![Florian Westphal](/assets/img/avatar_default.png)
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 <fw@strlen.de> Acked-by: Yi-Hung Wei <yihung.wei@gmail.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
374 lines
9.1 KiB
C
374 lines
9.1 KiB
C
/*
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* count the number of connections matching an arbitrary key.
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*
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* (C) 2017 Red Hat GmbH
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* Author: Florian Westphal <fw@strlen.de>
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*
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* split from xt_connlimit.c:
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* (c) 2000 Gerd Knorr <kraxel@bytesex.org>
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* Nov 2002: Martin Bene <martin.bene@icomedias.com>:
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* only ignore TIME_WAIT or gone connections
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* (C) CC Computer Consultants GmbH, 2007
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/in.h>
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#include <linux/in6.h>
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#include <linux/ip.h>
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#include <linux/ipv6.h>
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#include <linux/jhash.h>
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#include <linux/slab.h>
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#include <linux/list.h>
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#include <linux/rbtree.h>
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#include <linux/module.h>
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#include <linux/random.h>
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#include <linux/skbuff.h>
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#include <linux/spinlock.h>
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#include <linux/netfilter/nf_conntrack_tcp.h>
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#include <linux/netfilter/x_tables.h>
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#include <net/netfilter/nf_conntrack.h>
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#include <net/netfilter/nf_conntrack_count.h>
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#include <net/netfilter/nf_conntrack_core.h>
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#include <net/netfilter/nf_conntrack_tuple.h>
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#include <net/netfilter/nf_conntrack_zones.h>
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#define CONNCOUNT_SLOTS 256U
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#ifdef CONFIG_LOCKDEP
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#define CONNCOUNT_LOCK_SLOTS 8U
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#else
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#define CONNCOUNT_LOCK_SLOTS 256U
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#endif
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#define CONNCOUNT_GC_MAX_NODES 8
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#define MAX_KEYLEN 5
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/* we will save the tuples of all connections we care about */
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struct nf_conncount_tuple {
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struct hlist_node node;
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struct nf_conntrack_tuple tuple;
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};
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struct nf_conncount_rb {
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struct rb_node node;
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struct hlist_head hhead; /* connections/hosts in same subnet */
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u32 key[MAX_KEYLEN];
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};
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static spinlock_t nf_conncount_locks[CONNCOUNT_LOCK_SLOTS] __cacheline_aligned_in_smp;
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struct nf_conncount_data {
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unsigned int keylen;
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struct rb_root root[CONNCOUNT_SLOTS];
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};
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static u_int32_t conncount_rnd __read_mostly;
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static struct kmem_cache *conncount_rb_cachep __read_mostly;
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static struct kmem_cache *conncount_conn_cachep __read_mostly;
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static inline bool already_closed(const struct nf_conn *conn)
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{
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if (nf_ct_protonum(conn) == IPPROTO_TCP)
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return conn->proto.tcp.state == TCP_CONNTRACK_TIME_WAIT ||
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conn->proto.tcp.state == TCP_CONNTRACK_CLOSE;
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else
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return 0;
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}
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static int key_diff(const u32 *a, const u32 *b, unsigned int klen)
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{
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return memcmp(a, b, klen * sizeof(u32));
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}
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static bool add_hlist(struct hlist_head *head,
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const struct nf_conntrack_tuple *tuple)
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{
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struct nf_conncount_tuple *conn;
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conn = kmem_cache_alloc(conncount_conn_cachep, GFP_ATOMIC);
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if (conn == NULL)
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return false;
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conn->tuple = *tuple;
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hlist_add_head(&conn->node, head);
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return true;
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}
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static unsigned int check_hlist(struct net *net,
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struct hlist_head *head,
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const struct nf_conntrack_tuple *tuple,
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const struct nf_conntrack_zone *zone,
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bool *addit)
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{
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const struct nf_conntrack_tuple_hash *found;
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struct nf_conncount_tuple *conn;
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struct hlist_node *n;
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struct nf_conn *found_ct;
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unsigned int length = 0;
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*addit = true;
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/* check the saved connections */
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hlist_for_each_entry_safe(conn, n, head, node) {
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found = nf_conntrack_find_get(net, zone, &conn->tuple);
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if (found == NULL) {
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hlist_del(&conn->node);
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kmem_cache_free(conncount_conn_cachep, conn);
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continue;
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}
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found_ct = nf_ct_tuplehash_to_ctrack(found);
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if (nf_ct_tuple_equal(&conn->tuple, tuple)) {
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/*
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* Just to be sure we have it only once in the list.
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* We should not see tuples twice unless someone hooks
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* this into a table without "-p tcp --syn".
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*/
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*addit = false;
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} else if (already_closed(found_ct)) {
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/*
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* we do not care about connections which are
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* closed already -> ditch it
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*/
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nf_ct_put(found_ct);
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hlist_del(&conn->node);
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kmem_cache_free(conncount_conn_cachep, conn);
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continue;
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}
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nf_ct_put(found_ct);
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length++;
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}
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return length;
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}
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static void tree_nodes_free(struct rb_root *root,
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struct nf_conncount_rb *gc_nodes[],
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unsigned int gc_count)
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{
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struct nf_conncount_rb *rbconn;
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while (gc_count) {
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rbconn = gc_nodes[--gc_count];
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rb_erase(&rbconn->node, root);
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kmem_cache_free(conncount_rb_cachep, rbconn);
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}
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}
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static unsigned int
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count_tree(struct net *net, struct rb_root *root,
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const u32 *key, u8 keylen,
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u8 family,
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const struct nf_conntrack_tuple *tuple,
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const struct nf_conntrack_zone *zone)
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{
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struct nf_conncount_rb *gc_nodes[CONNCOUNT_GC_MAX_NODES];
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struct rb_node **rbnode, *parent;
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struct nf_conncount_rb *rbconn;
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struct nf_conncount_tuple *conn;
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unsigned int gc_count;
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bool no_gc = false;
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restart:
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gc_count = 0;
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parent = NULL;
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rbnode = &(root->rb_node);
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while (*rbnode) {
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int diff;
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bool addit;
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rbconn = rb_entry(*rbnode, struct nf_conncount_rb, node);
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parent = *rbnode;
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diff = key_diff(key, rbconn->key, keylen);
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if (diff < 0) {
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rbnode = &((*rbnode)->rb_left);
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} else if (diff > 0) {
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rbnode = &((*rbnode)->rb_right);
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} else {
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/* same source network -> be counted! */
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unsigned int count;
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count = check_hlist(net, &rbconn->hhead, tuple, zone, &addit);
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tree_nodes_free(root, gc_nodes, gc_count);
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if (!addit)
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return count;
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if (!add_hlist(&rbconn->hhead, tuple))
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return 0; /* hotdrop */
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return count + 1;
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}
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if (no_gc || gc_count >= ARRAY_SIZE(gc_nodes))
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continue;
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/* only used for GC on hhead, retval and 'addit' ignored */
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check_hlist(net, &rbconn->hhead, tuple, zone, &addit);
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if (hlist_empty(&rbconn->hhead))
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gc_nodes[gc_count++] = rbconn;
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}
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if (gc_count) {
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no_gc = true;
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tree_nodes_free(root, gc_nodes, gc_count);
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/* tree_node_free before new allocation permits
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* allocator to re-use newly free'd object.
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*
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* This is a rare event; in most cases we will find
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* existing node to re-use. (or gc_count is 0).
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*/
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goto restart;
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}
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/* no match, need to insert new node */
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rbconn = kmem_cache_alloc(conncount_rb_cachep, GFP_ATOMIC);
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if (rbconn == NULL)
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return 0;
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conn = kmem_cache_alloc(conncount_conn_cachep, GFP_ATOMIC);
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if (conn == NULL) {
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kmem_cache_free(conncount_rb_cachep, rbconn);
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return 0;
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}
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conn->tuple = *tuple;
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memcpy(rbconn->key, key, sizeof(u32) * keylen);
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INIT_HLIST_HEAD(&rbconn->hhead);
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hlist_add_head(&conn->node, &rbconn->hhead);
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rb_link_node(&rbconn->node, parent, rbnode);
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rb_insert_color(&rbconn->node, root);
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return 1;
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}
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unsigned int nf_conncount_count(struct net *net,
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struct nf_conncount_data *data,
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const u32 *key,
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unsigned int family,
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const struct nf_conntrack_tuple *tuple,
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const struct nf_conntrack_zone *zone)
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{
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struct rb_root *root;
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int count;
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u32 hash;
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hash = jhash2(key, data->keylen, conncount_rnd) % CONNCOUNT_SLOTS;
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root = &data->root[hash];
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spin_lock_bh(&nf_conncount_locks[hash % CONNCOUNT_LOCK_SLOTS]);
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count = count_tree(net, root, key, data->keylen, family, tuple, zone);
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spin_unlock_bh(&nf_conncount_locks[hash % CONNCOUNT_LOCK_SLOTS]);
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return count;
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}
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EXPORT_SYMBOL_GPL(nf_conncount_count);
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struct nf_conncount_data *nf_conncount_init(struct net *net, unsigned int family,
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unsigned int keylen)
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{
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struct nf_conncount_data *data;
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int ret, i;
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if (keylen % sizeof(u32) ||
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keylen / sizeof(u32) > MAX_KEYLEN ||
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keylen == 0)
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return ERR_PTR(-EINVAL);
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net_get_random_once(&conncount_rnd, sizeof(conncount_rnd));
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data = kmalloc(sizeof(*data), GFP_KERNEL);
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if (!data)
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return ERR_PTR(-ENOMEM);
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ret = nf_ct_netns_get(net, family);
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if (ret < 0) {
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kfree(data);
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return ERR_PTR(ret);
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}
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for (i = 0; i < ARRAY_SIZE(data->root); ++i)
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data->root[i] = RB_ROOT;
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data->keylen = keylen / sizeof(u32);
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return data;
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}
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EXPORT_SYMBOL_GPL(nf_conncount_init);
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static void destroy_tree(struct rb_root *r)
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{
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struct nf_conncount_tuple *conn;
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struct nf_conncount_rb *rbconn;
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struct hlist_node *n;
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struct rb_node *node;
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while ((node = rb_first(r)) != NULL) {
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rbconn = rb_entry(node, struct nf_conncount_rb, node);
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rb_erase(node, r);
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hlist_for_each_entry_safe(conn, n, &rbconn->hhead, node)
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kmem_cache_free(conncount_conn_cachep, conn);
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kmem_cache_free(conncount_rb_cachep, rbconn);
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}
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}
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void nf_conncount_destroy(struct net *net, unsigned int family,
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struct nf_conncount_data *data)
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{
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unsigned int i;
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nf_ct_netns_put(net, family);
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for (i = 0; i < ARRAY_SIZE(data->root); ++i)
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destroy_tree(&data->root[i]);
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kfree(data);
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}
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EXPORT_SYMBOL_GPL(nf_conncount_destroy);
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static int __init nf_conncount_modinit(void)
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{
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int i;
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BUILD_BUG_ON(CONNCOUNT_LOCK_SLOTS > CONNCOUNT_SLOTS);
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BUILD_BUG_ON((CONNCOUNT_SLOTS % CONNCOUNT_LOCK_SLOTS) != 0);
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for (i = 0; i < CONNCOUNT_LOCK_SLOTS; ++i)
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spin_lock_init(&nf_conncount_locks[i]);
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conncount_conn_cachep = kmem_cache_create("nf_conncount_tuple",
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sizeof(struct nf_conncount_tuple),
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0, 0, NULL);
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if (!conncount_conn_cachep)
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return -ENOMEM;
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conncount_rb_cachep = kmem_cache_create("nf_conncount_rb",
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sizeof(struct nf_conncount_rb),
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0, 0, NULL);
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if (!conncount_rb_cachep) {
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kmem_cache_destroy(conncount_conn_cachep);
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return -ENOMEM;
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}
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return 0;
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}
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static void __exit nf_conncount_modexit(void)
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{
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kmem_cache_destroy(conncount_conn_cachep);
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kmem_cache_destroy(conncount_rb_cachep);
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}
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module_init(nf_conncount_modinit);
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module_exit(nf_conncount_modexit);
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MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
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MODULE_AUTHOR("Florian Westphal <fw@strlen.de>");
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MODULE_DESCRIPTION("netfilter: count number of connections matching a key");
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MODULE_LICENSE("GPL");
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