Re: strace security <feature>

Miquel van Smoorenburg (miquels@cistron.nl)
30 Dec 1999 14:48:59 GMT

In article <cistron.Pine.LNX.3.95.991230092414.766A-100000@chaos.analogic.com>,
Richard B. Johnson <root@chaos.analogic.com> wrote:
>Further, the suid bit only sets the EUID during exec, not UID and GID.
>Previously a privileged program would have to specifically set its UID
>and GID to obtain privilege. In other words, EUID was only checked on
>setuid()/setgid() calls. The call would fail if the EUID was not 0.

Nonsense. The kernel only uses the effective uid and gid in most cases.
Why do you think it is called "effective" ?

>Certainly `cp` never attempted to obtain root privilege so the suid-root
>bit set in its parent's file should have done nothing.

Yes, well, welcome to Unix.

>Also, I think I have read (recently) that, for a program to function
>suid-root, it must be owned by root and exist in a root-owned directory.
>This does not seem to be in current implementation, I can make a suid-root
>program, put it in a directory owned by 200.200, and it still shows
>the EUID as 0.

Yes well ofcourse. Think hardlinks. Welcome to Unix, once again ;)

Mike.

-- 
Living is a horizontal fall.

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