Date: Mon, 20 Nov 2017 14:08:12 -0600 From: Karl Denninger <karl@denninger.net> To: freebsd-fs@freebsd.org Subject: Re: MSDOS Filesystem question related to "read-only" files Message-ID: <0e31a0cf-8a97-1d63-8ebb-9c61d22539cb@denninger.net> In-Reply-To: <e6a682a1-322e-a677-3d5e-0a7a503ebd40@denninger.net> References: <f4ccb904-63fd-4641-89c8-09357fbb5a1c@denninger.net> <CAG6CVpUZumZaU9xVcri1Ry8=C6j6JrjX5F6qd3oKatYZXFu6Kg@mail.gmail.com> <e6a682a1-322e-a677-3d5e-0a7a503ebd40@denninger.net>
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This is a cryptographically signed message in MIME format. --------------ms000106040502070703060000 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Oh, my apologies -- I didn't include the version: FreeBSD 11.0-STABLE #0 r313159M: Fri Feb=C2=A0 3 09:58:35 CST 2017 On an RPI2, but I doubt that matters. On 11/20/2017 14:02, Karl Denninger wrote: > root@Test-MCP:/home/karl/HD-MCP # cd /mnt > root@Test-MCP:/mnt # mount > /dev/ufs/rootfs on / (ufs, local, noatime, soft-updates, nfsv4acls) > devfs on /dev (devfs, local) > tmpfs on /tmp (tmpfs, local) > /dev/da0s1 on /mnt (msdosfs, local) > root@Test-MCP:/mnt # ls -al > total 408 > drwxr-xr-x=C2=A0=C2=A0 1 hdmcp=C2=A0 wheel=C2=A0=C2=A0=C2=A0 4096 Jan=C2= =A0 1=C2=A0 1980 . > drwxr-xr-x=C2=A0 20 root=C2=A0=C2=A0 wheel=C2=A0=C2=A0=C2=A0=C2=A0 512 = Nov 20 16:04 .. > drwxr-xr-x=C2=A0=C2=A0 1 hdmcp=C2=A0 wheel=C2=A0=C2=A0=C2=A0 4096 Nov 1= 9 11:20 System Volume Information > -rwxr-xr-x=C2=A0=C2=A0 1 hdmcp=C2=A0 wheel=C2=A0 127979 Nov 19 22:54 > cam2-2017-11-19-22-54-47.jpg > -rwxr-xr-x=C2=A0=C2=A0 1 hdmcp=C2=A0 wheel=C2=A0 271295 Nov 19 22:57 > cam2-2017-11-19-22-57-20.jpg > root@Test-MCP:/mnt # chmod u-w * > root@Test-MCP:/mnt # ls -al > total 408 > drwxr-xr-x=C2=A0=C2=A0 1 hdmcp=C2=A0 wheel=C2=A0=C2=A0=C2=A0 4096 Jan=C2= =A0 1=C2=A0 1980 . > drwxr-xr-x=C2=A0 20 root=C2=A0=C2=A0 wheel=C2=A0=C2=A0=C2=A0=C2=A0 512 = Nov 20 16:04 .. > drwxr-xr-x=C2=A0=C2=A0 1 hdmcp=C2=A0 wheel=C2=A0=C2=A0=C2=A0 4096 Nov 1= 9 11:20 System Volume Information > -rwxr-xr-x=C2=A0=C2=A0 1 hdmcp=C2=A0 wheel=C2=A0 127979 Nov 19 22:54 > cam2-2017-11-19-22-54-47.jpg > -rwxr-xr-x=C2=A0=C2=A0 1 hdmcp=C2=A0 wheel=C2=A0 271295 Nov 19 22:57 > cam2-2017-11-19-22-57-20.jpg > root@Test-MCP:/mnt # > > Nope.=C2=A0 The "w" is still there. > > No error returned from the "chmod" command (or if I call it from a C > program) but the file mode is NOT changed whether I'm doing it as the > superuser or as the owner of the file (and directory) > > On 11/20/2017 12:30, Conrad Meyer wrote: >> Hi Karl, >> >> In fact, msdosfs in FreeBSD should set the FAT READONLY attribute >> under two conditions: >> >> 1. The owner chmod's the file non-writeable (chmod u-w) (what you've >> described, I think). Or, >> 2. The super user or otherwise privileged user sets the "readonly" >> flag on the file via chflags(1). >> >> How have you determined that chmod u-w does nothing? What version of >> FreeBSD are you using? >> >> Best, >> Conrad >> >> >> On Mon, Nov 20, 2017 at 7:36 AM, Karl Denninger <karl@denninger.net> w= rote: >>> I'm running into an interesting issue here and wondering if there's a= >>> way to do this under FreeBSD. >>> >>> MSDOS filesystems have a "primitive" permission capability; >>> specifically, they can have a "Read-only" attribute on a file. It lo= oks >>> like OpenBSD supports this from reading their man pages. >>> >>> FreeBSD doesn't appear to. When you mount a msdos filesystem (e.g. a= >>> USB stick) whoever owns the parent directory where you mount it gives= >>> you the permissions and "ownership" of files on said filesystem. All= >>> good so far. But attempting to chmod a file to remove write permissi= on >>> "succeeds" (returns success) but does nothing. >>> >>> Is this capability simply not present on FreeBSD? I'm interested in >>> using it as a means of "flagging" files on a USB stick in an applicat= ion >>> that I do not want to remove if the stick fills (basically, to "prote= ct" >>> them from being aged off) and it appears there's no way to do it, oth= er >>> than to use something unique in the filename that I would then have t= o >>> pay attention to. >>> >>> -- >>> Karl Denninger >>> karl@denninger.net <mailto:karl@denninger.net> >>> /The Market Ticker/ >>> /[S/MIME encrypted email preferred]/ --=20 Karl Denninger karl@denninger.net <mailto:karl@denninger.net> /The Market Ticker/ /[S/MIME encrypted email preferred]/ --------------ms000106040502070703060000 Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="smime.p7s" Content-Description: S/MIME Cryptographic Signature MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgMFADCABgkqhkiG9w0BBwEAAKCC 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