Which commands (in /bin & /usr/bin) must have set user ID (for root)

[Jim Webb]

This is not the beginning of a shouting match...

> What surprised me about the list Jim replied with was that most of the
> commands
> were -rws......!  Why should a setuid command *ever* be writeable? - it's just
> *inviting* attempts to find a bug and convince the command to write
> over itself.

First off, root can overwrite any file regardless of perms, yes/no?  Second,
ever see "error:  text busy" ?  You cannot remove or write over a file that
is running somewhere on the system (or, to be picky, has the sticky bit set
and has been run)

> Are there any commands that actually depend on this?

Self modifying code, perhaps :-)

> >-rwsr-xr-x   1 root     sys        47197 Oct 20  1985 at
> >-rwsr-xr-x   1 root     sys        25093 Nov  5  1983 crontab
> >at needs to talk to cron in a very specific manner.

> I would expect you could write a good cron without setuid,
> since /etc/cron runs
> as root?  Likewise "at", since it's the other side of cron?

at and crontab need to yell down /usr/lib/cron/FIFO to talk with cron.
I suppose you could make these commands setgid to some unique group and
make this pipe writable only by that group.

> What irks me more, though, is that the "lp" commands all run setuid-lp
> setgid-bin; this means that in a directory which lp can't access ( e.g. 700),
> 	lp foo
> fails, though
> 	lp <foo

then make lp suid root :-)
-- 
Jim Webb             "Out of phase--get help"          ...!ihnp4!hropus!jrw
		"Use the Force, Read the Source"