Execute permissions on /usr/etc/halt

[Barry Margolin]

In article <356 at brchh104.bnr.ca> patrick at casbs.stanford.edu (Patrick Goebel) writes:
>On our 4/330 running SunOS 4.0.3 I find:
>
>% ls -lFg /usr/etc/halt
>-rwxr-xr-x  1 root     staff       81920 Apr 24  1989 halt*
>
>Don't these permissions imply that any mortal user could halt the system?!

No.  The halt program has to perform a system call to actually reboot the
system, and this system call is restricted to the superuser (otherwise any
user could write their own halt program).

It would be a problem if /usr/etc/halt were *setuid* to root, e.g. if the
permission were -rwsr-xr-x.

Barry Margolin, Thinking Machines Corp.

barmar at think.com
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