1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* Crypto operations using stored keys
4 * Copyright (c) 2016, Intel Corporation
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>
18 static ssize_t dh_data_from_key(key_serial_t keyid, const void **data)
25 key_ref = lookup_user_key(keyid, 0, KEY_NEED_READ);
26 if (IS_ERR(key_ref)) {
31 key = key_ref_to_ptr(key_ref);
34 if (key->type == &key_type_user) {
36 status = key_validate(key);
38 const struct user_key_payload *payload;
41 payload = user_key_payload_locked(key);
43 duplicate = kmemdup(payload->data, payload->datalen,
47 ret = payload->datalen;
60 static void dh_free_data(struct dh *dh)
62 kfree_sensitive(dh->key);
63 kfree_sensitive(dh->p);
64 kfree_sensitive(dh->g);
67 static int kdf_alloc(struct crypto_shash **hash, char *hashname)
69 struct crypto_shash *tfm;
71 /* allocate synchronous hash */
72 tfm = crypto_alloc_shash(hashname, 0, 0);
74 pr_info("could not allocate digest TFM handle %s\n", hashname);
78 if (crypto_shash_digestsize(tfm) == 0) {
79 crypto_free_shash(tfm);
88 static void kdf_dealloc(struct crypto_shash *hash)
91 crypto_free_shash(hash);
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)
98 struct kvec kbuf_iov = { .iov_base = kbuf, .iov_len = kbuflen };
99 uint8_t *outbuf = NULL;
101 size_t outbuf_len = roundup(buflen, crypto_shash_digestsize(hash));
103 outbuf = kmalloc(outbuf_len, GFP_KERNEL);
109 ret = crypto_kdf108_ctr_generate(hash, &kbuf_iov, 1, outbuf, outbuf_len);
114 if (copy_to_user(buffer, outbuf, buflen) != 0)
118 kfree_sensitive(outbuf);
122 long __keyctl_dh_compute(struct keyctl_dh_params __user *params,
123 char __user *buffer, size_t buflen,
124 struct keyctl_kdf_params *kdfcopy)
130 struct keyctl_dh_params pcopy;
132 struct scatterlist outsg;
133 DECLARE_CRYPTO_WAIT(compl);
134 struct crypto_kpp *tfm;
135 struct kpp_request *req;
138 struct crypto_shash *hash = NULL;
140 if (!params || (!buffer && buflen)) {
144 if (copy_from_user(&pcopy, params, sizeof(pcopy)) != 0) {
152 if (memchr_inv(kdfcopy->__spare, 0, sizeof(kdfcopy->__spare))) {
157 if (buflen > KEYCTL_KDF_MAX_OUTPUT_LEN ||
158 kdfcopy->otherinfolen > KEYCTL_KDF_MAX_OI_LEN) {
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);
170 /* allocate KDF from the kernel crypto API */
171 ret = kdf_alloc(&hash, hashname);
177 memset(&dh_inputs, 0, sizeof(dh_inputs));
179 dlen = dh_data_from_key(pcopy.prime, &dh_inputs.p);
184 dh_inputs.p_size = dlen;
186 dlen = dh_data_from_key(pcopy.base, &dh_inputs.g);
191 dh_inputs.g_size = dlen;
193 dlen = dh_data_from_key(pcopy.private, &dh_inputs.key);
198 dh_inputs.key_size = dlen;
200 secretlen = crypto_dh_key_len(&dh_inputs);
201 secret = kmalloc(secretlen, GFP_KERNEL);
206 ret = crypto_dh_encode_key(secret, secretlen, &dh_inputs);
210 tfm = crypto_alloc_kpp("dh", 0, 0);
216 ret = crypto_kpp_set_secret(tfm, secret, secretlen);
220 outlen = crypto_kpp_maxsize(tfm);
224 * When not using a KDF, buflen 0 is used to read the
225 * required buffer length
230 } else if (outlen > buflen) {
236 outbuf = kzalloc(kdfcopy ? (outlen + kdfcopy->otherinfolen) : outlen,
243 sg_init_one(&outsg, outbuf, outlen);
245 req = kpp_request_alloc(tfm, GFP_KERNEL);
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);
258 * For DH, generate_public_key and generate_shared_secret are
259 * the same calculation
261 ret = crypto_kpp_generate_public_key(req);
262 ret = crypto_wait_req(ret, &compl);
268 * Concatenate SP800-56A otherinfo past DH shared secret -- the
269 * input to the KDF is (DH shared secret || otherinfo)
271 if (copy_from_user(outbuf + req->dst_len, kdfcopy->otherinfo,
272 kdfcopy->otherinfolen) != 0) {
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) {
286 kpp_request_free(req);
288 kfree_sensitive(outbuf);
290 crypto_free_kpp(tfm);
292 kfree_sensitive(secret);
294 dh_free_data(&dh_inputs);
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)
304 struct keyctl_kdf_params kdfcopy;
307 return __keyctl_dh_compute(params, buffer, buflen, NULL);
309 if (copy_from_user(&kdfcopy, kdf, sizeof(kdfcopy)) != 0)
312 return __keyctl_dh_compute(params, buffer, buflen, &kdfcopy);