1 /* Crypto operations using stored keys
3 * Copyright (c) 2016, Intel Corporation
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.
11 #include <linux/slab.h>
12 #include <linux/uaccess.h>
13 #include <linux/scatterlist.h>
14 #include <linux/crypto.h>
15 #include <crypto/hash.h>
16 #include <crypto/kpp.h>
17 #include <crypto/dh.h>
18 #include <keys/user-type.h>
21 static ssize_t dh_data_from_key(key_serial_t keyid, void **data)
28 key_ref = lookup_user_key(keyid, 0, KEY_NEED_READ);
29 if (IS_ERR(key_ref)) {
34 key = key_ref_to_ptr(key_ref);
37 if (key->type == &key_type_user) {
39 status = key_validate(key);
41 const struct user_key_payload *payload;
44 payload = user_key_payload_locked(key);
46 duplicate = kmemdup(payload->data, payload->datalen,
50 ret = payload->datalen;
63 static void dh_free_data(struct dh *dh)
70 struct dh_completion {
71 struct completion completion;
75 static void dh_crypto_done(struct crypto_async_request *req, int err)
77 struct dh_completion *compl = req->data;
79 if (err == -EINPROGRESS)
83 complete(&compl->completion);
87 struct shash_desc shash;
91 static int kdf_alloc(struct kdf_sdesc **sdesc_ret, char *hashname)
93 struct crypto_shash *tfm;
94 struct kdf_sdesc *sdesc;
98 /* allocate synchronous hash */
99 tfm = crypto_alloc_shash(hashname, 0, 0);
101 pr_info("could not allocate digest TFM handle %s\n", hashname);
106 if (crypto_shash_digestsize(tfm) == 0)
110 size = sizeof(struct shash_desc) + crypto_shash_descsize(tfm);
111 sdesc = kmalloc(size, GFP_KERNEL);
114 sdesc->shash.tfm = tfm;
115 sdesc->shash.flags = 0x0;
122 crypto_free_shash(tfm);
126 static void kdf_dealloc(struct kdf_sdesc *sdesc)
131 if (sdesc->shash.tfm)
132 crypto_free_shash(sdesc->shash.tfm);
138 * Implementation of the KDF in counter mode according to SP800-108 section 5.1
139 * as well as SP800-56A section 5.8.1 (Single-step KDF).
142 * The src pointer is defined as Z || other info where Z is the shared secret
143 * from DH and other info is an arbitrary string (see SP800-56A section
146 static int kdf_ctr(struct kdf_sdesc *sdesc, const u8 *src, unsigned int slen,
147 u8 *dst, unsigned int dlen, unsigned int zlen)
149 struct shash_desc *desc = &sdesc->shash;
150 unsigned int h = crypto_shash_digestsize(desc->tfm);
153 __be32 counter = cpu_to_be32(1);
156 err = crypto_shash_init(desc);
160 err = crypto_shash_update(desc, (u8 *)&counter, sizeof(__be32));
166 size_t chunk = min_t(size_t, zlen, h);
167 memset(tmpbuffer, 0, chunk);
170 err = crypto_shash_update(desc, tmpbuffer,
176 chunk = min_t(size_t, zlen, h);
181 err = crypto_shash_update(desc, src, slen);
189 err = crypto_shash_final(desc, tmpbuffer);
192 memcpy(dst, tmpbuffer, dlen);
193 memzero_explicit(tmpbuffer, h);
196 err = crypto_shash_final(desc, dst);
202 counter = cpu_to_be32(be32_to_cpu(counter) + 1);
209 memzero_explicit(dst_orig, dlen);
213 static int keyctl_dh_compute_kdf(struct kdf_sdesc *sdesc,
214 char __user *buffer, size_t buflen,
215 uint8_t *kbuf, size_t kbuflen, size_t lzero)
217 uint8_t *outbuf = NULL;
220 outbuf = kmalloc(buflen, GFP_KERNEL);
226 ret = kdf_ctr(sdesc, kbuf, kbuflen, outbuf, buflen, lzero);
231 if (copy_to_user(buffer, outbuf, buflen) != 0)
239 long __keyctl_dh_compute(struct keyctl_dh_params __user *params,
240 char __user *buffer, size_t buflen,
241 struct keyctl_kdf_params *kdfcopy)
247 struct keyctl_dh_params pcopy;
249 struct scatterlist outsg;
250 struct dh_completion compl;
251 struct crypto_kpp *tfm;
252 struct kpp_request *req;
255 struct kdf_sdesc *sdesc = NULL;
257 if (!params || (!buffer && buflen)) {
261 if (copy_from_user(&pcopy, params, sizeof(pcopy)) != 0) {
269 if (buflen > KEYCTL_KDF_MAX_OUTPUT_LEN ||
270 kdfcopy->otherinfolen > KEYCTL_KDF_MAX_OI_LEN) {
275 /* get KDF name string */
276 hashname = strndup_user(kdfcopy->hashname, CRYPTO_MAX_ALG_NAME);
277 if (IS_ERR(hashname)) {
278 ret = PTR_ERR(hashname);
282 /* allocate KDF from the kernel crypto API */
283 ret = kdf_alloc(&sdesc, hashname);
289 memset(&dh_inputs, 0, sizeof(dh_inputs));
291 dlen = dh_data_from_key(pcopy.prime, &dh_inputs.p);
296 dh_inputs.p_size = dlen;
298 dlen = dh_data_from_key(pcopy.base, &dh_inputs.g);
303 dh_inputs.g_size = dlen;
305 dlen = dh_data_from_key(pcopy.private, &dh_inputs.key);
310 dh_inputs.key_size = dlen;
312 secretlen = crypto_dh_key_len(&dh_inputs);
313 secret = kmalloc(secretlen, GFP_KERNEL);
318 ret = crypto_dh_encode_key(secret, secretlen, &dh_inputs);
322 tfm = crypto_alloc_kpp("dh", CRYPTO_ALG_TYPE_KPP, 0);
328 ret = crypto_kpp_set_secret(tfm, secret, secretlen);
332 outlen = crypto_kpp_maxsize(tfm);
336 * When not using a KDF, buflen 0 is used to read the
337 * required buffer length
342 } else if (outlen > buflen) {
348 outbuf = kzalloc(kdfcopy ? (outlen + kdfcopy->otherinfolen) : outlen,
355 sg_init_one(&outsg, outbuf, outlen);
357 req = kpp_request_alloc(tfm, GFP_KERNEL);
363 kpp_request_set_input(req, NULL, 0);
364 kpp_request_set_output(req, &outsg, outlen);
365 init_completion(&compl.completion);
366 kpp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
367 CRYPTO_TFM_REQ_MAY_SLEEP,
368 dh_crypto_done, &compl);
371 * For DH, generate_public_key and generate_shared_secret are
372 * the same calculation
374 ret = crypto_kpp_generate_public_key(req);
375 if (ret == -EINPROGRESS) {
376 wait_for_completion(&compl.completion);
384 * Concatenate SP800-56A otherinfo past DH shared secret -- the
385 * input to the KDF is (DH shared secret || otherinfo)
387 if (copy_from_user(outbuf + req->dst_len, kdfcopy->otherinfo,
388 kdfcopy->otherinfolen) != 0) {
393 ret = keyctl_dh_compute_kdf(sdesc, buffer, buflen, outbuf,
394 req->dst_len + kdfcopy->otherinfolen,
395 outlen - req->dst_len);
396 } else if (copy_to_user(buffer, outbuf, req->dst_len) == 0) {
403 kpp_request_free(req);
407 crypto_free_kpp(tfm);
411 dh_free_data(&dh_inputs);
417 long keyctl_dh_compute(struct keyctl_dh_params __user *params,
418 char __user *buffer, size_t buflen,
419 struct keyctl_kdf_params __user *kdf)
421 struct keyctl_kdf_params kdfcopy;
424 return __keyctl_dh_compute(params, buffer, buflen, NULL);
426 if (copy_from_user(&kdfcopy, kdf, sizeof(kdfcopy)) != 0)
429 return __keyctl_dh_compute(params, buffer, buflen, &kdfcopy);