netfilter: factor out packet duplication for IPv4/IPv6
Extracted from the xtables TEE target. This creates two new modules for IPv4
and IPv6 that are shared between the TEE target and the new nf_tables dup
expressions.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
diff --git a/net/netfilter/xt_TEE.c b/net/netfilter/xt_TEE.c
index 0ed9fb6..49fee6a 100644
--- a/net/netfilter/xt_TEE.c
+++ b/net/netfilter/xt_TEE.c
@@ -10,23 +10,14 @@
* modify it under the terms of the GNU General Public License
* version 2 or later, as published by the Free Software Foundation.
*/
-#include <linux/ip.h>
#include <linux/module.h>
-#include <linux/percpu.h>
-#include <linux/route.h>
#include <linux/skbuff.h>
-#include <linux/notifier.h>
-#include <net/checksum.h>
-#include <net/icmp.h>
-#include <net/ip.h>
-#include <net/ipv6.h>
-#include <net/ip6_route.h>
-#include <net/route.h>
+#include <linux/route.h>
#include <linux/netfilter/x_tables.h>
+#include <net/route.h>
+#include <net/netfilter/ipv4/nf_dup_ipv4.h>
+#include <net/netfilter/ipv6/nf_dup_ipv6.h>
#include <linux/netfilter/xt_TEE.h>
-#if IS_ENABLED(CONFIG_NF_CONNTRACK)
-#include <net/netfilter/nf_conntrack.h>
-#endif
struct xt_tee_priv {
struct notifier_block notifier;
@@ -36,161 +27,24 @@
static const union nf_inet_addr tee_zero_address;
-static struct net *pick_net(struct sk_buff *skb)
-{
-#ifdef CONFIG_NET_NS
- const struct dst_entry *dst;
-
- if (skb->dev != NULL)
- return dev_net(skb->dev);
- dst = skb_dst(skb);
- if (dst != NULL && dst->dev != NULL)
- return dev_net(dst->dev);
-#endif
- return &init_net;
-}
-
-static bool
-tee_tg_route4(struct sk_buff *skb, const struct xt_tee_tginfo *info)
-{
- const struct iphdr *iph = ip_hdr(skb);
- struct net *net = pick_net(skb);
- struct rtable *rt;
- struct flowi4 fl4;
-
- memset(&fl4, 0, sizeof(fl4));
- if (info->priv) {
- if (info->priv->oif == -1)
- return false;
- fl4.flowi4_oif = info->priv->oif;
- }
- fl4.daddr = info->gw.ip;
- fl4.flowi4_tos = RT_TOS(iph->tos);
- fl4.flowi4_scope = RT_SCOPE_UNIVERSE;
- fl4.flowi4_flags = FLOWI_FLAG_KNOWN_NH;
- rt = ip_route_output_key(net, &fl4);
- if (IS_ERR(rt))
- return false;
-
- skb_dst_drop(skb);
- skb_dst_set(skb, &rt->dst);
- skb->dev = rt->dst.dev;
- skb->protocol = htons(ETH_P_IP);
- return true;
-}
-
static unsigned int
tee_tg4(struct sk_buff *skb, const struct xt_action_param *par)
{
const struct xt_tee_tginfo *info = par->targinfo;
- struct iphdr *iph;
- if (__this_cpu_read(nf_skb_duplicated))
- 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
- * happened. The copy should be independently delivered to the TEE
- * --gateway.
- */
- skb = pskb_copy(skb, GFP_ATOMIC);
- if (skb == NULL)
- return XT_CONTINUE;
+ nf_dup_ipv4(skb, par->hooknum, &info->gw.in, info->priv->oif);
-#if IS_ENABLED(CONFIG_NF_CONNTRACK)
- /* Avoid counting cloned packets towards the original connection. */
- nf_conntrack_put(skb->nfct);
- skb->nfct = &nf_ct_untracked_get()->ct_general;
- skb->nfctinfo = IP_CT_NEW;
- nf_conntrack_get(skb->nfct);
-#endif
- /*
- * If we are in PREROUTING/INPUT, the checksum must be recalculated
- * since the length could have changed as a result of defragmentation.
- *
- * We also decrease the TTL to mitigate potential TEE loops
- * between two hosts.
- *
- * Set %IP_DF so that the original source is notified of a potentially
- * decreased MTU on the clone route. IPv6 does this too.
- */
- iph = ip_hdr(skb);
- iph->frag_off |= htons(IP_DF);
- if (par->hooknum == NF_INET_PRE_ROUTING ||
- par->hooknum == NF_INET_LOCAL_IN)
- --iph->ttl;
- ip_send_check(iph);
-
- if (tee_tg_route4(skb, info)) {
- __this_cpu_write(nf_skb_duplicated, true);
- ip_local_out(skb);
- __this_cpu_write(nf_skb_duplicated, false);
- } else {
- kfree_skb(skb);
- }
return XT_CONTINUE;
}
#if IS_ENABLED(CONFIG_IPV6)
-static bool
-tee_tg_route6(struct sk_buff *skb, const struct xt_tee_tginfo *info)
-{
- const struct ipv6hdr *iph = ipv6_hdr(skb);
- struct net *net = pick_net(skb);
- struct dst_entry *dst;
- struct flowi6 fl6;
-
- memset(&fl6, 0, sizeof(fl6));
- if (info->priv) {
- if (info->priv->oif == -1)
- return false;
- fl6.flowi6_oif = info->priv->oif;
- }
- fl6.daddr = info->gw.in6;
- fl6.flowlabel = ((iph->flow_lbl[0] & 0xF) << 16) |
- (iph->flow_lbl[1] << 8) | iph->flow_lbl[2];
- fl6.flowi6_flags = FLOWI_FLAG_KNOWN_NH;
- dst = ip6_route_output(net, NULL, &fl6);
- if (dst->error) {
- dst_release(dst);
- return false;
- }
- skb_dst_drop(skb);
- skb_dst_set(skb, dst);
- skb->dev = dst->dev;
- skb->protocol = htons(ETH_P_IPV6);
- return true;
-}
-
static unsigned int
tee_tg6(struct sk_buff *skb, const struct xt_action_param *par)
{
const struct xt_tee_tginfo *info = par->targinfo;
- if (__this_cpu_read(nf_skb_duplicated))
- return XT_CONTINUE;
- skb = pskb_copy(skb, GFP_ATOMIC);
- if (skb == NULL)
- return XT_CONTINUE;
+ nf_dup_ipv6(skb, par->hooknum, &info->gw.in6, info->priv->oif);
-#if IS_ENABLED(CONFIG_NF_CONNTRACK)
- nf_conntrack_put(skb->nfct);
- skb->nfct = &nf_ct_untracked_get()->ct_general;
- skb->nfctinfo = IP_CT_NEW;
- nf_conntrack_get(skb->nfct);
-#endif
- if (par->hooknum == NF_INET_PRE_ROUTING ||
- par->hooknum == NF_INET_LOCAL_IN) {
- struct ipv6hdr *iph = ipv6_hdr(skb);
- --iph->hop_limit;
- }
- if (tee_tg_route6(skb, info)) {
- __this_cpu_write(nf_skb_duplicated, true);
- ip6_local_out(skb);
- __this_cpu_write(nf_skb_duplicated, false);
- } else {
- kfree_skb(skb);
- }
return XT_CONTINUE;
}
#endif