xrdp_channel_process failed error with chansrvport=DISPLAY(0)
#3237
Replies: 4 comments 14 replies
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This has been raised in a comment before by a user @usa- who now appears to have disappeared from Github. Most likely this is a regression. I'll try to get round to looking at it later today. |
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User @usa- asked me to tell you, that he hasn't disappeared, he sees everything, it's just that GitHub flagged his account for some unknown reason. That's why you temporarily (hopefully) can't see the tickets he created. |
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@es-fabricemarie - one thing springs to mind. Can you check your display number? If you've configured gdm on your machine for X operation only, display :0 will be used for gdm, and another display (probably :1) will be used for your session. Check your display number with You may need to set |
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Thanks for the help! I'm using sddm and not gdm. Yes the display number :0 seems correct as I do manage to get the sddm login window through RDP: I simply click ok on xrdp login window and xrdp shows me sddm login window. From there I can login as per usual. My issue is only with xrdp-chansrv. x0vncserver is started as root right after sddm, and xrdp-chansrv as root right after x0vncserver with the same DISPLAY and XAUTHORITY env variables. Does xrdp-chansrv require additional environment variables before being launched like that? |
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xrdp-chansrv needs to run as the same user as the X session. If you run it as root, |
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Sorry, that's I've opened #3240 on this to gather more information. |
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Thanks for the detailed explanation, this helps a lot. The directory exists and is populated (by chanserv) properly: I've tried to not start chanserv at all, and in that case the xrdp session simply fails completely. So it means chanserv seem to at least start properly. chanserv log file just says it closed the socket it opened earlier on: When I try on another machine where I configured xrdp in completely standard way with xvnc and dynamic sessions, I could see these files with lsof: Could the error messages I was seeing earlier on be related to sound? I'll try to simulate what https://github.com/neutrinolabs/pipewire-module-xrdp/blob/devel/instfiles/load_pw_modules.sh script does but at startup time since I want a static session. I'll get back shortly with the result. |
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I had a look at the code yesterday, and I'm not convinced that
As for the sound channels, these are only created when xrdp sends the channel list through from the client. Since we're not getting that connection, the channels won't be set up. |
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Thanks @matt335672 , this is progressing very well.
Let me fully disable spice (which might be hijacking the sound before xrdp does) and try again. If it doesn't work, I'll peer through all the logs and check what could be the issue. |
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I still get a tiny error (not sure if it's relevant), when I connect the RDP client to xrdp (but don't click ok yet in the xrdp blue screen to get the user session): This could be normal since I'm connecting to x0vncserver which is backed by Xorg on my real screen, I'm not sure. Before this last iteration, after I clicked "ok" to connect the session, I would get these logs: But now after making the |
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I managed to make it work in the end. I've added a export XRDP_SOCKET_PATH=/run/xrdp/0
export XRDP_PULSE_SOURCE_SOCKET=xrdp_chansrv_audio_in_socket_0
export XRDP_PULSE_SINK_SOCKET=xrdp_chansrv_audio_out_socket_0
export PULSE_SCRIPT=/etc/xrdp/pulse/default.pa
export XRDP_SESSION="blah"and I've changed my #!/bin/bash
XAUTHORITY=$(find /run/sddm/ -type f -name 'xauth_*')
export XAUTHORITY
export DISPLAY=:0
export USER=root
export HOME=/root
export XDG_CONFIG_DIRS=/root/.config/kdedefaults:/etc/xdg:/usr/share/kde-settings/kde-profile/default/xdg
export XDG_DATA_HOME=/root/.local/share
export LOGNAME=root
export KDE_SESSION_UID=0
export XDG_RUNTIME_DIR=/run/user/0
export XRDP_SESSION=1
sleep 2
# start the VNC server
/usr/bin/x0vncserver \
--display=:0 \
--rfbauth=/etc/entsecure/vncpasswd \
--rfbport=5900 \
--localhost \
--AlwaysShared &
# ensure all your users are part of the "users" group, or choose the correct one.
# create the directory in advance and add set-gid to the directory
# so regular users can connect
mkdir -p /run/xrdp/0
chown root:users /run/xrdp/0
chmod g+s /run/xrdp/0
/usr/sbin/xrdp-chansrvFinally, I deleted the I haven't tried copy/paste and USB redirections yet, but sounds work. |
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That's great. If sound is working you should be there for the other chansrv functions. The error is coming about as xrdp is trying to open a channel to the client to get dynamic updates. This is clearly pointless in your configuration. Can you add the following to your Sorry I missed your stanza earlier - I can see it now:- [Xvnc]
name=default
lib=libvnc.so
username=
password=password
ip=127.0.0.1
port=5900
chansrvport=DISPLAY(0)In the move to v0.10.x we improved the socketdir security quite a bit, Consequently, the In your somewhat unusual setup, there's no user and no authentication, so the DISPLAY() mechanism is silently failing. This needs improvement. My current thinking is:-
I also need to give chansrv a way to create the socket dir if it doesn't exist, (although this doesn't apply to your setup). Because of the permissions involved, it's likely chansrv will need to ask sesman to do this. I'd appreciate any thoughts you have on this, particularly as you're coming at it from a completely different angle - I've probably missed something else somewhere. |
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This indeed removes the error, thanks: I agree with your recommendations on logging and directory creation, yes. My main issue in a nutshell is that since I'm doing xrdp before user authentication (and don't use sesman+rdp+pam for auth) my chansrv process has to be owned by root. chansrv doesn't give me issues with sound redirection, as I handle the file permission of the xrdp socket dir and grant group permission. But it does give issues with other redirections. In my current config for example, drives "sharing" from windows will mount the drives over at: And all the files in there are owned by root. Which makes it impossible for a non-privileged user to access. I've since enabled vsocket in the xrdp.ini config file and made the daemon listen to vsocket and tcp: I'm now seeing this error when I test the redirections further: Which I have no idea how to interpret for now. But I'm happy to help debug them. To solve the issues I'm facing, I was thinking if there were a way that I could run the main chansrv process as root as I do now, but start a sub-chansrv process from the non-privileged user's session (for example with xdg autostart mechanism) in a way that they talk to each other? I don't manage to make it work right now as there seem to be some shared secret/knowledge between the two? I've noticed there is a Any idea if that is possible? |
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I don't know if the kernel will let you share FUSE devices in this way, so that may not be possible. However, you can play with these options in sesman.ini and see if they can solve this for you:-
The errors you list are (surprisingly) perfectly normal. See #2040 for the background. We've got no provision for chaining chansrv processes, but it's an interesting idea! It would be horribly slow however, and I've no idea how we could make the permissions work in a sane way.
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For the errors mentioned in 2040 thanks, that explains everything and makes a lot of sense.
What I meant was not really chaining chansrv processes, but more like take-over when there is an (external to sesman) user session started. So it would be something like this: root chansrv running (no user logged in) Then when user logs out That would complicate things a bit initially but makes a lot of sense on some setups (like mine) |
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Let's crack on with seeing if we can solve your existing chansrv issues first with |
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I'm trying to get xrdp to connect statically to a x0vncserver session running on the main Xorg process. The goal is for a single user to connect via xrdp to the console running sddm, without having to enter a password in xrdp dialog.
The console and xrdp should show the same screen in the same state.
I'm using xrdp version 0.10.1 on Fedora 40.
My machine has the standard systemd sddm-x11 service running on the machine, where it starts an Xorg instance and awaits user login. I've made a systemd service to start x0vncserver for that display (after sddm service has started), as well as run xrdp-chansrv right after that. I've configured xrdp.ini to statically use that session.
The user can indeed connect and get the sddm screen after launching an RDP client and pressing enter on the xrdp login dialog.
The user can then proceed to login with sddm and and get a normal KDE session that just works.
My problem is with chansrv, xrdp doesn't seem to manage to connect to it. So all the channel operations like sound redirection, usb redirection etc do not work. When I run
lsofto inspect the xrdp-chansrv process, I don't see any Unix sockets (that I can usually see in a more standard configuration of xrdp)Am I missing some configuration or parameter when I start xrdp-chansrv?
The service I use to start x0vncserver is
The file
/usr/libexec/start_vnc0contains:My
/etc/xrdp/xrdp.inicontains:My
/etc/xrdp/sesman.inifile is:sesman log file is almost empty and doesn't look relevant here.
xrdp log file is:
After I disconnect the session, xrdp.log adds these lines:
I was following the hints from #1891 (comment)
given by @matt335672 regarding
chansrvport=DISPLAY(0)but I seem to be missing something.Beta Was this translation helpful? Give feedback.
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