Manas Laha wrote:


Linux Lover wrote:

Arko Provo Mukherjee wrote:

Hello,
I think you didn't get the point. When writing the CD it is done in raw
mode and you don't need to mount. So the permissions given during
mounting doesn't matter.
Hope that helps.
Arko

Good help. Satisfied with this explaination. Now, what is ringing to my mind is that, in similar way, may some virus or spyware get access into our read only hard disks (better to say read only partitions in my hard disk) too?

Regards
Anindya



So we are agreed that if a device is not mounted then the permissions stated in /etc/fstab don't matter. Individual files and directories on such a device will not be accessible in the usual way.

However, in that case we may still read/write from/to the raw device provided the permissions on this device are right. For example, on my PC which runs Linux Red Hat 8.0, the cd-writer is /dev/scd0 and here are the permissions:

6108 0 brw-rw-rw- 1 root disk 11, 0 Aug 31 2002 /dev/scd0

As you can see, root is the owner of this device but everyone has read and write permissions to it. On this same system the permissions for the first hard disk (/dev/hda) and its partitions are:

4524 0 brw-rw---- 1 root disk 3, 0 Aug 31 2002 /dev/hda 4525 0 brw-rw---- 1 root disk 3, 1 Aug 31 2002 /dev/hda1 4536 0 brw-rw---- 1 root disk 3, 2 Aug 31 2002 /dev/hda2 4547 0 brw-rw---- 1 root disk 3, 3 Aug 31 2002 /dev/hda3 4551 0 brw-rw---- 1 root disk 3, 4 Aug 31 2002 /dev/hda4 4552 0 brw-rw---- 1 root disk 3, 5 Aug 31 2002 /dev/hda5

so only root and users belonging to group `disk' may read/write from/to this disk. Therefore unless a virus runs with root privileges (or manages to run with the privileges of a user belonging to the `disk' group) it cannot access the raw disk devices.

When the disk partitions are mounted then of course access is possible through the file system and the individual file or directory file permissions apply.

- Manas Laha


!!!GREAT !!!

Thank you Manas for this type of nice presentation. Now the thing is clear to me.

My best regards to you and APM too

Regards
Anindya



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