From 625c556118f3c2fd28bb8ef6da18c53bd4037be4 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Sat, 9 Dec 2017 21:01:08 +0100 Subject: netfilter: connlimit: split xt_connlimit into front and backend This allows to reuse xt_connlimit infrastructure from nf_tables. The upcoming nf_tables frontend can just pass in an nftables register as input key, this allows limiting by any nft-supported key, including concatenations. For xt_connlimit, pass in the zone and the ip/ipv6 address. With help from Yi-Hung Wei. Signed-off-by: Florian Westphal Acked-by: Yi-Hung Wei Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_conncount.c | 373 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 373 insertions(+) create mode 100644 net/netfilter/nf_conncount.c (limited to 'net/netfilter/nf_conncount.c') diff --git a/net/netfilter/nf_conncount.c b/net/netfilter/nf_conncount.c new file mode 100644 index 000000000000..a95518261168 --- /dev/null +++ b/net/netfilter/nf_conncount.c @@ -0,0 +1,373 @@ +/* + * count the number of connections matching an arbitrary key. + * + * (C) 2017 Red Hat GmbH + * Author: Florian Westphal + * + * split from xt_connlimit.c: + * (c) 2000 Gerd Knorr + * Nov 2002: Martin Bene : + * only ignore TIME_WAIT or gone connections + * (C) CC Computer Consultants GmbH, 2007 + */ +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#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_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 0; +} + +static int key_diff(const u32 *a, const u32 *b, unsigned int klen) +{ + return memcmp(a, b, klen * sizeof(u32)); +} + +static bool add_hlist(struct hlist_head *head, + const struct nf_conntrack_tuple *tuple) +{ + struct nf_conncount_tuple *conn; + + conn = kmem_cache_alloc(conncount_conn_cachep, GFP_ATOMIC); + if (conn == NULL) + return false; + conn->tuple = *tuple; + hlist_add_head(&conn->node, head); + return true; +} + +static unsigned int check_hlist(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 hlist_node *n; + struct nf_conn *found_ct; + unsigned int length = 0; + + *addit = true; + + /* check the saved connections */ + hlist_for_each_entry_safe(conn, n, head, node) { + found = nf_conntrack_find_get(net, zone, &conn->tuple); + if (found == NULL) { + hlist_del(&conn->node); + kmem_cache_free(conncount_conn_cachep, conn); + continue; + } + + found_ct = nf_ct_tuplehash_to_ctrack(found); + + if (nf_ct_tuple_equal(&conn->tuple, tuple)) { + /* + * 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; +} + +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, + u8 family, + 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 = check_hlist(net, &rbconn->hhead, tuple, zone, &addit); + + tree_nodes_free(root, gc_nodes, gc_count); + if (!addit) + return count; + + if (!add_hlist(&rbconn->hhead, tuple)) + 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 */ + check_hlist(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(root, gc_nodes, gc_count); + /* tree_node_free before new allocation permits + * allocator to re-use newly free'd object. + * + * This is a rare event; in most cases we will find + * existing node to re-use. (or gc_count is 0). + */ + goto restart; + } + + /* no match, need to insert new node */ + rbconn = kmem_cache_alloc(conncount_rb_cachep, GFP_ATOMIC); + if (rbconn == NULL) + return 0; + + conn = kmem_cache_alloc(conncount_conn_cachep, GFP_ATOMIC); + if (conn == NULL) { + kmem_cache_free(conncount_rb_cachep, rbconn); + return 0; + } + + conn->tuple = *tuple; + memcpy(rbconn->key, key, sizeof(u32) * keylen); + + INIT_HLIST_HEAD(&rbconn->hhead); + hlist_add_head(&conn->node, &rbconn->hhead); + + rb_link_node(&rbconn->node, parent, rbnode); + rb_insert_color(&rbconn->node, root); + return 1; +} + +unsigned int nf_conncount_count(struct net *net, + struct nf_conncount_data *data, + const u32 *key, + unsigned int family, + const struct nf_conntrack_tuple *tuple, + const struct nf_conntrack_zone *zone) +{ + struct rb_root *root; + int count; + u32 hash; + + hash = jhash2(key, data->keylen, conncount_rnd) % CONNCOUNT_SLOTS; + root = &data->root[hash]; + + spin_lock_bh(&nf_conncount_locks[hash % CONNCOUNT_LOCK_SLOTS]); + + count = count_tree(net, root, key, data->keylen, family, tuple, zone); + + spin_unlock_bh(&nf_conncount_locks[hash % CONNCOUNT_LOCK_SLOTS]); + + return count; +} +EXPORT_SYMBOL_GPL(nf_conncount_count); + +struct nf_conncount_data *nf_conncount_init(struct net *net, unsigned int family, + unsigned int keylen) +{ + struct nf_conncount_data *data; + int ret, i; + + if (keylen % sizeof(u32) || + keylen / sizeof(u32) > MAX_KEYLEN || + keylen == 0) + return ERR_PTR(-EINVAL); + + net_get_random_once(&conncount_rnd, sizeof(conncount_rnd)); + + data = kmalloc(sizeof(*data), GFP_KERNEL); + if (!data) + return ERR_PTR(-ENOMEM); + + ret = nf_ct_netns_get(net, family); + if (ret < 0) { + kfree(data); + return ERR_PTR(ret); + } + + for (i = 0; i < ARRAY_SIZE(data->root); ++i) + data->root[i] = RB_ROOT; + + data->keylen = keylen / sizeof(u32); + + return data; +} +EXPORT_SYMBOL_GPL(nf_conncount_init); + +static void destroy_tree(struct rb_root *r) +{ + struct nf_conncount_tuple *conn; + struct nf_conncount_rb *rbconn; + struct hlist_node *n; + struct rb_node *node; + + while ((node = rb_first(r)) != NULL) { + rbconn = rb_entry(node, struct nf_conncount_rb, node); + + rb_erase(node, r); + + hlist_for_each_entry_safe(conn, n, &rbconn->hhead, node) + kmem_cache_free(conncount_conn_cachep, conn); + + kmem_cache_free(conncount_rb_cachep, rbconn); + } +} + +void nf_conncount_destroy(struct net *net, unsigned int family, + struct nf_conncount_data *data) +{ + unsigned int i; + + nf_ct_netns_put(net, family); + + for (i = 0; i < ARRAY_SIZE(data->root); ++i) + destroy_tree(&data->root[i]); + + kfree(data); +} +EXPORT_SYMBOL_GPL(nf_conncount_destroy); + +static int __init nf_conncount_modinit(void) +{ + int i; + + BUILD_BUG_ON(CONNCOUNT_LOCK_SLOTS > CONNCOUNT_SLOTS); + BUILD_BUG_ON((CONNCOUNT_SLOTS % CONNCOUNT_LOCK_SLOTS) != 0); + + for (i = 0; i < CONNCOUNT_LOCK_SLOTS; ++i) + spin_lock_init(&nf_conncount_locks[i]); + + conncount_conn_cachep = kmem_cache_create("nf_conncount_tuple", + sizeof(struct nf_conncount_tuple), + 0, 0, NULL); + if (!conncount_conn_cachep) + return -ENOMEM; + + conncount_rb_cachep = kmem_cache_create("nf_conncount_rb", + sizeof(struct nf_conncount_rb), + 0, 0, NULL); + if (!conncount_rb_cachep) { + kmem_cache_destroy(conncount_conn_cachep); + return -ENOMEM; + } + + return 0; +} + +static void __exit nf_conncount_modexit(void) +{ + kmem_cache_destroy(conncount_conn_cachep); + kmem_cache_destroy(conncount_rb_cachep); +} + +module_init(nf_conncount_modinit); +module_exit(nf_conncount_modexit); +MODULE_AUTHOR("Jan Engelhardt "); +MODULE_AUTHOR("Florian Westphal "); +MODULE_DESCRIPTION("netfilter: count number of connections matching a key"); +MODULE_LICENSE("GPL"); -- cgit v1.2.3