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/*

 * netfilter module for userspace packet logging daemons

 *

 * (C) 2000-2002 by Harald Welte <laforge@gnumonks.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>

 *

 * 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 */

static size_t qlen;             /* current length of multipart-nlmsg */

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, nlgroup);

        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 ULOG_FLUSH_INTERVAL 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,

                        size - sizeof(*nlh));

        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;

        }

        /* if threshold is reached, send message to userspace */

        if (qlen >= loginfo->qthreshold) {

                if (loginfo->qthreshold > 1)

                        nlh->nlmsg_type = NLMSG_DONE;

        }

        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);

        }

        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);