[SOLVED] DVD mounted without read permissions. How to add read permission to UDF?

How to get read permissions on a DVD-RW with UDF that was recorded from a DVD recorder?

I would like to watch old videos from a DVD-RW written with a DVD recorder, but it can't be accessed from Linux because it has no read permission:

$ stat StorageLabs\ TinyUDF\ Volume/
  File: StorageLabs TinyUDF Volume/
  Size: 136       	Blocks: 4          IO Block: 2048   directory
Device: 700h/1792d	Inode: 1299        Links: 4
Access: (0000/d---------)  Uid: (29999/username)   Gid: (29999/username)
Access: 1970-01-01 01:00:00.000000000 +0100
Modify: 1970-01-01 01:00:00.000000000 +0100
Change: 1970-01-01 01:00:00.000000000 +0100
 Birth: -

Making an image from the disc doesn't help, since it is always mounted read-only.

$ sudo mount DVD.iso ../UDF -o rw
mount: /media/username/UDF: WARNING: source write-protected, mounted read-only.
$ sudo chmod a+r /media/username/UDF
chmod: changing permissions of '/media/username/UDF': Read-only file system

Accessing the disc on Windows is trivial (it appears in the file explorer immediately) since it doesn't know Unix permissions.

How do I get read permissions on that UDF disc?

Do I have to resort to using 7z? (It happens to be able to read UDF images. While one could access some files using pipes (stdin / stdout), they are not seekable.)

sudo mount DVD.iso ../UDF -o rw mount: /media/username/UDF: WARNING: source write-protected, mounted read-only.

Says that it is mounted.

A DVD will be read only. ISO9660 or UDF. You can't write to a finalized DVD.

sudo mount dvd.iso ~/mount/point

Look in ~/mount/point for the contents.

Edit:
Or, excuse me, you can't write to an .iso either. It is read only.

Originally Posted by teckk Says that it is mounted. A DVD will be read only. ISO9660 or UDF. You can't write to a finalized DVD.

I know. The problem is that it is mounted without any read permissions, and the permission can not be changed.

Not even this works:

$ sudo mount DVD.iso /media/username/UDF -o uid=29999,gid=29999
mount: /media/username/UDF: WARNING: source write-protected, mounted read-only.
$ stat /media/username/UDF
  File: UDF
  Size: 136       	Blocks: 4          IO Block: 2048   directory
Device: 700h/1792d	Inode: 1299        Links: 4
Access: (0000/d---------)  Uid: (29999/username)   Gid: (29999/username)
Access: 1970-01-01 01:00:00.000000000 +0100
Modify: 1970-01-01 01:00:00.000000000 +0100
Change: 1970-01-01 01:00:00.000000000 +0100
 Birth: -

This normally works for exFAT (if not automatically mounted by udisks).

The umask and uid options unfortunately didn't help. I still get 000 permissions.

$ mkdir UDF
$ sudo mount DVD.iso UDF -o umask=777,uid=29999,dmode=777
[sudo] password for oem:           
mount: UDF: WARNING: source write-protected, mounted read-only.
$ stat UDF
  File: UDF
  Size: 136       	Blocks: 4          IO Block: 2048   directory
Device: 703h/1795d	Inode: 1299        Links: 4
Access: (0000/d---------)  Uid: (29999/     oem)   Gid: (    0/    root)
Access: 1970-01-01 01:00:00.000000000 +0100
Modify: 1970-01-01 01:00:00.000000000 +0100
Change: 1970-01-01 01:00:00.000000000 +0100
 Birth: -
$ ls UDF
ls: cannot open directory 'UDF': Permission denied
$ sudo umount UDF

The manual suggests it should work, but it doesn't:

   Mount options for udf
       UDF is the "Universal Disk Format" filesystem defined by OSTA, the Optical Storage Technology Association, and is often used for DVD-ROM, frequently in the form of a hybrid UDF/ISO-9660
       filesystem. It is, however, perfectly usable by itself on disk drives, flash drives and other block devices. See also iso9660.

       uid=
           Make all files in the filesystem belong to the given user. uid=forget can be specified independently of (or usually in addition to) uid=<user> and results in UDF not storing uids to
           the media. In fact the recorded uid is the 32-bit overflow uid -1 as defined by the UDF standard. The value is given as either <user> which is a valid user name or the corresponding
           decimal user id, or the special string "forget".

       gid=
           Make all files in the filesystem belong to the given group. gid=forget can be specified independently of (or usually in addition to) gid=<group> and results in UDF not storing gids
           to the media. In fact the recorded gid is the 32-bit overflow gid -1 as defined by the UDF standard. The value is given as either <group> which is a valid group name or the
           corresponding decimal group id, or the special string "forget".

       umask=
           Mask out the given permissions from all inodes read from the filesystem. The value is given in octal.

       mode=
           If mode= is set the permissions of all non-directory inodes read from the filesystem will be set to the given mode. The value is given in octal.

       dmode=
           If dmode= is set the permissions of all directory inodes read from the filesystem will be set to the given dmode. The value is given in octal.

Did you try explicitly tell to mount udf? Also using loop to mount the image

mount -t udf -o loop DVD.iso UDF

Maybe see output of dmesg after that

mount DVD.iso /mnt/DVD -t udf -o ro,mode=555,dmode=555

I confused "mode" with "mask". "mask" subtracts permission bits! "dmode" is an exclusive option for UDF.

yes, it was documented: umask= Mask out the given permissions... umask 777 will make it 000

Originally Posted by pan64 yes, it was documented: umask= Mask out the given permissions... umask 777 will make it 000

On the DVD image in question, all files and folders had 000 permissions by default (no mounting parameters) because the DVD recorder that created the disc didn't set any Unix permission bits. So umask 777 lead to the same results because there were no bits to mask out.