FireJail - Linux sandbox

Discussion in 'all things UNIX' started by Gitmo East, Oct 16, 2014.

  1. sthmptn

    sthmptn Registered Member

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    Here you are:

     
  2. summerheat

    summerheat Registered Member

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    @sthmptn : Just to clarify: without Firejail you are able to read and create/write files in /files?

    What's the output of groups ?
     
  3. sthmptn

    sthmptn Registered Member

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    Yes, that's correct; as soon as I issue 'firecfg --clean', I can read/write etc from this directory via LibreOffice. One thing to note is that even with Firejail active, I can still use programs such as Geany and KeepassXC sandboxed - I can read/write txt files etc via Geany and update a Keepass database on files. So this issue only /appears/ to be limited to LibreOffice (possibly the LibreOffice Firejail config.. but then you don't have the problem :doubt:)

    Thanks
     
  4. summerheat

    summerheat Registered Member

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    You can read/write files with those applications in your home directory - but in /files as well?
     
  5. sthmptn

    sthmptn Registered Member

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    Hello, and thanks for continuing with this. I'm aware that this may not be solvable but I appreciate your efforts!

    To check other apps, I did the following:

    Installed geany and keepassxc.

    Issued sudo firecfg and confirmed apps are firejailed:

    Created a keepass database in home, restarted app, added an entry, restarted and confirmed entry was written to db.

    Did the same as above for /files directory.

    Created txt files in Geany at both home and /files, saved, and confirmed editing is possible in both locations.

     
  6. summerheat

    summerheat Registered Member

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    @sthmptn : I have a suspicion: Can you write to /files with the firejailed LibreOffice if you add ignore apparmor to its profile?

    Background: The geany profile doesn't contain the apparmor rule - but the LIbreOffice profile does. Which means that it uses /etc/apparmor.d/firejail-default. And that one contains the following rule:
    Code:
    # Allow write access to paths writable in firejail which aren't used for
    # executing programs. /run, /proc and /sys are handled separately.
    # Line starting with /run/firejail/mnt/oroot deal with --overlay sandboxes.
    ##########
    /{,run/firejail/mnt/oroot/}{dev,etc,home,media,mnt,root,srv,tmp,var}/** w,
    which doesn't include /files.
     
  7. sthmptn

    sthmptn Registered Member

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    hmm. Maybe I've misinterpreted your instructions?

    Code:
    $ cd ~
    $ mkdir -p .config/firejail
    $ cd .config/firejail
    $ cp /etc/firejail/libreoffice.profile libreoffice.profile
    $ nano ~/.config/firejail/libreoffice.profile
    :: added to the end of the file: ignore apparmor
    $ sudo firecfg
    
    Below is the dialog box that appears when attempting to open the existing file.

    As soon as I run sudo firecfg --clean, the file opens without errors/dialog.


    upload_2020-5-26_15-11-30.png


    And this is when trying to save a new document to /files (with Firejail enabled) - in case you were wondering about the "document in use" notification - this file has not been saved yet..

    upload_2020-5-26_15-19-23.png
     
    Last edited: May 26, 2020
  8. summerheat

    summerheat Registered Member

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    The easiest way is that you delete ~/.config/firejail/libreoffice.profile and create a file libreoffice.local in that directory with just one entry: ignore apparmor

    EDIT: Of course, you could also simply comment apparmor in ~/.config/firejail/libreoffice.profile. But creating a .local file is simply easier in order to add or change rules in the upstream profile in /etc/firejail.

    EDIT2: See also these instructions.
     
    Last edited: May 26, 2020
  9. sthmptn

    sthmptn Registered Member

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    Hey, I was going to post last night when retesting but ran out of time.

    Good news! The instructions to remove existing and recreate a 'local' profile were successful. I tested in the VM and have no read/write problems within the directories.

    Code:
    $ rm .config/firejail/libreoffice.profile
    $ cd .config/firejail && echo ignore apparmor >> libreoffice.local
    
    BTW, I find the .local system much cleaner than recreating and editing the whole profile so thanks for that tip.

    Also, the link was informative; running firejail --noprofile libreoffice, allowed me to use LibreOffice without having to remove any Firejail configs (good for testing).

    Unfortunately my main system is still locking up whenever I try to add that local profile or even run with --noprofile. I can drop to the console via ctrl-alt+f2 but can't kill the processes and have to hard reset; the DE is just frozen with LibreOffice splashscreen. I'm going to start adding to the test VM to see what part of my set up causes this.

    Thank you ever so much for your help in solving this issue: Debian Buster > Apparmor > LibreOffice > Firejail = :sick:
     
  10. summerheat

    summerheat Registered Member

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    Good! So it's confirmed that /etc/apparmor.d/firejail-default was the culprit. I should have thought about that earlier - my aplogies.

    Yes, indeed. Btw., the reason why your first attempt didn't work was because an ignore ... rule must be located above the rule to be ignored in the respective profile. As the ...local files are included at the the top of each profile this makes sure that the rules therein take precedence.

    Regarding ignore apparmor: You can keep this modification, of course. However, that means that this additional protection will not be used in the LibreOffice profile. So a better alternative would be:
    1. In the file /etc/apparmor.d/local/firejail-local (which will not get overwritten by Firejail updates) you should add the rule
    Code:
    /{,run/firejail/mnt/oroot/}{dev,etc,home,media,mnt,root,srv,tmp,var,files}/** w,
    2. Consequence: Every firejailed application is now allowed to write to /files. If you don't want that I suggest to create the file ~/.config/firejail/globals.local and add the rule blacklist /files which effectively nullifies the change in 1. In order to make an exception for LibreOffice you just have to add noblacklist /files to libreoffice.local (and remove ignore apparmor).

    Or alternatively by executing it with the full path /usr/bin/libreoffice as this bypasses the respective symlink in /usr/local/bin.

    This is very weird, indeed. Have you searched in the logs by executing, e.g., journalctl -e | grep libreoffice or something like journalctl -e | grep -e failed -e Failed -e error -e Error -e ERROR -e DENIED -e denied -e failure -e Failure -e exception -e Exception when this happens?

    You're welcome :)
     
  11. sthmptn

    sthmptn Registered Member

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    Thanks for the additional information above. Once fixed, I'm going to add the apparmor rules as you suggest - happy for that location to be writable as it's archived to another location/device in any case.

    I found a thread (firejail forum) where users are having similar issues starting LibreOffice and someone also mentions the error I was getting when it did start, i.e. read-only access.

    https://github.com/netblue30/firejail/issues/1703

    I realise that my issue is specifically related to a directory outside of home and we've found the culprit but thought it may be useful info if anyone else having issues reads this. I came across this while searching for "Blacklist violations are logged to syslog", which is in my logs when starting LO from the console.

    As I get time, I'm going to go through the profile and gradually uncomment out all the options to see if I can start LO when firejailed.

    I'll update if I can find anything useful.
     
  12. vasa1

    vasa1 Registered Member

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  13. summerheat

    summerheat Registered Member

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    Here are my 2 or 3 cents:
    1. The notion that Firejail has a larger attack surface is probably related to the fact that Bubblewrap uses PR_SET_NO_NEW_PRIVS. Firejail doesn't use that by default - simply because specific applications (in particular Chromium-based browsers and VirtualBox don't start with it depending on unprivileged user namespaces being enabled in your distro-specific kernel or not). But you can manually enable it - which is what I do on my Arch Linux system (with the effect that VirtulaBox doesn't start with Firejail so it can "only" be confined by AppArmor. I'm using the Firejail git version, and this is the script I'm using to update it:
    Code:
    cd ~/firejail
    git pull
    ./configure --prefix=/usr --enable-apparmor
    make
    sudo make install
    
    sudo sed -i 's/# force-nonewprivs no/force-nonewprivs yes/' /etc/firejail/firejail.config
    sudo sed -i 's/# bind yes/bind no/' /etc/firejail/firejail.config
    sudo sed -i 's/# cgroup yes/cgroup no/' /etc/firejail/firejail.config
    sudo sed -i 's/# overlayfs yes/overlayfs no/' /etc/firejail/firejail.config
    
    sudo groupadd firejail
    sudo chown -c root:firejail /usr/bin/firejail
    sudo chmod -c 4750 /usr/bin/firejail
    sudo usermod -a -G firejail $USER
    
    sudo firecfg
    
    sudo rm /usr/local/bin/VirtualBox
    2. Bubblewrap is harder to use, IMO, and there are no ready-to-use profiles (although there are repositories which offer profiles for few applications). While Firejail offers 966 profiles right now which is certainly a big advantage. Most of those profiles contain the apparmor entry which means additional confinement by /etc/apparmor.d/firejail-default.

    3. The Bubblewrap github site says:
    I'm not sure what that means. Does that mean that whitelisting is not perfect - or does that mean that whitelisting introduces vulnerabilities?

    4. Regarding vulnerabilities: Firejail had its vulnerabilities, most of them in 2016/2017. It was still a rather new project then and has matured since then.
     
  14. SuperSapien

    SuperSapien Registered Member

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    Does anyone know if the development versions of Firejail supports the private home profile? firejail --private-home=.mozilla firefox
    The reason I ask is because I'm going to be installing Kubuntu 20.04 latter this year and it has the development version of Firejail in the software center (Discover Software Center) and when I installed the .deb file for the current version in
    VirtualBox the updater installed the development version. Also are there any security risk in using the development versions?
     
  15. summerheat

    summerheat Registered Member

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    Yes, it is. --private-home is not deprecated.

    No.
     
  16. SuperSapien

    SuperSapien Registered Member

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    Thanks I really appreciate. :):thumb:
     
  17. SuperSapien

    SuperSapien Registered Member

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    Is anyone having issues with add-ons being disabled in private-home with Firefox 80?
    firejail --private-home=.mozilla firefox
     
  18. Amanda

    Amanda Registered Member

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    Anyone able to start a private instance of Firefox lately?
    Firefox updated for me in the last few days, and now I can't start a private instance of it with:
    Code:
    firejail --private firefox -no-remote
    It just doesn't start at all.

    Kubuntu 20.04.2
     
  19. Rules

    Rules Registered Member

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    I don't use Firefox on my distro atm, but you could try to added these in your firefox profile, open pref.js and put
    Code:
    user_pref("extensions.autoDisableScopes", 0); + user_pref("extensions.enabledScopes", 15);
    If these already exist, replace-it

    Also you can try this command if the above fail : firejail --private-home=.mozilla firefox

    Rules.
     
  20. Amanda

    Amanda Registered Member

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  21. Rules

    Rules Registered Member

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