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