Removing need for passwordless sudo for OSMC user

sam_nazarko · 22 August 2016 11:22

Not really.There are dozens of other ways to escalate to a privileged shell anyway. You should always be wary of what you install on your system.

Passworded sudo does not protect against this. At best it gives users a moment to think about what they’re doing and guards their system from brief moments of being unattended.

And passwordless sudo is only granted for the OSMC user, so for example, one cannot escalate this way.

Getting the balance right can be tricky but I think we have it right.

We could probably move back to a passworded sudo mechanism by changing the watchdog script for Kodi. We can set CAPS via systemd and rework the script, but this is low on the list. Kodi doesn’t really need sudo rights. This is where it’s used:

github.com

osmc/osmc/blob/master/package/mediacenter-osmc/patches/rbp2-watchdog#L87


      
                  dialog --backtitle "Package configuration" --title "OSMC Update" --infobox "\n         Updating the list of available OSMC packages..." 5 71 > /dev/tty1
                  err=$(apt-get -qq update); if [ -n "$err" ]
                  then
                          dialog --backtitle "Package configuration" --title "OSMC Update" --infobox "The following errors occured while searching for new packages:\n\n${err}\n\nContinuing in 20 seconds..." 0 0 > /dev/tty1
                          sleep 20
                  fi
                  systemctl start manual-update
                  exit 0
                  ;;
          esac
          
          if [ ! -e /var/run/fb_resolution ]; then
          	/bin/fbset | grep geometry | awk '{print "-xres "$2" -yres "$3" -vxres "$4" -vyres "$5}' > /var/run/fb_resolution
          fi
          
          if [ $root_space -lt 100 ]; then
          	set_font
          	dialog --infobox "\n            WARNING! Free disk space remaining is only ${root_space}MB.\n\nKodi will be unable to start if disk space is completely exhausted. Please free sufficient disk space as soon as possible. Continuing in 10 seconds..." 8 80 > /dev/tty1
          	sleep 10
          fi

But then you need to think about how we allow changes to hostname, changes to timezone and other system settings. This is added by OSMC, and it’s not easy to make these system changes without temporarily elevating permissions.

I’ll accept a PR to change the behaviour, if you’re willing to work on it.

It’s not as interesting as you think. Just a standard sandboxing mechanism. The attack surface is very low currently, after the changes it should be non-existent.