ddar::metadata Class Reference

Metadata provides key-value paired persistent cache and chunk of volatile memory connected to a file. More...

#include <ddar.h>

List of all members.

Public Member Functions
virtual int	persistent_set (const char *name, const void *value, int size)=0
	Set persistent cache entry.
virtual int	persistent_get (const char *name, void *value)=0
	Get persistent cache entry.
virtual unsigned long	get_inode ()=0
	Returns inode number of the file.
Public Attributes
void *	ephemeral_addr
	Ephemeral cache memory chunk.
int	ephemeral_size
	Size of ephemeral cache memory chunk.
context *	context
	Holds ddar::context object associated to the file.
Static Public Attributes
static constexpr const int	MAX_PERSISTENT_CACHE_NAME_LEN = 32
static constexpr const int	MAX_PERSISTENT_CACHE_VALUE_LEN = 128

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Detailed Description

Metadata provides key-value paired persistent cache and chunk of volatile memory connected to a file.

Metadata objects are always on the stack, hence no need locking and valid only during following crypto functions:

See also:

bool abstract_crypto::prepare(context *context, metadata *md)

bool abstract_crypto::encrypt(metadata *md, void *pt, void *ct, unsigned long page_offset, int page_len)

bool abstract_crypto::decrypt(metadata *md, void *ct, unsigned long page_offset, int page_len)

Persistent cache - Store key-value pairs in persistent memory associated with a file. The crypto plug-in shall store key derivation materials to use later to generate FEK(file encryption key) and also other attributes; such as version info, domain and etc,..

Ephemeral cache - Provides cache in kernel space memory and mmap()ed to the user space address region during crypto operation. The main objective is to avoid storing sensitive information (e.g., FEK) into a persistent memory either user space program has to derive FEK every time before crypto operation. Ephemeral cache is allocated in the kernel, it will be zeroed out in data-lock state together with other sensitive materials associated with the file (e.g., ext4 inode eviction invalidates OEM encryption key)

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Member Function Documentation

virtual int ddar::metadata::persistent_get	(	const char *	name,
		void *	value
	)		[pure virtual]

Get persistent cache entry.

Errors: ~~~ ENODATA The named entry does not exist ENOTSUP Persistent storage is not supported by the file system ~~~

Returns:

On success, return a nonnegative value which is the size of value. On failure, -1 is returned

virtual int ddar::metadata::persistent_set	(	const char *	name,
		const void *	value,
		int	size
	)		[pure virtual]

Set persistent cache entry.

Errors: ~~~ ENOSPC There is insufficient space remaining to store new entry ENOTSUP Persistent storage is not supported by the file system ~~~

Returns:

On success, zero is returned. On failure, -1 is returned

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Member Data Documentation

void* ddar::metadata::ephemeral_addr

Ephemeral cache memory chunk.

ephemeral_addr is only valid within crypto function scope (prepare, encrypt, decrypt) caller should not keep the address and use it later

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The documentation for this class was generated from the following file:

• dualdar/ddar.h