text: /*
   * netfilter module for userspace packet logging daemons
   *
   * (C) 2000-2004 by Harald Welte <laforge@netfilter.org>
   *
   * 2000/09/22 ulog-cprange feature added
   * 2001/01/04 in-kernel queue as proposed by Sebastian Zander 
   * 						<zander@fokus.gmd.de>
   * 2001/01/30 per-rule nlgroup conflicts with global queue. 
   *            nlgroup now global (sysctl)
   * 2001/04/19 ulog-queue reworked, now fixed buffer size specified at
   * 	      module loadtime -HW
   * 2002/07/07 remove broken nflog_rcv() function -HW
   * 2002/08/29 fix shifted/unshifted nlgroup bug -HW
   * 2002/10/30 fix uninitialized mac_len field - <Anders K. Pedersen>
   * 2004/10/25 fix erroneous calculation of 'len' parameter to NLMSG_PUT
   *	      resulting in bogus 'error during NLMSG_PUT' messages.
   *
   * Released under the terms of the GPL
   *
   * This module accepts two parameters: 
   * 
   * nlbufsiz:
   *   The parameter specifies how big the buffer for each netlink multicast
   * group is. e.g. If you say nlbufsiz=8192, up to eight kb of packets will
   * get accumulated in the kernel until they are sent to userspace. It is
   * NOT possible to allocate more than 128kB, and it is strongly discouraged,
   * because atomically allocating 128kB inside the network rx softirq is not
   * reliable. Please also keep in mind that this buffer size is allocated for
   * each nlgroup you are using, so the total kernel memory usage increases
   * by that factor.
   *
   * flushtimeout:
   *   Specify, after how many clock ticks (intel: 100 per second) the queue
   * should be flushed even if it is not full yet.
   *
   * ipt_ULOG.c,v 1.22 2002/10/30 09:07:31 laforge Exp
   */
  
  #include <linux/module.h>
  #include <linux/version.h>
  #include <linux/config.h>
  #include <linux/spinlock.h>
  #include <linux/socket.h>
  #include <linux/skbuff.h>
  #include <linux/kernel.h>
  #include <linux/timer.h>
  #include <linux/netlink.h>
  #include <linux/netdevice.h>
  #include <linux/mm.h>
  #include <linux/socket.h>
  #include <linux/netfilter_ipv4/ip_tables.h>
  #include <linux/netfilter_ipv4/ipt_ULOG.h>
  #include <linux/netfilter_ipv4/lockhelp.h>
  #include <net/sock.h>
  #include <linux/bitops.h>
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
  MODULE_DESCRIPTION("IP tables userspace logging module");
  
  #define ULOG_NL_EVENT		111		/* Harald's favorite number */
  #define ULOG_MAXNLGROUPS	32		/* numer of nlgroups */
  
  #if 0
  #define DEBUGP(format, args...)	printk(__FILE__ ":" __FUNCTION__ ":" \
  				       format, ## args)
  #else
  #define DEBUGP(format, args...)
  #endif
  
  #define PRINTR(format, args...) do { if (net_ratelimit()) printk(format, ## args); } while (0)
  
  static unsigned int nlbufsiz = 4096;
  MODULE_PARM(nlbufsiz, "i");
  MODULE_PARM_DESC(nlbufsiz, "netlink buffer size");
  
  static unsigned int flushtimeout = 10 * HZ;
  MODULE_PARM(flushtimeout, "i");
  MODULE_PARM_DESC(flushtimeout, "buffer flush timeout");
  
  /* global data structures */
  
  typedef struct {
  	unsigned int qlen;		/* number of nlmsgs' in the skb */
  	struct nlmsghdr *lastnlh;	/* netlink header of last msg in skb */
  	struct sk_buff *skb;		/* the pre-allocated skb */
  	struct timer_list timer;	/* the timer function */
  } ulog_buff_t;
  
  static ulog_buff_t ulog_buffers[ULOG_MAXNLGROUPS];	/* array of buffers */
  
  static struct sock *nflognl;	/* our socket */
  DECLARE_LOCK(ulog_lock);	/* spinlock */
  
  /* send one ulog_buff_t to userspace */
  static void ulog_send(unsigned int nlgroupnum)
  {
  	ulog_buff_t *ub = &ulog_buffers[nlgroupnum];
  
  	if (timer_pending(&ub->timer)) {
  		DEBUGP("ipt_ULOG: ulog_send: timer was pending, deleting\n");
  		del_timer(&ub->timer);
  	}
  
  	/* last nlmsg needs NLMSG_DONE */
  	if (ub->qlen > 1)
  		ub->lastnlh->nlmsg_type = NLMSG_DONE;
  
  	NETLINK_CB(ub->skb).dst_groups = (1 << nlgroupnum);
  	DEBUGP("ipt_ULOG: throwing %d packets to netlink mask %u\n",
  		ub->qlen, nlgroupnum);
  	netlink_broadcast(nflognl, ub->skb, 0, (1 << nlgroupnum), GFP_ATOMIC);
  
  	ub->qlen = 0;
  	ub->skb = NULL;
  	ub->lastnlh = NULL;
  
  }
  
  
  /* timer function to flush queue in flushtimeout time */
  static void ulog_timer(unsigned long data)
  {
  	DEBUGP("ipt_ULOG: timer function called, calling ulog_send\n");
  
  	/* lock to protect against somebody modifying our structure
  	 * from ipt_ulog_target at the same time */
  	LOCK_BH(&ulog_lock);
  	ulog_send(data);
  	UNLOCK_BH(&ulog_lock);
  }
  
  struct sk_buff *ulog_alloc_skb(unsigned int size)
  {
  	struct sk_buff *skb;
  
  	/* alloc skb which should be big enough for a whole
  	 * multipart message. WARNING: has to be <= 131000
  	 * due to slab allocator restrictions */
  
  	skb = alloc_skb(nlbufsiz, GFP_ATOMIC);
  	if (!skb) {
  		PRINTR("ipt_ULOG: can't alloc whole buffer %ub!\n",
  			nlbufsiz);
  
  		/* try to allocate only as much as we need for 
  		 * current packet */
  
  		skb = alloc_skb(size, GFP_ATOMIC);
  		if (!skb)
  			PRINTR("ipt_ULOG: can't even allocate %ub\n", size);
  	}
  
  	return skb;
  }
  
  static unsigned int ipt_ulog_target(struct sk_buff **pskb,
  				    unsigned int hooknum,
  				    const struct net_device *in,
  				    const struct net_device *out,
  				    const void *targinfo, void *userinfo)
  {
  	ulog_buff_t *ub;
  	ulog_packet_msg_t *pm;
  	size_t size, copy_len;
  	struct nlmsghdr *nlh;
  	struct ipt_ulog_info *loginfo = (struct ipt_ulog_info *) targinfo;
  
  	/* ffs == find first bit set, necessary because userspace
  	 * is already shifting groupnumber, but we need unshifted.
  	 * ffs() returns [1..32], we need [0..31] */
  	unsigned int groupnum = ffs(loginfo->nl_group) - 1;
  
  	/* calculate the size of the skb needed */
  	if ((loginfo->copy_range == 0) ||
  	    (loginfo->copy_range > (*pskb)->len)) {
  		copy_len = (*pskb)->len;
  	} else {
  		copy_len = loginfo->copy_range;
  	}
  
  	size = NLMSG_SPACE(sizeof(*pm) + copy_len);
  
  	ub = &ulog_buffers[groupnum];
  	
  	LOCK_BH(&ulog_lock);
  
  	if (!ub->skb) {
  		if (!(ub->skb = ulog_alloc_skb(size)))
  			goto alloc_failure;
  	} else if (ub->qlen >= loginfo->qthreshold ||
  		   size > skb_tailroom(ub->skb)) {
  		/* either the queue len is too high or we don't have 
  		 * enough room in nlskb left. send it to userspace. */
  
  		ulog_send(groupnum);
  
  		if (!(ub->skb = ulog_alloc_skb(size)))
  			goto alloc_failure;
  	}
  
  	DEBUGP("ipt_ULOG: qlen %d, qthreshold %d\n", ub->qlen, 
  		loginfo->qthreshold);
  
  	/* NLMSG_PUT contains a hidden goto nlmsg_failure !!! */
  	nlh = NLMSG_PUT(ub->skb, 0, ub->qlen, ULOG_NL_EVENT, 
  			sizeof(*pm)+copy_len);
  	ub->qlen++;
  
  	pm = NLMSG_DATA(nlh);
  
  	/* copy hook, prefix, timestamp, payload, etc. */
  	pm->data_len = copy_len;
  	pm->timestamp_sec = (*pskb)->stamp.tv_sec;
  	pm->timestamp_usec = (*pskb)->stamp.tv_usec;
  	pm->mark = (*pskb)->nfmark;
  	pm->hook = hooknum;
  	if (loginfo->prefix[0] != '\0')
  		strncpy(pm->prefix, loginfo->prefix, sizeof(pm->prefix));
  	else
  		*(pm->prefix) = '\0';
  
  	if (in && in->hard_header_len > 0
  	    && (*pskb)->mac.raw != (void *) (*pskb)->nh.iph
  	    && in->hard_header_len <= ULOG_MAC_LEN) {
  		memcpy(pm->mac, (*pskb)->mac.raw, in->hard_header_len);
  		pm->mac_len = in->hard_header_len;
  	} else
  		pm->mac_len = 0;
  
  	if (in)
  		strncpy(pm->indev_name, in->name, sizeof(pm->indev_name));
  	else
  		pm->indev_name[0] = '\0';
  
  	if (out)
  		strncpy(pm->outdev_name, out->name, sizeof(pm->outdev_name));
  	else
  		pm->outdev_name[0] = '\0';
  
  	if (copy_len)
  		memcpy(pm->payload, (*pskb)->data, copy_len);
  	
  	/* check if we are building multi-part messages */
  	if (ub->qlen > 1) {
  		ub->lastnlh->nlmsg_flags |= NLM_F_MULTI;
  	}
  
  	ub->lastnlh = nlh;
  
  	/* if timer isn't already running, start it */
  	if (!timer_pending(&ub->timer)) {
  		ub->timer.expires = jiffies + flushtimeout;
  		add_timer(&ub->timer);
  	}
  
  	/* if threshold is reached, send message to userspace */
  	if (ub->qlen >= loginfo->qthreshold) {
  		if (loginfo->qthreshold > 1)
  			nlh->nlmsg_type = NLMSG_DONE;
  		ulog_send(groupnum);
  	}
  
  	UNLOCK_BH(&ulog_lock);
  
  	return IPT_CONTINUE;
  
  
  nlmsg_failure:
  	PRINTR("ipt_ULOG: error during NLMSG_PUT\n");
  
  alloc_failure:
  	PRINTR("ipt_ULOG: Error building netlink message\n");
  
  	UNLOCK_BH(&ulog_lock);
  
  	return IPT_CONTINUE;
  }
  
  static int ipt_ulog_checkentry(const char *tablename,
  			       const struct ipt_entry *e,
  			       void *targinfo,
  			       unsigned int targinfosize,
  			       unsigned int hookmask)
  {
  	struct ipt_ulog_info *loginfo = (struct ipt_ulog_info *) targinfo;
  
  	if (targinfosize != IPT_ALIGN(sizeof(struct ipt_ulog_info))) {
  		DEBUGP("ipt_ULOG: targinfosize %u != 0\n", targinfosize);
  		return 0;
  	}
  
  	if (loginfo->prefix[sizeof(loginfo->prefix) - 1] != '\0') {
  		DEBUGP("ipt_ULOG: prefix term %i\n",
  		       loginfo->prefix[sizeof(loginfo->prefix) - 1]);
  		return 0;
  	}
  
  	if (loginfo->qthreshold > ULOG_MAX_QLEN) {
  		DEBUGP("ipt_ULOG: queue threshold %i > MAX_QLEN\n",
  			loginfo->qthreshold);
  		return 0;
  	}
  
  	return 1;
  }
  
  static struct ipt_target ipt_ulog_reg =
      { {NULL, NULL}, "ULOG", ipt_ulog_target, ipt_ulog_checkentry, NULL,
  THIS_MODULE
  };
  
  static int __init init(void)
  {
  	int i;
  
  	DEBUGP("ipt_ULOG: init module\n");
  
  	if (nlbufsiz >= 128*1024) {
  		printk("Netlink buffer has to be <= 128kB\n");
  		return -EINVAL;
  	}
  
  	/* initialize ulog_buffers */
  	for (i = 0; i < ULOG_MAXNLGROUPS; i++) {
  		init_timer(&ulog_buffers[i].timer);
  		ulog_buffers[i].timer.function = ulog_timer;
  		ulog_buffers[i].timer.data = i;
  	}
  
  	nflognl = netlink_kernel_create(NETLINK_NFLOG, NULL);
  	if (!nflognl)
  		return -ENOMEM;
  
  	if (ipt_register_target(&ipt_ulog_reg) != 0) {
  		sock_release(nflognl->socket);
  		return -EINVAL;
  	}
  
  	return 0;
  }
  
  static void __exit fini(void)
  {
  	ulog_buff_t *ub;
  	int i;
  
  	DEBUGP("ipt_ULOG: cleanup_module\n");
  
  	ipt_unregister_target(&ipt_ulog_reg);
  	sock_release(nflognl->socket);
  
  	/* remove pending timers and free allocated skb's */
  	for (i = 0; i < ULOG_MAXNLGROUPS; i++) {
  		ub = &ulog_buffers[i];
  		if (timer_pending(&ub->timer)) {
  			DEBUGP("timer was pending, deleting\n");
  			del_timer(&ub->timer);
  		}
  
  		if (ub->skb) {
  			kfree_skb(ub->skb);
  			ub->skb = NULL;
  		}
  	}
  
  }
  
  module_init(init);
  module_exit(fini);
  