libupnp: add upstream security fix for CVE-2016-6255

If there's no registered handler for a POST request, the default behaviour
is to write it to the filesystem. Several million deployed devices appear
to have this behaviour, making it possible to (at least) store arbitrary
data on them. Add a configure option that enables this behaviour, and change
the default to just drop POSTs that aren't directly handled.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
(cherry picked from commit 9d1dab1b80ae5b0851e29b9273e248d966ad8637)

package/libupnp/0001-Don-t-allow-unhandled-POSTs-to-write-to-the-filesyst.patch

@@ -0,0 +1,73 @@
+From c91a8a3903367e1163765b73eb4d43be7d7927fa Mon Sep 17 00:00:00 2001
+From: Matthew Garrett <mjg59@srcf.ucam.org>
+Date: Tue, 23 Feb 2016 13:53:20 -0800
+Subject: [PATCH] Don't allow unhandled POSTs to write to the filesystem by
+ default
+
+Fixes CVE-2016-6255: write files via POST
+
+If there's no registered handler for a POST request, the default behaviour
+is to write it to the filesystem. Several million deployed devices appear
+to have this behaviour, making it possible to (at least) store arbitrary
+data on them. Add a configure option that enables this behaviour, and change
+the default to just drop POSTs that aren't directly handled.
+
+Signed-off-by: Marcelo Roberto Jimenez <mroberto@users.sourceforge.net>
+Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
+---
+ configure.ac                         | 4 ++++
+ upnp/inc/upnpconfig.h.in             | 5 +++++
+ upnp/src/genlib/net/http/webserver.c | 4 ++++
+ 3 files changed, 13 insertions(+)
+
+diff --git a/configure.ac b/configure.ac
+index dd88734..ea2bc09 100644
+--- a/configure.ac
++++ b/configure.ac
+@@ -482,6 +482,10 @@ if test "x$enable_scriptsupport" = xyes ; then
+         AC_DEFINE(IXML_HAVE_SCRIPTSUPPORT, 1, [see upnpconfig.h])
+ fi
+ 
++RT_BOOL_ARG_ENABLE([postwrite], [no], [write to the filesystem on otherwise unhandled POST requests])
++if test "x$enable_postwrite" = xyes ; then
++        AC_DEFINE(UPNP_ENABLE_POST_WRITE, 1, [see upnpconfig.h])
++fi
+ 
+ RT_BOOL_ARG_ENABLE([samples], [yes], [compilation of upnp/sample/ code])
+ 
+diff --git a/upnp/inc/upnpconfig.h.in b/upnp/inc/upnpconfig.h.in
+index 46ddc6e..5df8c5a 100644
+--- a/upnp/inc/upnpconfig.h.in
++++ b/upnp/inc/upnpconfig.h.in
+@@ -135,5 +135,10 @@
+  *  (i.e. configure --enable-open_ssl) */
+ #undef UPNP_ENABLE_OPEN_SSL
+ 
++/** Defined to 1 if the library has been compiled to support filesystem writes on POST
++ *  (i.e. configure --enable-postwrite) */
++#undef UPNP_ENABLE_POST_WRITE
++
++
+ #endif /* UPNP_CONFIG_H */
+ 
+diff --git a/upnp/src/genlib/net/http/webserver.c b/upnp/src/genlib/net/http/webserver.c
+index 8991c16..8b2ecf2 100644
+--- a/upnp/src/genlib/net/http/webserver.c
++++ b/upnp/src/genlib/net/http/webserver.c
+@@ -1369,9 +1369,13 @@ static int http_RecvPostMessage(
+ 		if (Fp == NULL)
+ 			return HTTP_INTERNAL_SERVER_ERROR;
+ 	} else {
++#ifdef UPNP_ENABLE_POST_WRITE
+ 		Fp = fopen(filename, "wb");
+ 		if (Fp == NULL)
+ 			return HTTP_UNAUTHORIZED;
++#else
++		return HTTP_NOT_FOUND;
++#endif
+ 	}
+ 	parser->position = POS_ENTITY;
+ 	do {
+-- 
+2.10.2
+

package/libupnp/libupnp.mk

@@ -11,5 +11,7 @@ LIBUPNP_CONF_ENV = ac_cv_lib_compat_ftime=no
 LIBUPNP_INSTALL_STAGING = YES
 LIBUPNP_LICENSE = BSD-3c
 LIBUPNP_LICENSE_FILES = LICENSE
+# configure.ac patched by 0001-Don-t-allow-unhandled-POSTs-to-write-to-the-filesyst.patch
+LIBUPNP_AUTORECONF = YES
 
 $(eval $(autotools-package))