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Let me preface this question with I am a Unix newbie and know just enough to get myself in trouble so treat me like an 8 year old :)
OS Ubuntu 20.04.2 LTS
Browser Firefox v85.0

Issue: Firefox does not seem to want to interact with File Explorer. Example: In Firefox I click on "File" then "Open file.." and literally nothing happens. So I opened a terminal that typed 'tail -f /var/log/syslog' then click "File" and "Open file.." and captured this output from syslog:

Feb  5 23:20:10 ubuntu kernel: [14806.739699] kauditd_printk_skb: 22 callbacks suppressed

Feb  5 23:20:10 ubuntu kernel: [14806.739706] audit: type=1400 audit(1612596010.047:234): apparmor="DENIED" operation="open" profile="snap.firefox.firefox" name="/run/mount/utab" pid=4462 comm="firefox-bin" requested_mask="r" denied_mask="r" fsuid=1000 ouid=0


Feb  5 23:20:10 ubuntu kernel: [14806.758367] audit: type=1107 audit(1612596010.067:235): pid=926 uid=103 auid=4294967295 ses=4294967295 msg='apparmor="DENIED" operation="dbus_method_call"  bus="system" path="/org/freedesktop/hostname1" interface="org.freedesktop.DBus.Properties" member="GetAll" mask="send" name=":1.160" pid=4462 label="snap.firefox.firefox" peer_pid=7830 peer_label="unconfined"
Feb  5 23:20:10 ubuntu kernel: [14806.758367]  exe="/usr/bin/dbus-daemon" sauid=103 hostname=? addr=? terminal=?'

Any clue what is happening or not happening?

Thank you!

Demonikhan
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    Your output shows that you are using the Firefox snap. Snaps are isolated by design, with only specific connections to the rest of the system permitted. The Firefox snap is allowed to see your /home directory, but nothing else. Your output shoes that the specific command denied is /run/mount/utab, which is mounting some other partition...which AppArmor considers to be outside your /home directory. – user535733 Feb 06 '21 at 12:44
  • Ok. I think I understand. Uninstall Firefox then go get Firefox directly from Mozilla. – Demonikhan Feb 06 '21 at 21:11
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    No: Uninstall the Firefox Snap. Then install the Firefox deb from the normal Ubuntu repositories. There is no need to go upstream to Mozilla (that's harder, and not necessary) – user535733 Feb 06 '21 at 21:16
  • Im sorry, but I dont understand. What does "Firefox deb" mean? What does "normal Ubuntu repositories" mean? – Demonikhan Feb 06 '21 at 21:20
  • I figured it out thanks to you. Thank you! I did the following: Uninstalled the snap Firefox via the snap store. Then ran 'sudo apt-get update' followed by 'sudo apt install firefox'. All fixed! Now all my menus work properly. – Demonikhan Feb 06 '21 at 22:30
  • This procedure doesn't work anymore as of ubuntu 22.04. Firefox can't be installed using apt get anymore (the firefox and chromium packages are now "transitional" packages). Does someone ( @user535733 ) have an answer that is up-to-date? Thanks! – adrian Apr 28 '22 at 15:05
  • See https://askubuntu.com/a/1399385/19626 for updated options. Keep in mind that the Search box at the top of the page can often provide faster answer to easy questions than waiting for a human to respond. – user535733 Apr 28 '22 at 19:21

1 Answers1

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I think you have had a Network Drive Connected, or an external Hard Drive/USB Drive.

Then you possibly unplugged it, or disconnected it. Firefox didn't take notice for some reason. Therefore Firefox complains that something is wrong with /run/mount/utab, where the temporary drive information (or info about the removal event, I don't know) was accessible.
Now it no longer isn't, and/or Firefox cannot read it properly. Or more likely, Firefox wants to read it but is not allowed to.

I think you can give Firefox explicit permission to read from /run/mount/utab by entering some information into file /etc/apparmor.d/local/usr.bin.firefox , which is empty by default.

more  /etc/apparmor.d/local/usr.bin.firefox

Content:

# Site-specific additions and overrides for usr.bin.firefox.
# For more details, please see /etc/apparmor.d/local/README.

Apparmor, a kernel module for Security, will then read these additional permissions.

However, I don't know how to do this either. The syntax is quite complicated.

knb
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