Date: Sun, 6 Jun 2004 14:47:34 +0200 From: Stefan =?iso-8859-1?Q?E=DFer?= <se@FreeBSD.org> To: hackers@freebsd.org Subject: Semantics of "seteuid(uid)" vs. "setreuid(-1,uid)" Message-ID: <20040606124734.GA2687@StefanEsser.FreeBSD.org>
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Any reason, that there is a difference in semantics between: seteuid(id) vs. setreuid(-1, id) ??? The tests performed on the arguments are different (assuming a fixed arg of -1 for ruid) in that seteuid does not support the case of (euid == cr_uid): seteuid(euid): euid != oldcred->cr_ruid && euid != oldcred->cr_svuid setreuid(-1, euid): euid != oldcred->cr_uid && euid != oldcred->cr_ruid && euid != oldcred->cr_svuid So seteuid() may fail in cases where setreuid() with a first argument of -1 succeeds. The test obviously corresponds to POSIX appendix B.4.2.2 as mentioned in the comment in setuid(). Is the difference between seteuid() and setreuid() deliberate ? I'm asking because I have received a bug report for a port, and it appears that seteuid() on other systems is indeed equivalent to our setreuid(-1,). Regards, STefan
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