dm crypt: add ability to use keys from the kernel key retention service
The kernel key service is a generic way to store keys for the use of other subsystems. Currently there is no way to use kernel keys in dm-crypt. This patch aims to fix that. Instead of key userspace may pass a key description with preceding ':'. So message that constructs encryption mapping now looks like this: <cipher> [<key>|:<key_string>] <iv_offset> <dev_path> <start> [<#opt_params> <opt_params>] where <key_string> is in format: <key_size>:<key_type>:<key_description> Currently we only support two elementary key types: 'user' and 'logon'. Keys may be loaded in dm-crypt either via <key_string> or using classical method and pass the key in hex representation directly. dm-crypt device initialised with a key passed in hex representation may be replaced with key passed in key_string format and vice versa. (Based on original work by Andrey Ryabinin) Signed-off-by: Ondrej Kozina <okozina@redhat.com> Reviewed-by: David Howells <dhowells@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Ondrej Kozina
Mike Snitzer
parent
0637018dff
commit
c538f6ec9f
|
|
@ -21,13 +21,30 @@ Parameters: <cipher> <key> <iv_offset> <device path> \
|
|||
/proc/crypto contains supported crypto modes
|
||||
|
||||
<key>
|
||||
Key used for encryption. It is encoded as a hexadecimal number.
|
||||
Key used for encryption. It is encoded either as a hexadecimal number
|
||||
or it can be passed as <key_string> prefixed with single colon
|
||||
character (':') for keys residing in kernel keyring service.
|
||||
You can only use key sizes that are valid for the selected cipher
|
||||
in combination with the selected iv mode.
|
||||
Note that for some iv modes the key string can contain additional
|
||||
keys (for example IV seed) so the key contains more parts concatenated
|
||||
into a single string.
|
||||
|
||||
<key_string>
|
||||
The kernel keyring key is identified by string in following format:
|
||||
<key_size>:<key_type>:<key_description>.
|
||||
|
||||
<key_size>
|
||||
The encryption key size in bytes. The kernel key payload size must match
|
||||
the value passed in <key_size>.
|
||||
|
||||
<key_type>
|
||||
Either 'logon' or 'user' kernel key type.
|
||||
|
||||
<key_description>
|
||||
The kernel keyring key description crypt target should look for
|
||||
when loading key of <key_type>.
|
||||
|
||||
<keycount>
|
||||
Multi-key compatibility mode. You can define <keycount> keys and
|
||||
then sectors are encrypted according to their offsets (sector 0 uses key0;
|
||||
|
|
@ -88,6 +105,12 @@ https://gitlab.com/cryptsetup/cryptsetup
|
|||
dmsetup create crypt1 --table "0 `blockdev --getsize $1` crypt aes-cbc-essiv:sha256 babebabebabebabebabebabebabebabe 0 $1 0"
|
||||
]]
|
||||
|
||||
[[
|
||||
#!/bin/sh
|
||||
# Create a crypt device using dmsetup when encryption key is stored in keyring service
|
||||
dmsetup create crypt2 --table "0 `blockdev --getsize $1` crypt aes-cbc-essiv:sha256 :32:logon:my_prefix:my_key 0 $1 0"
|
||||
]]
|
||||
|
||||
[[
|
||||
#!/bin/sh
|
||||
# Create a crypt device using cryptsetup and LUKS header with default cipher
|
||||
|
|
|
|||
|
|
@ -12,6 +12,7 @@
|
|||
#include <linux/module.h>
|
||||
#include <linux/init.h>
|
||||
#include <linux/kernel.h>
|
||||
#include <linux/key.h>
|
||||
#include <linux/bio.h>
|
||||
#include <linux/blkdev.h>
|
||||
#include <linux/mempool.h>
|
||||
|
|
@ -29,6 +30,7 @@
|
|||
#include <crypto/md5.h>
|
||||
#include <crypto/algapi.h>
|
||||
#include <crypto/skcipher.h>
|
||||
#include <keys/user-type.h>
|
||||
|
||||
#include <linux/device-mapper.h>
|
||||
|
||||
|
|
@ -140,6 +142,7 @@ struct crypt_config {
|
|||
|
||||
char *cipher;
|
||||
char *cipher_string;
|
||||
char *key_string;
|
||||
|
||||
const struct crypt_iv_operations *iv_gen_ops;
|
||||
union {
|
||||
|
|
@ -1484,22 +1487,134 @@ static int crypt_setkey(struct crypt_config *cc)
|
|||
return err;
|
||||
}
|
||||
|
||||
#ifdef CONFIG_KEYS
|
||||
|
||||
static int crypt_set_keyring_key(struct crypt_config *cc, const char *key_string)
|
||||
{
|
||||
char *new_key_string, *key_desc;
|
||||
int ret;
|
||||
struct key *key;
|
||||
const struct user_key_payload *ukp;
|
||||
|
||||
/* look for next ':' separating key_type from key_description */
|
||||
key_desc = strpbrk(key_string, ":");
|
||||
if (!key_desc || key_desc == key_string || !strlen(key_desc + 1))
|
||||
return -EINVAL;
|
||||
|
||||
if (strncmp(key_string, "logon:", key_desc - key_string + 1) &&
|
||||
strncmp(key_string, "user:", key_desc - key_string + 1))
|
||||
return -EINVAL;
|
||||
|
||||
new_key_string = kstrdup(key_string, GFP_KERNEL);
|
||||
if (!new_key_string)
|
||||
return -ENOMEM;
|
||||
|
||||
key = request_key(key_string[0] == 'l' ? &key_type_logon : &key_type_user,
|
||||
key_desc + 1, NULL);
|
||||
if (IS_ERR(key)) {
|
||||
kzfree(new_key_string);
|
||||
return PTR_ERR(key);
|
||||
}
|
||||
|
||||
rcu_read_lock();
|
||||
|
||||
ukp = user_key_payload(key);
|
||||
if (!ukp) {
|
||||
rcu_read_unlock();
|
||||
key_put(key);
|
||||
kzfree(new_key_string);
|
||||
return -EKEYREVOKED;
|
||||
}
|
||||
|
||||
if (cc->key_size != ukp->datalen) {
|
||||
rcu_read_unlock();
|
||||
key_put(key);
|
||||
kzfree(new_key_string);
|
||||
return -EINVAL;
|
||||
}
|
||||
|
||||
memcpy(cc->key, ukp->data, cc->key_size);
|
||||
|
||||
rcu_read_unlock();
|
||||
key_put(key);
|
||||
|
||||
/* clear the flag since following operations may invalidate previously valid key */
|
||||
clear_bit(DM_CRYPT_KEY_VALID, &cc->flags);
|
||||
|
||||
ret = crypt_setkey(cc);
|
||||
|
||||
/* wipe the kernel key payload copy in each case */
|
||||
memset(cc->key, 0, cc->key_size * sizeof(u8));
|
||||
|
||||
if (!ret) {
|
||||
set_bit(DM_CRYPT_KEY_VALID, &cc->flags);
|
||||
kzfree(cc->key_string);
|
||||
cc->key_string = new_key_string;
|
||||
} else
|
||||
kzfree(new_key_string);
|
||||
|
||||
return ret;
|
||||
}
|
||||
|
||||
static int get_key_size(char **key_string)
|
||||
{
|
||||
char *colon, dummy;
|
||||
int ret;
|
||||
|
||||
if (*key_string[0] != ':')
|
||||
return strlen(*key_string) >> 1;
|
||||
|
||||
/* look for next ':' in key string */
|
||||
colon = strpbrk(*key_string + 1, ":");
|
||||
if (!colon)
|
||||
return -EINVAL;
|
||||
|
||||
if (sscanf(*key_string + 1, "%u%c", &ret, &dummy) != 2 || dummy != ':')
|
||||
return -EINVAL;
|
||||
|
||||
*key_string = colon;
|
||||
|
||||
/* remaining key string should be :<logon|user>:<key_desc> */
|
||||
|
||||
return ret;
|
||||
}
|
||||
|
||||
#else
|
||||
|
||||
static int crypt_set_keyring_key(struct crypt_config *cc, const char *key_string)
|
||||
{
|
||||
return -EINVAL;
|
||||
}
|
||||
|
||||
static int get_key_size(char **key_string)
|
||||
{
|
||||
return (*key_string[0] == ':') ? -EINVAL : strlen(*key_string) >> 1;
|
||||
}
|
||||
|
||||
#endif
|
||||
|
||||
static int crypt_set_key(struct crypt_config *cc, char *key)
|
||||
{
|
||||
int r = -EINVAL;
|
||||
int key_string_len = strlen(key);
|
||||
|
||||
/* The key size may not be changed. */
|
||||
if (cc->key_size != (key_string_len >> 1))
|
||||
goto out;
|
||||
|
||||
/* Hyphen (which gives a key_size of zero) means there is no key. */
|
||||
if (!cc->key_size && strcmp(key, "-"))
|
||||
goto out;
|
||||
|
||||
/* ':' means the key is in kernel keyring, short-circuit normal key processing */
|
||||
if (key[0] == ':') {
|
||||
r = crypt_set_keyring_key(cc, key + 1);
|
||||
goto out;
|
||||
}
|
||||
|
||||
/* clear the flag since following operations may invalidate previously valid key */
|
||||
clear_bit(DM_CRYPT_KEY_VALID, &cc->flags);
|
||||
|
||||
/* wipe references to any kernel keyring key */
|
||||
kzfree(cc->key_string);
|
||||
cc->key_string = NULL;
|
||||
|
||||
if (cc->key_size && crypt_decode_key(cc->key, key, cc->key_size) < 0)
|
||||
goto out;
|
||||
|
||||
|
|
@ -1518,6 +1633,8 @@ static int crypt_wipe_key(struct crypt_config *cc)
|
|||
{
|
||||
clear_bit(DM_CRYPT_KEY_VALID, &cc->flags);
|
||||
memset(&cc->key, 0, cc->key_size * sizeof(u8));
|
||||
kzfree(cc->key_string);
|
||||
cc->key_string = NULL;
|
||||
|
||||
return crypt_setkey(cc);
|
||||
}
|
||||
|
|
@ -1555,6 +1672,7 @@ static void crypt_dtr(struct dm_target *ti)
|
|||
|
||||
kzfree(cc->cipher);
|
||||
kzfree(cc->cipher_string);
|
||||
kzfree(cc->key_string);
|
||||
|
||||
/* Must zero key material before freeing */
|
||||
kzfree(cc);
|
||||
|
|
@ -1723,12 +1841,13 @@ static int crypt_ctr_cipher(struct dm_target *ti,
|
|||
|
||||
/*
|
||||
* Construct an encryption mapping:
|
||||
* <cipher> <key> <iv_offset> <dev_path> <start>
|
||||
* <cipher> [<key>|:<key_size>:<user|logon>:<key_description>] <iv_offset> <dev_path> <start>
|
||||
*/
|
||||
static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
|
||||
{
|
||||
struct crypt_config *cc;
|
||||
unsigned int key_size, opt_params;
|
||||
int key_size;
|
||||
unsigned int opt_params;
|
||||
unsigned long long tmpll;
|
||||
int ret;
|
||||
size_t iv_size_padding;
|
||||
|
|
@ -1745,7 +1864,11 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
|
|||
return -EINVAL;
|
||||
}
|
||||
|
||||
key_size = strlen(argv[1]) >> 1;
|
||||
key_size = get_key_size(&argv[1]);
|
||||
if (key_size < 0) {
|
||||
ti->error = "Cannot parse key size";
|
||||
return -EINVAL;
|
||||
}
|
||||
|
||||
cc = kzalloc(sizeof(*cc) + key_size * sizeof(u8), GFP_KERNEL);
|
||||
if (!cc) {
|
||||
|
|
@ -1952,10 +2075,13 @@ static void crypt_status(struct dm_target *ti, status_type_t type,
|
|||
case STATUSTYPE_TABLE:
|
||||
DMEMIT("%s ", cc->cipher_string);
|
||||
|
||||
if (cc->key_size > 0)
|
||||
for (i = 0; i < cc->key_size; i++)
|
||||
DMEMIT("%02x", cc->key[i]);
|
||||
else
|
||||
if (cc->key_size > 0) {
|
||||
if (cc->key_string)
|
||||
DMEMIT(":%u:%s", cc->key_size, cc->key_string);
|
||||
else
|
||||
for (i = 0; i < cc->key_size; i++)
|
||||
DMEMIT("%02x", cc->key[i]);
|
||||
} else
|
||||
DMEMIT("-");
|
||||
|
||||
DMEMIT(" %llu %s %llu", (unsigned long long)cc->iv_offset,
|
||||
|
|
@ -2011,7 +2137,7 @@ static void crypt_resume(struct dm_target *ti)
|
|||
static int crypt_message(struct dm_target *ti, unsigned argc, char **argv)
|
||||
{
|
||||
struct crypt_config *cc = ti->private;
|
||||
int ret = -EINVAL;
|
||||
int key_size, ret = -EINVAL;
|
||||
|
||||
if (argc < 2)
|
||||
goto error;
|
||||
|
|
@ -2022,6 +2148,13 @@ static int crypt_message(struct dm_target *ti, unsigned argc, char **argv)
|
|||
return -EINVAL;
|
||||
}
|
||||
if (argc == 3 && !strcasecmp(argv[1], "set")) {
|
||||
/* The key size may not be changed. */
|
||||
key_size = get_key_size(&argv[2]);
|
||||
if (key_size < 0 || cc->key_size != key_size) {
|
||||
memset(argv[2], '0', strlen(argv[2]));
|
||||
return -EINVAL;
|
||||
}
|
||||
|
||||
ret = crypt_set_key(cc, argv[2]);
|
||||
if (ret)
|
||||
return ret;
|
||||
|
|
@ -2065,7 +2198,7 @@ static void crypt_io_hints(struct dm_target *ti, struct queue_limits *limits)
|
|||
|
||||
static struct target_type crypt_target = {
|
||||
.name = "crypt",
|
||||
.version = {1, 14, 1},
|
||||
.version = {1, 15, 0},
|
||||
.module = THIS_MODULE,
|
||||
.ctr = crypt_ctr,
|
||||
.dtr = crypt_dtr,
|
||||
|
|
|
|||
Loading…
Reference in New Issue