net/netfilter/nft_socket.c - linux - Git at Google

 /* 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;
 	u8				level;		/* cgroupv2 level to extract */
 	u8				level_user;	/* cgroupv2 level provided by userspace */
 	u8				len;
 	union {
 		u8			dreg;
 	};
 };

 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;
 	}
 }

 #ifdef CONFIG_SOCK_CGROUP_DATA
 static noinline bool
 nft_sock_get_eval_cgroupv2(u32 *dest, struct sock *sk, const struct nft_pktinfo *pkt, u32 level)
 {
 	struct cgroup *cgrp;
 	u64 cgid;

 	if (!sk_fullsock(sk))
 		return false;

 	cgrp = cgroup_ancestor(sock_cgroup_ptr(&sk->sk_cgrp_data), level);
 	if (!cgrp)
 		return false;

 	cgid = cgroup_id(cgrp);
 	memcpy(dest, &cgid, sizeof(u64));
 	return true;
 }

 /* process context only, uses current->nsproxy. */
 static noinline int nft_socket_cgroup_subtree_level(void)
 {
 	struct cgroup *cgrp = cgroup_get_from_path("/");
 	int level;

 	if (IS_ERR(cgrp))
 		return PTR_ERR(cgrp);

 	level = cgrp->level;

 	cgroup_put(cgrp);

 	if (WARN_ON_ONCE(level > 255))
 		return -ERANGE;

 	if (WARN_ON_ONCE(level < 0))
 		return -EINVAL;

 	return level;
 }
 #endif

 static struct sock *nft_socket_do_lookup(const struct nft_pktinfo *pkt)
 {
 	const struct net_device *indev = nft_in(pkt);
 	const struct sk_buff *skb = pkt->skb;
 	struct sock *sk = NULL;

 	if (!indev)
 		return NULL;

 	switch (nft_pf(pkt)) {
 	case NFPROTO_IPV4:
 		sk = nf_sk_lookup_slow_v4(nft_net(pkt), skb, indev);
 		break;
 #if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
 	case NFPROTO_IPV6:
 		sk = nf_sk_lookup_slow_v6(nft_net(pkt), skb, indev);
 		break;
 #endif
 	default:
 		WARN_ON_ONCE(1);
 		break;
 	}

 	return sk;
 }

 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 = &regs->data[priv->dreg];

 	if (sk && !net_eq(nft_net(pkt), sock_net(sk)))
 		sk = NULL;

 	if (!sk)
 		sk = nft_socket_do_lookup(pkt);

 	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 = READ_ONCE(sk->sk_mark);
 		} else {
 			regs->verdict.code = NFT_BREAK;
 			goto out_put_sk;
 		}
 		break;
 	case NFT_SOCKET_WILDCARD:
 		if (!sk_fullsock(sk)) {
 			regs->verdict.code = NFT_BREAK;
 			goto out_put_sk;
 		}
 		nft_socket_wildcard(pkt, regs, sk, dest);
 		break;
 #ifdef CONFIG_SOCK_CGROUP_DATA
 	case NFT_SOCKET_CGROUPV2:
 		if (!nft_sock_get_eval_cgroupv2(dest, sk, pkt, priv->level)) {
 			regs->verdict.code = NFT_BREAK;
 			goto out_put_sk;
 		}
 		break;
 #endif
 	default:
 		WARN_ON(1);
 		regs->verdict.code = NFT_BREAK;
 	}

 out_put_sk:
 	if (sk != skb->sk)
 		sock_gen_put(sk);
 }

 static const struct nla_policy nft_socket_policy[NFTA_SOCKET_MAX + 1] = {
 	[NFTA_SOCKET_KEY]		= NLA_POLICY_MAX(NLA_BE32, 255),
 	[NFTA_SOCKET_DREG]		= { .type = NLA_U32 },
 	[NFTA_SOCKET_LEVEL]		= NLA_POLICY_MAX(NLA_BE32, 255),
 };

 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_be32(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;
 #ifdef CONFIG_SOCK_CGROUP_DATA
 	case NFT_SOCKET_CGROUPV2: {
 		unsigned int level;
 		int err;

 		if (!tb[NFTA_SOCKET_LEVEL])
 			return -EINVAL;

 		level = ntohl(nla_get_be32(tb[NFTA_SOCKET_LEVEL]));
 		if (level > 255)
 			return -EOPNOTSUPP;

 		err = nft_socket_cgroup_subtree_level();
 		if (err < 0)
 			return err;

 		priv->level_user = level;

 		level += err;
 		/* Implies a giant cgroup tree */
 		if (WARN_ON_ONCE(level > 255))
 			return -EOPNOTSUPP;

 		priv->level = level;
 		len = sizeof(u64);
 		break;
 	}
 #endif
 	default:
 		return -EOPNOTSUPP;
 	}

 	priv->len = len;
 	return nft_parse_register_store(ctx, tb[NFTA_SOCKET_DREG], &priv->dreg,
 					NULL, NFT_DATA_VALUE, len);
 }

 static int nft_socket_dump(struct sk_buff *skb,
 			   const struct nft_expr *expr, bool reset)
 {
 	const struct nft_socket *priv = nft_expr_priv(expr);

 	if (nla_put_be32(skb, NFTA_SOCKET_KEY, htonl(priv->key)))
 		return -1;
 	if (nft_dump_register(skb, NFTA_SOCKET_DREG, priv->dreg))
 		return -1;
 	if (priv->key == NFT_SOCKET_CGROUPV2 &&
 	    nla_put_be32(skb, NFTA_SOCKET_LEVEL, htonl(priv->level_user)))
 		return -1;
 	return 0;
 }

 static bool nft_socket_reduce(struct nft_regs_track *track,
 			      const struct nft_expr *expr)
 {
 	const struct nft_socket *priv = nft_expr_priv(expr);
 	const struct nft_socket *socket;

 	if (!nft_reg_track_cmp(track, expr, priv->dreg)) {
 		nft_reg_track_update(track, expr, priv->dreg, priv->len);
 		return false;
 	}

 	socket = nft_expr_priv(track->regs[priv->dreg].selector);
 	if (priv->key != socket->key ||
 	    priv->dreg != socket->dreg ||
 	    priv->level != socket->level) {
 		nft_reg_track_update(track, expr, priv->dreg, priv->len);
 		return false;
 	}

 	if (!track->regs[priv->dreg].bitwise)
 		return true;

 	return nft_expr_reduce_bitwise(track, expr);
 }

 static int nft_socket_validate(const struct nft_ctx *ctx,
 			       const struct nft_expr *expr)
 {
 	if (ctx->family != NFPROTO_IPV4 &&
 	    ctx->family != NFPROTO_IPV6 &&
 	    ctx->family != NFPROTO_INET)
 		return -EOPNOTSUPP;

 	return nft_chain_validate_hooks(ctx->chain,
 					(1 << NF_INET_PRE_ROUTING) |
 					(1 << NF_INET_LOCAL_IN) |
 					(1 << NF_INET_LOCAL_OUT));
 }

 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,
 	.validate	= nft_socket_validate,
 	.reduce		= nft_socket_reduce,
 };

 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");
	/* 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;
	u8 level; /* cgroupv2 level to extract */
	u8 level_user; /* cgroupv2 level provided by userspace */
	u8 len;
	union {
	u8 dreg;
	};
	};

	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;
	}
	}

	#ifdef CONFIG_SOCK_CGROUP_DATA
	static noinline bool
	nft_sock_get_eval_cgroupv2(u32 dest, struct sock sk, const struct nft_pktinfo *pkt, u32 level)
	{
	struct cgroup *cgrp;
	u64 cgid;

	if (!sk_fullsock(sk))
	return false;

	cgrp = cgroup_ancestor(sock_cgroup_ptr(&sk->sk_cgrp_data), level);
	if (!cgrp)
	return false;

	cgid = cgroup_id(cgrp);
	memcpy(dest, &cgid, sizeof(u64));
	return true;
	}

	/* process context only, uses current->nsproxy. */
	static noinline int nft_socket_cgroup_subtree_level(void)
	{
	struct cgroup *cgrp = cgroup_get_from_path("/");
	int level;

	if (IS_ERR(cgrp))
	return PTR_ERR(cgrp);

	level = cgrp->level;

	cgroup_put(cgrp);

	if (WARN_ON_ONCE(level > 255))
	return -ERANGE;

	if (WARN_ON_ONCE(level < 0))
	return -EINVAL;

	return level;
	}
	#endif

	static struct sock nft_socket_do_lookup(const struct nft_pktinfo pkt)
	{
	const struct net_device *indev = nft_in(pkt);
	const struct sk_buff *skb = pkt->skb;
	struct sock *sk = NULL;

	if (!indev)
	return NULL;

	switch (nft_pf(pkt)) {
	case NFPROTO_IPV4:
	sk = nf_sk_lookup_slow_v4(nft_net(pkt), skb, indev);
	break;
	#if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
	case NFPROTO_IPV6:
	sk = nf_sk_lookup_slow_v6(nft_net(pkt), skb, indev);
	break;
	#endif
	default:
	WARN_ON_ONCE(1);
	break;
	}

	return sk;
	}

	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 = &regs->data[priv->dreg];

	if (sk && !net_eq(nft_net(pkt), sock_net(sk)))
	sk = NULL;

	if (!sk)
	sk = nft_socket_do_lookup(pkt);

	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 = READ_ONCE(sk->sk_mark);
	} else {
	regs->verdict.code = NFT_BREAK;
	goto out_put_sk;
	}
	break;
	case NFT_SOCKET_WILDCARD:
	if (!sk_fullsock(sk)) {
	regs->verdict.code = NFT_BREAK;
	goto out_put_sk;
	}
	nft_socket_wildcard(pkt, regs, sk, dest);
	break;
	#ifdef CONFIG_SOCK_CGROUP_DATA
	case NFT_SOCKET_CGROUPV2:
	if (!nft_sock_get_eval_cgroupv2(dest, sk, pkt, priv->level)) {
	regs->verdict.code = NFT_BREAK;
	goto out_put_sk;
	}
	break;
	#endif
	default:
	WARN_ON(1);
	regs->verdict.code = NFT_BREAK;
	}

	out_put_sk:
	if (sk != skb->sk)
	sock_gen_put(sk);
	}

	static const struct nla_policy nft_socket_policy[NFTA_SOCKET_MAX + 1] = {
	[NFTA_SOCKET_KEY] = NLA_POLICY_MAX(NLA_BE32, 255),
	[NFTA_SOCKET_DREG] = { .type = NLA_U32 },
	[NFTA_SOCKET_LEVEL] = NLA_POLICY_MAX(NLA_BE32, 255),
	};

	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_be32(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;
	#ifdef CONFIG_SOCK_CGROUP_DATA
	case NFT_SOCKET_CGROUPV2: {
	unsigned int level;
	int err;

	if (!tb[NFTA_SOCKET_LEVEL])
	return -EINVAL;

	level = ntohl(nla_get_be32(tb[NFTA_SOCKET_LEVEL]));
	if (level > 255)
	return -EOPNOTSUPP;

	err = nft_socket_cgroup_subtree_level();
	if (err < 0)
	return err;

	priv->level_user = level;

	level += err;
	/* Implies a giant cgroup tree */
	if (WARN_ON_ONCE(level > 255))
	return -EOPNOTSUPP;

	priv->level = level;
	len = sizeof(u64);
	break;
	}
	#endif
	default:
	return -EOPNOTSUPP;
	}

	priv->len = len;
	return nft_parse_register_store(ctx, tb[NFTA_SOCKET_DREG], &priv->dreg,
	NULL, NFT_DATA_VALUE, len);
	}

	static int nft_socket_dump(struct sk_buff *skb,
	const struct nft_expr *expr, bool reset)
	{
	const struct nft_socket *priv = nft_expr_priv(expr);

	if (nla_put_be32(skb, NFTA_SOCKET_KEY, htonl(priv->key)))
	return -1;
	if (nft_dump_register(skb, NFTA_SOCKET_DREG, priv->dreg))
	return -1;
	if (priv->key == NFT_SOCKET_CGROUPV2 &&
	nla_put_be32(skb, NFTA_SOCKET_LEVEL, htonl(priv->level_user)))
	return -1;
	return 0;
	}

	static bool nft_socket_reduce(struct nft_regs_track *track,
	const struct nft_expr *expr)
	{
	const struct nft_socket *priv = nft_expr_priv(expr);
	const struct nft_socket *socket;

	if (!nft_reg_track_cmp(track, expr, priv->dreg)) {
	nft_reg_track_update(track, expr, priv->dreg, priv->len);
	return false;
	}

	socket = nft_expr_priv(track->regs[priv->dreg].selector);
	if (priv->key != socket->key \|\|
	priv->dreg != socket->dreg \|\|
	priv->level != socket->level) {
	nft_reg_track_update(track, expr, priv->dreg, priv->len);
	return false;
	}

	if (!track->regs[priv->dreg].bitwise)
	return true;

	return nft_expr_reduce_bitwise(track, expr);
	}

	static int nft_socket_validate(const struct nft_ctx *ctx,
	const struct nft_expr *expr)
	{
	if (ctx->family != NFPROTO_IPV4 &&
	ctx->family != NFPROTO_IPV6 &&
	ctx->family != NFPROTO_INET)
	return -EOPNOTSUPP;

	return nft_chain_validate_hooks(ctx->chain,
	(1 << NF_INET_PRE_ROUTING) \|
	(1 << NF_INET_LOCAL_IN) \|
	(1 << NF_INET_LOCAL_OUT));
	}

	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,
	.validate = nft_socket_validate,
	.reduce = nft_socket_reduce,
	};

	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");