man/man8/lofiadm.8

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.Dd Jun 14, 2016
.Dt LOFIADM 8
.Os
.Sh NAME
.Nm lofiadm
.Nd administer files available as block devices through lofi
.Sh SYNOPSIS
.Nm
.Op Fl r
.Op Fl l
.Fl a Ar file Op Ar device
.Nm
.Op Fl r
.Fl c
.Ar crypto_algorithm
.Fl a
.Ar file Op Ar device
.Nm
.Op Fl r
.Fl c Ar crypto_algorithm
.Fl k Ar raw_key_file
.Fl a  Ar file Op Ar device
.Nm
.Op Fl r
.Fl c Ar crypto_algorithm
.Fl T Ar token_key
.Fl a Ar file Op Ar device
.Nm
.Op Fl r
.Fl c Ar crypto_algorithm
.Fl T Ar token_key
.Fl k Ar wrapped_key_file
.Fl a Ar file Op Ar device
.Nm
.Op Fl r
.Fl c Ar crypto_algorithm
.Fl e
.Fl a Ar file Op Ar device
.Nm
.Fl C Ar algorithm
.Op Fl s Ar segment_size
.Ar file
.Nm
.Fl d Ar file Ns | Ns Ar device
.Nm
.Fl U Ar file
.Nm
.Op Ar file Ns | Ns device
.Sh DESCRIPTION
.Nm
administers
.Sy lofi ,
the loopback file driver.
.Sy lofi
allows a file to be associated with a block device.
That file can then be accessed through the block device.
This is useful when the file contains an image of some filesystem (such as a
floppy or
.Sy CD-ROM
image), because the block device can then be used with the normal system
utilities for mounting, checking or repairing filesystems.
See
.Xr fsck 8
and
.Xr mount 8 .
.Pp
Use
.Nm
to add a file as a loopback device, remove such an
association, or print information about the current associations.
.Pp
Encryption and compression options are mutually exclusive on the command line.
Further, an encrypted file cannot be compressed later, nor can a compressed
file be encrypted later.
.Pp
In the global zone,
.Nm
can be used on both the global
zone devices and all devices owned by other non-global zones on the system.
.Ss Labeled Devices
If the command line flag,
.Fl l ,
is used while creating a loopack device,
.Sy lofi
will create a labeled loopback
device, and will generate device links in
.Pa /dev/{dsk,rdsk}
directories for partitions or slices.
.Pp
Before using these devices, users should create or verify
partitioning by using partition management tools such as
.Xr format 8 and
.Xr fdisk 8 .
Once the device has been appropriately partitioned, the labeled
device can be used as normal disk to create and mount file systems and to store
data.
Mappings created by
.Nm
are not permanent and not persisted by the system.
If power is lost or the system is rebooted, then the mappings will need to be
created again.
.Pp
The partition table requires space from the mapped file.
.Sy lofi
does not support converting previously created unlabeled loopback device images
to labeled loopback devices.
If an unlabeled device is used as a labeled device, writing to it will corrupt
it.
.Sh OPTIONS
The following options are supported:
.Bl -tag -width Ds
.It Fl a Ar file Op Ar device
Add
.Sy file
as a block device.
.Pp
If
.Sy device
is not specified, an available device is picked.
.Pp
If
.Sy device
is specified,
.Nm
attempts to assign it to
.Sy file .
.Sy device
must be available or
.Nm
will fail.
The ability to specify a device is provided for use in scripts that wish to
reestablish a particular set of associations.
A device may not be specified when using a labeled lofi device.
.It Fl C Ar {gzip | gzip-N | lzma}
Compress the file with the specified compression algorithm.
.Pp
The
.Sy gzip
compression algorithm uses the same compression as the open-source
.Sy gzip
command.
You can specify the
.Sy gzip
level by using the value gzip-\fR\fIN\fR where \fIN\fR is 6 (fast) or 9
(best compression ratio).
Currently,
.Sy gzip ,
without a number, is equivalent to
.Sy gzip-6
(which is also the default for the
.Sy gzip
command).
.Pp
.Sy lzma
stands for the LZMA (Lempel-Ziv-Markov) compression algorithm.
.Pp
Note that you cannot write to a compressed file, nor can you mount a compressed
file read/write.
.It Fl d Ar file Ns | Ns Ar device
Remove an association by
.Sy file
or
.Sy device
name, if the associated block device is not busy, and deallocates the block
device.
.It Fl l
This option should be used with
.Fl a
option to create labeled loopback device.
If created in local zone, the device has to be enabled in zone configuration.
.It Fl r
If the
.Fl r
option is specified before the
.Fl a
option, the
.Sy device
will be opened read-only.
.It Fl s Ar segment_size
The segment size to use to divide the file being compressed.
.Sy segment_size
can be an integer multiple of 512.
.It Fl U Ar file
Uncompress a compressed file.
.El
.Pp
The following options are used when the file is encrypted:
.Bl -tag -width Ds
.It Fl c Ar crypto_algorithm
Select the encryption algorithm.
The algorithm must be specified when encryption is enabled because the algorithm
is not stored in the disk image.
.Pp
If none of
.Fl e ,
.Fl k ,
or
.Fl T
is specified,
.Nm
prompts for a passphrase, with a minimum length of eight characters, to be
entered.
The passphrase is used to derive a symmetric encryption key using PKCS#5 PBKD2.
.It Fl k Ar raw_key_file | Ar wrapped_key_file
Path to raw or wrapped symmetric encryption key.
If a PKCS#11 object is also given with the
.Fl T
option, then the key is wrapped by that object.
If
.Fl T
is not specified, the key is used raw.
.It Fl T Ar token_key
The key in a PKCS#11 token to use for the encryption or for unwrapping the key
file.
.Pp
If
.Fl k
is also specified,
.Fl T
identifies the unwrapping key, which must be an RSA private key.
.It Fl e
Generate an ephemeral symmetric encryption key.
.El
.Sh OPERANDS
The following operands are supported:
.Bl -tag -width Ds
.It Ar crypto_algorithm
One of:
.Sy aes-128-cbc ,
.Sy aes-192-cbc ,
.Sy aes-256-cbc ,
.Sy des3-cbc ,
.Sy blowfish-cbc .
.It Ar device
Display the file name associated with the block device
.Sy device .
.Pp
Without arguments, print a list of the current associations.
Filenames must be valid absolute pathnames.
.Pp
When a file is added, it is opened for reading or writing by root.
Any restrictions apply (such as restricted root access over
.Sy NFS Ns ).
The file is held open until the association is removed.
It is not actually accessed until the block device is used, so it will never be
written to if the block device is only opened read-only.
.Pp
Note that the filename may appear as "?" if it is not possible to resolve the
path in the current context (for example, if it's an NFS path in a non-global
zone).
.It Ar file
Display the block device associated with
.Sy file .
.It Ar raw_key_file
Path to a file of the appropriate length, in bits, to use as a raw symmetric
encryption key.
.It Ar token_key
PKCS#11 token object in the format:
.Pp
.Ar token_name Ns \&: Ns Ar manufacturer_id Ns \&: Ns
.Ar serial_number Ns \&: Ns Ar key_label
.Pp
All but the key label are optional and can be empty.
For example, to specify a token object with only its key label
.Sy MylofiKey ,
use
.Fl T Sy :::MylofiKey .
.It Ar wrapped_key_file
Path to file containing a symmetric encryption key wrapped by the RSA private
key specified by
.Fl T .
.El
.Sh ENVIRONMENT
See
.Xr environ 7
for descriptions of the following environment variables
that affect the execution of
.Nm
:
.Sy LC_CTYPE ,
.Sy LC_MESSAGES
and
.Sy NLSPATH .
.Sh EXIT STATUS
The following exit values are returned:
.Bl -tag -width Ds
.It Sy 0
Successful completion.
.It Sy >0
An error occurred.
.El
.Sh EXAMPLES
.Bl -tag -width Ds
.It Sy Example 1 No Mounting an Existing CD-ROM Image
You should ensure that Solaris understands the image before creating the
.Sy CD .
.Sy lofi
allows you to mount the image and see if it works.
.Pp
This example mounts an existing
.Sy CD-ROM
image
.Pf ( Sy sparc.iso Ns ),
of the
.Sy Red Hat 6.0 CD
which was downloaded from the Internet.
It was created with the
.Sy mkisofs
utility from the Internet.
.Pp
Use
.Nm
to attach a block device to it:
.Bd -literal
# lofiadm -a /home/mike_s/RH6.0/sparc.iso
/dev/lofi/1
.Ed
.Pp
.Nm
picks the device and prints the device name to the standard
output.
You can run
.Nm
again by issuing the following command:
.Bd -literal
# lofiadm
Block Device     File                           Options
/dev/lofi/1      /home/mike_s/RH6.0/sparc.iso   -
.Ed
.Pp
Or, you can give it one name and ask for the other, by issuing the following
command:
.Bd -literal
# lofiadm /dev/lofi/1
/home/mike_s/RH6.0/sparc.iso
.Ed
.Pp
Use the
.Xr mount 8
command to mount the image:
.Bd -literal
# mount -F hsfs -o ro /dev/lofi/1 /mnt
.Ed
.Pp
Check to ensure that Solaris understands the image:
.Bd -literal
# df -k /mnt
Filesystem            kbytes    used   avail capacity  Mounted on
/dev/lofi/1           512418  512418       0   100%    /mnt
# ls /mnt
\&./            RedHat/       doc/          ls-lR         rr_moved/
\&../           TRANS.TBL     dosutils/     ls-lR.gz      sbin@
\&.buildlog     bin@          etc@          misc/         tmp/
COPYING       boot/         images/       mnt/          usr@
README        boot.cat*     kernels/      modules/
RPM-PGP-KEY   dev@          lib@          proc/
.Ed
.Pp
Solaris can mount the CD-ROM image, and understand the filenames.
The image was created properly, and you can now create the
.Sy CD-ROM
with confidence.
.Pp
As a final step, unmount and detach the images:
.Bd -literal
# umount /mnt
# lofiadm -d /dev/lofi/1
# lofiadm
Block Device             File             Options
.Ed
.It Sy Example 2 No Mounting a Floppy Image
This is similar to the first example.
.Pp
Using
.Sy lofi
to help you mount files that contain floppy images is helpful
if a floppy disk contains a file that you need, but the machine which you are
on does not have a floppy drive.
It is also helpful if you do not want to take the time to use the
.Sy dd
command to copy the image to a floppy.
.Pp
This is an example of getting to
.Sy MDB
floppy for Solaris on an x86 platform:
.Bd -literal
# lofiadm -a /export/s28/MDB_s28x_wos/latest/boot.3
/dev/lofi/1
# mount -F pcfs /dev/lofi/1 /mnt
# ls /mnt
\&./            COMMENT.BAT*  RC.D/         SOLARIS.MAP*
\&../           IDENT*        REPLACE.BAT*  X/
APPEND.BAT*   MAKEDIR.BAT*  SOLARIS/
# umount /mnt
# lofiadm -d /export/s28/MDB_s28x_wos/latest/boot.3
.Ed
.It Sy Example 3 No Making a Sy UFS No Filesystem on a File
Making a
.Sy UFS
filesystem on a file can be useful, particularly if a test
suite requires a scratch filesystem.
It can be painful (or annoying) to have to repartition a disk just for the test
suite, but you do not have to.
You can
.Sy newfs
a file with
.Sy lofi .
.Pp
Create the file:
.Bd -literal
# mkfile 35m /export/home/test
.Ed
.Pp
Attach it to a block device.
You also get the character device that
.Sy newfs
requires, so
.Sy newfs
that:
.Bd -literal
# lofiadm -a /export/home/test
/dev/lofi/1
# newfs /dev/rlofi/1
newfs: construct a new file system /dev/rlofi/1: (y/n)? y
/dev/rlofi/1:   71638 sectors in 119 cylinders of 1 tracks, 602 sectors
        35.0MB in 8 cyl groups (16 c/g, 4.70MB/g, 2240 i/g)
super-block backups (for fsck -F ufs -o b=#) at:
 32, 9664, 19296, 28928, 38560, 48192, 57824, 67456,
.Ed
.Pp
Note that
.Sy ufs
might not be able to use the entire file.
Mount and use the filesystem:
.Bd -literal
# mount /dev/lofi/1 /mnt
# df -k /mnt
Filesystem            kbytes    used   avail capacity  Mounted on
/dev/lofi/1            33455       9   30101     1%    /mnt
# ls /mnt
\&./           ../          lost+found/
# umount /mnt
# lofiadm -d /dev/lofi/1
.Ed
.It Sy Example 4 No Creating a PC (FAT) File System on a Unix File
The following series of commands creates a
.Sy FAT
file system on a Unix file.
The file is associated with a block device created by
.Nm
.
.Bd -literal
# mkfile 10M /export/test/testfs
# lofiadm -a /export/test testfs
/dev/lofi/1
.Ed
.Pp
Note use of
.Sy rlofi ,
not
.Sy lofi ,
in following command.
.Bd -literal
# mkfs -F pcfs -o nofdisk,size=20480 /dev/rlofi/1
Construct a new FAT file system on /dev/rlofi/1: (y/n)? y
# mount -F pcfs /dev/lofi/1 /mnt
# cd /mnt
# df -k .
Filesystem            kbytes    used   avail capacity  Mounted on
/dev/lofi/1            10142       0   10142     0%    /mnt
.Ed
.It Sy Example 5 No Compressing an Existing CD-ROM Image
The following example illustrates compressing an existing CD-ROM image
.Pf ( Sy solaris.iso Ns ),
verifying that the image is compressed, and then uncompressing it.
.Bd -literal
# lofiadm -C gzip /export/home/solaris.iso
.Ed
.Pp
Use
.Nm
to attach a block device to it:
.Bd -literal
# lofiadm -a /export/home/solaris.iso
  /dev/lofi/1
.Ed
.Pp
Check if the mapped image is compressed:
.Bd -literal
# lofiadm
Block Device      File                            Options
/dev/lofi/1       /export/home/solaris.iso        Compressed(gzip)
/dev/lofi/2       /export/home/regular.iso        -
.Ed
.Pp
Unmap the compressed image and uncompress it:
.Bd -literal
# lofiadm -d /dev/lofi/1
# lofiadm -U /export/home/solaris.iso
.Ed
.It Sy Example 6 No Creating an Encrypted UFS File System on a File
This example is similar to the example of making a UFS filesystem on a file,
above.
.Pp
Create the file:
.Bd -literal
# mkfile 35m /export/home/test
.Ed
.Pp
Attach the file to a block device and specify that the file image is encrypted.
As a result of this command, you obtain the character device, which is
subsequently used by
.Sy newfs :
.Bd -literal
# lofiadm -c aes-256-cbc -a /export/home/secrets
Enter passphrase: My-M0th3r;l0v3s_m3+4lw4ys!           (not echoed)
Re-enter passphrase: My-M0th3r;l0v3s_m3+4lw4ys!        (not echoed)
/dev/lofi/1

# newfs /dev/rlofi/1
newfs: construct a new file system /dev/rlofi/1: (y/n)? y
/dev/rlofi/1:   71638 sectors in 119 cylinders of 1 tracks, 602 sectors
       35.0MB in 8 cyl groups (16 c/g, 4.70MB/g, 2240 i/g)
super-block backups (for fsck -F ufs -o b=#) at:
32, 9664, 19296, 28928, 38560, 48192, 57824, 67456,
.Ed
.Pp
The mapped file system shows that encryption is enabled:
.Bd -literal
# lofiadm
Block Device    File                     Options
/dev/lofi/1     /export/home/secrets     Encrypted
.Ed
.Pp
Mount and use the filesystem:
.Bd -literal
# mount /dev/lofi/1 /mnt
# cp moms_secret_*_recipe /mnt
# ls /mnt
\&./         moms_secret_cookie_recipe    moms_secret_soup_recipe
\&../        moms_secret_fudge_recipe     moms_secret_stuffing_recipe
lost+found/  moms_secret_meatloaf_recipe  moms_secret_waffle_recipe
# umount /mnt
# lofiadm -d /dev/lofi/1
.Ed
.Pp
Subsequent attempts to map the filesystem with the wrong key or the wrong
encryption algorithm will fail:
.Bd -literal
# lofiadm -c blowfish-cbc -a /export/home/secrets\fR
Enter passphrase: mommy                                (not echoed)
Re-enter passphrase: mommy                             (not echoed)
lofiadm: could not map file /root/lofi: Invalid argument
# lofiadm
Block Device    File                    Options
#
.Ed
.Pp
Attempts to map the filesystem without encryption will succeed, however
attempts to mount and use the filesystem will fail:
.Bd -literal
# lofiadm -a /export/home/secrets
/dev/lofi/1
# lofiadm
Block Device    File                     Options
/dev/lofi/1     /export/home/secrets     -
# mount /dev/lofi/1 /mnt
mount: /dev/lofi/1 is not this fstype
#
.Ed
.El
.Sh SEE ALSO
.Xr lofi 4D ,
.Xr lofs 4FS ,
.Xr attributes 7 ,
.Xr fdisk 8 ,
.Xr format 8 ,
.Xr fsck 8 ,
.Xr mount 8 ,
.Xr mount_ufs 8 ,
.Xr newfs 8
.Sh NOTES
Just as you would not directly access a disk device that has mounted file
systems, you should not access a file associated with a block device except
through the
.Sy lofi
file driver.
It might also be appropriate to ensure that the file has appropriate permissions
to prevent such access.
.Pp
The abilities of
.Nm
, and who can use them, are controlled by the
permissions of
.Pa /dev/lofictl .
Read-access allows query operations, such as
listing all the associations.
Write-access is required to do any state-changing operations, like adding an
association.
As shipped,
.Pa /dev/lofictl
is owned by
.Sy root ,
in group
.Sy sys ,
and mode
.Sy 0644 ,
so all users can do query operations but only root can change anything.
The administrator can give users write-access, allowing them to add or
delete associations, but that is very likely a security hole and should
probably only be given to a trusted group.
.Pp
When mounting a filesystem image, take care to use appropriate mount options.
In particular, the
.Sy nosuid
mount option might be appropriate for
.Sy UFS
images whose origin is unknown.
Also, some options might not be useful or appropriate, like
.Sy logging
or
.Sy forcedirectio
for
.Sy UFS .
For compatibility purposes, a raw device is also exported along with the block
device.
For example,
.Xr newfs 8
requires one.
.Pp
The output of
.Nm
(without arguments) might change in future releases.