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authorJiri Kosina <jkosina@suse.cz>2011-09-15 15:08:05 +0200
committerJiri Kosina <jkosina@suse.cz>2011-09-15 15:08:18 +0200
commite060c38434b2caa78efe7cedaff4191040b65a15 (patch)
tree407361230bf6733f63d8e788e4b5e6566ee04818 /Documentation/device-mapper/dm-crypt.txt
parent10e4ac572eeffe5317019bd7330b6058a400dfc2 (diff)
parentcc39c6a9bbdebfcf1a7dee64d83bf302bc38d941 (diff)
Merge branch 'master' into for-next
Fast-forward merge with Linus to be able to merge patches based on more recent version of the tree.
Diffstat (limited to 'Documentation/device-mapper/dm-crypt.txt')
-rw-r--r--Documentation/device-mapper/dm-crypt.txt21
1 files changed, 20 insertions, 1 deletions
diff --git a/Documentation/device-mapper/dm-crypt.txt b/Documentation/device-mapper/dm-crypt.txt
index 6b5c42dbbe8..2c656ae43ba 100644
--- a/Documentation/device-mapper/dm-crypt.txt
+++ b/Documentation/device-mapper/dm-crypt.txt
@@ -4,7 +4,8 @@ dm-crypt
Device-Mapper's "crypt" target provides transparent encryption of block devices
using the kernel crypto API.
-Parameters: <cipher> <key> <iv_offset> <device path> <offset>
+Parameters: <cipher> <key> <iv_offset> <device path> \
+ <offset> [<#opt_params> <opt_params>]
<cipher>
Encryption cipher and an optional IV generation mode.
@@ -37,6 +38,24 @@ Parameters: <cipher> <key> <iv_offset> <device path> <offset>
<offset>
Starting sector within the device where the encrypted data begins.
+<#opt_params>
+ Number of optional parameters. If there are no optional parameters,
+ the optional paramaters section can be skipped or #opt_params can be zero.
+ Otherwise #opt_params is the number of following arguments.
+
+ Example of optional parameters section:
+ 1 allow_discards
+
+allow_discards
+ Block discard requests (a.k.a. TRIM) are passed through the crypt device.
+ The default is to ignore discard requests.
+
+ WARNING: Assess the specific security risks carefully before enabling this
+ option. For example, allowing discards on encrypted devices may lead to
+ the leak of information about the ciphertext device (filesystem type,
+ used space etc.) if the discarded blocks can be located easily on the
+ device later.
+
Example scripts
===============
LUKS (Linux Unified Key Setup) is now the preferred way to set up disk