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/*
* kernel keyring utilities
*
* Copyright (C) 2016-2021 Red Hat, Inc. All rights reserved.
* Copyright (C) 2016-2021 Ondrej Kozina
*
* 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.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/syscall.h>
#include "libcryptsetup.h"
#include "utils_keyring.h"
#ifndef HAVE_KEY_SERIAL_T
#define HAVE_KEY_SERIAL_T
typedef int32_t key_serial_t;
#endif
#ifndef ARRAY_SIZE
# define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
#endif
#ifdef KERNEL_KEYRING
static const struct {
key_type_t type;
const char *type_name;
} key_types[] = {
{ LOGON_KEY, "logon" },
{ USER_KEY, "user" },
};
#include <linux/keyctl.h>
/* request_key */
static key_serial_t request_key(const char *type,
const char *description,
const char *callout_info,
key_serial_t keyring)
{
return syscall(__NR_request_key, type, description, callout_info, keyring);
}
/* add_key */
static key_serial_t add_key(const char *type,
const char *description,
const void *payload,
size_t plen,
key_serial_t keyring)
{
return syscall(__NR_add_key, type, description, payload, plen, keyring);
}
/* keyctl_read */
static long keyctl_read(key_serial_t key, char *buffer, size_t buflen)
{
return syscall(__NR_keyctl, KEYCTL_READ, key, buffer, buflen);
}
/* keyctl_revoke */
static long keyctl_revoke(key_serial_t key)
{
return syscall(__NR_keyctl, KEYCTL_REVOKE, key);
}
/* keyctl_unlink */
static long keyctl_unlink(key_serial_t key, key_serial_t keyring)
{
return syscall(__NR_keyctl, KEYCTL_UNLINK, key, keyring);
}
#endif
int keyring_check(void)
{
#ifdef KERNEL_KEYRING
/* logon type key descriptions must be in format "prefix:description" */
return syscall(__NR_request_key, "logon", "dummy", NULL, 0) == -1l && errno != ENOSYS;
#else
return 0;
#endif
}
int keyring_add_key_in_thread_keyring(key_type_t ktype, const char *key_desc, const void *key, size_t key_size)
{
#ifdef KERNEL_KEYRING
key_serial_t kid;
const char *type_name = key_type_name(ktype);
if (!type_name || !key_desc)
return -EINVAL;
kid = add_key(type_name, key_desc, key, key_size, KEY_SPEC_THREAD_KEYRING);
if (kid < 0)
return -errno;
return 0;
#else
return -ENOTSUP;
#endif
}
/* currently used in client utilities only */
int keyring_add_key_in_user_keyring(key_type_t ktype, const char *key_desc, const void *key, size_t key_size)
{
#ifdef KERNEL_KEYRING
const char *type_name = key_type_name(ktype);
key_serial_t kid;
if (!type_name || !key_desc)
return -EINVAL;
kid = add_key(type_name, key_desc, key, key_size, KEY_SPEC_USER_KEYRING);
if (kid < 0)
return -errno;
return 0;
#else
return -ENOTSUP;
#endif
}
/* alias for the same code */
int keyring_get_key(const char *key_desc,
char **key,
size_t *key_size)
{
return keyring_get_passphrase(key_desc, key, key_size);
}
int keyring_get_passphrase(const char *key_desc,
char **passphrase,
size_t *passphrase_len)
{
#ifdef KERNEL_KEYRING
int err;
key_serial_t kid;
long ret;
char *buf = NULL;
size_t len = 0;
do
kid = request_key(key_type_name(USER_KEY), key_desc, NULL, 0);
while (kid < 0 && errno == EINTR);
if (kid < 0)
return -errno;
/* just get payload size */
ret = keyctl_read(kid, NULL, 0);
if (ret > 0) {
len = ret;
buf = malloc(len);
if (!buf)
return -ENOMEM;
/* retrieve actual payload data */
ret = keyctl_read(kid, buf, len);
}
if (ret < 0) {
err = errno;
if (buf)
crypt_safe_memzero(buf, len);
free(buf);
return -err;
}
*passphrase = buf;
*passphrase_len = len;
return 0;
#else
return -ENOTSUP;
#endif
}
static int keyring_revoke_and_unlink_key_type(const char *type_name, const char *key_desc)
{
#ifdef KERNEL_KEYRING
key_serial_t kid;
if (!type_name || !key_desc)
return -EINVAL;
do
kid = request_key(type_name, key_desc, NULL, 0);
while (kid < 0 && errno == EINTR);
if (kid < 0)
return 0;
if (keyctl_revoke(kid))
return -errno;
/*
* best effort only. the key could have been linked
* in some other keyring and its payload is now
* revoked anyway.
*/
keyctl_unlink(kid, KEY_SPEC_THREAD_KEYRING);
keyctl_unlink(kid, KEY_SPEC_PROCESS_KEYRING);
keyctl_unlink(kid, KEY_SPEC_USER_KEYRING);
return 0;
#else
return -ENOTSUP;
#endif
}
const char *key_type_name(key_type_t type)
{
#ifdef KERNEL_KEYRING
unsigned int i;
for (i = 0; i < ARRAY_SIZE(key_types); i++)
if (type == key_types[i].type)
return key_types[i].type_name;
#endif
return NULL;
}
int keyring_revoke_and_unlink_key(key_type_t ktype, const char *key_desc)
{
return keyring_revoke_and_unlink_key_type(key_type_name(ktype), key_desc);
}
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