[NETFILTER]: Add new "nfnetlink_log" userspace packet logging facility

This is a generic (layer3 independent) version of what ipt_ULOG is already
doing for IPv4 today.  ipt_ULOG, ebt_ulog and finally also ip[6]t_LOG will
be deprecated by this mechanism in the long term.
Signed-off-by: Harald Welte <laforge@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/netfilter/nfnetlink_log.h

+#ifndef _NFNETLINK_LOG_H
+#define _NFNETLINK_LOG_H
+
+/* This file describes the netlink messages (i.e. 'protocol packets'),
+ * and not any kind of function definitions.  It is shared between kernel and
+ * userspace.  Don't put kernel specific stuff in here */
+
+#include <linux/netfilter/nfnetlink.h>
+
+enum nfulnl_msg_types {
+	NFULNL_MSG_PACKET,		/* packet from kernel to userspace */
+	NFULNL_MSG_CONFIG,		/* connect to a particular queue */
+
+	NFULNL_MSG_MAX
+};
+
+struct nfulnl_msg_packet_hdr {
+	u_int16_t	hw_protocol;	/* hw protocol (network order) */
+	u_int8_t	hook;		/* netfilter hook */
+	u_int8_t	_pad;
+} __attribute__ ((packed));
+
+struct nfulnl_msg_packet_hw {
+	u_int16_t	hw_addrlen;
+	u_int16_t	_pad;
+	u_int8_t	hw_addr[8];
+} __attribute__ ((packed));
+
+struct nfulnl_msg_packet_timestamp {
+	u_int64_t	sec;
+	u_int64_t	usec;
+} __attribute__ ((packed));
+
+#define NFULNL_PREFIXLEN	30	/* just like old log target */
+
+enum nfulnl_attr_type {
+	NFULA_UNSPEC,
+	NFULA_PACKET_HDR,
+	NFULA_MARK,			/* u_int32_t nfmark */
+	NFULA_TIMESTAMP,		/* nfulnl_msg_packet_timestamp */
+	NFULA_IFINDEX_INDEV,		/* u_int32_t ifindex */
+	NFULA_IFINDEX_OUTDEV,		/* u_int32_t ifindex */
+	NFULA_HWADDR,			/* nfulnl_msg_packet_hw */
+	NFULA_PAYLOAD,			/* opaque data payload */
+	NFULA_PREFIX,			/* string prefix */
+	NFULA_UID,			/* user id of socket */
+
+	__NFULA_MAX
+};
+#define NFULA_MAX (__NFULA_MAX - 1)
+
+enum nfulnl_msg_config_cmds {
+	NFULNL_CFG_CMD_NONE,
+	NFULNL_CFG_CMD_BIND,
+	NFULNL_CFG_CMD_UNBIND,
+	NFULNL_CFG_CMD_PF_BIND,
+	NFULNL_CFG_CMD_PF_UNBIND,
+};
+
+struct nfulnl_msg_config_cmd {
+	u_int8_t	command;	/* nfulnl_msg_config_cmds */
+} __attribute__ ((packed));
+
+struct nfulnl_msg_config_mode {
+	u_int32_t	copy_range;
+	u_int8_t	copy_mode;
+	u_int8_t	_pad;
+} __attribute__ ((packed));
+
+enum nfulnl_attr_config {
+	NFULA_CFG_UNSPEC,
+	NFULA_CFG_CMD,			/* nfulnl_msg_config_cmd */
+	NFULA_CFG_MODE,			/* nfulnl_msg_config_mode */
+	NFULA_CFG_NLBUFSIZ,		/* u_int32_t buffer size */
+	NFULA_CFG_TIMEOUT,		/* u_int32_t in 1/100 s */
+	NFULA_CFG_QTHRESH,		/* u_int32_t */
+	__NFULA_CFG_MAX
+};
+#define NFULA_CFG_MAX (__NFULA_CFG_MAX -1)
+
+#define NFULNL_COPY_NONE	0x00
+#define NFULNL_COPY_META	0x01
+#define NFULNL_COPY_PACKET	0x02
+
+#endif /* _NFNETLINK_LOG_H */

net/netfilter/Kconfig

@@ -11,3 +11,14 @@ config NETFILTER_NETLINK_QUEUE
 	  If this option isenabled, the kernel will include support
 	  for queueing packets via NFNETLINK.
 	  
+config NETFILTER_NETLINK_LOG
+	tristate "Netfilter LOG over NFNETLINK interface"
+	depends on NETFILTER_NETLINK
+	help
+	  If this option is enabled, the kernel will include support
+	  for logging packets via NFNETLINK.
+
+	  This obsoletes the existing ipt_ULOG and ebg_ulog mechanisms,
+	  and is also scheduled to replace the old syslog-based ipt_LOG
+	  and ip6t_LOG modules.
+

net/netfilter/Makefile

 obj-$(CONFIG_NETFILTER_NETLINK) += nfnetlink.o
 obj-$(CONFIG_NETFILTER_NETLINK_QUEUE) += nfnetlink_queue.o
+obj-$(CONFIG_NETFILTER_NETLINK_LOG) += nfnetlink_log.o

net/netfilter/nfnetlink_log.c

+/*
+ * This is a module which is used for logging packets to userspace via
+ * nfetlink.
+ *
+ * (C) 2005 by Harald Welte <laforge@netfilter.org>
+ *
+ * Based on the old ipv4-only ipt_ULOG.c:
+ * (C) 2000-2004 by Harald Welte <laforge@netfilter.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/init.h>
+#include <linux/ip.h>
+#include <linux/ipv6.h>
+#include <linux/netdevice.h>
+#include <linux/netfilter.h>
+#include <linux/netlink.h>
+#include <linux/netfilter/nfnetlink.h>
+#include <linux/netfilter/nfnetlink_log.h>
+#include <linux/spinlock.h>
+#include <linux/sysctl.h>
+#include <linux/proc_fs.h>
+#include <linux/security.h>
+#include <linux/list.h>
+#include <linux/jhash.h>
+#include <linux/random.h>
+#include <net/sock.h>
+
+#include <asm/atomic.h>
+
+#define NFULNL_NLBUFSIZ_DEFAULT	4096
+#define NFULNL_TIMEOUT_DEFAULT 	100	/* every second */
+#define NFULNL_QTHRESH_DEFAULT 	100	/* 100 packets */
+
+#define PRINTR(x, args...)	do { if (net_ratelimit()) \
+				     printk(x, ## args); } while (0);
+
+#if 0
+#define UDEBUG(x, args ...)	printk(KERN_DEBUG "%s(%d):%s():	" x, 	   \
+					__FILE__, __LINE__, __FUNCTION__,  \
+					## args)
+#else
+#define UDEBUG(x, ...)
+#endif
+
+struct nfulnl_instance {
+	struct hlist_node hlist;	/* global list of instances */
+	spinlock_t lock;
+	atomic_t use;			/* use count */
+
+	unsigned int qlen;		/* number of nlmsgs in skb */
+	struct sk_buff *skb;		/* pre-allocatd skb */
+	struct nlmsghdr *lastnlh;	/* netlink header of last msg in skb */
+	struct timer_list timer;
+	int peer_pid;			/* PID 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_int16_t group_num;		/* number of this queue */
+	u_int8_t copy_mode;	
+};
+
+static DEFINE_RWLOCK(instances_lock);
+
+#define INSTANCE_BUCKETS	16
+static struct hlist_head instance_table[INSTANCE_BUCKETS];
+static unsigned int hash_init;
+
+static inline u_int8_t instance_hashfn(u_int16_t group_num)
+{
+	return ((group_num & 0xff) % INSTANCE_BUCKETS);
+}
+
+static struct nfulnl_instance *
+__instance_lookup(u_int16_t group_num)
+{
+	struct hlist_head *head;
+	struct hlist_node *pos;
+	struct nfulnl_instance *inst;
+
+	UDEBUG("entering (group_num=%u)\n", group_num);
+
+	head = &instance_table[instance_hashfn(group_num)];
+	hlist_for_each_entry(inst, pos, head, hlist) {
+		if (inst->group_num == group_num)
+			return inst;
+	}
+	return NULL;
+}
+
+static inline void
+instance_get(struct nfulnl_instance *inst)
+{
+	atomic_inc(&inst->use);
+}
+
+static struct nfulnl_instance *
+instance_lookup_get(u_int16_t group_num)
+{
+	struct nfulnl_instance *inst;
+
+	read_lock_bh(&instances_lock);
+	inst = __instance_lookup(group_num);
+	if (inst)
+		instance_get(inst);
+	read_unlock_bh(&instances_lock);
+
+	return inst;
+}
+
+static void
+instance_put(struct nfulnl_instance *inst)
+{
+	if (inst && atomic_dec_and_test(&inst->use)) {
+		UDEBUG("kfree(inst=%p)\n", inst);
+		kfree(inst);
+	}
+}
+
+static void nfulnl_timer(unsigned long data);
+
+static struct nfulnl_instance *
+instance_create(u_int16_t group_num, int pid)
+{
+	struct nfulnl_instance *inst;
+
+	UDEBUG("entering (group_num=%u, pid=%d)\n", group_num,
+		pid);
+
+	write_lock_bh(&instances_lock);	
+	if (__instance_lookup(group_num)) {
+		inst = NULL;
+		UDEBUG("aborting, instance already exists\n");
+		goto out_unlock;
+	}
+
+	inst = kmalloc(sizeof(*inst), GFP_ATOMIC);
+	if (!inst)
+		goto out_unlock;
+
+	memset(inst, 0, sizeof(*inst));
+	INIT_HLIST_NODE(&inst->hlist);
+	inst->lock = SPIN_LOCK_UNLOCKED;
+	/* needs to be two, since we _put() after creation */
+	atomic_set(&inst->use, 2);
+
+	init_timer(&inst->timer);
+	inst->timer.function = nfulnl_timer;
+	inst->timer.data = (unsigned long)inst;
+	/* don't start timer yet. (re)start it  with every packet */
+
+	inst->peer_pid = pid;
+	inst->group_num = group_num;
+
+	inst->qthreshold 	= NFULNL_QTHRESH_DEFAULT;
+	inst->flushtimeout 	= NFULNL_TIMEOUT_DEFAULT;
+	inst->nlbufsiz 		= NFULNL_NLBUFSIZ_DEFAULT;
+	inst->copy_mode 	= NFULNL_COPY_PACKET;
+	inst->copy_range 	= 0xffff;
+
+	if (!try_module_get(THIS_MODULE))
+		goto out_free;
+
+	hlist_add_head(&inst->hlist, 
+		       &instance_table[instance_hashfn(group_num)]);
+
+	UDEBUG("newly added node: %p, next=%p\n", &inst->hlist, 
+		inst->hlist.next);
+
+	write_unlock_bh(&instances_lock);
+
+	return inst;
+
+out_free:
+	instance_put(inst);
+out_unlock:
+	write_unlock_bh(&instances_lock);
+	return NULL;
+}
+
+static int __nfulnl_send(struct nfulnl_instance *inst);
+
+static void
+_instance_destroy2(struct nfulnl_instance *inst, int lock)
+{
+	/* first pull it out of the global list */
+	if (lock)
+		write_lock_bh(&instances_lock);
+
+	UDEBUG("removing instance %p (queuenum=%u) from hash\n",
+		inst, inst->group_num);
+
+	hlist_del(&inst->hlist);
+
+	if (lock)
+		write_unlock_bh(&instances_lock);
+
+	/* then flush all pending packets from skb */
+
+	spin_lock_bh(&inst->lock);
+	if (inst->skb) {
+		if (inst->qlen)
+			__nfulnl_send(inst);
+		if (inst->skb) {
+			kfree_skb(inst->skb);
+			inst->skb = NULL;
+		}
+	}
+	spin_unlock_bh(&inst->lock);
+
+	/* and finally put the refcount */
+	instance_put(inst);
+
+	module_put(THIS_MODULE);
+}
+
+static inline void
+__instance_destroy(struct nfulnl_instance *inst)
+{
+	_instance_destroy2(inst, 0);
+}
+
+static inline void
+instance_destroy(struct nfulnl_instance *inst)
+{
+	_instance_destroy2(inst, 1);
+}
+
+static int
+nfulnl_set_mode(struct nfulnl_instance *inst, u_int8_t mode,
+		  unsigned int range)
+{
+	int status = 0;
+
+	spin_lock_bh(&inst->lock);
+	
+	switch (mode) {
+	case NFULNL_COPY_NONE:
+	case NFULNL_COPY_META:
+		inst->copy_mode = mode;
+		inst->copy_range = 0;
+		break;
+		
+	case NFULNL_COPY_PACKET:
+		inst->copy_mode = mode;
+		/* we're using struct nfattr which has 16bit nfa_len */
+		if (range > 0xffff)
+			inst->copy_range = 0xffff;
+		else
+			inst->copy_range = range;
+		break;
+		
+	default:
+		status = -EINVAL;
+		break;
+	}
+
+	spin_unlock_bh(&inst->lock);
+
+	return status;
+}
+
+static int
+nfulnl_set_nlbufsiz(struct nfulnl_instance *inst, u_int32_t nlbufsiz)
+{
+	int status;
+
+	spin_lock_bh(&inst->lock);
+	if (nlbufsiz < NFULNL_NLBUFSIZ_DEFAULT)
+		status = -ERANGE;
+	else if (nlbufsiz > 131072)
+		status = -ERANGE;
+	else {
+		inst->nlbufsiz = nlbufsiz;
+		status = 0;
+	}
+	spin_unlock_bh(&inst->lock);
+
+	return status;
+}
+
+static int
+nfulnl_set_timeout(struct nfulnl_instance *inst, u_int32_t timeout)
+{
+	spin_lock_bh(&inst->lock);
+	inst->flushtimeout = timeout;
+	spin_unlock_bh(&inst->lock);
+
+	return 0;
+}
+
+static int
+nfulnl_set_qthresh(struct nfulnl_instance *inst, u_int32_t qthresh)
+{
+	spin_lock_bh(&inst->lock);
+	inst->qthreshold = qthresh;
+	spin_unlock_bh(&inst->lock);
+
+	return 0;
+}
+
+static struct sk_buff *nfulnl_alloc_skb(unsigned int inst_size, 
+					unsigned int pkt_size)
+{
+	struct sk_buff *skb;
+
+	UDEBUG("entered (%u, %u)\n", inst_size, pkt_size);
+
+	/* alloc skb which should be big enough for a whole multipart
+	 * message.  WARNING: has to be <= 128k due to slab restrictions */
+
+	skb = alloc_skb(inst_size, GFP_ATOMIC);
+	if (!skb) {
+		PRINTR("nfnetlink_log: can't alloc whole buffer (%u bytes)\n",
+			inst_size);
+
+		/* try to allocate only as much as we need for current
+		 * packet */
+
+		skb = alloc_skb(pkt_size, GFP_ATOMIC);
+		if (!skb)
+			PRINTR("nfnetlink_log: can't even alloc %u bytes\n",
+				pkt_size);
+	}
+
+	return skb;
+}
+
+static int
+__nfulnl_send(struct nfulnl_instance *inst)
+{
+	int status;
+
+	if (timer_pending(&inst->timer))
+		del_timer(&inst->timer);
+
+	if (inst->qlen > 1)
+		inst->lastnlh->nlmsg_type = NLMSG_DONE;
+
+	status = nfnetlink_unicast(inst->skb, inst->peer_pid, MSG_DONTWAIT);
+	if (status < 0) {
+		UDEBUG("netlink_unicast() failed\n");
+		/* FIXME: statistics */
+	}
+
+	inst->qlen = 0;
+	inst->skb = NULL;
+	inst->lastnlh = NULL;
+
+	return status;
+}
+
+static void nfulnl_timer(unsigned long data)
+{
+	struct nfulnl_instance *inst = (struct nfulnl_instance *)data; 
+
+	UDEBUG("timer function called, flushing buffer\n");
+
+	spin_lock_bh(&inst->lock);
+	__nfulnl_send(inst);
+	instance_put(inst);
+	spin_unlock_bh(&inst->lock);
+}
+
+static inline int 
+__build_packet_message(struct nfulnl_instance *inst,
+			const struct sk_buff *skb, 
+			unsigned int data_len,
+			unsigned int pf,
+			unsigned int hooknum,
+			const struct net_device *indev,
+			const struct net_device *outdev,
+			const struct nf_loginfo *li,
+			const char *prefix)
+{
+	unsigned char *old_tail;
+	struct nfulnl_msg_packet_hdr pmsg;
+	struct nlmsghdr *nlh;
+	struct nfgenmsg *nfmsg;
+	u_int32_t tmp_uint;
+
+	UDEBUG("entered\n");
+		
+	old_tail = inst->skb->tail;
+	nlh = NLMSG_PUT(inst->skb, 0, 0, 
+			NFNL_SUBSYS_ULOG << 8 | NFULNL_MSG_PACKET,
+			sizeof(struct nfgenmsg));
+	nfmsg = NLMSG_DATA(nlh);
+	nfmsg->nfgen_family = pf;
+	nfmsg->version = NFNETLINK_V0;
+	nfmsg->res_id = htons(inst->group_num);
+
+	pmsg.hw_protocol	= htons(skb->protocol);
+	pmsg.hook		= hooknum;
+
+	NFA_PUT(inst->skb, NFULA_PACKET_HDR, sizeof(pmsg), &pmsg);
+
+	if (prefix) {
+		int slen = strlen(prefix);
+		if (slen > NFULNL_PREFIXLEN)
+			slen = NFULNL_PREFIXLEN;
+		NFA_PUT(inst->skb, NFULA_PREFIX, slen, prefix);
+	}
+
+	if (indev) {
+		tmp_uint = htonl(indev->ifindex);
+		NFA_PUT(inst->skb, NFULA_IFINDEX_INDEV, sizeof(tmp_uint),
+			&tmp_uint);
+	}
+
+	if (outdev) {
+		tmp_uint = htonl(outdev->ifindex);
+		NFA_PUT(inst->skb, NFULA_IFINDEX_OUTDEV, sizeof(tmp_uint),
+			&tmp_uint);
+	}
+
+	if (skb->nfmark) {
+		tmp_uint = htonl(skb->nfmark);
+		NFA_PUT(inst->skb, NFULA_MARK, sizeof(tmp_uint), &tmp_uint);
+	}
+
+	if (indev && skb->dev && skb->dev->hard_header_parse) {
+		struct nfulnl_msg_packet_hw phw;
+
+		phw.hw_addrlen = 
+			skb->dev->hard_header_parse((struct sk_buff *)skb, 
+						    phw.hw_addr);
+		phw.hw_addrlen = htons(phw.hw_addrlen);
+		NFA_PUT(inst->skb, NFULA_HWADDR, sizeof(phw), &phw);
+	}
+
+	if (skb->stamp.tv_sec) {
+		struct nfulnl_msg_packet_timestamp ts;
+
+		ts.sec = cpu_to_be64(skb->stamp.tv_sec);
+		ts.usec = cpu_to_be64(skb->stamp.tv_usec);
+
+		NFA_PUT(inst->skb, NFULA_TIMESTAMP, sizeof(ts), &ts);
+	}
+
+	/* UID */
+	if (skb->sk) {
+		read_lock_bh(&skb->sk->sk_callback_lock);
+		if (skb->sk->sk_socket && skb->sk->sk_socket->file) {
+			u_int32_t uid = htonl(skb->sk->sk_socket->file->f_uid);
+			/* need to unlock here since NFA_PUT may goto */
+			read_unlock_bh(&skb->sk->sk_callback_lock);
+			NFA_PUT(inst->skb, NFULA_UID, sizeof(uid), &uid);
+		} else
+			read_unlock_bh(&skb->sk->sk_callback_lock);
+	}
+
+	if (data_len) {
+		struct nfattr *nfa;
+		int size = NFA_LENGTH(data_len);
+
+		if (skb_tailroom(inst->skb) < (int)NFA_SPACE(data_len)) {
+			printk(KERN_WARNING "nfnetlink_log: no tailroom!\n");
+			goto nlmsg_failure;
+		}
+
+		nfa = (struct nfattr *)skb_put(inst->skb, NFA_ALIGN(size));
+		nfa->nfa_type = NFULA_PAYLOAD;
+		nfa->nfa_len = size;
+
+		if (skb_copy_bits(skb, 0, NFA_DATA(nfa), data_len))
+			BUG();
+	}
+		
+	nlh->nlmsg_len = inst->skb->tail - old_tail;
+	return 0;
+
+nlmsg_failure:
+	UDEBUG("nlmsg_failure\n");
+nfattr_failure:
+	PRINTR(KERN_ERR "nfnetlink_log: error creating log nlmsg\n");
+	return -1;
+}
+
+#define RCV_SKB_FAIL(err) do { netlink_ack(skb, nlh, (err)); return; } while (0)
+
+static struct nf_loginfo default_loginfo = {
+	.type =		NF_LOG_TYPE_ULOG,
+	.u = {
+		.ulog = {
+			.copy_len	= 0xffff,
+			.group		= 0,
+			.qthreshold	= 1,
+		},
+	},
+};
+
+/* log handler for internal netfilter logging api */
+static void
+nfulnl_log_packet(unsigned int pf,
+		  unsigned int hooknum,
+		  const struct sk_buff *skb,
+		  const struct net_device *in,
+		  const struct net_device *out,
+		  const struct nf_loginfo *li_user,
+		  const char *prefix)
+{
+	unsigned int size, data_len;
+	struct nfulnl_instance *inst;
+	const struct nf_loginfo *li;
+	unsigned int qthreshold;
+	unsigned int nlbufsiz;
+
+	if (li_user && li_user->type == NF_LOG_TYPE_ULOG) 
+		li = li_user;
+	else
+		li = &default_loginfo;
+
+	inst = instance_lookup_get(li->u.ulog.group);
+	if (!inst)
+		inst = instance_lookup_get(0);
+	if (!inst) {
+		PRINTR("nfnetlink_log: trying to log packet, "
+			"but no instance for group %u\n", li->u.ulog.group);
+		return;
+	}
+
+	/* all macros expand to constant values at compile time */
+	/* FIXME: do we want to make the size calculation conditional based on
+	 * what is actually present?  way more branches and checks, but more
+	 * memory efficient... */
+	size =    NLMSG_SPACE(sizeof(struct nfgenmsg))
+		+ NFA_SPACE(sizeof(struct nfulnl_msg_packet_hdr))
+		+ NFA_SPACE(sizeof(u_int32_t))	/* ifindex */
+		+ NFA_SPACE(sizeof(u_int32_t))	/* ifindex */
+		+ NFA_SPACE(sizeof(u_int32_t))	/* mark */
+		+ NFA_SPACE(sizeof(u_int32_t))	/* uid */
+		+ NFA_SPACE(NFULNL_PREFIXLEN)	/* prefix */
+		+ NFA_SPACE(sizeof(struct nfulnl_msg_packet_hw))
+		+ NFA_SPACE(sizeof(struct nfulnl_msg_packet_timestamp));
+
+	UDEBUG("initial size=%u\n", size);
+
+	spin_lock_bh(&inst->lock);
+
+	qthreshold = inst->qthreshold;
+	/* per-rule qthreshold overrides per-instance */
+	if (qthreshold > li->u.ulog.qthreshold)
+		qthreshold = li->u.ulog.qthreshold;
+	
+	switch (inst->copy_mode) {
+	case NFULNL_COPY_META:
+	case NFULNL_COPY_NONE:
+		data_len = 0;
+		break;
+	
+	case NFULNL_COPY_PACKET:
+		if (inst->copy_range == 0 
+		    || inst->copy_range > skb->len)
+			data_len = skb->len;
+		else
+			data_len = inst->copy_range;
+		
+		size += NFA_SPACE(data_len);
+		UDEBUG("copy_packet, therefore size now %u\n", size);
+		break;
+	
+	default:
+		spin_unlock_bh(&inst->lock);
+		instance_put(inst);
+		return;
+	}
+
+	if (size > inst->nlbufsiz)
+		nlbufsiz = size;
+	else
+		nlbufsiz = inst->nlbufsiz;
+
+	if (!inst->skb) {
+		if (!(inst->skb = nfulnl_alloc_skb(nlbufsiz, size))) {
+			UDEBUG("error in nfulnl_alloc_skb(%u, %u)\n",
+				inst->nlbufsiz, size);
+			goto alloc_failure;
+		}
+	} else if (inst->qlen >= qthreshold ||
+		   size > skb_tailroom(inst->skb)) {
+		/* either the queue len is too high or we don't have
+		 * enough room in the skb left. flush to userspace. */
+		UDEBUG("flushing old skb\n");
+
+		__nfulnl_send(inst);
+
+		if (!(inst->skb = nfulnl_alloc_skb(nlbufsiz, size))) {
+			UDEBUG("error in nfulnl_alloc_skb(%u, %u)\n",
+				inst->nlbufsiz, size);
+			goto alloc_failure;
+		}
+	}
+
+	UDEBUG("qlen %d, qthreshold %d\n", inst->qlen, qthreshold);
+	inst->qlen++;
+
+	__build_packet_message(inst, skb, data_len, pf,
+				hooknum, in, out, li, prefix);
+
+	/* timer_pending always called within inst->lock, so there
+	 * is no chance of a race here */
+	if (!timer_pending(&inst->timer)) {
+		instance_get(inst);
+		inst->timer.expires = jiffies + (inst->flushtimeout*HZ/100);
+		add_timer(&inst->timer);
+	}
+	spin_unlock_bh(&inst->lock);
+
+	return;
+
+alloc_failure:
+	spin_unlock_bh(&inst->lock);
+	instance_put(inst);
+	UDEBUG("error allocating skb\n");
+	/* FIXME: statistics */
+}
+
+static int
+nfulnl_rcv_nl_event(struct notifier_block *this,
+		   unsigned long event, void *ptr)
+{
+	struct netlink_notify *n = ptr;
+
+	if (event == NETLINK_URELEASE &&
+	    n->protocol == NETLINK_NETFILTER && n->pid) {
+		int i;
+
+		/* destroy all instances for this pid */
+		write_lock_bh(&instances_lock);
+		for  (i = 0; i < INSTANCE_BUCKETS; i++) {
+			struct hlist_node *tmp, *t2;
+			struct nfulnl_instance *inst;
+			struct hlist_head *head = &instance_table[i];
+
+			hlist_for_each_entry_safe(inst, tmp, t2, head, hlist) {
+				UDEBUG("node = %p\n", inst);
+				if (n->pid == inst->peer_pid)
+					__instance_destroy(inst);
+			}
+		}
+		write_unlock_bh(&instances_lock);
+	}
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block nfulnl_rtnl_notifier = {
+	.notifier_call	= nfulnl_rcv_nl_event,
+};
+
+static int
+nfulnl_recv_unsupp(struct sock *ctnl, struct sk_buff *skb,
+		  struct nlmsghdr *nlh, struct nfattr *nfqa[], int *errp)
+{
+	return -ENOTSUPP;
+}
+
+static struct nf_logger nfulnl_logger = {
+	.name	= "nfnetlink_log",
+	.logfn	= &nfulnl_log_packet,
+	.me	= THIS_MODULE,
+};
+
+static const int nfula_min[NFULA_MAX] = {
+	[NFULA_PACKET_HDR-1]	= sizeof(struct nfulnl_msg_packet_hdr),
+	[NFULA_MARK-1]		= sizeof(u_int32_t),
+	[NFULA_TIMESTAMP-1]	= sizeof(struct nfulnl_msg_packet_timestamp),
+	[NFULA_IFINDEX_INDEV-1]	= sizeof(u_int32_t),
+	[NFULA_IFINDEX_OUTDEV-1]= sizeof(u_int32_t),
+	[NFULA_HWADDR-1]	= sizeof(struct nfulnl_msg_packet_hw),
+	[NFULA_PAYLOAD-1]	= 0,
+	[NFULA_PREFIX-1]	= 0,
+	[NFULA_UID-1]		= sizeof(u_int32_t),
+};
+
+static const int nfula_cfg_min[NFULA_CFG_MAX] = {
+	[NFULA_CFG_CMD-1]	= sizeof(struct nfulnl_msg_config_cmd),
+	[NFULA_CFG_MODE-1]	= sizeof(struct nfulnl_msg_config_mode),
+	[NFULA_CFG_TIMEOUT-1]	= sizeof(u_int32_t),
+	[NFULA_CFG_QTHRESH-1]	= sizeof(u_int32_t),
+	[NFULA_CFG_NLBUFSIZ-1]	= sizeof(u_int32_t),
+};
+
+static int
+nfulnl_recv_config(struct sock *ctnl, struct sk_buff *skb,
+		   struct nlmsghdr *nlh, struct nfattr *nfula[], int *errp)
+{
+	struct nfgenmsg *nfmsg = NLMSG_DATA(nlh);
+	u_int16_t group_num = ntohs(nfmsg->res_id);
+	struct nfulnl_instance *inst;
+	int ret = 0;
+
+	UDEBUG("entering for msg %u\n", NFNL_MSG_TYPE(nlh->nlmsg_type));
+
+	if (nfattr_bad_size(nfula, NFULA_CFG_MAX, nfula_cfg_min)) {
+		UDEBUG("bad attribute size\n");
+		return -EINVAL;
+	}
+
+	inst = instance_lookup_get(group_num);
+	if (nfula[NFULA_CFG_CMD-1]) {
+		u_int8_t pf = nfmsg->nfgen_family;
+		struct nfulnl_msg_config_cmd *cmd;
+		cmd = NFA_DATA(nfula[NFULA_CFG_CMD-1]);
+		UDEBUG("found CFG_CMD for\n");
+
+		switch (cmd->command) {
+		case NFULNL_CFG_CMD_BIND:
+			if (inst) {
+				ret = -EBUSY;
+				goto out_put;
+			}
+
+			inst = instance_create(group_num,
+					       NETLINK_CB(skb).pid);
+			if (!inst) {
+				ret = -EINVAL;
+				goto out_put;
+			}
+			break;
+		case NFULNL_CFG_CMD_UNBIND:
+			if (!inst) {
+				ret = -ENODEV;
+				goto out_put;
+			}
+
+			if (inst->peer_pid != NETLINK_CB(skb).pid) {
+				ret = -EPERM;
+				goto out_put;
+			}
+
+			instance_destroy(inst);
+			break;
+		case NFULNL_CFG_CMD_PF_BIND:
+			UDEBUG("registering log handler for pf=%u\n", pf);
+			ret = nf_log_register(pf, &nfulnl_logger);
+			break;
+		case NFULNL_CFG_CMD_PF_UNBIND:
+			UDEBUG("unregistering log handler for pf=%u\n", pf);
+			/* This is a bug and a feature.  We cannot unregister
+			 * other handlers, like nfnetlink_inst can */
+			nf_log_unregister_pf(pf);
+			break;
+		default:
+			ret = -EINVAL;
+			break;
+		}
+	} else {
+		if (!inst) {
+			UDEBUG("no config command, and no instance for "
+				"group=%u pid=%u =>ENOENT\n",
+				group_num, NETLINK_CB(skb).pid);
+			ret = -ENOENT;
+			goto out_put;
+		}
+
+		if (inst->peer_pid != NETLINK_CB(skb).pid) {
+			UDEBUG("no config command, and wrong pid\n");
+			ret = -EPERM;
+			goto out_put;
+		}
+	}
+
+	if (nfula[NFULA_CFG_MODE-1]) {
+		struct nfulnl_msg_config_mode *params;
+		params = NFA_DATA(nfula[NFULA_CFG_MODE-1]);
+
+		nfulnl_set_mode(inst, params->copy_mode,
+				ntohs(params->copy_range));
+	}
+
+	if (nfula[NFULA_CFG_TIMEOUT-1]) {
+		u_int32_t timeout = 
+			*(u_int32_t *)NFA_DATA(nfula[NFULA_CFG_TIMEOUT-1]);
+
+		nfulnl_set_timeout(inst, ntohl(timeout));
+	}
+
+	if (nfula[NFULA_CFG_NLBUFSIZ-1]) {
+		u_int32_t nlbufsiz = 
+			*(u_int32_t *)NFA_DATA(nfula[NFULA_CFG_NLBUFSIZ-1]);
+
+		nfulnl_set_nlbufsiz(inst, ntohl(nlbufsiz));
+	}
+
+	if (nfula[NFULA_CFG_QTHRESH-1]) {
+		u_int32_t qthresh = 
+			*(u_int16_t *)NFA_DATA(nfula[NFULA_CFG_QTHRESH-1]);
+
+		nfulnl_set_qthresh(inst, ntohl(qthresh));
+	}
+
+out_put:
+	instance_put(inst);
+	return ret;
+}
+
+static struct nfnl_callback nfulnl_cb[NFULNL_MSG_MAX] = {
+	[NFULNL_MSG_PACKET]	= { .call = nfulnl_recv_unsupp,
+				    .cap_required = CAP_NET_ADMIN },
+	[NFULNL_MSG_CONFIG]	= { .call = nfulnl_recv_config,
+				    .cap_required = CAP_NET_ADMIN },
+};
+
+static struct nfnetlink_subsystem nfulnl_subsys = {
+	.name		= "log",
+	.subsys_id	= NFNL_SUBSYS_ULOG,
+	.cb_count	= NFULNL_MSG_MAX,
+	.attr_count	= NFULA_MAX,
+	.cb		= nfulnl_cb,
+};
+
+#ifdef CONFIG_PROC_FS
+struct iter_state {
+	unsigned int bucket;
+};
+
+static struct hlist_node *get_first(struct seq_file *seq)
+{
+	struct iter_state *st = seq->private;
+
+	if (!st)
+		return NULL;
+
+	for (st->bucket = 0; st->bucket < INSTANCE_BUCKETS; st->bucket++) {
+		if (!hlist_empty(&instance_table[st->bucket]))
+			return instance_table[st->bucket].first;
+	}
+	return NULL;
+}
+
+static struct hlist_node *get_next(struct seq_file *seq, struct hlist_node *h)
+{
+	struct iter_state *st = seq->private;
+
+	h = h->next;
+	while (!h) {
+		if (++st->bucket >= INSTANCE_BUCKETS)
+			return NULL;
+
+		h = instance_table[st->bucket].first;
+	}
+	return h;
+}
+
+static struct hlist_node *get_idx(struct seq_file *seq, loff_t pos)
+{
+	struct hlist_node *head;
+	head = get_first(seq);
+
+	if (head)
+		while (pos && (head = get_next(seq, head)))
+			pos--;
+	return pos ? NULL : head;
+}
+
+static void *seq_start(struct seq_file *seq, loff_t *pos)
+{
+	read_lock_bh(&instances_lock);
+	return get_idx(seq, *pos);
+}
+
+static void *seq_next(struct seq_file *s, void *v, loff_t *pos)
+{
+	(*pos)++;
+	return get_next(s, v);
+}
+
+static void seq_stop(struct seq_file *s, void *v)
+{
+	read_unlock_bh(&instances_lock);
+}
+
+static int seq_show(struct seq_file *s, void *v)
+{
+	const struct nfulnl_instance *inst = v;
+
+	return seq_printf(s, "%5d %6d %5d %1d %5d %6d %2d\n", 
+			  inst->group_num,
+			  inst->peer_pid, inst->qlen, 
+			  inst->copy_mode, inst->copy_range,
+			  inst->flushtimeout, atomic_read(&inst->use));
+}
+
+static struct seq_operations nful_seq_ops = {
+	.start	= seq_start,
+	.next	= seq_next,
+	.stop	= seq_stop,
+	.show	= seq_show,
+};
+
+static int nful_open(struct inode *inode, struct file *file)
+{
+	struct seq_file *seq;
+	struct iter_state *is;
+	int ret;
+
+	is = kmalloc(sizeof(*is), GFP_KERNEL);
+	if (!is)
+		return -ENOMEM;
+	memset(is, 0, sizeof(*is));
+	ret = seq_open(file, &nful_seq_ops);
+	if (ret < 0)
+		goto out_free;
+	seq = file->private_data;
+	seq->private = is;
+	return ret;
+out_free:
+	kfree(is);
+	return ret;
+}
+
+static struct file_operations nful_file_ops = {
+	.owner	 = THIS_MODULE,
+	.open	 = nful_open,
+	.read	 = seq_read,
+	.llseek	 = seq_lseek,
+	.release = seq_release_private,
+};
+
+#endif /* PROC_FS */
+
+static int
+init_or_cleanup(int init)
+{
+	int i, status = -ENOMEM;
+#ifdef CONFIG_PROC_FS
+	struct proc_dir_entry *proc_nful;
+#endif
+	
+	if (!init)
+		goto cleanup;
+
+	for (i = 0; i < INSTANCE_BUCKETS; i++)
+		INIT_HLIST_HEAD(&instance_table[i]);
+	
+	/* it's not really all that important to have a random value, so
+	 * we can do this from the init function, even if there hasn't
+	 * been that much entropy yet */
+	get_random_bytes(&hash_init, sizeof(hash_init));
+
+	netlink_register_notifier(&nfulnl_rtnl_notifier);
+	status = nfnetlink_subsys_register(&nfulnl_subsys);
+	if (status < 0) {
+		printk(KERN_ERR "log: failed to create netlink socket\n");
+		goto cleanup_netlink_notifier;
+	}
+
+#ifdef CONFIG_PROC_FS
+	proc_nful = create_proc_entry("nfnetlink_log", 0440,
+				      proc_net_netfilter);
+	if (!proc_nful)
+		goto cleanup_subsys;
+	proc_nful->proc_fops = &nful_file_ops;
+#endif
+
+	return status;
+
+cleanup:
+	nf_log_unregister_logger(&nfulnl_logger);
+#ifdef CONFIG_PROC_FS
+	remove_proc_entry("nfnetlink_log", proc_net_netfilter);
+cleanup_subsys:
+#endif
+	nfnetlink_subsys_unregister(&nfulnl_subsys);
+cleanup_netlink_notifier:
+	netlink_unregister_notifier(&nfulnl_rtnl_notifier);
+	return status;
+}
+
+static int __init init(void)
+{
+	
+	return init_or_cleanup(1);
+}
+
+static void __exit fini(void)
+{
+	init_or_cleanup(0);
+}
+
+MODULE_DESCRIPTION("netfilter userspace logging");
+MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
+MODULE_LICENSE("GPL");
+
+module_init(init);
+module_exit(fini);

net/netfilter/nfnetlink_queue.c

@@ -1041,6 +1041,7 @@ cleanup:
 	nf_unregister_queue_handlers(nfqnl_enqueue_packet);
 	unregister_netdevice_notifier(&nfqnl_dev_notifier);
 #ifdef CONFIG_PROC_FS
+	remove_proc_entry("nfnetlink_queue", proc_net_netfilter);
 cleanup_subsys:
 #endif	
 	nfnetlink_subsys_unregister(&nfqnl_subsys);