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