linux/fs/cifs/ioctl.c
Al Viro 378ff1a53b fix deadlock in cifs_ioctl_clone()
It really needs to check that src is non-directory *and* use
{un,}lock_two_nodirectories().  As it is, it's trivial to cause
double-lock (ioctl(fd, CIFS_IOC_COPYCHUNK_FILE, fd)) and if the
last argument is an fd of directory, we are asking for trouble
by violating the locking order - all directories go before all
non-directories.  If the last argument is an fd of parent
directory, it has 50% odds of locking child before parent,
which will cause AB-BA deadlock if we race with unlink().

Cc: stable@vger.kernel.org @ 3.13+
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-01-18 23:49:26 -05:00

218 lines
6.1 KiB
C

/*
* fs/cifs/ioctl.c
*
* vfs operations that deal with io control
*
* Copyright (C) International Business Machines Corp., 2005,2013
* Author(s): Steve French (sfrench@us.ibm.com)
*
* This library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published
* by the Free Software Foundation; either version 2.1 of the License, or
* (at your option) any later version.
*
* This library 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/mount.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include "cifspdu.h"
#include "cifsglob.h"
#include "cifsproto.h"
#include "cifs_debug.h"
#include "cifsfs.h"
#define CIFS_IOCTL_MAGIC 0xCF
#define CIFS_IOC_COPYCHUNK_FILE _IOW(CIFS_IOCTL_MAGIC, 3, int)
static long cifs_ioctl_clone(unsigned int xid, struct file *dst_file,
unsigned long srcfd, u64 off, u64 len, u64 destoff)
{
int rc;
struct cifsFileInfo *smb_file_target = dst_file->private_data;
struct inode *target_inode = file_inode(dst_file);
struct cifs_tcon *target_tcon;
struct fd src_file;
struct cifsFileInfo *smb_file_src;
struct inode *src_inode;
struct cifs_tcon *src_tcon;
cifs_dbg(FYI, "ioctl clone range\n");
/* the destination must be opened for writing */
if (!(dst_file->f_mode & FMODE_WRITE)) {
cifs_dbg(FYI, "file target not open for write\n");
return -EINVAL;
}
/* check if target volume is readonly and take reference */
rc = mnt_want_write_file(dst_file);
if (rc) {
cifs_dbg(FYI, "mnt_want_write failed with rc %d\n", rc);
return rc;
}
src_file = fdget(srcfd);
if (!src_file.file) {
rc = -EBADF;
goto out_drop_write;
}
if ((!src_file.file->private_data) || (!dst_file->private_data)) {
rc = -EBADF;
cifs_dbg(VFS, "missing cifsFileInfo on copy range src file\n");
goto out_fput;
}
rc = -EXDEV;
smb_file_target = dst_file->private_data;
smb_file_src = src_file.file->private_data;
src_tcon = tlink_tcon(smb_file_src->tlink);
target_tcon = tlink_tcon(smb_file_target->tlink);
/* check if source and target are on same tree connection */
if (src_tcon != target_tcon) {
cifs_dbg(VFS, "file copy src and target on different volume\n");
goto out_fput;
}
src_inode = file_inode(src_file.file);
rc = -EINVAL;
if (S_ISDIR(src_inode->i_mode))
goto out_fput;
/*
* Note: cifs case is easier than btrfs since server responsible for
* checks for proper open modes and file type and if it wants
* server could even support copy of range where source = target
*/
lock_two_nondirectories(target_inode, src_inode);
/* determine range to clone */
rc = -EINVAL;
if (off + len > src_inode->i_size || off + len < off)
goto out_unlock;
if (len == 0)
len = src_inode->i_size - off;
cifs_dbg(FYI, "about to flush pages\n");
/* should we flush first and last page first */
truncate_inode_pages_range(&target_inode->i_data, destoff,
PAGE_CACHE_ALIGN(destoff + len)-1);
if (target_tcon->ses->server->ops->clone_range)
rc = target_tcon->ses->server->ops->clone_range(xid,
smb_file_src, smb_file_target, off, len, destoff);
/* force revalidate of size and timestamps of target file now
that target is updated on the server */
CIFS_I(target_inode)->time = 0;
out_unlock:
/* although unlocking in the reverse order from locking is not
strictly necessary here it is a little cleaner to be consistent */
unlock_two_nondirectories(src_inode, target_inode);
out_fput:
fdput(src_file);
out_drop_write:
mnt_drop_write_file(dst_file);
return rc;
}
long cifs_ioctl(struct file *filep, unsigned int command, unsigned long arg)
{
struct inode *inode = file_inode(filep);
int rc = -ENOTTY; /* strange error - but the precedent */
unsigned int xid;
struct cifs_sb_info *cifs_sb;
struct cifsFileInfo *pSMBFile = filep->private_data;
struct cifs_tcon *tcon;
__u64 ExtAttrBits = 0;
__u64 caps;
xid = get_xid();
cifs_dbg(FYI, "ioctl file %p cmd %u arg %lu\n", filep, command, arg);
cifs_sb = CIFS_SB(inode->i_sb);
switch (command) {
case FS_IOC_GETFLAGS:
if (pSMBFile == NULL)
break;
tcon = tlink_tcon(pSMBFile->tlink);
caps = le64_to_cpu(tcon->fsUnixInfo.Capability);
#ifdef CONFIG_CIFS_POSIX
if (CIFS_UNIX_EXTATTR_CAP & caps) {
__u64 ExtAttrMask = 0;
rc = CIFSGetExtAttr(xid, tcon,
pSMBFile->fid.netfid,
&ExtAttrBits, &ExtAttrMask);
if (rc == 0)
rc = put_user(ExtAttrBits &
FS_FL_USER_VISIBLE,
(int __user *)arg);
if (rc != EOPNOTSUPP)
break;
}
#endif /* CONFIG_CIFS_POSIX */
rc = 0;
if (CIFS_I(inode)->cifsAttrs & ATTR_COMPRESSED) {
/* add in the compressed bit */
ExtAttrBits = FS_COMPR_FL;
rc = put_user(ExtAttrBits & FS_FL_USER_VISIBLE,
(int __user *)arg);
}
break;
case FS_IOC_SETFLAGS:
if (pSMBFile == NULL)
break;
tcon = tlink_tcon(pSMBFile->tlink);
caps = le64_to_cpu(tcon->fsUnixInfo.Capability);
if (get_user(ExtAttrBits, (int __user *)arg)) {
rc = -EFAULT;
break;
}
/*
* if (CIFS_UNIX_EXTATTR_CAP & caps)
* rc = CIFSSetExtAttr(xid, tcon,
* pSMBFile->fid.netfid,
* extAttrBits,
* &ExtAttrMask);
* if (rc != EOPNOTSUPP)
* break;
*/
/* Currently only flag we can set is compressed flag */
if ((ExtAttrBits & FS_COMPR_FL) == 0)
break;
/* Try to set compress flag */
if (tcon->ses->server->ops->set_compression) {
rc = tcon->ses->server->ops->set_compression(
xid, tcon, pSMBFile);
cifs_dbg(FYI, "set compress flag rc %d\n", rc);
}
break;
case CIFS_IOC_COPYCHUNK_FILE:
rc = cifs_ioctl_clone(xid, filep, arg, 0, 0, 0);
break;
default:
cifs_dbg(FYI, "unsupported ioctl\n");
break;
}
free_xid(xid);
return rc;
}