netfilter: xt_TEE: have cloned packet travel through Xtables too
Since Xtables is now reentrant/nestable, the cloned packet can also go
through Xtables and be subject to rules itself.
Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>
diff --git a/net/netfilter/xt_TEE.c b/net/netfilter/xt_TEE.c
index b3d7301..842e701 100644
--- a/net/netfilter/xt_TEE.c
+++ b/net/netfilter/xt_TEE.c
@@ -12,6 +12,7 @@
*/
#include <linux/ip.h>
#include <linux/module.h>
+#include <linux/percpu.h>
#include <linux/route.h>
#include <linux/skbuff.h>
#include <net/checksum.h>
@@ -32,6 +33,7 @@
#endif
static const union nf_inet_addr tee_zero_address;
+static DEFINE_PER_CPU(bool, tee_active);
static struct net *pick_net(struct sk_buff *skb)
{
@@ -91,6 +93,8 @@
const struct xt_tee_tginfo *info = par->targinfo;
struct iphdr *iph;
+ if (percpu_read(tee_active))
+ return XT_CONTINUE;
/*
* Copy the skb, and route the copy. Will later return %XT_CONTINUE for
* the original skb, which should continue on its way as if nothing has
@@ -125,24 +129,13 @@
--iph->ttl;
ip_send_check(iph);
- /*
- * Xtables is not reentrant currently, so a choice has to be made:
- * 1. return absolute verdict for the original and let the cloned
- * packet travel through the chains
- * 2. let the original continue travelling and not pass the clone
- * to Xtables.
- * #2 is chosen. Normally, we would use ip_local_out for the clone.
- * Because iph->check is already correct and we don't pass it to
- * Xtables anyway, a shortcut to dst_output [forwards to ip_output] can
- * be taken. %IPSKB_REROUTED needs to be set so that ip_output does not
- * invoke POSTROUTING on the cloned packet.
- */
- IPCB(skb)->flags |= IPSKB_REROUTED;
- if (tee_tg_route4(skb, info))
- ip_output(skb);
- else
+ if (tee_tg_route4(skb, info)) {
+ percpu_write(tee_active, true);
+ ip_local_out(skb);
+ percpu_write(tee_active, false);
+ } else {
kfree_skb(skb);
-
+ }
return XT_CONTINUE;
}
@@ -177,6 +170,8 @@
{
const struct xt_tee_tginfo *info = par->targinfo;
+ if (percpu_read(tee_active))
+ return XT_CONTINUE;
skb = pskb_copy(skb, GFP_ATOMIC);
if (skb == NULL)
return XT_CONTINUE;
@@ -192,12 +187,13 @@
struct ipv6hdr *iph = ipv6_hdr(skb);
--iph->hop_limit;
}
- IP6CB(skb)->flags |= IP6SKB_REROUTED;
- if (tee_tg_route6(skb, info))
- ip6_output(skb);
- else
+ if (tee_tg_route6(skb, info)) {
+ percpu_write(tee_active, true);
+ ip6_local_out(skb);
+ percpu_write(tee_active, false);
+ } else {
kfree_skb(skb);
-
+ }
return XT_CONTINUE;
}
#endif /* WITH_IPV6 */