path: root/net/netfilter/nfnetlink_log.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * This is a module which is used for logging packets to userspace via
 * nfetlink.
 *
 * (C) 2005 by Harald Welte <laforge@netfilter.org>
 * (C) 2006-2012 Patrick McHardy <kaber@trash.net>
 *
 * Based on the old ipv4-only ipt_ULOG.c:
 * (C) 2000-2004 by Harald Welte <laforge@netfilter.org>
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/if_arp.h>
#include <linux/init.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/netdevice.h>
#include <linux/netfilter.h>
#include <linux/netfilter_bridge.h>
#include <net/netlink.h>
#include <linux/netfilter/nfnetlink.h>
#include <linux/netfilter/nfnetlink_log.h>
#include <linux/netfilter/nf_conntrack_common.h>
#include <linux/spinlock.h>
#include <linux/sysctl.h>
#include <linux/proc_fs.h>
#include <linux/security.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <net/sock.h>
#include <net/netfilter/nf_log.h>
#include <net/netns/generic.h>

#include <linux/atomic.h>
#include <linux/refcount.h>


#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
#include "../bridge/br_private.h"
#endif

#if IS_ENABLED(CONFIG_NF_CONNTRACK)
#include <net/netfilter/nf_conntrack.h>
#endif

#define NFULNL_COPY_DISABLED	0xff
#define NFULNL_NLBUFSIZ_DEFAULT	NLMSG_GOODSIZE
#define NFULNL_TIMEOUT_DEFAULT 	100	/* every second */
#define NFULNL_QTHRESH_DEFAULT 	100	/* 100 packets */
/* max packet size is limited by 16-bit struct nfattr nfa_len field */
#define NFULNL_COPY_RANGE_MAX	(0xFFFF - NLA_HDRLEN)

#define PRINTR(x, args...)	do { if (net_ratelimit()) \
				     printk(x, ## args); } while (0);

struct nfulnl_instance {
	struct hlist_node hlist;	/* global list of instances */
	spinlock_t lock;
	refcount_t use;			/* use count */

	unsigned int qlen;		/* number of nlmsgs in skb */
	struct sk_buff *skb;		/* pre-allocatd skb */
	struct timer_list timer;
	struct net *net;
	netns_tracker ns_tracker;
	struct user_namespace *peer_user_ns;	/* User namespace of the peer process */
	u32 peer_portid;		/* PORTID of the peer process */

	/* configurable parameters */
	unsigned int flushtimeout;	/* timeout until queue flush */
	unsigned int nlbufsiz;		/* netlink buffer allocation size */
	unsigned int qthreshold;	/* threshold of the queue */
	u_int32_t copy_range;
	u_int32_t seq;			/* instance-local sequential counter */
	u_int16_t group_num;		/* number of this queue */
	u_int16_t flags;
	u_int8_t copy_mode;
	struct rcu_head rcu;
};

#define INSTANCE_BUCKETS	16

static unsigned int nfnl_log_net_id __read_mostly;

struct nfnl_log_net {
	spinlock_t instances_lock;
	struct hlist_head instance_table[INSTANCE_BUCKETS];
	atomic_t global_seq;
};

static struct nfnl_log_net *nfnl_log_pernet(struct net *net)
{
	return net_generic(net, nfnl_log_net_id);
}

static inline u_int8_t instance_hashfn(u_int16_t group_num)
{
	return ((group_num & 0xff) % INSTANCE_BUCKETS);
}

static struct nfulnl_instance *
__instance_lookup(struct nfnl_log_net *log, u_int16_t group_num)
{
	struct hlist_head *head;
	struct nfulnl_instance *inst;

	head = &log->instance_table[instance_hashfn(group_num)];
	hlist_for_each_entry_rcu(inst, head, hlist) {
		if (inst->group_num == group_num)
			return inst;
	}
	return NULL;
}

static inline void
instance_get(struct nfulnl_instance *inst)
{
	refcount_inc(&inst->use);
}

static struct nfulnl_instance *
instance_lookup_get(struct nfnl_log_net *log, u_int16_t group_num)
{
	struct nfulnl_instance *inst;

	rcu_read_lock_bh();
	inst = __instance_lookup(log, group_num);
	if (inst && !refcount_inc_not_zero(&inst->use))
		inst = NULL;
	rcu_read_unlock_bh();

	return inst;
}

static void nfulnl_instance_free_rcu(struct rcu_head *head)
{
	struct nfulnl_instance *inst =
		container_of(head, struct nfulnl_instance, rcu);

	put_net_track(inst->net, &inst->ns_tracker);
	kfree(inst);
	module_put(THIS_MODULE);
}

static void
instance_put(struct nfulnl_instance *inst)
{
	if (inst && refcount_dec_and_test(&inst->use))
		call_rcu(&inst->rcu, nfulnl_instance_free_rcu