alistair23-linux/fs/jfs/acl.c
Ernesto A. Fernández f070e5ac9b jfs: preserve i_mode if __jfs_set_acl() fails
When changing a file's acl mask, __jfs_set_acl() will first set the group
bits of i_mode to the value of the mask, and only then set the actual
extended attribute representing the new acl.

If the second part fails (due to lack of space, for example) and the file
had no acl attribute to begin with, the system will from now on assume
that the mask permission bits are actual group permission bits, potentially
granting access to the wrong users.

Prevent this by only changing the inode mode after the acl has been set.

Signed-off-by: Ernesto A. Fernández <ernesto.mnd.fernandez@gmail.com>
Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>
2017-07-18 14:28:06 -05:00

162 lines
3.7 KiB
C

/*
* Copyright (C) International Business Machines Corp., 2002-2004
* Copyright (C) Andreas Gruenbacher, 2001
* Copyright (C) Linus Torvalds, 1991, 1992
*
* 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/sched.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/posix_acl_xattr.h>
#include "jfs_incore.h"
#include "jfs_txnmgr.h"
#include "jfs_xattr.h"
#include "jfs_acl.h"
struct posix_acl *jfs_get_acl(struct inode *inode, int type)
{
struct posix_acl *acl;
char *ea_name;
int size;
char *value = NULL;
switch(type) {
case ACL_TYPE_ACCESS:
ea_name = XATTR_NAME_POSIX_ACL_ACCESS;
break;
case ACL_TYPE_DEFAULT:
ea_name = XATTR_NAME_POSIX_ACL_DEFAULT;
break;
default:
return ERR_PTR(-EINVAL);
}
size = __jfs_getxattr(inode, ea_name, NULL, 0);
if (size > 0) {
value = kmalloc(size, GFP_KERNEL);
if (!value)
return ERR_PTR(-ENOMEM);
size = __jfs_getxattr(inode, ea_name, value, size);
}
if (size < 0) {
if (size == -ENODATA)
acl = NULL;
else
acl = ERR_PTR(size);
} else {
acl = posix_acl_from_xattr(&init_user_ns, value, size);
}
kfree(value);
return acl;
}
static int __jfs_set_acl(tid_t tid, struct inode *inode, int type,
struct posix_acl *acl)
{
char *ea_name;
int rc;
int size = 0;
char *value = NULL;
switch (type) {
case ACL_TYPE_ACCESS:
ea_name = XATTR_NAME_POSIX_ACL_ACCESS;
break;
case ACL_TYPE_DEFAULT:
ea_name = XATTR_NAME_POSIX_ACL_DEFAULT;
break;
default:
return -EINVAL;
}
if (acl) {
size = posix_acl_xattr_size(acl->a_count);
value = kmalloc(size, GFP_KERNEL);
if (!value)
return -ENOMEM;
rc = posix_acl_to_xattr(&init_user_ns, acl, value, size);
if (rc < 0)
goto out;
}
rc = __jfs_setxattr(tid, inode, ea_name, value, size, 0);
out:
kfree(value);
if (!rc)
set_cached_acl(inode, type, acl);
return rc;
}
int jfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
{
int rc;
tid_t tid;
int update_mode = 0;
umode_t mode = inode->i_mode;
tid = txBegin(inode->i_sb, 0);
mutex_lock(&JFS_IP(inode)->commit_mutex);
if (type == ACL_TYPE_ACCESS && acl) {
rc = posix_acl_update_mode(inode, &mode, &acl);
if (rc)
goto end_tx;
update_mode = 1;
}
rc = __jfs_set_acl(tid, inode, type, acl);
if (!rc) {
if (update_mode) {
inode->i_mode = mode;
inode->i_ctime = current_time(inode);
mark_inode_dirty(inode);
}
rc = txCommit(tid, 1, &inode, 0);
}
end_tx:
txEnd(tid);
mutex_unlock(&JFS_IP(inode)->commit_mutex);
return rc;
}
int jfs_init_acl(tid_t tid, struct inode *inode, struct inode *dir)
{
struct posix_acl *default_acl, *acl;
int rc = 0;
rc = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
if (rc)
return rc;
if (default_acl) {
rc = __jfs_set_acl(tid, inode, ACL_TYPE_DEFAULT, default_acl);
posix_acl_release(default_acl);
}
if (acl) {
if (!rc)
rc = __jfs_set_acl(tid, inode, ACL_TYPE_ACCESS, acl);
posix_acl_release(acl);
}
JFS_IP(inode)->mode2 = (JFS_IP(inode)->mode2 & 0xffff0000) |
inode->i_mode;
return rc;
}