1/* 2 * netfilter module for userspace packet logging daemons 3 * 4 * (C) 2000-2002 by Harald Welte <laforge@gnumonks.org> 5 * 6 * 2000/09/22 ulog-cprange feature added 7 * 2001/01/04 in-kernel queue as proposed by Sebastian Zander 8 * <zander@fokus.gmd.de> 9 * 2001/01/30 per-rule nlgroup conflicts with global queue. 10 * nlgroup now global (sysctl) 11 * 2001/04/19 ulog-queue reworked, now fixed buffer size specified at 12 * module loadtime -HW 13 * 2002/07/07 remove broken nflog_rcv() function -HW 14 * 2002/08/29 fix shifted/unshifted nlgroup bug -HW 15 * 2002/10/30 fix uninitialized mac_len field - <Anders K. Pedersen> 16 * 17 * Released under the terms of the GPL 18 * 19 * This module accepts two parameters: 20 * 21 * nlbufsiz: 22 * The parameter specifies how big the buffer for each netlink multicast 23 * group is. e.g. If you say nlbufsiz=8192, up to eight kb of packets will 24 * get accumulated in the kernel until they are sent to userspace. It is 25 * NOT possible to allocate more than 128kB, and it is strongly discouraged, 26 * because atomically allocating 128kB inside the network rx softirq is not 27 * reliable. Please also keep in mind that this buffer size is allocated for 28 * each nlgroup you are using, so the total kernel memory usage increases 29 * by that factor. 30 * 31 * flushtimeout: 32 * Specify, after how many clock ticks (intel: 100 per second) the queue 33 * should be flushed even if it is not full yet. 34 * 35 * ipt_ULOG.c,v 1.22 2002/10/30 09:07:31 laforge Exp 36 */ 37 38#include <linux/module.h> 39#include <linux/version.h> 40#include <linux/config.h> 41#include <linux/spinlock.h> 42#include <linux/socket.h> 43#include <linux/skbuff.h> 44#include <linux/kernel.h> 45#include <linux/timer.h> 46#include <linux/netlink.h> 47#include <linux/netdevice.h> 48#include <linux/mm.h> 49#include <linux/socket.h> 50#include <linux/netfilter_ipv4/ip_tables.h> 51#include <linux/netfilter_ipv4/ipt_ULOG.h> 52#include <linux/netfilter_ipv4/lockhelp.h> 53#include <net/sock.h> 54#include <linux/bitops.h> 55 56MODULE_LICENSE("GPL"); 57MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>"); 58MODULE_DESCRIPTION("IP tables userspace logging module"); 59 60#define ULOG_NL_EVENT 111 /* Harald's favorite number */ 61#define ULOG_MAXNLGROUPS 32 /* numer of nlgroups */ 62 63#define DEBUGP(format, args...) 64 65#define PRINTR(format, args...) do { if (net_ratelimit()) printk(format, ## args); } while (0) 66 67static unsigned int nlbufsiz = 4096; 68MODULE_PARM(nlbufsiz, "i"); 69MODULE_PARM_DESC(nlbufsiz, "netlink buffer size"); 70 71static unsigned int flushtimeout = 10 * HZ; 72MODULE_PARM(flushtimeout, "i"); 73MODULE_PARM_DESC(flushtimeout, "buffer flush timeout"); 74 75/* global data structures */ 76 77typedef struct { 78 unsigned int qlen; /* number of nlmsgs' in the skb */ 79 struct nlmsghdr *lastnlh; /* netlink header of last msg in skb */ 80 struct sk_buff *skb; /* the pre-allocated skb */ 81 struct timer_list timer; /* the timer function */ 82} ulog_buff_t; 83 84static ulog_buff_t ulog_buffers[ULOG_MAXNLGROUPS]; /* array of buffers */ 85 86static struct sock *nflognl; /* our socket */ 87static size_t qlen; /* current length of multipart-nlmsg */ 88DECLARE_LOCK(ulog_lock); /* spinlock */ 89 90/* send one ulog_buff_t to userspace */ 91static void ulog_send(unsigned int nlgroupnum) 92{ 93 ulog_buff_t *ub = &ulog_buffers[nlgroupnum]; 94 95 if (timer_pending(&ub->timer)) { 96 DEBUGP("ipt_ULOG: ulog_send: timer was pending, deleting\n"); 97 del_timer(&ub->timer); 98 } 99 100 /* last nlmsg needs NLMSG_DONE */ 101 if (ub->qlen > 1) 102 ub->lastnlh->nlmsg_type = NLMSG_DONE; 103 104 NETLINK_CB(ub->skb).dst_groups = (1 << nlgroupnum); 105 DEBUGP("ipt_ULOG: throwing %d packets to netlink mask %u\n", 106 ub->qlen, nlgroup); 107 netlink_broadcast(nflognl, ub->skb, 0, (1 << nlgroupnum), GFP_ATOMIC); 108 109 ub->qlen = 0; 110 ub->skb = NULL; 111 ub->lastnlh = NULL; 112 113} 114 115 116/* timer function to flush queue in ULOG_FLUSH_INTERVAL time */ 117static void ulog_timer(unsigned long data) 118{ 119 DEBUGP("ipt_ULOG: timer function called, calling ulog_send\n"); 120 121 /* lock to protect against somebody modifying our structure 122 * from ipt_ulog_target at the same time */ 123 LOCK_BH(&ulog_lock); 124 ulog_send(data); 125 UNLOCK_BH(&ulog_lock); 126} 127 128struct sk_buff *ulog_alloc_skb(unsigned int size) 129{ 130 struct sk_buff *skb; 131 132 /* alloc skb which should be big enough for a whole 133 * multipart message. WARNING: has to be <= 131000 134 * due to slab allocator restrictions */ 135 136 skb = alloc_skb(nlbufsiz, GFP_ATOMIC); 137 if (!skb) { 138 PRINTR("ipt_ULOG: can't alloc whole buffer %ub!\n", 139 nlbufsiz); 140 141 /* try to allocate only as much as we need for 142 * current packet */ 143 144 skb = alloc_skb(size, GFP_ATOMIC); 145 if (!skb) 146 PRINTR("ipt_ULOG: can't even allocate %ub\n", size); 147 } 148 149 return skb; 150} 151 152static unsigned int ipt_ulog_target(struct sk_buff **pskb, 153 unsigned int hooknum, 154 const struct net_device *in, 155 const struct net_device *out, 156 const void *targinfo, void *userinfo) 157{ 158 ulog_buff_t *ub; 159 ulog_packet_msg_t *pm; 160 size_t size, copy_len; 161 struct nlmsghdr *nlh; 162 struct ipt_ulog_info *loginfo = (struct ipt_ulog_info *) targinfo; 163 164 /* ffs == find first bit set, necessary because userspace 165 * is already shifting groupnumber, but we need unshifted. 166 * ffs() returns [1..32], we need [0..31] */ 167 unsigned int groupnum = ffs(loginfo->nl_group) - 1; 168 169 /* calculate the size of the skb needed */ 170 if ((loginfo->copy_range == 0) || 171 (loginfo->copy_range > (*pskb)->len)) { 172 copy_len = (*pskb)->len; 173 } else { 174 copy_len = loginfo->copy_range; 175 } 176 177 size = NLMSG_SPACE(sizeof(*pm) + copy_len); 178 179 ub = &ulog_buffers[groupnum]; 180 181 LOCK_BH(&ulog_lock); 182 183 if (!ub->skb) { 184 if (!(ub->skb = ulog_alloc_skb(size))) 185 goto alloc_failure; 186 } else if (ub->qlen >= loginfo->qthreshold || 187 size > skb_tailroom(ub->skb)) { 188 /* either the queue len is too high or we don't have 189 * enough room in nlskb left. send it to userspace. */ 190 191 ulog_send(groupnum); 192 193 if (!(ub->skb = ulog_alloc_skb(size))) 194 goto alloc_failure; 195 } 196 197 DEBUGP("ipt_ULOG: qlen %d, qthreshold %d\n", ub->qlen, 198 loginfo->qthreshold); 199 200 /* NLMSG_PUT contains a hidden goto nlmsg_failure !!! */ 201 nlh = NLMSG_PUT(ub->skb, 0, ub->qlen, ULOG_NL_EVENT, 202 size - sizeof(*nlh)); 203 ub->qlen++; 204 205 pm = NLMSG_DATA(nlh); 206 207 /* copy hook, prefix, timestamp, payload, etc. */ 208 pm->data_len = copy_len; 209 pm->timestamp_sec = (*pskb)->stamp.tv_sec; 210 pm->timestamp_usec = (*pskb)->stamp.tv_usec; 211 pm->mark = (*pskb)->nfmark; 212 pm->hook = hooknum; 213 if (loginfo->prefix[0] != '\0') 214 strncpy(pm->prefix, loginfo->prefix, sizeof(pm->prefix)); 215 else 216 *(pm->prefix) = '\0'; 217 218 if (in && in->hard_header_len > 0 219 && (*pskb)->mac.raw != (void *) (*pskb)->nh.iph 220 && in->hard_header_len <= ULOG_MAC_LEN) { 221 memcpy(pm->mac, (*pskb)->mac.raw, in->hard_header_len); 222 pm->mac_len = in->hard_header_len; 223 } else 224 pm->mac_len = 0; 225 226 if (in) 227 strncpy(pm->indev_name, in->name, sizeof(pm->indev_name)); 228 else 229 pm->indev_name[0] = '\0'; 230 231 if (out) 232 strncpy(pm->outdev_name, out->name, sizeof(pm->outdev_name)); 233 else 234 pm->outdev_name[0] = '\0'; 235 236 if (copy_len) 237 memcpy(pm->payload, (*pskb)->data, copy_len); 238 239 /* check if we are building multi-part messages */ 240 if (ub->qlen > 1) { 241 ub->lastnlh->nlmsg_flags |= NLM_F_MULTI; 242 } 243 244 /* if threshold is reached, send message to userspace */ 245 if (qlen >= loginfo->qthreshold) { 246 if (loginfo->qthreshold > 1) 247 nlh->nlmsg_type = NLMSG_DONE; 248 } 249 250 ub->lastnlh = nlh; 251 252 /* if timer isn't already running, start it */ 253 if (!timer_pending(&ub->timer)) { 254 ub->timer.expires = jiffies + flushtimeout; 255 add_timer(&ub->timer); 256 } 257 258 UNLOCK_BH(&ulog_lock); 259 260 return IPT_CONTINUE; 261 262 263nlmsg_failure: 264 PRINTR("ipt_ULOG: error during NLMSG_PUT\n"); 265 266alloc_failure: 267 PRINTR("ipt_ULOG: Error building netlink message\n"); 268 269 UNLOCK_BH(&ulog_lock); 270 271 return IPT_CONTINUE; 272} 273 274static int ipt_ulog_checkentry(const char *tablename, 275 const struct ipt_entry *e, 276 void *targinfo, 277 unsigned int targinfosize, 278 unsigned int hookmask) 279{ 280 struct ipt_ulog_info *loginfo = (struct ipt_ulog_info *) targinfo; 281 282 if (targinfosize != IPT_ALIGN(sizeof(struct ipt_ulog_info))) { 283 DEBUGP("ipt_ULOG: targinfosize %u != 0\n", targinfosize); 284 return 0; 285 } 286 287 if (loginfo->prefix[sizeof(loginfo->prefix) - 1] != '\0') { 288 DEBUGP("ipt_ULOG: prefix term %i\n", 289 loginfo->prefix[sizeof(loginfo->prefix) - 1]); 290 return 0; 291 } 292 293 if (loginfo->qthreshold > ULOG_MAX_QLEN) { 294 DEBUGP("ipt_ULOG: queue threshold %i > MAX_QLEN\n", 295 loginfo->qthreshold); 296 return 0; 297 } 298 299 return 1; 300} 301 302static struct ipt_target ipt_ulog_reg = 303 { {NULL, NULL}, "ULOG", ipt_ulog_target, ipt_ulog_checkentry, NULL, 304THIS_MODULE 305}; 306 307static int __init init(void) 308{ 309 int i; 310 311 DEBUGP("ipt_ULOG: init module\n"); 312 313 if (nlbufsiz >= 128*1024) { 314 printk("Netlink buffer has to be <= 128kB\n"); 315 return -EINVAL; 316 } 317 318 /* initialize ulog_buffers */ 319 for (i = 0; i < ULOG_MAXNLGROUPS; i++) { 320 memset(&ulog_buffers[i], 0, sizeof(ulog_buff_t)); 321 init_timer(&ulog_buffers[i].timer); 322 ulog_buffers[i].timer.function = ulog_timer; 323 ulog_buffers[i].timer.data = i; 324 } 325 326 nflognl = netlink_kernel_create(NETLINK_NFLOG, NULL); 327 if (!nflognl) 328 return -ENOMEM; 329 330 if (ipt_register_target(&ipt_ulog_reg) != 0) { 331 sock_release(nflognl->socket); 332 return -EINVAL; 333 } 334 335 return 0; 336} 337 338static void __exit fini(void) 339{ 340 ulog_buff_t *ub; 341 int i; 342 343 DEBUGP("ipt_ULOG: cleanup_module\n"); 344 345 ipt_unregister_target(&ipt_ulog_reg); 346 sock_release(nflognl->socket); 347 348 /* remove pending timers and free allocated skb's */ 349 for (i = 0; i < ULOG_MAXNLGROUPS; i++) { 350 ub = &ulog_buffers[i]; 351 if (timer_pending(&ub->timer)) { 352 DEBUGP("timer was pending, deleting\n"); 353 del_timer(&ub->timer); 354 } 355 356 if (ub->skb) { 357 kfree_skb(ub->skb); 358 ub->skb = NULL; 359 } 360 } 361 362} 363 364module_init(init); 365module_exit(fini); 366