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|
/* Crypto operations using stored keys
*
* Copyright (c) 2016, Intel Corporation
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#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(hashna
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