setuid issues

[Beeblebrox]

I am not able to find by searching, an accurate answer to this overall problem:

1. GDM starts but then freezes and shows no login window. Stopping gdm has no effect andthe process just re-launches on its own. Log files under /var/log/gdm show size but all are empty; when I try to open one of the files with nano, it says "New File". Only looking through messages.log was I able to find the culprit:

gdm-simple-slave: warning: unable to open session: the permission of the setuid helper is not correct

2. SUDO complains:

must be setuid root

I have found this answer for the sudo problem, but I think there's a more fundamental issue with setuid.
chmod 4555 /usr/bin/su

I have read in several places that this is a dbus issue abd I have re-installed it - no effect.
my ZFS mounts have setuid=off (incl var & tmp). I turned this on for var, tmp & root, but to no effect.

 

[mamalos]

I am not sure if I have understood correctly, but in order for /usr/bin/su to be suid (and behave like this), then the closest mount point (eg. /usr/) should be mounted with options allowing the suid bit to be set.

On your second comment you mention sudo, but write /usr/bin/su on your answer instead. Did you mean /usr/local/bin/sudo (or wherever sudo is installed on your system)?

 

[Beeblebrox]

you were right - turning on suid for /usr under zfs solved the problem. No need for suid on others (root, var, tmp)
zfs set setuid=on pool/usr
AWESOME THANKS - gdm also starts w/o problems

did not have to do anything about /usr/local/bin/sudo