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Date: Sat, 13 Mar 2010 10:35:52 +0200
From: Jaakko Heinonen <jh@FreeBSD.org>
To: freebsd-geom@FreeBSD.org
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Cc: pjd@FreeBSD.org, phk@FreeBSD.org
Subject: Escape unsafe characters for kern.geom.confxml XML dump
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Hi,

I intend to commit following patch unless there are objections. I have
seen the problem commonly reported by FreeBSD users.

---

Escape characters unsafe for XML output in GEOM class, instance and provider
names.

- Characters in range 0x01-0x1f except '\t', '\n', and '\r' are replaced
  with '?'. Those characters are disallowed in XML.
- '&', '<', '>', '\'', '"' and characters in range 0x7f-0xff are replaced
  with XML numeric character reference.

If the kern.geom.confxml sysctl provides invalid XML, libgeom
geom_xml2tree() fails and utilities using it do not work. Unsafe
characters are common in msdosfs and cd9660 labels.

PR:		kern/104389
Submitter by:	Doug Steinwand (original version)

%%%
Index: sys/geom/geom_dump.c
===================================================================
--- sys/geom/geom_dump.c	(revision 205081)
+++ sys/geom/geom_dump.c	(working copy)
@@ -154,6 +154,28 @@ g_conftxt(void *p, int flag)
 
 
 static void
+g_conf_print_escaped(struct sbuf *sb, const char *fmt, const char *str)
+{
+	struct sbuf *s;
+	const u_char *c;
+
+	s = sbuf_new_auto();
+
+	for (c = str; *c != '\0'; c++) {
+		if (*c == '&' || *c == '<' || *c == '>' ||
+		    *c == '\'' || *c == '"' || *c > 0x7e)
+			sbuf_printf(s, "&#x%X;", *c);
+		else if (*c == '\t' || *c == '\n' || *c == '\r' || *c > 0x1f)
+			sbuf_putc(s, *c);
+		else
+			sbuf_putc(s, '?');
+	}
+	sbuf_finish(s);
+	sbuf_printf(sb, fmt, sbuf_data(s));
+	sbuf_delete(s);
+}
+
+static void
 g_conf_consumer(struct sbuf *sb, struct g_consumer *cp)
 {
 
@@ -181,7 +203,7 @@ g_conf_provider(struct sbuf *sb, struct 
 	sbuf_printf(sb, "\t  <geom ref=\"%p\"/>\n", pp->geom);
 	sbuf_printf(sb, "\t  <mode>r%dw%de%d</mode>\n",
 	    pp->acr, pp->acw, pp->ace);
-	sbuf_printf(sb, "\t  <name>%s</name>\n", pp->name);
+	g_conf_print_escaped(sb, "\t  <name>%s</name>\n", pp->name);
 	sbuf_printf(sb, "\t  <mediasize>%jd</mediasize>\n",
 	    (intmax_t)pp->mediasize);
 	sbuf_printf(sb, "\t  <sectorsize>%u</sectorsize>\n", pp->sectorsize);
@@ -208,7 +230,7 @@ g_conf_geom(struct sbuf *sb, struct g_ge
 
 	sbuf_printf(sb, "    <geom id=\"%p\">\n", gp);
 	sbuf_printf(sb, "      <class ref=\"%p\"/>\n", gp->class);
-	sbuf_printf(sb, "      <name>%s</name>\n", gp->name);
+	g_conf_print_escaped(sb, "      <name>%s</name>\n", gp->name);
 	sbuf_printf(sb, "      <rank>%d</rank>\n", gp->rank);
 	if (gp->flags & G_GEOM_WITHER)
 		sbuf_printf(sb, "      <wither/>\n");
@@ -237,7 +259,7 @@ g_conf_class(struct sbuf *sb, struct g_c
 	struct g_geom *gp2;
 
 	sbuf_printf(sb, "  <class id=\"%p\">\n", mp);
-	sbuf_printf(sb, "    <name>%s</name>\n", mp->name);
+	g_conf_print_escaped(sb, "    <name>%s</name>\n", mp->name);
 	LIST_FOREACH(gp2, &mp->geom, geom) {
 		if (gp != NULL && gp != gp2)
 			continue;
%%%

-- 
Jaakko