From: daw@cs.berkeley.edu (David Wagner)
To: linux-kernel@vger.kernel.org
Subject: Re: EUID != root + EGID = root, and CAP_SETGID
Date: Sun, 13 Dec 2009 05:19:56 +0000 (UTC) [thread overview]
Message-ID: <hg1ths$g05$1@taverner.cs.berkeley.edu> (raw)
In-Reply-To: 4B222C3D.2070807@icdsoft.com
Ivan Zahariev wrote:
>Is this an intended behavior?
Yes. Setuid/setgid are a mess. For more details, you might
find the following research papers interesting:
http://www.cs.berkeley.edu/~daw/papers/setuid-usenix02.pdf
http://www.cs.berkeley.edu/~daw/papers/setuid-login08b.pdf
See, e.g., Section 5.2 of the former paper, which says:
"an effective group ID of zero does not accord any
special privileges to change groups. This is a potential
source of confusion: it is tempting to assume incorrectly
that since appropriate privileges are carried by the euid
in the setuid-like calls, they will be carried by the
egid in the setgid-like calls, but this is not how it
actually works. This misconception caused a mistake in
the manual page of setgid in Redhat Linux 7.2 (Section
6.4.1)."
prev parent reply other threads:[~2009-12-13 5:45 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-11 11:25 EUID != root + EGID = root, and CAP_SETGID Ivan Zahariev
2009-12-11 12:04 ` Andreas Schwab
2009-12-13 5:19 ` David Wagner [this message]
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