Thank you for your elaborate explanations, both of you :) My late response is only because it has taken some time for me to poke around in systemd and other relevant parts of Linux, to get a better understanding.
I have now created an issue: https://github.com/microsoft/WSL/issues/10896, where I think it belongs. The validate_runtime_directory in pam_systemd already does a number of checks on XDG_RUNTIME_DIR. To me it seems appropriate if it also verified the permissions to be 700. Do you agree? That would cause a warning (which is a help to the developers) when something/someone violates the specifications. On Wed, Nov 29, 2023 at 10:51 PM Mantas Mikulėnas <graw...@gmail.com> wrote: > On Wed, Nov 29, 2023, 20:59 Thomas Larsen Wessel <mrve...@gmail.com> > wrote: > >> Thanks both of you! :) >> >> I have taken some time to digest your answers. And in particular I have >> tried to investigate this line closer: >> >> *Nov 27 12:34:22 tumbleweed unknown: WSL (2): Creating login session for >> andrei* >> >> I have found the equivalent log line on my WSL Ubuntu. I was hoping I >> could find out more about where its coming from; ie which process / service >> prints this. But journalctl does not tell me much about the origin. >> >> >> >> >> >> >> >> >> >> >> *journalctl -b --grep "Creating login session for velle" -o verboseWed >> 2023-11-29 18:41:19.982271 CET >> [s=d318bdab5d1f4ad7a48a947e6fff4a01;i=2d53;b=c8682ff139cf40da8326fd63d7c34d7c;m=1649> >> _TRANSPORT=kernel _MACHINE_ID=967980c77d4743298ceaeb5d512bf388 >> _HOSTNAME=ELCON45223 PRIORITY=6 SYSLOG_FACILITY=1 MESSAGE=WSL (2): >> Creating login session for velle >> _BOOT_ID=c8682ff139cf40da8326fd63d7c34d7c >> _SOURCE_MONOTONIC_TIMESTAMP=23368229* >> >> Most log entries in journalctl has a _PID field, but some don't, and this >> one does not. Why? What does it tell, that a log entry has no _PID? As far >> as I know ever process has an PID, even systemd itself has a PID (which is >> always 1). Or am I wrong about that? I see now reason why those PIDs are >> not saved together with the log entries. >> > > According to _TRANSPORT the message went through the kernel log (dmesg), > i.e. it was either kernel-generated (no PID) or it was written by the > process to /dev/kmsg (PID information not preserved) rather than being sent > the usual way through syslog. There might have been a PID but journald had > no way to obtain it. > > That aside, another thing about WSL2 is that the entire VM actually boots > a "system distro" first and the user-facing Ubuntu distro is started as a > container. So there are several processes that run within the VM but exist > outside of the container's PID namespace and therefore don't have PIDs from > the Ubuntu container's PoV; only the "host" namespace has PIDs for them. > > (Consider how a container's "PID 1" looks from outside the container...) > > > >> >> >> On Mon, Nov 27, 2023 at 10:37 AM Andrei Borzenkov <arvidj...@gmail.com> >> wrote: >> >>> On Mon, Nov 27, 2023 at 1:06 AM Thomas Larsen Wessel <mrve...@gmail.com> >>> wrote: >>> >> >>> >> WSL does not use systemd by default. >>> > >>> > >>> > According to this article, it systemd has been default on WSL Ubuntu >>> since june 2023. https://learn.microsoft.com/en-us/windows/wsl/systemd >>> > >>> > "Systemd is now the default for the current version of Ubuntu that >>> will be installed using the wsl --install command default." >>> > >>> > Also when I look in the /var/log/auth.log, there are many lines with >>> systemd, e.g.: >>> > >>> > Nov 25 22:30:14 ELCON45223 systemd-logind[155]: New session 6 of user >>> velle. >>> > Nov 25 22:30:14 ELCON45223 systemd: pam_unix(systemd-user:session): >>> session opened for user velle(uid=1000) by (uid=0) >>> > >>> > Could someone please help me understand exactly which part creates >>> this XDG_RUNTIME_DIR folder? >>> >>> /run/user/$UID for the "console" session (the one you get when >>> starting a WSL instance) is created by WSL before systemd. Adding "ls >>> -l /run/user" to user-runtime-dir@1000.service ExecStartPre: >>> >>> Nov 27 12:34:22 tumbleweed unknown: WSL (2) ERROR: >>> WaitForBootProcess:3237: /sbin/init failed to start within 10000 >>> Nov 27 12:34:22 tumbleweed unknown: ms >>> Nov 27 12:34:22 tumbleweed unknown: WSL (2): Creating login session for >>> andrei >>> ... >>> Nov 27 12:34:22 tumbleweed systemd[1]: Created slice User Slice of UID >>> 1000. >>> Nov 27 12:34:22 tumbleweed systemd[1]: Starting User Runtime Directory >>> /run/user/1000... >>> Nov 27 12:34:22 tumbleweed ls[520]: total 0 >>> Nov 27 12:34:22 tumbleweed ls[520]: drwxr-xr-x 4 andrei users 120 Nov >>> 27 12:34 1000 >>> Nov 27 12:34:22 tumbleweed systemd-logind[160]: New session 11 of user >>> andrei. >>> Nov 27 12:34:22 tumbleweed systemd[1]: Finished User Runtime Directory >>> /run/user/1000. >>> >>> So logind invokes user-runtime-dir@1000.service, but it sees the >>> existing directory and does nothing. I would suggest asking this >>> question on WSL support channels. >>> >>> > Is it part of the systemd repo or not? And if the answer is (or may >>> be) different between Ubuntu and WSL Ubuntu, I would be happy if you share >>> what you know about any any of those cases :) Right now, I barely know >>> where to report this issue. >>> > >>> > >>> > On Sun, Nov 26, 2023 at 10:07 AM Andrei Borzenkov <arvidj...@gmail.com> >>> wrote: >>> >> >>> >> On 26.11.2023 02:39, Thomas Larsen Wessel wrote: >>> >> > I set up WSL on Windows 10 and created an instance from the default >>> Ubuntu >>> >> > 22.04 image. >>> >> > >>> >> > I ran some (non-GUI) software that somehow relies on Qt, and >>> apparently Qt >>> >> > does some checks on the XDG environment, so I got the following. >>> >> > >>> >> > *Warning: QStandardPaths: wrong permissions on runtime directory >>> >> > /run/user/1000/, 0755 instead of 0700* >>> >> > >>> >> > And yes, all the user folders are set to 755, including much of >>> their >>> >> > content, which violates the XDG Base Directory Specification. >>> (screenshot: >>> >> > https://i.imgur.com/ISn3ebh.png). >>> >> > >>> >> > As far as I can understand, its some part of systemd, that creates >>> this >>> >> > folder. So is this an issue with systemd? >>> >> > >>> >> >>> >> WSL does not use systemd by default. >>> >> >>> >> > The validate_runtime_directory in pam_systemd already does a number >>> of >>> >> > checks on XDG_RUNTIME_DIR. How about also checking if the >>> permissions are >>> >> > correct/valid? >>> >> > >>> >> > Sincerely, Thomas >>> >> > >>> >> >>> >>