Hello!
After a Fedora 23 installation, users can't log in with sddm. A "login
failed" message is displayed by sddm, sometimes preceded by a short switch to the tty
and back. Users can log into a text console just fine. Also starting a Plasma desktop
using startx works perfectly fine.
Because sddm's logs report helper failures with codes 2 and 15, I tried this:
# cp -a /usr/libexec/sddm-helper /usr/libexec/sddm-helper-binary
# cat > /usr/libexec/sddm-helper <<-WRAPPER
#!/bin/bash
strace -f /usr/libexec/sddm-helper-binary "$@" 2>/tmp/sddm
WRAPPER
Here's the entire strace output obtained from a login attempt using the wrapper above:
https://andrej.podzimek.org/dell-strace-0.txt The strace dump shows (among other glitches)
something like a file descriptor leak. But the most important thing seems to be the
following:
[pid 1818] execve("/usr/sbin/unix_chkpwd", ["/usr/sbin/unix_chkpwd",
"andrej", "nullok"], [/* 0 vars */]) = -1 EPERM (Operation not
permitted)
[pid 1820] execve("/usr/sbin/unix_chkpwd", ["/usr/sbin/unix_chkpwd",
"andrej", "nullok"], [/* 0 vars */]) = -1 EPERM (Operation not
permitted)
I tried to make /etc/shadow readable, but that didn't help. Also tried to do
setenforce 0 and that didn't help either. :( Last but not least, rebooting with
SELinux in permissive mode does away with the EPERM error, but sddm logins hang forever,
with no chance to retry.
I looked at recent sddm bugs such as this one:
https://bugzilla.redhat.com/show_bug.cgi?id=1265813 But I don't think other sddm
issues could be directly related, because the failure pattern is different, i.e., I
can't see any segfaults here and my user IDs are in the correct range (uid 1001 in the
attached log). :(
What's wrong here? Why does sddm fail on Fedora 23? The hardware, just if it happens
to matter:
DMI: Dell Inc. Inspiron 7548/0AM6R0, BIOS A00 11/19/2014
Cheers,
Andrej