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linux/fs/cifs/ioctl.c
Jann Horn 4c17a6d56b CIFS: fix type confusion in copy offload ioctl 
This might lead to local privilege escalation (code execution as
kernel) for systems where the following conditions are met:

 - CONFIG_CIFS_SMB2 and CONFIG_CIFS_POSIX are enabled
 - a cifs filesystem is mounted where:
  - the mount option "vers" was used and set to a value >=2.0
  - the attacker has write access to at least one file on the filesystem

To attack this, an attacker would have to guess the target_tcon
pointer (but guessing wrong doesn't cause a crash, it just returns an
error code) and win a narrow race.

CC: Stable <stable@vger.kernel.org>
Signed-off-by: Jann Horn <jann@thejh.net>
Signed-off-by: Steve French <smfrench@gmail.com>
2015-09-11 09:54:03 -05:00

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8.1 KiB
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/*
* 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"
#include "cifs_ioctl.h"
#include <linux/btrfs.h>
static long cifs_ioctl_clone(unsigned int xid, struct file *dst_file,
unsigned long srcfd, u64 off, u64 len, u64 destoff,
bool dup_extents)
{
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->f_op->unlocked_ioctl != cifs_ioctl) {
rc = -EBADF;
cifs_dbg(VFS, "src file seems to be from a different filesystem type\n");
goto out_fput;
}
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 (dup_extents && target_tcon->ses->server->ops->duplicate_extents)
rc = target_tcon->ses->server->ops->duplicate_extents(xid,
smb_file_src, smb_file_target, off, len, destoff);
else if (!dup_extents && 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);
else
rc = -EOPNOTSUPP;
/* 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;
}
static long smb_mnt_get_fsinfo(unsigned int xid, struct cifs_tcon *tcon,
void __user *arg)
{
int rc = 0;
struct smb_mnt_fs_info *fsinf;
fsinf = kzalloc(sizeof(struct smb_mnt_fs_info), GFP_KERNEL);
if (fsinf == NULL)
return -ENOMEM;
fsinf->version = 1;
fsinf->protocol_id = tcon->ses->server->vals->protocol_id;
fsinf->device_characteristics =
le32_to_cpu(tcon->fsDevInfo.DeviceCharacteristics);
fsinf->device_type = le32_to_cpu(tcon->fsDevInfo.DeviceType);
fsinf->fs_attributes = le32_to_cpu(tcon->fsAttrInfo.Attributes);
fsinf->max_path_component =
le32_to_cpu(tcon->fsAttrInfo.MaxPathNameComponentLength);
#ifdef CONFIG_CIFS_SMB2
fsinf->vol_serial_number = tcon->vol_serial_number;
fsinf->vol_create_time = le64_to_cpu(tcon->vol_create_time);
fsinf->share_flags = tcon->share_flags;
fsinf->share_caps = le32_to_cpu(tcon->capabilities);
fsinf->sector_flags = tcon->ss_flags;
fsinf->optimal_sector_size = tcon->perf_sector_size;
fsinf->max_bytes_chunk = tcon->max_bytes_chunk;
fsinf->maximal_access = tcon->maximal_access;
#endif /* SMB2 */
fsinf->cifs_posix_caps = le64_to_cpu(tcon->fsUnixInfo.Capability);
if (copy_to_user(arg, fsinf, sizeof(struct smb_mnt_fs_info)))
rc = -EFAULT;
kfree(fsinf);
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_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, false);
break;
case BTRFS_IOC_CLONE:
rc = cifs_ioctl_clone(xid, filep, arg, 0, 0, 0, true);
break;
case CIFS_IOC_SET_INTEGRITY:
if (pSMBFile == NULL)
break;
tcon = tlink_tcon(pSMBFile->tlink);
if (tcon->ses->server->ops->set_integrity)
rc = tcon->ses->server->ops->set_integrity(xid,
tcon, pSMBFile);
else
rc = -EOPNOTSUPP;
break;
case CIFS_IOC_GET_MNT_INFO:
tcon = tlink_tcon(pSMBFile->tlink);
rc = smb_mnt_get_fsinfo(xid, tcon, (void __user *)arg);
break;
default:
cifs_dbg(FYI, "unsupported ioctl\n");
break;
}
free_xid(xid);
return rc;
}
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