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
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
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 static int kdf_alloc(struct crypto_shash **hash, char *hashname)
68 {
69 struct crypto_shash *tfm;
70
71 /* allocate synchronous hash */
72 tfm = crypto_alloc_shash(hashname, 0, 0);
73 if (IS_ERR(tfm)) {
74 pr_info("could not allocate digest TFM handle %s\n", hashname);
75 return PTR_ERR(tfm);
76 }
77
78 if (crypto_shash_digestsize(tfm) == 0) {
79 crypto_free_shash(tfm);
80 return -EINVAL;
81 }
82
83 *hash = tfm;
84
85 return 0;
86 }
87
88 static void kdf_dealloc(struct crypto_shash *hash)
89 {
90 if (hash)
91 crypto_free_shash(hash);
92 }
93
94 static int keyctl_dh_compute_kdf(struct crypto_shash *hash,
95 char __user *buffer, size_t buflen,
96 uint8_t *kbuf, size_t kbuflen)
97 {
98 struct kvec kbuf_iov = { .iov_base = kbuf, .iov_len = kbuflen };
99 uint8_t *outbuf = NULL;
100 int ret;
101 size_t outbuf_len = roundup(buflen, crypto_shash_digestsize(hash));
102
103 outbuf = kmalloc(outbuf_len, GFP_KERNEL);
104 if (!outbuf) {
105 ret = -ENOMEM;
106 goto err;
107 }
108
109 ret = crypto_kdf108_ctr_generate(hash, &kbuf_iov, 1, outbuf, outbuf_len);
110 if (ret)
111 goto err;
112
113 ret = buflen;
114 if (copy_to_user(buffer, outbuf, buflen) != 0)
115 ret = -EFAULT;
116
117 err:
118 kfree_sensitive(outbuf);
119 return ret;
120 }
121
122 long __keyctl_dh_compute(struct keyctl_dh_params __user *params,
123 char __user *buffer, size_t buflen,
124 struct keyctl_kdf_params *kdfcopy)
125 {
126 long ret;
127 ssize_t dlen;
128 int secretlen;
129 int outlen;
130 struct keyctl_dh_params pcopy;
131 struct dh dh_inputs;
132 struct scatterlist outsg;
133 DECLARE_CRYPTO_WAIT(compl);
134 struct crypto_kpp *tfm;
135 struct kpp_request *req;
136 uint8_t *secret;
137 uint8_t *outbuf;
138 struct crypto_shash *hash = NULL;
139
140 if (!params || (!buffer && buflen)) {
141 ret = -EINVAL;
142 goto out1;
143 }
144 if (copy_from_user(&pcopy, params, sizeof(pcopy)) != 0) {
145 ret = -EFAULT;
146 goto out1;
147 }
148
149 if (kdfcopy) {
150 char *hashname;
151
152 if (memchr_inv(kdfcopy->__spare, 0, sizeof(kdfcopy->__spare))) {
153 ret = -EINVAL;
154 goto out1;
155 }
156
157 if (buflen > KEYCTL_KDF_MAX_OUTPUT_LEN ||
158 kdfcopy->otherinfolen > KEYCTL_KDF_MAX_OI_LEN) {
159 ret = -EMSGSIZE;
160 goto out1;
161 }
162
163 /* get KDF name string */
164 hashname = strndup_user(kdfcopy->hashname, CRYPTO_MAX_ALG_NAME);
165 if (IS_ERR(hashname)) {
166 ret = PTR_ERR(hashname);
167 goto out1;
168 }
169
170 /* allocate KDF from the kernel crypto API */
171 ret = kdf_alloc(&hash, hashname);
172 kfree(hashname);
173 if (ret)
174 goto out1;
175 }
176
177 memset(&dh_inputs, 0, sizeof(dh_inputs));
178
179 dlen = dh_data_from_key(pcopy.prime, &dh_inputs.p);
180 if (dlen < 0) {
181 ret = dlen;
182 goto out1;
183 }
184 dh_inputs.p_size = dlen;
185
186 dlen = dh_data_from_key(pcopy.base, &dh_inputs.g);
187 if (dlen < 0) {
188 ret = dlen;
189 goto out2;
190 }
191 dh_inputs.g_size = dlen;
192
193 dlen = dh_data_from_key(pcopy.private, &dh_inputs.key);
194 if (dlen < 0) {
195 ret = dlen;
196 goto out2;
197 }
198 dh_inputs.key_size = dlen;
199
200 secretlen = crypto_dh_key_len(&dh_inputs);
201 secret = kmalloc(secretlen, GFP_KERNEL);
202 if (!secret) {
203 ret = -ENOMEM;
204 goto out2;
205 }
206 ret = crypto_dh_encode_key(secret, secretlen, &dh_inputs);
207 if (ret)
208 goto out3;
209
210 tfm = crypto_alloc_kpp("dh", 0, 0);
211 if (IS_ERR(tfm)) {
212 ret = PTR_ERR(tfm);
213 goto out3;
214 }
215
216 ret = crypto_kpp_set_secret(tfm, secret, secretlen);
217 if (ret)
218 goto out4;
219
220 outlen = crypto_kpp_maxsize(tfm);
221
222 if (!kdfcopy) {
223 /*
224 * When not using a KDF, buflen 0 is used to read the
225 * required buffer length
226 */
227 if (buflen == 0) {
228 ret = outlen;
229 goto out4;
230 } else if (outlen > buflen) {
231 ret = -EOVERFLOW;
232 goto out4;
233 }
234 }
235
236 outbuf = kzalloc(kdfcopy ? (outlen + kdfcopy->otherinfolen) : outlen,
237 GFP_KERNEL);
238 if (!outbuf) {
239 ret = -ENOMEM;
240 goto out4;
241 }
242
243 sg_init_one(&outsg, outbuf, outlen);
244
245 req = kpp_request_alloc(tfm, GFP_KERNEL);
246 if (!req) {
247 ret = -ENOMEM;
248 goto out5;
249 }
250
251 kpp_request_set_input(req, NULL, 0);
252 kpp_request_set_output(req, &outsg, outlen);
253 kpp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
254 CRYPTO_TFM_REQ_MAY_SLEEP,
255 crypto_req_done, &compl);
256
257 /*
258 * For DH, generate_public_key and generate_shared_secret are
259 * the same calculation
260 */
261 ret = crypto_kpp_generate_public_key(req);
262 ret = crypto_wait_req(ret, &compl);
263 if (ret)
264 goto out6;
265
266 if (kdfcopy) {
267 /*
268 * Concatenate SP800-56A otherinfo past DH shared secret -- the
269 * input to the KDF is (DH shared secret || otherinfo)
270 */
271 if (copy_from_user(outbuf + req->dst_len, kdfcopy->otherinfo,
272 kdfcopy->otherinfolen) != 0) {
273 ret = -EFAULT;
274 goto out6;
275 }
276
277 ret = keyctl_dh_compute_kdf(hash, buffer, buflen, outbuf,
278 req->dst_len + kdfcopy->otherinfolen);
279 } else if (copy_to_user(buffer, outbuf, req->dst_len) == 0) {
280 ret = req->dst_len;
281 } else {
282 ret = -EFAULT;
283 }
284
285 out6:
286 kpp_request_free(req);
287 out5:
288 kfree_sensitive(outbuf);
289 out4:
290 crypto_free_kpp(tfm);
291 out3:
292 kfree_sensitive(secret);
293 out2:
294 dh_free_data(&dh_inputs);
295 out1:
296 kdf_dealloc(hash);
297 return ret;
298 }
299
300 long keyctl_dh_compute(struct keyctl_dh_params __user *params,
301 char __user *buffer, size_t buflen,
302 struct keyctl_kdf_params __user *kdf)
303 {
304 struct keyctl_kdf_params kdfcopy;
305
306 if (!kdf)
307 return __keyctl_dh_compute(params, buffer, buflen, NULL);
308
309 if (copy_from_user(&kdfcopy, kdf, sizeof(kdfcopy)) != 0)
310 return -EFAULT;
311
312 return __keyctl_dh_compute(params, buffer, buflen, &kdfcopy);
313 }
314
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