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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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![Sasha Levin](/assets/img/avatar_default.png)
I'm not sure why, but the hlist for each entry iterators were conceived list_for_each_entry(pos, head, member) The hlist ones were greedy and wanted an extra parameter: hlist_for_each_entry(tpos, pos, head, member) Why did they need an extra pos parameter? I'm not quite sure. Not only they don't really need it, it also prevents the iterator from looking exactly like the list iterator, which is unfortunate. Besides the semantic patch, there was some manual work required: - Fix up the actual hlist iterators in linux/list.h - Fix up the declaration of other iterators based on the hlist ones. - A very small amount of places were using the 'node' parameter, this was modified to use 'obj->member' instead. - Coccinelle didn't handle the hlist_for_each_entry_safe iterator properly, so those had to be fixed up manually. The semantic patch which is mostly the work of Peter Senna Tschudin is here: @@ iterator name hlist_for_each_entry, hlist_for_each_entry_continue, hlist_for_each_entry_from, hlist_for_each_entry_rcu, hlist_for_each_entry_rcu_bh, hlist_for_each_entry_continue_rcu_bh, for_each_busy_worker, ax25_uid_for_each, ax25_for_each, inet_bind_bucket_for_each, sctp_for_each_hentry, sk_for_each, sk_for_each_rcu, sk_for_each_from, sk_for_each_safe, sk_for_each_bound, hlist_for_each_entry_safe, hlist_for_each_entry_continue_rcu, nr_neigh_for_each, nr_neigh_for_each_safe, nr_node_for_each, nr_node_for_each_safe, for_each_gfn_indirect_valid_sp, for_each_gfn_sp, for_each_host; type T; expression a,c,d,e; identifier b; statement S; @@ -T b; <+... when != b ( hlist_for_each_entry(a, - b, c, d) S | hlist_for_each_entry_continue(a, - b, c) S | hlist_for_each_entry_from(a, - b, c) S | hlist_for_each_entry_rcu(a, - b, c, d) S | hlist_for_each_entry_rcu_bh(a, - b, c, d) S | hlist_for_each_entry_continue_rcu_bh(a, - b, c) S | for_each_busy_worker(a, c, - b, d) S | ax25_uid_for_each(a, - b, c) S | ax25_for_each(a, - b, c) S | inet_bind_bucket_for_each(a, - b, c) S | sctp_for_each_hentry(a, - b, c) S | sk_for_each(a, - b, c) S | sk_for_each_rcu(a, - b, c) S | sk_for_each_from -(a, b) +(a) S + sk_for_each_from(a) S | sk_for_each_safe(a, - b, c, d) S | sk_for_each_bound(a, - b, c) S | hlist_for_each_entry_safe(a, - b, c, d, e) S | hlist_for_each_entry_continue_rcu(a, - b, c) S | nr_neigh_for_each(a, - b, c) S | nr_neigh_for_each_safe(a, - b, c, d) S | nr_node_for_each(a, - b, c) S | nr_node_for_each_safe(a, - b, c, d) S | - for_each_gfn_sp(a, c, d, b) S + for_each_gfn_sp(a, c, d) S | - for_each_gfn_indirect_valid_sp(a, c, d, b) S + for_each_gfn_indirect_valid_sp(a, c, d) S | for_each_host(a, - b, c) S | for_each_host_safe(a, - b, c, d) S | for_each_mesh_entry(a, - b, c, d) S ) ...+> [akpm@linux-foundation.org: drop bogus change from net/ipv4/raw.c] [akpm@linux-foundation.org: drop bogus hunk from net/ipv6/raw.c] [akpm@linux-foundation.org: checkpatch fixes] [akpm@linux-foundation.org: fix warnings] [akpm@linux-foudnation.org: redo intrusive kvm changes] Tested-by: Peter Senna Tschudin <peter.senna@gmail.com> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Sasha Levin <sasha.levin@oracle.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Gleb Natapov <gleb@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
304 lines
7.7 KiB
C
304 lines
7.7 KiB
C
/*
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* netfilter module to limit the number of parallel tcp
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* connections per IP address.
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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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* based on ...
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*
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* Kernel module to match connection tracking information.
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* GPL (C) 1999 Rusty Russell (rusty@rustcorp.com.au).
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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/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 <linux/netfilter/xt_connlimit.h>
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#include <net/netfilter/nf_conntrack.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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/* we will save the tuples of all connections we care about */
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struct xt_connlimit_conn {
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struct hlist_node node;
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struct nf_conntrack_tuple tuple;
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union nf_inet_addr addr;
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};
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struct xt_connlimit_data {
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struct hlist_head iphash[256];
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spinlock_t lock;
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};
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static u_int32_t connlimit_rnd __read_mostly;
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static inline unsigned int connlimit_iphash(__be32 addr)
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{
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return jhash_1word((__force __u32)addr, connlimit_rnd) & 0xFF;
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}
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static inline unsigned int
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connlimit_iphash6(const union nf_inet_addr *addr,
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const union nf_inet_addr *mask)
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{
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union nf_inet_addr res;
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unsigned int i;
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for (i = 0; i < ARRAY_SIZE(addr->ip6); ++i)
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res.ip6[i] = addr->ip6[i] & mask->ip6[i];
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return jhash2((u32 *)res.ip6, ARRAY_SIZE(res.ip6), connlimit_rnd) & 0xFF;
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}
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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 inline unsigned int
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same_source_net(const union nf_inet_addr *addr,
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const union nf_inet_addr *mask,
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const union nf_inet_addr *u3, u_int8_t family)
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{
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if (family == NFPROTO_IPV4) {
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return (addr->ip & mask->ip) == (u3->ip & mask->ip);
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} else {
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union nf_inet_addr lh, rh;
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unsigned int i;
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for (i = 0; i < ARRAY_SIZE(addr->ip6); ++i) {
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lh.ip6[i] = addr->ip6[i] & mask->ip6[i];
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rh.ip6[i] = u3->ip6[i] & mask->ip6[i];
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}
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return memcmp(&lh.ip6, &rh.ip6, sizeof(lh.ip6)) == 0;
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}
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}
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static int count_them(struct net *net,
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struct xt_connlimit_data *data,
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const struct nf_conntrack_tuple *tuple,
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const union nf_inet_addr *addr,
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const union nf_inet_addr *mask,
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u_int8_t family)
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{
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const struct nf_conntrack_tuple_hash *found;
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struct xt_connlimit_conn *conn;
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struct hlist_node *n;
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struct nf_conn *found_ct;
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struct hlist_head *hash;
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bool addit = true;
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int matches = 0;
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if (family == NFPROTO_IPV6)
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hash = &data->iphash[connlimit_iphash6(addr, mask)];
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else
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hash = &data->iphash[connlimit_iphash(addr->ip & mask->ip)];
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rcu_read_lock();
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/* check the saved connections */
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hlist_for_each_entry_safe(conn, n, hash, node) {
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found = nf_conntrack_find_get(net, NF_CT_DEFAULT_ZONE,
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&conn->tuple);
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found_ct = NULL;
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if (found != NULL)
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found_ct = nf_ct_tuplehash_to_ctrack(found);
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if (found_ct != NULL &&
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nf_ct_tuple_equal(&conn->tuple, tuple) &&
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!already_closed(found_ct))
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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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if (found == NULL) {
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/* this one is gone */
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hlist_del(&conn->node);
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kfree(conn);
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continue;
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}
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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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kfree(conn);
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continue;
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}
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if (same_source_net(addr, mask, &conn->addr, family))
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/* same source network -> be counted! */
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++matches;
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nf_ct_put(found_ct);
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}
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rcu_read_unlock();
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if (addit) {
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/* save the new connection in our list */
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conn = kmalloc(sizeof(*conn), GFP_ATOMIC);
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if (conn == NULL)
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return -ENOMEM;
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conn->tuple = *tuple;
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conn->addr = *addr;
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hlist_add_head(&conn->node, hash);
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++matches;
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}
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return matches;
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}
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static bool
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connlimit_mt(const struct sk_buff *skb, struct xt_action_param *par)
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{
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struct net *net = dev_net(par->in ? par->in : par->out);
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const struct xt_connlimit_info *info = par->matchinfo;
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union nf_inet_addr addr;
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struct nf_conntrack_tuple tuple;
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const struct nf_conntrack_tuple *tuple_ptr = &tuple;
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enum ip_conntrack_info ctinfo;
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const struct nf_conn *ct;
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int connections;
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ct = nf_ct_get(skb, &ctinfo);
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if (ct != NULL)
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tuple_ptr = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
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else if (!nf_ct_get_tuplepr(skb, skb_network_offset(skb),
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par->family, &tuple))
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goto hotdrop;
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if (par->family == NFPROTO_IPV6) {
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const struct ipv6hdr *iph = ipv6_hdr(skb);
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memcpy(&addr.ip6, (info->flags & XT_CONNLIMIT_DADDR) ?
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&iph->daddr : &iph->saddr, sizeof(addr.ip6));
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} else {
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const struct iphdr *iph = ip_hdr(skb);
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addr.ip = (info->flags & XT_CONNLIMIT_DADDR) ?
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iph->daddr : iph->saddr;
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}
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spin_lock_bh(&info->data->lock);
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connections = count_them(net, info->data, tuple_ptr, &addr,
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&info->mask, par->family);
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spin_unlock_bh(&info->data->lock);
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if (connections < 0)
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/* kmalloc failed, drop it entirely */
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goto hotdrop;
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return (connections > info->limit) ^
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!!(info->flags & XT_CONNLIMIT_INVERT);
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hotdrop:
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par->hotdrop = true;
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return false;
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}
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static int connlimit_mt_check(const struct xt_mtchk_param *par)
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{
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struct xt_connlimit_info *info = par->matchinfo;
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unsigned int i;
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int ret;
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if (unlikely(!connlimit_rnd)) {
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u_int32_t rand;
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do {
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get_random_bytes(&rand, sizeof(rand));
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} while (!rand);
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cmpxchg(&connlimit_rnd, 0, rand);
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}
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ret = nf_ct_l3proto_try_module_get(par->family);
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if (ret < 0) {
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pr_info("cannot load conntrack support for "
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"address family %u\n", par->family);
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return ret;
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}
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/* init private data */
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info->data = kmalloc(sizeof(struct xt_connlimit_data), GFP_KERNEL);
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if (info->data == NULL) {
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nf_ct_l3proto_module_put(par->family);
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return -ENOMEM;
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}
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spin_lock_init(&info->data->lock);
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for (i = 0; i < ARRAY_SIZE(info->data->iphash); ++i)
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INIT_HLIST_HEAD(&info->data->iphash[i]);
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return 0;
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}
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static void connlimit_mt_destroy(const struct xt_mtdtor_param *par)
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{
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const struct xt_connlimit_info *info = par->matchinfo;
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struct xt_connlimit_conn *conn;
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struct hlist_node *n;
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struct hlist_head *hash = info->data->iphash;
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unsigned int i;
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nf_ct_l3proto_module_put(par->family);
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for (i = 0; i < ARRAY_SIZE(info->data->iphash); ++i) {
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hlist_for_each_entry_safe(conn, n, &hash[i], node) {
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hlist_del(&conn->node);
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kfree(conn);
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}
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}
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kfree(info->data);
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}
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static struct xt_match connlimit_mt_reg __read_mostly = {
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.name = "connlimit",
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.revision = 1,
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.family = NFPROTO_UNSPEC,
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.checkentry = connlimit_mt_check,
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.match = connlimit_mt,
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.matchsize = sizeof(struct xt_connlimit_info),
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.destroy = connlimit_mt_destroy,
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.me = THIS_MODULE,
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};
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static int __init connlimit_mt_init(void)
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{
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return xt_register_match(&connlimit_mt_reg);
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}
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static void __exit connlimit_mt_exit(void)
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{
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xt_unregister_match(&connlimit_mt_reg);
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}
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module_init(connlimit_mt_init);
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module_exit(connlimit_mt_exit);
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MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
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MODULE_DESCRIPTION("Xtables: Number of connections matching");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("ipt_connlimit");
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MODULE_ALIAS("ip6t_connlimit");
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