text: /*
   * netfilter module for userspace packet logging daemons
   *
   * (C) 2000-2004 by Harald Welte <laforge@netfilter.org>
   * (C) 1999-2001 Paul `Rusty' Russell
   * (C) 2002-2004 Netfilter Core Team <coreteam@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.
   *
   * 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.
   *
   * Actually you should use nlbufsiz a bit smaller than PAGE_SIZE, since
   * nlbufsiz is used with alloc_skb, which adds another
   * sizeof(struct skb_shared_info).  Use NLMSG_GOODSIZE instead.
   *
   * flushtimeout:
   *   Specify, after how many hundredths of a second the queue should be
   *   flushed even if it is not full yet.
   */
  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  #include <linux/module.h>
  #include <linux/spinlock.h>
  #include <linux/socket.h>
  #include <linux/slab.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/moduleparam.h>
  #include <linux/netfilter.h>
  #include <linux/netfilter/x_tables.h>
  #include <linux/netfilter_ipv4/ipt_ULOG.h>
  #include <net/netfilter/nf_log.h>
  #include <net/sock.h>
  #include <linux/bitops.h>
  #include <asm/unaligned.h>
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
  MODULE_DESCRIPTION("Xtables: packet logging to netlink using ULOG");
  MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NFLOG);
  
  #define ULOG_NL_EVENT		111		/* Harald's favorite number */
  #define ULOG_MAXNLGROUPS	32		/* numer of nlgroups */
  
  static unsigned int nlbufsiz = NLMSG_GOODSIZE;
  module_param(nlbufsiz, uint, 0400);
  MODULE_PARM_DESC(nlbufsiz, "netlink buffer size");
  
  static unsigned int flushtimeout = 10;
  module_param(flushtimeout, uint, 0600);
  MODULE_PARM_DESC(flushtimeout, "buffer flush timeout (hundredths of a second)");
  
  static int nflog = 1;
  module_param(nflog, bool, 0400);
  MODULE_PARM_DESC(nflog, "register as internal netfilter logging module");
  
  /* 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 */
  static DEFINE_SPINLOCK(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)) {
  		pr_debug("ulog_send: timer was pending, deleting\n");
  		del_timer(&ub->timer);
  	}
  
  	if (!ub->skb) {
  		pr_debug("ulog_send: nothing to send\n");
  		return;
  	}
  
  	/* last nlmsg needs NLMSG_DONE */
  	if (ub->qlen > 1)
  		ub->lastnlh->nlmsg_type = NLMSG_DONE;
  
  	NETLINK_CB(ub->skb).dst_group = nlgroupnum + 1;
  	pr_debug("throwing %d packets to netlink group %u\n",
  		 ub->qlen, nlgroupnum + 1);
  	netlink_broadcast(nflognl, ub->skb, 0, nlgroupnum + 1, 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)
  {
  	pr_debug("timer function called, calling ulog_send\n");
  
  	/* lock to protect against somebody modifying our structure
  	 * from ipt_ulog_target at the same time */
  	spin_lock_bh(&ulog_lock);
  	ulog_send(data);
  	spin_unlock_bh(&ulog_lock);
  }
  
  static struct sk_buff *ulog_alloc_skb(unsigned int size)
  {
  	struct sk_buff *skb;
  	unsigned int n;
  
  	/* alloc skb which should be big enough for a whole
  	 * multipart message. WARNING: has to be <= 131000
  	 * due to slab allocator restrictions */
  
  	n = max(size, nlbufsiz);
  	skb = alloc_skb(n, GFP_ATOMIC);
  	if (!skb) {
  		pr_debug("cannot alloc whole buffer %ub!\n", n);
  
  		if (n > size) {
  			/* try to allocate only as much as we need for
  			 * current packet */
  
  			skb = alloc_skb(size, GFP_ATOMIC);
  			if (!skb)
  				pr_debug("cannot even allocate %ub\n", size);
  		}
  	}
  
  	return skb;
  }
  
  static void ipt_ulog_packet(unsigned int hooknum,
  			    const struct sk_buff *skb,
  			    const struct net_device *in,
  			    const struct net_device *out,
  			    const struct ipt_ulog_info *loginfo,
  			    const char *prefix)
  {
  	ulog_buff_t *ub;
  	ulog_packet_msg_t *pm;
  	size_t size, copy_len;
  	struct nlmsghdr *nlh;
  	struct timeval tv;
  
  	/* 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 > skb->len)
  		copy_len = skb->len;
  	else
  		copy_len = loginfo->copy_range;
  
  	size = NLMSG_SPACE(sizeof(*pm) + copy_len);
  
  	ub = &ulog_buffers[groupnum];
  
  	spin_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;
  	}
  
  	pr_debug("qlen %d, qthreshold %Zu\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);
  
  	/* We might not have a timestamp, get one */
  	if (skb->tstamp.tv64 == 0)
  		__net_timestamp((struct sk_buff *)skb);
  
  	/* copy hook, prefix, timestamp, payload, etc. */
  	pm->data_len = copy_len;
  	tv = ktime_to_timeval(skb->tstamp);
  	put_unaligned(tv.tv_sec, &pm->timestamp_sec);
  	put_unaligned(tv.tv_usec, &pm->timestamp_usec);
  	put_unaligned(skb->mark, &pm->mark);
  	pm->hook = hooknum;
  	if (prefix != NULL)
  		strncpy(pm->prefix, prefix, sizeof(pm->prefix));
  	else if (loginfo->prefix[0] != '\0')
  		strncpy(pm->prefix, loginfo->prefix, sizeof(pm->prefix));
  	else
  		*(pm->prefix) = '\0';
  
  	if (in && in->hard_header_len > 0 &&
  	    skb->mac_header != skb->network_header &&
  	    in->hard_header_len <= ULOG_MAC_LEN) {
  		memcpy(pm->mac, skb_mac_header(skb), 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';
  
  	/* copy_len <= skb->len, so can't fail. */
  	if (skb_copy_bits(skb, 0, pm->payload, copy_len) < 0)
  		BUG();
  
  	/* 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 * HZ / 100;
  		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);
  	}
  
  	spin_unlock_bh(&ulog_lock);
  
  	return;
  
  nlmsg_failure:
  	pr_debug("error during NLMSG_PUT\n");
  alloc_failure:
  	pr_debug("Error building netlink message\n");
  	spin_unlock_bh(&ulog_lock);
  }
  
  static unsigned int
  ulog_tg(struct sk_buff *skb, const struct xt_action_param *par)
  {
  	ipt_ulog_packet(par->hooknum, skb, par->in, par->out,
  	                par->targinfo, NULL);
  	return XT_CONTINUE;
  }
  
  static void ipt_logfn(u_int8_t pf,
  		      unsigned int hooknum,
  		      const struct sk_buff *skb,
  		      const struct net_device *in,
  		      const struct net_device *out,
  		      const struct nf_loginfo *li,
  		      const char *prefix)
  {
  	struct ipt_ulog_info loginfo;
  
  	if (!li || li->type != NF_LOG_TYPE_ULOG) {
  		loginfo.nl_group = ULOG_DEFAULT_NLGROUP;
  		loginfo.copy_range = 0;
  		loginfo.qthreshold = ULOG_DEFAULT_QTHRESHOLD;
  		loginfo.prefix[0] = '\0';
  	} else {
  		loginfo.nl_group = li->u.ulog.group;
  		loginfo.copy_range = li->u.ulog.copy_len;
  		loginfo.qthreshold = li->u.ulog.qthreshold;
  		strlcpy(loginfo.prefix, prefix, sizeof(loginfo.prefix));
  	}
  
  	ipt_ulog_packet(hooknum, skb, in, out, &loginfo, prefix);
  }
  
  static int ulog_tg_check(const struct xt_tgchk_param *par)
  {
  	const struct ipt_ulog_info *loginfo = par->targinfo;
  
  	if (loginfo->prefix[sizeof(loginfo->prefix) - 1] != '\0') {
  		pr_debug("prefix not null-terminated\n");
  		return -EINVAL;
  	}
  	if (loginfo->qthreshold > ULOG_MAX_QLEN) {
  		pr_debug("queue threshold %Zu > MAX_QLEN\n",
  			 loginfo->qthreshold);
  		return -EINVAL;
  	}
  	return 0;
  }
  
  #ifdef CONFIG_COMPAT
  struct compat_ipt_ulog_info {
  	compat_uint_t	nl_group;
  	compat_size_t	copy_range;
  	compat_size_t	qthreshold;
  	char		prefix[ULOG_PREFIX_LEN];
  };
  
  static void ulog_tg_compat_from_user(void *dst, const void *src)
  {
  	const struct compat_ipt_ulog_info *cl = src;
  	struct ipt_ulog_info l = {
  		.nl_group	= cl->nl_group,
  		.copy_range	= cl->copy_range,
  		.qthreshold	= cl->qthreshold,
  	};
  
  	memcpy(l.prefix, cl->prefix, sizeof(l.prefix));
  	memcpy(dst, &l, sizeof(l));
  }
  
  static int ulog_tg_compat_to_user(void __user *dst, const void *src)
  {
  	const struct ipt_ulog_info *l = src;
  	struct compat_ipt_ulog_info cl = {
  		.nl_group	= l->nl_group,
  		.copy_range	= l->copy_range,
  		.qthreshold	= l->qthreshold,
  	};
  
  	memcpy(cl.prefix, l->prefix, sizeof(cl.prefix));
  	return copy_to_user(dst, &cl, sizeof(cl)) ? -EFAULT : 0;
  }
  #endif /* CONFIG_COMPAT */
  
  static struct xt_target ulog_tg_reg __read_mostly = {
  	.name		= "ULOG",
  	.family		= NFPROTO_IPV4,
  	.target		= ulog_tg,
  	.targetsize	= sizeof(struct ipt_ulog_info),
  	.checkentry	= ulog_tg_check,
  #ifdef CONFIG_COMPAT
  	.compatsize	= sizeof(struct compat_ipt_ulog_info),
  	.compat_from_user = ulog_tg_compat_from_user,
  	.compat_to_user	= ulog_tg_compat_to_user,
  #endif
  	.me		= THIS_MODULE,
  };
  
  static struct nf_logger ipt_ulog_logger __read_mostly = {
  	.name		= "ipt_ULOG",
  	.logfn		= ipt_logfn,
  	.me		= THIS_MODULE,
  };
  
  static int __init ulog_tg_init(void)
  {
  	int ret, i;
  
  	pr_debug("init module\n");
  
  	if (nlbufsiz > 128*1024) {
  		pr_warning("Netlink buffer has to be <= 128kB\n");
  		return -EINVAL;
  	}
  
  	/* initialize ulog_buffers */
  	for (i = 0; i < ULOG_MAXNLGROUPS; i++)
  		setup_timer(&ulog_buffers[i].timer, ulog_timer, i);
  
  	nflognl = netlink_kernel_create(&init_net,
  					NETLINK_NFLOG, ULOG_MAXNLGROUPS, NULL,
  					NULL, THIS_MODULE);
  	if (!nflognl)
  		return -ENOMEM;
  
  	ret = xt_register_target(&ulog_tg_reg);
  	if (ret < 0) {
  		netlink_kernel_release(nflognl);
  		return ret;
  	}
  	if (nflog)
  		nf_log_register(NFPROTO_IPV4, &ipt_ulog_logger);
  
  	return 0;
  }
  
  static void __exit ulog_tg_exit(void)
  {
  	ulog_buff_t *ub;
  	int i;
  
  	pr_debug("cleanup_module\n");
  
  	if (nflog)
  		nf_log_unregister(&ipt_ulog_logger);
  	xt_unregister_target(&ulog_tg_reg);
  	netlink_kernel_release(nflognl);
  
  	/* remove pending timers and free allocated skb's */
  	for (i = 0; i < ULOG_MAXNLGROUPS; i++) {
  		ub = &ulog_buffers[i];
  		if (timer_pending(&ub->timer)) {
  			pr_debug("timer was pending, deleting\n");
  			del_timer(&ub->timer);
  		}
  
  		if (ub->skb) {
  			kfree_skb(ub->skb);
  			ub->skb = NULL;
  		}
  	}
  }
  
  module_init(ulog_tg_init);
  module_exit(ulog_tg_exit);
  