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/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 = NLMSG_GOODSIZE;
  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         if (!ub->skb)
  78                 return;
  79
  80         /* last nlmsg needs NLMSG_DONE */
  81         if (ub->qlen > 1)
  82                 ub->lastnlh->nlmsg_type = NLMSG_DONE;
  83
  84         NETLINK_CB(ub->skb).dst_group = nlgroup + 1;
  85         netlink_broadcast(ebtulognl, ub->skb, 0, nlgroup + 1, GFP_ATOMIC);
  86
  87         ub->qlen = 0;
  88         ub->skb = NULL;
  89 }
  90
  91 /* timer function to flush queue in flushtimeout time */
  92 static void ulog_timer(unsigned long data)
  93 {
  94         spin_lock_bh(&ulog_buffers[data].lock);
  95         if (ulog_buffers[data].skb)
  96                 ulog_send(data);
  97         spin_unlock_bh(&ulog_buffers[data].lock);
  98 }
  99
 100 static struct sk_buff *ulog_alloc_skb(unsigned int size)
 101 {
 102         struct sk_buff *skb;
 103         unsigned int n;
 104
 105         n = max(size, nlbufsiz);
 106         skb = alloc_skb(n, GFP_ATOMIC);
 107         if (!skb) {
 108                 PRINTR(KERN_ERR "ebt_ulog: can't alloc whole buffer "
 109                        "of size %ub!\n", n);
 110                 if (n > size) {
 111                         /* try to allocate only as much as we need for
 112                          * current packet */
 113                         skb = alloc_skb(size, GFP_ATOMIC);
 114                         if (!skb)
 115                                 PRINTR(KERN_ERR "ebt_ulog: can't even allocate "
 116                                        "buffer of size %ub\n", size);
 117                 }
 118         }
 119
 120         return skb;
 121 }
 122
 123 static void ebt_ulog_packet(unsigned int hooknr, const struct sk_buff *skb,
 124    const struct net_device *in, const struct net_device *out,
 125    const struct ebt_ulog_info *uloginfo, const char *prefix)
 126 {
 127         ebt_ulog_packet_msg_t *pm;
 128         size_t size, copy_len;
 129         struct nlmsghdr *nlh;
 130         unsigned int group = uloginfo->nlgroup;
 131         ebt_ulog_buff_t *ub = &ulog_buffers[group];
 132         spinlock_t *lock = &ub->lock;
 133
 134         if ((uloginfo->cprange == 0) ||
 135             (uloginfo->cprange > skb->len + ETH_HLEN))
 136                 copy_len = skb->len + ETH_HLEN;
 137         else
 138                 copy_len = uloginfo->cprange;
 139
 140         size = NLMSG_SPACE(sizeof(*pm) + copy_len);
 141         if (size > nlbufsiz) {
 142                 PRINTR("ebt_ulog: Size %Zd needed, but nlbufsiz=%d\n",
 143                        size, nlbufsiz);
 144                 return;
 145         }
 146
 147         spin_lock_bh(lock);
 148
 149         if (!ub->skb) {
 150                 if (!(ub->skb = ulog_alloc_skb(size)))
 151                         goto alloc_failure;
 152         } else if (size > skb_tailroom(ub->skb)) {
 153                 ulog_send(group);
 154
 155                 if (!(ub->skb = ulog_alloc_skb(size)))
 156                         goto alloc_failure;
 157         }
 158
 159         nlh = NLMSG_PUT(ub->skb, 0, ub->qlen, 0,
 160                         size - NLMSG_ALIGN(sizeof(*nlh)));
 161         ub->qlen++;
 162
 163         pm = NLMSG_DATA(nlh);
 164
 165         /* Fill in the ulog data */
 166         pm->version = EBT_ULOG_VERSION;
 167         do_gettimeofday(&pm->stamp);
 168         if (ub->qlen == 1)
 169                 skb_set_timestamp(ub->skb, &pm->stamp);
 170         pm->data_len = copy_len;
 171         pm->mark = skb->mark;
 172         pm->hook = hooknr;
 173         if (uloginfo->prefix != NULL)
 174                 strcpy(pm->prefix, uloginfo->prefix);
 175         else
 176                 *(pm->prefix) = '\0';
 177
 178         if (in) {
 179                 strcpy(pm->physindev, in->name);
 180                 /* If in isn't a bridge, then physindev==indev */
 181                 if (in->br_port)
 182                         strcpy(pm->indev, in->br_port->br->dev->name);
 183                 else
 184                         strcpy(pm->indev, in->name);
 185         } else
 186                 pm->indev[0] = pm->physindev[0] = '\0';
 187
 188         if (out) {
 189                 /* If out exists, then out is a bridge port */
 190                 strcpy(pm->physoutdev, out->name);
 191                 strcpy(pm->outdev, out->br_port->br->dev->name);
 192         } else
 193                 pm->outdev[0] = pm->physoutdev[0] = '\0';
 194
 195         if (skb_copy_bits(skb, -ETH_HLEN, pm->data, copy_len) < 0)
 196                 BUG();
 197
 198         if (ub->qlen > 1)
 199                 ub->lastnlh->nlmsg_flags |= NLM_F_MULTI;
 200
 201         ub->lastnlh = nlh;
 202
 203         if (ub->qlen >= uloginfo->qthreshold)
 204                 ulog_send(group);
 205         else if (!timer_pending(&ub->timer)) {
 206                 ub->timer.expires = jiffies + flushtimeout * HZ / 100;
 207                 add_timer(&ub->timer);
 208         }
 209
 210 unlock:
 211         spin_unlock_bh(lock);
 212
 213         return;
 214
 215 nlmsg_failure:
 216         printk(KERN_CRIT "ebt_ulog: error during NLMSG_PUT. This should "
 217                "not happen, please report to author.\n");
 218         goto unlock;
 219 alloc_failure:
 220         goto unlock;
 221 }
 222
 223 /* this function is registered with the netfilter core */
 224 static void ebt_log_packet(unsigned int pf, unsigned int hooknum,
 225    const struct sk_buff *skb, const struct net_device *in,
 226    const struct net_device *out, const struct nf_loginfo *li,
 227    const char *prefix)
 228 {
 229         struct ebt_ulog_info loginfo;
 230
 231         if (!li || li->type != NF_LOG_TYPE_ULOG) {
 232                 loginfo.nlgroup = EBT_ULOG_DEFAULT_NLGROUP;
 233                 loginfo.cprange = 0;
 234                 loginfo.qthreshold = EBT_ULOG_DEFAULT_QTHRESHOLD;
 235                 loginfo.prefix[0] = '\0';
 236         } else {
 237                 loginfo.nlgroup = li->u.ulog.group;
 238                 loginfo.cprange = li->u.ulog.copy_len;
 239                 loginfo.qthreshold = li->u.ulog.qthreshold;
 240                 strlcpy(loginfo.prefix, prefix, sizeof(loginfo.prefix));
 241         }
 242
 243         ebt_ulog_packet(hooknum, skb, in, out, &loginfo, prefix);
 244 }
 245
 246 static void ebt_ulog(const struct sk_buff *skb, unsigned int hooknr,
 247    const struct net_device *in, const struct net_device *out,
 248    const void *data, unsigned int datalen)
 249 {
 250         struct ebt_ulog_info *uloginfo = (struct ebt_ulog_info *)data;
 251
 252         ebt_ulog_packet(hooknr, skb, in, out, uloginfo, NULL);
 253 }
 254
 255
 256 static int ebt_ulog_check(const char *tablename, unsigned int hookmask,
 257    const struct ebt_entry *e, void *data, unsigned int datalen)
 258 {
 259         struct ebt_ulog_info *uloginfo = (struct ebt_ulog_info *)data;
 260
 261         if (datalen != EBT_ALIGN(sizeof(struct ebt_ulog_info)) ||
 262             uloginfo->nlgroup > 31)
 263                 return -EINVAL;
 264
 265         uloginfo->prefix[EBT_ULOG_PREFIX_LEN - 1] = '\0';
 266
 267         if (uloginfo->qthreshold > EBT_ULOG_MAX_QLEN)
 268                 uloginfo->qthreshold = EBT_ULOG_MAX_QLEN;
 269
 270         return 0;
 271 }
 272
 273 static struct ebt_watcher ulog = {
 274         .name           = EBT_ULOG_WATCHER,
 275         .watcher        = ebt_ulog,
 276         .check          = ebt_ulog_check,
 277         .me             = THIS_MODULE,
 278 };
 279
 280 static struct nf_logger ebt_ulog_logger = {
 281         .name           = EBT_ULOG_WATCHER,
 282         .logfn          = &ebt_log_packet,
 283         .me             = THIS_MODULE,
 284 };
 285
 286 static int __init ebt_ulog_init(void)
 287 {
 288         int i, ret = 0;
 289
 290         if (nlbufsiz >= 128*1024) {
 291                 printk(KERN_NOTICE "ebt_ulog: Netlink buffer has to be <= 128kB,"
 292                        " please try a smaller nlbufsiz parameter.\n");
 293                 return -EINVAL;
 294         }
 295
 296         /* initialize ulog_buffers */
 297         for (i = 0; i < EBT_ULOG_MAXNLGROUPS; i++) {
 298                 init_timer(&ulog_buffers[i].timer);
 299                 ulog_buffers[i].timer.function = ulog_timer;
 300                 ulog_buffers[i].timer.data = i;
 301                 spin_lock_init(&ulog_buffers[i].lock);
 302         }
 303
 304         ebtulognl = netlink_kernel_create(NETLINK_NFLOG, EBT_ULOG_MAXNLGROUPS,
 305                                           NULL, THIS_MODULE);
 306         if (!ebtulognl)
 307                 ret = -ENOMEM;
 308         else if ((ret = ebt_register_watcher(&ulog)))
 309                 sock_release(ebtulognl->sk_socket);
 310
 311         if (nf_log_register(PF_BRIDGE, &ebt_ulog_logger) < 0) {
 312                 printk(KERN_WARNING "ebt_ulog: not logging via ulog "
 313                        "since somebody else already registered for PF_BRIDGE\n");
 314                 /* we cannot make module load fail here, since otherwise
 315                  * ebtables userspace would abort */
 316         }
 317
 318         return ret;
 319 }
 320
 321 static void __exit ebt_ulog_fini(void)
 322 {
 323         ebt_ulog_buff_t *ub;
 324         int i;
 325
 326         nf_log_unregister(&ebt_ulog_logger);
 327         ebt_unregister_watcher(&ulog);
 328         for (i = 0; i < EBT_ULOG_MAXNLGROUPS; i++) {
 329                 ub = &ulog_buffers[i];
 330                 if (timer_pending(&ub->timer))
 331                         del_timer(&ub->timer);
 332                 spin_lock_bh(&ub->lock);
 333                 if (ub->skb) {
 334                         kfree_skb(ub->skb);
 335                         ub->skb = NULL;
 336                 }
 337                 spin_unlock_bh(&ub->lock);
 338         }
 339         sock_release(ebtulognl->sk_socket);
 340 }
 341
 342 module_init(ebt_ulog_init);
 343 module_exit(ebt_ulog_fini);
 344 MODULE_LICENSE("GPL");
 345 MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>");
 346 MODULE_DESCRIPTION("ebtables userspace logging module for bridged Ethernet"
 347                    " frames");