Martin McCormick <martin <at> dc.cis.okstate.edu> writes: > > The executable in question is a C program whos file > permissions are 4755 and the file belongs to root so all files > it opens are also owned by root and that works properly, but > what I need is for this application to first open a few files owned by > the caller and then later, upgrade back to root and write to > files the caller can not write to. I was hoping to avoid using > chown and chgrp and simply let the privilege level of the > application dictate ownership of any file it opens. > > When the application first runs, it gets the UID and GID > of the user and uses > > setuid(heruid); and setgid(hergid); to temporarily downgrade and > those files are owned by the right user but setuid(0); doesn't > appear to upgrade back to root. > > Is there any other strategy that gets one back to root > short of using chown and then a system call and never > downgrading privilege? > > Thank you.
Unix processes have an effective (EUID, EGID), a real (UID, GID) and a saved (SUID, SGID) ID. Get familiar with this document: http://www.cs.berkeley.edu/~daw/papers/setuid-usenix02.pdf Then verify its validity on your target and current OS. jb _______________________________________________ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "freebsd-questions-unsubscr...@freebsd.org"
