This adds the admin-guide documentation for dm-inlinecrypt.

dm-inlinecrypt.rst is the guide to using dm-inlinecrypt.

Signed-off-by: Linlin Zhang <linlin.zhang@oss.qualcomm.com>
---
 .../device-mapper/dm-inlinecrypt.rst          | 122 ++++++++++++++++++
 1 file changed, 122 insertions(+)
 create mode 100644 Documentation/admin-guide/device-mapper/dm-inlinecrypt.rst

diff --git a/Documentation/admin-guide/device-mapper/dm-inlinecrypt.rst b/Documentation/admin-guide/device-mapper/dm-inlinecrypt.rst
new file mode 100644
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@@ -0,0 +1,122 @@
+========
+dm-inlinecrypt
+========
+
+Device-Mapper's "inlinecrypt" target provides transparent encryption of block devices
+using the inline encryption hardware.
+
+For a more detailed description of inline encryption, see:
+https://docs.kernel.org/block/inline-encryption.html
+
+Parameters::
+
+	      <cipher> <key> <iv_offset> <device path> \
+	      <offset> [<#opt_params> <opt_params>]
+
+<cipher>
+    Encryption cipher type.
+
+    The cipher specifications format is::
+
+       cipher
+
+    Examples::
+
+       aes-xts-plain64
+
+    The cipher type is correspond one-to-one with encryption modes. For
+    instance, the corresponding crypto mode of aes-xts-plain64 is
+    BLK_ENCRYPTION_MODE_AES_256_XTS.
+
+<key>
+    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.
+    Note that the size in bytes of a valid key must be in bellow range.
+
+        [BLK_CRYPTO_KEY_TYPE_RAW, BLK_CRYPTO_KEY_TYPE_HW_WRAPPED]
+
+<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 'trusted' kernel key type.
+
+<key_description>
+    The kernel keyring key description inlinecrypt target should look for
+    when loading key of <key_type>.
+
+<iv_offset>
+    The IV offset is a sector count that is added to the sector number
+    before creating the IV.
+
+<device path>
+    This is the device that is going to be used as backend and contains the
+    encrypted data.  You can specify it as a path like /dev/xxx or a device
+    number <major>:<minor>.
+
+<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 parameters section can be skipped or #opt_params can be zero.
+    Otherwise #opt_params is the number of following arguments.
+
+    Example of optional parameters section:
+        allow_discards sector_size:4096 iv_large_sectors
+
+allow_discards
+    Block discard requests (a.k.a. TRIM) are passed through the inlinecrypt
+    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.
+
+sector_size:<bytes>
+    Use <bytes> as the encryption unit instead of 512 bytes sectors.
+    This option can be in range 512 - 4096 bytes and must be power of two.
+    Virtual device will announce this size as a minimal IO and logical sector.
+
+iv_large_sectors
+   IV generators will use sector number counted in <sector_size> units
+   instead of default 512 bytes sectors.
+
+   For example, if <sector_size> is 4096 bytes, plain64 IV for the second
+   sector will be 8 (without flag) and 1 if iv_large_sectors is present.
+   The <iv_offset> must be multiple of <sector_size> (in 512 bytes units)
+   if this flag is specified.
+
+Example scripts
+===============
+LUKS (Linux Unified Key Setup) is now the preferred way to set up disk
+encryption with dm-inlinecrypt using the 'cryptsetup' utility, see
+https://gitlab.com/cryptsetup/cryptsetup
+
+::
+
+	#!/bin/sh
+	# Create a inlinecrypt device using dmsetup
+	dmsetup create inlinecrypt1 --table "0 `blockdev --getsz $1` inlinecrypt aes-xts-plain64 babebabebabebabebabebabebabebabebabebabebabebabebabebabebabebabe 0 $1 0"
+
+::
+
+	#!/bin/sh
+	# Create a inlinecrypt device using dmsetup when encryption key is stored in keyring service
+	dmsetup create inlinecrypt2 --table "0 `blockdev --getsz $1` inlinecrypt aes-xts-plain64 :64:logon:fde:dminlinecrypt_test_key 0 $1 0"
+
+::
+
+	#!/bin/sh
+	# Create a inlinecrypt device using cryptsetup and LUKS header with default cipher
+	cryptsetup luksFormat $1
+	cryptsetup luksOpen $1 inlinecrypt1
-- 
2.34.1

On 4/10/26 3:40 PM, Linlin Zhang wrote:
> This adds the admin-guide documentation for dm-inlinecrypt.
> 
> dm-inlinecrypt.rst is the guide to using dm-inlinecrypt.
> 
> Signed-off-by: Linlin Zhang <linlin.zhang@oss.qualcomm.com>
> ---

...

> +
> +<cipher>
> +    Encryption cipher type.
> +
> +    The cipher specifications format is::
> +
> +       cipher
> +
> +    Examples::
> +
> +       aes-xts-plain64
> +
> +    The cipher type is correspond one-to-one with encryption modes. For

... with encryption modes supported for inline crypto in block layer?

In your patch only BLK_ENCRYPTION_MODE_AES_256_XTS.

> +    instance, the corresponding crypto mode of aes-xts-plain64 is
> +    BLK_ENCRYPTION_MODE_AES_256_XTS.

...

> +iv_large_sectors
> +   IV generators will use sector number counted in <sector_size> units
> +   instead of default 512 bytes sectors.
> +
> +   For example, if <sector_size> is 4096 bytes, plain64 IV for the second
> +   sector will be 8 (without flag) and 1 if iv_large_sectors is present.
> +   The <iv_offset> must be multiple of <sector_size> (in 512 bytes units)
> +   if this flag is specified.

Is it true? I see this comment in the code:

/* dm-inlinecrypt doesn't implement iv_large_sectors=false. */

...

> +Example scripts
> +===============
> +LUKS (Linux Unified Key Setup) is now the preferred way to set up disk
> +encryption with dm-inlinecrypt using the 'cryptsetup' utility, see
> +https://gitlab.com/cryptsetup/cryptsetup

Cryptsetup has no support for inlinecrypt and it is question if it should have.
It would require additional options and maybe LUKS2 metadata flag to make it persistent.

How did you test it? Please remove this cryptsetup example.
It can be added later when userspace get this functionality.

...> +
> +	#!/bin/sh
> +	# Create a inlinecrypt device using cryptsetup and LUKS header with default cipher
> +	cryptsetup luksFormat $1
> +	cryptsetup luksOpen $1 inlinecrypt1

ditto. This example will use dm-crypt, not dm-inlinecrypt.

Milan