REJECT statement can be only used in INPUT, FORWARD and OUTPUT
chains. This patch adds support of REJECT, both icmp and tcp
reset, at PREROUTING stage.
The need for this patch becomes from the requirement of some
forwarding devices to reject traffic before the natting and
routing decisions.
It is supported ipv4, ipv6 and inet families for nft
infrastructure.
Signed-off-by: Laura Garcia Liebana <nevola@xxxxxxxxx>
---
net/ipv4/netfilter/nf_reject_ipv4.c | 18 ++++++++++++++++++
net/ipv6/netfilter/nf_reject_ipv6.c | 21 +++++++++++++++++++++
net/netfilter/nft_reject.c | 3 ++-
3 files changed, 41 insertions(+), 1 deletion(-)
diff --git a/net/ipv4/netfilter/nf_reject_ipv4.c b/net/ipv4/netfilter/nf_reject_ipv4.c
index 2361fdac2c43..c6b46b7bca8b 100644
--- a/net/ipv4/netfilter/nf_reject_ipv4.c
+++ b/net/ipv4/netfilter/nf_reject_ipv4.c
@@ -96,6 +96,18 @@ void nf_reject_ip_tcphdr_put(struct sk_buff *nskb, const struct sk_buff *oldskb,
}
EXPORT_SYMBOL_GPL(nf_reject_ip_tcphdr_put);
+static void nf_reject_fill_skb_dst(struct sk_buff *skb_in)
+{
+ struct dst_entry *dst = NULL;
+ struct flowi fl;
+ struct flowi4 *fl4 = &fl.u.ip4;
+
+ memset(fl4, 0, sizeof(*fl4));
+ fl4->daddr = ip_hdr(skb_in)->saddr;
+ nf_route(dev_net(skb_in->dev), &dst, &fl, false, AF_INET);
+ skb_dst_set(skb_in, dst);
+}
+
/* Send RST reply */
void nf_send_reset(struct net *net, struct sk_buff *oldskb, int hook)
{
@@ -109,6 +121,9 @@ void nf_send_reset(struct net *net, struct sk_buff *oldskb, int hook)
if (!oth)
return;
+ if (hook == NF_INET_PRE_ROUTING)
+ nf_reject_fill_skb_dst(oldskb);
+
if (skb_rtable(oldskb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
return;
@@ -175,6 +190,9 @@ void nf_send_unreach(struct sk_buff *skb_in, int code, int hook)
if (iph->frag_off & htons(IP_OFFSET))
return;
+ if (hook == NF_INET_PRE_ROUTING)
+ nf_reject_fill_skb_dst(skb_in);
+
if (skb_csum_unnecessary(skb_in) || !nf_reject_verify_csum(proto)) {
icmp_send(skb_in, ICMP_DEST_UNREACH, code, 0);
return;
diff --git a/net/ipv6/netfilter/nf_reject_ipv6.c b/net/ipv6/netfilter/nf_reject_ipv6.c
index 5fae66f66671..d59b38a16eaa 100644
--- a/net/ipv6/netfilter/nf_reject_ipv6.c
+++ b/net/ipv6/netfilter/nf_reject_ipv6.c
@@ -126,6 +126,18 @@ void nf_reject_ip6_tcphdr_put(struct sk_buff *nskb,
}
EXPORT_SYMBOL_GPL(nf_reject_ip6_tcphdr_put);
+static void nf_reject6_fill_skb_dst(struct sk_buff *skb_in)
+{
+ struct dst_entry *dst = NULL;
+ struct flowi fl;
+ struct flowi6 *fl6 = &fl.u.ip6;
+
+ memset(fl6, 0, sizeof(*fl6));
+ fl6->daddr = ipv6_hdr(skb_in)->saddr;
+ nf_route(dev_net(skb_in->dev), &dst, &fl, false, AF_INET6);
+ skb_dst_set(skb_in, dst);
+}
+
void nf_send_reset6(struct net *net, struct sk_buff *oldskb, int hook)
{
struct net_device *br_indev __maybe_unused;
@@ -154,6 +166,12 @@ void nf_send_reset6(struct net *net, struct sk_buff *oldskb, int hook)
fl6.daddr = oip6h->saddr;
fl6.fl6_sport = otcph->dest;
fl6.fl6_dport = otcph->source;
+
+ if (hook == NF_INET_PRE_ROUTING) {
+ nf_route(dev_net(oldskb->dev), &dst, flowi6_to_flowi(&fl6), false, AF_INET6);
+ skb_dst_set(oldskb, dst);
+ }
+
fl6.flowi6_oif = l3mdev_master_ifindex(skb_dst(oldskb)->dev);
fl6.flowi6_mark = IP6_REPLY_MARK(net, oldskb->mark);
security_skb_classify_flow(oldskb, flowi6_to_flowi(&fl6));
@@ -245,6 +263,9 @@ void nf_send_unreach6(struct net *net, struct sk_buff *skb_in,
if (hooknum == NF_INET_LOCAL_OUT && skb_in->dev == NULL)
skb_in->dev = net->loopback_dev;
+ if (hooknum == NF_INET_PRE_ROUTING)
+ nf_reject6_fill_skb_dst(skb_in);
+
icmpv6_send(skb_in, ICMPV6_DEST_UNREACH, code, 0);
}
EXPORT_SYMBOL_GPL(nf_send_unreach6);
diff --git a/net/netfilter/nft_reject.c b/net/netfilter/nft_reject.c
index 00f865fb80ca..5eac28269bdb 100644
--- a/net/netfilter/nft_reject.c
+++ b/net/netfilter/nft_reject.c
@@ -30,7 +30,8 @@ int nft_reject_validate(const struct nft_ctx *ctx,
return nft_chain_validate_hooks(ctx->chain,
(1 << NF_INET_LOCAL_IN) |
(1 << NF_INET_FORWARD) |
- (1 << NF_INET_LOCAL_OUT));
+ (1 << NF_INET_LOCAL_OUT) |
+ (1 << NF_INET_PRE_ROUTING));
}
EXPORT_SYMBOL_GPL(nft_reject_validate);
--
2.20.1
