[SOLVED] KDE Plasma notifications from cron

stormtracknole · 03-22-2021, 05:59 AM

Greetings!

I am running into an issue with running a cron that uses notify-send. This scripts works on Gnome and XFCE. For whatever reason, I cannot get it to work on KDE Plasma (-current 5.21.3). From what I have been able to research, it seems to be related to DBUS_SESSION_BUS_ADDRESS not being set. I have tried all sorts of different variations to no avail. Even setting the DISPLAY value doesn't seem to work.

Any thoughts as to what else I am missing? Thanks!

Tonus · 03-22-2021, 06:09 AM

Show script for us to suggest something

stormtracknole · 03-22-2021, 06:18 AM

Quote:

Originally Posted by Tonus

Show script for us to suggest something

Code:

#!/bin/bash

DISPLAY=:1

notify-send -u critical "Remember to check for precip."

It doesn't work in Wayland or with Xorg. I thought it might have been a Wayland thing. This same script works with XFCE in Slackware and Fedora Gnome.

LuckyCyborg · 03-22-2021, 06:40 AM

Quote:

Originally Posted by stormtracknole

Code:

#!/bin/bash

DISPLAY=:1

notify-send -u critical "Remember to check for precip."

It doesn't work in Wayland or with Xorg. I thought it might have been a Wayland thing. This same script works with XFCE in Slackware and Fedora Gnome.

I believe that your "issue" is of completely another nature.

In fact, you just demonstrate that there is a HUGE security issue on XFCE or even Fedora's GNOME, which permits to another user (i.e. the one used by CRON) to send notifications to another user desktop - so, I can imagine someone defacing somehow the "nobody" account then bombing everybody logged in the box with Viagra advertising on desktop popups.

Also, you just demonstrate that KDE Plasma5 has a superior security, and it is NOT VULNERABLE to this particular security issue.

I suggest you to not rely your work on existence of this particular security issue, which probably will be fixed sooner or later by the XFCE and GNOME developers.

stormtracknole · 03-22-2021, 06:45 AM

Quote:

Originally Posted by LuckyCyborg

I believe that your "issue" is of another nature.

In fact, you just demonstrate that there is a HUGE security issue on XFCE or even Fedora's GNOME, which permits to another user (i.e. the one used by CRON) to send notifications to another user desktop - so, I can imagine someone defacing somehow the "nobody" account then bombing everybody logged in the box with Viagra advertising on desktop popups.

Also, you just demonstrate that KDE Plasma5 has a superior security, and it is NOT VULNERABLE at this particular security issue.

I suggest you to not rely your work on existence of this particular security issue, which probably will be fixed sooner or later by the XFCE and GNOME developers.

I'm running the cron as my own user while I'm logged in. I don't see how this would be a problem.

LuckyCyborg · 03-22-2021, 06:52 AM

Quote:

Originally Posted by stormtracknole

I'm running the cron as my own user while I'm logged in. I don't see how this would be a problem.

This is a very important information, you should have been specified.

Then, you need to have somehow an DBUS session started on every console, for this to work with Plasma5.

You can look for the threads regarding PipeWire about our tries to use a DBUS SESSION on the systemd style, started at a whatever user login.

It's not that simple, so IF you do not need that for a greater scope (like running the PipeWire daemons on console), probably better leave at how it is.

gegechris99 · 03-22-2021, 06:55 AM

Look at this thread how-to-use-slackpkg-check-updates-in-a-script for a way to get and set DBUS_SESSION_BUS_ADDRESS in a script before calling notify-send.

Code:

#!/bin/bash
/usr/bin/mkdir -p ~/.slackpkg
/usr/sbin/slackpkg check-updates | /usr/bin/sed -n '/available/ p' > ~/.slackpkg/updated-repo.txt
username=$(/usr/bin/whoami)
#pid=$(pgrep -u $username kded5)
pid=$(ps -u $username e | grep -m 1 DBUS_SESSION_BUS_ADDRESS | awk '{print $1}')
dbus=$(grep -z DBUS_SESSION_BUS_ADDRESS /proc/$pid/environ | sed 's/DBUS_SESSION_BUS_ADDRESS=//')
export DBUS_SESSION_BUS_ADDRESS=$dbus
[ -s ~/.slackpkg/updated-repo.txt ] && /usr/bin/notify-send -i dialog-warning "[ S L A C K P K G ]" "Available updates"

stormtracknole · 03-22-2021, 07:02 AM

Quote:

Originally Posted by gegechris99

Look at this thread how-to-use-slackpkg-check-updates-in-a-script for a way to get and set DBUS_SESSION_BUS_ADDRESS in a script before calling notify-send.

Code:

#!/bin/bash
/usr/bin/mkdir -p ~/.slackpkg
/usr/sbin/slackpkg check-updates | /usr/bin/sed -n '/available/ p' > ~/.slackpkg/updated-repo.txt
username=$(/usr/bin/whoami)
#pid=$(pgrep -u $username kded5)
pid=$(ps -u $username e | grep -m 1 DBUS_SESSION_BUS_ADDRESS | awk '{print $1}')
dbus=$(grep -z DBUS_SESSION_BUS_ADDRESS /proc/$pid/environ | sed 's/DBUS_SESSION_BUS_ADDRESS=//')
export DBUS_SESSION_BUS_ADDRESS=$dbus
[ -s ~/.slackpkg/updated-repo.txt ] && /usr/bin/notify-send -i dialog-warning "[ S L A C K P K G ]" "Available updates"

Very nice!! Thank you. I'll try that and report back.

Quote:

Originally Posted by LuckyCyborg

This is a very important information, you should have been specified.

Then, you need to have somehow an DBUS session started on every console, for this to work with Plasma5.

You can look for the threads regarding PipeWire about our tries to use a DBUS SESSION on the systemd style, started at a whatever user login.

It's not that simple, so IF you do not need that for a greater scope (like running the PipeWire daemons on console), probably better leave at how it is.

You are right. My apologies for that. I blame the fact that it is still early in the morning where I live and I have yet to have my coffee.

stormtracknole · 03-22-2021, 07:45 AM

Well, no matter what option I use, notify-send nor kdialog works. I even tried all the options in that thread. The script works fine of course when running from a terminal. I'm pretty stumped. This shouldn't be this difficult. :/

gegechris99 · 03-22-2021, 08:02 AM

Can you publish your script as well as the result of "crontab -l"?
Thanks.

Chuck56 · 03-22-2021, 08:05 AM

My sendmail server uses a procmail initiated script that notifies both Plasma/KDE5 desktop & Android phone for inbound email.

Here's the desktop function from the script:

Code:

desktop () {

  # local variables & arrays
  declare notify

  # args: [1]from [2]subject [3]user [4]system
  # use dbus, not display, sample:
  # DBUS_SESSION_BUS_ADDRESS=unix:abstract=/tmp/dbus-fO9P532lUo
  # ,guid=e39481e97ebfba51d679a1295ef5e9f5
  # get dbus-session & notify over ssh
  notify="dbus=\$(ps -u $3 -o cmd e \
    | grep '^/usr/bin/kded5' \
    | tr ' ' '\n' \
    | grep DBUS_SESSION_BUS_ADDRESS)
    export \$dbus
    notify-send -a Sendmail -t 10000 '$1' '$2'"
  bash_print "$notify" | ssh $3@$4 'bash -s'

  unset -f $FUNCNAME # unload function
} # END desktop

Hope that helps.

stormtracknole · 03-22-2021, 08:50 AM

Ugh, my mistake.

Using:

Code:

username=$(/usr/bin/whoami)
export DBUS_SESSION_BUS_ADDRESS=$(ps -u $username e | grep -Eo 'dbus-daemon.*ADDRESS=unix:abstract=/tmp/dbus-[A-Za-z0-9]{10}' | tail -c35)

worked. I forgot to add export the first time around. Now this is working as intended. Thank you all for the help!

stormtracknole · 03-22-2021, 09:02 AM

One more thing that I should note is that kdialog does not work even with this environment. Only notify-send does. Perhaps kdialog requires some extra bit of configuration. Just wanted to note that for future reference.

0XBF · 03-22-2021, 09:32 PM

The way plasma is launched in slackware is incorrect imo and fails to set DBUS_SESSION_BUS_ADDRESS properly on launch. Its done correctly for xfce so thats why that works, no idea what happens in gnome because I'm not using that at the moment.

If you are launching plasma from init 3 you can edit your ~/.xinitrc file to correct the behaviour. Look for the line

Code:

dbus-launch --sh-syntax --exit-with-session startplasma-x11

and change it to

Code:

dbus-run-session startplasma-x11

or

Code:

eval `dbus-launch --sh-syntax --exit-with-session startplasma-x11`

or even

Code:

/usr/lib64/plasma-dbus-run-session-if-needed startplasma-x11

Any of the above will set the DBUS_SESSION_BUS_ADDRESS environment variable properly. The problem is that "dbus-launch --sh-syntax" echos syntax to set the DBUS_SESSION_BUS_ADDRESS when it completes but that still requires the "eval" to actually set it. The alternative dbus-run-session command does the same thing and sets the variable automatically. The last command checks if theres already a dbus and uses dbus-run-session if it needs to.

Same problem is in the wayland launching script "/usr/bin/startkwayland", you can apply the same fix there. Also applies to the init 4 lanuch of x11 plasma in " /usr/share/xsessions/plasma.desktop". Whichever you use just fix it there. Then you shouldn't have to resort to hacks to get the DBUS_SESSION_BUS_ADDRESS variable.

Been fixing this for a while now in my installs, hoping to see it fixed in slackware 15...

stormtracknole · 03-23-2021, 05:25 AM

Quote:

Originally Posted by 0XBF

The way plasma is launched in slackware is incorrect imo and fails to set DBUS_SESSION_BUS_ADDRESS properly on launch. Its done correctly for xfce so thats why that works, no idea what happens in gnome because I'm not using that at the moment.

If you are launching plasma from init 3 you can edit your ~/.xinitrc file to correct the behaviour. Look for the line

Code:

dbus-launch --sh-syntax --exit-with-session startplasma-x11

and change it to

Code:

dbus-run-session startplasma-x11

or

Code:

eval `dbus-launch --sh-syntax --exit-with-session startplasma-x11`

or even

Code:

/usr/lib64/plasma-dbus-run-session-if-needed startplasma-x11

Any of the above will set the DBUS_SESSION_BUS_ADDRESS environment variable properly. The problem is that "dbus-launch --sh-syntax" echos syntax to set the DBUS_SESSION_BUS_ADDRESS when it completes but that still requires the "eval" to actually set it. The alternative dbus-run-session command does the same thing and sets the variable automatically. The last command checks if theres already a dbus and uses dbus-run-session if it needs to.

Same problem is in the wayland launching script "/usr/bin/startkwayland", you can apply the same fix there. Also applies to the init 4 lanuch of x11 plasma in " /usr/share/xsessions/plasma.desktop". Whichever you use just fix it there. Then you shouldn't have to resort to hacks to get the DBUS_SESSION_BUS_ADDRESS variable.

Been fixing this for a while now in my installs, hoping to see it fixed in slackware 15...

Nice!! Thank you for pointing this out.