1/* SPDX-License-Identifier: GPL-2.0 */
  2#include <linux/module.h>
  3#include <linux/netfilter/nf_tables.h>
  4#include <net/netfilter/nf_tables.h>
  5#include <net/netfilter/nf_tables_core.h>
  6#include <net/netfilter/nf_socket.h>
  7#include <net/inet_sock.h>
  8#include <net/tcp.h>
  9
 10struct nft_socket {
 11	enum nft_socket_keys		key:8;
 12	union {
 13		enum nft_registers	dreg:8;
 14	};
 15};
 16
 17static void nft_socket_eval(const struct nft_expr *expr,
 18			    struct nft_regs *regs,
 19			    const struct nft_pktinfo *pkt)
 20{
 21	const struct nft_socket *priv = nft_expr_priv(expr);
 22	struct sk_buff *skb = pkt->skb;
 23	struct sock *sk = skb->sk;
 24	u32 *dest = &regs->data[priv->dreg];
 25
 26	if (sk && !net_eq(nft_net(pkt), sock_net(sk)))
 27		sk = NULL;
 28
 29	if (!sk)
 30		switch(nft_pf(pkt)) {
 31		case NFPROTO_IPV4:
 32			sk = nf_sk_lookup_slow_v4(nft_net(pkt), skb, nft_in(pkt));
 33			break;
 34#if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
 35		case NFPROTO_IPV6:
 36			sk = nf_sk_lookup_slow_v6(nft_net(pkt), skb, nft_in(pkt));
 37			break;
 38#endif
 39		default:
 40			WARN_ON_ONCE(1);
 41			regs->verdict.code = NFT_BREAK;
 42			return;
 43		}
 44
 45	if (!sk) {
 46		regs->verdict.code = NFT_BREAK;
 47		return;
 48	}
 49
 50	switch(priv->key) {
 51	case NFT_SOCKET_TRANSPARENT:
 52		nft_reg_store8(dest, inet_sk_transparent(sk));
 53		break;
 54	case NFT_SOCKET_MARK:
 55		if (sk_fullsock(sk)) {
 56			*dest = sk->sk_mark;
 57		} else {
 58			regs->verdict.code = NFT_BREAK;
 59			return;
 60		}
 61		break;
 62	default:
 63		WARN_ON(1);
 64		regs->verdict.code = NFT_BREAK;
 65	}
 66
 67	if (sk != skb->sk)
 68		sock_gen_put(sk);
 69}
 70
 71static const struct nla_policy nft_socket_policy[NFTA_SOCKET_MAX + 1] = {
 72	[NFTA_SOCKET_KEY]		= { .type = NLA_U32 },
 73	[NFTA_SOCKET_DREG]		= { .type = NLA_U32 },
 74};
 75
 76static int nft_socket_init(const struct nft_ctx *ctx,
 77			   const struct nft_expr *expr,
 78			   const struct nlattr * const tb[])
 79{
 80	struct nft_socket *priv = nft_expr_priv(expr);
 81	unsigned int len;
 82
 83	if (!tb[NFTA_SOCKET_DREG] || !tb[NFTA_SOCKET_KEY])
 84		return -EINVAL;
 85
 86	switch(ctx->family) {
 87	case NFPROTO_IPV4:
 88#if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
 89	case NFPROTO_IPV6:
 90#endif
 91	case NFPROTO_INET:
 92		break;
 93	default:
 94		return -EOPNOTSUPP;
 95	}
 96
 97	priv->key = ntohl(nla_get_u32(tb[NFTA_SOCKET_KEY]));
 98	switch(priv->key) {
 99	case NFT_SOCKET_TRANSPARENT:
100		len = sizeof(u8);
101		break;
102	case NFT_SOCKET_MARK:
103		len = sizeof(u32);
104		break;
105	default:
106		return -EOPNOTSUPP;
107	}
108
109	priv->dreg = nft_parse_register(tb[NFTA_SOCKET_DREG]);
110	return nft_validate_register_store(ctx, priv->dreg, NULL,
111					   NFT_DATA_VALUE, len);
112}
113
114static int nft_socket_dump(struct sk_buff *skb,
115			   const struct nft_expr *expr)
116{
117	const struct nft_socket *priv = nft_expr_priv(expr);
118
119	if (nla_put_u32(skb, NFTA_SOCKET_KEY, htonl(priv->key)))
120		return -1;
121	if (nft_dump_register(skb, NFTA_SOCKET_DREG, priv->dreg))
122		return -1;
123	return 0;
124}
125
126static struct nft_expr_type nft_socket_type;
127static const struct nft_expr_ops nft_socket_ops = {
128	.type		= &nft_socket_type,
129	.size		= NFT_EXPR_SIZE(sizeof(struct nft_socket)),
130	.eval		= nft_socket_eval,
131	.init		= nft_socket_init,
132	.dump		= nft_socket_dump,
133};
134
135static struct nft_expr_type nft_socket_type __read_mostly = {
136	.name		= "socket",
137	.ops		= &nft_socket_ops,
138	.policy		= nft_socket_policy,
139	.maxattr	= NFTA_SOCKET_MAX,
140	.owner		= THIS_MODULE,
141};
142
143static int __init nft_socket_module_init(void)
144{
145	return nft_register_expr(&nft_socket_type);
146}
147
148static void __exit nft_socket_module_exit(void)
149{
150	nft_unregister_expr(&nft_socket_type);
151}
152
153module_init(nft_socket_module_init);
154module_exit(nft_socket_module_exit);
155
156MODULE_LICENSE("GPL");
157MODULE_AUTHOR("Máté Eckl");
158MODULE_DESCRIPTION("nf_tables socket match module");
159MODULE_ALIAS_NFT_EXPR("socket");