Date: Wed, 6 Oct 2010 10:09:21 -0700 From: Garrett Cooper <gcooper@FreeBSD.org> To: Alexander Best <arundel@freebsd.org> Cc: freebsd-hackers@freebsd.org Subject: Re: issue with unsetting 'arch' flag Message-ID: <AANLkTi=sA4GP=B61tbEmG6B0CYcET=dCFMJByoS_5=yi@mail.gmail.com> In-Reply-To: <20101005235054.GA45827@freebsd.org> References: <20101005235054.GA45827@freebsd.org>
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[-- Attachment #1 --]
On Tue, Oct 5, 2010 at 4:50 PM, Alexander Best <arundel@freebsd.org> wrote:
> hi there,
>
> i think the following example shows the problem better than a long explanation:
>
> `touch ftest && chflags arch ftest && chflags -vv 0 ftest`.
> ^^non-root ^^root ^^non-root
>
> chflags claims to have cleared the 'arch' flag (which should be impossible as
> non-root user), but indeed has done nothing.
>
> i've tried the same with 'sappnd' and that works as can be expected.
>
> The issue was confirmed to exist in HEAD (me), stable/8 (pgollucc1, jpaetzel)
> and stable/7 (nox).
> On stable/6 it does NOT exist (jpaetzel). chflags properly fails with EPERM.
Fails for me when I call the syscall directly, as I would expect,
and passes when I'm superuser:
$ ./test_chflags
(uid, euid) = (1000, 1000)
test_chflags: chflags: Operation not permitted
test_chflags: lchflags: Operation not permitted
$ sudo ./test_chflags
(uid, euid) = (0, 0)
According to my basic inspection in strtofflags
(.../lib/libc/gen/strtofflags.c), it works as well.
And last but not least, executing the commands directly on the CLI work:
$ tmpfile=`mktemp /tmp/chflags.XXXXXX`
$ chflags arch $tmpfile
chflags: /tmp/chflags.nQm1IL: Operation not permitted
$ rm $tmpfile
$ tmpfile=`mktemp /tmp/chflags.XXXXXX`
$ sudo chflags arch $tmpfile
$ sudo chflags noarch $tmpfile
$ rm $tmpfile
Your results may (but shouldn't) vary [unless your environment is
setup differently]...
Please note that I'm using UFS2 with SUJ... not all filesystems
support this (ext2/3/4? msdosfs? ZFS?), so I would be careful about
which filesystem you pick and whether or not there's a bug where it's
not properly identifying that the operation you're attempting to
perform is valid.
Thanks,
-Garrett
$ uname -a
FreeBSD bayonetta.local 9.0-CURRENT FreeBSD 9.0-CURRENT #9 r211309M:
Thu Aug 19 22:50:36 PDT 2010
root@bayonetta.local:/usr/obj/usr/src/sys/BAYONETTA amd64
[-- Attachment #2 --]
#include <sys/stat.h>
#include <err.h>
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
int main(int argc, char*argv[])
{
printf("(uid, euid) = (%d, %d)\n", getuid(), geteuid());
char template[] = "/tmp/chflags.XXXXXX";
char *tmpfile;
tmpfile = mktemp(template);
if (tmpfile == NULL)
err(1, "mktemp");
if (close(open(tmpfile, O_CREAT)))
err(1, "close(open(..))");
if (chflags(tmpfile, SF_ARCHIVED) != 0)
warn("chflags");
if (lchflags(tmpfile, SF_ARCHIVED) != 0)
warn("lchflags");
if (chflags(tmpfile, 0) != 0)
err(1, "chflags(0)");
else
unlink(tmpfile);
return (0);
}
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