[linux-2.6-block.git] / fs / ubifs / xattr.c

/*
 * This file is part of UBIFS.
 *
 * Copyright (C) 2006-2008 Nokia Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 *
 * 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., 51
 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 *
 * Authors: Artem Bityutskiy (Битюцкий Артём)
 *          Adrian Hunter
 */

/*
 * This file implements UBIFS extended attributes support.
 *
 * Extended attributes are implemented as regular inodes with attached data,
 * which limits extended attribute size to UBIFS block size (4KiB). Names of
 * extended attributes are described by extended attribute entries (xentries),
 * which are almost identical to directory entries, but have different key type.
 *
 * In other words, the situation with extended attributes is very similar to
 * directories. Indeed, any inode (but of course not xattr inodes) may have a
 * number of associated xentries, just like directory inodes have associated
 * directory entries. Extended attribute entries store the name of the extended
 * attribute, the host inode number, and the extended attribute inode number.
 * Similarly, direntries store the name, the parent and the target inode
 * numbers. Thus, most of the common UBIFS mechanisms may be re-used for
 * extended attributes.
 *
 * The number of extended attributes is not limited, but there is Linux
 * limitation on the maximum possible size of the list of all extended
 * attributes associated with an inode (%XATTR_LIST_MAX), so UBIFS makes sure
 * the sum of all extended attribute names of the inode does not exceed that
 * limit.
 *
 * Extended attributes are synchronous, which means they are written to the
 * flash media synchronously and there is no write-back for extended attribute
 * inodes. The extended attribute values are not stored in compressed form on
 * the media.
 *
 * Since extended attributes are represented by regular inodes, they are cached
 * in the VFS inode cache. The xentries are cached in the LNC cache (see
 * tnc.c).
 *
 * ACL support is not implemented.
 */

#include "ubifs.h"
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/xattr.h>
#include <linux/posix_acl_xattr.h>

/*
 * Limit the number of extended attributes per inode so that the total size
 * (@xattr_size) is guaranteeded to fit in an 'unsigned int'.
 */
#define MAX_XATTRS_PER_INODE 65535

/*
 * Extended attribute type constants.
 *
 * USER_XATTR: user extended attribute ("user.*")
 * TRUSTED_XATTR: trusted extended attribute ("trusted.*)
 * SECURITY_XATTR: security extended attribute ("security.*")
 */
enum {
	USER_XATTR,
	TRUSTED_XATTR,
	SECURITY_XATTR,
};

static const struct inode_operations empty_iops;
static const struct file_operations empty_fops;

/**
 * create_xattr - create an extended attribute.
 * @c: UBIFS file-system description object
 * @host: host inode
 * @nm: extended attribute name
 * @value: extended attribute value
 * @size: size of extended attribute value
 *
 * This is a helper function which creates an extended attribute of name @nm
 * and value @value for inode @host. The host inode is also updated on flash
 * because the ctime and extended attribute accounting data changes. This
 * function returns zero in case of success and a negative error code in case
 * of failure.
 */
static int create_xattr(struct ubifs_info *c, struct inode *host,
			const struct qstr *nm, const void *value, int size)
{
	int err, names_len;
	struct inode *inode;
	struct ubifs_inode *ui, *host_ui = ubifs_inode(host);
	struct ubifs_budget_req req = { .new_ino = 1, .new_dent = 1,
				.new_ino_d = ALIGN(size, 8), .dirtied_ino = 1,
				.dirtied_ino_d = ALIGN(host_ui->data_len, 8) };

	if (host_ui->xattr_cnt >= MAX_XATTRS_PER_INODE) {
		ubifs_err(c, "inode %lu already has too many xattrs (%d), cannot create more",
			  host->i_ino, host_ui->xattr_cnt);
		return -ENOSPC;
	}
	/*
	 * Linux limits the maximum size of the extended attribute names list
	 * to %XATTR_LIST_MAX. This means we should not allow creating more
	 * extended attributes if the name list becomes larger. This limitation
	 * is artificial for UBIFS, though.
	 */
	names_len = host_ui->xattr_names + host_ui->xattr_cnt + nm->len + 1;
	if (names_len > XATTR_LIST_MAX) {
		ubifs_err(c, "cannot add one more xattr name to inode %lu, total names length would become %d, max. is %d",
			  host->i_ino, names_len, XATTR_LIST_MAX);
		return -ENOSPC;
	}

	err = ubifs_budget_space(c, &req);
	if (err)
		return err;

	inode = ubifs_new_inode(c, host, S_IFREG | S_IRWXUGO);
	if (IS_ERR(inode)) {
		err = PTR_ERR(inode);
		goto out_budg;
	}

	/* Re-define all operations to be "nothing" */
	inode->i_mapping->a_ops = &empty_aops;
	inode->i_op = &empty_iops;
	inode->i_fop = &empty_fops;

	inode->i_flags |= S_SYNC | S_NOATIME | S_NOCMTIME | S_NOQUOTA;
	ui = ubifs_inode(inode);
	ui->xattr = 1;
	ui->flags |= UBIFS_XATTR_FL;
	ui->data = kmemdup(value, size, GFP_NOFS);
	if (!ui->data) {
		err = -ENOMEM;
		goto out_free;
	}
	inode->i_size = ui->ui_size = size;
	ui->data_len = size;

	mutex_lock(&host_ui->ui_mutex);
	host->i_ctime = ubifs_current_time(host);
	host_ui->xattr_cnt += 1;
	host_ui->xattr_size += CALC_DENT_SIZE(nm->len);
	host_ui->xattr_size += CALC_XATTR_BYTES(size);
	host_ui->xattr_names += nm->len;

	err = ubifs_jnl_update(c, host, nm, inode, 0, 1);
	if (err)
		goto out_cancel;
	mutex_unlock(&host_ui->ui_mutex);

	ubifs_release_budget(c, &req);
	insert_inode_hash(inode);
	iput(inode);
	return 0;

out_cancel:
	host_ui->xattr_cnt -= 1;
	host_ui->xattr_size -= CALC_DENT_SIZE(nm->len);
	host_ui->xattr_size -= CALC_XATTR_BYTES(size);
	mutex_unlock(&host_ui->ui_mutex);
out_free:
	make_bad_inode(inode);
	iput(inode);
out_budg:
	ubifs_release_budget(c, &req);
	return err;
}

/**
 * change_xattr - change an extended attribute.
 * @c: UBIFS file-system description object
 * @host: host inode
 * @inode: extended attribute inode
 * @value: extended attribute value
 * @size: size of extended attribute value
 *
 * This helper function changes the value of extended attribute @inode with new
 * data from @value. Returns zero in case of success and a negative error code
 * in case of failure.
 */
static int change_xattr(struct ubifs_info *c, struct inode *host,
			struct inode *inode, const void *value, int size)
{
	int err;
	struct ubifs_inode *host_ui = ubifs_inode(host);
	struct ubifs_inode *ui = ubifs_inode(inode);
	void *buf = NULL;
	struct ubifs_budget_req req = { .dirtied_ino = 2,
		.dirtied_ino_d = ALIGN(size, 8) + ALIGN(host_ui->data_len, 8) };

	ubifs_assert(ui->data_len == inode->i_size);
	err = ubifs_budget_space(c, &req);
	if (err)
		return err;

	buf = kmemdup(value, size, GFP_NOFS);
	if (!buf) {
		err = -ENOMEM;
		goto out_free;
	}
	mutex_lock(&ui->ui_mutex);
	kfree(ui->data);
	ui->data = buf;
	inode->i_size = ui->ui_size = size;
	ui->data_len = size;
	mutex_unlock(&ui->ui_mutex);

	mutex_lock(&host_ui->ui_mutex);
	host->i_ctime = ubifs_current_time(host);
	host_ui->xattr_size -= CALC_XATTR_BYTES(ui->data_len);
	host_ui->xattr_size += CALC_XATTR_BYTES(size);

	/*
	 * It is important to write the host inode after the xattr inode
	 * because if the host inode gets synchronized (via 'fsync()'), then
	 * the extended attribute inode gets synchronized, because it goes
	 * before the host inode in the write-buffer.
	 */
	err = ubifs_jnl_change_xattr(c, inode, host);
	if (err)
		goto out_cancel;
	mutex_unlock(&host_ui->ui_mutex);

	ubifs_release_budget(c, &req);
	return 0;

out_cancel:
	host_ui->xattr_size -= CALC_XATTR_BYTES(size);
	host_ui->xattr_size += CALC_XATTR_BYTES(ui->data_len);
	mutex_unlock(&host_ui->ui_mutex);
	make_bad_inode(inode);
out_free:
	ubifs_release_budget(c, &req);
	return err;
}

/**
 * check_namespace - check extended attribute name-space.
 * @nm: extended attribute name
 *
 * This function makes sure the extended attribute name belongs to one of the
 * supported extended attribute name-spaces. Returns name-space index in case
 * of success and a negative error code in case of failure.
 */
static int check_namespace(const struct qstr *nm)
{
	int type;

	if (nm->len > UBIFS_MAX_NLEN)
		return -ENAMETOOLONG;

	if (!strncmp(nm->name, XATTR_TRUSTED_PREFIX,
		     XATTR_TRUSTED_PREFIX_LEN)) {
		if (nm->name[XATTR_TRUSTED_PREFIX_LEN] == '\0')
			return -EINVAL;
		type = TRUSTED_XATTR;
	} else if (!strncmp(nm->name, XATTR_USER_PREFIX,
				      XATTR_USER_PREFIX_LEN)) {
		if (nm->name[XATTR_USER_PREFIX_LEN] == '\0')
			return -EINVAL;
		type = USER_XATTR;
	} else if (!strncmp(nm->name, XATTR_SECURITY_PREFIX,
				     XATTR_SECURITY_PREFIX_LEN)) {
		if (nm->name[XATTR_SECURITY_PREFIX_LEN] == '\0')
			return -EINVAL;
		type = SECURITY_XATTR;
	} else
		return -EOPNOTSUPP;

	return type;
}

static struct inode *iget_xattr(struct ubifs_info *c, ino_t inum)
{
	struct inode *inode;

	inode = ubifs_iget(c->vfs_sb, inum);
	if (IS_ERR(inode)) {
		ubifs_err(c, "dead extended attribute entry, error %d",
			  (int)PTR_ERR(inode));
		return inode;
	}
	if (ubifs_inode(inode)->xattr)
		return inode;
	ubifs_err(c, "corrupt extended attribute entry");
	iput(inode);
	return ERR_PTR(-EINVAL);
}

static int setxattr(struct inode *host, const char *name, const void *value,
		    size_t size, int flags)
{
	struct inode *inode;
	struct ubifs_info *c = host->i_sb->s_fs_info;
	struct qstr nm = QSTR_INIT(name, strlen(name));
	struct ubifs_dent_node *xent;
	union ubifs_key key;
	int err, type;

	ubifs_assert(inode_is_locked(host));

	if (size > UBIFS_MAX_INO_DATA)
		return -ERANGE;

	type = check_namespace(&nm);
	if (type < 0)
		return type;

	xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
	if (!xent)
		return -ENOMEM;

	/*
	 * The extended attribute entries are stored in LNC, so multiple
	 * look-ups do not involve reading the flash.
	 */
	xent_key_init(c, &key, host->i_ino, &nm);
	err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
	if (err) {
		if (err != -ENOENT)
			goto out_free;

		if (flags & XATTR_REPLACE)
			/* We are asked not to create the xattr */
			err = -ENODATA;
		else
			err = create_xattr(c, host, &nm, value, size);
		goto out_free;
	}

	if (flags & XATTR_CREATE) {
		/* We are asked not to replace the xattr */
		err = -EEXIST;
		goto out_free;
	}

	inode = iget_xattr(c, le64_to_cpu(xent->inum));
	if (IS_ERR(inode)) {
		err = PTR_ERR(inode);
		goto out_free;
	}

	err = change_xattr(c, host, inode, value, size);
	iput(inode);

out_free:
	kfree(xent);
	return err;
}

int ubifs_setxattr(struct dentry *dentry, const char *name,
		   const void *value, size_t size, int flags)
{
	dbg_gen("xattr '%s', host ino %lu ('%pd'), size %zd",
		name, d_inode(dentry)->i_ino, dentry, size);

	return setxattr(d_inode(dentry), name, value, size, flags);
}

ssize_t ubifs_getxattr(struct dentry *dentry, const char *name, void *buf,
		       size_t size)
{
	struct inode *inode, *host = d_inode(dentry);
	struct ubifs_info *c = host->i_sb->s_fs_info;
	struct qstr nm = QSTR_INIT(name, strlen(name));
	struct ubifs_inode *ui;
	struct ubifs_dent_node *xent;
	union ubifs_key key;
	int err;

	dbg_gen("xattr '%s', ino %lu ('%pd'), buf size %zd", name,
		host->i_ino, dentry, size);

	err = check_namespace(&nm);
	if (err < 0)
		return err;

	xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
	if (!xent)
		return -ENOMEM;

	xent_key_init(c, &key, host->i_ino, &nm);
	err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
	if (err) {
		if (err == -ENOENT)
			err = -ENODATA;
		goto out_unlock;
	}

	inode = iget_xattr(c, le64_to_cpu(xent->inum));
	if (IS_ERR(inode)) {
		err = PTR_ERR(inode);
		goto out_unlock;
	}

	ui = ubifs_inode(inode);
	ubifs_assert(inode->i_size == ui->data_len);
	ubifs_assert(ubifs_inode(host)->xattr_size > ui->data_len);

	mutex_lock(&ui->ui_mutex);
	if (buf) {
		/* If @buf is %NULL we are supposed to return the length */
		if (ui->data_len > size) {
			ubifs_err(c, "buffer size %zd, xattr len %d",
				  size, ui->data_len);
			err = -ERANGE;
			goto out_iput;
		}

		memcpy(buf, ui->data, ui->data_len);
	}
	err = ui->data_len;

out_iput:
	mutex_unlock(&ui->ui_mutex);
	iput(inode);
out_unlock:
	kfree(xent);
	return err;
}

ssize_t ubifs_listxattr(struct dentry *dentry, char *buffer, size_t size)
{
	union ubifs_key key;
	struct inode *host = d_inode(dentry);
	struct ubifs_info *c = host->i_sb->s_fs_info;
	struct ubifs_inode *host_ui = ubifs_inode(host);
	struct ubifs_dent_node *xent, *pxent = NULL;
	int err, len, written = 0;
	struct qstr nm = { .name = NULL };

	dbg_gen("ino %lu ('%pd'), buffer size %zd", host->i_ino,
		dentry, size);

	len = host_ui->xattr_names + host_ui->xattr_cnt;
	if (!buffer)
		/*
		 * We should return the minimum buffer size which will fit a
		 * null-terminated list of all the extended attribute names.
		 */
		return len;

	if (len > size)
		return -ERANGE;

	lowest_xent_key(c, &key, host->i_ino);
	while (1) {
		int type;

		xent = ubifs_tnc_next_ent(c, &key, &nm);
		if (IS_ERR(xent)) {
			err = PTR_ERR(xent);
			break;
		}

		nm.name = xent->name;
		nm.len = le16_to_cpu(xent->nlen);

		type = check_namespace(&nm);
		if (unlikely(type < 0)) {
			err = type;
			break;
		}

		/* Show trusted namespace only for "power" users */
		if (type != TRUSTED_XATTR || capable(CAP_SYS_ADMIN)) {
			memcpy(buffer + written, nm.name, nm.len + 1);
			written += nm.len + 1;
		}

		kfree(pxent);
		pxent = xent;
		key_read(c, &xent->key, &key);
	}

	kfree(pxent);
	if (err != -ENOENT) {
		ubifs_err(c, "cannot find next direntry, error %d", err);
		return err;
	}

	ubifs_assert(written <= size);
	return written;
}

static int remove_xattr(struct ubifs_info *c, struct inode *host,
			struct inode *inode, const struct qstr *nm)
{
	int err;
	struct ubifs_inode *host_ui = ubifs_inode(host);
	struct ubifs_inode *ui = ubifs_inode(inode);
	struct ubifs_budget_req req = { .dirtied_ino = 2, .mod_dent = 1,
				.dirtied_ino_d = ALIGN(host_ui->data_len, 8) };

	ubifs_assert(ui->data_len == inode->i_size);

	err = ubifs_budget_space(c, &req);
	if (err)
		return err;

	mutex_lock(&host_ui->ui_mutex);
	host->i_ctime = ubifs_current_time(host);
	host_ui->xattr_cnt -= 1;
	host_ui->xattr_size -= CALC_DENT_SIZE(nm->len);
	host_ui->xattr_size -= CALC_XATTR_BYTES(ui->data_len);
	host_ui->xattr_names -= nm->len;

	err = ubifs_jnl_delete_xattr(c, host, inode, nm);
	if (err)
		goto out_cancel;
	mutex_unlock(&host_ui->ui_mutex);

	ubifs_release_budget(c, &req);
	return 0;

out_cancel:
	host_ui->xattr_cnt += 1;
	host_ui->xattr_size += CALC_DENT_SIZE(nm->len);
	host_ui->xattr_size += CALC_XATTR_BYTES(ui->data_len);
	mutex_unlock(&host_ui->ui_mutex);
	ubifs_release_budget(c, &req);
	make_bad_inode(inode);
	return err;
}

int ubifs_removexattr(struct dentry *dentry, const char *name)
{
	struct inode *inode, *host = d_inode(dentry);
	struct ubifs_info *c = host->i_sb->s_fs_info;
	struct qstr nm = QSTR_INIT(name, strlen(name));
	struct ubifs_dent_node *xent;
	union ubifs_key key;
	int err;

	dbg_gen("xattr '%s', ino %lu ('%pd')", name,
		host->i_ino, dentry);
	ubifs_assert(inode_is_locked(host));

	err = check_namespace(&nm);
	if (err < 0)
		return err;

	xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
	if (!xent)
		return -ENOMEM;

	xent_key_init(c, &key, host->i_ino, &nm);
	err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
	if (err) {
		if (err == -ENOENT)
			err = -ENODATA;
		goto out_free;
	}

	inode = iget_xattr(c, le64_to_cpu(xent->inum));
	if (IS_ERR(inode)) {
		err = PTR_ERR(inode);
		goto out_free;
	}

	ubifs_assert(inode->i_nlink == 1);
	clear_nlink(inode);
	err = remove_xattr(c, host, inode, &nm);
	if (err)
		set_nlink(inode, 1);

	/* If @i_nlink is 0, 'iput()' will delete the inode */
	iput(inode);

out_free:
	kfree(xent);
	return err;
}

static int init_xattrs(struct inode *inode, const struct xattr *xattr_array,
		      void *fs_info)
{
	const struct xattr *xattr;
	char *name;
	int err = 0;

	for (xattr = xattr_array; xattr->name != NULL; xattr++) {
		name = kmalloc(XATTR_SECURITY_PREFIX_LEN +
			       strlen(xattr->name) + 1, GFP_NOFS);
		if (!name) {
			err = -ENOMEM;
			break;
		}
		strcpy(name, XATTR_SECURITY_PREFIX);
		strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name);
		err = setxattr(inode, name, xattr->value, xattr->value_len, 0);
		kfree(name);
		if (err < 0)
			break;
	}

	return err;
}

int ubifs_init_security(struct inode *dentry, struct inode *inode,
			const struct qstr *qstr)
{
	int err;

	err = security_inode_init_security(inode, dentry, qstr,
					   &init_xattrs, 0);
	if (err) {
		struct ubifs_info *c = dentry->i_sb->s_fs_info;
		ubifs_err(c, "cannot initialize security for inode %lu, error %d",
			  inode->i_ino, err);
	}
	return err;
}
Commit	Line	Data
1e51764a AB	1	/*
	2	* This file is part of UBIFS.
	3	*
	4	* Copyright (C) 2006-2008 Nokia Corporation.
	5	*
	6	* This program is free software; you can redistribute it and/or modify it
	7	* under the terms of the GNU General Public License version 2 as published by
	8	* the Free Software Foundation.
	9	*
	10	* This program is distributed in the hope that it will be useful, but WITHOUT
	11	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	12	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
	13	* more details.
	14	*
	15	* You should have received a copy of the GNU General Public License along with
	16	* this program; if not, write to the Free Software Foundation, Inc., 51
	17	* Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
	18	*
	19	* Authors: Artem Bityutskiy (Битюцкий Артём)
	20	* Adrian Hunter
	21	*/
	22
	23	/*
	24	* This file implements UBIFS extended attributes support.
	25	*
	26	* Extended attributes are implemented as regular inodes with attached data,
	27	* which limits extended attribute size to UBIFS block size (4KiB). Names of
	28	* extended attributes are described by extended attribute entries (xentries),
	29	* which are almost identical to directory entries, but have different key type.
	30	*
	31	* In other words, the situation with extended attributes is very similar to
	32	* directories. Indeed, any inode (but of course not xattr inodes) may have a
	33	* number of associated xentries, just like directory inodes have associated
	34	* directory entries. Extended attribute entries store the name of the extended
	35	* attribute, the host inode number, and the extended attribute inode number.
	36	* Similarly, direntries store the name, the parent and the target inode
	37	* numbers. Thus, most of the common UBIFS mechanisms may be re-used for
	38	* extended attributes.
	39	*
	40	* The number of extended attributes is not limited, but there is Linux
	41	* limitation on the maximum possible size of the list of all extended
	42	* attributes associated with an inode (%XATTR_LIST_MAX), so UBIFS makes sure
	43	* the sum of all extended attribute names of the inode does not exceed that
	44	* limit.
	45	*
	46	* Extended attributes are synchronous, which means they are written to the
	47	* flash media synchronously and there is no write-back for extended attribute
	48	* inodes. The extended attribute values are not stored in compressed form on
	49	* the media.
	50	*
	51	* Since extended attributes are represented by regular inodes, they are cached
	52	* in the VFS inode cache. The xentries are cached in the LNC cache (see
	53	* tnc.c).
	54	*
	55	* ACL support is not implemented.
	56	*/
	57
073aaa1b	58	#include "ubifs.h"
7dcda1c9	59	#include <linux/fs.h>
5a0e3ad6	60	#include <linux/slab.h>
1e51764a AB	61	#include <linux/xattr.h>
1e51764a AB	62	#include <linux/posix_acl_xattr.h>
1e51764a AB	63
	64	/*
	65	* Limit the number of extended attributes per inode so that the total size
c78c7e35	66	* (@xattr_size) is guaranteeded to fit in an 'unsigned int'.
1e51764a AB	67	*/
	68	#define MAX_XATTRS_PER_INODE 65535
	69
	70	/*
	71	* Extended attribute type constants.
	72	*
	73	* USER_XATTR: user extended attribute ("user.*")
	74	* TRUSTED_XATTR: trusted extended attribute ("trusted.*)
	75	* SECURITY_XATTR: security extended attribute ("security.*")
	76	*/
	77	enum {
	78	USER_XATTR,
	79	TRUSTED_XATTR,
	80	SECURITY_XATTR,
	81	};
	82
14ffd5d0 SD	83	static const struct inode_operations empty_iops;
14ffd5d0 SD	84	static const struct file_operations empty_fops;
1e51764a AB	85
	86	/**
	87	* create_xattr - create an extended attribute.
	88	* @c: UBIFS file-system description object
	89	* @host: host inode
	90	* @nm: extended attribute name
	91	* @value: extended attribute value
	92	* @size: size of extended attribute value
	93	*
	94	* This is a helper function which creates an extended attribute of name @nm
	95	* and value @value for inode @host. The host inode is also updated on flash
	96	* because the ctime and extended attribute accounting data changes. This
	97	* function returns zero in case of success and a negative error code in case
	98	* of failure.
	99	*/
	100	static int create_xattr(struct ubifs_info c, struct inode host,
	101	const struct qstr nm, const void value, int size)
	102	{
fee1756d	103	int err, names_len;
1e51764a AB	104	struct inode *inode;
	105	struct ubifs_inode ui, host_ui = ubifs_inode(host);
	106	struct ubifs_budget_req req = { .new_ino = 1, .new_dent = 1,
5acd6ff8 ZS	107	.new_ino_d = ALIGN(size, 8), .dirtied_ino = 1,
5acd6ff8 ZS	108	.dirtied_ino_d = ALIGN(host_ui->data_len, 8) };
1e51764a	109
fee1756d	110	if (host_ui->xattr_cnt >= MAX_XATTRS_PER_INODE) {
235c362b	111	ubifs_err(c, "inode %lu already has too many xattrs (%d), cannot create more",
fee1756d	112	host->i_ino, host_ui->xattr_cnt);
1e51764a	113	return -ENOSPC;
fee1756d	114	}
1e51764a AB	115	/*
1e51764a AB	116	* Linux limits the maximum size of the extended attribute names list
c78c7e35	117	* to %XATTR_LIST_MAX. This means we should not allow creating more
1e51764a AB	118	* extended attributes if the name list becomes larger. This limitation
	119	* is artificial for UBIFS, though.
	120	*/
fee1756d SN	121	names_len = host_ui->xattr_names + host_ui->xattr_cnt + nm->len + 1;
fee1756d SN	122	if (names_len > XATTR_LIST_MAX) {
235c362b	123	ubifs_err(c, "cannot add one more xattr name to inode %lu, total names length would become %d, max. is %d",
fee1756d	124	host->i_ino, names_len, XATTR_LIST_MAX);
1e51764a	125	return -ENOSPC;
fee1756d	126	}
1e51764a AB	127
	128	err = ubifs_budget_space(c, &req);
	129	if (err)
	130	return err;
	131
	132	inode = ubifs_new_inode(c, host, S_IFREG \| S_IRWXUGO);
	133	if (IS_ERR(inode)) {
	134	err = PTR_ERR(inode);
	135	goto out_budg;
	136	}
	137
1e51764a	138	/* Re-define all operations to be "nothing" */
7dcda1c9	139	inode->i_mapping->a_ops = &empty_aops;
14ffd5d0 SD	140	inode->i_op = &empty_iops;
14ffd5d0 SD	141	inode->i_fop = &empty_fops;
1e51764a AB	142
	143	inode->i_flags \|= S_SYNC \| S_NOATIME \| S_NOCMTIME \| S_NOQUOTA;
	144	ui = ubifs_inode(inode);
	145	ui->xattr = 1;
	146	ui->flags \|= UBIFS_XATTR_FL;
eaecf43a	147	ui->data = kmemdup(value, size, GFP_NOFS);
1e51764a AB	148	if (!ui->data) {
1e51764a AB	149	err = -ENOMEM;
c78c7e35	150	goto out_free;
1e51764a	151	}
c78c7e35 AB	152	inode->i_size = ui->ui_size = size;
	153	ui->data_len = size;
	154
	155	mutex_lock(&host_ui->ui_mutex);
1e51764a AB	156	host->i_ctime = ubifs_current_time(host);
	157	host_ui->xattr_cnt += 1;
	158	host_ui->xattr_size += CALC_DENT_SIZE(nm->len);
	159	host_ui->xattr_size += CALC_XATTR_BYTES(size);
	160	host_ui->xattr_names += nm->len;
	161
1e51764a AB	162	err = ubifs_jnl_update(c, host, nm, inode, 0, 1);
	163	if (err)
	164	goto out_cancel;
	165	mutex_unlock(&host_ui->ui_mutex);
	166
	167	ubifs_release_budget(c, &req);
	168	insert_inode_hash(inode);
	169	iput(inode);
	170	return 0;
	171
	172	out_cancel:
	173	host_ui->xattr_cnt -= 1;
	174	host_ui->xattr_size -= CALC_DENT_SIZE(nm->len);
	175	host_ui->xattr_size -= CALC_XATTR_BYTES(size);
1e51764a	176	mutex_unlock(&host_ui->ui_mutex);
c78c7e35	177	out_free:
1e51764a AB	178	make_bad_inode(inode);
	179	iput(inode);
	180	out_budg:
	181	ubifs_release_budget(c, &req);
	182	return err;
	183	}
	184
	185	/**
	186	* change_xattr - change an extended attribute.
	187	* @c: UBIFS file-system description object
	188	* @host: host inode
	189	* @inode: extended attribute inode
	190	* @value: extended attribute value
	191	* @size: size of extended attribute value
	192	*
	193	* This helper function changes the value of extended attribute @inode with new
	194	* data from @value. Returns zero in case of success and a negative error code
	195	* in case of failure.
	196	*/
	197	static int change_xattr(struct ubifs_info c, struct inode host,
	198	struct inode inode, const void value, int size)
	199	{
	200	int err;
	201	struct ubifs_inode *host_ui = ubifs_inode(host);
	202	struct ubifs_inode *ui = ubifs_inode(inode);
ab92a20b	203	void *buf = NULL;
1e51764a	204	struct ubifs_budget_req req = { .dirtied_ino = 2,
5acd6ff8	205	.dirtied_ino_d = ALIGN(size, 8) + ALIGN(host_ui->data_len, 8) };
1e51764a AB	206
	207	ubifs_assert(ui->data_len == inode->i_size);
	208	err = ubifs_budget_space(c, &req);
	209	if (err)
	210	return err;
	211
ab92a20b DY	212	buf = kmemdup(value, size, GFP_NOFS);
ab92a20b DY	213	if (!buf) {
1e51764a	214	err = -ENOMEM;
c78c7e35	215	goto out_free;
1e51764a	216	}
ab92a20b DY	217	mutex_lock(&ui->ui_mutex);
	218	kfree(ui->data);
	219	ui->data = buf;
1e51764a AB	220	inode->i_size = ui->ui_size = size;
1e51764a AB	221	ui->data_len = size;
ab92a20b	222	mutex_unlock(&ui->ui_mutex);
1e51764a	223
c78c7e35 AB	224	mutex_lock(&host_ui->ui_mutex);
	225	host->i_ctime = ubifs_current_time(host);
	226	host_ui->xattr_size -= CALC_XATTR_BYTES(ui->data_len);
	227	host_ui->xattr_size += CALC_XATTR_BYTES(size);
	228
1e51764a AB	229	/*
	230	* It is important to write the host inode after the xattr inode
	231	* because if the host inode gets synchronized (via 'fsync()'), then
	232	* the extended attribute inode gets synchronized, because it goes
	233	* before the host inode in the write-buffer.
	234	*/
	235	err = ubifs_jnl_change_xattr(c, inode, host);
	236	if (err)
	237	goto out_cancel;
	238	mutex_unlock(&host_ui->ui_mutex);
	239
	240	ubifs_release_budget(c, &req);
	241	return 0;
	242
	243	out_cancel:
	244	host_ui->xattr_size -= CALC_XATTR_BYTES(size);
	245	host_ui->xattr_size += CALC_XATTR_BYTES(ui->data_len);
1e51764a	246	mutex_unlock(&host_ui->ui_mutex);
c78c7e35 AB	247	make_bad_inode(inode);
c78c7e35 AB	248	out_free:
1e51764a AB	249	ubifs_release_budget(c, &req);
	250	return err;
	251	}
	252
	253	/**
	254	* check_namespace - check extended attribute name-space.
	255	* @nm: extended attribute name
	256	*
	257	* This function makes sure the extended attribute name belongs to one of the
	258	* supported extended attribute name-spaces. Returns name-space index in case
	259	* of success and a negative error code in case of failure.
	260	*/
	261	static int check_namespace(const struct qstr *nm)
	262	{
	263	int type;
	264
	265	if (nm->len > UBIFS_MAX_NLEN)
	266	return -ENAMETOOLONG;
	267
	268	if (!strncmp(nm->name, XATTR_TRUSTED_PREFIX,
	269	XATTR_TRUSTED_PREFIX_LEN)) {
4fdd1d51	270	if (nm->name[XATTR_TRUSTED_PREFIX_LEN] == '\0')
1e51764a AB	271	return -EINVAL;
	272	type = TRUSTED_XATTR;
	273	} else if (!strncmp(nm->name, XATTR_USER_PREFIX,
	274	XATTR_USER_PREFIX_LEN)) {
	275	if (nm->name[XATTR_USER_PREFIX_LEN] == '\0')
	276	return -EINVAL;
	277	type = USER_XATTR;
	278	} else if (!strncmp(nm->name, XATTR_SECURITY_PREFIX,
	279	XATTR_SECURITY_PREFIX_LEN)) {
4fdd1d51	280	if (nm->name[XATTR_SECURITY_PREFIX_LEN] == '\0')
1e51764a AB	281	return -EINVAL;
	282	type = SECURITY_XATTR;
	283	} else
	284	return -EOPNOTSUPP;
	285
	286	return type;
	287	}
	288
	289	static struct inode iget_xattr(struct ubifs_info c, ino_t inum)
	290	{
	291	struct inode *inode;
	292
	293	inode = ubifs_iget(c->vfs_sb, inum);
	294	if (IS_ERR(inode)) {
235c362b	295	ubifs_err(c, "dead extended attribute entry, error %d",
1e51764a AB	296	(int)PTR_ERR(inode));
	297	return inode;
	298	}
	299	if (ubifs_inode(inode)->xattr)
	300	return inode;
235c362b	301	ubifs_err(c, "corrupt extended attribute entry");
1e51764a AB	302	iput(inode);
	303	return ERR_PTR(-EINVAL);
	304	}
	305
895d9db2 SN	306	static int setxattr(struct inode host, const char name, const void *value,
895d9db2 SN	307	size_t size, int flags)
1e51764a	308	{
895d9db2	309	struct inode *inode;
1e51764a	310	struct ubifs_info *c = host->i_sb->s_fs_info;
26fe5750	311	struct qstr nm = QSTR_INIT(name, strlen(name));
1e51764a AB	312	struct ubifs_dent_node *xent;
	313	union ubifs_key key;
	314	int err, type;
	315
5955102c	316	ubifs_assert(inode_is_locked(host));
1e51764a AB	317
	318	if (size > UBIFS_MAX_INO_DATA)
	319	return -ERANGE;
	320
	321	type = check_namespace(&nm);
	322	if (type < 0)
	323	return type;
	324
	325	xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
	326	if (!xent)
	327	return -ENOMEM;
	328
	329	/*
	330	* The extended attribute entries are stored in LNC, so multiple
	331	* look-ups do not involve reading the flash.
	332	*/
	333	xent_key_init(c, &key, host->i_ino, &nm);
	334	err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
	335	if (err) {
	336	if (err != -ENOENT)
	337	goto out_free;
	338
	339	if (flags & XATTR_REPLACE)
	340	/* We are asked not to create the xattr */
	341	err = -ENODATA;
	342	else
	343	err = create_xattr(c, host, &nm, value, size);
	344	goto out_free;
	345	}
	346
	347	if (flags & XATTR_CREATE) {
	348	/* We are asked not to replace the xattr */
	349	err = -EEXIST;
	350	goto out_free;
	351	}
	352
	353	inode = iget_xattr(c, le64_to_cpu(xent->inum));
	354	if (IS_ERR(inode)) {
	355	err = PTR_ERR(inode);
	356	goto out_free;
	357	}
	358
	359	err = change_xattr(c, host, inode, value, size);
	360	iput(inode);
	361
	362	out_free:
	363	kfree(xent);
	364	return err;
	365	}
	366
895d9db2 SN	367	int ubifs_setxattr(struct dentry dentry, const char name,
	368	const void *value, size_t size, int flags)
	369	{
	370	dbg_gen("xattr '%s', host ino %lu ('%pd'), size %zd",
2b0143b5	371	name, d_inode(dentry)->i_ino, dentry, size);
895d9db2	372
2b0143b5	373	return setxattr(d_inode(dentry), name, value, size, flags);
895d9db2 SN	374	}
895d9db2 SN	375
1e51764a AB	376	ssize_t ubifs_getxattr(struct dentry dentry, const char name, void *buf,
	377	size_t size)
	378	{
2b0143b5	379	struct inode inode, host = d_inode(dentry);
1e51764a	380	struct ubifs_info *c = host->i_sb->s_fs_info;
26fe5750	381	struct qstr nm = QSTR_INIT(name, strlen(name));
1e51764a AB	382	struct ubifs_inode *ui;
	383	struct ubifs_dent_node *xent;
	384	union ubifs_key key;
	385	int err;
	386
4cb2a01d AV	387	dbg_gen("xattr '%s', ino %lu ('%pd'), buf size %zd", name,
4cb2a01d AV	388	host->i_ino, dentry, size);
1e51764a AB	389
	390	err = check_namespace(&nm);
	391	if (err < 0)
	392	return err;
	393
	394	xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
	395	if (!xent)
	396	return -ENOMEM;
	397
1e51764a AB	398	xent_key_init(c, &key, host->i_ino, &nm);
	399	err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
	400	if (err) {
	401	if (err == -ENOENT)
	402	err = -ENODATA;
	403	goto out_unlock;
	404	}
	405
	406	inode = iget_xattr(c, le64_to_cpu(xent->inum));
	407	if (IS_ERR(inode)) {
	408	err = PTR_ERR(inode);
	409	goto out_unlock;
	410	}
	411
	412	ui = ubifs_inode(inode);
	413	ubifs_assert(inode->i_size == ui->data_len);
	414	ubifs_assert(ubifs_inode(host)->xattr_size > ui->data_len);
	415
ab92a20b	416	mutex_lock(&ui->ui_mutex);
1e51764a AB	417	if (buf) {
	418	/* If @buf is %NULL we are supposed to return the length */
	419	if (ui->data_len > size) {
235c362b	420	ubifs_err(c, "buffer size %zd, xattr len %d",
a6aae4dd	421	size, ui->data_len);
1e51764a AB	422	err = -ERANGE;
	423	goto out_iput;
	424	}
	425
	426	memcpy(buf, ui->data, ui->data_len);
	427	}
	428	err = ui->data_len;
	429
	430	out_iput:
ab92a20b	431	mutex_unlock(&ui->ui_mutex);
1e51764a AB	432	iput(inode);
1e51764a AB	433	out_unlock:
1e51764a AB	434	kfree(xent);
	435	return err;
	436	}
	437
	438	ssize_t ubifs_listxattr(struct dentry dentry, char buffer, size_t size)
	439	{
	440	union ubifs_key key;
2b0143b5	441	struct inode *host = d_inode(dentry);
1e51764a AB	442	struct ubifs_info *c = host->i_sb->s_fs_info;
	443	struct ubifs_inode *host_ui = ubifs_inode(host);
	444	struct ubifs_dent_node xent, pxent = NULL;
	445	int err, len, written = 0;
	446	struct qstr nm = { .name = NULL };
	447
4cb2a01d AV	448	dbg_gen("ino %lu ('%pd'), buffer size %zd", host->i_ino,
4cb2a01d AV	449	dentry, size);
1e51764a AB	450
	451	len = host_ui->xattr_names + host_ui->xattr_cnt;
	452	if (!buffer)
	453	/*
	454	* We should return the minimum buffer size which will fit a
	455	* null-terminated list of all the extended attribute names.
	456	*/
	457	return len;
	458
	459	if (len > size)
	460	return -ERANGE;
	461
	462	lowest_xent_key(c, &key, host->i_ino);
1e51764a AB	463	while (1) {
	464	int type;
	465
	466	xent = ubifs_tnc_next_ent(c, &key, &nm);
8d47aef4	467	if (IS_ERR(xent)) {
1e51764a AB	468	err = PTR_ERR(xent);
	469	break;
	470	}
	471
	472	nm.name = xent->name;
	473	nm.len = le16_to_cpu(xent->nlen);
	474
	475	type = check_namespace(&nm);
	476	if (unlikely(type < 0)) {
	477	err = type;
	478	break;
	479	}
	480
	481	/* Show trusted namespace only for "power" users */
	482	if (type != TRUSTED_XATTR \|\| capable(CAP_SYS_ADMIN)) {
	483	memcpy(buffer + written, nm.name, nm.len + 1);
	484	written += nm.len + 1;
	485	}
	486
	487	kfree(pxent);
	488	pxent = xent;
	489	key_read(c, &xent->key, &key);
	490	}
1e51764a AB	491
	492	kfree(pxent);
	493	if (err != -ENOENT) {
235c362b	494	ubifs_err(c, "cannot find next direntry, error %d", err);
1e51764a AB	495	return err;
	496	}
	497
	498	ubifs_assert(written <= size);
	499	return written;
	500	}
	501
	502	static int remove_xattr(struct ubifs_info c, struct inode host,
	503	struct inode inode, const struct qstr nm)
	504	{
	505	int err;
	506	struct ubifs_inode *host_ui = ubifs_inode(host);
	507	struct ubifs_inode *ui = ubifs_inode(inode);
5acd6ff8 ZS	508	struct ubifs_budget_req req = { .dirtied_ino = 2, .mod_dent = 1,
5acd6ff8 ZS	509	.dirtied_ino_d = ALIGN(host_ui->data_len, 8) };
1e51764a AB	510
	511	ubifs_assert(ui->data_len == inode->i_size);
	512
	513	err = ubifs_budget_space(c, &req);
	514	if (err)
	515	return err;
	516
	517	mutex_lock(&host_ui->ui_mutex);
	518	host->i_ctime = ubifs_current_time(host);
	519	host_ui->xattr_cnt -= 1;
	520	host_ui->xattr_size -= CALC_DENT_SIZE(nm->len);
	521	host_ui->xattr_size -= CALC_XATTR_BYTES(ui->data_len);
	522	host_ui->xattr_names -= nm->len;
	523
	524	err = ubifs_jnl_delete_xattr(c, host, inode, nm);
	525	if (err)
	526	goto out_cancel;
	527	mutex_unlock(&host_ui->ui_mutex);
	528
	529	ubifs_release_budget(c, &req);
	530	return 0;
	531
	532	out_cancel:
	533	host_ui->xattr_cnt += 1;
	534	host_ui->xattr_size += CALC_DENT_SIZE(nm->len);
	535	host_ui->xattr_size += CALC_XATTR_BYTES(ui->data_len);
	536	mutex_unlock(&host_ui->ui_mutex);
	537	ubifs_release_budget(c, &req);
	538	make_bad_inode(inode);
	539	return err;
	540	}
	541
	542	int ubifs_removexattr(struct dentry dentry, const char name)
	543	{
2b0143b5	544	struct inode inode, host = d_inode(dentry);
1e51764a	545	struct ubifs_info *c = host->i_sb->s_fs_info;
26fe5750	546	struct qstr nm = QSTR_INIT(name, strlen(name));
1e51764a AB	547	struct ubifs_dent_node *xent;
	548	union ubifs_key key;
	549	int err;
	550
4cb2a01d AV	551	dbg_gen("xattr '%s', ino %lu ('%pd')", name,
4cb2a01d AV	552	host->i_ino, dentry);
5955102c	553	ubifs_assert(inode_is_locked(host));
1e51764a AB	554
	555	err = check_namespace(&nm);
	556	if (err < 0)
	557	return err;
	558
	559	xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
	560	if (!xent)
	561	return -ENOMEM;
	562
	563	xent_key_init(c, &key, host->i_ino, &nm);
	564	err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
	565	if (err) {
	566	if (err == -ENOENT)
	567	err = -ENODATA;
	568	goto out_free;
	569	}
	570
	571	inode = iget_xattr(c, le64_to_cpu(xent->inum));
	572	if (IS_ERR(inode)) {
	573	err = PTR_ERR(inode);
	574	goto out_free;
	575	}
	576
	577	ubifs_assert(inode->i_nlink == 1);
6d6b77f1	578	clear_nlink(inode);
1e51764a AB	579	err = remove_xattr(c, host, inode, &nm);
1e51764a AB	580	if (err)
bfe86848	581	set_nlink(inode, 1);
1e51764a AB	582
	583	/* If @i_nlink is 0, 'iput()' will delete the inode */
	584	iput(inode);
	585
	586	out_free:
	587	kfree(xent);
	588	return err;
	589	}
d7f0b70d	590
d7f0b70d SN	591	static int init_xattrs(struct inode inode, const struct xattr xattr_array,
	592	void *fs_info)
	593	{
	594	const struct xattr *xattr;
	595	char *name;
	596	int err = 0;
	597
	598	for (xattr = xattr_array; xattr->name != NULL; xattr++) {
	599	name = kmalloc(XATTR_SECURITY_PREFIX_LEN +
	600	strlen(xattr->name) + 1, GFP_NOFS);
	601	if (!name) {
	602	err = -ENOMEM;
	603	break;
	604	}
	605	strcpy(name, XATTR_SECURITY_PREFIX);
	606	strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name);
	607	err = setxattr(inode, name, xattr->value, xattr->value_len, 0);
	608	kfree(name);
	609	if (err < 0)
	610	break;
	611	}
	612
	613	return err;
	614	}
	615
	616	int ubifs_init_security(struct inode dentry, struct inode inode,
	617	const struct qstr *qstr)
	618	{
	619	int err;
	620
d7f0b70d SN	621	err = security_inode_init_security(inode, dentry, qstr,
d7f0b70d SN	622	&init_xattrs, 0);
235c362b SY	623	if (err) {
	624	struct ubifs_info *c = dentry->i_sb->s_fs_info;
	625	ubifs_err(c, "cannot initialize security for inode %lu, error %d",
fee1756d	626	inode->i_ino, err);
235c362b	627	}
d7f0b70d SN	628	return err;
d7f0b70d SN	629	}