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/sock.h>
  42 #include "../br_private.h"
  43
  44 #define PRINTR(format, args...) do { if (net_ratelimit()) \
  45                                 printk(format , ## args); } while (0)
  46
  47 static unsigned int nlbufsiz = NLMSG_GOODSIZE;
  48 module_param(nlbufsiz, uint, 0600);
  49 MODULE_PARM_DESC(nlbufsiz, "netlink buffer size (number of bytes) "
  50                            "(defaults to 4096)");
  51
  52 static unsigned int flushtimeout = 10;
  53 module_param(flushtimeout, uint, 0600);
  54 MODULE_PARM_DESC(flushtimeout, "buffer flush timeout (hundredths ofa second) "
  55                                "(defaults to 10)");
  56
  57 typedef struct {
  58         unsigned int qlen;              /* number of nlmsgs' in the skb */
  59         struct nlmsghdr *lastnlh;       /* netlink header of last msg in skb */
  60         struct sk_buff *skb;            /* the pre-allocated skb */
  61         struct timer_list timer;        /* the timer function */
  62         spinlock_t lock;                /* the per-queue lock */
  63 } ebt_ulog_buff_t;
  64
  65 static ebt_ulog_buff_t ulog_buffers[EBT_ULOG_MAXNLGROUPS];
  66 static struct sock *ebtulognl;
  67
  68 /* send one ulog_buff_t to userspace */
  69 static void ulog_send(unsigned int nlgroup)
  70 {
  71         ebt_ulog_buff_t *ub = &ulog_buffers[nlgroup];
  72
  73         if (timer_pending(&ub->timer))
  74                 del_timer(&ub->timer);
  75
  76         if (!ub->skb)
  77                 return;
  78
  79         /* last nlmsg needs NLMSG_DONE */
  80         if (ub->qlen > 1)
  81                 ub->lastnlh->nlmsg_type = NLMSG_DONE;
  82
  83         NETLINK_CB(ub->skb).dst_group = nlgroup + 1;
  84         netlink_broadcast(ebtulognl, ub->skb, 0, nlgroup + 1, GFP_ATOMIC);
  85
  86         ub->qlen = 0;
  87         ub->skb = NULL;
  88 }
  89
  90 /* timer function to flush queue in flushtimeout time */
  91 static void ulog_timer(unsigned long data)
  92 {
  93         spin_lock_bh(&ulog_buffers[data].lock);
  94         if (ulog_buffers[data].skb)
  95                 ulog_send(data);
  96         spin_unlock_bh(&ulog_buffers[data].lock);
  97 }
  98
  99 static struct sk_buff *ulog_alloc_skb(unsigned int size)
 100 {
 101         struct sk_buff *skb;
 102         unsigned int n;
 103
 104         n = max(size, nlbufsiz);
 105         skb = alloc_skb(n, GFP_ATOMIC);
 106         if (!skb) {
 107                 PRINTR(KERN_ERR "ebt_ulog: can't alloc whole buffer "
 108                        "of size %ub!\n", n);
 109                 if (n > size) {
 110                         /* try to allocate only as much as we need for
 111                          * current packet */
 112                         skb = alloc_skb(size, GFP_ATOMIC);
 113                         if (!skb)
 114                                 PRINTR(KERN_ERR "ebt_ulog: can't even allocate "
 115                                        "buffer of size %ub\n", size);
 116                 }
 117         }
 118
 119         return skb;
 120 }
 121
 122 static void ebt_ulog_packet(unsigned int hooknr, const struct sk_buff *skb,
 123    const struct net_device *in, const struct net_device *out,
 124    const struct ebt_ulog_info *uloginfo, const char *prefix)
 125 {
 126         ebt_ulog_packet_msg_t *pm;
 127         size_t size, copy_len;
 128         struct nlmsghdr *nlh;
 129         unsigned int group = uloginfo->nlgroup;
 130         ebt_ulog_buff_t *ub = &ulog_buffers[group];
 131         spinlock_t *lock = &ub->lock;
 132         ktime_t kt;
 133
 134         if ((uloginfo->cprange == 0) ||
 135             (uloginfo->cprange > skb->len + ETH_HLEN))
 136                 copy_len = skb->len + ETH_HLEN;
 137         else
 138                 copy_len = uloginfo->cprange;
 139
 140         size = NLMSG_SPACE(sizeof(*pm) + copy_len);
 141         if (size > nlbufsiz) {
 142                 PRINTR("ebt_ulog: Size %Zd needed, but nlbufsiz=%d\n",
 143                        size, nlbufsiz);
 144                 return;
 145         }
 146
 147         spin_lock_bh(lock);
 148
 149         if (!ub->skb) {
 150                 if (!(ub->skb = ulog_alloc_skb(size)))
 151                         goto alloc_failure;
 152         } else if (size > skb_tailroom(ub->skb)) {
 153                 ulog_send(group);
 154
 155                 if (!(ub->skb = ulog_alloc_skb(size)))
 156                         goto alloc_failure;
 157         }
 158
 159         nlh = NLMSG_PUT(ub->skb, 0, ub->qlen, 0,
 160                         size - NLMSG_ALIGN(sizeof(*nlh)));
 161         ub->qlen++;
 162
 163         pm = NLMSG_DATA(nlh);
 164
 165         /* Fill in the ulog data */
 166         pm->version = EBT_ULOG_VERSION;
 167         kt = ktime_get_real();
 168         pm->stamp = ktime_to_timeval(kt);
 169         if (ub->qlen == 1)
 170                 ub->skb->tstamp = kt;
 171         pm->data_len = copy_len;
 172         pm->mark = skb->mark;
 173         pm->hook = hooknr;
 174         if (uloginfo->prefix != NULL)
 175                 strcpy(pm->prefix, uloginfo->prefix);
 176         else
 177                 *(pm->prefix) = '\0';
 178
 179         if (in) {
 180                 strcpy(pm->physindev, in->name);
 181                 /* If in isn't a bridge, then physindev==indev */
 182                 if (in->br_port)
 183                         strcpy(pm->indev, in->br_port->br->dev->name);
 184                 else
 185                         strcpy(pm->indev, in->name);
 186         } else
 187                 pm->indev[0] = pm->physindev[0] = '\0';
 188
 189         if (out) {
 190                 /* If out exists, then out is a bridge port */
 191                 strcpy(pm->physoutdev, out->name);
 192                 strcpy(pm->outdev, out->br_port->br->dev->name);
 193         } else
 194                 pm->outdev[0] = pm->physoutdev[0] = '\0';
 195
 196         if (skb_copy_bits(skb, -ETH_HLEN, pm->data, copy_len) < 0)
 197                 BUG();
 198
 199         if (ub->qlen > 1)
 200                 ub->lastnlh->nlmsg_flags |= NLM_F_MULTI;
 201
 202         ub->lastnlh = nlh;
 203
 204         if (ub->qlen >= uloginfo->qthreshold)
 205                 ulog_send(group);
 206         else if (!timer_pending(&ub->timer)) {
 207                 ub->timer.expires = jiffies + flushtimeout * HZ / 100;
 208                 add_timer(&ub->timer);
 209         }
 210
 211 unlock:
 212         spin_unlock_bh(lock);
 213
 214         return;
 215
 216 nlmsg_failure:
 217         printk(KERN_CRIT "ebt_ulog: error during NLMSG_PUT. This should "
 218                "not happen, please report to author.\n");
 219         goto unlock;
 220 alloc_failure:
 221         goto unlock;
 222 }
 223
 224 /* this function is registered with the netfilter core */
 225 static void ebt_log_packet(unsigned int pf, unsigned int hooknum,
 226    const struct sk_buff *skb, const struct net_device *in,
 227    const struct net_device *out, const struct nf_loginfo *li,
 228    const char *prefix)
 229 {
 230         struct ebt_ulog_info loginfo;
 231
 232         if (!li || li->type != NF_LOG_TYPE_ULOG) {
 233                 loginfo.nlgroup = EBT_ULOG_DEFAULT_NLGROUP;
 234                 loginfo.cprange = 0;
 235                 loginfo.qthreshold = EBT_ULOG_DEFAULT_QTHRESHOLD;
 236                 loginfo.prefix[0] = '\0';
 237         } else {
 238                 loginfo.nlgroup = li->u.ulog.group;
 239                 loginfo.cprange = li->u.ulog.copy_len;
 240                 loginfo.qthreshold = li->u.ulog.qthreshold;
 241                 strlcpy(loginfo.prefix, prefix, sizeof(loginfo.prefix));
 242         }
 243
 244         ebt_ulog_packet(hooknum, skb, in, out, &loginfo, prefix);
 245 }
 246
 247 static void ebt_ulog(const struct sk_buff *skb, unsigned int hooknr,
 248    const struct net_device *in, const struct net_device *out,
 249    const void *data, unsigned int datalen)
 250 {
 251         struct ebt_ulog_info *uloginfo = (struct ebt_ulog_info *)data;
 252
 253         ebt_ulog_packet(hooknr, skb, in, out, uloginfo, NULL);
 254 }
 255
 256
 257 static int ebt_ulog_check(const char *tablename, unsigned int hookmask,
 258    const struct ebt_entry *e, void *data, unsigned int datalen)
 259 {
 260         struct ebt_ulog_info *uloginfo = (struct ebt_ulog_info *)data;
 261
 262         if (datalen != EBT_ALIGN(sizeof(struct ebt_ulog_info)) ||
 263             uloginfo->nlgroup > 31)
 264                 return -EINVAL;
 265
 266         uloginfo->prefix[EBT_ULOG_PREFIX_LEN - 1] = '\0';
 267
 268         if (uloginfo->qthreshold > EBT_ULOG_MAX_QLEN)
 269                 uloginfo->qthreshold = EBT_ULOG_MAX_QLEN;
 270
 271         return 0;
 272 }
 273
 274 static struct ebt_watcher ulog = {
 275         .name           = EBT_ULOG_WATCHER,
 276         .watcher        = ebt_ulog,
 277         .check          = ebt_ulog_check,
 278         .me             = THIS_MODULE,
 279 };
 280
 281 static struct nf_logger ebt_ulog_logger = {
 282         .name           = EBT_ULOG_WATCHER,
 283         .logfn          = &ebt_log_packet,
 284         .me             = THIS_MODULE,
 285 };
 286
 287 static int __init ebt_ulog_init(void)
 288 {
 289         int i, ret = 0;
 290
 291         if (nlbufsiz >= 128*1024) {
 292                 printk(KERN_NOTICE "ebt_ulog: Netlink buffer has to be <= 128kB,"
 293                        " please try a smaller nlbufsiz parameter.\n");
 294                 return -EINVAL;
 295         }
 296
 297         /* initialize ulog_buffers */
 298         for (i = 0; i < EBT_ULOG_MAXNLGROUPS; i++) {
 299                 setup_timer(&ulog_buffers[i].timer, ulog_timer, i);
 300                 spin_lock_init(&ulog_buffers[i].lock);
 301         }
 302
 303         ebtulognl = netlink_kernel_create(&init_net, NETLINK_NFLOG,
 304                                           EBT_ULOG_MAXNLGROUPS, NULL, NULL,
 305                                           THIS_MODULE);
 306         if (!ebtulognl)
 307                 ret = -ENOMEM;
 308         else if ((ret = ebt_register_watcher(&ulog)))
 309                 sock_release(ebtulognl->sk_socket);
 310
 311         if (ret == 0)
 312                 nf_log_register(PF_BRIDGE, &ebt_ulog_logger);
 313
 314         return ret;
 315 }
 316
 317 static void __exit ebt_ulog_fini(void)
 318 {
 319         ebt_ulog_buff_t *ub;
 320         int i;
 321
 322         nf_log_unregister(&ebt_ulog_logger);
 323         ebt_unregister_watcher(&ulog);
 324         for (i = 0; i < EBT_ULOG_MAXNLGROUPS; i++) {
 325                 ub = &ulog_buffers[i];
 326                 if (timer_pending(&ub->timer))
 327                         del_timer(&ub->timer);
 328                 spin_lock_bh(&ub->lock);
 329                 if (ub->skb) {
 330                         kfree_skb(ub->skb);
 331                         ub->skb = NULL;
 332                 }
 333                 spin_unlock_bh(&ub->lock);
 334         }
 335         sock_release(ebtulognl->sk_socket);
 336 }
 337
 338 module_init(ebt_ulog_init);
 339 module_exit(ebt_ulog_fini);
 340 MODULE_LICENSE("GPL");
 341 MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>");
 342 MODULE_DESCRIPTION("ebtables userspace logging module for bridged Ethernet"
 343                    " frames");