Date: Mon, 12 Jan 2009 15:45:44 +0000 (GMT) From: Robert Watson <rwatson@FreeBSD.org> To: Tim Kientzle <kientzle@freebsd.org> Cc: freebsd-hackers@freebsd.org, pluknet <pluknet@gmail.com> Subject: Re: extattr problems? Message-ID: <alpine.BSF.2.00.0901121543520.16794@fledge.watson.org> In-Reply-To: <496ABD9A.8080006@freebsd.org> References: <49692659.2030306@freebsd.org> <a31046fc0901101836q1f43028awe4f7b0ba746248ac@mail.gmail.com> <49696C24.8010601@freebsd.org> <a31046fc0901110004m629f9aeegc4ac1cdfd1591c69@mail.gmail.com> <496AA714.1090904@freebsd.org> <496ABD9A.8080006@freebsd.org>
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On Sun, 11 Jan 2009, Tim Kientzle wrote: > I think this one is a bug. It appears that extattr_set_fd() obeys the > permissions on the file, not the permissions of the descriptor. In > particular, I see this on FreeBSD 6.3: Hmm. Not clear. EAs live in a slightly hazy world between data and meta-data. Normally you can perform operations like fchmod(2), which are strictly meta-data operations, regardless of the flags of the file descriptor they are performed on, subject to ownership/permissions. With NFSv4 ACLs, where the right to change ACLs can be delegated, this only becomes more true. I've chosen to generally treat EAs as meta-data in this regard, where the file descriptor simply names the object rather than as an access method as occurs with write(), etc. How do other systems handle this -- for example, Linux, with its notion of user vs. system namespaces? Robert N M Watson Computer Laboratory University of Cambridge > > [tim@dark /tmp]$ ./extattr_test > fd=3 > extattr_set_fd() = -1 > errno = 13 (Permission denied) > [tim@dark /tmp]$ cat extattr_test.c > #include <sys/types.h> > #include <sys/extattr.h> > #include <errno.h> > #include <fcntl.h> > #include <stdio.h> > > int > main(int argc, char **argv) > { > int n, fd; > > fd = open("/tmp/test12345", O_RDWR | O_CREAT | O_EXCL, 0000); > printf("fd=%d\n", fd); > n = extattr_set_fd(fd, EXTATTR_NAMESPACE_USER, > "testattr", "1234", 4); > printf("extattr_set_fd() = %d\n", n); > if (n != 0) > printf("errno = %d (%s)\n", > errno, strerror(errno)); > exit(0); > } > _______________________________________________ > freebsd-hackers@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-hackers > To unsubscribe, send any mail to "freebsd-hackers-unsubscribe@freebsd.org" >
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