Messages in this thread | | | From | (David Wagner) | Subject | Re: EUID != root + EGID = root, and CAP_SETGID | Date | Sun, 13 Dec 2009 05:19:56 +0000 (UTC) |
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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)."
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