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