From 2dbfd733c34311df6217da809c0045c195ba8b9e Mon Sep 17 00:00:00 2001
From: Jo-Philipp Wich <jow@openwrt.org>
Date: Mon, 3 Jun 2013 17:43:06 +0200
Subject: [PATCH] Do not let libxtables implicitely load extensions, do it
 directly from fw3 and track the loaded objects for properly closing when
 destroying the handle.

---
 CMakeLists.txt |  2 +-
 iptables.c     | 71 +++++++++++++++++++++++++++++++++++++++++++++-----
 iptables.h     |  4 +++
 3 files changed, 69 insertions(+), 8 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index cf7ee96..4a85e07 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -38,7 +38,7 @@ ELSE()
 ENDIF()
 
 ADD_EXECUTABLE(firewall3 main.c options.c defaults.c zones.c forwards.c rules.c redirects.c utils.c ubus.c ipsets.c includes.c iptables.c)
-TARGET_LINK_LIBRARIES(firewall3 uci ubox ubus xtables m ${iptc_libs} ${ext_libs})
+TARGET_LINK_LIBRARIES(firewall3 uci ubox ubus xtables m dl ${iptc_libs} ${ext_libs})
 
 SET(CMAKE_INSTALL_PREFIX /usr)
 
diff --git a/iptables.c b/iptables.c
index 21c96b4..2fc8d36 100644
--- a/iptables.c
+++ b/iptables.c
@@ -312,6 +312,17 @@ fw3_ipt_commit(struct fw3_ipt_handle *h)
 			fprintf(stderr, "iptc_commit(): %s\n", iptc_strerror(errno));
 	}
 
+	if (h->libv)
+	{
+		while (h->libc > 0)
+		{
+			h->libc--;
+			dlclose(h->libv[h->libc]);
+		}
+
+		free(h->libv);
+	}
+
 	free(h);
 }
 
@@ -354,10 +365,45 @@ get_protoname(struct fw3_ipt_rule *r)
 	return NULL;
 }
 
+static bool
+load_extension(struct fw3_ipt_handle *h, const char *name)
+{
+	char path[256];
+	void *lib, **tmp;
+	const char *pfx = (h->family == FW3_FAMILY_V6) ? "libip6t" : "libipt";
+
+	snprintf(path, sizeof(path), "/usr/lib/iptables/libxt_%s.so", name);
+	if (!(lib = dlopen(path, RTLD_NOW)))
+	{
+		snprintf(path, sizeof(path), "/usr/lib/iptables/%s_%s.so", pfx, name);
+		lib = dlopen(path, RTLD_NOW);
+	}
+
+	if (!lib)
+		return false;
+
+	tmp = realloc(h->libv, sizeof(lib) * (h->libc + 1));
+
+	if (!tmp)
+		return false;
+
+	h->libv = tmp;
+	h->libv[h->libc++] = lib;
+
+	return true;
+}
+
 static struct xtables_match *
 find_match(struct fw3_ipt_rule *r, const char *name)
 {
-	return xtables_find_match(name, XTF_TRY_LOAD, &r->matches);
+	struct xtables_match *m;
+
+	m = xtables_find_match(name, XTF_DONT_LOAD, &r->matches);
+
+	if (!m && load_extension(r->h, name))
+		m = xtables_find_match(name, XTF_DONT_LOAD, &r->matches);
+
+	return m;
 }
 
 static void
@@ -416,6 +462,22 @@ load_protomatch(struct fw3_ipt_rule *r)
 	return find_match(r, pname);
 }
 
+static struct xtables_target *
+find_target(struct fw3_ipt_rule *r, const char *name)
+{
+	struct xtables_target *t;
+
+	if (is_chain(r->h, name))
+		return xtables_find_target(XT_STANDARD_TARGET, XTF_LOAD_MUST_SUCCEED);
+
+	t = xtables_find_target(name, XTF_DONT_LOAD);
+
+	if (!t && load_extension(r->h, name))
+		t = xtables_find_target(name, XTF_DONT_LOAD);
+
+	return t;
+}
+
 static struct xtables_target *
 get_target(struct fw3_ipt_rule *r, const char *name)
 {
@@ -423,12 +485,7 @@ get_target(struct fw3_ipt_rule *r, const char *name)
 	struct xtables_target *t;
 	struct xtables_globals *g;
 
-	bool chain = is_chain(r->h, name);
-
-	if (chain)
-		t = xtables_find_target(XT_STANDARD_TARGET, XTF_LOAD_MUST_SUCCEED);
-	else
-		t = xtables_find_target(name, XTF_TRY_LOAD);
+	t = find_target(r, name);
 
 	if (!t)
 		return NULL;
diff --git a/iptables.h b/iptables.h
index 3237a4a..e86162d 100644
--- a/iptables.h
+++ b/iptables.h
@@ -23,6 +23,7 @@
 #include <libiptc/libip6tc.h>
 #include <xtables.h>
 
+#include <dlfcn.h>
 #include <unistd.h>
 #include <getopt.h>
 #include <sys/utsname.h>
@@ -87,6 +88,9 @@ struct fw3_ipt_handle {
 	enum fw3_family family;
 	enum fw3_table table;
 	void *handle;
+
+	int libc;
+	void **libv;
 };
 
 struct fw3_ipt_rule {
-- 
2.25.1