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/slab.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/netfilter/x_tables.h>
  41 #include <linux/netfilter_bridge/ebtables.h>
  42 #include <linux/netfilter_bridge/ebt_ulog.h>
  43 #include <net/netfilter/nf_log.h>
  44 #include <net/sock.h>
  45 #include "../br_private.h"
  46
  47 #define PRINTR(format, args...) do { if (net_ratelimit()) \
  48                                 printk(format , ## args); } while (0)
  49
  50 static unsigned int nlbufsiz = NLMSG_GOODSIZE;
  51 module_param(nlbufsiz, uint, 0600);
  52 MODULE_PARM_DESC(nlbufsiz, "netlink buffer size (number of bytes) "
  53                            "(defaults to 4096)");
  54
  55 static unsigned int flushtimeout = 10;
  56 module_param(flushtimeout, uint, 0600);
  57 MODULE_PARM_DESC(flushtimeout, "buffer flush timeout (hundredths ofa second) "
  58                                "(defaults to 10)");
  59
  60 typedef struct {
  61         unsigned int qlen;              /* number of nlmsgs' in the skb */
  62         struct nlmsghdr *lastnlh;       /* netlink header of last msg in skb */
  63         struct sk_buff *skb;            /* the pre-allocated skb */
  64         struct timer_list timer;        /* the timer function */
  65         spinlock_t lock;                /* the per-queue lock */
  66 } ebt_ulog_buff_t;
  67
  68 static ebt_ulog_buff_t ulog_buffers[EBT_ULOG_MAXNLGROUPS];
  69 static struct sock *ebtulognl;
  70
  71 /* send one ulog_buff_t to userspace */
  72 static void ulog_send(unsigned int nlgroup)
  73 {
  74         ebt_ulog_buff_t *ub = &ulog_buffers[nlgroup];
  75
  76         if (timer_pending(&ub->timer))
  77                 del_timer(&ub->timer);
  78
  79         if (!ub->skb)
  80                 return;
  81
  82         /* last nlmsg needs NLMSG_DONE */
  83         if (ub->qlen > 1)
  84                 ub->lastnlh->nlmsg_type = NLMSG_DONE;
  85
  86         NETLINK_CB(ub->skb).dst_group = nlgroup + 1;
  87         netlink_broadcast(ebtulognl, ub->skb, 0, nlgroup + 1, GFP_ATOMIC);
  88
  89         ub->qlen = 0;
  90         ub->skb = NULL;
  91 }
  92
  93 /* timer function to flush queue in flushtimeout time */
  94 static void ulog_timer(unsigned long data)
  95 {
  96         spin_lock_bh(&ulog_buffers[data].lock);
  97         if (ulog_buffers[data].skb)
  98                 ulog_send(data);
  99         spin_unlock_bh(&ulog_buffers[data].lock);
 100 }
 101
 102 static struct sk_buff *ulog_alloc_skb(unsigned int size)
 103 {
 104         struct sk_buff *skb;
 105         unsigned int n;
 106
 107         n = max(size, nlbufsiz);
 108         skb = alloc_skb(n, GFP_ATOMIC);
 109         if (!skb) {
 110                 PRINTR(KERN_ERR "ebt_ulog: can't alloc whole buffer "
 111                        "of size %ub!\n", n);
 112                 if (n > size) {
 113                         /* try to allocate only as much as we need for
 114                          * current packet */
 115                         skb = alloc_skb(size, GFP_ATOMIC);
 116                         if (!skb)
 117                                 PRINTR(KERN_ERR "ebt_ulog: can't even allocate "
 118                                        "buffer of size %ub\n", size);
 119                 }
 120         }
 121
 122         return skb;
 123 }
 124
 125 static void ebt_ulog_packet(unsigned int hooknr, const struct sk_buff *skb,
 126    const struct net_device *in, const struct net_device *out,
 127    const struct ebt_ulog_info *uloginfo, const char *prefix)
 128 {
 129         ebt_ulog_packet_msg_t *pm;
 130         size_t size, copy_len;
 131         struct nlmsghdr *nlh;
 132         unsigned int group = uloginfo->nlgroup;
 133         ebt_ulog_buff_t *ub = &ulog_buffers[group];
 134         spinlock_t *lock = &ub->lock;
 135         ktime_t kt;
 136
 137         if ((uloginfo->cprange == 0) ||
 138             (uloginfo->cprange > skb->len + ETH_HLEN))
 139                 copy_len = skb->len + ETH_HLEN;
 140         else
 141                 copy_len = uloginfo->cprange;
 142
 143         size = NLMSG_SPACE(sizeof(*pm) + copy_len);
 144         if (size > nlbufsiz) {
 145                 PRINTR("ebt_ulog: Size %Zd needed, but nlbufsiz=%d\n",
 146                        size, nlbufsiz);
 147                 return;
 148         }
 149
 150         spin_lock_bh(lock);
 151
 152         if (!ub->skb) {
 153                 if (!(ub->skb = ulog_alloc_skb(size)))
 154                         goto alloc_failure;
 155         } else if (size > skb_tailroom(ub->skb)) {
 156                 ulog_send(group);
 157
 158                 if (!(ub->skb = ulog_alloc_skb(size)))
 159                         goto alloc_failure;
 160         }
 161
 162         nlh = NLMSG_PUT(ub->skb, 0, ub->qlen, 0,
 163                         size - NLMSG_ALIGN(sizeof(*nlh)));
 164         ub->qlen++;
 165
 166         pm = NLMSG_DATA(nlh);
 167
 168         /* Fill in the ulog data */
 169         pm->version = EBT_ULOG_VERSION;
 170         kt = ktime_get_real();
 171         pm->stamp = ktime_to_timeval(kt);
 172         if (ub->qlen == 1)
 173                 ub->skb->tstamp = kt;
 174         pm->data_len = copy_len;
 175         pm->mark = skb->mark;
 176         pm->hook = hooknr;
 177         if (uloginfo->prefix != NULL)
 178                 strcpy(pm->prefix, uloginfo->prefix);
 179         else
 180                 *(pm->prefix) = '\0';
 181
 182         if (in) {
 183                 strcpy(pm->physindev, in->name);
 184                 /* If in isn't a bridge, then physindev==indev */
 185                 if (in->br_port)
 186                         strcpy(pm->indev, in->br_port->br->dev->name);
 187                 else
 188                         strcpy(pm->indev, in->name);
 189         } else
 190                 pm->indev[0] = pm->physindev[0] = '\0';
 191
 192         if (out) {
 193                 /* If out exists, then out is a bridge port */
 194                 strcpy(pm->physoutdev, out->name);
 195                 strcpy(pm->outdev, out->br_port->br->dev->name);
 196         } else
 197                 pm->outdev[0] = pm->physoutdev[0] = '\0';
 198
 199         if (skb_copy_bits(skb, -ETH_HLEN, pm->data, copy_len) < 0)
 200                 BUG();
 201
 202         if (ub->qlen > 1)
 203                 ub->lastnlh->nlmsg_flags |= NLM_F_MULTI;
 204
 205         ub->lastnlh = nlh;
 206
 207         if (ub->qlen >= uloginfo->qthreshold)
 208                 ulog_send(group);
 209         else if (!timer_pending(&ub->timer)) {
 210                 ub->timer.expires = jiffies + flushtimeout * HZ / 100;
 211                 add_timer(&ub->timer);
 212         }
 213
 214 unlock:
 215         spin_unlock_bh(lock);
 216
 217         return;
 218
 219 nlmsg_failure:
 220         printk(KERN_CRIT "ebt_ulog: error during NLMSG_PUT. This should "
 221                "not happen, please report to author.\n");
 222         goto unlock;
 223 alloc_failure:
 224         goto unlock;
 225 }
 226
 227 /* this function is registered with the netfilter core */
 228 static void ebt_log_packet(u_int8_t pf, unsigned int hooknum,
 229    const struct sk_buff *skb, const struct net_device *in,
 230    const struct net_device *out, const struct nf_loginfo *li,
 231    const char *prefix)
 232 {
 233         struct ebt_ulog_info loginfo;
 234
 235         if (!li || li->type != NF_LOG_TYPE_ULOG) {
 236                 loginfo.nlgroup = EBT_ULOG_DEFAULT_NLGROUP;
 237                 loginfo.cprange = 0;
 238                 loginfo.qthreshold = EBT_ULOG_DEFAULT_QTHRESHOLD;
 239                 loginfo.prefix[0] = '\0';
 240         } else {
 241                 loginfo.nlgroup = li->u.ulog.group;
 242                 loginfo.cprange = li->u.ulog.copy_len;
 243                 loginfo.qthreshold = li->u.ulog.qthreshold;
 244                 strlcpy(loginfo.prefix, prefix, sizeof(loginfo.prefix));
 245         }
 246
 247         ebt_ulog_packet(hooknum, skb, in, out, &loginfo, prefix);
 248 }
 249
 250 static unsigned int
 251 ebt_ulog_tg(struct sk_buff *skb, const struct xt_target_param *par)
 252 {
 253         ebt_ulog_packet(par->hooknum, skb, par->in, par->out,
 254                         par->targinfo, NULL);
 255         return EBT_CONTINUE;
 256 }
 257
 258 static bool ebt_ulog_tg_check(const struct xt_tgchk_param *par)
 259 {
 260         struct ebt_ulog_info *uloginfo = par->targinfo;
 261
 262         if (uloginfo->nlgroup > 31)
 263                 return false;
 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 true;
 271 }
 272
 273 static struct xt_target ebt_ulog_tg_reg __read_mostly = {
 274         .name           = "ulog",
 275         .revision       = 0,
 276         .family         = NFPROTO_BRIDGE,
 277         .target         = ebt_ulog_tg,
 278         .checkentry     = ebt_ulog_tg_check,
 279         .targetsize     = sizeof(struct ebt_ulog_info),
 280         .me             = THIS_MODULE,
 281 };
 282
 283 static struct nf_logger ebt_ulog_logger __read_mostly = {
 284         .name           = "ebt_ulog",
 285         .logfn          = &ebt_log_packet,
 286         .me             = THIS_MODULE,
 287 };
 288
 289 static int __init ebt_ulog_init(void)
 290 {
 291         int ret;
 292         int i;
 293
 294         if (nlbufsiz >= 128*1024) {
 295                 printk(KERN_NOTICE "ebt_ulog: Netlink buffer has to be <= 128kB,"
 296                        " please try a smaller nlbufsiz parameter.\n");
 297                 return -EINVAL;
 298         }
 299
 300         /* initialize ulog_buffers */
 301         for (i = 0; i < EBT_ULOG_MAXNLGROUPS; i++) {
 302                 setup_timer(&ulog_buffers[i].timer, ulog_timer, i);
 303                 spin_lock_init(&ulog_buffers[i].lock);
 304         }
 305
 306         ebtulognl = netlink_kernel_create(&init_net, NETLINK_NFLOG,
 307                                           EBT_ULOG_MAXNLGROUPS, NULL, NULL,
 308                                           THIS_MODULE);
 309         if (!ebtulognl) {
 310                 printk(KERN_WARNING KBUILD_MODNAME ": out of memory trying to "
 311                        "call netlink_kernel_create\n");
 312                 ret = -ENOMEM;
 313         } else if ((ret = xt_register_target(&ebt_ulog_tg_reg)) != 0) {
 314                 netlink_kernel_release(ebtulognl);
 315         }
 316
 317         if (ret == 0)
 318                 nf_log_register(NFPROTO_BRIDGE, &ebt_ulog_logger);
 319
 320         return ret;
 321 }
 322
 323 static void __exit ebt_ulog_fini(void)
 324 {
 325         ebt_ulog_buff_t *ub;
 326         int i;
 327
 328         nf_log_unregister(&ebt_ulog_logger);
 329         xt_unregister_target(&ebt_ulog_tg_reg);
 330         for (i = 0; i < EBT_ULOG_MAXNLGROUPS; i++) {
 331                 ub = &ulog_buffers[i];
 332                 if (timer_pending(&ub->timer))
 333                         del_timer(&ub->timer);
 334                 spin_lock_bh(&ub->lock);
 335                 if (ub->skb) {
 336                         kfree_skb(ub->skb);
 337                         ub->skb = NULL;
 338                 }
 339                 spin_unlock_bh(&ub->lock);
 340         }
 341         netlink_kernel_release(ebtulognl);
 342 }
 343
 344 module_init(ebt_ulog_init);
 345 module_exit(ebt_ulog_fini);
 346 MODULE_LICENSE("GPL");
 347 MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>");
 348 MODULE_DESCRIPTION("Ebtables: Packet logging to netlink using ULOG");