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A bunch of things on a modern desktop linux system depend on it. Disregard what the user you replied to said, as polkit is a system to delegate elevated permiss

by mhitza 5y ago

A bunch of things on a modern desktop linux system depend on it. Disregard what the user you replied to said, as polkit is a system to delegate elevated permission grants from GUI applications. A GUI sudo if you will, with XML and javascript code for its configuration files. I'm not near my computer, but I would guess pipewire (as it usually runs within the users session) might rely on it to access the sound hardware without needing to run as root. But just guessing.

foxfluff 5y ago
The only things on my system that depend on it are pipewire and xorg-x11-drv-intel (which I don't need). It doesn't sound like you should need a GUI sudo with XML and Javascript for audio..
- 0xbadcafebee 5y ago
  It does appear to exist solely to let users use their own local hardware: https://wiki.debian.org/PolicyKit https://wiki.debian.org/PolicyKit PolicyKit is an application-level toolkit for defining and handling the policy that allows unprivileged processes to speak to privileged processes, in order to grant some user the right to perform some tasks in some situations. It is sometimes referred to as "the sudo of systemd". Sample uses: Let the user Hibernate and shutdown the computer. Let the user manage (Wireless) connections. Let the user mount/eject a removable media (CD/DVD, USB keys...) Let the user access devices, like audio, scanner, etc. We already had a solution for this before: you add the user to the 'audio' group. And SELinux could do this too. But apparently RedHat just wanted another layer (https://lwn.net/Articles/258592/ https://lwn.net/Articles/258592/). "This is better than groups and setgid processes, because it means someone can't log in over ssh and mess with another user at the console." - Because that's what desktop users are really concerned about. We need more complexity because somebody might hax0r my desktop over SSH. And, wow, they really actually did use XML as their configuration: <match action="org.freedesktop.hal.storage.mount-fixed"> <match user="davidz"> <return result="yes"/> </match> <match user="freddy"> <return result="no"/> </match> </match> So, not only is it superfluous, it also doesn't make the user's life easier, it's super annoying to configure, everything depends on it, and now the thing intended to improve security has caused a security issue.
  - throwawaysysd 5y ago
    Creating another group every time and asking the sysadmin to add you to the group when you want a new permission is not an appropriate solution for the desktop. It also isn't fine grained (what if you want to only grant permission to one audio device, then you'll need to create lots of audio groups and keep track of them all) and doesn't handle the case where you want to temporarily grant privileges to some device for just one session. There is more to it than just the issue with ssh, and it's not superfluous. There is a very good reason desktops all use it.
    - throwaway984393 5y ago
      What sysadmin are desktop users having to ask for permission to use their own hardware? Even in 2001, if you had a laptop, you had access to use all it's hardware. Why wouldn't you? How many groups do you think there are? There's only so many classes of hardware, so there's only so many groups. About 8 in total. You add the user to all of them at once. It worked just fine before polkit arrived. Why would you want to temporarily grant privileges to hardware once? Who is trying to prevent the user from using their own hardware? What's the very good reason all desktops use it?
      - throwawaysysd 5y ago
        I detailed this in another comment, the reason desktops use it is to get those macOS-style permission dialogs that pop up when you try to take some privileged action. I don't think any desktop distribution wants to ask users to open a terminal and type "sudo usermod" and then log out and log back in in order to do something like setting the clock or formatting a usb drive. I don't remember this working well at all before polkit arrived either, I remember when device hotplug in Linux was really broken for this reason (and a few others). It's not reasonable to ask desktop users to edit udev rules when plugging in a new device. If it worked well at all it was because you were doing things like having a lot of suid/sgid tools or just running GUI programs as root which is a terrible idea. >Who is trying to prevent the user from using their own hardware? I don't understand this question. The functionality here is equivalent to sudo, you type your password to authenticate a certain action. As the sysadmin you can configure some actions to always accept or always deny, if you want.
xorcist 5y ago
> A GUI sudo if you will, with XML and javascript code for its configuration files. Sounds great! What could possibly go wrong?

by mhitza 5y ago

foxfluff 5y ago

The only things on my system that depend on it are pipewire and xorg-x11-drv-intel (which I don't need). It doesn't sound like you should need a GUI sudo with XML and Javascript for audio..

0xbadcafebee 5y ago
It does appear to exist solely to let users use their own local hardware: https://wiki.debian.org/PolicyKit https://wiki.debian.org/PolicyKit PolicyKit is an application-level toolkit for defining and handling the policy that allows unprivileged processes to speak to privileged processes, in order to grant some user the right to perform some tasks in some situations. It is sometimes referred to as "the sudo of systemd". Sample uses: Let the user Hibernate and shutdown the computer. Let the user manage (Wireless) connections. Let the user mount/eject a removable media (CD/DVD, USB keys...) Let the user access devices, like audio, scanner, etc. We already had a solution for this before: you add the user to the 'audio' group. And SELinux could do this too. But apparently RedHat just wanted another layer (https://lwn.net/Articles/258592/ https://lwn.net/Articles/258592/). "This is better than groups and setgid processes, because it means someone can't log in over ssh and mess with another user at the console." - Because that's what desktop users are really concerned about. We need more complexity because somebody might hax0r my desktop over SSH. And, wow, they really actually did use XML as their configuration: <match action="org.freedesktop.hal.storage.mount-fixed"> <match user="davidz"> <return result="yes"/> </match> <match user="freddy"> <return result="no"/> </match> </match> So, not only is it superfluous, it also doesn't make the user's life easier, it's super annoying to configure, everything depends on it, and now the thing intended to improve security has caused a security issue.
- throwawaysysd 5y ago
  Creating another group every time and asking the sysadmin to add you to the group when you want a new permission is not an appropriate solution for the desktop. It also isn't fine grained (what if you want to only grant permission to one audio device, then you'll need to create lots of audio groups and keep track of them all) and doesn't handle the case where you want to temporarily grant privileges to some device for just one session. There is more to it than just the issue with ssh, and it's not superfluous. There is a very good reason desktops all use it.
  - throwaway984393 5y ago
    What sysadmin are desktop users having to ask for permission to use their own hardware? Even in 2001, if you had a laptop, you had access to use all it's hardware. Why wouldn't you? How many groups do you think there are? There's only so many classes of hardware, so there's only so many groups. About 8 in total. You add the user to all of them at once. It worked just fine before polkit arrived. Why would you want to temporarily grant privileges to hardware once? Who is trying to prevent the user from using their own hardware? What's the very good reason all desktops use it?
    - throwawaysysd 5y ago
      I detailed this in another comment, the reason desktops use it is to get those macOS-style permission dialogs that pop up when you try to take some privileged action. I don't think any desktop distribution wants to ask users to open a terminal and type "sudo usermod" and then log out and log back in in order to do something like setting the clock or formatting a usb drive. I don't remember this working well at all before polkit arrived either, I remember when device hotplug in Linux was really broken for this reason (and a few others). It's not reasonable to ask desktop users to edit udev rules when plugging in a new device. If it worked well at all it was because you were doing things like having a lot of suid/sgid tools or just running GUI programs as root which is a terrible idea. >Who is trying to prevent the user from using their own hardware? I don't understand this question. The functionality here is equivalent to sudo, you type your password to authenticate a certain action. As the sysadmin you can configure some actions to always accept or always deny, if you want.

xorcist 5y ago

> A GUI sudo if you will, with XML and javascript code for its configuration files. Sounds great! What could possibly go wrong?