Red Hat Bugzilla – Bug 2394
permissions for /tmp/screens
Last modified: 2008-05-01 11:37:50 EDT
When I run screen as root, I get this message:
Directory '/tmp/screens' must have mode 755.
OK, chmod 755 /tmp/screens. Later I try to run screen as
regular user, and I get differnent messgae:
Directory '/tmp/screens' must have mode 777.
I can chmod 777 /tmp/screens, but hey, then I won't be able
to run screen as root...
fixed in screen-3.7.6-7, available in rawhide later this week...
screen 3.7.6-9 still not 100% ok.
If /tmp/screens does not exist and root runs screen,
then /tmp/screens is created with mode 755 !
After exiting screen and rerunning it , it complains that it
should be 777. When run by other users , then it complains too.
It it doesn't exists, when non-root runs screen , then it is created
correctly with 777.
The correct solution, now that screen doesn't run SUID root (hurrah!),
is to run screen in the mode where it stores its files in a per-user
personal .screen directory.
Much more secure than some /tmp frig.
As it stands, the first user to run screen gets ownership of
/tmp/screens, and hence can do a trivial DoS