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