From 9c8268def6127a9d9888b822a74becb80dfeab6f Mon Sep 17 00:00:00 2001
From: Joe Richey <joerichey@google.com>
Date: Thu, 6 Apr 2017 16:14:05 -0700
Subject: fscrypt: Move key structure and constants to uapi

This commit exposes the necessary constants and structures for a
userspace program to pass filesystem encryption keys into the keyring.
The fscrypt_key structure was already part of the kernel ABI, this
change just makes it so programs no longer have to redeclare these
structures (like e4crypt in e2fsprogs currently does).

Note that we do not expose the other FS_*_KEY_SIZE constants as they are
not necessary. Only XTS is supported for contents_encryption_mode, so
currently FS_MAX_KEY_SIZE bytes of key material must always be passed to
the kernel.

This commit also removes __packed from fscrypt_key as it does not
contain any implicit padding and does not refer to an on-disk structure.

Signed-off-by: Joe Richey <joerichey@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
 include/uapi/linux/fs.h | 13 +++++++++++++
 1 file changed, 13 insertions(+)

(limited to 'include/uapi/linux/fs.h')

diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
index 048a85e9f017..9691fda01245 100644
--- a/include/uapi/linux/fs.h
+++ b/include/uapi/linux/fs.h
@@ -285,6 +285,19 @@ struct fscrypt_policy {
 #define FS_IOC_GET_ENCRYPTION_PWSALT	_IOW('f', 20, __u8[16])
 #define FS_IOC_GET_ENCRYPTION_POLICY	_IOW('f', 21, struct fscrypt_policy)
 
+/* Parameters for passing an encryption key into the kernel keyring */
+#define FS_KEY_DESC_PREFIX		"fscrypt:"
+#define FS_KEY_DESC_PREFIX_SIZE		8
+
+/* Structure that userspace passes to the kernel keyring */
+#define FS_MAX_KEY_SIZE			64
+
+struct fscrypt_key {
+	__u32 mode;
+	__u8 raw[FS_MAX_KEY_SIZE];
+	__u32 size;
+};
+
 /*
  * Inode flags (FS_IOC_GETFLAGS / FS_IOC_SETFLAGS)
  *
-- 
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