2 * count the number of connections matching an arbitrary key.
4 * (C) 2017 Red Hat GmbH
5 * Author: Florian Westphal <fw@strlen.de>
7 * split from xt_connlimit.c:
8 * (c) 2000 Gerd Knorr <kraxel@bytesex.org>
9 * Nov 2002: Martin Bene <martin.bene@icomedias.com>:
10 * only ignore TIME_WAIT or gone connections
11 * (C) CC Computer Consultants GmbH, 2007
13 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
15 #include <linux/in6.h>
17 #include <linux/ipv6.h>
18 #include <linux/jhash.h>
19 #include <linux/slab.h>
20 #include <linux/list.h>
21 #include <linux/rbtree.h>
22 #include <linux/module.h>
23 #include <linux/random.h>
24 #include <linux/skbuff.h>
25 #include <linux/spinlock.h>
26 #include <linux/netfilter/nf_conntrack_tcp.h>
27 #include <linux/netfilter/x_tables.h>
28 #include <net/netfilter/nf_conntrack.h>
29 #include <net/netfilter/nf_conntrack_count.h>
30 #include <net/netfilter/nf_conntrack_core.h>
31 #include <net/netfilter/nf_conntrack_tuple.h>
32 #include <net/netfilter/nf_conntrack_zones.h>
34 #define CONNCOUNT_SLOTS 256U
37 #define CONNCOUNT_LOCK_SLOTS 8U
39 #define CONNCOUNT_LOCK_SLOTS 256U
42 #define CONNCOUNT_GC_MAX_NODES 8
45 /* we will save the tuples of all connections we care about */
46 struct nf_conncount_tuple {
47 struct hlist_node node;
48 struct nf_conntrack_tuple tuple;
51 struct nf_conncount_rb {
53 struct hlist_head hhead; /* connections/hosts in same subnet */
57 static spinlock_t nf_conncount_locks[CONNCOUNT_LOCK_SLOTS] __cacheline_aligned_in_smp;
59 struct nf_conncount_data {
61 struct rb_root root[CONNCOUNT_SLOTS];
64 static u_int32_t conncount_rnd __read_mostly;
65 static struct kmem_cache *conncount_rb_cachep __read_mostly;
66 static struct kmem_cache *conncount_conn_cachep __read_mostly;
68 static inline bool already_closed(const struct nf_conn *conn)
70 if (nf_ct_protonum(conn) == IPPROTO_TCP)
71 return conn->proto.tcp.state == TCP_CONNTRACK_TIME_WAIT ||
72 conn->proto.tcp.state == TCP_CONNTRACK_CLOSE;
77 static int key_diff(const u32 *a, const u32 *b, unsigned int klen)
79 return memcmp(a, b, klen * sizeof(u32));
82 static bool add_hlist(struct hlist_head *head,
83 const struct nf_conntrack_tuple *tuple)
85 struct nf_conncount_tuple *conn;
87 conn = kmem_cache_alloc(conncount_conn_cachep, GFP_ATOMIC);
91 hlist_add_head(&conn->node, head);
95 static unsigned int check_hlist(struct net *net,
96 struct hlist_head *head,
97 const struct nf_conntrack_tuple *tuple,
98 const struct nf_conntrack_zone *zone,
101 const struct nf_conntrack_tuple_hash *found;
102 struct nf_conncount_tuple *conn;
103 struct hlist_node *n;
104 struct nf_conn *found_ct;
105 unsigned int length = 0;
107 *addit = tuple ? true : false;
109 /* check the saved connections */
110 hlist_for_each_entry_safe(conn, n, head, node) {
111 found = nf_conntrack_find_get(net, zone, &conn->tuple);
113 hlist_del(&conn->node);
114 kmem_cache_free(conncount_conn_cachep, conn);
118 found_ct = nf_ct_tuplehash_to_ctrack(found);
120 if (tuple && nf_ct_tuple_equal(&conn->tuple, tuple)) {
122 * Just to be sure we have it only once in the list.
123 * We should not see tuples twice unless someone hooks
124 * this into a table without "-p tcp --syn".
127 } else if (already_closed(found_ct)) {
129 * we do not care about connections which are
130 * closed already -> ditch it
133 hlist_del(&conn->node);
134 kmem_cache_free(conncount_conn_cachep, conn);
145 static void tree_nodes_free(struct rb_root *root,
146 struct nf_conncount_rb *gc_nodes[],
147 unsigned int gc_count)
149 struct nf_conncount_rb *rbconn;
152 rbconn = gc_nodes[--gc_count];
153 rb_erase(&rbconn->node, root);
154 kmem_cache_free(conncount_rb_cachep, rbconn);
159 count_tree(struct net *net, struct rb_root *root,
160 const u32 *key, u8 keylen,
161 const struct nf_conntrack_tuple *tuple,
162 const struct nf_conntrack_zone *zone)
164 struct nf_conncount_rb *gc_nodes[CONNCOUNT_GC_MAX_NODES];
165 struct rb_node **rbnode, *parent;
166 struct nf_conncount_rb *rbconn;
167 struct nf_conncount_tuple *conn;
168 unsigned int gc_count;
174 rbnode = &(root->rb_node);
179 rbconn = rb_entry(*rbnode, struct nf_conncount_rb, node);
182 diff = key_diff(key, rbconn->key, keylen);
184 rbnode = &((*rbnode)->rb_left);
185 } else if (diff > 0) {
186 rbnode = &((*rbnode)->rb_right);
188 /* same source network -> be counted! */
190 count = check_hlist(net, &rbconn->hhead, tuple, zone, &addit);
192 tree_nodes_free(root, gc_nodes, gc_count);
196 if (!add_hlist(&rbconn->hhead, tuple))
197 return 0; /* hotdrop */
202 if (no_gc || gc_count >= ARRAY_SIZE(gc_nodes))
205 /* only used for GC on hhead, retval and 'addit' ignored */
206 check_hlist(net, &rbconn->hhead, tuple, zone, &addit);
207 if (hlist_empty(&rbconn->hhead))
208 gc_nodes[gc_count++] = rbconn;
213 tree_nodes_free(root, gc_nodes, gc_count);
214 /* tree_node_free before new allocation permits
215 * allocator to re-use newly free'd object.
217 * This is a rare event; in most cases we will find
218 * existing node to re-use. (or gc_count is 0).
226 /* no match, need to insert new node */
227 rbconn = kmem_cache_alloc(conncount_rb_cachep, GFP_ATOMIC);
231 conn = kmem_cache_alloc(conncount_conn_cachep, GFP_ATOMIC);
233 kmem_cache_free(conncount_rb_cachep, rbconn);
237 conn->tuple = *tuple;
238 memcpy(rbconn->key, key, sizeof(u32) * keylen);
240 INIT_HLIST_HEAD(&rbconn->hhead);
241 hlist_add_head(&conn->node, &rbconn->hhead);
243 rb_link_node(&rbconn->node, parent, rbnode);
244 rb_insert_color(&rbconn->node, root);
248 /* Count and return number of conntrack entries in 'net' with particular 'key'.
249 * If 'tuple' is not null, insert it into the accounting data structure.
251 unsigned int nf_conncount_count(struct net *net,
252 struct nf_conncount_data *data,
254 const struct nf_conntrack_tuple *tuple,
255 const struct nf_conntrack_zone *zone)
257 struct rb_root *root;
261 hash = jhash2(key, data->keylen, conncount_rnd) % CONNCOUNT_SLOTS;
262 root = &data->root[hash];
264 spin_lock_bh(&nf_conncount_locks[hash % CONNCOUNT_LOCK_SLOTS]);
266 count = count_tree(net, root, key, data->keylen, tuple, zone);
268 spin_unlock_bh(&nf_conncount_locks[hash % CONNCOUNT_LOCK_SLOTS]);
272 EXPORT_SYMBOL_GPL(nf_conncount_count);
274 struct nf_conncount_data *nf_conncount_init(struct net *net, unsigned int family,
277 struct nf_conncount_data *data;
280 if (keylen % sizeof(u32) ||
281 keylen / sizeof(u32) > MAX_KEYLEN ||
283 return ERR_PTR(-EINVAL);
285 net_get_random_once(&conncount_rnd, sizeof(conncount_rnd));
287 data = kmalloc(sizeof(*data), GFP_KERNEL);
289 return ERR_PTR(-ENOMEM);
291 ret = nf_ct_netns_get(net, family);
297 for (i = 0; i < ARRAY_SIZE(data->root); ++i)
298 data->root[i] = RB_ROOT;
300 data->keylen = keylen / sizeof(u32);
304 EXPORT_SYMBOL_GPL(nf_conncount_init);
306 static void destroy_tree(struct rb_root *r)
308 struct nf_conncount_tuple *conn;
309 struct nf_conncount_rb *rbconn;
310 struct hlist_node *n;
311 struct rb_node *node;
313 while ((node = rb_first(r)) != NULL) {
314 rbconn = rb_entry(node, struct nf_conncount_rb, node);
318 hlist_for_each_entry_safe(conn, n, &rbconn->hhead, node)
319 kmem_cache_free(conncount_conn_cachep, conn);
321 kmem_cache_free(conncount_rb_cachep, rbconn);
325 void nf_conncount_destroy(struct net *net, unsigned int family,
326 struct nf_conncount_data *data)
330 nf_ct_netns_put(net, family);
332 for (i = 0; i < ARRAY_SIZE(data->root); ++i)
333 destroy_tree(&data->root[i]);
337 EXPORT_SYMBOL_GPL(nf_conncount_destroy);
339 static int __init nf_conncount_modinit(void)
343 BUILD_BUG_ON(CONNCOUNT_LOCK_SLOTS > CONNCOUNT_SLOTS);
344 BUILD_BUG_ON((CONNCOUNT_SLOTS % CONNCOUNT_LOCK_SLOTS) != 0);
346 for (i = 0; i < CONNCOUNT_LOCK_SLOTS; ++i)
347 spin_lock_init(&nf_conncount_locks[i]);
349 conncount_conn_cachep = kmem_cache_create("nf_conncount_tuple",
350 sizeof(struct nf_conncount_tuple),
352 if (!conncount_conn_cachep)
355 conncount_rb_cachep = kmem_cache_create("nf_conncount_rb",
356 sizeof(struct nf_conncount_rb),
358 if (!conncount_rb_cachep) {
359 kmem_cache_destroy(conncount_conn_cachep);
366 static void __exit nf_conncount_modexit(void)
368 kmem_cache_destroy(conncount_conn_cachep);
369 kmem_cache_destroy(conncount_rb_cachep);
372 module_init(nf_conncount_modinit);
373 module_exit(nf_conncount_modexit);
374 MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
375 MODULE_AUTHOR("Florian Westphal <fw@strlen.de>");
376 MODULE_DESCRIPTION("netfilter: count number of connections matching a key");
377 MODULE_LICENSE("GPL");