From 2ec75967d9ddd20378e03a5e7c46cb126972747c Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Tue, 14 Aug 2012 18:28:37 -0400
Subject: Prevent access to external files/URLs via contrib/xml2's
 xslt_process().

libxslt offers the ability to read and write both files and URLs through
stylesheet commands, thus allowing unprivileged database users to both read
and write data with the privileges of the database server.  Disable that
through proper use of libxslt's security options.

Also, remove xslt_process()'s ability to fetch documents and stylesheets
from external files/URLs.  While this was a documented "feature", it was
long regarded as a terrible idea.  The fix for CVE-2012-3489 broke that
capability, and rather than expend effort on trying to fix it, we're just
going to summarily remove it.

While the ability to write as well as read makes this security hole
considerably worse than CVE-2012-3489, the problem is mitigated by the fact
that xslt_process() is not available unless contrib/xml2 is installed,
and the longstanding warnings about security risks from that should have
discouraged prudent DBAs from installing it in security-exposed databases.

Reported and fixed by Peter Eisentraut.

Security: CVE-2012-3488
---
 contrib/xml2/expected/xml2.out   | 15 +++++++++++++++
 contrib/xml2/expected/xml2_1.out | 15 +++++++++++++++
 2 files changed, 30 insertions(+)

(limited to 'contrib/xml2/expected')

diff --git a/contrib/xml2/expected/xml2.out b/contrib/xml2/expected/xml2.out
index 3bf676fb400..eba6ae60364 100644
--- a/contrib/xml2/expected/xml2.out
+++ b/contrib/xml2/expected/xml2.out
@@ -207,3 +207,18 @@ SELECT xslt_process('<employee><name>cim</name><age>30</age><pay>400</pay></empl
  
 (1 row)
 
+-- possible security exploit
+SELECT xslt_process('<xml><foo>Hello from XML</foo></xml>',
+$$<xsl:stylesheet version="1.0"
+      xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
+      xmlns:sax="http://icl.com/saxon"
+      extension-element-prefixes="sax">
+
+  <xsl:template match="//foo">
+    <sax:output href="0wn3d.txt" method="text">
+      <xsl:value-of select="'0wn3d via xml2 extension and libxslt'"/>
+      <xsl:apply-templates/>
+    </sax:output>
+  </xsl:template>
+</xsl:stylesheet>$$);
+ERROR:  failed to apply stylesheet
diff --git a/contrib/xml2/expected/xml2_1.out b/contrib/xml2/expected/xml2_1.out
index fda626e08c7..bac90e5a2a9 100644
--- a/contrib/xml2/expected/xml2_1.out
+++ b/contrib/xml2/expected/xml2_1.out
@@ -151,3 +151,18 @@ SELECT xslt_process('<employee><name>cim</name><age>30</age><pay>400</pay></empl
   </xsl:template>
 </xsl:stylesheet>$$::text, 'n1="v1",n2="v2",n3="v3",n4="v4",n5="v5",n6="v6",n7="v7",n8="v8",n9="v9",n10="v10",n11="v11",n12="v12"'::text);
 ERROR:  xslt_process() is not available without libxslt
+-- possible security exploit
+SELECT xslt_process('<xml><foo>Hello from XML</foo></xml>',
+$$<xsl:stylesheet version="1.0"
+      xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
+      xmlns:sax="http://icl.com/saxon"
+      extension-element-prefixes="sax">
+
+  <xsl:template match="//foo">
+    <sax:output href="0wn3d.txt" method="text">
+      <xsl:value-of select="'0wn3d via xml2 extension and libxslt'"/>
+      <xsl:apply-templates/>
+    </sax:output>
+  </xsl:template>
+</xsl:stylesheet>$$);
+ERROR:  xslt_process() is not available without libxslt
-- 
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