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Bug 2394 - permissions for /tmp/screens
Summary: permissions for /tmp/screens
Alias: None
Product: Red Hat Linux
Classification: Retired
Component: screen
Version: 6.0
Hardware: i386
OS: Linux
Target Milestone: ---
Assignee: David Lawrence
QA Contact:
Depends On:
TreeView+ depends on / blocked
Reported: 1999-04-28 15:31 UTC by Leos Bitto
Modified: 2008-05-01 15:37 UTC (History)
1 user (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Last Closed: 1999-04-28 15:54:58 UTC

Attachments (Terms of Use)

Description Leos Bitto 1999-04-28 15:31:20 UTC
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...

Comment 1 Bill Nottingham 1999-04-28 15:54:59 UTC
fixed in screen-3.7.6-7, available in rawhide later this week...

Comment 2 David Balažic 1999-06-18 14:42:59 UTC
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.

Comment 3 Chris Evans 1999-06-18 16:05:59 UTC
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

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