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  *      Harald Welte <laforge@netfilter.org>
   7  *
   8  *  November, 2004
   9  *
  10  * Based on ipt_ULOG.c, which is
  11  * (C) 2000-2002 by Harald Welte <laforge@netfilter.org>
  12  *
  13  * This module accepts two parameters:
  14  *
  15  * nlbufsiz:
  16  *   The parameter specifies how big the buffer for each netlink multicast
  17  * group is. e.g. If you say nlbufsiz=8192, up to eight kb of packets will
  18  * get accumulated in the kernel until they are sent to userspace. It is
  19  * NOT possible to allocate more than 128kB, and it is strongly discouraged,
  20  * because atomically allocating 128kB inside the network rx softirq is not
  21  * reliable. Please also keep in mind that this buffer size is allocated for
  22  * each nlgroup you are using, so the total kernel memory usage increases
  23  * by that factor.
  24  *
  25  * flushtimeout:
  26  *   Specify, after how many hundredths of a second the queue should be
  27  *   flushed even if it is not full yet.
  28  *
  29  */
  30
  31 #include <linux/module.h>
  32 #include <linux/config.h>
  33 #include <linux/spinlock.h>
  34 #include <linux/socket.h>
  35 #include <linux/skbuff.h>
  36 #include <linux/kernel.h>
  37 #include <linux/timer.h>
  38 #include <linux/netlink.h>
  39 #include <linux/netdevice.h>
  40 #include <linux/module.h>
  41 #include <linux/netfilter_bridge/ebtables.h>
  42 #include <linux/netfilter_bridge/ebt_ulog.h>
  43 #include <net/sock.h>
  44 #include "../br_private.h"
  45
  46 #define PRINTR(format, args...) do { if (net_ratelimit()) \
  47                                 printk(format , ## args); } while (0)
  48
  49 static unsigned int nlbufsiz = NLMSG_GOODSIZE;
  50 module_param(nlbufsiz, uint, 0600);
  51 MODULE_PARM_DESC(nlbufsiz, "netlink buffer size (number of bytes) "
  52                            "(defaults to 4096)");
  53
  54 static unsigned int flushtimeout = 10;
  55 module_param(flushtimeout, uint, 0600);
  56 MODULE_PARM_DESC(flushtimeout, "buffer flush timeout (hundredths ofa second) "
  57                                "(defaults to 10)");
  58
  59 typedef struct {
  60         unsigned int qlen;              /* number of nlmsgs' in the skb */
  61         struct nlmsghdr *lastnlh;       /* netlink header of last msg in skb */
  62         struct sk_buff *skb;            /* the pre-allocated skb */
  63         struct timer_list timer;        /* the timer function */
  64         spinlock_t lock;                /* the per-queue lock */
  65 } ebt_ulog_buff_t;
  66
  67 static ebt_ulog_buff_t ulog_buffers[EBT_ULOG_MAXNLGROUPS];
  68 static struct sock *ebtulognl;
  69
  70 /* send one ulog_buff_t to userspace */
  71 static void ulog_send(unsigned int nlgroup)
  72 {
  73         ebt_ulog_buff_t *ub = &ulog_buffers[nlgroup];
  74
  75         if (timer_pending(&ub->timer))
  76                 del_timer(&ub->timer);
  77
  78         /* last nlmsg needs NLMSG_DONE */
  79         if (ub->qlen > 1)
  80                 ub->lastnlh->nlmsg_type = NLMSG_DONE;
  81
  82         NETLINK_CB(ub->skb).dst_group = nlgroup + 1;
  83         netlink_broadcast(ebtulognl, ub->skb, 0, nlgroup + 1, GFP_ATOMIC);
  84
  85         ub->qlen = 0;
  86         ub->skb = NULL;
  87 }
  88
  89 /* timer function to flush queue in flushtimeout time */
  90 static void ulog_timer(unsigned long data)
  91 {
  92         spin_lock_bh(&ulog_buffers[data].lock);
  93         if (ulog_buffers[data].skb)
  94                 ulog_send(data);
  95         spin_unlock_bh(&ulog_buffers[data].lock);
  96 }
  97
  98 static struct sk_buff *ulog_alloc_skb(unsigned int size)
  99 {
 100         struct sk_buff *skb;
 101         unsigned int n;
 102
 103         n = max(size, nlbufsiz);
 104         skb = alloc_skb(n, GFP_ATOMIC);
 105         if (!skb) {
 106                 PRINTR(KERN_ERR "ebt_ulog: can't alloc whole buffer "
 107                        "of size %ub!\n", n);
 108                 if (n > size) {
 109                         /* try to allocate only as much as we need for
 110                          * current packet */
 111                         skb = alloc_skb(size, GFP_ATOMIC);
 112                         if (!skb)
 113                                 PRINTR(KERN_ERR "ebt_ulog: can't even allocate "
 114                                        "buffer of size %ub\n", size);
 115                 }
 116         }
 117
 118         return skb;
 119 }
 120
 121 static void ebt_ulog_packet(unsigned int hooknr, const struct sk_buff *skb,
 122    const struct net_device *in, const struct net_device *out,
 123    const struct ebt_ulog_info *uloginfo, const char *prefix)
 124 {
 125         ebt_ulog_packet_msg_t *pm;
 126         size_t size, copy_len;
 127         struct nlmsghdr *nlh;
 128         unsigned int group = uloginfo->nlgroup;
 129         ebt_ulog_buff_t *ub = &ulog_buffers[group];
 130         spinlock_t *lock = &ub->lock;
 131
 132         if ((uloginfo->cprange == 0) ||
 133             (uloginfo->cprange > skb->len + ETH_HLEN))
 134                 copy_len = skb->len + ETH_HLEN;
 135         else
 136                 copy_len = uloginfo->cprange;
 137
 138         size = NLMSG_SPACE(sizeof(*pm) + copy_len);
 139         if (size > nlbufsiz) {
 140                 PRINTR("ebt_ulog: Size %Zd needed, but nlbufsiz=%d\n",
 141                        size, nlbufsiz);
 142                 return;
 143         }
 144
 145         spin_lock_bh(lock);
 146
 147         if (!ub->skb) {
 148                 if (!(ub->skb = ulog_alloc_skb(size)))
 149                         goto alloc_failure;
 150         } else if (size > skb_tailroom(ub->skb)) {
 151                 ulog_send(group);
 152
 153                 if (!(ub->skb = ulog_alloc_skb(size)))
 154                         goto alloc_failure;
 155         }
 156
 157         nlh = NLMSG_PUT(ub->skb, 0, ub->qlen, 0,
 158                         size - NLMSG_ALIGN(sizeof(*nlh)));
 159         ub->qlen++;
 160
 161         pm = NLMSG_DATA(nlh);
 162
 163         /* Fill in the ulog data */
 164         pm->version = EBT_ULOG_VERSION;
 165         do_gettimeofday(&pm->stamp);
 166         if (ub->qlen == 1)
 167                 skb_set_timestamp(ub->skb, &pm->stamp);
 168         pm->data_len = copy_len;
 169         pm->mark = skb->nfmark;
 170         pm->hook = hooknr;
 171         if (uloginfo->prefix != NULL)
 172                 strcpy(pm->prefix, uloginfo->prefix);
 173         else
 174                 *(pm->prefix) = '\0';
 175
 176         if (in) {
 177                 strcpy(pm->physindev, in->name);
 178                 /* If in isn't a bridge, then physindev==indev */
 179                 if (in->br_port)
 180                         strcpy(pm->indev, in->br_port->br->dev->name);
 181                 else
 182                         strcpy(pm->indev, in->name);
 183         } else
 184                 pm->indev[0] = pm->physindev[0] = '\0';
 185
 186         if (out) {
 187                 /* If out exists, then out is a bridge port */
 188                 strcpy(pm->physoutdev, out->name);
 189                 strcpy(pm->outdev, out->br_port->br->dev->name);
 190         } else
 191                 pm->outdev[0] = pm->physoutdev[0] = '\0';
 192
 193         if (skb_copy_bits(skb, -ETH_HLEN, pm->data, copy_len) < 0)
 194                 BUG();
 195
 196         if (ub->qlen > 1)
 197                 ub->lastnlh->nlmsg_flags |= NLM_F_MULTI;
 198
 199         ub->lastnlh = nlh;
 200
 201         if (ub->qlen >= uloginfo->qthreshold)
 202                 ulog_send(group);
 203         else if (!timer_pending(&ub->timer)) {
 204                 ub->timer.expires = jiffies + flushtimeout * HZ / 100;
 205                 add_timer(&ub->timer);
 206         }
 207
 208 unlock:
 209         spin_unlock_bh(lock);
 210
 211         return;
 212
 213 nlmsg_failure:
 214         printk(KERN_CRIT "ebt_ulog: error during NLMSG_PUT. This should "
 215                "not happen, please report to author.\n");
 216         goto unlock;
 217 alloc_failure:
 218         goto unlock;
 219 }
 220
 221 /* this function is registered with the netfilter core */
 222 static void ebt_log_packet(unsigned int pf, unsigned int hooknum,
 223    const struct sk_buff *skb, const struct net_device *in,
 224    const struct net_device *out, const struct nf_loginfo *li,
 225    const char *prefix)
 226 {
 227         struct ebt_ulog_info loginfo;
 228
 229         if (!li || li->type != NF_LOG_TYPE_ULOG) {
 230                 loginfo.nlgroup = EBT_ULOG_DEFAULT_NLGROUP;
 231                 loginfo.cprange = 0;
 232                 loginfo.qthreshold = EBT_ULOG_DEFAULT_QTHRESHOLD;
 233                 loginfo.prefix[0] = '\0';
 234         } else {
 235                 loginfo.nlgroup = li->u.ulog.group;
 236                 loginfo.cprange = li->u.ulog.copy_len;
 237                 loginfo.qthreshold = li->u.ulog.qthreshold;
 238                 strlcpy(loginfo.prefix, prefix, sizeof(loginfo.prefix));
 239         }
 240
 241         ebt_ulog_packet(hooknum, skb, in, out, &loginfo, prefix);
 242 }
 243
 244 static void ebt_ulog(const struct sk_buff *skb, unsigned int hooknr,
 245    const struct net_device *in, const struct net_device *out,
 246    const void *data, unsigned int datalen)
 247 {
 248         struct ebt_ulog_info *uloginfo = (struct ebt_ulog_info *)data;
 249
 250         ebt_ulog_packet(hooknr, skb, in, out, uloginfo, NULL);
 251 }
 252
 253
 254 static int ebt_ulog_check(const char *tablename, unsigned int hookmask,
 255    const struct ebt_entry *e, void *data, unsigned int datalen)
 256 {
 257         struct ebt_ulog_info *uloginfo = (struct ebt_ulog_info *)data;
 258
 259         if (datalen != EBT_ALIGN(sizeof(struct ebt_ulog_info)) ||
 260             uloginfo->nlgroup > 31)
 261                 return -EINVAL;
 262
 263         uloginfo->prefix[EBT_ULOG_PREFIX_LEN - 1] = '\0';
 264
 265         if (uloginfo->qthreshold > EBT_ULOG_MAX_QLEN)
 266                 uloginfo->qthreshold = EBT_ULOG_MAX_QLEN;
 267
 268         return 0;
 269 }
 270
 271 static struct ebt_watcher ulog = {
 272         .name           = EBT_ULOG_WATCHER,
 273         .watcher        = ebt_ulog,
 274         .check          = ebt_ulog_check,
 275         .me             = THIS_MODULE,
 276 };
 277
 278 static struct nf_logger ebt_ulog_logger = {
 279         .name           = EBT_ULOG_WATCHER,
 280         .logfn          = &ebt_log_packet,
 281         .me             = THIS_MODULE,
 282 };
 283
 284 static int __init init(void)
 285 {
 286         int i, ret = 0;
 287
 288         if (nlbufsiz >= 128*1024) {
 289                 printk(KERN_NOTICE "ebt_ulog: Netlink buffer has to be <= 128kB,"
 290                        " please try a smaller nlbufsiz parameter.\n");
 291                 return -EINVAL;
 292         }
 293
 294         /* initialize ulog_buffers */
 295         for (i = 0; i < EBT_ULOG_MAXNLGROUPS; i++) {
 296                 init_timer(&ulog_buffers[i].timer);
 297                 ulog_buffers[i].timer.function = ulog_timer;
 298                 ulog_buffers[i].timer.data = i;
 299                 spin_lock_init(&ulog_buffers[i].lock);
 300         }
 301
 302         ebtulognl = netlink_kernel_create(NETLINK_NFLOG, EBT_ULOG_MAXNLGROUPS,
 303                                           NULL, THIS_MODULE);
 304         if (!ebtulognl)
 305                 ret = -ENOMEM;
 306         else if ((ret = ebt_register_watcher(&ulog)))
 307                 sock_release(ebtulognl->sk_socket);
 308
 309         if (nf_log_register(PF_BRIDGE, &ebt_ulog_logger) < 0) {
 310                 printk(KERN_WARNING "ebt_ulog: not logging via ulog "
 311                        "since somebody else already registered for PF_BRIDGE\n");
 312                 /* we cannot make module load fail here, since otherwise
 313                  * ebtables userspace would abort */
 314         }
 315
 316         return ret;
 317 }
 318
 319 static void __exit fini(void)
 320 {
 321         ebt_ulog_buff_t *ub;
 322         int i;
 323
 324         nf_log_unregister_logger(&ebt_ulog_logger);
 325         ebt_unregister_watcher(&ulog);
 326         for (i = 0; i < EBT_ULOG_MAXNLGROUPS; i++) {
 327                 ub = &ulog_buffers[i];
 328                 if (timer_pending(&ub->timer))
 329                         del_timer(&ub->timer);
 330                 spin_lock_bh(&ub->lock);
 331                 if (ub->skb) {
 332                         kfree_skb(ub->skb);
 333                         ub->skb = NULL;
 334                 }
 335                 spin_unlock_bh(&ub->lock);
 336         }
 337         sock_release(ebtulognl->sk_socket);
 338 }
 339
 340 module_init(init);
 341 module_exit(fini);
 342 MODULE_LICENSE("GPL");
 343 MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>");
 344 MODULE_DESCRIPTION("ebtables userspace logging module for bridged Ethernet"
 345                    " frames");