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/netfilter_bridge/ebtables.h>
  40 #include <linux/netfilter_bridge/ebt_ulog.h>
  41 #include <net/netfilter/nf_log.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         ktime_t kt;
 134
 135         if ((uloginfo->cprange == 0) ||
 136             (uloginfo->cprange > skb->len + ETH_HLEN))
 137                 copy_len = skb->len + ETH_HLEN;
 138         else
 139                 copy_len = uloginfo->cprange;
 140
 141         size = NLMSG_SPACE(sizeof(*pm) + copy_len);
 142         if (size > nlbufsiz) {
 143                 PRINTR("ebt_ulog: Size %Zd needed, but nlbufsiz=%d\n",
 144                        size, nlbufsiz);
 145                 return;
 146         }
 147
 148         spin_lock_bh(lock);
 149
 150         if (!ub->skb) {
 151                 if (!(ub->skb = ulog_alloc_skb(size)))
 152                         goto alloc_failure;
 153         } else if (size > skb_tailroom(ub->skb)) {
 154                 ulog_send(group);
 155
 156                 if (!(ub->skb = ulog_alloc_skb(size)))
 157                         goto alloc_failure;
 158         }
 159
 160         nlh = NLMSG_PUT(ub->skb, 0, ub->qlen, 0,
 161                         size - NLMSG_ALIGN(sizeof(*nlh)));
 162         ub->qlen++;
 163
 164         pm = NLMSG_DATA(nlh);
 165
 166         /* Fill in the ulog data */
 167         pm->version = EBT_ULOG_VERSION;
 168         kt = ktime_get_real();
 169         pm->stamp = ktime_to_timeval(kt);
 170         if (ub->qlen == 1)
 171                 ub->skb->tstamp = kt;
 172         pm->data_len = copy_len;
 173         pm->mark = skb->mark;
 174         pm->hook = hooknr;
 175         if (uloginfo->prefix != NULL)
 176                 strcpy(pm->prefix, uloginfo->prefix);
 177         else
 178                 *(pm->prefix) = '\0';
 179
 180         if (in) {
 181                 strcpy(pm->physindev, in->name);
 182                 /* If in isn't a bridge, then physindev==indev */
 183                 if (in->br_port)
 184                         strcpy(pm->indev, in->br_port->br->dev->name);
 185                 else
 186                         strcpy(pm->indev, in->name);
 187         } else
 188                 pm->indev[0] = pm->physindev[0] = '\0';
 189
 190         if (out) {
 191                 /* If out exists, then out is a bridge port */
 192                 strcpy(pm->physoutdev, out->name);
 193                 strcpy(pm->outdev, out->br_port->br->dev->name);
 194         } else
 195                 pm->outdev[0] = pm->physoutdev[0] = '\0';
 196
 197         if (skb_copy_bits(skb, -ETH_HLEN, pm->data, copy_len) < 0)
 198                 BUG();
 199
 200         if (ub->qlen > 1)
 201                 ub->lastnlh->nlmsg_flags |= NLM_F_MULTI;
 202
 203         ub->lastnlh = nlh;
 204
 205         if (ub->qlen >= uloginfo->qthreshold)
 206                 ulog_send(group);
 207         else if (!timer_pending(&ub->timer)) {
 208                 ub->timer.expires = jiffies + flushtimeout * HZ / 100;
 209                 add_timer(&ub->timer);
 210         }
 211
 212 unlock:
 213         spin_unlock_bh(lock);
 214
 215         return;
 216
 217 nlmsg_failure:
 218         printk(KERN_CRIT "ebt_ulog: error during NLMSG_PUT. This should "
 219                "not happen, please report to author.\n");
 220         goto unlock;
 221 alloc_failure:
 222         goto unlock;
 223 }
 224
 225 /* this function is registered with the netfilter core */
 226 static void ebt_log_packet(unsigned int pf, unsigned int hooknum,
 227    const struct sk_buff *skb, const struct net_device *in,
 228    const struct net_device *out, const struct nf_loginfo *li,
 229    const char *prefix)
 230 {
 231         struct ebt_ulog_info loginfo;
 232
 233         if (!li || li->type != NF_LOG_TYPE_ULOG) {
 234                 loginfo.nlgroup = EBT_ULOG_DEFAULT_NLGROUP;
 235                 loginfo.cprange = 0;
 236                 loginfo.qthreshold = EBT_ULOG_DEFAULT_QTHRESHOLD;
 237                 loginfo.prefix[0] = '\0';
 238         } else {
 239                 loginfo.nlgroup = li->u.ulog.group;
 240                 loginfo.cprange = li->u.ulog.copy_len;
 241                 loginfo.qthreshold = li->u.ulog.qthreshold;
 242                 strlcpy(loginfo.prefix, prefix, sizeof(loginfo.prefix));
 243         }
 244
 245         ebt_ulog_packet(hooknum, skb, in, out, &loginfo, prefix);
 246 }
 247
 248 static void ebt_ulog(const struct sk_buff *skb, unsigned int hooknr,
 249    const struct net_device *in, const struct net_device *out,
 250    const void *data, unsigned int datalen)
 251 {
 252         const struct ebt_ulog_info *uloginfo = data;
 253
 254         ebt_ulog_packet(hooknr, skb, in, out, uloginfo, NULL);
 255 }
 256
 257
 258 static int ebt_ulog_check(const char *tablename, unsigned int hookmask,
 259    const struct ebt_entry *e, void *data, unsigned int datalen)
 260 {
 261         struct ebt_ulog_info *uloginfo = data;
 262
 263         if (datalen != EBT_ALIGN(sizeof(struct ebt_ulog_info)) ||
 264             uloginfo->nlgroup > 31)
 265                 return -EINVAL;
 266
 267         uloginfo->prefix[EBT_ULOG_PREFIX_LEN - 1] = '\0';
 268
 269         if (uloginfo->qthreshold > EBT_ULOG_MAX_QLEN)
 270                 uloginfo->qthreshold = EBT_ULOG_MAX_QLEN;
 271
 272         return 0;
 273 }
 274
 275 static struct ebt_watcher ulog __read_mostly = {
 276         .name           = EBT_ULOG_WATCHER,
 277         .watcher        = ebt_ulog,
 278         .check          = ebt_ulog_check,
 279         .me             = THIS_MODULE,
 280 };
 281
 282 static const struct nf_logger ebt_ulog_logger = {
 283         .name           = EBT_ULOG_WATCHER,
 284         .logfn          = &ebt_log_packet,
 285         .me             = THIS_MODULE,
 286 };
 287
 288 static int __init ebt_ulog_init(void)
 289 {
 290         int i, ret = 0;
 291
 292         if (nlbufsiz >= 128*1024) {
 293                 printk(KERN_NOTICE "ebt_ulog: Netlink buffer has to be <= 128kB,"
 294                        " please try a smaller nlbufsiz parameter.\n");
 295                 return -EINVAL;
 296         }
 297
 298         /* initialize ulog_buffers */
 299         for (i = 0; i < EBT_ULOG_MAXNLGROUPS; i++) {
 300                 setup_timer(&ulog_buffers[i].timer, ulog_timer, i);
 301                 spin_lock_init(&ulog_buffers[i].lock);
 302         }
 303
 304         ebtulognl = netlink_kernel_create(&init_net, NETLINK_NFLOG,
 305                                           EBT_ULOG_MAXNLGROUPS, NULL, NULL,
 306                                           THIS_MODULE);
 307         if (!ebtulognl)
 308                 ret = -ENOMEM;
 309         else if ((ret = ebt_register_watcher(&ulog)))
 310                 netlink_kernel_release(ebtulognl);
 311
 312         if (ret == 0)
 313                 nf_log_register(PF_BRIDGE, &ebt_ulog_logger);
 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(&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         netlink_kernel_release(ebtulognl);
 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: Packet logging to netlink using ULOG");