// 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 <keys/user-type.h>
#include "internal.h"
static ssize_t dh_data_from_key(key_serial_t keyid, 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)
{
kzfree(dh->key);
kzfree(dh->p);
kzfree(dh->g);
}
struct dh_completion {
struct completion completion;
int err;
};
static void dh_crypto_done(struct crypto_async_request *req, int err)
{
struct dh_completion *compl = req->data;
if (err == -EINPROGRESS)
return;
compl->err = err;
complete(&compl->completion);
}
struct kdf_sdesc {
struct shash_desc shash;
char ctx[];
};
static int kdf_alloc(struct kdf_sdesc **sdesc_ret, char *hashname)
{
struct crypto_shash *tfm;
struct kdf_sdesc *sdesc;
int size;
int err;
/* 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);
}
err = -EINVAL;
if (crypto_shash_digestsize(tfm) == 0)
goto out_free_tfm;
err = -ENOMEM;
size = sizeof(struct shash_desc) + crypto_shash_descsize(tfm);
sdesc = kmalloc(size, GFP_KERNEL);
if (!sdesc)
goto out_free_tfm;
sdesc->shash.tfm = tfm;
*sdesc_ret = sdesc;
return 0;
out_free_tfm:
crypto_free_shash(tfm);
return err;
}
static void kdf_dealloc(struct kdf_sdesc *sdesc)
{
if (!sdesc)
return;
if (sdesc->shash.tfm)
crypto_free_shash(sdesc->shash.tfm);
kzfree(sdesc);
}
/*
* Implementation of the KDF in counter mode according to SP800-108 section 5.1
* as well as SP800-56A section 5.8.1 (Single-step KDF).
*
* SP800-56A:
* The src pointer is defined as Z || other info where Z is the shared secret
* from DH and other info is an arbitrary string (see SP800-56A section
* 5.8.1.2).
*
* 'dlen' must be a multiple of the digest size.
*/
static int kdf_ctr(struct kdf_sdesc *sdesc, const u8 *src, unsigned int slen,
u8 *dst, unsigned int dlen, unsigned int zlen)
{
struct shash_desc *desc = &sdesc->shash;
unsigned int h = crypto_shash_digestsize(desc->tfm);
int err = 0;
u8 *dst_orig = dst;
__be32 counter = cpu_to_be32(1);
while (dlen) {
err = crypto_shash_init(desc);
if (err)
goto err;
err = crypto_shash_update(desc, (u8 *)&counter, sizeof(__be32));
if (err)
goto err;
if (zlen && h) {
u8 tmpbuffer[32];
size_t chunk = min_t(size_t, zlen, sizeof(tmpbuffer));
memset(tmpbuffer, 0, chunk);
do {
err = crypto_shash_update(desc, tmpbuffer,
chunk);
if (err)
goto err;
zlen -= chunk;
chunk = min_t(size_t, zlen, sizeof(tmpbuffer));
} while (zlen);
}
if (src && slen) {
err = crypto_shash_update(desc, src, slen);
if (err)
goto err;
}
err = crypto_shash_final(desc, dst);
if (err)
goto err;
dlen -= h;
dst += h;
counter = cpu_to_be32(be32_to_cpu(counter) + 1);
}
return 0;
err:
memzero_explicit(dst_orig, dlen);
return err;
}
static int keyctl_dh_compute_kdf(struct kdf_sdesc *sdesc,
char __user *buffer, size_t buflen,
uint8_t *kbuf, size_t kbuflen, size_t lzero)
{
uint8_t *outbuf = NULL;
int ret;
size_t outbuf_len = roundup(buflen,
crypto_shash_digestsize(sdesc->shash.tfm));
outbuf = kmalloc(outbuf_len, GFP_KERNEL);
if (!outbuf) {
ret = -ENOMEM;
goto err;
}
ret = kdf_ctr(sdesc, kbuf, kbuflen, outbuf, outbuf_len, lzero);
if (ret)
goto err;
ret = buflen;
if (copy_to_user(buffer, outbuf, buflen) != 0)
ret = -EFAULT;
err:
kzfree(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;
struct dh_completion compl;
struct crypto_kpp *tfm;
struct kpp_request *req;
uint8_t *secret;
uint8_t *outbuf;
struct kdf_sdesc *sdesc = 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(&sdesc, 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);
init_completion(&compl.completion);
kpp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
CRYPTO_TFM_REQ_MAY_SLEEP,
dh_crypto_done, &compl);
/*
* For DH, generate_public_key and generate_shared_secret are
* the same calculation
*/
ret = crypto_kpp_generate_public_key(req);
if (ret == -EINPROGRESS) {
wait_for_completion(&compl.completion);
ret = compl.err;
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(sdesc, buffer, buflen, outbuf,
req->dst_len + kdfcopy->otherinfolen,
outlen - req->dst_len);
} else if (copy_to_user(buffer, outbuf, req->dst_len) == 0) {
ret = req->dst_len;
} else {
ret = -EFAULT;
}
out6:
kpp_request_free(req);
out5:
kzfree(outbuf);
out4:
crypto_free_kpp(tfm);
out3:
kzfree(secret);
out2:
dh_free_data(&dh_inputs);
out1:
kdf_dealloc(sdesc);
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);
}
