linux-stable/security/keys/dh.c
Nicolai Stange 215bebc8c6 crypto: dh - constify struct dh's pointer members
struct dh contains several pointer members corresponding to DH parameters:
->key, ->p and ->g. A subsequent commit will introduce "dh" wrapping
templates of the form "ffdhe2048(dh)", "ffdhe3072(dh)" and so on in order
to provide built-in support for the well-known safe-prime ffdhe group
parameters specified in RFC 7919. These templates will need to set the
group parameter related members of the (serialized) struct dh instance
passed to the inner "dh" kpp_alg instance, i.e. ->p and ->g, to some
constant, static storage arrays.

Turn the struct dh pointer members' types into "pointer to const" in
preparation for this.

Signed-off-by: Nicolai Stange <nstange@suse.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-03-03 10:47:50 +12:00

333 lines
6.7 KiB
C

// 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);
}
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);
}
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;
struct dh_completion 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);
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(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);
}