| // SPDX-License-Identifier: GPL-2.0-only |
| /* |
| * Copyright (c) 2014 Pablo Neira Ayuso <pablo@netfilter.org> |
| */ |
| |
| #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/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 = 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); |
| |
| if (skb_vlan_tag_present(oldskb)) { |
| u16 vid = skb_vlan_tag_get(oldskb); |
| |
| __vlan_hwaccel_put_tag(nskb, oldskb->vlan_proto, vid); |
| } |
| } |
| |
| /* 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 net *net, |
| struct sk_buff *oldskb, |
| const struct net_device *dev, |
| int hook) |
| { |
| struct sk_buff *nskb; |
| |
| nskb = nf_reject_skb_v4_tcp_reset(net, oldskb, NULL, hook); |
| if (!nskb) |
| return; |
| |
| nft_reject_br_push_etherhdr(oldskb, nskb); |
| |
| br_forward(br_port_get_rcu(dev), nskb, false, true); |
| } |
| |
| static void nft_reject_br_send_v4_unreach(struct net *net, |
| struct sk_buff *oldskb, |
| const struct net_device *dev, |
| int hook, u8 code) |
| { |
| struct sk_buff *nskb; |
| |
| nskb = nf_reject_skb_v4_unreach(net, oldskb, NULL, hook, code); |
| if (!nskb) |
| return; |
| |
| nft_reject_br_push_etherhdr(oldskb, nskb); |
| |
| br_forward(br_port_get_rcu(dev), nskb, false, true); |
| } |
| |
| 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; |
| |
| nskb = nf_reject_skb_v6_tcp_reset(net, oldskb, NULL, hook); |
| if (!nskb) |
| return; |
| |
| nft_reject_br_push_etherhdr(oldskb, nskb); |
| |
| br_forward(br_port_get_rcu(dev), nskb, false, true); |
| } |
| |
| |
| 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; |
| |
| nskb = nf_reject_skb_v6_unreach(net, oldskb, NULL, hook, code); |
| if (!nskb) |
| return; |
| |
| nft_reject_br_push_etherhdr(oldskb, nskb); |
| |
| br_forward(br_port_get_rcu(dev), nskb, false, true); |
| } |
| |
| 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); |
| 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(nft_net(pkt), pkt->skb, |
| nft_in(pkt), |
| nft_hook(pkt), |
| priv->icmp_code); |
| break; |
| case NFT_REJECT_TCP_RST: |
| nft_reject_br_send_v4_tcp_reset(nft_net(pkt), pkt->skb, |
| nft_in(pkt), |
| nft_hook(pkt)); |
| break; |
| case NFT_REJECT_ICMPX_UNREACH: |
| nft_reject_br_send_v4_unreach(nft_net(pkt), pkt->skb, |
| nft_in(pkt), |
| nft_hook(pkt), |
| 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(nft_net(pkt), pkt->skb, |
| nft_in(pkt), |
| nft_hook(pkt), |
| priv->icmp_code); |
| break; |
| case NFT_REJECT_TCP_RST: |
| nft_reject_br_send_v6_tcp_reset(nft_net(pkt), pkt->skb, |
| nft_in(pkt), |
| nft_hook(pkt)); |
| break; |
| case NFT_REJECT_ICMPX_UNREACH: |
| nft_reject_br_send_v6_unreach(nft_net(pkt), pkt->skb, |
| nft_in(pkt), |
| nft_hook(pkt), |
| 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 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_init, |
| .dump = nft_reject_dump, |
| .validate = nft_reject_bridge_validate, |
| .reduce = NFT_REDUCE_READONLY, |
| }; |
| |
| 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"); |
| MODULE_DESCRIPTION("Reject packets from bridge via nftables"); |