net/ipv4/netfilter/ipt_recent.c

   1 /* Kernel module to check if the source address has been seen recently. */
   2 /* Copyright 2002-2003, Stephen Frost, 2.5.x port by laforge@netfilter.org */
   3 /* Author: Stephen Frost <sfrost@snowman.net> */
   4 /* Project Page: http://snowman.net/projects/ipt_recent/ */
   5 /* This software is distributed under the terms of the GPL, Version 2 */
   6 /* This copyright does not cover user programs that use kernel services
   7  * by normal system calls. */
   8
   9 #include <linux/module.h>
  10 #include <linux/skbuff.h>
  11 #include <linux/proc_fs.h>
  12 #include <linux/spinlock.h>
  13 #include <linux/interrupt.h>
  14 #include <asm/uaccess.h>
  15 #include <linux/ctype.h>
  16 #include <linux/ip.h>
  17 #include <linux/vmalloc.h>
  18 #include <linux/moduleparam.h>
  19
  20 #include <linux/netfilter_ipv4/ip_tables.h>
  21 #include <linux/netfilter_ipv4/ipt_recent.h>
  22
  23 #undef DEBUG
  24 #define HASH_LOG 9
  25
  26 /* Defaults, these can be overridden on the module command-line. */
  27 static int ip_list_tot = 100;
  28 static int ip_pkt_list_tot = 20;
  29 static int ip_list_hash_size = 0;
  30 static int ip_list_perms = 0644;
  31 #ifdef DEBUG
  32 static int debug = 1;
  33 #endif
  34
  35 static char version[] =
  36 KERN_INFO RECENT_NAME " " RECENT_VER ": Stephen Frost <sfrost@snowman.net>.  http://snowman.net/projects/ipt_recent/\n";
  37
  38 MODULE_AUTHOR("Stephen Frost <sfrost@snowman.net>");
  39 MODULE_DESCRIPTION("IP tables recently seen matching module " RECENT_VER);
  40 MODULE_LICENSE("GPL");
  41 module_param(ip_list_tot, int, 0400);
  42 module_param(ip_pkt_list_tot, int, 0400);
  43 module_param(ip_list_hash_size, int, 0400);
  44 module_param(ip_list_perms, int, 0400);
  45 #ifdef DEBUG
  46 module_param(debug, int, 0600);
  47 MODULE_PARM_DESC(debug,"debugging level, defaults to 1");
  48 #endif
  49 MODULE_PARM_DESC(ip_list_tot,"number of IPs to remember per list");
  50 MODULE_PARM_DESC(ip_pkt_list_tot,"number of packets per IP to remember");
  51 MODULE_PARM_DESC(ip_list_hash_size,"size of hash table used to look up IPs");
  52 MODULE_PARM_DESC(ip_list_perms,"permissions on /proc/net/ipt_recent/* files");
  53
  54 /* Structure of our list of recently seen addresses. */
  55 struct recent_ip_list {
  56         u_int32_t addr;
  57         u_int8_t  ttl;
  58         unsigned long last_seen;
  59         unsigned long *last_pkts;
  60         u_int32_t oldest_pkt;
  61         u_int32_t hash_entry;
  62         u_int32_t time_pos;
  63 };
  64
  65 struct time_info_list {
  66         u_int32_t position;
  67         u_int32_t time;
  68 };
  69
  70 /* Structure of our linked list of tables of recent lists. */
  71 struct recent_ip_tables {
  72         char name[IPT_RECENT_NAME_LEN];
  73         int count;
  74         int time_pos;
  75         struct recent_ip_list *table;
  76         struct recent_ip_tables *next;
  77         spinlock_t list_lock;
  78         int *hash_table;
  79         struct time_info_list *time_info;
  80 #ifdef CONFIG_PROC_FS
  81         struct proc_dir_entry *status_proc;
  82 #endif /* CONFIG_PROC_FS */
  83 };
  84
  85 /* Our current list of addresses we have recently seen.
  86  * Only added to on a --set, and only updated on --set || --update
  87  */
  88 static struct recent_ip_tables *r_tables = NULL;
  89
  90 /* We protect r_list with this spinlock so two processors are not modifying
  91  * the list at the same time.
  92  */
  93 static DEFINE_SPINLOCK(recent_lock);
  94
  95 #ifdef CONFIG_PROC_FS
  96 /* Our /proc/net/ipt_recent entry */
  97 static struct proc_dir_entry *proc_net_ipt_recent = NULL;
  98 #endif
  99
 100 /* Function declaration for later. */
 101 static int
 102 match(const struct sk_buff *skb,
 103       const struct net_device *in,
 104       const struct net_device *out,
 105       const void *matchinfo,
 106       int offset,
 107       int *hotdrop);
 108
 109 /* Function to hash a given address into the hash table of table_size size */
 110 static int hash_func(unsigned int addr, int table_size)
 111 {
 112         int result = 0;
 113         unsigned int value = addr;
 114         do { result ^= value; } while((value >>= HASH_LOG));
 115
 116 #ifdef DEBUG
 117         if(debug) printk(KERN_INFO RECENT_NAME ": %d = hash_func(%u,%d)\n",
 118                          result & (table_size - 1),
 119                          addr,
 120                          table_size);
 121 #endif
 122
 123         return(result & (table_size - 1));
 124 }
 125
 126 #ifdef CONFIG_PROC_FS
 127 /* This is the function which produces the output for our /proc output
 128  * interface which lists each IP address, the last seen time and the
 129  * other recent times the address was seen.
 130  */
 131
 132 static int ip_recent_get_info(char *buffer, char **start, off_t offset, int length, int *eof, void *data)
 133 {
 134         int len = 0, count, last_len = 0, pkt_count;
 135         off_t pos = 0;
 136         off_t begin = 0;
 137         struct recent_ip_tables *curr_table;
 138
 139         curr_table = (struct recent_ip_tables*) data;
 140
 141         spin_lock_bh(&curr_table->list_lock);
 142         for(count = 0; count < ip_list_tot; count++) {
 143                 if(!curr_table->table[count].addr) continue;
 144                 last_len = len;
 145                 len += sprintf(buffer+len,"src=%u.%u.%u.%u ",NIPQUAD(curr_table->table[count].addr));
 146                 len += sprintf(buffer+len,"ttl: %u ",curr_table->table[count].ttl);
 147                 len += sprintf(buffer+len,"last_seen: %lu ",curr_table->table[count].last_seen);
 148                 len += sprintf(buffer+len,"oldest_pkt: %u ",curr_table->table[count].oldest_pkt);
 149                 len += sprintf(buffer+len,"last_pkts: %lu",curr_table->table[count].last_pkts[0]);
 150                 for(pkt_count = 1; pkt_count < ip_pkt_list_tot; pkt_count++) {
 151                         if(!curr_table->table[count].last_pkts[pkt_count]) break;
 152                         len += sprintf(buffer+len,", %lu",curr_table->table[count].last_pkts[pkt_count]);
 153                 }
 154                 len += sprintf(buffer+len,"\n");
 155                 pos = begin + len;
 156                 if(pos < offset) { len = 0; begin = pos; }
 157                 if(pos > offset + length) { len = last_len; break; }
 158         }
 159
 160         *start = buffer + (offset - begin);
 161         len -= (offset - begin);
 162         if(len > length) len = length;
 163
 164         spin_unlock_bh(&curr_table->list_lock);
 165         return len;
 166 }
 167
 168 /* ip_recent_ctrl provides an interface for users to modify the table
 169  * directly.  This allows adding entries, removing entries, and
 170  * flushing the entire table.
 171  * This is done by opening up the appropriate table for writing and
 172  * sending one of:
 173  * xx.xx.xx.xx   -- Add entry to table with current time
 174  * +xx.xx.xx.xx  -- Add entry to table with current time
 175  * -xx.xx.xx.xx  -- Remove entry from table
 176  * clear         -- Flush table, remove all entries
 177  */
 178
 179 static int ip_recent_ctrl(struct file *file, const char __user *input, unsigned long size, void *data)
 180 {
 181         static const u_int32_t max[4] = { 0xffffffff, 0xffffff, 0xffff, 0xff };
 182         u_int32_t val;
 183         int base, used = 0;
 184         char c, *cp;
 185         union iaddr {
 186                 uint8_t bytes[4];
 187                 uint32_t word;
 188         } res;
 189         uint8_t *pp = res.bytes;
 190         int digit;
 191
 192         char buffer[20];
 193         int len, check_set = 0, count;
 194         u_int32_t addr = 0;
 195         struct sk_buff *skb;
 196         struct ipt_recent_info *info;
 197         struct recent_ip_tables *curr_table;
 198
 199         curr_table = (struct recent_ip_tables*) data;
 200
 201         if(size > 20) len = 20; else len = size;
 202
 203         if(copy_from_user(buffer,input,len)) return -EFAULT;
 204
 205         if(len < 20) buffer[len] = '\0';
 206
 207 #ifdef DEBUG
 208         if(debug) printk(KERN_INFO RECENT_NAME ": ip_recent_ctrl len: %d, input: `%.20s'\n",len,buffer);
 209 #endif
 210
 211         cp = buffer;
 212         while(isspace(*cp)) { cp++; used++; if(used >= len-5) return used; }
 213
 214         /* Check if we are asked to flush the entire table */
 215         if(!memcmp(cp,"clear",5)) {
 216                 used += 5;
 217                 spin_lock_bh(&curr_table->list_lock);
 218                 curr_table->time_pos = 0;
 219                 for(count = 0; count < ip_list_hash_size; count++) {
 220                         curr_table->hash_table[count] = -1;
 221                 }
 222                 for(count = 0; count < ip_list_tot; count++) {
 223                         curr_table->table[count].last_seen = 0;
 224                         curr_table->table[count].addr = 0;
 225                         curr_table->table[count].ttl = 0;
 226                         memset(curr_table->table[count].last_pkts,0,ip_pkt_list_tot*sizeof(u_int32_t));
 227                         curr_table->table[count].oldest_pkt = 0;
 228                         curr_table->table[count].time_pos = 0;
 229                         curr_table->time_info[count].position = count;
 230                         curr_table->time_info[count].time = 0;
 231                 }
 232                 spin_unlock_bh(&curr_table->list_lock);
 233                 return used;
 234         }
 235
 236         check_set = IPT_RECENT_SET;
 237         switch(*cp) {
 238                 case '+': check_set = IPT_RECENT_SET; cp++; used++; break;
 239                 case '-': check_set = IPT_RECENT_REMOVE; cp++; used++; break;
 240                 default: if(!isdigit(*cp)) return (used+1); break;
 241         }
 242
 243 #ifdef DEBUG
 244         if(debug) printk(KERN_INFO RECENT_NAME ": ip_recent_ctrl cp: `%c', check_set: %d\n",*cp,check_set);
 245 #endif
 246         /* Get addr (effectively inet_aton()) */
 247         /* Shamelessly stolen from libc, a function in the kernel for doing
 248          * this would, of course, be greatly preferred, but our options appear
 249          * to be rather limited, so we will just do it ourselves here.
 250          */
 251         res.word = 0;
 252
 253         c = *cp;
 254         for(;;) {
 255                 if(!isdigit(c)) return used;
 256                 val = 0; base = 10; digit = 0;
 257                 if(c == '0') {
 258                         c = *++cp;
 259                         if(c == 'x' || c == 'X') base = 16, c = *++cp;
 260                         else { base = 8; digit = 1; }
 261                 }
 262                 for(;;) {
 263                         if(isascii(c) && isdigit(c)) {
 264                                 if(base == 8 && (c == '8' || c == '0')) return used;
 265                                 val = (val * base) + (c - '0');
 266                                 c = *++cp;
 267                                 digit = 1;
 268                         } else if(base == 16 && isascii(c) && isxdigit(c)) {
 269                                 val = (val << 4) | (c + 10 - (islower(c) ? 'a' : 'A'));
 270                                 c = *++cp;
 271                                 digit = 1;
 272                         } else break;
 273                 }
 274                 if(c == '.') {
 275                         if(pp > res.bytes + 2 || val > 0xff) return used;
 276                         *pp++ = val;
 277                         c = *++cp;
 278                 } else break;
 279         }
 280         used = cp - buffer;
 281         if(c != '\0' && (!isascii(c) || !isspace(c))) return used;
 282         if(c == '\n') used++;
 283         if(!digit) return used;
 284
 285         if(val > max[pp - res.bytes]) return used;
 286         addr = res.word | htonl(val);
 287
 288         if(!addr && check_set == IPT_RECENT_SET) return used;
 289
 290 #ifdef DEBUG
 291         if(debug) printk(KERN_INFO RECENT_NAME ": ip_recent_ctrl c: %c, addr: %u used: %d\n",c,addr,used);
 292 #endif
 293
 294         /* Set up and just call match */
 295         info = kmalloc(sizeof(struct ipt_recent_info),GFP_KERNEL);
 296         if(!info) { return -ENOMEM; }
 297         info->seconds = 0;
 298         info->hit_count = 0;
 299         info->check_set = check_set;
 300         info->invert = 0;
 301         info->side = IPT_RECENT_SOURCE;
 302         strncpy(info->name,curr_table->name,IPT_RECENT_NAME_LEN);
 303         info->name[IPT_RECENT_NAME_LEN-1] = '\0';
 304
 305         skb = kmalloc(sizeof(struct sk_buff),GFP_KERNEL);
 306         if (!skb) {
 307                 used = -ENOMEM;
 308                 goto out_free_info;
 309         }
 310         skb->nh.iph = kmalloc(sizeof(struct iphdr),GFP_KERNEL);
 311         if (!skb->nh.iph) {
 312                 used = -ENOMEM;
 313                 goto out_free_skb;
 314         }
 315
 316         skb->nh.iph->saddr = addr;
 317         skb->nh.iph->daddr = 0;
 318         /* Clear ttl since we have no way of knowing it */
 319         skb->nh.iph->ttl = 0;
 320         match(skb,NULL,NULL,info,0,NULL);
 321
 322         kfree(skb->nh.iph);
 323 out_free_skb:
 324         kfree(skb);
 325 out_free_info:
 326         kfree(info);
 327
 328 #ifdef DEBUG
 329         if(debug) printk(KERN_INFO RECENT_NAME ": Leaving ip_recent_ctrl addr: %u used: %d\n",addr,used);
 330 #endif
 331         return used;
 332 }
 333
 334 #endif /* CONFIG_PROC_FS */
 335
 336 /* 'match' is our primary function, called by the kernel whenever a rule is
 337  * hit with our module as an option to it.
 338  * What this function does depends on what was specifically asked of it by
 339  * the user:
 340  * --set -- Add or update last seen time of the source address of the packet
 341  *   -- matchinfo->check_set == IPT_RECENT_SET
 342  * --rcheck -- Just check if the source address is in the list
 343  *   -- matchinfo->check_set == IPT_RECENT_CHECK
 344  * --update -- If the source address is in the list, update last_seen
 345  *   -- matchinfo->check_set == IPT_RECENT_UPDATE
 346  * --remove -- If the source address is in the list, remove it
 347  *   -- matchinfo->check_set == IPT_RECENT_REMOVE
 348  * --seconds -- Option to --rcheck/--update, only match if last_seen within seconds
 349  *   -- matchinfo->seconds
 350  * --hitcount -- Option to --rcheck/--update, only match if seen hitcount times
 351  *   -- matchinfo->hit_count
 352  * --seconds and --hitcount can be combined
 353  */
 354 static int
 355 match(const struct sk_buff *skb,
 356       const struct net_device *in,
 357       const struct net_device *out,
 358       const void *matchinfo,
 359       int offset,
 360       int *hotdrop)
 361 {
 362         int pkt_count, hits_found, ans;
 363         unsigned long now;
 364         const struct ipt_recent_info *info = matchinfo;
 365         u_int32_t addr = 0, time_temp;
 366         u_int8_t ttl = skb->nh.iph->ttl;
 367         int *hash_table;
 368         int orig_hash_result, hash_result, temp, location = 0, time_loc, end_collision_chain = -1;
 369         struct time_info_list *time_info;
 370         struct recent_ip_tables *curr_table;
 371         struct recent_ip_tables *last_table;
 372         struct recent_ip_list *r_list;
 373
 374 #ifdef DEBUG
 375         if(debug) printk(KERN_INFO RECENT_NAME ": match() called\n");
 376 #endif
 377
 378         /* Default is false ^ info->invert */
 379         ans = info->invert;
 380
 381 #ifdef DEBUG
 382         if(debug) printk(KERN_INFO RECENT_NAME ": match(): name = '%s'\n",info->name);
 383 #endif
 384
 385         /* if out != NULL then routing has been done and TTL changed.
 386          * We change it back here internally for match what came in before routing. */
 387         if(out) ttl++;
 388
 389         /* Find the right table */
 390         spin_lock_bh(&recent_lock);
 391         curr_table = r_tables;
 392         while( (last_table = curr_table) && strncmp(info->name,curr_table->name,IPT_RECENT_NAME_LEN) && (curr_table = curr_table->next) );
 393
 394 #ifdef DEBUG
 395         if(debug) printk(KERN_INFO RECENT_NAME ": match(): table found('%s')\n",info->name);
 396 #endif
 397
 398         spin_unlock_bh(&recent_lock);
 399
 400         /* Table with this name not found, match impossible */
 401         if(!curr_table) { return ans; }
 402
 403         /* Make sure no one is changing the list while we work with it */
 404         spin_lock_bh(&curr_table->list_lock);
 405
 406         r_list = curr_table->table;
 407         if(info->side == IPT_RECENT_DEST) addr = skb->nh.iph->daddr; else addr = skb->nh.iph->saddr;
 408
 409         if(!addr) {
 410 #ifdef DEBUG
 411                 if(debug) printk(KERN_INFO RECENT_NAME ": match() address (%u) invalid, leaving.\n",addr);
 412 #endif
 413                 spin_unlock_bh(&curr_table->list_lock);
 414                 return ans;
 415         }
 416
 417 #ifdef DEBUG
 418         if(debug) printk(KERN_INFO RECENT_NAME ": match(): checking table, addr: %u, ttl: %u, orig_ttl: %u\n",addr,ttl,skb->nh.iph->ttl);
 419 #endif
 420
 421         /* Get jiffies now in case they changed while we were waiting for a lock */
 422         now = jiffies;
 423         hash_table = curr_table->hash_table;
 424         time_info = curr_table->time_info;
 425
 426         orig_hash_result = hash_result = hash_func(addr,ip_list_hash_size);
 427         /* Hash entry at this result used */
 428         /* Check for TTL match if requested.  If TTL is zero then a match would never
 429          * happen, so match regardless of existing TTL in that case.  Zero means the
 430          * entry was added via the /proc interface anyway, so we will just use the
 431          * first TTL we get for that IP address. */
 432         if(info->check_set & IPT_RECENT_TTL) {
 433                 while(hash_table[hash_result] != -1 && !(r_list[hash_table[hash_result]].addr == addr &&
 434                         (!r_list[hash_table[hash_result]].ttl || r_list[hash_table[hash_result]].ttl == ttl))) {
 435                         /* Collision in hash table */
 436                         hash_result = (hash_result + 1) % ip_list_hash_size;
 437                 }
 438         } else {
 439                 while(hash_table[hash_result] != -1 && r_list[hash_table[hash_result]].addr != addr) {
 440                         /* Collision in hash table */
 441                         hash_result = (hash_result + 1) % ip_list_hash_size;
 442                 }
 443         }
 444
 445         if(hash_table[hash_result] == -1 && !(info->check_set & IPT_RECENT_SET)) {
 446                 /* IP not in list and not asked to SET */
 447                 spin_unlock_bh(&curr_table->list_lock);
 448                 return ans;
 449         }
 450
 451         /* Check if we need to handle the collision, do not need to on REMOVE */
 452         if(orig_hash_result != hash_result && !(info->check_set & IPT_RECENT_REMOVE)) {
 453 #ifdef DEBUG
 454                 if(debug) printk(KERN_INFO RECENT_NAME ": match(): Collision in hash table. (or: %d,hr: %d,oa: %u,ha: %u)\n",
 455                                  orig_hash_result,
 456                                  hash_result,
 457                                  r_list[hash_table[orig_hash_result]].addr,
 458                                  addr);
 459 #endif
 460
 461                 /* We had a collision.
 462                  * orig_hash_result is where we started, hash_result is where we ended up.
 463                  * So, swap them because we are likely to see the same guy again sooner */
 464 #ifdef DEBUG
 465                 if(debug) {
 466                   printk(KERN_INFO RECENT_NAME ": match(): Collision; hash_table[orig_hash_result] = %d\n",hash_table[orig_hash_result]);
 467                   printk(KERN_INFO RECENT_NAME ": match(): Collision; r_list[hash_table[orig_hash_result]].hash_entry = %d\n",
 468                                 r_list[hash_table[orig_hash_result]].hash_entry);
 469                 }
 470 #endif
 471
 472                 r_list[hash_table[orig_hash_result]].hash_entry = hash_result;
 473
 474
 475                 temp = hash_table[orig_hash_result];
 476 #ifdef DEBUG
 477                 if(debug) printk(KERN_INFO RECENT_NAME ": match(): Collision; hash_table[hash_result] = %d\n",hash_table[hash_result]);
 478 #endif
 479                 hash_table[orig_hash_result] = hash_table[hash_result];
 480                 hash_table[hash_result] = temp;
 481                 temp = hash_result;
 482                 hash_result = orig_hash_result;
 483                 orig_hash_result = temp;
 484                 time_info[r_list[hash_table[orig_hash_result]].time_pos].position = hash_table[orig_hash_result];
 485                 if(hash_table[hash_result] != -1) {
 486                         r_list[hash_table[hash_result]].hash_entry = hash_result;
 487                         time_info[r_list[hash_table[hash_result]].time_pos].position = hash_table[hash_result];
 488                 }
 489
 490 #ifdef DEBUG
 491                 if(debug) printk(KERN_INFO RECENT_NAME ": match(): Collision handled.\n");
 492 #endif
 493         }
 494
 495         if(hash_table[hash_result] == -1) {
 496 #ifdef DEBUG
 497                 if(debug) printk(KERN_INFO RECENT_NAME ": match(): New table entry. (hr: %d,ha: %u)\n",
 498                                  hash_result, addr);
 499 #endif
 500
 501                 /* New item found and IPT_RECENT_SET, so we need to add it */
 502                 location = time_info[curr_table->time_pos].position;
 503                 hash_table[r_list[location].hash_entry] = -1;
 504                 hash_table[hash_result] = location;
 505                 memset(r_list[location].last_pkts,0,ip_pkt_list_tot*sizeof(u_int32_t));
 506                 r_list[location].time_pos = curr_table->time_pos;
 507                 r_list[location].addr = addr;
 508                 r_list[location].ttl = ttl;
 509                 r_list[location].last_seen = now;
 510                 r_list[location].oldest_pkt = 1;
 511                 r_list[location].last_pkts[0] = now;
 512                 r_list[location].hash_entry = hash_result;
 513                 time_info[curr_table->time_pos].time = r_list[location].last_seen;
 514                 curr_table->time_pos = (curr_table->time_pos + 1) % ip_list_tot;
 515
 516                 ans = !info->invert;
 517         } else {
 518 #ifdef DEBUG
 519                 if(debug) printk(KERN_INFO RECENT_NAME ": match(): Existing table entry. (hr: %d,ha: %u)\n",
 520                                  hash_result,
 521                                  addr);
 522 #endif
 523
 524                 /* Existing item found */
 525                 location = hash_table[hash_result];
 526                 /* We have a match on address, now to make sure it meets all requirements for a
 527                  * full match. */
 528                 if(info->check_set & IPT_RECENT_CHECK || info->check_set & IPT_RECENT_UPDATE) {
 529                         if(!info->seconds && !info->hit_count) ans = !info->invert; else ans = info->invert;
 530                         if(info->seconds && !info->hit_count) {
 531                                 if(time_before_eq(now,r_list[location].last_seen+info->seconds*HZ)) ans = !info->invert; else ans = info->invert;
 532                         }
 533                         if(info->seconds && info->hit_count) {
 534                                 for(pkt_count = 0, hits_found = 0; pkt_count < ip_pkt_list_tot; pkt_count++) {
 535                                         if(time_before_eq(now,r_list[location].last_pkts[pkt_count]+info->seconds*HZ)) hits_found++;
 536                                 }
 537                                 if(hits_found >= info->hit_count) ans = !info->invert; else ans = info->invert;
 538                         }
 539                         if(info->hit_count && !info->seconds) {
 540                                 for(pkt_count = 0, hits_found = 0; pkt_count < ip_pkt_list_tot; pkt_count++) {
 541                                         if(r_list[location].last_pkts[pkt_count] == 0) break;
 542                                         hits_found++;
 543                                 }
 544                                 if(hits_found >= info->hit_count) ans = !info->invert; else ans = info->invert;
 545                         }
 546                 }
 547 #ifdef DEBUG
 548                 if(debug) {
 549                         if(ans)
 550                                 printk(KERN_INFO RECENT_NAME ": match(): match addr: %u\n",addr);
 551                         else
 552                                 printk(KERN_INFO RECENT_NAME ": match(): no match addr: %u\n",addr);
 553                 }
 554 #endif
 555
 556                 /* If and only if we have been asked to SET, or to UPDATE (on match) do we add the
 557                  * current timestamp to the last_seen. */
 558                 if((info->check_set & IPT_RECENT_SET && (ans = !info->invert)) || (info->check_set & IPT_RECENT_UPDATE && ans)) {
 559 #ifdef DEBUG
 560                         if(debug) printk(KERN_INFO RECENT_NAME ": match(): SET or UPDATE; updating time info.\n");
 561 #endif
 562                         /* Have to update our time info */
 563                         time_loc = r_list[location].time_pos;
 564                         time_info[time_loc].time = now;
 565                         time_info[time_loc].position = location;
 566                         while((time_info[(time_loc+1) % ip_list_tot].time < time_info[time_loc].time) && ((time_loc+1) % ip_list_tot) != curr_table->time_pos) {
 567                                 time_temp = time_info[time_loc].time;
 568                                 time_info[time_loc].time = time_info[(time_loc+1)%ip_list_tot].time;
 569                                 time_info[(time_loc+1)%ip_list_tot].time = time_temp;
 570                                 time_temp = time_info[time_loc].position;
 571                                 time_info[time_loc].position = time_info[(time_loc+1)%ip_list_tot].position;
 572                                 time_info[(time_loc+1)%ip_list_tot].position = time_temp;
 573                                 r_list[time_info[time_loc].position].time_pos = time_loc;
 574                                 r_list[time_info[(time_loc+1)%ip_list_tot].position].time_pos = (time_loc+1)%ip_list_tot;
 575                                 time_loc = (time_loc+1) % ip_list_tot;
 576                         }
 577                         r_list[location].time_pos = time_loc;
 578                         r_list[location].ttl = ttl;
 579                         r_list[location].last_pkts[r_list[location].oldest_pkt] = now;
 580                         r_list[location].oldest_pkt = ++r_list[location].oldest_pkt % ip_pkt_list_tot;
 581                         r_list[location].last_seen = now;
 582                 }
 583                 /* If we have been asked to remove the entry from the list, just set it to 0 */
 584                 if(info->check_set & IPT_RECENT_REMOVE) {
 585 #ifdef DEBUG
 586                         if(debug) printk(KERN_INFO RECENT_NAME ": match(): REMOVE; clearing entry (or: %d, hr: %d).\n",orig_hash_result,hash_result);
 587 #endif
 588                         /* Check if this is part of a collision chain */
 589                         while(hash_table[(orig_hash_result+1) % ip_list_hash_size] != -1) {
 590                                 orig_hash_result++;
 591                                 if(hash_func(r_list[hash_table[orig_hash_result]].addr,ip_list_hash_size) == hash_result) {
 592                                         /* Found collision chain, how deep does this rabbit hole go? */
 593 #ifdef DEBUG
 594                                         if(debug) printk(KERN_INFO RECENT_NAME ": match(): REMOVE; found collision chain.\n");
 595 #endif
 596                                         end_collision_chain = orig_hash_result;
 597                                 }
 598                         }
 599                         if(end_collision_chain != -1) {
 600 #ifdef DEBUG
 601                                 if(debug) printk(KERN_INFO RECENT_NAME ": match(): REMOVE; part of collision chain, moving to end.\n");
 602 #endif
 603                                 /* Part of a collision chain, swap it with the end of the chain
 604                                  * before removing. */
 605                                 r_list[hash_table[end_collision_chain]].hash_entry = hash_result;
 606                                 temp = hash_table[end_collision_chain];
 607                                 hash_table[end_collision_chain] = hash_table[hash_result];
 608                                 hash_table[hash_result] = temp;
 609                                 time_info[r_list[hash_table[hash_result]].time_pos].position = hash_table[hash_result];
 610                                 hash_result = end_collision_chain;
 611                                 r_list[hash_table[hash_result]].hash_entry = hash_result;
 612                                 time_info[r_list[hash_table[hash_result]].time_pos].position = hash_table[hash_result];
 613                         }
 614                         location = hash_table[hash_result];
 615                         hash_table[r_list[location].hash_entry] = -1;
 616                         time_loc = r_list[location].time_pos;
 617                         time_info[time_loc].time = 0;
 618                         time_info[time_loc].position = location;
 619                         while((time_info[(time_loc+1) % ip_list_tot].time < time_info[time_loc].time) && ((time_loc+1) % ip_list_tot) != curr_table->time_pos) {
 620                                 time_temp = time_info[time_loc].time;
 621                                 time_info[time_loc].time = time_info[(time_loc+1)%ip_list_tot].time;
 622                                 time_info[(time_loc+1)%ip_list_tot].time = time_temp;
 623                                 time_temp = time_info[time_loc].position;
 624                                 time_info[time_loc].position = time_info[(time_loc+1)%ip_list_tot].position;
 625                                 time_info[(time_loc+1)%ip_list_tot].position = time_temp;
 626                                 r_list[time_info[time_loc].position].time_pos = time_loc;
 627                                 r_list[time_info[(time_loc+1)%ip_list_tot].position].time_pos = (time_loc+1)%ip_list_tot;
 628                                 time_loc = (time_loc+1) % ip_list_tot;
 629                         }
 630                         r_list[location].time_pos = time_loc;
 631                         r_list[location].last_seen = 0;
 632                         r_list[location].addr = 0;
 633                         r_list[location].ttl = 0;
 634                         memset(r_list[location].last_pkts,0,ip_pkt_list_tot*sizeof(u_int32_t));
 635                         r_list[location].oldest_pkt = 0;
 636                         ans = !info->invert;
 637                 }
 638                 spin_unlock_bh(&curr_table->list_lock);
 639                 return ans;
 640         }
 641
 642         spin_unlock_bh(&curr_table->list_lock);
 643 #ifdef DEBUG
 644         if(debug) printk(KERN_INFO RECENT_NAME ": match() left.\n");
 645 #endif
 646         return ans;
 647 }
 648
 649 /* This function is to verify that the rule given during the userspace iptables
 650  * command is correct.
 651  * If the command is valid then we check if the table name referred to by the
 652  * rule exists, if not it is created.
 653  */
 654 static int
 655 checkentry(const char *tablename,
 656            const struct ipt_ip *ip,
 657            void *matchinfo,
 658            unsigned int matchsize,
 659            unsigned int hook_mask)
 660 {
 661         int flag = 0, c;
 662         unsigned long *hold;
 663         const struct ipt_recent_info *info = matchinfo;
 664         struct recent_ip_tables *curr_table, *find_table, *last_table;
 665
 666 #ifdef DEBUG
 667         if(debug) printk(KERN_INFO RECENT_NAME ": checkentry() entered.\n");
 668 #endif
 669
 670         if (matchsize != IPT_ALIGN(sizeof(struct ipt_recent_info))) return 0;
 671
 672         /* seconds and hit_count only valid for CHECK/UPDATE */
 673         if(info->check_set & IPT_RECENT_SET) { flag++; if(info->seconds || info->hit_count) return 0; }
 674         if(info->check_set & IPT_RECENT_REMOVE) { flag++; if(info->seconds || info->hit_count) return 0; }
 675         if(info->check_set & IPT_RECENT_CHECK) flag++;
 676         if(info->check_set & IPT_RECENT_UPDATE) flag++;
 677
 678         /* One and only one of these should ever be set */
 679         if(flag != 1) return 0;
 680
 681         /* Name must be set to something */
 682         if(!info->name || !info->name[0]) return 0;
 683
 684         /* Things look good, create a list for this if it does not exist */
 685         /* Lock the linked list while we play with it */
 686         spin_lock_bh(&recent_lock);
 687
 688         /* Look for an entry with this name already created */
 689         /* Finds the end of the list and the entry before the end if current name does not exist */
 690         find_table = r_tables;
 691         while( (last_table = find_table) && strncmp(info->name,find_table->name,IPT_RECENT_NAME_LEN) && (find_table = find_table->next) );
 692
 693         /* If a table already exists just increment the count on that table and return */
 694         if(find_table) {
 695 #ifdef DEBUG
 696                 if(debug) printk(KERN_INFO RECENT_NAME ": checkentry: table found (%s), incrementing count.\n",info->name);
 697 #endif
 698                 find_table->count++;
 699                 spin_unlock_bh(&recent_lock);
 700                 return 1;
 701         }
 702
 703         spin_unlock_bh(&recent_lock);
 704
 705         /* Table with this name not found */
 706         /* Allocate memory for new linked list item */
 707
 708 #ifdef DEBUG
 709         if(debug) {
 710                 printk(KERN_INFO RECENT_NAME ": checkentry: no table found (%s)\n",info->name);
 711                 printk(KERN_INFO RECENT_NAME ": checkentry: Allocationg %d for link-list entry.\n",sizeof(struct recent_ip_tables));
 712         }
 713 #endif
 714
 715         curr_table = vmalloc(sizeof(struct recent_ip_tables));
 716         if(curr_table == NULL) return 0;
 717
 718         spin_lock_init(&curr_table->list_lock);
 719         curr_table->next = NULL;
 720         curr_table->count = 1;
 721         curr_table->time_pos = 0;
 722         strncpy(curr_table->name,info->name,IPT_RECENT_NAME_LEN);
 723         curr_table->name[IPT_RECENT_NAME_LEN-1] = '\0';
 724
 725         /* Allocate memory for this table and the list of packets in each entry. */
 726 #ifdef DEBUG
 727         if(debug) printk(KERN_INFO RECENT_NAME ": checkentry: Allocating %d for table (%s).\n",
 728                         sizeof(struct recent_ip_list)*ip_list_tot,
 729                         info->name);
 730 #endif
 731
 732         curr_table->table = vmalloc(sizeof(struct recent_ip_list)*ip_list_tot);
 733         if(curr_table->table == NULL) { vfree(curr_table); return 0; }
 734         memset(curr_table->table,0,sizeof(struct recent_ip_list)*ip_list_tot);
 735 #ifdef DEBUG
 736         if(debug) printk(KERN_INFO RECENT_NAME ": checkentry: Allocating %d for pkt_list.\n",
 737                         sizeof(u_int32_t)*ip_pkt_list_tot*ip_list_tot);
 738 #endif
 739
 740         hold = vmalloc(sizeof(u_int32_t)*ip_pkt_list_tot*ip_list_tot);
 741 #ifdef DEBUG
 742         if(debug) printk(KERN_INFO RECENT_NAME ": checkentry: After pkt_list allocation.\n");
 743 #endif
 744         if(hold == NULL) {
 745                 printk(KERN_INFO RECENT_NAME ": checkentry: unable to allocate for pkt_list.\n");
 746                 vfree(curr_table->table);
 747                 vfree(curr_table);
 748                 return 0;
 749         }
 750         for(c = 0; c < ip_list_tot; c++) {
 751                 curr_table->table[c].last_pkts = hold + c*ip_pkt_list_tot;
 752         }
 753
 754         /* Allocate memory for the hash table */
 755 #ifdef DEBUG
 756         if(debug) printk(KERN_INFO RECENT_NAME ": checkentry: Allocating %d for hash_table.\n",
 757                         sizeof(int)*ip_list_hash_size);
 758 #endif
 759
 760         curr_table->hash_table = vmalloc(sizeof(int)*ip_list_hash_size);
 761         if(!curr_table->hash_table) {
 762                 printk(KERN_INFO RECENT_NAME ": checkentry: unable to allocate for hash_table.\n");
 763                 vfree(hold);
 764                 vfree(curr_table->table);
 765                 vfree(curr_table);
 766                 return 0;
 767         }
 768
 769         for(c = 0; c < ip_list_hash_size; c++) {
 770                 curr_table->hash_table[c] = -1;
 771         }
 772
 773         /* Allocate memory for the time info */
 774 #ifdef DEBUG
 775         if(debug) printk(KERN_INFO RECENT_NAME ": checkentry: Allocating %d for time_info.\n",
 776                         sizeof(struct time_info_list)*ip_list_tot);
 777 #endif
 778
 779         curr_table->time_info = vmalloc(sizeof(struct time_info_list)*ip_list_tot);
 780         if(!curr_table->time_info) {
 781                 printk(KERN_INFO RECENT_NAME ": checkentry: unable to allocate for time_info.\n");
 782                 vfree(curr_table->hash_table);
 783                 vfree(hold);
 784                 vfree(curr_table->table);
 785                 vfree(curr_table);
 786                 return 0;
 787         }
 788         for(c = 0; c < ip_list_tot; c++) {
 789                 curr_table->time_info[c].position = c;
 790                 curr_table->time_info[c].time = 0;
 791         }
 792
 793         /* Put the new table in place */
 794         spin_lock_bh(&recent_lock);
 795         find_table = r_tables;
 796         while( (last_table = find_table) && strncmp(info->name,find_table->name,IPT_RECENT_NAME_LEN) && (find_table = find_table->next) );
 797
 798         /* If a table already exists just increment the count on that table and return */
 799         if(find_table) {
 800                 find_table->count++;
 801                 spin_unlock_bh(&recent_lock);
 802 #ifdef DEBUG
 803                 if(debug) printk(KERN_INFO RECENT_NAME ": checkentry: table found (%s), created by other process.\n",info->name);
 804 #endif
 805                 vfree(curr_table->time_info);
 806                 vfree(curr_table->hash_table);
 807                 vfree(hold);
 808                 vfree(curr_table->table);
 809                 vfree(curr_table);
 810                 return 1;
 811         }
 812         if(!last_table) r_tables = curr_table; else last_table->next = curr_table;
 813
 814         spin_unlock_bh(&recent_lock);
 815
 816 #ifdef CONFIG_PROC_FS
 817         /* Create our proc 'status' entry. */
 818         curr_table->status_proc = create_proc_entry(curr_table->name, ip_list_perms, proc_net_ipt_recent);
 819         if (!curr_table->status_proc) {
 820                 printk(KERN_INFO RECENT_NAME ": checkentry: unable to allocate for /proc entry.\n");
 821                 /* Destroy the created table */
 822                 spin_lock_bh(&recent_lock);
 823                 last_table = NULL;
 824                 curr_table = r_tables;
 825                 if(!curr_table) {
 826 #ifdef DEBUG
 827                         if(debug) printk(KERN_INFO RECENT_NAME ": checkentry() create_proc failed, no tables.\n");
 828 #endif
 829                         spin_unlock_bh(&recent_lock);
 830                         return 0;
 831                 }
 832                 while( strncmp(info->name,curr_table->name,IPT_RECENT_NAME_LEN) && (last_table = curr_table) && (curr_table = curr_table->next) );
 833                 if(!curr_table) {
 834 #ifdef DEBUG
 835                         if(debug) printk(KERN_INFO RECENT_NAME ": checkentry() create_proc failed, table already destroyed.\n");
 836 #endif
 837                         spin_unlock_bh(&recent_lock);
 838                         return 0;
 839                 }
 840                 if(last_table) last_table->next = curr_table->next; else r_tables = curr_table->next;
 841                 spin_unlock_bh(&recent_lock);
 842                 vfree(curr_table->time_info);
 843                 vfree(curr_table->hash_table);
 844                 vfree(hold);
 845                 vfree(curr_table->table);
 846                 vfree(curr_table);
 847                 return 0;
 848         }
 849
 850         curr_table->status_proc->owner = THIS_MODULE;
 851         curr_table->status_proc->data = curr_table;
 852         wmb();
 853         curr_table->status_proc->read_proc = ip_recent_get_info;
 854         curr_table->status_proc->write_proc = ip_recent_ctrl;
 855 #endif /* CONFIG_PROC_FS */
 856
 857 #ifdef DEBUG
 858         if(debug) printk(KERN_INFO RECENT_NAME ": checkentry() left.\n");
 859 #endif
 860
 861         return 1;
 862 }
 863
 864 /* This function is called in the event that a rule matching this module is
 865  * removed.
 866  * When this happens we need to check if there are no other rules matching
 867  * the table given.  If that is the case then we remove the table and clean
 868  * up its memory.
 869  */
 870 static void
 871 destroy(void *matchinfo, unsigned int matchsize)
 872 {
 873         const struct ipt_recent_info *info = matchinfo;
 874         struct recent_ip_tables *curr_table, *last_table;
 875
 876 #ifdef DEBUG
 877         if(debug) printk(KERN_INFO RECENT_NAME ": destroy() entered.\n");
 878 #endif
 879
 880         if(matchsize != IPT_ALIGN(sizeof(struct ipt_recent_info))) return;
 881
 882         /* Lock the linked list while we play with it */
 883         spin_lock_bh(&recent_lock);
 884
 885         /* Look for an entry with this name already created */
 886         /* Finds the end of the list and the entry before the end if current name does not exist */
 887         last_table = NULL;
 888         curr_table = r_tables;
 889         if(!curr_table) {
 890 #ifdef DEBUG
 891                 if(debug) printk(KERN_INFO RECENT_NAME ": destroy() No tables found, leaving.\n");
 892 #endif
 893                 spin_unlock_bh(&recent_lock);
 894                 return;
 895         }
 896         while( strncmp(info->name,curr_table->name,IPT_RECENT_NAME_LEN) && (last_table = curr_table) && (curr_table = curr_table->next) );
 897
 898         /* If a table does not exist then do nothing and return */
 899         if(!curr_table) {
 900 #ifdef DEBUG
 901                 if(debug) printk(KERN_INFO RECENT_NAME ": destroy() table not found, leaving.\n");
 902 #endif
 903                 spin_unlock_bh(&recent_lock);
 904                 return;
 905         }
 906
 907         curr_table->count--;
 908
 909         /* If count is still non-zero then there are still rules referenceing it so we do nothing */
 910         if(curr_table->count) {
 911 #ifdef DEBUG
 912                 if(debug) printk(KERN_INFO RECENT_NAME ": destroy() table found, non-zero count, leaving.\n");
 913 #endif
 914                 spin_unlock_bh(&recent_lock);
 915                 return;
 916         }
 917
 918 #ifdef DEBUG
 919         if(debug) printk(KERN_INFO RECENT_NAME ": destroy() table found, zero count, removing.\n");
 920 #endif
 921
 922         /* Count must be zero so we remove this table from the list */
 923         if(last_table) last_table->next = curr_table->next; else r_tables = curr_table->next;
 924
 925         spin_unlock_bh(&recent_lock);
 926
 927         /* lock to make sure any late-runners still using this after we removed it from
 928          * the list finish up then remove everything */
 929         spin_lock_bh(&curr_table->list_lock);
 930         spin_unlock_bh(&curr_table->list_lock);
 931
 932 #ifdef CONFIG_PROC_FS
 933         if(curr_table->status_proc) remove_proc_entry(curr_table->name,proc_net_ipt_recent);
 934 #endif /* CONFIG_PROC_FS */
 935         vfree(curr_table->table[0].last_pkts);
 936         vfree(curr_table->table);
 937         vfree(curr_table->hash_table);
 938         vfree(curr_table->time_info);
 939         vfree(curr_table);
 940
 941 #ifdef DEBUG
 942         if(debug) printk(KERN_INFO RECENT_NAME ": destroy() left.\n");
 943 #endif
 944
 945         return;
 946 }
 947
 948 /* This is the structure we pass to ipt_register to register our
 949  * module with iptables.
 950  */
 951 static struct ipt_match recent_match = {
 952   .name = "recent",
 953   .match = &match,
 954   .checkentry = &checkentry,
 955   .destroy = &destroy,
 956   .me = THIS_MODULE
 957 };
 958
 959 /* Kernel module initialization. */
 960 static int __init init(void)
 961 {
 962         int err, count;
 963
 964         printk(version);
 965 #ifdef CONFIG_PROC_FS
 966         proc_net_ipt_recent = proc_mkdir("ipt_recent",proc_net);
 967         if(!proc_net_ipt_recent) return -ENOMEM;
 968 #endif
 969
 970         if(ip_list_hash_size && ip_list_hash_size <= ip_list_tot) {
 971           printk(KERN_WARNING RECENT_NAME ": ip_list_hash_size too small, resetting to default.\n");
 972           ip_list_hash_size = 0;
 973         }
 974
 975         if(!ip_list_hash_size) {
 976                 ip_list_hash_size = ip_list_tot*3;
 977                 count = 2*2;
 978                 while(ip_list_hash_size > count) count = count*2;
 979                 ip_list_hash_size = count;
 980         }
 981
 982 #ifdef DEBUG
 983         if(debug) printk(KERN_INFO RECENT_NAME ": ip_list_hash_size: %d\n",ip_list_hash_size);
 984 #endif
 985
 986         err = ipt_register_match(&recent_match);
 987         if (err)
 988                 remove_proc_entry("ipt_recent", proc_net);
 989         return err;
 990 }
 991
 992 /* Kernel module destruction. */
 993 static void __exit fini(void)
 994 {
 995         ipt_unregister_match(&recent_match);
 996
 997         remove_proc_entry("ipt_recent",proc_net);
 998 }
 999
1000 /* Register our module with the kernel. */
1001 module_init(init);
1002 module_exit(fini);