1 // SPDX-License-Identifier: GPL-2.0-only 2 3 #include <linux/kernel.h> 4 #include <linux/init.h> 5 #include <linux/module.h> 6 #include <linux/netlink.h> 7 #include <linux/netfilter.h> 8 #include <linux/netfilter/nf_tables.h> 9 #include <net/netfilter/nf_tables_core.h> 10 #include <net/netfilter/nf_tables.h> 11 #include <net/netfilter/nft_fib.h> 12 13 #include <net/ip_fib.h> 14 #include <net/route.h> 15 16 /* don't try to find route from mcast/bcast/zeronet */ 17 static __be32 get_saddr(__be32 addr) 18 { 19 if (ipv4_is_multicast(addr) || ipv4_is_lbcast(addr) || 20 ipv4_is_zeronet(addr)) 21 return 0; 22 return addr; 23 } 24 25 #define DSCP_BITS 0xfc 26 27 void nft_fib4_eval_type(const struct nft_expr *expr, struct nft_regs *regs, 28 const struct nft_pktinfo *pkt) 29 { 30 const struct nft_fib *priv = nft_expr_priv(expr); 31 int noff = skb_network_offset(pkt->skb); 32 u32 *dst = ®s->data[priv->dreg]; 33 const struct net_device *dev = NULL; 34 struct iphdr *iph, _iph; 35 __be32 addr; 36 37 if (priv->flags & NFTA_FIB_F_IIF) 38 dev = nft_in(pkt); 39 else if (priv->flags & NFTA_FIB_F_OIF) 40 dev = nft_out(pkt); 41 42 iph = skb_header_pointer(pkt->skb, noff, sizeof(_iph), &_iph); 43 if (!iph) { 44 regs->verdict.code = NFT_BREAK; 45 return; 46 } 47 48 if (priv->flags & NFTA_FIB_F_DADDR) 49 addr = iph->daddr; 50 else 51 addr = iph->saddr; 52 53 *dst = inet_dev_addr_type(nft_net(pkt), dev, addr); 54 } 55 EXPORT_SYMBOL_GPL(nft_fib4_eval_type); 56 57 void nft_fib4_eval(const struct nft_expr *expr, struct nft_regs *regs, 58 const struct nft_pktinfo *pkt) 59 { 60 const struct nft_fib *priv = nft_expr_priv(expr); 61 int noff = skb_network_offset(pkt->skb); 62 u32 *dest = ®s->data[priv->dreg]; 63 struct iphdr *iph, _iph; 64 struct fib_result res; 65 struct flowi4 fl4 = { 66 .flowi4_scope = RT_SCOPE_UNIVERSE, 67 .flowi4_iif = LOOPBACK_IFINDEX, 68 }; 69 const struct net_device *oif; 70 const struct net_device *found; 71 72 /* 73 * Do not set flowi4_oif, it restricts results (for example, asking 74 * for oif 3 will get RTN_UNICAST result even if the daddr exits 75 * on another interface. 76 * 77 * Search results for the desired outinterface instead. 78 */ 79 if (priv->flags & NFTA_FIB_F_OIF) 80 oif = nft_out(pkt); 81 else if (priv->flags & NFTA_FIB_F_IIF) 82 oif = nft_in(pkt); 83 else 84 oif = NULL; 85 86 if (priv->flags & NFTA_FIB_F_IIF) 87 fl4.flowi4_oif = l3mdev_master_ifindex_rcu(oif); 88 89 if (nft_hook(pkt) == NF_INET_PRE_ROUTING && 90 nft_fib_is_loopback(pkt->skb, nft_in(pkt))) { 91 nft_fib_store_result(dest, priv, nft_in(pkt)); 92 return; 93 } 94 95 iph = skb_header_pointer(pkt->skb, noff, sizeof(_iph), &_iph); 96 if (!iph) { 97 regs->verdict.code = NFT_BREAK; 98 return; 99 } 100 101 if (ipv4_is_zeronet(iph->saddr)) { 102 if (ipv4_is_lbcast(iph->daddr) || 103 ipv4_is_local_multicast(iph->daddr)) { 104 nft_fib_store_result(dest, priv, pkt->skb->dev); 105 return; 106 } 107 } 108 109 if (priv->flags & NFTA_FIB_F_MARK) 110 fl4.flowi4_mark = pkt->skb->mark; 111 112 fl4.flowi4_tos = iph->tos & DSCP_BITS; 113 114 if (priv->flags & NFTA_FIB_F_DADDR) { 115 fl4.daddr = iph->daddr; 116 fl4.saddr = get_saddr(iph->saddr); 117 } else { 118 fl4.daddr = iph->saddr; 119 fl4.saddr = get_saddr(iph->daddr); 120 } 121 122 *dest = 0; 123 124 if (fib_lookup(nft_net(pkt), &fl4, &res, FIB_LOOKUP_IGNORE_LINKSTATE)) 125 return; 126 127 switch (res.type) { 128 case RTN_UNICAST: 129 break; 130 case RTN_LOCAL: /* Should not see RTN_LOCAL here */ 131 return; 132 default: 133 break; 134 } 135 136 if (!oif) { 137 found = FIB_RES_DEV(res); 138 } else { 139 if (!fib_info_nh_uses_dev(res.fi, oif)) 140 return; 141 142 found = oif; 143 } 144 145 nft_fib_store_result(dest, priv, found); 146 } 147 EXPORT_SYMBOL_GPL(nft_fib4_eval); 148 149 static struct nft_expr_type nft_fib4_type; 150 151 static const struct nft_expr_ops nft_fib4_type_ops = { 152 .type = &nft_fib4_type, 153 .size = NFT_EXPR_SIZE(sizeof(struct nft_fib)), 154 .eval = nft_fib4_eval_type, 155 .init = nft_fib_init, 156 .dump = nft_fib_dump, 157 .validate = nft_fib_validate, 158 }; 159 160 static const struct nft_expr_ops nft_fib4_ops = { 161 .type = &nft_fib4_type, 162 .size = NFT_EXPR_SIZE(sizeof(struct nft_fib)), 163 .eval = nft_fib4_eval, 164 .init = nft_fib_init, 165 .dump = nft_fib_dump, 166 .validate = nft_fib_validate, 167 }; 168 169 static const struct nft_expr_ops * 170 nft_fib4_select_ops(const struct nft_ctx *ctx, 171 const struct nlattr * const tb[]) 172 { 173 enum nft_fib_result result; 174 175 if (!tb[NFTA_FIB_RESULT]) 176 return ERR_PTR(-EINVAL); 177 178 result = ntohl(nla_get_be32(tb[NFTA_FIB_RESULT])); 179 180 switch (result) { 181 case NFT_FIB_RESULT_OIF: 182 return &nft_fib4_ops; 183 case NFT_FIB_RESULT_OIFNAME: 184 return &nft_fib4_ops; 185 case NFT_FIB_RESULT_ADDRTYPE: 186 return &nft_fib4_type_ops; 187 default: 188 return ERR_PTR(-EOPNOTSUPP); 189 } 190 } 191 192 static struct nft_expr_type nft_fib4_type __read_mostly = { 193 .name = "fib", 194 .select_ops = nft_fib4_select_ops, 195 .policy = nft_fib_policy, 196 .maxattr = NFTA_FIB_MAX, 197 .family = NFPROTO_IPV4, 198 .owner = THIS_MODULE, 199 }; 200 201 static int __init nft_fib4_module_init(void) 202 { 203 return nft_register_expr(&nft_fib4_type); 204 } 205 206 static void __exit nft_fib4_module_exit(void) 207 { 208 nft_unregister_expr(&nft_fib4_type); 209 } 210 211 module_init(nft_fib4_module_init); 212 module_exit(nft_fib4_module_exit); 213 MODULE_LICENSE("GPL"); 214 MODULE_AUTHOR("Florian Westphal <fw@strlen.de>"); 215 MODULE_ALIAS_NFT_AF_EXPR(2, "fib"); 216 MODULE_DESCRIPTION("nftables fib / ip route lookup support"); 217