mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-12 13:55:32 +00:00
![Denis Efremov](/assets/img/avatar_default.png)
Use kvfree_sensitive() instead of open-coding it. Signed-off-by: Denis Efremov <efremov@linux.com> Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Reviewed-by: Ben Boeckel <mathstuf@gmail.com>
291 lines
6.6 KiB
C
291 lines
6.6 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
|
|
/* Large capacity key type
|
|
*
|
|
* Copyright (C) 2017-2020 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
|
|
* Copyright (C) 2013 Red Hat, Inc. All Rights Reserved.
|
|
* Written by David Howells (dhowells@redhat.com)
|
|
*/
|
|
|
|
#define pr_fmt(fmt) "big_key: "fmt
|
|
#include <linux/init.h>
|
|
#include <linux/seq_file.h>
|
|
#include <linux/file.h>
|
|
#include <linux/shmem_fs.h>
|
|
#include <linux/err.h>
|
|
#include <linux/random.h>
|
|
#include <keys/user-type.h>
|
|
#include <keys/big_key-type.h>
|
|
#include <crypto/chacha20poly1305.h>
|
|
|
|
/*
|
|
* Layout of key payload words.
|
|
*/
|
|
enum {
|
|
big_key_data,
|
|
big_key_path,
|
|
big_key_path_2nd_part,
|
|
big_key_len,
|
|
};
|
|
|
|
/*
|
|
* If the data is under this limit, there's no point creating a shm file to
|
|
* hold it as the permanently resident metadata for the shmem fs will be at
|
|
* least as large as the data.
|
|
*/
|
|
#define BIG_KEY_FILE_THRESHOLD (sizeof(struct inode) + sizeof(struct dentry))
|
|
|
|
/*
|
|
* big_key defined keys take an arbitrary string as the description and an
|
|
* arbitrary blob of data as the payload
|
|
*/
|
|
struct key_type key_type_big_key = {
|
|
.name = "big_key",
|
|
.preparse = big_key_preparse,
|
|
.free_preparse = big_key_free_preparse,
|
|
.instantiate = generic_key_instantiate,
|
|
.revoke = big_key_revoke,
|
|
.destroy = big_key_destroy,
|
|
.describe = big_key_describe,
|
|
.read = big_key_read,
|
|
.update = big_key_update,
|
|
};
|
|
|
|
/*
|
|
* Preparse a big key
|
|
*/
|
|
int big_key_preparse(struct key_preparsed_payload *prep)
|
|
{
|
|
struct path *path = (struct path *)&prep->payload.data[big_key_path];
|
|
struct file *file;
|
|
u8 *buf, *enckey;
|
|
ssize_t written;
|
|
size_t datalen = prep->datalen;
|
|
size_t enclen = datalen + CHACHA20POLY1305_AUTHTAG_SIZE;
|
|
int ret;
|
|
|
|
if (datalen <= 0 || datalen > 1024 * 1024 || !prep->data)
|
|
return -EINVAL;
|
|
|
|
/* Set an arbitrary quota */
|
|
prep->quotalen = 16;
|
|
|
|
prep->payload.data[big_key_len] = (void *)(unsigned long)datalen;
|
|
|
|
if (datalen > BIG_KEY_FILE_THRESHOLD) {
|
|
/* Create a shmem file to store the data in. This will permit the data
|
|
* to be swapped out if needed.
|
|
*
|
|
* File content is stored encrypted with randomly generated key.
|
|
* Since the key is random for each file, we can set the nonce
|
|
* to zero, provided we never define a ->update() call.
|
|
*/
|
|
loff_t pos = 0;
|
|
|
|
buf = kvmalloc(enclen, GFP_KERNEL);
|
|
if (!buf)
|
|
return -ENOMEM;
|
|
|
|
/* generate random key */
|
|
enckey = kmalloc(CHACHA20POLY1305_KEY_SIZE, GFP_KERNEL);
|
|
if (!enckey) {
|
|
ret = -ENOMEM;
|
|
goto error;
|
|
}
|
|
ret = get_random_bytes_wait(enckey, CHACHA20POLY1305_KEY_SIZE);
|
|
if (unlikely(ret))
|
|
goto err_enckey;
|
|
|
|
/* encrypt data */
|
|
chacha20poly1305_encrypt(buf, prep->data, datalen, NULL, 0,
|
|
0, enckey);
|
|
|
|
/* save aligned data to file */
|
|
file = shmem_kernel_file_setup("", enclen, 0);
|
|
if (IS_ERR(file)) {
|
|
ret = PTR_ERR(file);
|
|
goto err_enckey;
|
|
}
|
|
|
|
written = kernel_write(file, buf, enclen, &pos);
|
|
if (written != enclen) {
|
|
ret = written;
|
|
if (written >= 0)
|
|
ret = -EIO;
|
|
goto err_fput;
|
|
}
|
|
|
|
/* Pin the mount and dentry to the key so that we can open it again
|
|
* later
|
|
*/
|
|
prep->payload.data[big_key_data] = enckey;
|
|
*path = file->f_path;
|
|
path_get(path);
|
|
fput(file);
|
|
kvfree_sensitive(buf, enclen);
|
|
} else {
|
|
/* Just store the data in a buffer */
|
|
void *data = kmalloc(datalen, GFP_KERNEL);
|
|
|
|
if (!data)
|
|
return -ENOMEM;
|
|
|
|
prep->payload.data[big_key_data] = data;
|
|
memcpy(data, prep->data, prep->datalen);
|
|
}
|
|
return 0;
|
|
|
|
err_fput:
|
|
fput(file);
|
|
err_enckey:
|
|
kfree_sensitive(enckey);
|
|
error:
|
|
kvfree_sensitive(buf, enclen);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Clear preparsement.
|
|
*/
|
|
void big_key_free_preparse(struct key_preparsed_payload *prep)
|
|
{
|
|
if (prep->datalen > BIG_KEY_FILE_THRESHOLD) {
|
|
struct path *path = (struct path *)&prep->payload.data[big_key_path];
|
|
|
|
path_put(path);
|
|
}
|
|
kfree_sensitive(prep->payload.data[big_key_data]);
|
|
}
|
|
|
|
/*
|
|
* dispose of the links from a revoked keyring
|
|
* - called with the key sem write-locked
|
|
*/
|
|
void big_key_revoke(struct key *key)
|
|
{
|
|
struct path *path = (struct path *)&key->payload.data[big_key_path];
|
|
|
|
/* clear the quota */
|
|
key_payload_reserve(key, 0);
|
|
if (key_is_positive(key) &&
|
|
(size_t)key->payload.data[big_key_len] > BIG_KEY_FILE_THRESHOLD)
|
|
vfs_truncate(path, 0);
|
|
}
|
|
|
|
/*
|
|
* dispose of the data dangling from the corpse of a big_key key
|
|
*/
|
|
void big_key_destroy(struct key *key)
|
|
{
|
|
size_t datalen = (size_t)key->payload.data[big_key_len];
|
|
|
|
if (datalen > BIG_KEY_FILE_THRESHOLD) {
|
|
struct path *path = (struct path *)&key->payload.data[big_key_path];
|
|
|
|
path_put(path);
|
|
path->mnt = NULL;
|
|
path->dentry = NULL;
|
|
}
|
|
kfree_sensitive(key->payload.data[big_key_data]);
|
|
key->payload.data[big_key_data] = NULL;
|
|
}
|
|
|
|
/*
|
|
* Update a big key
|
|
*/
|
|
int big_key_update(struct key *key, struct key_preparsed_payload *prep)
|
|
{
|
|
int ret;
|
|
|
|
ret = key_payload_reserve(key, prep->datalen);
|
|
if (ret < 0)
|
|
return ret;
|
|
|
|
if (key_is_positive(key))
|
|
big_key_destroy(key);
|
|
|
|
return generic_key_instantiate(key, prep);
|
|
}
|
|
|
|
/*
|
|
* describe the big_key key
|
|
*/
|
|
void big_key_describe(const struct key *key, struct seq_file *m)
|
|
{
|
|
size_t datalen = (size_t)key->payload.data[big_key_len];
|
|
|
|
seq_puts(m, key->description);
|
|
|
|
if (key_is_positive(key))
|
|
seq_printf(m, ": %zu [%s]",
|
|
datalen,
|
|
datalen > BIG_KEY_FILE_THRESHOLD ? "file" : "buff");
|
|
}
|
|
|
|
/*
|
|
* read the key data
|
|
* - the key's semaphore is read-locked
|
|
*/
|
|
long big_key_read(const struct key *key, char *buffer, size_t buflen)
|
|
{
|
|
size_t datalen = (size_t)key->payload.data[big_key_len];
|
|
long ret;
|
|
|
|
if (!buffer || buflen < datalen)
|
|
return datalen;
|
|
|
|
if (datalen > BIG_KEY_FILE_THRESHOLD) {
|
|
struct path *path = (struct path *)&key->payload.data[big_key_path];
|
|
struct file *file;
|
|
u8 *buf, *enckey = (u8 *)key->payload.data[big_key_data];
|
|
size_t enclen = datalen + CHACHA20POLY1305_AUTHTAG_SIZE;
|
|
loff_t pos = 0;
|
|
|
|
buf = kvmalloc(enclen, GFP_KERNEL);
|
|
if (!buf)
|
|
return -ENOMEM;
|
|
|
|
file = dentry_open(path, O_RDONLY, current_cred());
|
|
if (IS_ERR(file)) {
|
|
ret = PTR_ERR(file);
|
|
goto error;
|
|
}
|
|
|
|
/* read file to kernel and decrypt */
|
|
ret = kernel_read(file, buf, enclen, &pos);
|
|
if (ret != enclen) {
|
|
if (ret >= 0)
|
|
ret = -EIO;
|
|
goto err_fput;
|
|
}
|
|
|
|
ret = chacha20poly1305_decrypt(buf, buf, enclen, NULL, 0, 0,
|
|
enckey) ? 0 : -EBADMSG;
|
|
if (unlikely(ret))
|
|
goto err_fput;
|
|
|
|
ret = datalen;
|
|
|
|
/* copy out decrypted data */
|
|
memcpy(buffer, buf, datalen);
|
|
|
|
err_fput:
|
|
fput(file);
|
|
error:
|
|
kvfree_sensitive(buf, enclen);
|
|
} else {
|
|
ret = datalen;
|
|
memcpy(buffer, key->payload.data[big_key_data], datalen);
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Register key type
|
|
*/
|
|
static int __init big_key_init(void)
|
|
{
|
|
return register_key_type(&key_type_big_key);
|
|
}
|
|
|
|
late_initcall(big_key_init);
|