nft_socket.c
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/* SPDX-License-Identifier: GPL-2.0 */
#include <linux/module.h>
#include <linux/netfilter/nf_tables.h>
#include <net/netfilter/nf_tables.h>
#include <net/netfilter/nf_tables_core.h>
#include <net/netfilter/nf_socket.h>
#include <net/inet_sock.h>
#include <net/tcp.h>
struct nft_socket {
enum nft_socket_keys key:8;
union {
enum nft_registers dreg:8;
};
};
static void nft_socket_wildcard(const struct nft_pktinfo *pkt,
struct nft_regs *regs, struct sock *sk,
u32 *dest)
{
switch (nft_pf(pkt)) {
case NFPROTO_IPV4:
nft_reg_store8(dest, inet_sk(sk)->inet_rcv_saddr == 0);
break;
#if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
case NFPROTO_IPV6:
nft_reg_store8(dest, ipv6_addr_any(&sk->sk_v6_rcv_saddr));
break;
#endif
default:
regs->verdict.code = NFT_BREAK;
return;
}
}
static void nft_socket_eval(const struct nft_expr *expr,
struct nft_regs *regs,
const struct nft_pktinfo *pkt)
{
const struct nft_socket *priv = nft_expr_priv(expr);
struct sk_buff *skb = pkt->skb;
struct sock *sk = skb->sk;
u32 *dest = ®s->data[priv->dreg];
if (sk && !net_eq(nft_net(pkt), sock_net(sk)))
sk = NULL;
if (!sk)
switch(nft_pf(pkt)) {
case NFPROTO_IPV4:
sk = nf_sk_lookup_slow_v4(nft_net(pkt), skb, nft_in(pkt));
break;
#if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
case NFPROTO_IPV6:
sk = nf_sk_lookup_slow_v6(nft_net(pkt), skb, nft_in(pkt));
break;
#endif
default:
WARN_ON_ONCE(1);
regs->verdict.code = NFT_BREAK;
return;
}
if (!sk) {
regs->verdict.code = NFT_BREAK;
return;
}
switch(priv->key) {
case NFT_SOCKET_TRANSPARENT:
nft_reg_store8(dest, inet_sk_transparent(sk));
break;
case NFT_SOCKET_MARK:
if (sk_fullsock(sk)) {
*dest = sk->sk_mark;
} else {
regs->verdict.code = NFT_BREAK;
return;
}
break;
case NFT_SOCKET_WILDCARD:
if (!sk_fullsock(sk)) {
regs->verdict.code = NFT_BREAK;
return;
}
nft_socket_wildcard(pkt, regs, sk, dest);
break;
default:
WARN_ON(1);
regs->verdict.code = NFT_BREAK;
}
if (sk != skb->sk)
sock_gen_put(sk);
}
static const struct nla_policy nft_socket_policy[NFTA_SOCKET_MAX + 1] = {
[NFTA_SOCKET_KEY] = { .type = NLA_U32 },
[NFTA_SOCKET_DREG] = { .type = NLA_U32 },
};
static int nft_socket_init(const struct nft_ctx *ctx,
const struct nft_expr *expr,
const struct nlattr * const tb[])
{
struct nft_socket *priv = nft_expr_priv(expr);
unsigned int len;
if (!tb[NFTA_SOCKET_DREG] || !tb[NFTA_SOCKET_KEY])
return -EINVAL;
switch(ctx->family) {
case NFPROTO_IPV4:
#if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
case NFPROTO_IPV6:
#endif
case NFPROTO_INET:
break;
default:
return -EOPNOTSUPP;
}
priv->key = ntohl(nla_get_u32(tb[NFTA_SOCKET_KEY]));
switch(priv->key) {
case NFT_SOCKET_TRANSPARENT:
case NFT_SOCKET_WILDCARD:
len = sizeof(u8);
break;
case NFT_SOCKET_MARK:
len = sizeof(u32);
break;
default:
return -EOPNOTSUPP;
}
priv->dreg = nft_parse_register(tb[NFTA_SOCKET_DREG]);
return nft_validate_register_store(ctx, priv->dreg, NULL,
NFT_DATA_VALUE, len);
}
static int nft_socket_dump(struct sk_buff *skb,
const struct nft_expr *expr)
{
const struct nft_socket *priv = nft_expr_priv(expr);
if (nla_put_u32(skb, NFTA_SOCKET_KEY, htonl(priv->key)))
return -1;
if (nft_dump_register(skb, NFTA_SOCKET_DREG, priv->dreg))
return -1;
return 0;
}
static struct nft_expr_type nft_socket_type;
static const struct nft_expr_ops nft_socket_ops = {
.type = &nft_socket_type,
.size = NFT_EXPR_SIZE(sizeof(struct nft_socket)),
.eval = nft_socket_eval,
.init = nft_socket_init,
.dump = nft_socket_dump,
};
static struct nft_expr_type nft_socket_type __read_mostly = {
.name = "socket",
.ops = &nft_socket_ops,
.policy = nft_socket_policy,
.maxattr = NFTA_SOCKET_MAX,
.owner = THIS_MODULE,
};
static int __init nft_socket_module_init(void)
{
return nft_register_expr(&nft_socket_type);
}
static void __exit nft_socket_module_exit(void)
{
nft_unregister_expr(&nft_socket_type);
}
module_init(nft_socket_module_init);
module_exit(nft_socket_module_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Máté Eckl");
MODULE_DESCRIPTION("nf_tables socket match module");
MODULE_ALIAS_NFT_EXPR("socket");