Merge tag 'fscrypt-for-linus' of git://git.kernel.org/pub/scm/fs/fscrypt/fscrypt

Pull fscrypt updates from Eric Biggers:

 - Add the IV_INO_LBLK_32 encryption policy flag which modifies the
   encryption to be optimized for eMMC inline encryption hardware.

 - Make the test_dummy_encryption mount option for ext4 and f2fs support
   v2 encryption policies.

 - Fix kerneldoc warnings and some coding style inconsistencies.

* tag 'fscrypt-for-linus' of git://git.kernel.org/pub/scm/fs/fscrypt/fscrypt:
  fscrypt: add support for IV_INO_LBLK_32 policies
  fscrypt: make test_dummy_encryption use v2 by default
  fscrypt: support test_dummy_encryption=v2
  fscrypt: add fscrypt_add_test_dummy_key()
  linux/parser.h: add include guards
  fscrypt: remove unnecessary extern keywords
  fscrypt: name all function parameters
  fscrypt: fix all kerneldoc warnings

Documentation/filesystems/f2fs.rst

@@ -225,8 +225,12 @@ fsync_mode=%s          Control the policy of fsync. Currently supports "posix",
                        pass, but the performance will regress. "nobarrier" is
                        based on "posix", but doesn't issue flush command for
                        non-atomic files likewise "nobarrier" mount option.
-test_dummy_encryption  Enable dummy encryption, which provides a fake fscrypt
+test_dummy_encryption
+test_dummy_encryption=%s
+                       Enable dummy encryption, which provides a fake fscrypt
                        context. The fake fscrypt context is used by xfstests.
+                       The argument may be either "v1" or "v2", in order to
+                       select the corresponding fscrypt policy version.
 checkpoint=%s[:%u[%]]  Set to "disable" to turn off checkpointing. Set to "enable"
                        to reenable checkpointing. Is enabled by default. While
                        disabled, any unmounting or unexpected shutdowns will cause

Documentation/filesystems/fscrypt.rst

@@ -292,8 +292,22 @@ files' data differently, inode numbers are included in the IVs.
 Consequently, shrinking the filesystem may not be allowed.
 
 This format is optimized for use with inline encryption hardware
-compliant with the UFS or eMMC standards, which support only 64 IV
-bits per I/O request and may have only a small number of keyslots.
+compliant with the UFS standard, which supports only 64 IV bits per
+I/O request and may have only a small number of keyslots.
+
+IV_INO_LBLK_32 policies
+-----------------------
+
+IV_INO_LBLK_32 policies work like IV_INO_LBLK_64, except that for
+IV_INO_LBLK_32, the inode number is hashed with SipHash-2-4 (where the
+SipHash key is derived from the master key) and added to the file
+logical block number mod 2^32 to produce a 32-bit IV.
+
+This format is optimized for use with inline encryption hardware
+compliant with the eMMC v5.2 standard, which supports only 32 IV bits
+per I/O request and may have only a small number of keyslots.  This
+format results in some level of IV reuse, so it should only be used
+when necessary due to hardware limitations.
 
 Key identifiers
 ---------------
@@ -369,6 +383,10 @@ a little endian number, except that:
   to 32 bits and is placed in bits 0-31 of the IV.  The inode number
   (which is also limited to 32 bits) is placed in bits 32-63.
 
+- With `IV_INO_LBLK_32 policies`_, the logical block number is limited
+  to 32 bits and is placed in bits 0-31 of the IV.  The inode number
+  is then hashed and added mod 2^32.
+
 Note that because file logical block numbers are included in the IVs,
 filesystems must enforce that blocks are never shifted around within
 encrypted files, e.g. via "collapse range" or "insert range".
@@ -465,8 +483,15 @@ This structure must be initialized as follows:
     (0x3).
   - FSCRYPT_POLICY_FLAG_DIRECT_KEY: See `DIRECT_KEY policies`_.
   - FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64: See `IV_INO_LBLK_64
-    policies`_.  This is mutually exclusive with DIRECT_KEY and is not
-    supported on v1 policies.
+    policies`_.
+  - FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32: See `IV_INO_LBLK_32
+    policies`_.
+
+  v1 encryption policies only support the PAD_* and DIRECT_KEY flags.
+  The other flags are only supported by v2 encryption policies.
+
+  The DIRECT_KEY, IV_INO_LBLK_64, and IV_INO_LBLK_32 flags are
+  mutually exclusive.
 
 - For v2 encryption policies, ``__reserved`` must be zeroed.