release/src-rt-6.x/linux/linux-2.6/net/ipv4/netfilter/ipt_ULOG.c

   1 /*
   2  * netfilter module for userspace packet logging daemons
   3  *
   4  * (C) 2000-2004 by Harald Welte <laforge@netfilter.org>
   5  * (C) 1999-2001 Paul `Rusty' Russell
   6  * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  *
  12  * This module accepts two parameters:
  13  *
  14  * nlbufsiz:
  15  *   The parameter specifies how big the buffer for each netlink multicast
  16  * group is. e.g. If you say nlbufsiz=8192, up to eight kb of packets will
  17  * get accumulated in the kernel until they are sent to userspace. It is
  18  * NOT possible to allocate more than 128kB, and it is strongly discouraged,
  19  * because atomically allocating 128kB inside the network rx softirq is not
  20  * reliable. Please also keep in mind that this buffer size is allocated for
  21  * each nlgroup you are using, so the total kernel memory usage increases
  22  * by that factor.
  23  *
  24  * Actually you should use nlbufsiz a bit smaller than PAGE_SIZE, since
  25  * nlbufsiz is used with alloc_skb, which adds another
  26  * sizeof(struct skb_shared_info).  Use NLMSG_GOODSIZE instead.
  27  *
  28  * flushtimeout:
  29  *   Specify, after how many hundredths of a second the queue should be
  30  *   flushed even if it is not full yet.
  31  */
  32
  33 #include <linux/module.h>
  34 #include <linux/spinlock.h>
  35 #include <linux/socket.h>
  36 #include <linux/skbuff.h>
  37 #include <linux/kernel.h>
  38 #include <linux/timer.h>
  39 #include <linux/netlink.h>
  40 #include <linux/netdevice.h>
  41 #include <linux/mm.h>
  42 #include <linux/moduleparam.h>
  43 #include <linux/netfilter.h>
  44 #include <linux/netfilter/x_tables.h>
  45 #include <linux/netfilter_ipv4/ipt_ULOG.h>
  46 #include <net/sock.h>
  47 #include <linux/bitops.h>
  48 #include <asm/unaligned.h>
  49
  50 MODULE_LICENSE("GPL");
  51 MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
  52 MODULE_DESCRIPTION("iptables userspace logging module");
  53 MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NFLOG);
  54
  55 #define ULOG_NL_EVENT           111             /* Harald's favorite number */
  56 #define ULOG_MAXNLGROUPS        32              /* numer of nlgroups */
  57
  58 #if 0
  59 #define DEBUGP(format, args...) printk("%s:%s:" format, \
  60                                        __FILE__, __FUNCTION__ , ## args)
  61 #else
  62 #define DEBUGP(format, args...)
  63 #endif
  64
  65 #define PRINTR(format, args...) do { if (net_ratelimit()) printk(format , ## args); } while (0)
  66
  67 static unsigned int nlbufsiz = NLMSG_GOODSIZE;
  68 module_param(nlbufsiz, uint, 0400);
  69 MODULE_PARM_DESC(nlbufsiz, "netlink buffer size");
  70
  71 static unsigned int flushtimeout = 10;
  72 module_param(flushtimeout, uint, 0600);
  73 MODULE_PARM_DESC(flushtimeout, "buffer flush timeout (hundredths of a second)");
  74
  75 static int nflog = 1;
  76 module_param(nflog, bool, 0400);
  77 MODULE_PARM_DESC(nflog, "register as internal netfilter logging module");
  78
  79 /* global data structures */
  80
  81 typedef struct {
  82         unsigned int qlen;              /* number of nlmsgs' in the skb */
  83         struct nlmsghdr *lastnlh;       /* netlink header of last msg in skb */
  84         struct sk_buff *skb;            /* the pre-allocated skb */
  85         struct timer_list timer;        /* the timer function */
  86 } ulog_buff_t;
  87
  88 static ulog_buff_t ulog_buffers[ULOG_MAXNLGROUPS];      /* array of buffers */
  89
  90 static struct sock *nflognl;            /* our socket */
  91 static DEFINE_SPINLOCK(ulog_lock);      /* spinlock */
  92
  93 /* send one ulog_buff_t to userspace */
  94 static void ulog_send(unsigned int nlgroupnum)
  95 {
  96         ulog_buff_t *ub = &ulog_buffers[nlgroupnum];
  97
  98         if (timer_pending(&ub->timer)) {
  99                 DEBUGP("ipt_ULOG: ulog_send: timer was pending, deleting\n");
 100                 del_timer(&ub->timer);
 101         }
 102
 103         if (!ub->skb) {
 104                 DEBUGP("ipt_ULOG: ulog_send: nothing to send\n");
 105                 return;
 106         }
 107
 108         /* last nlmsg needs NLMSG_DONE */
 109         if (ub->qlen > 1)
 110                 ub->lastnlh->nlmsg_type = NLMSG_DONE;
 111
 112         NETLINK_CB(ub->skb).dst_group = nlgroupnum + 1;
 113         DEBUGP("ipt_ULOG: throwing %d packets to netlink group %u\n",
 114                 ub->qlen, nlgroupnum + 1);
 115         netlink_broadcast(nflognl, ub->skb, 0, nlgroupnum + 1, GFP_ATOMIC);
 116
 117         ub->qlen = 0;
 118         ub->skb = NULL;
 119         ub->lastnlh = NULL;
 120 }
 121
 122
 123 /* timer function to flush queue in flushtimeout time */
 124 static void ulog_timer(unsigned long data)
 125 {
 126         DEBUGP("ipt_ULOG: timer function called, calling ulog_send\n");
 127
 128         /* lock to protect against somebody modifying our structure
 129          * from ipt_ulog_target at the same time */
 130         spin_lock_bh(&ulog_lock);
 131         ulog_send(data);
 132         spin_unlock_bh(&ulog_lock);
 133 }
 134
 135 static struct sk_buff *ulog_alloc_skb(unsigned int size)
 136 {
 137         struct sk_buff *skb;
 138         unsigned int n;
 139
 140         /* alloc skb which should be big enough for a whole
 141          * multipart message. WARNING: has to be <= 131000
 142          * due to slab allocator restrictions */
 143
 144         n = max(size, nlbufsiz);
 145         skb = alloc_skb(n, GFP_ATOMIC);
 146         if (!skb) {
 147                 PRINTR("ipt_ULOG: can't alloc whole buffer %ub!\n", n);
 148
 149                 if (n > size) {
 150                         /* try to allocate only as much as we need for
 151                          * current packet */
 152
 153                         skb = alloc_skb(size, GFP_ATOMIC);
 154                         if (!skb)
 155                                 PRINTR("ipt_ULOG: can't even allocate %ub\n",
 156                                        size);
 157                 }
 158         }
 159
 160         return skb;
 161 }
 162
 163 static void ipt_ulog_packet(unsigned int hooknum,
 164                             const struct sk_buff *skb,
 165                             const struct net_device *in,
 166                             const struct net_device *out,
 167                             const struct ipt_ulog_info *loginfo,
 168                             const char *prefix)
 169 {
 170         ulog_buff_t *ub;
 171         ulog_packet_msg_t *pm;
 172         size_t size, copy_len;
 173         struct nlmsghdr *nlh;
 174         struct timeval tv;
 175
 176         /* ffs == find first bit set, necessary because userspace
 177          * is already shifting groupnumber, but we need unshifted.
 178          * ffs() returns [1..32], we need [0..31] */
 179         unsigned int groupnum = ffs(loginfo->nl_group) - 1;
 180
 181         /* calculate the size of the skb needed */
 182         if ((loginfo->copy_range == 0) ||
 183             (loginfo->copy_range > skb->len)) {
 184                 copy_len = skb->len;
 185         } else {
 186                 copy_len = loginfo->copy_range;
 187         }
 188
 189         size = NLMSG_SPACE(sizeof(*pm) + copy_len);
 190
 191         ub = &ulog_buffers[groupnum];
 192
 193         spin_lock_bh(&ulog_lock);
 194
 195         if (!ub->skb) {
 196                 if (!(ub->skb = ulog_alloc_skb(size)))
 197                         goto alloc_failure;
 198         } else if (ub->qlen >= loginfo->qthreshold ||
 199                    size > skb_tailroom(ub->skb)) {
 200                 /* either the queue len is too high or we don't have
 201                  * enough room in nlskb left. send it to userspace. */
 202
 203                 ulog_send(groupnum);
 204
 205                 if (!(ub->skb = ulog_alloc_skb(size)))
 206                         goto alloc_failure;
 207         }
 208
 209         DEBUGP("ipt_ULOG: qlen %d, qthreshold %d\n", ub->qlen,
 210                 loginfo->qthreshold);
 211
 212         /* NLMSG_PUT contains a hidden goto nlmsg_failure !!! */
 213         nlh = NLMSG_PUT(ub->skb, 0, ub->qlen, ULOG_NL_EVENT,
 214                         sizeof(*pm)+copy_len);
 215         ub->qlen++;
 216
 217         pm = NLMSG_DATA(nlh);
 218
 219         /* We might not have a timestamp, get one */
 220         if (skb->tstamp.tv64 == 0)
 221                 __net_timestamp((struct sk_buff *)skb);
 222
 223         /* copy hook, prefix, timestamp, payload, etc. */
 224         pm->data_len = copy_len;
 225         tv = ktime_to_timeval(skb->tstamp);
 226         put_unaligned(tv.tv_sec, &pm->timestamp_sec);
 227         put_unaligned(tv.tv_usec, &pm->timestamp_usec);
 228         put_unaligned(skb->mark, &pm->mark);
 229         pm->hook = hooknum;
 230         if (prefix != NULL)
 231                 strncpy(pm->prefix, prefix, sizeof(pm->prefix));
 232         else if (loginfo->prefix[0] != '\0')
 233                 strncpy(pm->prefix, loginfo->prefix, sizeof(pm->prefix));
 234         else
 235                 *(pm->prefix) = '\0';
 236
 237         if (in && in->hard_header_len > 0
 238             && skb->mac_header != skb->network_header
 239             && in->hard_header_len <= ULOG_MAC_LEN) {
 240                 memcpy(pm->mac, skb_mac_header(skb), in->hard_header_len);
 241                 pm->mac_len = in->hard_header_len;
 242         } else
 243                 pm->mac_len = 0;
 244
 245         if (in)
 246                 strncpy(pm->indev_name, in->name, sizeof(pm->indev_name));
 247         else
 248                 pm->indev_name[0] = '\0';
 249
 250         if (out)
 251                 strncpy(pm->outdev_name, out->name, sizeof(pm->outdev_name));
 252         else
 253                 pm->outdev_name[0] = '\0';
 254
 255         /* copy_len <= skb->len, so can't fail. */
 256         if (skb_copy_bits(skb, 0, pm->payload, copy_len) < 0)
 257                 BUG();
 258
 259         /* check if we are building multi-part messages */
 260         if (ub->qlen > 1) {
 261                 ub->lastnlh->nlmsg_flags |= NLM_F_MULTI;
 262         }
 263
 264         ub->lastnlh = nlh;
 265
 266         /* if timer isn't already running, start it */
 267         if (!timer_pending(&ub->timer)) {
 268                 ub->timer.expires = jiffies + flushtimeout * HZ / 100;
 269                 add_timer(&ub->timer);
 270         }
 271
 272         /* if threshold is reached, send message to userspace */
 273         if (ub->qlen >= loginfo->qthreshold) {
 274                 if (loginfo->qthreshold > 1)
 275                         nlh->nlmsg_type = NLMSG_DONE;
 276                 ulog_send(groupnum);
 277         }
 278
 279         spin_unlock_bh(&ulog_lock);
 280
 281         return;
 282
 283 nlmsg_failure:
 284         PRINTR("ipt_ULOG: error during NLMSG_PUT\n");
 285
 286 alloc_failure:
 287         PRINTR("ipt_ULOG: Error building netlink message\n");
 288
 289         spin_unlock_bh(&ulog_lock);
 290 }
 291
 292 static unsigned int ipt_ulog_target(struct sk_buff *skb,
 293                                     const struct net_device *in,
 294                                     const struct net_device *out,
 295                                     unsigned int hooknum,
 296                                     const struct xt_target *target,
 297                                     const void *targinfo)
 298 {
 299         struct ipt_ulog_info *loginfo = (struct ipt_ulog_info *) targinfo;
 300
 301         ipt_ulog_packet(hooknum, skb, in, out, loginfo, NULL);
 302
 303         return XT_CONTINUE;
 304 }
 305
 306 static void ipt_logfn(unsigned int pf,
 307                       unsigned int hooknum,
 308                       const struct sk_buff *skb,
 309                       const struct net_device *in,
 310                       const struct net_device *out,
 311                       const struct nf_loginfo *li,
 312                       const char *prefix)
 313 {
 314         struct ipt_ulog_info loginfo;
 315
 316         if (!li || li->type != NF_LOG_TYPE_ULOG) {
 317                 loginfo.nl_group = ULOG_DEFAULT_NLGROUP;
 318                 loginfo.copy_range = 0;
 319                 loginfo.qthreshold = ULOG_DEFAULT_QTHRESHOLD;
 320                 loginfo.prefix[0] = '\0';
 321         } else {
 322                 loginfo.nl_group = li->u.ulog.group;
 323                 loginfo.copy_range = li->u.ulog.copy_len;
 324                 loginfo.qthreshold = li->u.ulog.qthreshold;
 325                 strlcpy(loginfo.prefix, prefix, sizeof(loginfo.prefix));
 326         }
 327
 328         ipt_ulog_packet(hooknum, skb, in, out, &loginfo, prefix);
 329 }
 330
 331 static int ipt_ulog_checkentry(const char *tablename,
 332                                const void *e,
 333                                const struct xt_target *target,
 334                                void *targinfo,
 335                                unsigned int hookmask)
 336 {
 337         struct ipt_ulog_info *loginfo = (struct ipt_ulog_info *) targinfo;
 338
 339         if (loginfo->prefix[sizeof(loginfo->prefix) - 1] != '\0') {
 340                 DEBUGP("ipt_ULOG: prefix term %i\n",
 341                        loginfo->prefix[sizeof(loginfo->prefix) - 1]);
 342                 return 0;
 343         }
 344         if (loginfo->qthreshold > ULOG_MAX_QLEN) {
 345                 DEBUGP("ipt_ULOG: queue threshold %i > MAX_QLEN\n",
 346                         loginfo->qthreshold);
 347                 return 0;
 348         }
 349         return 1;
 350 }
 351
 352 #ifdef CONFIG_COMPAT
 353 struct compat_ipt_ulog_info {
 354         compat_uint_t   nl_group;
 355         compat_size_t   copy_range;
 356         compat_size_t   qthreshold;
 357         char            prefix[ULOG_PREFIX_LEN];
 358 };
 359
 360 static void compat_from_user(void *dst, void *src)
 361 {
 362         struct compat_ipt_ulog_info *cl = src;
 363         struct ipt_ulog_info l = {
 364                 .nl_group       = cl->nl_group,
 365                 .copy_range     = cl->copy_range,
 366                 .qthreshold     = cl->qthreshold,
 367         };
 368
 369         memcpy(l.prefix, cl->prefix, sizeof(l.prefix));
 370         memcpy(dst, &l, sizeof(l));
 371 }
 372
 373 static int compat_to_user(void __user *dst, void *src)
 374 {
 375         struct ipt_ulog_info *l = src;
 376         struct compat_ipt_ulog_info cl = {
 377                 .nl_group       = l->nl_group,
 378                 .copy_range     = l->copy_range,
 379                 .qthreshold     = l->qthreshold,
 380         };
 381
 382         memcpy(cl.prefix, l->prefix, sizeof(cl.prefix));
 383         return copy_to_user(dst, &cl, sizeof(cl)) ? -EFAULT : 0;
 384 }
 385 #endif /* CONFIG_COMPAT */
 386
 387 static struct xt_target ipt_ulog_reg = {
 388         .name           = "ULOG",
 389         .family         = AF_INET,
 390         .target         = ipt_ulog_target,
 391         .targetsize     = sizeof(struct ipt_ulog_info),
 392         .checkentry     = ipt_ulog_checkentry,
 393 #ifdef CONFIG_COMPAT
 394         .compatsize     = sizeof(struct compat_ipt_ulog_info),
 395         .compat_from_user = compat_from_user,
 396         .compat_to_user = compat_to_user,
 397 #endif
 398         .me             = THIS_MODULE,
 399 };
 400
 401 static struct nf_logger ipt_ulog_logger = {
 402         .name           = "ipt_ULOG",
 403         .logfn          = ipt_logfn,
 404         .me             = THIS_MODULE,
 405 };
 406
 407 static int __init ipt_ulog_init(void)
 408 {
 409         int ret, i;
 410
 411         DEBUGP("ipt_ULOG: init module\n");
 412
 413         if (nlbufsiz > 128*1024) {
 414                 printk("Netlink buffer has to be <= 128kB\n");
 415                 return -EINVAL;
 416         }
 417
 418         /* initialize ulog_buffers */
 419         for (i = 0; i < ULOG_MAXNLGROUPS; i++)
 420                 setup_timer(&ulog_buffers[i].timer, ulog_timer, i);
 421
 422         nflognl = netlink_kernel_create(NETLINK_NFLOG, ULOG_MAXNLGROUPS, NULL,
 423                                         NULL, THIS_MODULE);
 424         if (!nflognl)
 425                 return -ENOMEM;
 426
 427         ret = xt_register_target(&ipt_ulog_reg);
 428         if (ret < 0) {
 429                 sock_release(nflognl->sk_socket);
 430                 return ret;
 431         }
 432         if (nflog)
 433                 nf_log_register(PF_INET, &ipt_ulog_logger);
 434
 435         return 0;
 436 }
 437
 438 static void __exit ipt_ulog_fini(void)
 439 {
 440         ulog_buff_t *ub;
 441         int i;
 442
 443         DEBUGP("ipt_ULOG: cleanup_module\n");
 444
 445         if (nflog)
 446                 nf_log_unregister(&ipt_ulog_logger);
 447         xt_unregister_target(&ipt_ulog_reg);
 448         sock_release(nflognl->sk_socket);
 449
 450         /* remove pending timers and free allocated skb's */
 451         for (i = 0; i < ULOG_MAXNLGROUPS; i++) {
 452                 ub = &ulog_buffers[i];
 453                 if (timer_pending(&ub->timer)) {
 454                         DEBUGP("timer was pending, deleting\n");
 455                         del_timer(&ub->timer);
 456                 }
 457
 458                 if (ub->skb) {
 459                         kfree_skb(ub->skb);
 460                         ub->skb = NULL;
 461                 }
 462         }
 463 }
 464
 465 module_init(ipt_ulog_init);
 466 module_exit(ipt_ulog_fini);