nft_fib_ipv4.c

  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/flow.h>
 14#include <net/ip.h>
 15#include <net/ip_fib.h>
 16#include <net/route.h>
 17
 18/* don't try to find route from mcast/bcast/zeronet */
 19static __be32 get_saddr(__be32 addr)
 20{
 21	if (ipv4_is_multicast(addr) || ipv4_is_lbcast(addr) ||
 22	    ipv4_is_zeronet(addr))
 23		return 0;
 24	return addr;
 25}
 26
 27void 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 = &regs->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	if (priv->flags & (NFTA_FIB_F_IIF | NFTA_FIB_F_OIF)) {
 54		*dst = inet_dev_addr_type(nft_net(pkt), dev, addr);
 55		return;
 56	}
 57
 58	*dst = inet_addr_type_dev_table(nft_net(pkt), pkt->skb->dev, addr);
 59}
 60EXPORT_SYMBOL_GPL(nft_fib4_eval_type);
 61
 62void nft_fib4_eval(const struct nft_expr *expr, struct nft_regs *regs,
 63		   const struct nft_pktinfo *pkt)
 64{
 65	const struct nft_fib *priv = nft_expr_priv(expr);
 66	int noff = skb_network_offset(pkt->skb);
 67	u32 *dest = &regs->data[priv->dreg];
 68	struct iphdr *iph, _iph;
 69	struct fib_result res;
 70	struct flowi4 fl4 = {
 71		.flowi4_scope = RT_SCOPE_UNIVERSE,
 72		.flowi4_iif = LOOPBACK_IFINDEX,
 73		.flowi4_proto = pkt->tprot,
 74		.flowi4_uid = sock_net_uid(nft_net(pkt), NULL),
 75	};
 76	const struct net_device *oif;
 77	const struct net_device *found;
 78
 79	if (nft_fib_can_skip(pkt)) {
 80		nft_fib_store_result(dest, priv, nft_in(pkt));
 81		return;
 82	}
 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	fl4.flowi4_l3mdev = nft_fib_l3mdev_master_ifindex_rcu(pkt, oif);
 99
100	iph = skb_header_pointer(pkt->skb, noff, sizeof(_iph), &_iph);
101	if (!iph) {
102		regs->verdict.code = NFT_BREAK;
103		return;
104	}
105
106	if (ipv4_is_zeronet(iph->saddr)) {
107		if (ipv4_is_lbcast(iph->daddr) ||
108		    ipv4_is_local_multicast(iph->daddr)) {
109			nft_fib_store_result(dest, priv, pkt->skb->dev);
110			return;
111		}
112	}
113
114	if (priv->flags & NFTA_FIB_F_MARK)
115		fl4.flowi4_mark = pkt->skb->mark;
116
117	fl4.flowi4_dscp = ip4h_dscp(iph);
118
119	if (priv->flags & NFTA_FIB_F_DADDR) {
120		fl4.daddr = iph->daddr;
121		fl4.saddr = get_saddr(iph->saddr);
122	} else {
123		if (nft_hook(pkt) == NF_INET_FORWARD &&
124		    priv->flags & NFTA_FIB_F_IIF)
125			fl4.flowi4_iif = nft_out(pkt)->ifindex;
126
127		fl4.daddr = iph->saddr;
128		fl4.saddr = get_saddr(iph->daddr);
129	}
130
131	*dest = 0;
132
133	if (fib_lookup(nft_net(pkt), &fl4, &res, FIB_LOOKUP_IGNORE_LINKSTATE))
134		return;
135
136	switch (res.type) {
137	case RTN_UNICAST:
138		break;
139	case RTN_LOCAL: /* Should not see RTN_LOCAL here */
140		return;
141	default:
142		break;
143	}
144
145	if (!oif) {
146		found = FIB_RES_DEV(res);
147	} else {
148		if (!fib_info_nh_uses_dev(res.fi, oif))
149			return;
150		found = oif;
151	}
152
153	nft_fib_store_result(dest, priv, found);
154}
155EXPORT_SYMBOL_GPL(nft_fib4_eval);
156
157static struct nft_expr_type nft_fib4_type;
158
159static const struct nft_expr_ops nft_fib4_type_ops = {
160	.type		= &nft_fib4_type,
161	.size		= NFT_EXPR_SIZE(sizeof(struct nft_fib)),
162	.eval		= nft_fib4_eval_type,
163	.init		= nft_fib_init,
164	.dump		= nft_fib_dump,
165	.validate	= nft_fib_validate,
166	.reduce		= nft_fib_reduce,
167};
168
169static const struct nft_expr_ops nft_fib4_ops = {
170	.type		= &nft_fib4_type,
171	.size		= NFT_EXPR_SIZE(sizeof(struct nft_fib)),
172	.eval		= nft_fib4_eval,
173	.init		= nft_fib_init,
174	.dump		= nft_fib_dump,
175	.validate	= nft_fib_validate,
176	.reduce		= nft_fib_reduce,
177};
178
179static const struct nft_expr_ops *
180nft_fib4_select_ops(const struct nft_ctx *ctx,
181		    const struct nlattr * const tb[])
182{
183	enum nft_fib_result result;
184
185	if (!tb[NFTA_FIB_RESULT])
186		return ERR_PTR(-EINVAL);
187
188	result = ntohl(nla_get_be32(tb[NFTA_FIB_RESULT]));
189
190	switch (result) {
191	case NFT_FIB_RESULT_OIF:
192		return &nft_fib4_ops;
193	case NFT_FIB_RESULT_OIFNAME:
194		return &nft_fib4_ops;
195	case NFT_FIB_RESULT_ADDRTYPE:
196		return &nft_fib4_type_ops;
197	default:
198		return ERR_PTR(-EOPNOTSUPP);
199	}
200}
201
202static struct nft_expr_type nft_fib4_type __read_mostly = {
203	.name		= "fib",
204	.select_ops	= nft_fib4_select_ops,
205	.policy		= nft_fib_policy,
206	.maxattr	= NFTA_FIB_MAX,
207	.family		= NFPROTO_IPV4,
208	.owner		= THIS_MODULE,
209};
210
211static int __init nft_fib4_module_init(void)
212{
213	return nft_register_expr(&nft_fib4_type);
214}
215
216static void __exit nft_fib4_module_exit(void)
217{
218	nft_unregister_expr(&nft_fib4_type);
219}
220
221module_init(nft_fib4_module_init);
222module_exit(nft_fib4_module_exit);
223MODULE_LICENSE("GPL");
224MODULE_AUTHOR("Florian Westphal <fw@strlen.de>");
225MODULE_ALIAS_NFT_AF_EXPR(2, "fib");
226MODULE_DESCRIPTION("nftables fib / ip route lookup support");