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/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/x_tables.h>
  40 #include <linux/netfilter_bridge/ebtables.h>
  41 #include <linux/netfilter_bridge/ebt_ulog.h>
  42 #include <net/netfilter/nf_log.h>
  43 #include <net/sock.h>
  44 #include "../br_private.h"
  45
  46 static unsigned int nlbufsiz = NLMSG_GOODSIZE;
  47 module_param(nlbufsiz, uint, 0600);
  48 MODULE_PARM_DESC(nlbufsiz, "netlink buffer size (number of bytes) "
  49                            "(defaults to 4096)");
  50
  51 static unsigned int flushtimeout = 10;
  52 module_param(flushtimeout, uint, 0600);
  53 MODULE_PARM_DESC(flushtimeout, "buffer flush timeout (hundredths ofa second) "
  54                                "(defaults to 10)");
  55
  56 typedef struct {
  57         unsigned int qlen;              /* number of nlmsgs' in the skb */
  58         struct nlmsghdr *lastnlh;       /* netlink header of last msg in skb */
  59         struct sk_buff *skb;            /* the pre-allocated skb */
  60         struct timer_list timer;        /* the timer function */
  61         spinlock_t lock;                /* the per-queue lock */
  62 } ebt_ulog_buff_t;
  63
  64 static ebt_ulog_buff_t ulog_buffers[EBT_ULOG_MAXNLGROUPS];
  65 static struct sock *ebtulognl;
  66
  67 /* send one ulog_buff_t to userspace */
  68 static void ulog_send(unsigned int nlgroup)
  69 {
  70         ebt_ulog_buff_t *ub = &ulog_buffers[nlgroup];
  71
  72         if (timer_pending(&ub->timer))
  73                 del_timer(&ub->timer);
  74
  75         if (!ub->skb)
  76                 return;
  77
  78         /* last nlmsg needs NLMSG_DONE */
  79         if (ub->qlen > 1)
  80                 ub->lastnlh->nlmsg_type = NLMSG_DONE;
  81
  82         NETLINK_CB(ub->skb).dst_group = nlgroup + 1;
  83         netlink_broadcast(ebtulognl, ub->skb, 0, nlgroup + 1, GFP_ATOMIC);
  84
  85         ub->qlen = 0;
  86         ub->skb = NULL;
  87 }
  88
  89 /* timer function to flush queue in flushtimeout time */
  90 static void ulog_timer(unsigned long data)
  91 {
  92         spin_lock_bh(&ulog_buffers[data].lock);
  93         if (ulog_buffers[data].skb)
  94                 ulog_send(data);
  95         spin_unlock_bh(&ulog_buffers[data].lock);
  96 }
  97
  98 static struct sk_buff *ulog_alloc_skb(unsigned int size)
  99 {
 100         struct sk_buff *skb;
 101         unsigned int n;
 102
 103         n = max(size, nlbufsiz);
 104         skb = alloc_skb(n, GFP_ATOMIC);
 105         if (!skb) {
 106                 pr_debug("cannot alloc whole buffer 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                                 pr_debug("cannot 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         ktime_t kt;
 131
 132         if ((uloginfo->cprange == 0) ||
 133             (uloginfo->cprange > skb->len + ETH_HLEN))
 134                 copy_len = skb->len + ETH_HLEN;
 135         else
 136                 copy_len = uloginfo->cprange;
 137
 138         size = NLMSG_SPACE(sizeof(*pm) + copy_len);
 139         if (size > nlbufsiz) {
 140                 pr_debug("Size %Zd needed, but nlbufsiz=%d\n", 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         kt = ktime_get_real();
 165         pm->stamp = ktime_to_timeval(kt);
 166         if (ub->qlen == 1)
 167                 ub->skb->tstamp = kt;
 168         pm->data_len = copy_len;
 169         pm->mark = skb->mark;
 170         pm->hook = hooknr;
 171         if (uloginfo->prefix != NULL)
 172                 strcpy(pm->prefix, uloginfo->prefix);
 173         else
 174                 *(pm->prefix) = '\0';
 175
 176         if (in) {
 177                 strcpy(pm->physindev, in->name);
 178                 /* If in isn't a bridge, then physindev==indev */
 179                 if (in->br_port)
 180                         strcpy(pm->indev, in->br_port->br->dev->name);
 181                 else
 182                         strcpy(pm->indev, in->name);
 183         } else
 184                 pm->indev[0] = pm->physindev[0] = '\0';
 185
 186         if (out) {
 187                 /* If out exists, then out is a bridge port */
 188                 strcpy(pm->physoutdev, out->name);
 189                 strcpy(pm->outdev, out->br_port->br->dev->name);
 190         } else
 191                 pm->outdev[0] = pm->physoutdev[0] = '\0';
 192
 193         if (skb_copy_bits(skb, -ETH_HLEN, pm->data, copy_len) < 0)
 194                 BUG();
 195
 196         if (ub->qlen > 1)
 197                 ub->lastnlh->nlmsg_flags |= NLM_F_MULTI;
 198
 199         ub->lastnlh = nlh;
 200
 201         if (ub->qlen >= uloginfo->qthreshold)
 202                 ulog_send(group);
 203         else if (!timer_pending(&ub->timer)) {
 204                 ub->timer.expires = jiffies + flushtimeout * HZ / 100;
 205                 add_timer(&ub->timer);
 206         }
 207
 208 unlock:
 209         spin_unlock_bh(lock);
 210
 211         return;
 212
 213 nlmsg_failure:
 214         pr_debug("error during NLMSG_PUT. This should "
 215                  "not happen, please report to author.\n");
 216         goto unlock;
 217 alloc_failure:
 218         goto unlock;
 219 }
 220
 221 /* this function is registered with the netfilter core */
 222 static void ebt_log_packet(u_int8_t pf, unsigned int hooknum,
 223    const struct sk_buff *skb, const struct net_device *in,
 224    const struct net_device *out, const struct nf_loginfo *li,
 225    const char *prefix)
 226 {
 227         struct ebt_ulog_info loginfo;
 228
 229         if (!li || li->type != NF_LOG_TYPE_ULOG) {
 230                 loginfo.nlgroup = EBT_ULOG_DEFAULT_NLGROUP;
 231                 loginfo.cprange = 0;
 232                 loginfo.qthreshold = EBT_ULOG_DEFAULT_QTHRESHOLD;
 233                 loginfo.prefix[0] = '\0';
 234         } else {
 235                 loginfo.nlgroup = li->u.ulog.group;
 236                 loginfo.cprange = li->u.ulog.copy_len;
 237                 loginfo.qthreshold = li->u.ulog.qthreshold;
 238                 strlcpy(loginfo.prefix, prefix, sizeof(loginfo.prefix));
 239         }
 240
 241         ebt_ulog_packet(hooknum, skb, in, out, &loginfo, prefix);
 242 }
 243
 244 static unsigned int
 245 ebt_ulog_tg(struct sk_buff *skb, const struct xt_target_param *par)
 246 {
 247         ebt_ulog_packet(par->hooknum, skb, par->in, par->out,
 248                         par->targinfo, NULL);
 249         return EBT_CONTINUE;
 250 }
 251
 252 static int ebt_ulog_tg_check(const struct xt_tgchk_param *par)
 253 {
 254         struct ebt_ulog_info *uloginfo = par->targinfo;
 255
 256         if (uloginfo->nlgroup > 31)
 257                 return false;
 258
 259         uloginfo->prefix[EBT_ULOG_PREFIX_LEN - 1] = '\0';
 260
 261         if (uloginfo->qthreshold > EBT_ULOG_MAX_QLEN)
 262                 uloginfo->qthreshold = EBT_ULOG_MAX_QLEN;
 263
 264         return true;
 265 }
 266
 267 static struct xt_target ebt_ulog_tg_reg __read_mostly = {
 268         .name           = "ulog",
 269         .revision       = 0,
 270         .family         = NFPROTO_BRIDGE,
 271         .target         = ebt_ulog_tg,
 272         .checkentry     = ebt_ulog_tg_check,
 273         .targetsize     = sizeof(struct ebt_ulog_info),
 274         .me             = THIS_MODULE,
 275 };
 276
 277 static struct nf_logger ebt_ulog_logger __read_mostly = {
 278         .name           = "ebt_ulog",
 279         .logfn          = &ebt_log_packet,
 280         .me             = THIS_MODULE,
 281 };
 282
 283 static int __init ebt_ulog_init(void)
 284 {
 285         int ret;
 286         int i;
 287
 288         if (nlbufsiz >= 128*1024) {
 289                 pr_warning("Netlink buffer has to be <= 128kB,"
 290                            " please try a smaller nlbufsiz parameter.\n");
 291                 return -EINVAL;
 292         }
 293
 294         /* initialize ulog_buffers */
 295         for (i = 0; i < EBT_ULOG_MAXNLGROUPS; i++) {
 296                 setup_timer(&ulog_buffers[i].timer, ulog_timer, i);
 297                 spin_lock_init(&ulog_buffers[i].lock);
 298         }
 299
 300         ebtulognl = netlink_kernel_create(&init_net, NETLINK_NFLOG,
 301                                           EBT_ULOG_MAXNLGROUPS, NULL, NULL,
 302                                           THIS_MODULE);
 303         if (!ebtulognl)
 304                 ret = -ENOMEM;
 305         else if ((ret = xt_register_target(&ebt_ulog_tg_reg)) != 0)
 306                 netlink_kernel_release(ebtulognl);
 307
 308         if (ret == 0)
 309                 nf_log_register(NFPROTO_BRIDGE, &ebt_ulog_logger);
 310
 311         return ret;
 312 }
 313
 314 static void __exit ebt_ulog_fini(void)
 315 {
 316         ebt_ulog_buff_t *ub;
 317         int i;
 318
 319         nf_log_unregister(&ebt_ulog_logger);
 320         xt_unregister_target(&ebt_ulog_tg_reg);
 321         for (i = 0; i < EBT_ULOG_MAXNLGROUPS; i++) {
 322                 ub = &ulog_buffers[i];
 323                 if (timer_pending(&ub->timer))
 324                         del_timer(&ub->timer);
 325                 spin_lock_bh(&ub->lock);
 326                 if (ub->skb) {
 327                         kfree_skb(ub->skb);
 328                         ub->skb = NULL;
 329                 }
 330                 spin_unlock_bh(&ub->lock);
 331         }
 332         netlink_kernel_release(ebtulognl);
 333 }
 334
 335 module_init(ebt_ulog_init);
 336 module_exit(ebt_ulog_fini);
 337 MODULE_LICENSE("GPL");
 338 MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>");
 339 MODULE_DESCRIPTION("Ebtables: Packet logging to netlink using ULOG");