1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (c) 2015 Pablo Neira Ayuso <pablo@netfilter.org> 4 */ 5 6 #include <linux/kernel.h> 7 #include <linux/init.h> 8 #include <linux/module.h> 9 #include <linux/netlink.h> 10 #include <linux/netfilter.h> 11 #include <linux/netfilter/nf_tables.h> 12 #include <linux/ip.h> 13 #include <linux/ipv6.h> 14 #include <net/netfilter/nf_tables.h> 15 #include <net/netfilter/nf_tables_offload.h> 16 #include <net/netfilter/nf_dup_netdev.h> 17 #include <net/neighbour.h> 18 #include <net/ip.h> 19 20 struct nft_fwd_netdev { 21 u8 sreg_dev; 22 }; 23 24 static void nft_fwd_netdev_eval(const struct nft_expr *expr, 25 struct nft_regs *regs, 26 const struct nft_pktinfo *pkt) 27 { 28 struct nft_fwd_netdev *priv = nft_expr_priv(expr); 29 int oif = regs->data[priv->sreg_dev]; 30 struct sk_buff *skb = pkt->skb; 31 32 /* This is used by ifb only. */ 33 skb->skb_iif = skb->dev->ifindex; 34 skb_set_redirected(skb, nft_hook(pkt) == NF_NETDEV_INGRESS); 35 36 nf_fwd_netdev_egress(pkt, oif); 37 regs->verdict.code = NF_STOLEN; 38 } 39 40 static const struct nla_policy nft_fwd_netdev_policy[NFTA_FWD_MAX + 1] = { 41 [NFTA_FWD_SREG_DEV] = { .type = NLA_U32 }, 42 [NFTA_FWD_SREG_ADDR] = { .type = NLA_U32 }, 43 [NFTA_FWD_NFPROTO] = { .type = NLA_U32 }, 44 }; 45 46 static int nft_fwd_netdev_init(const struct nft_ctx *ctx, 47 const struct nft_expr *expr, 48 const struct nlattr * const tb[]) 49 { 50 struct nft_fwd_netdev *priv = nft_expr_priv(expr); 51 52 if (tb[NFTA_FWD_SREG_DEV] == NULL) 53 return -EINVAL; 54 55 return nft_parse_register_load(tb[NFTA_FWD_SREG_DEV], &priv->sreg_dev, 56 sizeof(int)); 57 } 58 59 static int nft_fwd_netdev_dump(struct sk_buff *skb, const struct nft_expr *expr) 60 { 61 struct nft_fwd_netdev *priv = nft_expr_priv(expr); 62 63 if (nft_dump_register(skb, NFTA_FWD_SREG_DEV, priv->sreg_dev)) 64 goto nla_put_failure; 65 66 return 0; 67 68 nla_put_failure: 69 return -1; 70 } 71 72 static int nft_fwd_netdev_offload(struct nft_offload_ctx *ctx, 73 struct nft_flow_rule *flow, 74 const struct nft_expr *expr) 75 { 76 const struct nft_fwd_netdev *priv = nft_expr_priv(expr); 77 int oif = ctx->regs[priv->sreg_dev].data.data[0]; 78 79 return nft_fwd_dup_netdev_offload(ctx, flow, FLOW_ACTION_REDIRECT, oif); 80 } 81 82 struct nft_fwd_neigh { 83 u8 sreg_dev; 84 u8 sreg_addr; 85 u8 nfproto; 86 }; 87 88 static void nft_fwd_neigh_eval(const struct nft_expr *expr, 89 struct nft_regs *regs, 90 const struct nft_pktinfo *pkt) 91 { 92 struct nft_fwd_neigh *priv = nft_expr_priv(expr); 93 void *addr = ®s->data[priv->sreg_addr]; 94 int oif = regs->data[priv->sreg_dev]; 95 unsigned int verdict = NF_STOLEN; 96 struct sk_buff *skb = pkt->skb; 97 struct net_device *dev; 98 int neigh_table; 99 100 switch (priv->nfproto) { 101 case NFPROTO_IPV4: { 102 struct iphdr *iph; 103 104 if (skb->protocol != htons(ETH_P_IP)) { 105 verdict = NFT_BREAK; 106 goto out; 107 } 108 if (skb_try_make_writable(skb, sizeof(*iph))) { 109 verdict = NF_DROP; 110 goto out; 111 } 112 iph = ip_hdr(skb); 113 ip_decrease_ttl(iph); 114 neigh_table = NEIGH_ARP_TABLE; 115 break; 116 } 117 case NFPROTO_IPV6: { 118 struct ipv6hdr *ip6h; 119 120 if (skb->protocol != htons(ETH_P_IPV6)) { 121 verdict = NFT_BREAK; 122 goto out; 123 } 124 if (skb_try_make_writable(skb, sizeof(*ip6h))) { 125 verdict = NF_DROP; 126 goto out; 127 } 128 ip6h = ipv6_hdr(skb); 129 ip6h->hop_limit--; 130 neigh_table = NEIGH_ND_TABLE; 131 break; 132 } 133 default: 134 verdict = NFT_BREAK; 135 goto out; 136 } 137 138 dev = dev_get_by_index_rcu(nft_net(pkt), oif); 139 if (dev == NULL) 140 return; 141 142 skb->dev = dev; 143 skb->tstamp = 0; 144 neigh_xmit(neigh_table, dev, addr, skb); 145 out: 146 regs->verdict.code = verdict; 147 } 148 149 static int nft_fwd_neigh_init(const struct nft_ctx *ctx, 150 const struct nft_expr *expr, 151 const struct nlattr * const tb[]) 152 { 153 struct nft_fwd_neigh *priv = nft_expr_priv(expr); 154 unsigned int addr_len; 155 int err; 156 157 if (!tb[NFTA_FWD_SREG_DEV] || 158 !tb[NFTA_FWD_SREG_ADDR] || 159 !tb[NFTA_FWD_NFPROTO]) 160 return -EINVAL; 161 162 priv->nfproto = ntohl(nla_get_be32(tb[NFTA_FWD_NFPROTO])); 163 164 switch (priv->nfproto) { 165 case NFPROTO_IPV4: 166 addr_len = sizeof(struct in_addr); 167 break; 168 case NFPROTO_IPV6: 169 addr_len = sizeof(struct in6_addr); 170 break; 171 default: 172 return -EOPNOTSUPP; 173 } 174 175 err = nft_parse_register_load(tb[NFTA_FWD_SREG_DEV], &priv->sreg_dev, 176 sizeof(int)); 177 if (err < 0) 178 return err; 179 180 return nft_parse_register_load(tb[NFTA_FWD_SREG_ADDR], &priv->sreg_addr, 181 addr_len); 182 } 183 184 static int nft_fwd_neigh_dump(struct sk_buff *skb, const struct nft_expr *expr) 185 { 186 struct nft_fwd_neigh *priv = nft_expr_priv(expr); 187 188 if (nft_dump_register(skb, NFTA_FWD_SREG_DEV, priv->sreg_dev) || 189 nft_dump_register(skb, NFTA_FWD_SREG_ADDR, priv->sreg_addr) || 190 nla_put_be32(skb, NFTA_FWD_NFPROTO, htonl(priv->nfproto))) 191 goto nla_put_failure; 192 193 return 0; 194 195 nla_put_failure: 196 return -1; 197 } 198 199 static int nft_fwd_validate(const struct nft_ctx *ctx, 200 const struct nft_expr *expr, 201 const struct nft_data **data) 202 { 203 return nft_chain_validate_hooks(ctx->chain, (1 << NF_NETDEV_INGRESS) | 204 (1 << NF_NETDEV_EGRESS)); 205 } 206 207 static struct nft_expr_type nft_fwd_netdev_type; 208 static const struct nft_expr_ops nft_fwd_neigh_netdev_ops = { 209 .type = &nft_fwd_netdev_type, 210 .size = NFT_EXPR_SIZE(sizeof(struct nft_fwd_neigh)), 211 .eval = nft_fwd_neigh_eval, 212 .init = nft_fwd_neigh_init, 213 .dump = nft_fwd_neigh_dump, 214 .validate = nft_fwd_validate, 215 }; 216 217 static const struct nft_expr_ops nft_fwd_netdev_ops = { 218 .type = &nft_fwd_netdev_type, 219 .size = NFT_EXPR_SIZE(sizeof(struct nft_fwd_netdev)), 220 .eval = nft_fwd_netdev_eval, 221 .init = nft_fwd_netdev_init, 222 .dump = nft_fwd_netdev_dump, 223 .validate = nft_fwd_validate, 224 .offload = nft_fwd_netdev_offload, 225 }; 226 227 static const struct nft_expr_ops * 228 nft_fwd_select_ops(const struct nft_ctx *ctx, 229 const struct nlattr * const tb[]) 230 { 231 if (tb[NFTA_FWD_SREG_ADDR]) 232 return &nft_fwd_neigh_netdev_ops; 233 if (tb[NFTA_FWD_SREG_DEV]) 234 return &nft_fwd_netdev_ops; 235 236 return ERR_PTR(-EOPNOTSUPP); 237 } 238 239 static struct nft_expr_type nft_fwd_netdev_type __read_mostly = { 240 .family = NFPROTO_NETDEV, 241 .name = "fwd", 242 .select_ops = nft_fwd_select_ops, 243 .policy = nft_fwd_netdev_policy, 244 .maxattr = NFTA_FWD_MAX, 245 .owner = THIS_MODULE, 246 }; 247 248 static int __init nft_fwd_netdev_module_init(void) 249 { 250 return nft_register_expr(&nft_fwd_netdev_type); 251 } 252 253 static void __exit nft_fwd_netdev_module_exit(void) 254 { 255 nft_unregister_expr(&nft_fwd_netdev_type); 256 } 257 258 module_init(nft_fwd_netdev_module_init); 259 module_exit(nft_fwd_netdev_module_exit); 260 261 MODULE_LICENSE("GPL"); 262 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>"); 263 MODULE_ALIAS_NFT_AF_EXPR(5, "fwd"); 264