Home / ubuntu / Questions / 1303919
In Process
opinion_no9
Asked: 2020-12-31 08:39:31 +0800 CST

no execution (rights) at home / can not make /home executable (exec) when using encrypted (LUKS) / mounted home

  • 772

The issue:

I do not have / lost executable rights in my /home. Which is quite devastating for TOR onion use. This pops up on increasing number of machines with Ubuntu 20.xxSome new set up and some worked with existing exec rights before .

Situation:

  • sometimes this occurs irreversible on runing systems.
  • The execute rights for the file and directory and "/home" are given and OK.
  • /home is a mount because it is encrypted / a LUKS partition.
  • The "exec" IS given in fstab (/dev/mapper/luks-12345 /home ext4 exec,rw,users 0 2) but it is IGNORED.
  • Doing a rw re-mount is successful and used for workaround: from /etc/systemd/system/ start service doing "mount -o remount,rw /dev/mapper/luks-12345 /home/" This shows it is not an issue of missing exec rights with files or directories. This workaround is ugly and only cures symptoms.

Mount is reported as:

/home     /dev/mapper/luks-12345 ext4  rw,nosuid,nodev,**noexec**,relatime

although set as exec in fstab.

Question:

  • Why is the mount option "exec" ignored (on an increasing number of machines)?

Example executed in ~:

$ ./myscript.sh
bash: ./myscript.sh: Keine Berechtigung   (translate: no rights)

same old script after rw remount: 
 - just executing -

Remarks:

Setup of encrypted /home is shown here (use TOR; German only): http://mutant21.onastroidst6krpn.onion/schweinekraftland/Verschluesseln01/Verschluesselung_nachtraeglich_umsetzen.htm All file systems are ext4. It appears on several machines. Earliest identified OS rel. is Ubuntu 20.04 since mid of 2020.

mount version: util-linux 2.36 libmount 2.36.0

Looks to me like a bug, no doc found: If you remove the mount option "users" the problem will not occur. This must have changed mid 2020 since it definitely worked early 2020 to have option "users" and a mount with applied exec rights. Does not explain why "exec" option is just ignored when used in fstab the regular way.

Addendum:

mount version 2.34 does not show the error. Using mount version 2.36 causes the error, reproducible. Does not explain the bug but it explains the timeline of occurence.

permissions

0 Answers