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Zucca
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Location: Rasi, Finland
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 Posted: Sat Jun 12, 2021 3:29 pm Post subject: What's reponsible of creating /run/user/<UID> |
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On my OpenRC based system I only have directory 0 for root, but nothing for other users.
Which program is responsible for creating all the user directories under /run/user/? Some programs assume those user directories are created and will fail if there's none.
Do others have similar problems?
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Anon-E-moose
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| Posted: Sat Jun 12, 2021 3:44 pm Post subject: |
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Nope. 
Edit to add: but then again I'm running an old (ancient?) version of openrc.
As far as the run dir, gnome takes care of it when it's running, I believe that kde does also, and maybe some of the dm's might.
Me, I just manually created mine over in /tmp, not /run (personal choice) and set XDG_RUNTIME_DIR=<dir name> appropriately.
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Last edited by Anon-E-moose on Sat Jun 12, 2021 3:48 pm; edited 1 time in total |
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GDH-gentoo
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| Posted: Sat Jun 12, 2021 3:48 pm Post subject: Re: What's reponsible of creating /run/user/<UID> |
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| Zucca wrote: | | Which program is responsible for creating all the user directories under /run/user/? |
elogind, through PAM, when the corresponding user logs in.
Last edited by GDH-gentoo on Sat Jun 12, 2021 3:49 pm; edited 1 time in total |
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Anon-E-moose
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| Posted: Sat Jun 12, 2021 3:49 pm Post subject: Re: What's reponsible of creating /run/user/<UID> |
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| GDH-gentoo wrote: | | Zucca wrote: | | Which program is responsible for creating all the user directories under /run/user/? |
elogind, through PAM, when the corresponding user logs in. |
Nice to know. Not that I'm running *logind
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Zucca
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| Posted: Sun Jun 13, 2021 12:13 pm Post subject: |
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Hm... The program I have problems with is dte. It tries to create lock file under /run/user/$UID and if the directory is missing then it opes files ro.
I smell a bug.
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| My gentoo installs: | init=/sbin/openrc-init
-systemd -logind -elogind seatd |
| Quote: | | I am NaN! I am a man! |
Last edited by Zucca on Sun Jun 13, 2021 1:40 pm; edited 1 time in total |
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Naib
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| Posted: Sun Jun 13, 2021 12:20 pm Post subject: |
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| Quote: | export XDG_RUNTIME_DIR=$(mktemp -d /tmp/$(id -u)-runtime-dir.XXX)
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it will be a program explicitly wanting to write to XDG_RUNTIME_DIR with no ~/ fallback.
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javeree
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| Posted: Sun Jun 13, 2021 3:14 pm Post subject: |
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@GDH-gentoo
Does that mean
* you login, this calls pam and pam calls logind
or
* you login, logind gets called (how?) and logind calls pam
?
I don't quite understand the role of logind, neither in what exactly it does nor whwhat it gets triggered by. |
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Hu
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| Posted: Sun Jun 13, 2021 4:15 pm Post subject: |
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| When you log in, PAM is triggered. If so configured, PAM will load the pam_elogind.so module (or equivalent for systemd users). That PAM module will notify the running logind of your existence, and logind will do various privileged things on your behalf. According to one of the posts here (which I am taking on faith and not checking), one of those privileged things is creating the /run/user directory for you. |
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GDH-gentoo
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| Posted: Sun Jun 13, 2021 7:43 pm Post subject: |
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| javeree wrote: | | I don't quite understand the role of logind, neither in what exactly it does nor whwhat it gets triggered by. |
What Hu said, but here's some more detail. For example, for a text UI login on some tty:
1) User logs in, program involved in that login (/bin/login) links to PAM libraries.
| Code: | $ ldd /bin/login | grep pam
libpam.so.0 => /lib64/libpam.so.0 (0x00007fd7cab1c000)
libpam_misc.so.0 => /lib64/libpam_misc.so.0 (0x00007fd7cab17000) |
2) Code in PAM libraries does what configuration files tell it to. Configuration files tell it to load module pam_elogind.so.
/etc/pam.d/login
| Code: | | session include system-local-login |
/etc/pam.d/system-local-login
| Code: | | session include system-login |
/etc/pam.d/system-login
| Code: | | -session optional pam_elogind.so |
3) Code in PAM libraries calls function pam_sm_open_session() of pam_elogind.so:
| Code: | $ nm -D --defined-only /lib64/security/pam_elogind.so
000000000000cf80 T pam_sm_close_session
000000000000b6c0 T pam_sm_open_session |
4) Code in pam_elogind.so makes login connect to system-wide message bus and request elogind to create a session for the logged-in user:
Syslog:
| Code: | authpriv.info: Jun 13 15:32:55 login[519]: pam_unix(login:session): session opened for user <my user> (uid=1000) by LOGIN(uid=0)
auth.info: Jun 13 15:32:55 elogind-daemon[462]: New session c3 of user <my user>. |
dbus-monitor:
| Code: | method call time=1623609175.560833 sender=:1.10 -> destination=org.freedesktop.login1 serial=2 path=/org/freedesktop/login1; interface=org.freedesktop.login1.Manager; member=CreateSession
uint32 1000
uint32 0
string "login"
string "tty"
string "user"
string ""
string ""
uint32 0
string "tty1"
string ""
boolean false
string ""
string ""
array [
]
signal time=1623609175.562498 sender=:1.1 -> destination=(null destination) serial=44 path=/org/freedesktop/login1; interface=org.freedesktop.login1.Manager; member=SessionNew
string "c3"
object path "/org/freedesktop/login1/session/c3" |
5) As part of session creation, elogind creates the subdirectory of /run/user and mounts a tmpfs on it.
elogind-246.9.2/src/login/logind-user.c
| Code: | int user_new(User **ret,
Manager *m,
UserRecord *ur) {
// ...
if (asprintf(&u->runtime_path, "/run/user/" UID_FMT, ur->uid) < 0)
return -ENOMEM;
// ...
} |
elogind-246.9.2/src/login/user-runtime-dir.c
| Code: | static int do_mount(const char *runtime_path, size_t runtime_dir_size, size_t runtime_dir_inodes, uid_t uid, gid_t gid) {
// ...
return user_mkdir_runtime_path(runtime_path, uid, gid, runtime_dir_size, runtime_dir_inodes);
}
// ...
int user_runtime_dir(const char *verb, User *u) {
int r = 0;
// ...
if (streq(verb, "start"))
r = do_mount(u->runtime_path, u->manager->runtime_dir_size, u->manager->runtime_dir_inodes,
u->user_record->uid, u->user_record->gid);
// ...
} |
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javeree
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Joined: 29 Jan 2006
Posts: 461
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| Posted: Sun Jun 13, 2021 10:27 pm Post subject: |
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@GDH-gentoo
Thanks for that great rundown of what happens. this makes so much sense !
I wish many more topics were explained in this kind of fashion.
Kudos |
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Goverp
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Joined: 07 Mar 2007
Posts: 2276
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| Posted: Mon Jun 14, 2021 8:30 am Post subject: |
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FWIW, here's a script I use for creating tempfiles, using /run/user/... or /tmp or whatever, as available:
| Code: | ### Print a temp filename, using $XDG_RUNTIME_DIR if poss, /run if root, else /tmp
Tempfile()
{ local id me dir
id="$(id -n -u)"
me="${0##*/}"
if [ "$id" = "root" ]
then
dir="${XDG_RUNTIME_DIR:-/run}"
[ -d "$dir" ] || dir=""
mktemp -p "$dir" "tmp.$me.XXXXXXXXXX"
else mktemp -p "${XDG_RUNTIME_DIR}" "tmp.$id.$me.XXXXXXXXXX"
fi
}
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Use it thus:
| Code: | tmp=$(Tempfile)
echo "First line" > $tmp
echo "Second line >> $tmp
rm $tmp |
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GDH-gentoo
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| Posted: Mon Jun 14, 2021 4:19 pm Post subject: |
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| Zucca wrote: | | Hm... The program I have problems with is dte. It tries to create lock file under /run/user/$UID |
Looking at the code, it uses:
- The value of XDG_RUNTIME_DIR if the variable is set, otherwise
- The value of DTE_HOME if the variable is set, otherwise
- $HOME/.dte (and HOME better be set).
Is any of those set in the environment? |
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Zucca
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Joined: 14 Jun 2007
Posts: 4197
Location: Rasi, Finland
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| Posted: Mon Jun 14, 2021 4:51 pm Post subject: |
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| GDH-gentoo wrote: | | Is any of those set in the environment? |
| Code: | $ env | egrep 'RUNTIME|HOME'
HOME=/home/zucca
XDG_RUNTIME_DIR=/run/user/999 |
Hmmm...... so something bit deeper is acting flaky.
This is on a "remote" machine aka. home server via ssh/mosh.
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GDH-gentoo
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| Posted: Mon Jun 14, 2021 9:23 pm Post subject: |
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| And does that home server have elogind installed? If yes, that's where I'd start troubleshooting. |
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Zucca
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| Posted: Tue Jun 15, 2021 6:32 am Post subject: |
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Yeah. An elogind system.
I'll dig deeper after I get back from work.
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| My gentoo installs: | init=/sbin/openrc-init
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Zucca
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| Posted: Wed Jun 16, 2021 8:25 am Post subject: |
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I grepped the logs for logind (in case elogind uses "logind" on logs) and error, warn etc... None.
I guess I'd need to log out from every remote session and try again.
... or create a temp user to debug this.
I'll get back when I have found something or given up if I haven't found anything.
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| My gentoo installs: | init=/sbin/openrc-init
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Zucca
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Location: Rasi, Finland
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| Posted: Thu Mar 10, 2022 9:02 am Post subject: |
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This came back to bite me. This time on my laptop and is affecting user root.
I could make a workaround in /etc/profile.d, which would check if XDG_RUNTIME_DIR does not exist, then unset XDG_RUNTIME_DIR.
Clearly elogind creates the directory because it sets the variable. But at some point the directory gets deleted. The only point when it should be deleted is when the last logout of the user happens. So maybe elogind falsely detects some logout as the last?
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| My gentoo installs: | init=/sbin/openrc-init
-systemd -logind -elogind seatd |
| Quote: | | I am NaN! I am a man! |
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Zucca
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Joined: 14 Jun 2007
Posts: 4197
Location: Rasi, Finland
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| Posted: Thu Mar 10, 2022 10:01 am Post subject: hack |
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Ok. Here goes. Seems to be doing the thing. Might also break something. :D | Code: | # cat /etc/profile.d/zz_xdg_fixes.sh
#!/bin/sh
if [ "$XDG_RUNTIME_DIR" ] && [ ! -d "$XDG_RUNTIME_DIR" ]
then
if tty -s
then
# Current terminal is connected to standard input.
# We can inform the user about what we're doing.
[ "$RC_GOT_FUNCTIONS" != "yes" ] && source /lib/gentoo/functions.sh
ewarn "XDG_RUNTIME_DIR (${XDG_RUNTIME_DIR}) doesn't exist."
einfo "Unsetting XDG_RUNTIME_DIR"
fi
unset XDG_RUNTIME_DIR
fi |
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-systemd -logind -elogind seatd |
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Anon-E-moose
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Location: Dallas area
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| Posted: Thu Mar 10, 2022 11:10 am Post subject: |
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Wouldn't it be better in your .bash_profile instead of globally?
I use a script to start wayland and at the start I do a simple check and create the dir if needed. This is with openrc, not *logind
It's not the *logind that does the setting it's pam, if I remember correctly.
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Zucca
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Location: Rasi, Finland
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| Posted: Thu Mar 10, 2022 6:17 pm Post subject: |
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| Anon-E-moose wrote: | | Wouldn't it be better in your .bash_profile instead of globally? |
XDG_RUNTIME_DIR being set, but the directory missing will cause harm no matter which user encounters it. And I've now witnessed this bug (if you can call it such) with UID 1000+n and 0.
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| My gentoo installs: | init=/sbin/openrc-init
-systemd -logind -elogind seatd |
| Quote: | | I am NaN! I am a man! |
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Anon-E-moose
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Joined: 23 May 2008
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Location: Dallas area
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| Posted: Thu Mar 10, 2022 6:41 pm Post subject: |
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Is pam installed, because the XDG_RUNTIME_DIR should be set and created by pam_elogind, if I'm not mistaken.
If you're trying to set it in more than one place, then you might have a problem like you're encountering.
How do you start wayland, script, DM, *-greetd?
What are your useflags for pambase, if installed.
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Zucca
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Joined: 14 Jun 2007
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Location: Rasi, Finland
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| Posted: Thu Mar 10, 2022 8:18 pm Post subject: |
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I'm not setting XDG_RUNTIME_DIR in anywhere. The script above is only there for unsetting it is the directory does not exist.
The directories are normally there. For some reason root got its runtime dir deleted.
I'm currently using elogind and greetd+agreety on tty1 and agetty on other vts. I'm planning to write an init script for greetd+agreety for other vts too (display-manager init script doesn't do it).
| pambase USE flags: | -caps
-debug
+elogind
+gnome-keyring
-homed
-minimal
-mktemp
+nullok
-pam_krb5
-pam_ssh
+passwdqc
-pwhistory
-pwquality
-securetty
+sha512
-systemd |
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Anon-E-moose
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Joined: 23 May 2008
Posts: 6335
Location: Dallas area
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| Posted: Thu Mar 10, 2022 8:34 pm Post subject: |
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| Zucca wrote: | I'm not setting XDG_RUNTIME_DIR in anywhere. The script above is only there for unsetting it is the directory does not exist.
The directories are normally there. For some reason root got its runtime dir deleted.
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Sounds like whatever starts the process thinks that root logged out and thus cleaned up,
probably something similar for your user, not sure what elogind/pam decides what a "session" truly is.
In my script that I use to start wayland, I had to add env to pass variables, they were being dropped otherwise
| Code: | | /usr/bin/env dbus-run-session -- /usr/bin/... |
just not sure if that would help your case though.
Edit to add: post your config.toml file
ETA2: https://wiki.archlinux.org/title/Greetd might have more hints
or this https://man.sr.ht/~kennylevinsen/greetd/
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Zucca
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Joined: 14 Jun 2007
Posts: 4197
Location: Rasi, Finland
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| Posted: Sat Mar 12, 2022 11:01 am Post subject: |
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The problem here isn't relataed to greetd (most propably), since this also happened on my server earlier, which was accessed via ssh and locally only used agetty.
Also in this case root was logged in via tty2 using agetty. Then a tmux session was started and via normal user under wayfire I had su'd into the same tmux session. At some point root lost its runtime dir.
My server isn't online and even running atm. I'll try to get things going again during our spring cleanup.
Everything points into direction of elogind and pam.
| /etc/greetd/config.toml: | [terminal]
vt = 1
[default_session]
command = "/etc/greetd/greet_wrapper.sh agreety"
user = "greetd" |
... the script there basically displays a banner before execing agreety. If something other than agreety is requested, then skip displaying the banner and exec the greeter right away. But as I said before I don't have greetd in use on my server. However I can conduct tests avoiding tty1 where greetd is, but usinf other ttys where agetty runs. This way I can completely rule out greetd.
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| My gentoo installs: | init=/sbin/openrc-init
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| Quote: | | I am NaN! I am a man! |
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Zucca
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Joined: 14 Jun 2007
Posts: 4197
Location: Rasi, Finland
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| Posted: Sun Mar 13, 2022 4:50 pm Post subject: |
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I managed to reproduce the bug.
- login as root on (I did on tty2):
- start tmux session
- see /run/user/0 being present
- detach from tmux
- logout
- log in as other user:
- see /run/user/0 gone
- run su -lc 'tmux attach' and /run/user/0 still doesn't exist
I'd guess this happens also with other users than root too.
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