1 files changed, 418 insertions, 0 deletions

diff --git a/net/bridge/netfilter/nft_reject_bridge.c b/net/bridge/netfilter/nft_reject_bridge.c
new file mode 100644
index 000000000..858d84856
--- /dev/null
+++ b/net/bridge/netfilter/nft_reject_bridge.c
@@ -0,0 +1,418 @@
+/*
+ * Copyright (c) 2014 Pablo Neira Ayuso <pablo@netfilter.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/netlink.h>
+#include <linux/netfilter.h>
+#include <linux/netfilter/nf_tables.h>
+#include <net/netfilter/nf_tables.h>
+#include <net/netfilter/nft_reject.h>
+#include <net/netfilter/nf_tables_bridge.h>
+#include <net/netfilter/ipv4/nf_reject.h>
+#include <net/netfilter/ipv6/nf_reject.h>
+#include <linux/ip.h>
+#include <net/ip.h>
+#include <net/ip6_checksum.h>
+#include <linux/netfilter_bridge.h>
+#include <linux/netfilter_ipv6.h>
+#include "../br_private.h"
+
+static void nft_reject_br_push_etherhdr(struct sk_buff *oldskb,
+					struct sk_buff *nskb)
+{
+	struct ethhdr *eth;
+
+	eth = (struct ethhdr *)skb_push(nskb, ETH_HLEN);
+	skb_reset_mac_header(nskb);
+	ether_addr_copy(eth->h_source, eth_hdr(oldskb)->h_dest);
+	ether_addr_copy(eth->h_dest, eth_hdr(oldskb)->h_source);
+	eth->h_proto = eth_hdr(oldskb)->h_proto;
+	skb_pull(nskb, ETH_HLEN);
+}
+
+/* We cannot use oldskb->dev, it can be either bridge device (NF_BRIDGE INPUT)
+ * or the bridge port (NF_BRIDGE PREROUTING).
+ */
+static void nft_reject_br_send_v4_tcp_reset(struct sk_buff *oldskb,
+					    const struct net_device *dev,
+					    int hook)
+{
+	struct sk_buff *nskb;
+	struct iphdr *niph;
+	const struct tcphdr *oth;
+	struct tcphdr _oth;
+
+	if (!nft_bridge_iphdr_validate(oldskb))
+		return;
+
+	oth = nf_reject_ip_tcphdr_get(oldskb, &_oth, hook);
+	if (!oth)
+		return;
+
+	nskb = alloc_skb(sizeof(struct iphdr) + sizeof(struct tcphdr) +
+			 LL_MAX_HEADER, GFP_ATOMIC);
+	if (!nskb)
+		return;
+
+	skb_reserve(nskb, LL_MAX_HEADER);
+	niph = nf_reject_iphdr_put(nskb, oldskb, IPPROTO_TCP,
+				   sysctl_ip_default_ttl);
+	nf_reject_ip_tcphdr_put(nskb, oldskb, oth);
+	niph->ttl	= sysctl_ip_default_ttl;
+	niph->tot_len	= htons(nskb->len);
+	ip_send_check(niph);
+
+	nft_reject_br_push_etherhdr(oldskb, nskb);
+
+	br_deliver(br_port_get_rcu(dev), nskb);
+}
+
+static void nft_reject_br_send_v4_unreach(struct sk_buff *oldskb,
+					  const struct net_device *dev,
+					  int hook, u8 code)
+{
+	struct sk_buff *nskb;
+	struct iphdr *niph;
+	struct icmphdr *icmph;
+	unsigned int len;
+	void *payload;
+	__wsum csum;
+	u8 proto;
+
+	if (oldskb->csum_bad || !nft_bridge_iphdr_validate(oldskb))
+		return;
+
+	/* IP header checks: fragment. */
+	if (ip_hdr(oldskb)->frag_off & htons(IP_OFFSET))
+		return;
+
+	/* RFC says return as much as we can without exceeding 576 bytes. */
+	len = min_t(unsigned int, 536, oldskb->len);
+
+	if (!pskb_may_pull(oldskb, len))
+		return;
+
+	if (pskb_trim_rcsum(oldskb, ntohs(ip_hdr(oldskb)->tot_len)))
+		return;
+
+	if (ip_hdr(oldskb)->protocol == IPPROTO_TCP ||
+	    ip_hdr(oldskb)->protocol == IPPROTO_UDP)
+		proto = ip_hdr(oldskb)->protocol;
+	else
+		proto = 0;
+
+	if (!skb_csum_unnecessary(oldskb) &&
+	    nf_ip_checksum(oldskb, hook, ip_hdrlen(oldskb), proto))
+		return;
+
+	nskb = alloc_skb(sizeof(struct iphdr) + sizeof(struct icmphdr) +
+			 LL_MAX_HEADER + len, GFP_ATOMIC);
+	if (!nskb)
+		return;
+
+	skb_reserve(nskb, LL_MAX_HEADER);
+	niph = nf_reject_iphdr_put(nskb, oldskb, IPPROTO_ICMP,
+				   sysctl_ip_default_ttl);
+
+	skb_reset_transport_header(nskb);
+	icmph = (struct icmphdr *)skb_put(nskb, sizeof(struct icmphdr));
+	memset(icmph, 0, sizeof(*icmph));
+	icmph->type     = ICMP_DEST_UNREACH;
+	icmph->code	= code;
+
+	payload = skb_put(nskb, len);
+	memcpy(payload, skb_network_header(oldskb), len);
+
+	csum = csum_partial((void *)icmph, len + sizeof(struct icmphdr), 0);
+	icmph->checksum = csum_fold(csum);
+
+	niph->tot_len	= htons(nskb->len);
+	ip_send_check(niph);
+
+	nft_reject_br_push_etherhdr(oldskb, nskb);
+
+	br_deliver(br_port_get_rcu(dev), nskb);
+}
+
+static void nft_reject_br_send_v6_tcp_reset(struct net *net,
+					    struct sk_buff *oldskb,
+					    const struct net_device *dev,
+					    int hook)
+{
+	struct sk_buff *nskb;
+	const struct tcphdr *oth;
+	struct tcphdr _oth;
+	unsigned int otcplen;
+	struct ipv6hdr *nip6h;
+
+	if (!nft_bridge_ip6hdr_validate(oldskb))
+		return;
+
+	oth = nf_reject_ip6_tcphdr_get(oldskb, &_oth, &otcplen, hook);
+	if (!oth)
+		return;
+
+	nskb = alloc_skb(sizeof(struct ipv6hdr) + sizeof(struct tcphdr) +
+			 LL_MAX_HEADER, GFP_ATOMIC);
+	if (!nskb)
+		return;
+
+	skb_reserve(nskb, LL_MAX_HEADER);
+	nip6h = nf_reject_ip6hdr_put(nskb, oldskb, IPPROTO_TCP,
+				     net->ipv6.devconf_all->hop_limit);
+	nf_reject_ip6_tcphdr_put(nskb, oldskb, oth, otcplen);
+	nip6h->payload_len = htons(nskb->len - sizeof(struct ipv6hdr));
+
+	nft_reject_br_push_etherhdr(oldskb, nskb);
+
+	br_deliver(br_port_get_rcu(dev), nskb);
+}
+
+static bool reject6_br_csum_ok(struct sk_buff *skb, int hook)
+{
+	const struct ipv6hdr *ip6h = ipv6_hdr(skb);
+	int thoff;
+	__be16 fo;
+	u8 proto = ip6h->nexthdr;
+
+	if (skb->csum_bad)
+		return false;
+
+	if (skb_csum_unnecessary(skb))
+		return true;
+
+	if (ip6h->payload_len &&
+	    pskb_trim_rcsum(skb, ntohs(ip6h->payload_len) + sizeof(*ip6h)))
+		return false;
+
+	thoff = ipv6_skip_exthdr(skb, ((u8*)(ip6h+1) - skb->data), &proto, &fo);
+	if (thoff < 0 || thoff >= skb->len || (fo & htons(~0x7)) != 0)
+		return false;
+
+	return nf_ip6_checksum(skb, hook, thoff, proto) == 0;
+}
+
+static void nft_reject_br_send_v6_unreach(struct net *net,
+					  struct sk_buff *oldskb,
+					  const struct net_device *dev,
+					  int hook, u8 code)
+{
+	struct sk_buff *nskb;
+	struct ipv6hdr *nip6h;
+	struct icmp6hdr *icmp6h;
+	unsigned int len;
+	void *payload;
+
+	if (!nft_bridge_ip6hdr_validate(oldskb))
+		return;
+
+	/* Include "As much of invoking packet as possible without the ICMPv6
+	 * packet exceeding the minimum IPv6 MTU" in the ICMP payload.
+	 */
+	len = min_t(unsigned int, 1220, oldskb->len);
+
+	if (!pskb_may_pull(oldskb, len))
+		return;
+
+	if (!reject6_br_csum_ok(oldskb, hook))
+		return;
+
+	nskb = alloc_skb(sizeof(struct iphdr) + sizeof(struct icmp6hdr) +
+			 LL_MAX_HEADER + len, GFP_ATOMIC);
+	if (!nskb)
+		return;
+
+	skb_reserve(nskb, LL_MAX_HEADER);
+	nip6h = nf_reject_ip6hdr_put(nskb, oldskb, IPPROTO_ICMPV6,
+				     net->ipv6.devconf_all->hop_limit);
+
+	skb_reset_transport_header(nskb);
+	icmp6h = (struct icmp6hdr *)skb_put(nskb, sizeof(struct icmp6hdr));
+	memset(icmp6h, 0, sizeof(*icmp6h));
+	icmp6h->icmp6_type = ICMPV6_DEST_UNREACH;
+	icmp6h->icmp6_code = code;
+
+	payload = skb_put(nskb, len);
+	memcpy(payload, skb_network_header(oldskb), len);
+	nip6h->payload_len = htons(nskb->len - sizeof(struct ipv6hdr));
+
+	icmp6h->icmp6_cksum =
+		csum_ipv6_magic(&nip6h->saddr, &nip6h->daddr,
+				nskb->len - sizeof(struct ipv6hdr),
+				IPPROTO_ICMPV6,
+				csum_partial(icmp6h,
+					     nskb->len - sizeof(struct ipv6hdr),
+					     0));
+
+	nft_reject_br_push_etherhdr(oldskb, nskb);
+
+	br_deliver(br_port_get_rcu(dev), nskb);
+}
+
+static void nft_reject_bridge_eval(const struct nft_expr *expr,
+				   struct nft_regs *regs,
+				   const struct nft_pktinfo *pkt)
+{
+	struct nft_reject *priv = nft_expr_priv(expr);
+	struct net *net = dev_net((pkt->in != NULL) ? pkt->in : pkt->out);
+	const unsigned char *dest = eth_hdr(pkt->skb)->h_dest;
+
+	if (is_broadcast_ether_addr(dest) ||
+	    is_multicast_ether_addr(dest))
+		goto out;
+
+	switch (eth_hdr(pkt->skb)->h_proto) {
+	case htons(ETH_P_IP):
+		switch (priv->type) {
+		case NFT_REJECT_ICMP_UNREACH:
+			nft_reject_br_send_v4_unreach(pkt->skb, pkt->in,
+						      pkt->ops->hooknum,
+						      priv->icmp_code);
+			break;
+		case NFT_REJECT_TCP_RST:
+			nft_reject_br_send_v4_tcp_reset(pkt->skb, pkt->in,
+							pkt->ops->hooknum);
+			break;
+		case NFT_REJECT_ICMPX_UNREACH:
+			nft_reject_br_send_v4_unreach(pkt->skb, pkt->in,
+						      pkt->ops->hooknum,
+						      nft_reject_icmp_code(priv->icmp_code));
+			break;
+		}
+		break;
+	case htons(ETH_P_IPV6):
+		switch (priv->type) {
+		case NFT_REJECT_ICMP_UNREACH:
+			nft_reject_br_send_v6_unreach(net, pkt->skb, pkt->in,
+						      pkt->ops->hooknum,
+						      priv->icmp_code);
+			break;
+		case NFT_REJECT_TCP_RST:
+			nft_reject_br_send_v6_tcp_reset(net, pkt->skb, pkt->in,
+							pkt->ops->hooknum);
+			break;
+		case NFT_REJECT_ICMPX_UNREACH:
+			nft_reject_br_send_v6_unreach(net, pkt->skb, pkt->in,
+						      pkt->ops->hooknum,
+						      nft_reject_icmpv6_code(priv->icmp_code));
+			break;
+		}
+		break;
+	default:
+		/* No explicit way to reject this protocol, drop it. */
+		break;
+	}
+out:
+	regs->verdict.code = NF_DROP;
+}
+
+static int nft_reject_bridge_validate(const struct nft_ctx *ctx,
+				      const struct nft_expr *expr,
+				      const struct nft_data **data)
+{
+	return nft_chain_validate_hooks(ctx->chain, (1 << NF_BR_PRE_ROUTING) |
+						    (1 << NF_BR_LOCAL_IN));
+}
+
+static int nft_reject_bridge_init(const struct nft_ctx *ctx,
+				  const struct nft_expr *expr,
+				  const struct nlattr * const tb[])
+{
+	struct nft_reject *priv = nft_expr_priv(expr);
+	int icmp_code, err;
+
+	err = nft_reject_bridge_validate(ctx, expr, NULL);
+	if (err < 0)
+		return err;
+
+	if (tb[NFTA_REJECT_TYPE] == NULL)
+		return -EINVAL;
+
+	priv->type = ntohl(nla_get_be32(tb[NFTA_REJECT_TYPE]));
+	switch (priv->type) {
+	case NFT_REJECT_ICMP_UNREACH:
+	case NFT_REJECT_ICMPX_UNREACH:
+		if (tb[NFTA_REJECT_ICMP_CODE] == NULL)
+			return -EINVAL;
+
+		icmp_code = nla_get_u8(tb[NFTA_REJECT_ICMP_CODE]);
+		if (priv->type == NFT_REJECT_ICMPX_UNREACH &&
+		    icmp_code > NFT_REJECT_ICMPX_MAX)
+			return -EINVAL;
+
+		priv->icmp_code = icmp_code;
+		break;
+	case NFT_REJECT_TCP_RST:
+		break;
+	default:
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static int nft_reject_bridge_dump(struct sk_buff *skb,
+				  const struct nft_expr *expr)
+{
+	const struct nft_reject *priv = nft_expr_priv(expr);
+
+	if (nla_put_be32(skb, NFTA_REJECT_TYPE, htonl(priv->type)))
+		goto nla_put_failure;
+
+	switch (priv->type) {
+	case NFT_REJECT_ICMP_UNREACH:
+	case NFT_REJECT_ICMPX_UNREACH:
+		if (nla_put_u8(skb, NFTA_REJECT_ICMP_CODE, priv->icmp_code))
+			goto nla_put_failure;
+		break;
+	default:
+		break;
+	}
+
+	return 0;
+
+nla_put_failure:
+	return -1;
+}
+
+static struct nft_expr_type nft_reject_bridge_type;
+static const struct nft_expr_ops nft_reject_bridge_ops = {
+	.type		= &nft_reject_bridge_type,
+	.size		= NFT_EXPR_SIZE(sizeof(struct nft_reject)),
+	.eval		= nft_reject_bridge_eval,
+	.init		= nft_reject_bridge_init,
+	.dump		= nft_reject_bridge_dump,
+	.validate	= nft_reject_bridge_validate,
+};
+
+static struct nft_expr_type nft_reject_bridge_type __read_mostly = {
+	.family		= NFPROTO_BRIDGE,
+	.name		= "reject",
+	.ops		= &nft_reject_bridge_ops,
+	.policy		= nft_reject_policy,
+	.maxattr	= NFTA_REJECT_MAX,
+	.owner		= THIS_MODULE,
+};
+
+static int __init nft_reject_bridge_module_init(void)
+{
+	return nft_register_expr(&nft_reject_bridge_type);
+}
+
+static void __exit nft_reject_bridge_module_exit(void)
+{
+	nft_unregister_expr(&nft_reject_bridge_type);
+}
+
+module_init(nft_reject_bridge_module_init);
+module_exit(nft_reject_bridge_module_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
+MODULE_ALIAS_NFT_AF_EXPR(AF_BRIDGE, "reject");