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14#include <linux/init.h>
15#include <linux/ip.h>
16#include <linux/moduleparam.h>
17#include <linux/proc_fs.h>
18#include <linux/seq_file.h>
19#include <linux/string.h>
20#include <linux/ctype.h>
21#include <linux/list.h>
22#include <linux/random.h>
23#include <linux/jhash.h>
24#include <linux/bitops.h>
25#include <linux/skbuff.h>
26#include <linux/inet.h>
27#include <net/net_namespace.h>
28
29#include <linux/netfilter/x_tables.h>
30#include <linux/netfilter_ipv4/ipt_recent.h>
31
32MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
33MODULE_DESCRIPTION("IP tables recently seen matching module");
34MODULE_LICENSE("GPL");
35
36static unsigned int ip_list_tot = 100;
37static unsigned int ip_pkt_list_tot = 20;
38static unsigned int ip_list_hash_size = 0;
39static unsigned int ip_list_perms = 0644;
40static unsigned int ip_list_uid = 0;
41static unsigned int ip_list_gid = 0;
42module_param(ip_list_tot, uint, 0400);
43module_param(ip_pkt_list_tot, uint, 0400);
44module_param(ip_list_hash_size, uint, 0400);
45module_param(ip_list_perms, uint, 0400);
46module_param(ip_list_uid, uint, 0400);
47module_param(ip_list_gid, uint, 0400);
48MODULE_PARM_DESC(ip_list_tot, "number of IPs to remember per list");
49MODULE_PARM_DESC(ip_pkt_list_tot, "number of packets per IP to remember (max. 255)");
50MODULE_PARM_DESC(ip_list_hash_size, "size of hash table used to look up IPs");
51MODULE_PARM_DESC(ip_list_perms, "permissions on /proc/net/ipt_recent/* files");
52MODULE_PARM_DESC(ip_list_uid,"owner of /proc/net/ipt_recent/* files");
53MODULE_PARM_DESC(ip_list_gid,"owning group of /proc/net/ipt_recent/* files");
54
55struct recent_entry {
56 struct list_head list;
57 struct list_head lru_list;
58 __be32 addr;
59 u_int8_t ttl;
60 u_int8_t index;
61 u_int16_t nstamps;
62 unsigned long stamps[0];
63};
64
65struct recent_table {
66 struct list_head list;
67 char name[IPT_RECENT_NAME_LEN];
68#ifdef CONFIG_PROC_FS
69 struct proc_dir_entry *proc;
70#endif
71 unsigned int refcnt;
72 unsigned int entries;
73 struct list_head lru_list;
74 struct list_head iphash[0];
75};
76
77static LIST_HEAD(tables);
78static DEFINE_SPINLOCK(recent_lock);
79static DEFINE_MUTEX(recent_mutex);
80
81#ifdef CONFIG_PROC_FS
82static struct proc_dir_entry *proc_dir;
83static const struct file_operations recent_fops;
84#endif
85
86static u_int32_t hash_rnd;
87static int hash_rnd_initted;
88
89static unsigned int recent_entry_hash(__be32 addr)
90{
91 if (!hash_rnd_initted) {
92 get_random_bytes(&hash_rnd, 4);
93 hash_rnd_initted = 1;
94 }
95 return jhash_1word((__force u32)addr, hash_rnd) & (ip_list_hash_size - 1);
96}
97
98static struct recent_entry *
99recent_entry_lookup(const struct recent_table *table, __be32 addr, u_int8_t ttl)
100{
101 struct recent_entry *e;
102 unsigned int h;
103
104 h = recent_entry_hash(addr);
105 list_for_each_entry(e, &table->iphash[h], list)
106 if (e->addr == addr && (ttl == e->ttl || !ttl || !e->ttl))
107 return e;
108 return NULL;
109}
110
111static void recent_entry_remove(struct recent_table *t, struct recent_entry *e)
112{
113 list_del(&e->list);
114 list_del(&e->lru_list);
115 kfree(e);
116 t->entries--;
117}
118
119static struct recent_entry *
120recent_entry_init(struct recent_table *t, __be32 addr, u_int8_t ttl)
121{
122 struct recent_entry *e;
123
124 if (t->entries >= ip_list_tot) {
125 e = list_entry(t->lru_list.next, struct recent_entry, lru_list);
126 recent_entry_remove(t, e);
127 }
128 e = kmalloc(sizeof(*e) + sizeof(e->stamps[0]) * ip_pkt_list_tot,
129 GFP_ATOMIC);
130 if (e == NULL)
131 return NULL;
132 e->addr = addr;
133 e->ttl = ttl;
134 e->stamps[0] = jiffies;
135 e->nstamps = 1;
136 e->index = 1;
137 list_add_tail(&e->list, &t->iphash[recent_entry_hash(addr)]);
138 list_add_tail(&e->lru_list, &t->lru_list);
139 t->entries++;
140 return e;
141}
142
143static void recent_entry_update(struct recent_table *t, struct recent_entry *e)
144{
145 e->stamps[e->index++] = jiffies;
146 if (e->index > e->nstamps)
147 e->nstamps = e->index;
148 e->index %= ip_pkt_list_tot;
149 list_move_tail(&e->lru_list, &t->lru_list);
150}
151
152static struct recent_table *recent_table_lookup(const char *name)
153{
154 struct recent_table *t;
155
156 list_for_each_entry(t, &tables, list)
157 if (!strcmp(t->name, name))
158 return t;
159 return NULL;
160}
161
162static void recent_table_flush(struct recent_table *t)
163{
164 struct recent_entry *e, *next;
165 unsigned int i;
166
167 for (i = 0; i < ip_list_hash_size; i++)
168 list_for_each_entry_safe(e, next, &t->iphash[i], list)
169 recent_entry_remove(t, e);
170}
171
172static bool
173ipt_recent_match(const struct sk_buff *skb,
174 const struct net_device *in, const struct net_device *out,
175 const struct xt_match *match, const void *matchinfo,
176 int offset, unsigned int protoff, bool *hotdrop)
177{
178 const struct ipt_recent_info *info = matchinfo;
179 struct recent_table *t;
180 struct recent_entry *e;
181 __be32 addr;
182 u_int8_t ttl;
183 bool ret = info->invert;
184
185 if (info->side == IPT_RECENT_DEST)
186 addr = ip_hdr(skb)->daddr;
187 else
188 addr = ip_hdr(skb)->saddr;
189
190 ttl = ip_hdr(skb)->ttl;
191
192 if (out && !skb->sk)
193 ttl++;
194
195 spin_lock_bh(&recent_lock);
196 t = recent_table_lookup(info->name);
197 e = recent_entry_lookup(t, addr,
198 info->check_set & IPT_RECENT_TTL ? ttl : 0);
199 if (e == NULL) {
200 if (!(info->check_set & IPT_RECENT_SET))
201 goto out;
202 e = recent_entry_init(t, addr, ttl);
203 if (e == NULL)
204 *hotdrop = true;
205 ret = !ret;
206 goto out;
207 }
208
209 if (info->check_set & IPT_RECENT_SET)
210 ret = !ret;
211 else if (info->check_set & IPT_RECENT_REMOVE) {
212 recent_entry_remove(t, e);
213 ret = !ret;
214 } else if (info->check_set & (IPT_RECENT_CHECK | IPT_RECENT_UPDATE)) {
215 unsigned long t = jiffies - info->seconds * HZ;
216 unsigned int i, hits = 0;
217
218 for (i = 0; i < e->nstamps; i++) {
219 if (info->seconds && time_after(t, e->stamps[i]))
220 continue;
221 if (++hits >= info->hit_count) {
222 ret = !ret;
223 break;
224 }
225 }
226 }
227
228 if (info->check_set & IPT_RECENT_SET ||
229 (info->check_set & IPT_RECENT_UPDATE && ret)) {
230 recent_entry_update(t, e);
231 e->ttl = ttl;
232 }
233out:
234 spin_unlock_bh(&recent_lock);
235 return ret;
236}
237
238static bool
239ipt_recent_checkentry(const char *tablename, const void *ip,
240 const struct xt_match *match, void *matchinfo,
241 unsigned int hook_mask)
242{
243 const struct ipt_recent_info *info = matchinfo;
244 struct recent_table *t;
245 unsigned i;
246 bool ret = false;
247
248 if (hweight8(info->check_set &
249 (IPT_RECENT_SET | IPT_RECENT_REMOVE |
250 IPT_RECENT_CHECK | IPT_RECENT_UPDATE)) != 1)
251 return false;
252 if ((info->check_set & (IPT_RECENT_SET | IPT_RECENT_REMOVE)) &&
253 (info->seconds || info->hit_count))
254 return false;
255 if (info->name[0] == '\0' ||
256 strnlen(info->name, IPT_RECENT_NAME_LEN) == IPT_RECENT_NAME_LEN)
257 return false;
258
259 mutex_lock(&recent_mutex);
260 t = recent_table_lookup(info->name);
261 if (t != NULL) {
262 t->refcnt++;
263 ret = true;
264 goto out;
265 }
266
267 t = kzalloc(sizeof(*t) + sizeof(t->iphash[0]) * ip_list_hash_size,
268 GFP_KERNEL);
269 if (t == NULL)
270 goto out;
271 t->refcnt = 1;
272 strcpy(t->name, info->name);
273 INIT_LIST_HEAD(&t->lru_list);
274 for (i = 0; i < ip_list_hash_size; i++)
275 INIT_LIST_HEAD(&t->iphash[i]);
276#ifdef CONFIG_PROC_FS
277 t->proc = create_proc_entry(t->name, ip_list_perms, proc_dir);
278 if (t->proc == NULL) {
279 kfree(t);
280 goto out;
281 }
282 t->proc->proc_fops = &recent_fops;
283 t->proc->uid = ip_list_uid;
284 t->proc->gid = ip_list_gid;
285 t->proc->data = t;
286#endif
287 spin_lock_bh(&recent_lock);
288 list_add_tail(&t->list, &tables);
289 spin_unlock_bh(&recent_lock);
290 ret = true;
291out:
292 mutex_unlock(&recent_mutex);
293 return ret;
294}
295
296static void
297ipt_recent_destroy(const struct xt_match *match, void *matchinfo)
298{
299 const struct ipt_recent_info *info = matchinfo;
300 struct recent_table *t;
301
302 mutex_lock(&recent_mutex);
303 t = recent_table_lookup(info->name);
304 if (--t->refcnt == 0) {
305 spin_lock_bh(&recent_lock);
306 list_del(&t->list);
307 spin_unlock_bh(&recent_lock);
308 recent_table_flush(t);
309#ifdef CONFIG_PROC_FS
310 remove_proc_entry(t->name, proc_dir);
311#endif
312 kfree(t);
313 }
314 mutex_unlock(&recent_mutex);
315}
316
317#ifdef CONFIG_PROC_FS
318struct recent_iter_state {
319 struct recent_table *table;
320 unsigned int bucket;
321};
322
323static void *recent_seq_start(struct seq_file *seq, loff_t *pos)
324{
325 struct recent_iter_state *st = seq->private;
326 const struct recent_table *t = st->table;
327 struct recent_entry *e;
328 loff_t p = *pos;
329
330 spin_lock_bh(&recent_lock);
331
332 for (st->bucket = 0; st->bucket < ip_list_hash_size; st->bucket++)
333 list_for_each_entry(e, &t->iphash[st->bucket], list)
334 if (p-- == 0)
335 return e;
336 return NULL;
337}
338
339static void *recent_seq_next(struct seq_file *seq, void *v, loff_t *pos)
340{
341 struct recent_iter_state *st = seq->private;
342 struct recent_table *t = st->table;
343 struct recent_entry *e = v;
344 struct list_head *head = e->list.next;
345
346 while (head == &t->iphash[st->bucket]) {
347 if (++st->bucket >= ip_list_hash_size)
348 return NULL;
349 head = t->iphash[st->bucket].next;
350 }
351 (*pos)++;
352 return list_entry(head, struct recent_entry, list);
353}
354
355static void recent_seq_stop(struct seq_file *s, void *v)
356{
357 spin_unlock_bh(&recent_lock);
358}
359
360static int recent_seq_show(struct seq_file *seq, void *v)
361{
362 struct recent_entry *e = v;
363 unsigned int i;
364
365 i = (e->index - 1) % ip_pkt_list_tot;
366 seq_printf(seq, "src=%u.%u.%u.%u ttl: %u last_seen: %lu oldest_pkt: %u",
367 NIPQUAD(e->addr), e->ttl, e->stamps[i], e->index);
368 for (i = 0; i < e->nstamps; i++)
369 seq_printf(seq, "%s %lu", i ? "," : "", e->stamps[i]);
370 seq_printf(seq, "\n");
371 return 0;
372}
373
374static const struct seq_operations recent_seq_ops = {
375 .start = recent_seq_start,
376 .next = recent_seq_next,
377 .stop = recent_seq_stop,
378 .show = recent_seq_show,
379};
380
381static int recent_seq_open(struct inode *inode, struct file *file)
382{
383 struct proc_dir_entry *pde = PDE(inode);
384 struct recent_iter_state *st;
385
386 st = __seq_open_private(file, &recent_seq_ops, sizeof(*st));
387 if (st == NULL)
388 return -ENOMEM;
389
390 st->table = pde->data;
391 return 0;
392}
393
394static ssize_t recent_proc_write(struct file *file, const char __user *input,
395 size_t size, loff_t *loff)
396{
397 struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
398 struct recent_table *t = pde->data;
399 struct recent_entry *e;
400 char buf[sizeof("+255.255.255.255")], *c = buf;
401 __be32 addr;
402 int add;
403
404 if (size > sizeof(buf))
405 size = sizeof(buf);
406 if (copy_from_user(buf, input, size))
407 return -EFAULT;
408 while (isspace(*c))
409 c++;
410
411 if (size - (c - buf) < 5)
412 return c - buf;
413 if (!strncmp(c, "clear", 5)) {
414 c += 5;
415 spin_lock_bh(&recent_lock);
416 recent_table_flush(t);
417 spin_unlock_bh(&recent_lock);
418 return c - buf;
419 }
420
421 switch (*c) {
422 case '-':
423 add = 0;
424 c++;
425 break;
426 case '+':
427 c++;
428 default:
429 add = 1;
430 break;
431 }
432 addr = in_aton(c);
433
434 spin_lock_bh(&recent_lock);
435 e = recent_entry_lookup(t, addr, 0);
436 if (e == NULL) {
437 if (add)
438 recent_entry_init(t, addr, 0);
439 } else {
440 if (add)
441 recent_entry_update(t, e);
442 else
443 recent_entry_remove(t, e);
444 }
445 spin_unlock_bh(&recent_lock);
446 return size;
447}
448
449static const struct file_operations recent_fops = {
450 .open = recent_seq_open,
451 .read = seq_read,
452 .write = recent_proc_write,
453 .release = seq_release_private,
454 .owner = THIS_MODULE,
455};
456#endif
457
458static struct xt_match recent_match __read_mostly = {
459 .name = "recent",
460 .family = AF_INET,
461 .match = ipt_recent_match,
462 .matchsize = sizeof(struct ipt_recent_info),
463 .checkentry = ipt_recent_checkentry,
464 .destroy = ipt_recent_destroy,
465 .me = THIS_MODULE,
466};
467
468static int __init ipt_recent_init(void)
469{
470 int err;
471
472 if (!ip_list_tot || !ip_pkt_list_tot || ip_pkt_list_tot > 255)
473 return -EINVAL;
474 ip_list_hash_size = 1 << fls(ip_list_tot);
475
476 err = xt_register_match(&recent_match);
477#ifdef CONFIG_PROC_FS
478 if (err)
479 return err;
480 proc_dir = proc_mkdir("ipt_recent", init_net.proc_net);
481 if (proc_dir == NULL) {
482 xt_unregister_match(&recent_match);
483 err = -ENOMEM;
484 }
485#endif
486 return err;
487}
488
489static void __exit ipt_recent_exit(void)
490{
491 BUG_ON(!list_empty(&tables));
492 xt_unregister_match(&recent_match);
493#ifdef CONFIG_PROC_FS
494 remove_proc_entry("ipt_recent", init_net.proc_net);
495#endif
496}
497
498module_init(ipt_recent_init);
499module_exit(ipt_recent_exit);
500
