/var/run/utmp permissions differ from those suggested in man 5 utmp

pwc101 · 10-09-2008, 04:53 AM

Slackware 12.1 fully up-to-date.

Code:

root@slack:~# ls -l /var/run/utmp
-rw-rw-r-- 1 root utmp 3456 2008-10-09 10:28  /var/run/utmp
root@slack:~#

Quote:

Originally Posted by man 5 utmp

Warning: utmp must not be writable, because many system programs (fool-
ishly) depend on its integrity. You risk faked system logfiles and
modifications of system files if you leave utmp writable to any user.

I checked on a clean install in a virtual machine, and the permissions are the same. Is this a problem?

keefaz · 10-09-2008, 05:26 AM

Quote:

if you leave utmp writable to any user.

Code:

root@slack:~# ls -l /var/run/utmp
-rw-rw-r-- 1 root utmp 3456 2008-10-09 10:28  /var/run/utmp
root@slack:~#

So where is the problem? utmp is not writable as shown from ls output

pwc101 · 10-09-2008, 05:54 AM

I misunderstood the two statements: "utmp must not be writable" and subsequently "writable by any user" as meaning utmp must not be writable to anyone, no matter whether they owned the file or were part of its group (hence any user). I was expecting to see permissions of -r--r--r-- if anything. Thanks for pointing out the real meaning (though I think the man page could be worded less ambiguously).

Panic over.

keefaz · 10-09-2008, 06:49 AM

Maybe replace "any user" with "other user" ?
English is not my first language though, so I can't tell
But if a Linux admin set any user in utmp group, he should be fired asap imo

pwc101 · 10-09-2008, 10:46 AM

Quote:

Originally Posted by keefaz

Maybe replace "any user" with "other user" ?
English is not my first language though, so I can't tell

I've sent an email to the linux man page bug reporting system with a slight clarification, although it's quite difficult to explain without ambiguity!

Quote:

Originally Posted by keefaz

But if a Linux admin set any user in utmp group, he should be fired asap imo

True!

saurabh nigam · 02-14-2011, 10:46 PM

Hi all , did any of you figured the solution?
In my case too it says

Code:

touch /var/run/utmp :No such file or directory
chown /var/run/utmp :No such file or directory
chmod /var/run/utmp :No such file or directory
touch /var/lock/subsys/serial :No such file or directory

then it hangs on to

Code:

sysklogd

and doesn't boots further but it does boot in single user mode (& I can login as root).
Help.