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;
121 crypto_free_shash(tfm);
125 static void kdf_dealloc(struct kdf_sdesc *sdesc)
130 if (sdesc->shash.tfm)
131 crypto_free_shash(sdesc->shash.tfm);
137 * Implementation of the KDF in counter mode according to SP800-108 section 5.1
138 * as well as SP800-56A section 5.8.1 (Single-step KDF).
141 * The src pointer is defined as Z || other info where Z is the shared secret
142 * from DH and other info is an arbitrary string (see SP800-56A section
145 * 'dlen' must be a multiple of the digest size.
147 static int kdf_ctr(struct kdf_sdesc *sdesc, const u8 *src, unsigned int slen,
148 u8 *dst, unsigned int dlen, unsigned int zlen)
150 struct shash_desc *desc = &sdesc->shash;
151 unsigned int h = crypto_shash_digestsize(desc->tfm);
154 __be32 counter = cpu_to_be32(1);
157 err = crypto_shash_init(desc);
161 err = crypto_shash_update(desc, (u8 *)&counter, sizeof(__be32));
167 size_t chunk = min_t(size_t, zlen, sizeof(tmpbuffer));
168 memset(tmpbuffer, 0, chunk);
171 err = crypto_shash_update(desc, tmpbuffer,
177 chunk = min_t(size_t, zlen, sizeof(tmpbuffer));
182 err = crypto_shash_update(desc, src, slen);
187 err = crypto_shash_final(desc, dst);
193 counter = cpu_to_be32(be32_to_cpu(counter) + 1);
199 memzero_explicit(dst_orig, dlen);
203 static int keyctl_dh_compute_kdf(struct kdf_sdesc *sdesc,
204 char __user *buffer, size_t buflen,
205 uint8_t *kbuf, size_t kbuflen, size_t lzero)
207 uint8_t *outbuf = NULL;
209 size_t outbuf_len = roundup(buflen,
210 crypto_shash_digestsize(sdesc->shash.tfm));
212 outbuf = kmalloc(outbuf_len, GFP_KERNEL);
218 ret = kdf_ctr(sdesc, kbuf, kbuflen, outbuf, outbuf_len, lzero);
223 if (copy_to_user(buffer, outbuf, buflen) != 0)
231 long __keyctl_dh_compute(struct keyctl_dh_params __user *params,
232 char __user *buffer, size_t buflen,
233 struct keyctl_kdf_params *kdfcopy)
239 struct keyctl_dh_params pcopy;
241 struct scatterlist outsg;
242 struct dh_completion compl;
243 struct crypto_kpp *tfm;
244 struct kpp_request *req;
247 struct kdf_sdesc *sdesc = NULL;
249 if (!params || (!buffer && buflen)) {
253 if (copy_from_user(&pcopy, params, sizeof(pcopy)) != 0) {
261 if (memchr_inv(kdfcopy->__spare, 0, sizeof(kdfcopy->__spare))) {
266 if (buflen > KEYCTL_KDF_MAX_OUTPUT_LEN ||
267 kdfcopy->otherinfolen > KEYCTL_KDF_MAX_OI_LEN) {
272 /* get KDF name string */
273 hashname = strndup_user(kdfcopy->hashname, CRYPTO_MAX_ALG_NAME);
274 if (IS_ERR(hashname)) {
275 ret = PTR_ERR(hashname);
279 /* allocate KDF from the kernel crypto API */
280 ret = kdf_alloc(&sdesc, hashname);
286 memset(&dh_inputs, 0, sizeof(dh_inputs));
288 dlen = dh_data_from_key(pcopy.prime, &dh_inputs.p);
293 dh_inputs.p_size = dlen;
295 dlen = dh_data_from_key(pcopy.base, &dh_inputs.g);
300 dh_inputs.g_size = dlen;
302 dlen = dh_data_from_key(pcopy.private, &dh_inputs.key);
307 dh_inputs.key_size = dlen;
309 secretlen = crypto_dh_key_len(&dh_inputs);
310 secret = kmalloc(secretlen, GFP_KERNEL);
315 ret = crypto_dh_encode_key(secret, secretlen, &dh_inputs);
319 tfm = crypto_alloc_kpp("dh", 0, 0);
325 ret = crypto_kpp_set_secret(tfm, secret, secretlen);
329 outlen = crypto_kpp_maxsize(tfm);
333 * When not using a KDF, buflen 0 is used to read the
334 * required buffer length
339 } else if (outlen > buflen) {
345 outbuf = kzalloc(kdfcopy ? (outlen + kdfcopy->otherinfolen) : outlen,
352 sg_init_one(&outsg, outbuf, outlen);
354 req = kpp_request_alloc(tfm, GFP_KERNEL);
360 kpp_request_set_input(req, NULL, 0);
361 kpp_request_set_output(req, &outsg, outlen);
362 init_completion(&compl.completion);
363 kpp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
364 CRYPTO_TFM_REQ_MAY_SLEEP,
365 dh_crypto_done, &compl);
368 * For DH, generate_public_key and generate_shared_secret are
369 * the same calculation
371 ret = crypto_kpp_generate_public_key(req);
372 if (ret == -EINPROGRESS) {
373 wait_for_completion(&compl.completion);
381 * Concatenate SP800-56A otherinfo past DH shared secret -- the
382 * input to the KDF is (DH shared secret || otherinfo)
384 if (copy_from_user(outbuf + req->dst_len, kdfcopy->otherinfo,
385 kdfcopy->otherinfolen) != 0) {
390 ret = keyctl_dh_compute_kdf(sdesc, buffer, buflen, outbuf,
391 req->dst_len + kdfcopy->otherinfolen,
392 outlen - req->dst_len);
393 } else if (copy_to_user(buffer, outbuf, req->dst_len) == 0) {
400 kpp_request_free(req);
404 crypto_free_kpp(tfm);
408 dh_free_data(&dh_inputs);
414 long keyctl_dh_compute(struct keyctl_dh_params __user *params,
415 char __user *buffer, size_t buflen,
416 struct keyctl_kdf_params __user *kdf)
418 struct keyctl_kdf_params kdfcopy;
421 return __keyctl_dh_compute(params, buffer, buflen, NULL);
423 if (copy_from_user(&kdfcopy, kdf, sizeof(kdfcopy)) != 0)
426 return __keyctl_dh_compute(params, buffer, buflen, &kdfcopy);