On Mon, Nov 21 2016 at 9:58P -0500,
Ondrej Kozina <okozina@xxxxxxxxxx> wrote:
> Changes since v2:
> - moved rcu_read_lock() closer to key payload processing (thanks Mikulas)
> - updated dm-crypt documentation
> - updated code comments and unified parameter names in kernel keyring function stubs
> (#CONFIG_KEYS undefined)
>
> 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.
>
> (Patch is based on original work by Andrey Ryabinin)
>
> Signed-off-by: Ondrej Kozina <okozina@xxxxxxxxxx>
Other than the following cleanup patch that I've put ontop of your v3,
looks good to me.
diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 7c2bbef..8fcc924 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -1508,12 +1508,8 @@ static int crypt_set_keyring_key(struct crypt_config *cc, const char *key_string
if (!new_key_string)
return -ENOMEM;
- /*
- * FIXME: are there any key descriptions we should disallow users
- * from loading to dm-crypt? i.e.: kernel keys starting with '.'
- */
-
- key = request_key(strncmp(key_string, "user", 4) ? &key_type_logon : &key_type_user, key_desc + 1, NULL);
+ key = request_key(strncmp(key_string, "user", 4) ? &key_type_logon : &key_type_user,
+ key_desc + 1, NULL);
if (IS_ERR(key)) {
kzfree(new_key_string);
return PTR_ERR(key);
@@ -1602,25 +1598,25 @@ static int crypt_set_key(struct crypt_config *cc, char *key)
if (!cc->key_size && strcmp(key, "-"))
goto out;
- /* ':' means that the key is in kernel keyring */
- if (key[0] == ':')
+ /* ':' means the key is in kernel keyring, short-circuit normal key processing */
+ if (key[0] == ':') {
r = crypt_set_keyring_key(cc, key + 1);
- else {
- /* clear the flag since following operations may invalidate previously valid key */
- clear_bit(DM_CRYPT_KEY_VALID, &cc->flags);
+ goto out;
+ }
- /* wipe references to any kernel keyring key */
- kzfree(cc->key_string);
- cc->key_string = NULL;
+ /* clear the flag since following operations may invalidate previously valid key */
+ clear_bit(DM_CRYPT_KEY_VALID, &cc->flags);
- if (cc->key_size &&
- crypt_decode_key(cc->key, key, cc->key_size) < 0)
- goto out;
+ /* wipe references to any kernel keyring key */
+ kzfree(cc->key_string);
+ cc->key_string = NULL;
- r = crypt_setkey(cc);
- if (!r)
- set_bit(DM_CRYPT_KEY_VALID, &cc->flags);
- }
+ if (cc->key_size && crypt_decode_key(cc->key, key, cc->key_size) < 0)
+ goto out;
+
+ r = crypt_setkey(cc);
+ if (!r)
+ set_bit(DM_CRYPT_KEY_VALID, &cc->flags);
out:
/* Hex key string not needed after here, so wipe it. */
memset(key, '0', key_string_len);
--
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