From bbde9fc1824aab58bc78c084163007dd6c03fe5b Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Sun, 31 May 2015 17:54:44 +0200 Subject: 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 --- net/netfilter/Kconfig | 2 + net/netfilter/xt_TEE.c | 158 ++----------------------------------------------- 2 files changed, 8 insertions(+), 152 deletions(-) (limited to 'net/netfilter') diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig index 6eae69a..3e1b4ab 100644 --- a/net/netfilter/Kconfig +++ b/net/netfilter/Kconfig @@ -867,6 +867,8 @@ config NETFILTER_XT_TARGET_TEE depends on NETFILTER_ADVANCED depends on IPV6 || IPV6=n depends on !NF_CONNTRACK || NF_CONNTRACK + select NF_DUP_IPV4 + select NF_DUP_IPV6 if IP6_NF_IPTABLES ---help--- This option adds a "TEE" target with which a packet can be cloned and this clone be rerouted to another nexthop. 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 #include -#include -#include #include -#include -#include -#include -#include -#include -#include -#include +#include #include +#include +#include +#include #include -#if IS_ENABLED(CONFIG_NF_CONNTRACK) -#include -#endif struct xt_tee_priv { struct notifier_block notifier; @@ -36,161 +27,24 @@ struct xt_tee_priv { 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; - -#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); + nf_dup_ipv4(skb, par->hooknum, &info->gw.in, info->priv->oif); - 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 -- cgit v1.1