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 .flowi4_uid = sock_net_uid(nft_net(pkt), NULL), 69 }; 70 const struct net_device *oif; 71 const struct net_device *found; 72 73 /* 74 * Do not set flowi4_oif, it restricts results (for example, asking 75 * for oif 3 will get RTN_UNICAST result even if the daddr exits 76 * on another interface. 77 * 78 * Search results for the desired outinterface instead. 79 */ 80 if (priv->flags & NFTA_FIB_F_OIF) 81 oif = nft_out(pkt); 82 else if (priv->flags & NFTA_FIB_F_IIF) 83 oif = nft_in(pkt); 84 else 85 oif = NULL; 86 87 if (priv->flags & NFTA_FIB_F_IIF) 88 fl4.flowi4_l3mdev = l3mdev_master_ifindex_rcu(oif); 89 90 if (nft_hook(pkt) == NF_INET_PRE_ROUTING && 91 nft_fib_is_loopback(pkt->skb, nft_in(pkt))) { 92 nft_fib_store_result(dest, priv, nft_in(pkt)); 93 return; 94 } 95 96 iph = skb_header_pointer(pkt->skb, noff, sizeof(_iph), &_iph); 97 if (!iph) { 98 regs->verdict.code = NFT_BREAK; 99 return; 100 } 101 102 if (ipv4_is_zeronet(iph->saddr)) { 103 if (ipv4_is_lbcast(iph->daddr) || 104 ipv4_is_local_multicast(iph->daddr)) { 105 nft_fib_store_result(dest, priv, pkt->skb->dev); 106 return; 107 } 108 } 109 110 if (priv->flags & NFTA_FIB_F_MARK) 111 fl4.flowi4_mark = pkt->skb->mark; 112 113 fl4.flowi4_tos = iph->tos & DSCP_BITS; 114 115 if (priv->flags & NFTA_FIB_F_DADDR) { 116 fl4.daddr = iph->daddr; 117 fl4.saddr = get_saddr(iph->saddr); 118 } else { 119 if (nft_hook(pkt) == NF_INET_FORWARD && 120 priv->flags & NFTA_FIB_F_IIF) 121 fl4.flowi4_iif = nft_out(pkt)->ifindex; 122 123 fl4.daddr = iph->saddr; 124 fl4.saddr = get_saddr(iph->daddr); 125 } 126 127 *dest = 0; 128 129 if (fib_lookup(nft_net(pkt), &fl4, &res, FIB_LOOKUP_IGNORE_LINKSTATE)) 130 return; 131 132 switch (res.type) { 133 case RTN_UNICAST: 134 break; 135 case RTN_LOCAL: /* Should not see RTN_LOCAL here */ 136 return; 137 default: 138 break; 139 } 140 141 if (!oif) { 142 found = FIB_RES_DEV(res); 143 } else { 144 if (!fib_info_nh_uses_dev(res.fi, oif)) 145 return; 146 147 found = oif; 148 } 149 150 nft_fib_store_result(dest, priv, found); 151 } 152 EXPORT_SYMBOL_GPL(nft_fib4_eval); 153 154 static struct nft_expr_type nft_fib4_type; 155 156 static const struct nft_expr_ops nft_fib4_type_ops = { 157 .type = &nft_fib4_type, 158 .size = NFT_EXPR_SIZE(sizeof(struct nft_fib)), 159 .eval = nft_fib4_eval_type, 160 .init = nft_fib_init, 161 .dump = nft_fib_dump, 162 .validate = nft_fib_validate, 163 .reduce = nft_fib_reduce, 164 }; 165 166 static const struct nft_expr_ops nft_fib4_ops = { 167 .type = &nft_fib4_type, 168 .size = NFT_EXPR_SIZE(sizeof(struct nft_fib)), 169 .eval = nft_fib4_eval, 170 .init = nft_fib_init, 171 .dump = nft_fib_dump, 172 .validate = nft_fib_validate, 173 .reduce = nft_fib_reduce, 174 }; 175 176 static const struct nft_expr_ops * 177 nft_fib4_select_ops(const struct nft_ctx *ctx, 178 const struct nlattr * const tb[]) 179 { 180 enum nft_fib_result result; 181 182 if (!tb[NFTA_FIB_RESULT]) 183 return ERR_PTR(-EINVAL); 184 185 result = ntohl(nla_get_be32(tb[NFTA_FIB_RESULT])); 186 187 switch (result) { 188 case NFT_FIB_RESULT_OIF: 189 return &nft_fib4_ops; 190 case NFT_FIB_RESULT_OIFNAME: 191 return &nft_fib4_ops; 192 case NFT_FIB_RESULT_ADDRTYPE: 193 return &nft_fib4_type_ops; 194 default: 195 return ERR_PTR(-EOPNOTSUPP); 196 } 197 } 198 199 static struct nft_expr_type nft_fib4_type __read_mostly = { 200 .name = "fib", 201 .select_ops = nft_fib4_select_ops, 202 .policy = nft_fib_policy, 203 .maxattr = NFTA_FIB_MAX, 204 .family = NFPROTO_IPV4, 205 .owner = THIS_MODULE, 206 }; 207 208 static int __init nft_fib4_module_init(void) 209 { 210 return nft_register_expr(&nft_fib4_type); 211 } 212 213 static void __exit nft_fib4_module_exit(void) 214 { 215 nft_unregister_expr(&nft_fib4_type); 216 } 217 218 module_init(nft_fib4_module_init); 219 module_exit(nft_fib4_module_exit); 220 MODULE_LICENSE("GPL"); 221 MODULE_AUTHOR("Florian Westphal <fw@strlen.de>"); 222 MODULE_ALIAS_NFT_AF_EXPR(2, "fib"); 223 MODULE_DESCRIPTION("nftables fib / ip route lookup support"); 224