compute(params, buffer, buflen, &kdfcopy);
333 }
334
