net/bridge/netfilter/ebt_ulog.c

   1 /*
   2  * netfilter module for userspace bridged Ethernet frames logging daemons
   3  *
   4  *      Authors:
   5  *      Bart De Schuymer <bdschuym@pandora.be>
   6  *
   7  *  November, 2004
   8  *
   9  * Based on ipt_ULOG.c, which is
  10  * (C) 2000-2002 by Harald Welte <laforge@netfilter.org>
  11  *
  12  * This module accepts two parameters:
  13  *
  14  * nlbufsiz:
  15  *   The parameter specifies how big the buffer for each netlink multicast
  16  * group is. e.g. If you say nlbufsiz=8192, up to eight kb of packets will
  17  * get accumulated in the kernel until they are sent to userspace. It is
  18  * NOT possible to allocate more than 128kB, and it is strongly discouraged,
  19  * because atomically allocating 128kB inside the network rx softirq is not
  20  * reliable. Please also keep in mind that this buffer size is allocated for
  21  * each nlgroup you are using, so the total kernel memory usage increases
  22  * by that factor.
  23  *
  24  * flushtimeout:
  25  *   Specify, after how many hundredths of a second the queue should be
  26  *   flushed even if it is not full yet.
  27  *
  28  */
  29
  30 #include <linux/module.h>
  31 #include <linux/config.h>
  32 #include <linux/spinlock.h>
  33 #include <linux/socket.h>
  34 #include <linux/skbuff.h>
  35 #include <linux/kernel.h>
  36 #include <linux/timer.h>
  37 #include <linux/netlink.h>
  38 #include <linux/netdevice.h>
  39 #include <linux/module.h>
  40 #include <linux/netfilter_bridge/ebtables.h>
  41 #include <linux/netfilter_bridge/ebt_ulog.h>
  42 #include <net/sock.h>
  43 #include "../br_private.h"
  44
  45 #define PRINTR(format, args...) do { if (net_ratelimit()) \
  46                                 printk(format , ## args); } while (0)
  47
  48 static unsigned int nlbufsiz = 4096;
  49 module_param(nlbufsiz, uint, 0600);
  50 MODULE_PARM_DESC(nlbufsiz, "netlink buffer size (number of bytes) "
  51                            "(defaults to 4096)");
  52
  53 static unsigned int flushtimeout = 10;
  54 module_param(flushtimeout, uint, 0600);
  55 MODULE_PARM_DESC(flushtimeout, "buffer flush timeout (hundredths ofa second) "
  56                                "(defaults to 10)");
  57
  58 typedef struct {
  59         unsigned int qlen;              /* number of nlmsgs' in the skb */
  60         struct nlmsghdr *lastnlh;       /* netlink header of last msg in skb */
  61         struct sk_buff *skb;            /* the pre-allocated skb */
  62         struct timer_list timer;        /* the timer function */
  63         spinlock_t lock;                /* the per-queue lock */
  64 } ebt_ulog_buff_t;
  65
  66 static ebt_ulog_buff_t ulog_buffers[EBT_ULOG_MAXNLGROUPS];
  67 static struct sock *ebtulognl;
  68
  69 /* send one ulog_buff_t to userspace */
  70 static void ulog_send(unsigned int nlgroup)
  71 {
  72         ebt_ulog_buff_t *ub = &ulog_buffers[nlgroup];
  73
  74         if (timer_pending(&ub->timer))
  75                 del_timer(&ub->timer);
  76
  77         /* last nlmsg needs NLMSG_DONE */
  78         if (ub->qlen > 1)
  79                 ub->lastnlh->nlmsg_type = NLMSG_DONE;
  80
  81         NETLINK_CB(ub->skb).dst_group = nlgroup + 1;
  82         netlink_broadcast(ebtulognl, ub->skb, 0, nlgroup + 1, GFP_ATOMIC);
  83
  84         ub->qlen = 0;
  85         ub->skb = NULL;
  86 }
  87
  88 /* timer function to flush queue in flushtimeout time */
  89 static void ulog_timer(unsigned long data)
  90 {
  91         spin_lock_bh(&ulog_buffers[data].lock);
  92         if (ulog_buffers[data].skb)
  93                 ulog_send(data);
  94         spin_unlock_bh(&ulog_buffers[data].lock);
  95 }
  96
  97 static struct sk_buff *ulog_alloc_skb(unsigned int size)
  98 {
  99         struct sk_buff *skb;
 100
 101         skb = alloc_skb(nlbufsiz, GFP_ATOMIC);
 102         if (!skb) {
 103                 PRINTR(KERN_ERR "ebt_ulog: can't alloc whole buffer "
 104                        "of size %ub!\n", nlbufsiz);
 105                 if (size < nlbufsiz) {
 106                         /* try to allocate only as much as we need for
 107                          * current packet */
 108                         skb = alloc_skb(size, GFP_ATOMIC);
 109                         if (!skb)
 110                                 PRINTR(KERN_ERR "ebt_ulog: can't even allocate "
 111                                        "buffer of size %ub\n", size);
 112                 }
 113         }
 114
 115         return skb;
 116 }
 117
 118 static void ebt_ulog(const struct sk_buff *skb, unsigned int hooknr,
 119    const struct net_device *in, const struct net_device *out,
 120    const void *data, unsigned int datalen)
 121 {
 122         ebt_ulog_packet_msg_t *pm;
 123         size_t size, copy_len;
 124         struct nlmsghdr *nlh;
 125         struct ebt_ulog_info *uloginfo = (struct ebt_ulog_info *)data;
 126         unsigned int group = uloginfo->nlgroup;
 127         ebt_ulog_buff_t *ub = &ulog_buffers[group];
 128         spinlock_t *lock = &ub->lock;
 129
 130         if ((uloginfo->cprange == 0) ||
 131             (uloginfo->cprange > skb->len + ETH_HLEN))
 132                 copy_len = skb->len + ETH_HLEN;
 133         else
 134                 copy_len = uloginfo->cprange;
 135
 136         size = NLMSG_SPACE(sizeof(*pm) + copy_len);
 137         if (size > nlbufsiz) {
 138                 PRINTR("ebt_ulog: Size %Zd needed, but nlbufsiz=%d\n",
 139                        size, nlbufsiz);
 140                 return;
 141         }
 142
 143         spin_lock_bh(lock);
 144
 145         if (!ub->skb) {
 146                 if (!(ub->skb = ulog_alloc_skb(size)))
 147                         goto alloc_failure;
 148         } else if (size > skb_tailroom(ub->skb)) {
 149                 ulog_send(group);
 150
 151                 if (!(ub->skb = ulog_alloc_skb(size)))
 152                         goto alloc_failure;
 153         }
 154
 155         nlh = NLMSG_PUT(ub->skb, 0, ub->qlen, 0,
 156                         size - NLMSG_ALIGN(sizeof(*nlh)));
 157         ub->qlen++;
 158
 159         pm = NLMSG_DATA(nlh);
 160
 161         /* Fill in the ulog data */
 162         pm->version = EBT_ULOG_VERSION;
 163         do_gettimeofday(&pm->stamp);
 164         if (ub->qlen == 1)
 165                 skb_set_timestamp(ub->skb, &pm->stamp);
 166         pm->data_len = copy_len;
 167         pm->mark = skb->nfmark;
 168         pm->hook = hooknr;
 169         if (uloginfo->prefix != NULL)
 170                 strcpy(pm->prefix, uloginfo->prefix);
 171         else
 172                 *(pm->prefix) = '\0';
 173
 174         if (in) {
 175                 strcpy(pm->physindev, in->name);
 176                 /* If in isn't a bridge, then physindev==indev */
 177                 if (in->br_port)
 178                         strcpy(pm->indev, in->br_port->br->dev->name);
 179                 else
 180                         strcpy(pm->indev, in->name);
 181         } else
 182                 pm->indev[0] = pm->physindev[0] = '\0';
 183
 184         if (out) {
 185                 /* If out exists, then out is a bridge port */
 186                 strcpy(pm->physoutdev, out->name);
 187                 strcpy(pm->outdev, out->br_port->br->dev->name);
 188         } else
 189                 pm->outdev[0] = pm->physoutdev[0] = '\0';
 190
 191         if (skb_copy_bits(skb, -ETH_HLEN, pm->data, copy_len) < 0)
 192                 BUG();
 193
 194         if (ub->qlen > 1)
 195                 ub->lastnlh->nlmsg_flags |= NLM_F_MULTI;
 196
 197         ub->lastnlh = nlh;
 198
 199         if (ub->qlen >= uloginfo->qthreshold)
 200                 ulog_send(group);
 201         else if (!timer_pending(&ub->timer)) {
 202                 ub->timer.expires = jiffies + flushtimeout * HZ / 100;
 203                 add_timer(&ub->timer);
 204         }
 205
 206 unlock:
 207         spin_unlock_bh(lock);
 208
 209         return;
 210
 211 nlmsg_failure:
 212         printk(KERN_CRIT "ebt_ulog: error during NLMSG_PUT. This should "
 213                "not happen, please report to author.\n");
 214         goto unlock;
 215 alloc_failure:
 216         goto unlock;
 217 }
 218
 219 static int ebt_ulog_check(const char *tablename, unsigned int hookmask,
 220    const struct ebt_entry *e, void *data, unsigned int datalen)
 221 {
 222         struct ebt_ulog_info *uloginfo = (struct ebt_ulog_info *)data;
 223
 224         if (datalen != EBT_ALIGN(sizeof(struct ebt_ulog_info)) ||
 225             uloginfo->nlgroup > 31)
 226                 return -EINVAL;
 227
 228         uloginfo->prefix[EBT_ULOG_PREFIX_LEN - 1] = '\0';
 229
 230         if (uloginfo->qthreshold > EBT_ULOG_MAX_QLEN)
 231                 uloginfo->qthreshold = EBT_ULOG_MAX_QLEN;
 232
 233         return 0;
 234 }
 235
 236 static struct ebt_watcher ulog = {
 237         .name           = EBT_ULOG_WATCHER,
 238         .watcher        = ebt_ulog,
 239         .check          = ebt_ulog_check,
 240         .me             = THIS_MODULE,
 241 };
 242
 243 static int __init init(void)
 244 {
 245         int i, ret = 0;
 246
 247         if (nlbufsiz >= 128*1024) {
 248                 printk(KERN_NOTICE "ebt_ulog: Netlink buffer has to be <= 128kB,"
 249                        " please try a smaller nlbufsiz parameter.\n");
 250                 return -EINVAL;
 251         }
 252
 253         /* initialize ulog_buffers */
 254         for (i = 0; i < EBT_ULOG_MAXNLGROUPS; i++) {
 255                 init_timer(&ulog_buffers[i].timer);
 256                 ulog_buffers[i].timer.function = ulog_timer;
 257                 ulog_buffers[i].timer.data = i;
 258                 spin_lock_init(&ulog_buffers[i].lock);
 259         }
 260
 261         ebtulognl = netlink_kernel_create(NETLINK_NFLOG, EBT_ULOG_MAXNLGROUPS,
 262                                           NULL, THIS_MODULE);
 263         if (!ebtulognl)
 264                 ret = -ENOMEM;
 265         else if ((ret = ebt_register_watcher(&ulog)))
 266                 sock_release(ebtulognl->sk_socket);
 267
 268         return ret;
 269 }
 270
 271 static void __exit fini(void)
 272 {
 273         ebt_ulog_buff_t *ub;
 274         int i;
 275
 276         ebt_unregister_watcher(&ulog);
 277         for (i = 0; i < EBT_ULOG_MAXNLGROUPS; i++) {
 278                 ub = &ulog_buffers[i];
 279                 if (timer_pending(&ub->timer))
 280                         del_timer(&ub->timer);
 281                 spin_lock_bh(&ub->lock);
 282                 if (ub->skb) {
 283                         kfree_skb(ub->skb);
 284                         ub->skb = NULL;
 285                 }
 286                 spin_unlock_bh(&ub->lock);
 287         }
 288         sock_release(ebtulognl->sk_socket);
 289 }
 290
 291 module_init(init);
 292 module_exit(fini);
 293 MODULE_LICENSE("GPL");
 294 MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>");
 295 MODULE_DESCRIPTION("ebtables userspace logging module for bridged Ethernet"
 296                    " frames");