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if the user has full access to the image file (iso or disk image), will there be any security problem to permit him set up a loopback device backed by this file ?

% ls -al /dev/loop*                                                                                                                                                                  
brw-rw---T 1 root disk  7,   0 Jul 15 16:39 /dev/loop0
brw-rw---T 1 root disk  7,   1 Jun 17 15:58 /dev/loop1
brw-rw---T 1 root disk  7,   2 Jun 17 15:58 /dev/loop2
brw-rw---T 1 root disk  7,   3 Jun 17 15:58 /dev/loop3
brw-rw---T 1 root disk  7,   4 Jun 17 15:58 /dev/loop4
brw-rw---T 1 root disk  7,   5 Jun 17 15:58 /dev/loop5
brw-rw---T 1 root disk  7,   6 Jun 17 15:58 /dev/loop6
brw-rw---T 1 root disk  7,   7 Jun 17 15:58 /dev/loop7
crw------T 1 root root 10, 237 Jun 17 15:58 /dev/loop-control

the loopX is belonged to disk group

% id
uid=1000(user) gid=1000(user) groups=1000(user),6(disk)

I'm in disk group. So, I can use the loopback device

% /sbin/losetup -f ~/disk.img

% /sbin/losetup -a
/dev/loop0: [0809]:2097347 (/home/user/disk.img)

But any user isn't in disk group can't use the loopback device, is there any problem to permit everyone to use the loopback ?

PS: by using mount namespace, any user can mount disks, but the root requirement of loopback device prevent user from mounting disk images.

share|improve this question
@goldilocks definitely not, there is no suid or nodev involved by using loopback device. – Zang MingJie Jul 15 '13 at 9:17
Alright, I misunderstood what you are looking for here. – goldilocks Jul 15 '13 at 9:26
@goldilocks maybe my question title is misleading – Zang MingJie Jul 15 '13 at 9:27
Probably not, lol, I just see duplicates too easily. It is a fair and straightforward question. I don't know the answer, unfortunately. Although some of the similar questions about mounting have some suggestions about alternatives to granting privileges, I suppose privileges would be easiest. – goldilocks Jul 15 '13 at 9:40

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