Date: Thu, 19 Aug 2010 12:40:02 GMT From: walter@pelissero.de (Walter C. Pelissero) To: freebsd-geom@FreeBSD.org Subject: Re: kern/149762: volume labels with rogue characters Message-ID: <201008191240.o7JCe2kP005865@freefall.freebsd.org>
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The following reply was made to PR kern/149762; it has been noted by GNATS.
From: walter@pelissero.de (Walter C. Pelissero)
To: jhell <jhell@DataIX.net>
Cc: bug-followup@FreeBSD.org, freebsd-bugs@FreeBSD.ORG
Subject: Re: kern/149762: volume labels with rogue characters
Date: Thu, 19 Aug 2010 14:26:26 +0200
jhell writes:
> This is a hack, something that you would commonly find in Linux
> code and is neither a proper or viable workaround for the naming of
> labels.
That's exactly what I keep repeating my friends who run Linux and brag
about features they had first or better implemented. Just a bunch of
dirty hacks any kid would have whipped up in an afternoon if he just
had the fancy. Just hacks.
Unfortunately they answer using terms like: self-indulgent inertia,
inconclusive arrogance, bureaucratic attitude, self-important sloth,
pompous underachiever. Bloody Linux kids, aren't they?
This might be an hack, but in 8 years since this issue has been first
raised nobody has came up with it, so I thought I might as well do
it.
> Instead, using glabel(8) the admin/user can create a local label to
> FreeBSD that does not change the original nor does it carry over to any
> other OS that does not understand geom_label's.
>
> >From the manual page:
>
> label Set up a label name for the given provider. This is the
> ``automatic'' method, where metadata is stored in a provider's
> last sector. The kernel module geom_label.ko will be loaded if
> it is not loaded already.
Can anyone explain me how metadata stored on media cannot interfere
with other OSs?
Below I include a revised patch that turns kern.geom.label.sanitation
into a bitmask, thus allowing to enable selectively the replacements,
as I have been struck by the fact that slashes in labels might be
desirable, as they create a path (although the parent directory is
left behind after the device disappearance).
Now kern.geom.label.sanitation can be set to zero (default) obtaining
the usual behaviour without "hack". So that when I meet up with some
Vogon friends, who coincidentally all run exclusively FreeBSD or VMS,
I can revert the sysctl and show them their volume labels coded in
UTF-16. Well, yes, "show". Typing those labels at the shell prompt
is another story altogether, but at least they won't scoff at me as if
I was a Linux hacker!
Index: g_label.c
===================================================================
RCS file: /repos/src/sys/geom/label/g_label.c,v
retrieving revision 1.24.2.4
diff -c -r1.24.2.4 g_label.c
*** g_label.c 22 Jun 2010 08:17:20 -0000 1.24.2.4
--- g_label.c 19 Aug 2010 11:27:13 -0000
***************
*** 136,141 ****
--- 136,161 ----
return (1);
}
+ static int sanitation_mask = 0;
+ SYSCTL_INT(_kern_geom_label, OID_AUTO, sanitation, CTLFLAG_RW,
+ &sanitation_mask, 0,
+ "Correction applied to labels. A bitmask of: 0 = none, 1 = replace '/'s, 2 = replace whitespace and ctrls, 4 = replace anything beyond '~'");
+
+ static void
+ sanitise_name (char *name)
+ {
+ unsigned char *p;
+
+ for (p = name; *p; ++p) {
+ if ((sanitation_mask & 1) && *p == '/')
+ *p = '#';
+ else if ((sanitation_mask & 2) && *p <= ' ')
+ *p = '_';
+ else if ((sanitation_mask & 4) && *p > '~')
+ *p = '?';
+ }
+ }
+
static struct g_geom *
g_label_create(struct gctl_req *req, struct g_class *mp, struct g_provider *pp,
const char *label, const char *dir, off_t mediasize)
***************
*** 156,161 ****
--- 176,182 ----
gp = NULL;
cp = NULL;
snprintf(name, sizeof(name), "%s/%s", dir, label);
+ sanitise_name(name + strlen(dir) + 1);
LIST_FOREACH(gp, &mp->geom, geom) {
pp2 = LIST_FIRST(&gp->provider);
if (pp2 == NULL)
--
walter pelissero
http://www.pelissero.de
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