1 /* 2 * This program is free software; you can redistribute it and/or modify 3 * it under the terms of the GNU General Public License version 2 as 4 * published by the Free Software Foundation. 5 */ 6 7 #include <linux/kernel.h> 8 #include <linux/init.h> 9 #include <linux/module.h> 10 #include <linux/netlink.h> 11 #include <linux/netfilter.h> 12 #include <linux/netfilter/nf_tables.h> 13 #include <net/netfilter/nf_tables_core.h> 14 #include <net/netfilter/nf_tables.h> 15 #include <net/netfilter/nft_fib.h> 16 17 #include <net/ip_fib.h> 18 #include <net/route.h> 19 20 /* don't try to find route from mcast/bcast/zeronet */ 21 static __be32 get_saddr(__be32 addr) 22 { 23 if (ipv4_is_multicast(addr) || ipv4_is_lbcast(addr) || 24 ipv4_is_zeronet(addr)) 25 return 0; 26 return addr; 27 } 28 29 #define DSCP_BITS 0xfc 30 31 void nft_fib4_eval_type(const struct nft_expr *expr, struct nft_regs *regs, 32 const struct nft_pktinfo *pkt) 33 { 34 const struct nft_fib *priv = nft_expr_priv(expr); 35 int noff = skb_network_offset(pkt->skb); 36 u32 *dst = ®s->data[priv->dreg]; 37 const struct net_device *dev = NULL; 38 struct iphdr *iph, _iph; 39 __be32 addr; 40 41 if (priv->flags & NFTA_FIB_F_IIF) 42 dev = nft_in(pkt); 43 else if (priv->flags & NFTA_FIB_F_OIF) 44 dev = nft_out(pkt); 45 46 iph = skb_header_pointer(pkt->skb, noff, sizeof(_iph), &_iph); 47 if (!iph) { 48 regs->verdict.code = NFT_BREAK; 49 return; 50 } 51 52 if (priv->flags & NFTA_FIB_F_DADDR) 53 addr = iph->daddr; 54 else 55 addr = iph->saddr; 56 57 *dst = inet_dev_addr_type(nft_net(pkt), dev, addr); 58 } 59 EXPORT_SYMBOL_GPL(nft_fib4_eval_type); 60 61 static int get_ifindex(const struct net_device *dev) 62 { 63 return dev ? dev->ifindex : 0; 64 } 65 66 void nft_fib4_eval(const struct nft_expr *expr, struct nft_regs *regs, 67 const struct nft_pktinfo *pkt) 68 { 69 const struct nft_fib *priv = nft_expr_priv(expr); 70 int noff = skb_network_offset(pkt->skb); 71 u32 *dest = ®s->data[priv->dreg]; 72 struct iphdr *iph, _iph; 73 struct fib_result res; 74 struct flowi4 fl4 = { 75 .flowi4_scope = RT_SCOPE_UNIVERSE, 76 .flowi4_iif = LOOPBACK_IFINDEX, 77 }; 78 const struct net_device *oif; 79 struct net_device *found; 80 #ifdef CONFIG_IP_ROUTE_MULTIPATH 81 int i; 82 #endif 83 84 /* 85 * Do not set flowi4_oif, it restricts results (for example, asking 86 * for oif 3 will get RTN_UNICAST result even if the daddr exits 87 * on another interface. 88 * 89 * Search results for the desired outinterface instead. 90 */ 91 if (priv->flags & NFTA_FIB_F_OIF) 92 oif = nft_out(pkt); 93 else if (priv->flags & NFTA_FIB_F_IIF) 94 oif = nft_in(pkt); 95 else 96 oif = NULL; 97 98 if (nft_hook(pkt) == NF_INET_PRE_ROUTING && 99 nft_fib_is_loopback(pkt->skb, nft_in(pkt))) { 100 nft_fib_store_result(dest, priv, pkt, 101 nft_in(pkt)->ifindex); 102 return; 103 } 104 105 iph = skb_header_pointer(pkt->skb, noff, sizeof(_iph), &_iph); 106 if (!iph) { 107 regs->verdict.code = NFT_BREAK; 108 return; 109 } 110 111 if (ipv4_is_zeronet(iph->saddr)) { 112 if (ipv4_is_lbcast(iph->daddr) || 113 ipv4_is_local_multicast(iph->daddr)) { 114 nft_fib_store_result(dest, priv, pkt, 115 get_ifindex(pkt->skb->dev)); 116 return; 117 } 118 } 119 120 if (priv->flags & NFTA_FIB_F_MARK) 121 fl4.flowi4_mark = pkt->skb->mark; 122 123 fl4.flowi4_tos = iph->tos & DSCP_BITS; 124 125 if (priv->flags & NFTA_FIB_F_DADDR) { 126 fl4.daddr = iph->daddr; 127 fl4.saddr = get_saddr(iph->saddr); 128 } else { 129 fl4.daddr = iph->saddr; 130 fl4.saddr = get_saddr(iph->daddr); 131 } 132 133 *dest = 0; 134 135 if (fib_lookup(nft_net(pkt), &fl4, &res, FIB_LOOKUP_IGNORE_LINKSTATE)) 136 return; 137 138 switch (res.type) { 139 case RTN_UNICAST: 140 break; 141 case RTN_LOCAL: /* Should not see RTN_LOCAL here */ 142 return; 143 default: 144 break; 145 } 146 147 if (!oif) { 148 found = FIB_RES_DEV(res); 149 goto ok; 150 } 151 152 #ifdef CONFIG_IP_ROUTE_MULTIPATH 153 for (i = 0; i < res.fi->fib_nhs; i++) { 154 struct fib_nh *nh = &res.fi->fib_nh[i]; 155 156 if (nh->nh_dev == oif) { 157 found = nh->nh_dev; 158 goto ok; 159 } 160 } 161 return; 162 #else 163 found = FIB_RES_DEV(res); 164 if (found != oif) 165 return; 166 #endif 167 ok: 168 switch (priv->result) { 169 case NFT_FIB_RESULT_OIF: 170 *dest = found->ifindex; 171 break; 172 case NFT_FIB_RESULT_OIFNAME: 173 strncpy((char *)dest, found->name, IFNAMSIZ); 174 break; 175 default: 176 WARN_ON_ONCE(1); 177 break; 178 } 179 } 180 EXPORT_SYMBOL_GPL(nft_fib4_eval); 181 182 static struct nft_expr_type nft_fib4_type; 183 184 static const struct nft_expr_ops nft_fib4_type_ops = { 185 .type = &nft_fib4_type, 186 .size = NFT_EXPR_SIZE(sizeof(struct nft_fib)), 187 .eval = nft_fib4_eval_type, 188 .init = nft_fib_init, 189 .dump = nft_fib_dump, 190 .validate = nft_fib_validate, 191 }; 192 193 static const struct nft_expr_ops nft_fib4_ops = { 194 .type = &nft_fib4_type, 195 .size = NFT_EXPR_SIZE(sizeof(struct nft_fib)), 196 .eval = nft_fib4_eval, 197 .init = nft_fib_init, 198 .dump = nft_fib_dump, 199 .validate = nft_fib_validate, 200 }; 201 202 static const struct nft_expr_ops * 203 nft_fib4_select_ops(const struct nft_ctx *ctx, 204 const struct nlattr * const tb[]) 205 { 206 enum nft_fib_result result; 207 208 if (!tb[NFTA_FIB_RESULT]) 209 return ERR_PTR(-EINVAL); 210 211 result = ntohl(nla_get_be32(tb[NFTA_FIB_RESULT])); 212 213 switch (result) { 214 case NFT_FIB_RESULT_OIF: 215 return &nft_fib4_ops; 216 case NFT_FIB_RESULT_OIFNAME: 217 return &nft_fib4_ops; 218 case NFT_FIB_RESULT_ADDRTYPE: 219 return &nft_fib4_type_ops; 220 default: 221 return ERR_PTR(-EOPNOTSUPP); 222 } 223 } 224 225 static struct nft_expr_type nft_fib4_type __read_mostly = { 226 .name = "fib", 227 .select_ops = nft_fib4_select_ops, 228 .policy = nft_fib_policy, 229 .maxattr = NFTA_FIB_MAX, 230 .family = NFPROTO_IPV4, 231 .owner = THIS_MODULE, 232 }; 233 234 static int __init nft_fib4_module_init(void) 235 { 236 return nft_register_expr(&nft_fib4_type); 237 } 238 239 static void __exit nft_fib4_module_exit(void) 240 { 241 nft_unregister_expr(&nft_fib4_type); 242 } 243 244 module_init(nft_fib4_module_init); 245 module_exit(nft_fib4_module_exit); 246 MODULE_LICENSE("GPL"); 247 MODULE_AUTHOR("Florian Westphal <fw@strlen.de>"); 248 MODULE_ALIAS_NFT_AF_EXPR(2, "fib"); 249