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, 60 const struct nft_expr *expr, bool reset) 61 { 62 struct nft_fwd_netdev *priv = nft_expr_priv(expr); 63 64 if (nft_dump_register(skb, NFTA_FWD_SREG_DEV, priv->sreg_dev)) 65 goto nla_put_failure; 66 67 return 0; 68 69 nla_put_failure: 70 return -1; 71 } 72 73 static int nft_fwd_netdev_offload(struct nft_offload_ctx *ctx, 74 struct nft_flow_rule *flow, 75 const struct nft_expr *expr) 76 { 77 const struct nft_fwd_netdev *priv = nft_expr_priv(expr); 78 int oif = ctx->regs[priv->sreg_dev].data.data[0]; 79 80 return nft_fwd_dup_netdev_offload(ctx, flow, FLOW_ACTION_REDIRECT, oif); 81 } 82 83 static bool nft_fwd_netdev_offload_action(const struct nft_expr *expr) 84 { 85 return true; 86 } 87 88 struct nft_fwd_neigh { 89 u8 sreg_dev; 90 u8 sreg_addr; 91 u8 nfproto; 92 }; 93 94 static void nft_fwd_neigh_eval(const struct nft_expr *expr, 95 struct nft_regs *regs, 96 const struct nft_pktinfo *pkt) 97 { 98 struct nft_fwd_neigh *priv = nft_expr_priv(expr); 99 void *addr = ®s->data[priv->sreg_addr]; 100 int oif = regs->data[priv->sreg_dev]; 101 unsigned int verdict = NF_STOLEN; 102 struct sk_buff *skb = pkt->skb; 103 struct net_device *dev; 104 int neigh_table; 105 106 switch (priv->nfproto) { 107 case NFPROTO_IPV4: { 108 struct iphdr *iph; 109 110 if (skb->protocol != htons(ETH_P_IP)) { 111 verdict = NFT_BREAK; 112 goto out; 113 } 114 if (skb_try_make_writable(skb, sizeof(*iph))) { 115 verdict = NF_DROP; 116 goto out; 117 } 118 iph = ip_hdr(skb); 119 ip_decrease_ttl(iph); 120 neigh_table = NEIGH_ARP_TABLE; 121 break; 122 } 123 case NFPROTO_IPV6: { 124 struct ipv6hdr *ip6h; 125 126 if (skb->protocol != htons(ETH_P_IPV6)) { 127 verdict = NFT_BREAK; 128 goto out; 129 } 130 if (skb_try_make_writable(skb, sizeof(*ip6h))) { 131 verdict = NF_DROP; 132 goto out; 133 } 134 ip6h = ipv6_hdr(skb); 135 ip6h->hop_limit--; 136 neigh_table = NEIGH_ND_TABLE; 137 break; 138 } 139 default: 140 verdict = NFT_BREAK; 141 goto out; 142 } 143 144 dev = dev_get_by_index_rcu(nft_net(pkt), oif); 145 if (dev == NULL) 146 return; 147 148 skb->dev = dev; 149 skb_clear_tstamp(skb); 150 neigh_xmit(neigh_table, dev, addr, skb); 151 out: 152 regs->verdict.code = verdict; 153 } 154 155 static int nft_fwd_neigh_init(const struct nft_ctx *ctx, 156 const struct nft_expr *expr, 157 const struct nlattr * const tb[]) 158 { 159 struct nft_fwd_neigh *priv = nft_expr_priv(expr); 160 unsigned int addr_len; 161 int err; 162 163 if (!tb[NFTA_FWD_SREG_DEV] || 164 !tb[NFTA_FWD_SREG_ADDR] || 165 !tb[NFTA_FWD_NFPROTO]) 166 return -EINVAL; 167 168 priv->nfproto = ntohl(nla_get_be32(tb[NFTA_FWD_NFPROTO])); 169 170 switch (priv->nfproto) { 171 case NFPROTO_IPV4: 172 addr_len = sizeof(struct in_addr); 173 break; 174 case NFPROTO_IPV6: 175 addr_len = sizeof(struct in6_addr); 176 break; 177 default: 178 return -EOPNOTSUPP; 179 } 180 181 err = nft_parse_register_load(tb[NFTA_FWD_SREG_DEV], &priv->sreg_dev, 182 sizeof(int)); 183 if (err < 0) 184 return err; 185 186 return nft_parse_register_load(tb[NFTA_FWD_SREG_ADDR], &priv->sreg_addr, 187 addr_len); 188 } 189 190 static int nft_fwd_neigh_dump(struct sk_buff *skb, 191 const struct nft_expr *expr, bool reset) 192 { 193 struct nft_fwd_neigh *priv = nft_expr_priv(expr); 194 195 if (nft_dump_register(skb, NFTA_FWD_SREG_DEV, priv->sreg_dev) || 196 nft_dump_register(skb, NFTA_FWD_SREG_ADDR, priv->sreg_addr) || 197 nla_put_be32(skb, NFTA_FWD_NFPROTO, htonl(priv->nfproto))) 198 goto nla_put_failure; 199 200 return 0; 201 202 nla_put_failure: 203 return -1; 204 } 205 206 static int nft_fwd_validate(const struct nft_ctx *ctx, 207 const struct nft_expr *expr, 208 const struct nft_data **data) 209 { 210 return nft_chain_validate_hooks(ctx->chain, (1 << NF_NETDEV_INGRESS) | 211 (1 << NF_NETDEV_EGRESS)); 212 } 213 214 static struct nft_expr_type nft_fwd_netdev_type; 215 static const struct nft_expr_ops nft_fwd_neigh_netdev_ops = { 216 .type = &nft_fwd_netdev_type, 217 .size = NFT_EXPR_SIZE(sizeof(struct nft_fwd_neigh)), 218 .eval = nft_fwd_neigh_eval, 219 .init = nft_fwd_neigh_init, 220 .dump = nft_fwd_neigh_dump, 221 .validate = nft_fwd_validate, 222 .reduce = NFT_REDUCE_READONLY, 223 }; 224 225 static const struct nft_expr_ops nft_fwd_netdev_ops = { 226 .type = &nft_fwd_netdev_type, 227 .size = NFT_EXPR_SIZE(sizeof(struct nft_fwd_netdev)), 228 .eval = nft_fwd_netdev_eval, 229 .init = nft_fwd_netdev_init, 230 .dump = nft_fwd_netdev_dump, 231 .validate = nft_fwd_validate, 232 .reduce = NFT_REDUCE_READONLY, 233 .offload = nft_fwd_netdev_offload, 234 .offload_action = nft_fwd_netdev_offload_action, 235 }; 236 237 static const struct nft_expr_ops * 238 nft_fwd_select_ops(const struct nft_ctx *ctx, 239 const struct nlattr * const tb[]) 240 { 241 if (tb[NFTA_FWD_SREG_ADDR]) 242 return &nft_fwd_neigh_netdev_ops; 243 if (tb[NFTA_FWD_SREG_DEV]) 244 return &nft_fwd_netdev_ops; 245 246 return ERR_PTR(-EOPNOTSUPP); 247 } 248 249 static struct nft_expr_type nft_fwd_netdev_type __read_mostly = { 250 .family = NFPROTO_NETDEV, 251 .name = "fwd", 252 .select_ops = nft_fwd_select_ops, 253 .policy = nft_fwd_netdev_policy, 254 .maxattr = NFTA_FWD_MAX, 255 .owner = THIS_MODULE, 256 }; 257 258 static int __init nft_fwd_netdev_module_init(void) 259 { 260 return nft_register_expr(&nft_fwd_netdev_type); 261 } 262 263 static void __exit nft_fwd_netdev_module_exit(void) 264 { 265 nft_unregister_expr(&nft_fwd_netdev_type); 266 } 267 268 module_init(nft_fwd_netdev_module_init); 269 module_exit(nft_fwd_netdev_module_exit); 270 271 MODULE_LICENSE("GPL"); 272 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>"); 273 MODULE_ALIAS_NFT_AF_EXPR(5, "fwd"); 274