Re: strace security <feature>

Alan Cox (alan@lxorguk.ukuu.org.uk)
Thu, 30 Dec 1999 14:50:13 +0000 (GMT)


> Further, the suid bit only sets the EUID during exec, not UID and GID.

Correct

> Previously a privileged program would have to specifically set its UID
> and GID to obtain privilege. In other words, EUID was only checked on

Wrong. It checks euid always (e= effective)

> setuid()/setgid() calls. The call would fail if the EUID was not 0.

Wrong

> All other system calls would check UID/GID only and fail without
> privilege.

Wrong (they check euid - actually in Linux capabilities but thats the same
effect)

> Now I see the rules have been changed so that if the EUID *or* the UID
> are 0, the system calls are allowed to function as though the UID was 0.
> If this corresponds to later POSIX rules, the committee should consider
> the implications without regard to maintaining reverse compatibility.

Wrong (You also want SuS not Posix for this)

> 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.

Only if you are also running with Solar_Diz TPE patches.

Alan

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