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authorOndrej Kozina <okozina@redhat.com>2016-11-21 15:58:51 +0100
committerMike Snitzer <snitzer@redhat.com>2016-12-08 14:13:09 -0500
commitc538f6ec9f56996677c58cfd1f7f8108b0a944cb (patch)
treee035520dd97d5cd8644a66e28c65879287e42082 /Documentation/device-mapper
parent0637018dff106e2591c1baa628e27a24a37ccf44 (diff)
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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>
Diffstat (limited to 'Documentation/device-mapper')
-rw-r--r--Documentation/device-mapper/dm-crypt.txt25
1 files changed, 24 insertions, 1 deletions
diff --git a/Documentation/device-mapper/dm-crypt.txt b/Documentation/device-mapper/dm-crypt.txt
index 692171fe9da0..6f15fcea9566 100644
--- a/Documentation/device-mapper/dm-crypt.txt
+++ b/Documentation/device-mapper/dm-crypt.txt
@@ -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;
@@ -90,6 +107,12 @@ dmsetup create crypt1 --table "0 `blockdev --getsize $1` crypt aes-cbc-essiv:sha
[[
#!/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
cryptsetup luksFormat $1
cryptsetup luksOpen $1 crypt1