path: root/fs/jfs/xattr.c

/*
 *   Copyright (C) International Business Machines  Corp., 2000-2004
 *   Copyright (C) Christoph Hellwig, 2002
 *
 *   This program is free software;  you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY;  without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
 *   the GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program;  if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#include <linux/capability.h>
#include <linux/fs.h>
#include <linux/xattr.h>
#include <linux/posix_acl_xattr.h>
#include <linux/quotaops.h>
#include <linux/security.h>
#include "jfs_incore.h"
#include "jfs_superblock.h"
#include "jfs_dmap.h"
#include "jfs_debug.h"
#include "jfs_dinode.h"
#include "jfs_extent.h"
#include "jfs_metapage.h"
#include "jfs_xattr.h"
#include "jfs_acl.h"

/*
 *	jfs_xattr.c: extended attribute service
 *
 * Overall design --
 *
 * Format:
 *
 *   Extended attribute lists (jfs_ea_list) consist of an overall size (32 bit
 *   value) and a variable (0 or more) number of extended attribute
 *   entries.  Each extended attribute entry (jfs_ea) is a <name,value> double
 *   where <name> is constructed from a null-terminated ascii string
 *   (1 ... 255 bytes in the name) and <value> is arbitrary 8 bit data
 *   (1 ... 65535 bytes).  The in-memory format is
 *
 *   0       1        2        4                4 + namelen + 1
 *   +-------+--------+--------+----------------+-------------------+
 *   | Flags | Name   | Value  | Name String \0 | Data . . . .      |
 *   |       | Length | Length |                |                   |
 *   +-------+--------+--------+----------------+-------------------+
 *
 *   A jfs_ea_list then is structured as
 *
 *   0            4                   4 + EA_SIZE(ea1)
 *   +------------+-------------------+--------------------+-----
 *   | Overall EA | First FEA Element | Second FEA Element | .....
 *   | List Size  |                   |                    |
 *   +------------+-------------------+--------------------+-----
 *
 *   On-disk:
 *
 *	FEALISTs are stored on disk using blocks allocated by dbAlloc() and
 *	written directly. An EA list may be in-lined in the inode if there is
 *	sufficient room available.
 */

struct ea_buffer {
	int flag;		/* Indicates what storage xattr points to */
	int max_size;		/* largest xattr that fits in current buffer */
	dxd_t new_ea;		/* dxd to replace ea when modifying xattr */
	struct metapage *mp;	/* metapage containing ea list */
	struct jfs_ea_list *xattr;	/* buffer containing ea list */
};

/*
 * ea_buffer.flag values
 */
#define EA_INLINE	0x0001
#define EA_EXTENT	0x0002
#define EA_NEW		0x0004
#define EA_MALLOC	0x0008


/*
 * These three routines are used to recognize on-disk extended attributes
 * that are in a recognized namespace.  If the attribute is not recognized,
 * "os2." is prepended to the name
 */
static inline int is_os2_xattr(struct jfs_ea *ea)
{
	/*
	 * Check for "system."
	 */
	if ((ea->namelen >= XATTR_SYSTEM_PREFIX_LEN) &&
	    !strncmp(ea->name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
		return false;
	/*
	 * Check for "user."
	 */
	if ((ea->namelen >= XATTR_USER_PREFIX_LEN) &&
	    !strncmp(ea->name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN))
		return false;
	/*
	 * Check for "security."
	 */
	if ((ea->namelen >= XATTR_SECURITY_PREFIX_LEN) &&
	    !strncmp(ea->name, XATTR_SECURITY_PREFIX,
		     XATTR_SECURITY_PREFIX_LEN))
		return false;
	/*
	 * Check for "trusted."
	 */
	if ((ea->namelen >= XATTR_TRUSTED_PREFIX_LEN) &&
	    !strncmp(ea->name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN))
		return false;
	/*
	 * Add any other valid namespace prefixes here
	 */

	/*
	 * We assume it's OS/2's flat namespace
	 */
	return true;
}

static inline int name_size(struct jfs_ea *ea)
{
	if (is_os2_xattr(ea))
		return ea->namelen + XATTR_OS2_PREFIX_LEN;
	else
		return ea->namelen;
}

static inline int copy_name(char *buffer, struct jfs_ea *ea)
{
	int len = ea->namelen;

	if (is_os2_xattr(ea)) {
		memcpy(buffer, XATTR_OS2_PREFIX, XATTR_OS2_PREFIX_LEN);
		buffer += XATTR_OS2_PREFIX_LEN;
		len += XATTR_OS2_PREFIX_LEN;
	}
	memcpy(buffer, ea->name, ea->namelen);
	buffer[ea->namelen] = 0;

	return len;
}

/* Forward references */
static void ea_release(struct inode *inode, struct ea_buffer *ea_buf);

/*
 * NAME: ea_write_inline
 *
 * FUNCTION: Attempt to write an EA inline if area is available
 *
 * PRE CONDITIONS:
 *	Already verified that the specified EA is small enough to fit inline
 *
 * PARAMETERS:
 *	ip	- Inode pointer
 *	ealist	- EA list pointer
 *	size	- size of ealist in bytes
 *	ea	- dxd_t structure to be filled in with necessary EA information
 *		  if we successfully copy the EA inline
 *
 * NOTES:
 *	Checks if the inode's inline area is available.  If so, copies EA inline
 *	and sets <ea> fields appropriately.  Otherwise, returns failure, EA will
 *	have to be put into an extent.
 *
 * RETURNS: 0 for successful copy to inline area; -1 if area not available
 */
static int ea_write_inlin