Arch Linux

Wild Penguin

Member

Registered: 2015-03-19

Posts: 407

I can not mount with loop option as a user (CD etc. images)

Hi!

I often need to work with CD/floppy/HDD images for retro gaming.

I have made a bit hacky, I must admit, setup in my fstab as such:

# Image script mount points
/mnt/image/.image.CD                                                    /mnt/image/cd   auto            noatime,user,noauto,loop        0 0
/mnt/image/.image.1                             /mnt/image/1    auto            noatime,user,noauto,loop        0 0
/mnt/image/.image.2                             /mnt/image/2    auto            noatime,user,noauto,loop        0 0
/mnt/image/.image.3                             /mnt/image/3    auto            noatime,user,noauto,loop        0 0
/mnt/image/.image.4                             /mnt/image/4    auto            noatime,user,noauto,loop        0 0
/mnt/image/.image.5                             /mnt/image/5    auto            noatime,user,noauto,loop        0 0
/mnt/image/.image.6                             /mnt/image/6    auto            noatime,user,noauto,loop        0 0
/mnt/image/.image.7                             /mnt/image/7    auto            noatime,user,noauto,loop        0 0
/mnt/image/.image.8                             /mnt/image/8    auto            noatime,user,noauto,loop        0 0
/mnt/image/.image.9                             /mnt/image/9    auto            noatime,user,noauto,loop        0 0

The user can write / change symbolic links at the .image.* files. Yes, this is not probably a secure and not advisable as a general thing to do, but it's my personal computer, and if someone besides me gains access to writing to those symbolic links, I got bigger problems to worry about. Sometimes I mess around a lot with image files. This has worked fine for me.

At some point, this set up has stopped working. I don't know precisely when since there can be months of gaps when I do not use these mount points. I suppose there has been some security-related setting or default behavior which was changed at some point in kernel or systemd, but this is all a guess and speculation.

With this fstab I used to be able to mount images just by:

ln -sf "$imgfile" ${IMAGELINKPREFIX}.image.$IMAGESUFFIX

mount "$MOUNTPOINT"

But currently, as I try to mount I just get (when running the mount command, link creation is fine):

mount: /mnt/image/cd: failed to set up loop device for /mnt/image/.image.CD.

I still need to mount as root despite having "user" in fstab (i.e.; perhaps a more concise description of the problem would be: can not mount with loop,user options in fstab).

I can see this could be an A instead of B problem; is you have suggestions on how to set up / use images instead of constantly needing to use sudo, suggestions are welcome. Maybe creating a script solely for this, and set it up as NOPASSWD in sudoers....

Last edited by Wild Penguin (Today 16:40:55)

jonno2002

Member

Registered: 2016-11-21

Posts: 921

Re: I can not mount with loop option as a user (CD etc. images)

after reading this i found this:
https://wiki.archlinux.org/title/FuseISO
how have i not known about this, i always use root to mount images, i guess you learn/find somthing new everyday.

seth

Member

From: Won't reply 2 private help req

Registered: 2012-09-03

Posts: 78,655

Re: I can not mount with loop option as a user (CD etc. images)

https://wiki.archlinux.org/title/Udisks … op_devices ?

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