--- /dev/null
+/*
+ * 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);
+ 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;
+
+ kfree(ui->data);
+ 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_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[sizeof(XATTR_TRUSTED_PREFIX) - 1] == '\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[sizeof(XATTR_SECURITY_PREFIX) - 1] == '\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(mutex_is_locked(&host->i_mutex));
+
+ 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);
+
+ 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:
+ 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(mutex_is_locked(&host->i_mutex));
+
+ 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 size_t security_listxattr(struct dentry *d, char *list, size_t list_size,
+ const char *name, size_t name_len, int flags)
+{
+ const int prefix_len = XATTR_SECURITY_PREFIX_LEN;
+ const size_t total_len = prefix_len + name_len + 1;
+
+ if (list && total_len <= list_size) {
+ memcpy(list, XATTR_SECURITY_PREFIX, prefix_len);
+ memcpy(list + prefix_len, name, name_len);
+ list[prefix_len + name_len] = '\0';
+ }
+
+ return total_len;
+}
+
+static int security_getxattr(struct dentry *d, const char *name, void *buffer,
+ size_t size, int flags)
+{
+ return ubifs_getxattr(d, name, buffer, size);
+}
+
+static int security_setxattr(struct dentry *d, const char *name,
+ const void *value, size_t size, int flags,
+ int handler_flags)
+{
+ return ubifs_setxattr(d, name, value, size, flags);
+}
+
+static const struct xattr_handler ubifs_xattr_security_handler = {
+ .prefix = XATTR_SECURITY_PREFIX,
+ .list = security_listxattr,
+ .get = security_getxattr,
+ .set = security_setxattr,
+};
+
+const struct xattr_handler *ubifs_xattr_handlers[] = {
+ &ubifs_xattr_security_handler,
+ NULL,
+};
+
+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;
+
+ mutex_lock(&inode->i_mutex);
+ err = security_inode_init_security(inode, dentry, qstr,
+ &init_xattrs, 0);
+ mutex_unlock(&inode->i_mutex);
+
+ 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;
+}
Code Review / kvmfornfv.git / blobdiff