[SOLVED] I am not being asked for a password upon login.

Lootwig · 2019-03-10 00:36:25

Hello ArchLinux Community,
I have been using Arch for half a year now. Recently I also installed it on my Lenovo Thinkpad.

I am using:
* GNOME
* gdm
* zsh as the standart shell (oh-my-zsh config)
* fprintd

Last day I was playing around with some GNOME-Shell extensions, when I discovered, that I can escape the GNOME-Lockscreen when just pressing random buttons (for example space just unlocks the screen).
I investigated the files in "/etc/pam.d/", because I knew I modified some of them when installing fprintd (to enable sudo with fingerprint). I tried to comment-out all references to fprintd and then reinstalling it and some other stuff.
Now I am not even asked for anything upon login. This is no GNOME problem! When I disable the gdm.service and try to log into a tty-shell, I have the same problem: no password is asked of me.
But the strange thing is: I am asked for a password when I use sudo in a terminal.
I also tried changing the password, but that won't help neither.

Maybe anyone has some idea, what could have gone wrong. I'm not entirely sure if it is a problem in "/etc/pam.d/", that was just the only place I can imagine anything being wrong.

I'm really thankful for any input or ideas, you can give me, as I'm running out of ideas and obviously don't want anybody to be able just to access my Laptop.

Thanks to anybody answering this
Lootwig

Last edited by Lootwig (2019-03-10 15:42:17)

seth · 2019-03-10 08:05:17

for name in `for name in /etc/pam.d/*; do pacman -Qoq $name 2>&1; done | sort | uniq`; do pacman -Qkk $name; done

Lootwig · 2019-03-10 10:43:59

Thanks for looking at it. The output was:

>for name in `for name in /etc/pam.d/*; do sudo pacman -Qoq $name 2&gt;&amp;1; done | sort | uniq`; do sudo pacman -Qkk $name; done           
warning: cronie: /etc/cron.hourly/0anacron (Modification time mismatch)
warning: cronie: /etc/cron.hourly/0anacron (Size mismatch)
cronie: 41 total files, 1 altered file
warning: cups: /etc/cups/classes.conf (Permissions mismatch)
warning: cups: /etc/cups/printers.conf (Permissions mismatch)
warning: cups: /etc/cups/subscriptions.conf (Permissions mismatch)
backup file: cups: /etc/cups/subscriptions.conf (Modification time mismatch)
backup file: cups: /etc/cups/subscriptions.conf (Size mismatch)
cups: 872 total files, 3 altered files
backup file: gdm: /etc/gdm/custom.conf (Modification time mismatch)
backup file: gdm: /etc/gdm/custom.conf (Size mismatch)
backup file: gdm: /etc/pam.d/gdm-fingerprint (Modification time mismatch)
backup file: gdm: /etc/pam.d/gdm-fingerprint (Size mismatch)
gdm: 499 total files, 0 altered files
gnome-screensaver: 282 total files, 0 altered files
inetutils: 56 total files, 0 altered files
openssh: 58 total files, 0 altered files
backup file: pambase: /etc/pam.d/system-local-login (Modification time mismatch)
backup file: pambase: /etc/pam.d/system-local-login (Size mismatch)
pambase: 8 total files, 0 altered files
polkit: 199 total files, 0 altered files
shadow: 558 total files, 0 altered files
backup file: sudo: /etc/sudoers (Modification time mismatch)
backup file: sudo: /etc/sudoers (Size mismatch)
backup file: sudo: /etc/pam.d/sudo (Modification time mismatch)
backup file: sudo: /etc/pam.d/sudo (Size mismatch)
sudo: 202 total files, 0 altered files
systemd: 1600 total files, 0 altered files
util-linux: 494 total files, 0 altered files

Hope that can give some insight.

seth · 2019-03-10 12:14:07

/etc/pam.d/system-local-login kinda sticks out?

Lootwig · 2019-03-10 15:37:30

Thanks a lot!

That file was broken (I must have deleted one line accidently). Now everything is working fine
It really helped me, because at this point I was quite frustrated.
Actually I learned a lot, and hopefully I can help myself better next time. (After Inspecting your short script, I now know how to look for damaged files )

Arch's community really is a great community!

I wish you a great Day!
Lootwig

PS: I will mark this thread as [solved].

Trilby · 2019-03-10 15:46:42

Wait a minute though that can't be all. I'll admit to knowing very little about pam, and what little I know disturbs me, but this so much more so than previous experience.

By the file being "broken" do you mean you specifically inserted something in the file that should allow such behavior? There is no way that a security tool's config file being broken or corrupted should result in anyone being able to log in as a user without any password. If that is indeed the case, this should be a high severity bug against pam.

seth · 2019-03-10 15:54:31

Comment the "auth include system-login" line, be scared ;-)

Trilby · 2019-03-10 15:56:08

WTF?! That can't be intentional. That's horrible.

Lootwig · 2019-03-10 16:09:45

Yes, I just deleted one line by accident. That was the content of the file:

#%PAM-1.0

account   include   system-login
password  include   system-login
session   include   system-login

I simply made a backup of the file and deleted the old file and then I reinstalled the pam package.

Lootwig · 2019-03-10 16:11:30

And BTW: I was able to login as any user, even root.

seth · 2019-03-10 16:30:52

Well, it's a pluggable authentication module thing.
I assume if you unplug all challenges, that's what you can expect to get - I'm not terribly surprised.

Securitywise it's not much different from editing /etc/shadow - you got to be root to do either and root access just means that you can fudge the system in a gazillion ways…

Arch Linux

#1 2019-03-10 00:36:25

[SOLVED] I am not being asked for a password upon login.

#2 2019-03-10 08:05:17

Re: [SOLVED] I am not being asked for a password upon login.

#3 2019-03-10 10:43:59

Re: [SOLVED] I am not being asked for a password upon login.

#4 2019-03-10 12:14:07

Re: [SOLVED] I am not being asked for a password upon login.

#5 2019-03-10 15:37:30

Re: [SOLVED] I am not being asked for a password upon login.

#6 2019-03-10 15:46:42

Re: [SOLVED] I am not being asked for a password upon login.

#7 2019-03-10 15:54:31

Re: [SOLVED] I am not being asked for a password upon login.

#8 2019-03-10 15:56:08

Re: [SOLVED] I am not being asked for a password upon login.

#9 2019-03-10 16:09:45

Re: [SOLVED] I am not being asked for a password upon login.

#10 2019-03-10 16:11:30

Re: [SOLVED] I am not being asked for a password upon login.

#11 2019-03-10 16:30:52

Re: [SOLVED] I am not being asked for a password upon login.

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