setuid (was Re: Non Destructive Version of rm)

[Kartik Subbarao]

In article <1991May21.121555.5087 at convex.com> tchrist at convex.COM (Tom Christiansen) writes:
>From the keyboard of chap at art-sy.detroit.mi.us (j chapman flack):
>:The man page mentions that on "some" systems pwd(1) does not run setuid-root
>:and so can't pwd if the parent or an ancestor directory is unreadable.
>:
>:My system is one of those.  Is there something intrinsically unsafe about pwd
>:that would create holes if I made it setuid-root?
>
>I can't really think of anything, but this is scant evidence, let alone
>proof, of trustworthiness.  Most of us seem to get by find without a suid
>pwd(1).  It fails whenever a normal getwd(3) would fail, but few of us
>consider this critical.  So what?  The fewer suid programs (and the fewer
>programs root always runs) the less you have to worry about.  And I don't
>think implementing getwd(3) via a popen(3) to a suid pwd(1) is a very
>elegant solution.

I agree. What people might be grumbling about is the fact that if you cd down
into subdirectories of a directory that is mode 711, /bin/pwd, since
it only does a straight getcwd(), fails because it can't find where it is
now. But, decent shells such as zsh have pwd as a builtin, so there's no
problem. It would seem that it is the shell's responsibility to do that kind
of stuff. Also, an ofiles on your shell process should also tell you where you 
are.


			-Kartik

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