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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
18static 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);
56error:
57 return ret;
58}
59
60static 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
67static 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
88static void kdf_dealloc(struct crypto_shash *hash)
89{
90 if (hash)
91 crypto_free_shash(hash);
92}
93
94static 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
117err:
118 kfree_sensitive(outbuf);
119 return ret;
120}
121
122long __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
285out6:
286 kpp_request_free(req);
287out5:
288 kfree_sensitive(outbuf);
289out4:
290 crypto_free_kpp(tfm);
291out3:
292 kfree_sensitive(secret);
293out2:
294 dh_free_data(&dh_inputs);
295out1:
296 kdf_dealloc(hash);
297 return ret;
298}
299
300long 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}
1/* Crypto operations using stored keys
2 *
3 * Copyright (c) 2016, Intel Corporation
4 *
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License
7 * as published by the Free Software Foundation; either version
8 * 2 of the License, or (at your option) any later version.
9 */
10
11#include <linux/mpi.h>
12#include <linux/slab.h>
13#include <linux/uaccess.h>
14#include <keys/user-type.h>
15#include "internal.h"
16
17/*
18 * Public key or shared secret generation function [RFC2631 sec 2.1.1]
19 *
20 * ya = g^xa mod p;
21 * or
22 * ZZ = yb^xa mod p;
23 *
24 * where xa is the local private key, ya is the local public key, g is
25 * the generator, p is the prime, yb is the remote public key, and ZZ
26 * is the shared secret.
27 *
28 * Both are the same calculation, so g or yb are the "base" and ya or
29 * ZZ are the "result".
30 */
31static int do_dh(MPI result, MPI base, MPI xa, MPI p)
32{
33 return mpi_powm(result, base, xa, p);
34}
35
36static ssize_t mpi_from_key(key_serial_t keyid, size_t maxlen, MPI *mpi)
37{
38 struct key *key;
39 key_ref_t key_ref;
40 long status;
41 ssize_t ret;
42
43 key_ref = lookup_user_key(keyid, 0, KEY_NEED_READ);
44 if (IS_ERR(key_ref)) {
45 ret = -ENOKEY;
46 goto error;
47 }
48
49 key = key_ref_to_ptr(key_ref);
50
51 ret = -EOPNOTSUPP;
52 if (key->type == &key_type_user) {
53 down_read(&key->sem);
54 status = key_validate(key);
55 if (status == 0) {
56 const struct user_key_payload *payload;
57
58 payload = user_key_payload(key);
59
60 if (maxlen == 0) {
61 *mpi = NULL;
62 ret = payload->datalen;
63 } else if (payload->datalen <= maxlen) {
64 *mpi = mpi_read_raw_data(payload->data,
65 payload->datalen);
66 if (*mpi)
67 ret = payload->datalen;
68 } else {
69 ret = -EINVAL;
70 }
71 }
72 up_read(&key->sem);
73 }
74
75 key_put(key);
76error:
77 return ret;
78}
79
80long keyctl_dh_compute(struct keyctl_dh_params __user *params,
81 char __user *buffer, size_t buflen,
82 void __user *reserved)
83{
84 long ret;
85 MPI base, private, prime, result;
86 unsigned nbytes;
87 struct keyctl_dh_params pcopy;
88 uint8_t *kbuf;
89 ssize_t keylen;
90 size_t resultlen;
91
92 if (!params || (!buffer && buflen)) {
93 ret = -EINVAL;
94 goto out;
95 }
96 if (copy_from_user(&pcopy, params, sizeof(pcopy)) != 0) {
97 ret = -EFAULT;
98 goto out;
99 }
100
101 if (reserved) {
102 ret = -EINVAL;
103 goto out;
104 }
105
106 keylen = mpi_from_key(pcopy.prime, buflen, &prime);
107 if (keylen < 0 || !prime) {
108 /* buflen == 0 may be used to query the required buffer size,
109 * which is the prime key length.
110 */
111 ret = keylen;
112 goto out;
113 }
114
115 /* The result is never longer than the prime */
116 resultlen = keylen;
117
118 keylen = mpi_from_key(pcopy.base, SIZE_MAX, &base);
119 if (keylen < 0 || !base) {
120 ret = keylen;
121 goto error1;
122 }
123
124 keylen = mpi_from_key(pcopy.private, SIZE_MAX, &private);
125 if (keylen < 0 || !private) {
126 ret = keylen;
127 goto error2;
128 }
129
130 result = mpi_alloc(0);
131 if (!result) {
132 ret = -ENOMEM;
133 goto error3;
134 }
135
136 kbuf = kmalloc(resultlen, GFP_KERNEL);
137 if (!kbuf) {
138 ret = -ENOMEM;
139 goto error4;
140 }
141
142 ret = do_dh(result, base, private, prime);
143 if (ret)
144 goto error5;
145
146 ret = mpi_read_buffer(result, kbuf, resultlen, &nbytes, NULL);
147 if (ret != 0)
148 goto error5;
149
150 ret = nbytes;
151 if (copy_to_user(buffer, kbuf, nbytes) != 0)
152 ret = -EFAULT;
153
154error5:
155 kfree(kbuf);
156error4:
157 mpi_free(result);
158error3:
159 mpi_free(private);
160error2:
161 mpi_free(base);
162error1:
163 mpi_free(prime);
164out:
165 return ret;
166}