// SPDX-License-Identifier: GPL-2.0-or-later
/* Crypto operations using stored keys
*
* Copyright (c) 2016, Intel Corporation
*/
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/scatterlist.h>
#include <linux/crypto.h>
#include <crypto/hash.h>
#include <crypto/kpp.h>
#include <crypto/dh.h>
#include <crypto/kdf_sp800108.h>
#include <keys/user-type.h>
#include "internal.h"
static ssize_t dh_data_from_key(key_serial_t keyid, const void **data)
{
struct key *key;
key_ref_t key_ref;
long status;
ssize_t ret;
key_ref = lookup_user_key(keyid, 0, KEY_NEED_READ);
if (IS_ERR(key_ref)) {
ret = -ENOKEY;
goto error;
}
key = key_ref_to_ptr(key_ref);
ret = -EOPNOTSUPP;
if (key->type == &key_type_user) {
down_read(&key->sem);
status = key_validate(key);
if (status == 0) {
const struct user_key_payload *payload;
uint8_t *duplicate;
payload = user_key_payload_locked(key);
duplicate = kmemdup(payload->data, payload->datalen,
GFP_KERNEL);
if (duplicate) {
*data = duplicate;
ret = payload->datalen;
} else {
ret = -ENOMEM;
}
}
up_read(&key->sem);
}
key_put(key);
error:
return ret;
}
static void dh_free_data(struct dh *dh)
{
kfree_sensitive(dh->key);
kfree_sensitive(dh->p);
kfree_sensitive(dh->g);
}
static int kdf_alloc(struct crypto_shash **hash, char *hashname)
{
struct crypto_shash *tfm;
/* allocate synchronous hash */
tfm = crypto_alloc_shash(hashname, 0, 0);
if (IS_ERR(tfm)) {
pr_info("could not allocate digest TFM handle %s\n", hashname);
return PTR_ERR(tfm);
}
if (crypto_shash_digestsize(tfm) == 0) {
crypto_free_shash(tfm);
return -EINVAL;
}
*hash = tfm;
return 0;
}
static void kdf_dealloc(struct crypto_shash *hash)
{
if (hash)
crypto_free_shash(hash);
}
static int keyctl_dh_compute_kdf(struct crypto_shash *hash,
char __user *buffer, size_t buflen,
uint8_t *kbuf, size_t kbuflen)
{
struct kvec kbuf_iov = { .iov_base = kbuf, .iov_len = kbuflen };
uint8_t *outbuf = NULL;
int ret;
size_t outbuf_len = roundup(buflen, crypto_shash_digestsize(hash));
outbuf = kmalloc(outbuf_len, GFP_KERNEL);
if (!outbuf) {
ret = -ENOMEM;
goto err;
}
ret = crypto_kdf108_ctr_generate(hash, &kbuf_iov, 1, outbuf, outbuf_len);
if (ret)
goto err;
ret = buflen;
if (copy_to_user(buffer, outbuf, buflen) != 0)
ret = -EFAULT;
err:
kfree_sensitive(outbuf);
return ret;
}
long __keyctl_dh_compute(struct keyctl_dh_params __user *params,
char __user *buffer, size_t buflen,
struct keyctl_kdf_params *kdfcopy)
{
long ret;
ssize_t dlen;
int secretlen;
int outlen;
struct keyctl_dh_params pcopy;
struct dh dh_inputs;
struct scatterlist outsg;
DECLARE_CRYPTO_WAIT(compl);
struct crypto_kpp *tfm;
struct kpp_request *req;
uint8_t *secret;
uint8_t *outbuf;
struct crypto_shash *hash = NULL;
if (!params || (!buffer && buflen)) {
ret = -EINVAL;
goto out1;
}
if (copy_from_user(&pcopy, params, sizeof(pcopy)) != 0) {
ret = -EFAULT;
goto out1;
}
if (kdfcopy) {
char *hashname;
if (memchr_inv(kdfcopy->__spare, 0, sizeof(kdfcopy->__spare))) {
ret = -EINVAL;
goto out1;
}
if (buflen > KEYCTL_KDF_MAX_OUTPUT_LEN ||
kdfcopy->otherinfolen > KEYCTL_KDF_MAX_OI_LEN) {
ret = -EMSGSIZE;
goto out1;
}
/* get KDF name string */
hashname = strndup_user(kdfcopy->hashname, CRYPTO_MAX_ALG_NAME);
if (IS_ERR(hashname)) {
ret = PTR_ERR(hashname);
goto out1;
}
/* allocate KDF from the kernel crypto API */
ret = kdf_alloc(&hash, hashname);
kfree(hashname);
if (ret)
goto out1;
}
memset(&dh_inputs, 0, sizeof(dh_inputs));
dlen = dh_data_from_key(pcopy.prime, &dh_inputs.p);
if (dlen < 0) {
ret = dlen;
goto out1;
}
dh_inputs.p_size = dlen;
dlen = dh_data_from_key(pcopy.base, &dh_inputs.g);
if (dlen < 0) {
ret = dlen;
goto out2;
}
dh_inputs.g_size = dlen;
dlen = dh_data_from_key(pcopy.private, &dh_inputs.key);
if (dlen < 0) {
ret = dlen;
goto out2;
}
dh_inputs.key_size = dlen;
secretlen = crypto_dh_key_len(&dh_inputs);
secret = kmalloc(secretlen, GFP_KERNEL);
if (!secret) {
ret = -ENOMEM;
goto out2;
}
ret = crypto_dh_encode_key(secret, secretlen, &dh_inputs);
if (ret)
goto out3;
tfm = crypto_alloc_kpp("dh", 0, 0);
if (IS_ERR(tfm)) {
ret = PTR_ERR(tfm);
goto out3;
}
ret = crypto_kpp_set_secret(tfm, secret, secretlen);
if (ret)
goto out4;
outlen = crypto_kpp_maxsize(tfm);
if (!kdfcopy) {
/*
* When not using a KDF, buflen 0 is used to read the
* required buffer length
*/
if (buflen == 0) {
ret = outlen;
goto out4;
} else if (outlen > buflen) {
ret = -EOVERFLOW;
goto out4;
}
}
outbuf = kzalloc(kdfcopy ? (outlen + kdfcopy->otherinfolen) : outlen,
GFP_KERNEL);
if (!outbuf) {
ret = -ENOMEM;
goto out4;
}
sg_init_one(&outsg, outbuf, outlen);
req = kpp_request_alloc(tfm, GFP_KERNEL);
if (!req) {
ret = -ENOMEM;
goto out5;
}
kpp_request_set_input(req, NULL, 0);
kpp_request_set_output(req, &outsg, outlen);
kpp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
CRYPTO_TFM_REQ_MAY_SLEEP,
crypto_req_done, &compl);
/*
* For DH, generate_public_key and generate_shared_secret are
* the same calculation
*/
ret = crypto_kpp_generate_public_key(req);
ret = crypto_wait_req(ret, &compl);
if (ret)
goto out6;
if (kdfcopy) {
/*
* Concatenate SP800-56A otherinfo past DH shared secret -- the
* input to the KDF is (DH shared secret || otherinfo)
*/
if (copy_from_user(outbuf + req->dst_len, kdfcopy->otherinfo,
kdfcopy->otherinfolen) != 0) {
ret = -EFAULT;
goto out6;
}
ret = keyctl_dh_compute_kdf(hash, buffer, buflen, outbuf,
req->dst_len + kdfcopy->otherinfolen);
} else if (copy_to_user(buffer, outbuf, req->dst_len) == 0) {
ret = req->dst_len;
} else {
ret = -EFAULT;
}
out6:
kpp_request_free(req);
out5:
kfree_sensitive(outbuf);
out4:
crypto_free_kpp(tfm);
out3:
kfree_sensitive(secret);
out2:
dh_free_data(&dh_inputs);
out1:
kdf_dealloc(hash);
return ret;
}
long keyctl_dh_compute(struct keyctl_dh_params __user *params,
char __user *buffer, size_t buflen,
struct keyctl_kdf_params __user *kdf)
{
struct keyctl_kdf_params kdfcopy;
if (!kdf)
return __keyctl_dh_compute(params, buffer, buflen, NULL);
if (copy_from_user(&kdfcopy, kdf, sizeof(kdfcopy)) != 0)
return -EFAULT;
return __keyctl_dh_compute(params, buffer, buflen, &kdfcopy);
}
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