diff options
Diffstat (limited to 'net/netfilter/nft_reject_netdev.c')
| -rw-r--r-- | net/netfilter/nft_reject_netdev.c | 191 |
1 files changed, 191 insertions, 0 deletions
diff --git a/net/netfilter/nft_reject_netdev.c b/net/netfilter/nft_reject_netdev.c new file mode 100644 index 000000000..7865cd8b1 --- /dev/null +++ b/net/netfilter/nft_reject_netdev.c @@ -0,0 +1,191 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (c) 2020 Laura Garcia Liebana <nevola@gmail.com> + * Copyright (c) 2020 Jose M. Guisado <guigom@riseup.net> + */ + +#include <linux/etherdevice.h> +#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> + +static void nft_reject_queue_xmit(struct sk_buff *nskb, struct sk_buff *oldskb) +{ + dev_hard_header(nskb, nskb->dev, ntohs(oldskb->protocol), + eth_hdr(oldskb)->h_source, eth_hdr(oldskb)->h_dest, + nskb->len); + dev_queue_xmit(nskb); +} + +static void nft_reject_netdev_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, dev, hook); + if (!nskb) + return; + + nft_reject_queue_xmit(nskb, oldskb); +} + +static void nft_reject_netdev_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, dev, hook, code); + if (!nskb) + return; + + nft_reject_queue_xmit(nskb, oldskb); +} + +static void nft_reject_netdev_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, dev, hook); + if (!nskb) + return; + + nft_reject_queue_xmit(nskb, oldskb); +} + + +static void nft_reject_netdev_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, dev, hook, code); + if (!nskb) + return; + + nft_reject_queue_xmit(nskb, oldskb); +} + +static void nft_reject_netdev_eval(const struct nft_expr *expr, + struct nft_regs *regs, + const struct nft_pktinfo *pkt) +{ + struct ethhdr *eth = eth_hdr(pkt->skb); + struct nft_reject *priv = nft_expr_priv(expr); + const unsigned char *dest = eth->h_dest; + + if (is_broadcast_ether_addr(dest) || + is_multicast_ether_addr(dest)) + goto out; + + switch (eth->h_proto) { + case htons(ETH_P_IP): + switch (priv->type) { + case NFT_REJECT_ICMP_UNREACH: + nft_reject_netdev_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_netdev_send_v4_tcp_reset(nft_net(pkt), pkt->skb, + nft_in(pkt), + nft_hook(pkt)); + break; + case NFT_REJECT_ICMPX_UNREACH: + nft_reject_netdev_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_netdev_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_netdev_send_v6_tcp_reset(nft_net(pkt), pkt->skb, + nft_in(pkt), + nft_hook(pkt)); + break; + case NFT_REJECT_ICMPX_UNREACH: + nft_reject_netdev_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_netdev_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_NETDEV_INGRESS)); +} + +static struct nft_expr_type nft_reject_netdev_type; +static const struct nft_expr_ops nft_reject_netdev_ops = { + .type = &nft_reject_netdev_type, + .size = NFT_EXPR_SIZE(sizeof(struct nft_reject)), + .eval = nft_reject_netdev_eval, + .init = nft_reject_init, + .dump = nft_reject_dump, + .validate = nft_reject_netdev_validate, + .reduce = NFT_REDUCE_READONLY, +}; + +static struct nft_expr_type nft_reject_netdev_type __read_mostly = { + .family = NFPROTO_NETDEV, + .name = "reject", + .ops = &nft_reject_netdev_ops, + .policy = nft_reject_policy, + .maxattr = NFTA_REJECT_MAX, + .owner = THIS_MODULE, +}; + +static int __init nft_reject_netdev_module_init(void) +{ + return nft_register_expr(&nft_reject_netdev_type); +} + +static void __exit nft_reject_netdev_module_exit(void) +{ + nft_unregister_expr(&nft_reject_netdev_type); +} + +module_init(nft_reject_netdev_module_init); +module_exit(nft_reject_netdev_module_exit); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Laura Garcia Liebana <nevola@gmail.com>"); +MODULE_AUTHOR("Jose M. Guisado <guigom@riseup.net>"); +MODULE_DESCRIPTION("Reject packets from netdev via nftables"); +MODULE_ALIAS_NFT_AF_EXPR(5, "reject"); |