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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  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 <net/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/netns/generic.h>
  45 #include <net/sock.h>
  46 #include "../br_private.h"
  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 int ebt_ulog_net_id __read_mostly;
  67 struct ebt_ulog_net {
  68         unsigned int nlgroup[EBT_ULOG_MAXNLGROUPS];
  69         ebt_ulog_buff_t ulog_buffers[EBT_ULOG_MAXNLGROUPS];
  70         struct sock *ebtulognl;
  71 };
  72
  73 static struct ebt_ulog_net *ebt_ulog_pernet(struct net *net)
  74 {
  75         return net_generic(net, ebt_ulog_net_id);
  76 }
  77
  78 /* send one ulog_buff_t to userspace */
  79 static void ulog_send(struct ebt_ulog_net *ebt, unsigned int nlgroup)
  80 {
  81         ebt_ulog_buff_t *ub = &ebt->ulog_buffers[nlgroup];
  82
  83         del_timer(&ub->timer);
  84
  85         if (!ub->skb)
  86                 return;
  87
  88         /* last nlmsg needs NLMSG_DONE */
  89         if (ub->qlen > 1)
  90                 ub->lastnlh->nlmsg_type = NLMSG_DONE;
  91
  92         NETLINK_CB(ub->skb).dst_group = nlgroup + 1;
  93         netlink_broadcast(ebt->ebtulognl, ub->skb, 0, nlgroup + 1, GFP_ATOMIC);
  94
  95         ub->qlen = 0;
  96         ub->skb = NULL;
  97 }
  98
  99 /* timer function to flush queue in flushtimeout time */
 100 static void ulog_timer(unsigned long data)
 101 {
 102         struct ebt_ulog_net *ebt = container_of((void *)data,
 103                                                 struct ebt_ulog_net,
 104                                                 nlgroup[*(unsigned int *)data]);
 105
 106         ebt_ulog_buff_t *ub = &ebt->ulog_buffers[*(unsigned int *)data];
 107         spin_lock_bh(&ub->lock);
 108         if (ub->skb)
 109                 ulog_send(ebt, *(unsigned int *)data);
 110         spin_unlock_bh(&ub->lock);
 111 }
 112
 113 static struct sk_buff *ulog_alloc_skb(unsigned int size)
 114 {
 115         struct sk_buff *skb;
 116         unsigned int n;
 117
 118         n = max(size, nlbufsiz);
 119         skb = alloc_skb(n, GFP_ATOMIC | __GFP_NOWARN);
 120         if (!skb) {
 121                 if (n > size) {
 122                         /* try to allocate only as much as we need for
 123                          * current packet */
 124                         skb = alloc_skb(size, GFP_ATOMIC);
 125                         if (!skb)
 126                                 pr_debug("cannot even allocate buffer of size %ub\n",
 127                                          size);
 128                 }
 129         }
 130
 131         return skb;
 132 }
 133
 134 static void ebt_ulog_packet(unsigned int hooknr, const struct sk_buff *skb,
 135    const struct net_device *in, const struct net_device *out,
 136    const struct ebt_ulog_info *uloginfo, const char *prefix)
 137 {
 138         ebt_ulog_packet_msg_t *pm;
 139         size_t size, copy_len;
 140         struct nlmsghdr *nlh;
 141         struct net *net = dev_net(in ? in : out);
 142         struct ebt_ulog_net *ebt = ebt_ulog_pernet(net);
 143         unsigned int group = uloginfo->nlgroup;
 144         ebt_ulog_buff_t *ub = &ebt->ulog_buffers[group];
 145         spinlock_t *lock = &ub->lock;
 146         ktime_t kt;
 147
 148         if ((uloginfo->cprange == 0) ||
 149             (uloginfo->cprange > skb->len + ETH_HLEN))
 150                 copy_len = skb->len + ETH_HLEN;
 151         else
 152                 copy_len = uloginfo->cprange;
 153
 154         size = nlmsg_total_size(sizeof(*pm) + copy_len);
 155         if (size > nlbufsiz) {
 156                 pr_debug("Size %Zd needed, but nlbufsiz=%d\n", size, nlbufsiz);
 157                 return;
 158         }
 159
 160         spin_lock_bh(lock);
 161
 162         if (!ub->skb) {
 163                 if (!(ub->skb = ulog_alloc_skb(size)))
 164                         goto unlock;
 165         } else if (size > skb_tailroom(ub->skb)) {
 166                 ulog_send(ebt, group);
 167
 168                 if (!(ub->skb = ulog_alloc_skb(size)))
 169                         goto unlock;
 170         }
 171
 172         nlh = nlmsg_put(ub->skb, 0, ub->qlen, 0,
 173                         size - NLMSG_ALIGN(sizeof(*nlh)), 0);
 174         if (!nlh) {
 175                 kfree_skb(ub->skb);
 176                 ub->skb = NULL;
 177                 goto unlock;
 178         }
 179         ub->qlen++;
 180
 181         pm = nlmsg_data(nlh);
 182
 183         /* Fill in the ulog data */
 184         pm->version = EBT_ULOG_VERSION;
 185         kt = ktime_get_real();
 186         pm->stamp = ktime_to_timeval(kt);
 187         if (ub->qlen == 1)
 188                 ub->skb->tstamp = kt;
 189         pm->data_len = copy_len;
 190         pm->mark = skb->mark;
 191         pm->hook = hooknr;
 192         if (uloginfo->prefix != NULL)
 193                 strcpy(pm->prefix, uloginfo->prefix);
 194         else
 195                 *(pm->prefix) = '\0';
 196
 197         if (in) {
 198                 strcpy(pm->physindev, in->name);
 199                 /* If in isn't a bridge, then physindev==indev */
 200                 if (br_port_exists(in))
 201                         /* rcu_read_lock()ed by nf_hook_slow */
 202                         strcpy(pm->indev, br_port_get_rcu(in)->br->dev->name);
 203                 else
 204                         strcpy(pm->indev, in->name);
 205         } else
 206                 pm->indev[0] = pm->physindev[0] = '\0';
 207
 208         if (out) {
 209                 /* If out exists, then out is a bridge port */
 210                 strcpy(pm->physoutdev, out->name);
 211                 /* rcu_read_lock()ed by nf_hook_slow */
 212                 strcpy(pm->outdev, br_port_get_rcu(out)->br->dev->name);
 213         } else
 214                 pm->outdev[0] = pm->physoutdev[0] = '\0';
 215
 216         if (skb_copy_bits(skb, -ETH_HLEN, pm->data, copy_len) < 0)
 217                 BUG();
 218
 219         if (ub->qlen > 1)
 220                 ub->lastnlh->nlmsg_flags |= NLM_F_MULTI;
 221
 222         ub->lastnlh = nlh;
 223
 224         if (ub->qlen >= uloginfo->qthreshold)
 225                 ulog_send(ebt, group);
 226         else if (!timer_pending(&ub->timer)) {
 227                 ub->timer.expires = jiffies + flushtimeout * HZ / 100;
 228                 add_timer(&ub->timer);
 229         }
 230
 231 unlock:
 232         spin_unlock_bh(lock);
 233 }
 234
 235 /* this function is registered with the netfilter core */
 236 static void ebt_log_packet(u_int8_t pf, unsigned int hooknum,
 237    const struct sk_buff *skb, const struct net_device *in,
 238    const struct net_device *out, const struct nf_loginfo *li,
 239    const char *prefix)
 240 {
 241         struct ebt_ulog_info loginfo;
 242
 243         if (!li || li->type != NF_LOG_TYPE_ULOG) {
 244                 loginfo.nlgroup = EBT_ULOG_DEFAULT_NLGROUP;
 245                 loginfo.cprange = 0;
 246                 loginfo.qthreshold = EBT_ULOG_DEFAULT_QTHRESHOLD;
 247                 loginfo.prefix[0] = '\0';
 248         } else {
 249                 loginfo.nlgroup = li->u.ulog.group;
 250                 loginfo.cprange = li->u.ulog.copy_len;
 251                 loginfo.qthreshold = li->u.ulog.qthreshold;
 252                 strlcpy(loginfo.prefix, prefix, sizeof(loginfo.prefix));
 253         }
 254
 255         ebt_ulog_packet(hooknum, skb, in, out, &loginfo, prefix);
 256 }
 257
 258 static unsigned int
 259 ebt_ulog_tg(struct sk_buff *skb, const struct xt_action_param *par)
 260 {
 261         ebt_ulog_packet(par->hooknum, skb, par->in, par->out,
 262                         par->targinfo, NULL);
 263         return EBT_CONTINUE;
 264 }
 265
 266 static int ebt_ulog_tg_check(const struct xt_tgchk_param *par)
 267 {
 268         struct ebt_ulog_info *uloginfo = par->targinfo;
 269
 270         if (uloginfo->nlgroup > 31)
 271                 return -EINVAL;
 272
 273         uloginfo->prefix[EBT_ULOG_PREFIX_LEN - 1] = '\0';
 274
 275         if (uloginfo->qthreshold > EBT_ULOG_MAX_QLEN)
 276                 uloginfo->qthreshold = EBT_ULOG_MAX_QLEN;
 277
 278         return 0;
 279 }
 280
 281 static struct xt_target ebt_ulog_tg_reg __read_mostly = {
 282         .name           = "ulog",
 283         .revision       = 0,
 284         .family         = NFPROTO_BRIDGE,
 285         .target         = ebt_ulog_tg,
 286         .checkentry     = ebt_ulog_tg_check,
 287         .targetsize     = sizeof(struct ebt_ulog_info),
 288         .me             = THIS_MODULE,
 289 };
 290
 291 static struct nf_logger ebt_ulog_logger __read_mostly = {
 292         .name           = "ebt_ulog",
 293         .logfn          = &ebt_log_packet,
 294         .me             = THIS_MODULE,
 295 };
 296
 297 static int __net_init ebt_ulog_net_init(struct net *net)
 298 {
 299         int i;
 300         struct ebt_ulog_net *ebt = ebt_ulog_pernet(net);
 301
 302         struct netlink_kernel_cfg cfg = {
 303                 .groups = EBT_ULOG_MAXNLGROUPS,
 304         };
 305
 306         /* initialize ulog_buffers */
 307         for (i = 0; i < EBT_ULOG_MAXNLGROUPS; i++) {
 308                 ebt->nlgroup[i] = i;
 309                 setup_timer(&ebt->ulog_buffers[i].timer, ulog_timer,
 310                             (unsigned long)&ebt->nlgroup[i]);
 311                 spin_lock_init(&ebt->ulog_buffers[i].lock);
 312         }
 313
 314         ebt->ebtulognl = netlink_kernel_create(net, NETLINK_NFLOG, &cfg);
 315         if (!ebt->ebtulognl)
 316                 return -ENOMEM;
 317
 318         nf_log_set(net, NFPROTO_BRIDGE, &ebt_ulog_logger);
 319         return 0;
 320 }
 321
 322 static void __net_exit ebt_ulog_net_fini(struct net *net)
 323 {
 324         int i;
 325         struct ebt_ulog_net *ebt = ebt_ulog_pernet(net);
 326
 327         nf_log_unset(net, &ebt_ulog_logger);
 328         for (i = 0; i < EBT_ULOG_MAXNLGROUPS; i++) {
 329                 ebt_ulog_buff_t *ub = &ebt->ulog_buffers[i];
 330                 del_timer(&ub->timer);
 331
 332                 if (ub->skb) {
 333                         kfree_skb(ub->skb);
 334                         ub->skb = NULL;
 335                 }
 336         }
 337         netlink_kernel_release(ebt->ebtulognl);
 338 }
 339
 340 static struct pernet_operations ebt_ulog_net_ops = {
 341         .init = ebt_ulog_net_init,
 342         .exit = ebt_ulog_net_fini,
 343         .id   = &ebt_ulog_net_id,
 344         .size = sizeof(struct ebt_ulog_net),
 345 };
 346
 347 static int __init ebt_ulog_init(void)
 348 {
 349         int ret;
 350
 351         if (nlbufsiz >= 128*1024) {
 352                 pr_warn("Netlink buffer has to be <= 128kB,"
 353                         "please try a smaller nlbufsiz parameter.\n");
 354                 return -EINVAL;
 355         }
 356
 357         ret = register_pernet_subsys(&ebt_ulog_net_ops);
 358         if (ret)
 359                 goto out_pernet;
 360
 361         ret = xt_register_target(&ebt_ulog_tg_reg);
 362         if (ret)
 363                 goto out_target;
 364
 365         nf_log_register(NFPROTO_BRIDGE, &ebt_ulog_logger);
 366
 367         return 0;
 368
 369 out_target:
 370         unregister_pernet_subsys(&ebt_ulog_net_ops);
 371 out_pernet:
 372         return ret;
 373 }
 374
 375 static void __exit ebt_ulog_fini(void)
 376 {
 377         nf_log_unregister(&ebt_ulog_logger);
 378         xt_unregister_target(&ebt_ulog_tg_reg);
 379         unregister_pernet_subsys(&ebt_ulog_net_ops);
 380 }
 381
 382 module_init(ebt_ulog_init);
 383 module_exit(ebt_ulog_fini);
 384 MODULE_LICENSE("GPL");
 385 MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>");
 386 MODULE_DESCRIPTION("Ebtables: Packet logging to netlink using ULOG");