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 const struct net_device *found; 80 81 /* 82 * Do not set flowi4_oif, it restricts results (for example, asking 83 * for oif 3 will get RTN_UNICAST result even if the daddr exits 84 * on another interface. 85 * 86 * Search results for the desired outinterface instead. 87 */ 88 if (priv->flags & NFTA_FIB_F_OIF) 89 oif = nft_out(pkt); 90 else if (priv->flags & NFTA_FIB_F_IIF) 91 oif = nft_in(pkt); 92 else 93 oif = NULL; 94 95 if (nft_hook(pkt) == NF_INET_PRE_ROUTING && 96 nft_fib_is_loopback(pkt->skb, nft_in(pkt))) { 97 nft_fib_store_result(dest, priv, pkt, 98 nft_in(pkt)->ifindex); 99 return; 100 } 101 102 iph = skb_header_pointer(pkt->skb, noff, sizeof(_iph), &_iph); 103 if (!iph) { 104 regs->verdict.code = NFT_BREAK; 105 return; 106 } 107 108 if (ipv4_is_zeronet(iph->saddr)) { 109 if (ipv4_is_lbcast(iph->daddr) || 110 ipv4_is_local_multicast(iph->daddr)) { 111 nft_fib_store_result(dest, priv, pkt, 112 get_ifindex(pkt->skb->dev)); 113 return; 114 } 115 } 116 117 if (priv->flags & NFTA_FIB_F_MARK) 118 fl4.flowi4_mark = pkt->skb->mark; 119 120 fl4.flowi4_tos = iph->tos & DSCP_BITS; 121 122 if (priv->flags & NFTA_FIB_F_DADDR) { 123 fl4.daddr = iph->daddr; 124 fl4.saddr = get_saddr(iph->saddr); 125 } else { 126 fl4.daddr = iph->saddr; 127 fl4.saddr = get_saddr(iph->daddr); 128 } 129 130 *dest = 0; 131 132 if (fib_lookup(nft_net(pkt), &fl4, &res, FIB_LOOKUP_IGNORE_LINKSTATE)) 133 return; 134 135 switch (res.type) { 136 case RTN_UNICAST: 137 break; 138 case RTN_LOCAL: /* Should not see RTN_LOCAL here */ 139 return; 140 default: 141 break; 142 } 143 144 if (!oif) { 145 found = FIB_RES_DEV(res); 146 } else { 147 if (!fib_info_nh_uses_dev(res.fi, oif)) 148 return; 149 150 found = oif; 151 } 152 153 switch (priv->result) { 154 case NFT_FIB_RESULT_OIF: 155 *dest = found->ifindex; 156 break; 157 case NFT_FIB_RESULT_OIFNAME: 158 strncpy((char *)dest, found->name, IFNAMSIZ); 159 break; 160 default: 161 WARN_ON_ONCE(1); 162 break; 163 } 164 } 165 EXPORT_SYMBOL_GPL(nft_fib4_eval); 166 167 static struct nft_expr_type nft_fib4_type; 168 169 static const struct nft_expr_ops nft_fib4_type_ops = { 170 .type = &nft_fib4_type, 171 .size = NFT_EXPR_SIZE(sizeof(struct nft_fib)), 172 .eval = nft_fib4_eval_type, 173 .init = nft_fib_init, 174 .dump = nft_fib_dump, 175 .validate = nft_fib_validate, 176 }; 177 178 static const struct nft_expr_ops nft_fib4_ops = { 179 .type = &nft_fib4_type, 180 .size = NFT_EXPR_SIZE(sizeof(struct nft_fib)), 181 .eval = nft_fib4_eval, 182 .init = nft_fib_init, 183 .dump = nft_fib_dump, 184 .validate = nft_fib_validate, 185 }; 186 187 static const struct nft_expr_ops * 188 nft_fib4_select_ops(const struct nft_ctx *ctx, 189 const struct nlattr * const tb[]) 190 { 191 enum nft_fib_result result; 192 193 if (!tb[NFTA_FIB_RESULT]) 194 return ERR_PTR(-EINVAL); 195 196 result = ntohl(nla_get_be32(tb[NFTA_FIB_RESULT])); 197 198 switch (result) { 199 case NFT_FIB_RESULT_OIF: 200 return &nft_fib4_ops; 201 case NFT_FIB_RESULT_OIFNAME: 202 return &nft_fib4_ops; 203 case NFT_FIB_RESULT_ADDRTYPE: 204 return &nft_fib4_type_ops; 205 default: 206 return ERR_PTR(-EOPNOTSUPP); 207 } 208 } 209 210 static struct nft_expr_type nft_fib4_type __read_mostly = { 211 .name = "fib", 212 .select_ops = nft_fib4_select_ops, 213 .policy = nft_fib_policy, 214 .maxattr = NFTA_FIB_MAX, 215 .family = NFPROTO_IPV4, 216 .owner = THIS_MODULE, 217 }; 218 219 static int __init nft_fib4_module_init(void) 220 { 221 return nft_register_expr(&nft_fib4_type); 222 } 223 224 static void __exit nft_fib4_module_exit(void) 225 { 226 nft_unregister_expr(&nft_fib4_type); 227 } 228 229 module_init(nft_fib4_module_init); 230 module_exit(nft_fib4_module_exit); 231 MODULE_LICENSE("GPL"); 232 MODULE_AUTHOR("Florian Westphal <fw@strlen.de>"); 233 MODULE_ALIAS_NFT_AF_EXPR(2, "fib"); 234