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/*
* count the number of connections matching an arbitrary key.
*
* (C) 2017 Red Hat GmbH
* Author: Florian Westphal <fw@strlen.de>
*
* split from xt_connlimit.c:
* (c) 2000 Gerd Knorr <kraxel@bytesex.org>
* Nov 2002: Martin Bene <martin.bene@icomedias.com>:
* only ignore TIME_WAIT or gone connections
* (C) CC Computer Consultants GmbH, 2007
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/in.h>
#include <linux/in6.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/jhash.h>
#include <linux/slab.h>
#include <linux/list.h>
#include <linux/rbtree.h>
#include <linux/module.h>
#include <linux/random.h>
#include <linux/skbuff.h>
#include <linux/spinlock.h>
#include <linux/netfilter/nf_conntrack_tcp.h>
#include <linux/netfilter/x_tables.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_count.h>
#include <net/netfilter/nf_conntrack_core.h>
#include <net/netfilter/nf_conntrack_tuple.h>
#include <net/netfilter/nf_conntrack_zones.h>
#define CONNCOUNT_SLOTS 256U
#ifdef CONFIG_LOCKDEP
#define CONNCOUNT_LOCK_SLOTS 8U
#else
#define CONNCOUNT_LOCK_SLOTS 256U
#endif
#define CONNCOUNT_GC_MAX_NODES 8
#define MAX_KEYLEN 5
/* we will save the tuples of all connections we care about */
struct nf_conncount_tuple {
struct hlist_node node;
struct nf_conntrack_tuple tuple;
struct nf_conntrack_zone zone;
int cpu;
u32 jiffies32;
};
struct nf_conncount_rb {
struct rb_node node;
struct hlist_head hhead; /* connections/hosts in same subnet */
u32 key[MAX_KEYLEN];
};
static spinlock_t nf_conncount_locks[CONNCOUNT_LOCK_SLOTS] __cacheline_aligned_in_smp;
struct nf_conncount_data {
unsigned int keylen;
struct rb_root root[CONNCOUNT_SLOTS];
};
static u_int32_t conncount_rnd __read_mostly;
static struct kmem_cache *conncount_rb_cachep __read_mostly;
static struct kmem_cache *conncount_conn_cachep __read_mostly;
static inline bool already_closed(const struct nf_conn *conn)
{
if (nf_ct_protonum(conn) == IPPROTO_TCP)
return conn->proto.tcp.state == TCP_CONNTRACK_TIME_WAIT ||
conn->proto.tcp.state == TCP_CONNTRACK_CLOSE;
else
return false;
}
static int key_diff(const u32 *a, const u32 *b, unsigned int klen)
{
return memcmp(a, b, klen * sizeof(u32));
}
bool nf_conncount_add(struct hlist_head *head,
const struct nf_conntrack_tuple *tuple,
const struct nf_conntrack_zone *zone)
{
struct nf_conncount_tuple *conn;
conn = kmem_cache_alloc(conncount_conn_cachep, GFP_ATOMIC);
if (conn == NULL)
return false;
conn->tuple = *tuple;
conn->zone = *zone;
conn->cpu = raw_smp_processor_id();
conn->jiffies32 = (u32)jiffies;
hlist_add_head(&conn->node, head);
return true;
}
EXPORT_SYMBOL_GPL(nf_conncount_add);
static const struct nf_conntrack_tuple_hash *
find_or_evict(struct net *net, struct nf_conncount_tuple *conn)
{
const struct nf_conntrack_tuple_hash *found;
unsigned long a, b;
int cpu = raw_smp_processor_id();
__s32 age;
found = nf_conntrack_find_get(net, &conn->zone, &conn->tuple);
if (found)
return found;
b = conn->jiffies32;
a = (u32)jiffies;
/* conn might have been added just before by another cpu and
* might still be unconfirmed. In this case, nf_conntrack_find()
* returns no result. Thus only evict if this cpu added the
* stale entry or if the entry is older than two jiffies.
*/
age = a - b;
if (conn->cpu == cpu || age >= 2) {
hlist_del(&conn->node);
kmem_cache_free(conncount_conn_cachep, conn);
return ERR_PTR(-ENOENT);
}
return ERR_PTR(-EAGAIN);
}
unsigned int nf_conncount_lookup(struct net *net, struct hlist_head *head,
const struct nf_conntrack_tuple *tuple,
const struct nf_conntrack_zone *zone,
bool *addit)
{
const struct nf_conntrack_tuple_hash *found;
struct nf_conncount_tuple *conn;
struct nf_conn *found_ct;
struct hlist_node *n;
unsigned int length = 0;
*addit = tuple ? true : false;
/* check the saved connections */
hlist_for_each_entry_safe(conn, n, head, node) {
found = find_or_evict(net, conn);
if (IS_ERR(found)) {
/* Not found, but might be about to be confirmed */
if (PTR_ERR(found) == -EAGAIN) {
length++;
if (!tuple)
continue;
if (nf_ct_tuple_equal(&conn->tuple, tuple) &&
nf_ct_zone_id(&conn->zone, conn->zone.dir) ==
nf_ct_zone_id(zone, zone->dir))
*addit = false;
}
continue;
}
found_ct = nf_ct_tuplehash_to_ctrack(found);
if (tuple && nf_ct_tuple_equal(&conn->tuple, tuple) &&
nf_ct_zone_equal(found_ct, zone, zone->dir)) {
/*
* Just to be sure we have it only once in the list.
* We should not see tuples twice unless someone hooks
* this into a table without "-p tcp --syn".
*/
*addit = false;
} else if (already_closed(found_ct)) {
/*
* we do not care about connections which are
* closed already -> ditch it
*/
nf_ct_put(found_ct);
hlist_del(&conn->node);
kmem_cache_free(conncount_conn_cachep, conn);
continue;
}
nf_ct_put(found_ct);
length++;
}
return length;
}
EXPORT_SYMBOL_GPL(nf_conncount_lookup);
static void tree_nodes_free(struct rb_root *root,
struct nf_conncount_rb *gc_nodes[],
unsigned int gc_count)
{
struct nf_conncount_rb *rbconn;
while (gc_count) {
rbconn = gc_nodes[--gc_count];
rb_erase(&rbconn->node, root);
kmem_cache_free(conncount_rb_cachep, rbconn);
}
}
static unsigned int
count_tree(struct net *net, struct rb_root *root,
const u32 *key, u8 keylen,
const struct nf_conntrack_tuple *tuple,
const struct nf_conntrack_zone *zone)
{
struct nf_conncount_rb *gc_nodes[CONNCOUNT_GC_MAX_NODES];
struct rb_node **rbnode, *parent;
struct nf_conncount_rb *rbconn;
struct nf_conncount_tuple *conn;
unsigned int gc_count;
bool no_gc = false;
restart:
gc_count = 0;
parent = NULL;
rbnode = &(root->rb_node);
while (*rbnode) {
int diff;
bool addit;
rbconn = rb_entry(*rbnode, struct nf_conncount_rb, node);
parent = *rbnode;
diff = key_diff(key, rbconn->key, keylen);
if (diff < 0) {
rbnode = &((*rbnode)->rb_left);
} else if (diff > 0) {
rbnode = &((*rbnode)->rb_right);
} else {
/* same source network -> be counted! */
unsigned int count;
count = nf_conncount_lookup(net, &rbconn->hhead, tuple,
zone, &addit);
tree_nodes_free(root, gc_nodes, gc_count);
if (!addit)
return count;
if (!nf_conncount_add(&rbconn->hhead, tuple, zone))
return 0; /* hotdrop */
return count + 1;
}
if (no_gc || gc_count >= ARRAY_SIZE(gc_nodes))
continue;
/* only used for GC on hhead, retval and 'addit' ignored */
nf_conncount_lookup(net, &rbconn->hhead, tuple, zone, &addit);
if (hlist_empty(&rbconn->hhead))
gc_nodes[gc_count++] = rbconn;
}
if (gc_count) {
no_gc = true;
tree_nodes_free(
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