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@@ -0,0 +1,365 @@
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+/* Expectation handling for nf_conntrack. */
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+
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+/* (C) 1999-2001 Paul `Rusty' Russell
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+ * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
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+ * (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org>
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+ *
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+ * This program is free software; you can redistribute it and/or modify
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+ * it under the terms of the GNU General Public License version 2 as
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+ * published by the Free Software Foundation.
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+ */
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+
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+#include <linux/types.h>
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+#include <linux/netfilter.h>
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+#include <linux/skbuff.h>
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+#include <linux/proc_fs.h>
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+#include <linux/seq_file.h>
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+#include <linux/stddef.h>
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+#include <linux/slab.h>
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+#include <linux/err.h>
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+#include <linux/percpu.h>
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+#include <linux/kernel.h>
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+
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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_expect.h>
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+#include <net/netfilter/nf_conntrack_helper.h>
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+#include <net/netfilter/nf_conntrack_tuple.h>
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+
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+LIST_HEAD(nf_conntrack_expect_list);
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+kmem_cache_t *nf_conntrack_expect_cachep __read_mostly;
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+DECLARE_PER_CPU(struct ip_conntrack_stat, nf_conntrack_stat);
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+static unsigned int nf_conntrack_expect_next_id;
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+
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+/* nf_conntrack_expect helper functions */
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+void nf_ct_unlink_expect(struct nf_conntrack_expect *exp)
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+{
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+ struct nf_conn_help *master_help = nfct_help(exp->master);
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+
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+ NF_CT_ASSERT(master_help);
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+ NF_CT_ASSERT(!timer_pending(&exp->timeout));
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+
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+ list_del(&exp->list);
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+ NF_CT_STAT_INC(expect_delete);
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+ master_help->expecting--;
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+ nf_conntrack_expect_put(exp);
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+}
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+
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+static void expectation_timed_out(unsigned long ul_expect)
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+{
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+ struct nf_conntrack_expect *exp = (void *)ul_expect;
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+
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+ write_lock_bh(&nf_conntrack_lock);
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+ nf_ct_unlink_expect(exp);
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+ write_unlock_bh(&nf_conntrack_lock);
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+ nf_conntrack_expect_put(exp);
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+}
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+
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+struct nf_conntrack_expect *
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+__nf_conntrack_expect_find(const struct nf_conntrack_tuple *tuple)
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+{
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+ struct nf_conntrack_expect *i;
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+
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+ list_for_each_entry(i, &nf_conntrack_expect_list, list) {
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+ if (nf_ct_tuple_mask_cmp(tuple, &i->tuple, &i->mask))
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+ return i;
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+ }
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+ return NULL;
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+}
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+
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+/* Just find a expectation corresponding to a tuple. */
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+struct nf_conntrack_expect *
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+nf_conntrack_expect_find(const struct nf_conntrack_tuple *tuple)
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+{
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+ struct nf_conntrack_expect *i;
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+
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+ read_lock_bh(&nf_conntrack_lock);
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+ i = __nf_conntrack_expect_find(tuple);
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+ if (i)
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+ atomic_inc(&i->use);
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+ read_unlock_bh(&nf_conntrack_lock);
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+
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+ return i;
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+}
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+
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+/* If an expectation for this connection is found, it gets delete from
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+ * global list then returned. */
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+struct nf_conntrack_expect *
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+find_expectation(const struct nf_conntrack_tuple *tuple)
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+{
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+ struct nf_conntrack_expect *i;
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+
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+ list_for_each_entry(i, &nf_conntrack_expect_list, list) {
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+ /* If master is not in hash table yet (ie. packet hasn't left
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+ this machine yet), how can other end know about expected?
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+ Hence these are not the droids you are looking for (if
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+ master ct never got confirmed, we'd hold a reference to it
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+ and weird things would happen to future packets). */
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+ if (nf_ct_tuple_mask_cmp(tuple, &i->tuple, &i->mask)
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+ && nf_ct_is_confirmed(i->master)) {
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+ if (i->flags & NF_CT_EXPECT_PERMANENT) {
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+ atomic_inc(&i->use);
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+ return i;
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+ } else if (del_timer(&i->timeout)) {
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+ nf_ct_unlink_expect(i);
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+ return i;
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+ }
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+ }
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+ }
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+ return NULL;
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+}
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+
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+/* delete all expectations for this conntrack */
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+void nf_ct_remove_expectations(struct nf_conn *ct)
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+{
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+ struct nf_conntrack_expect *i, *tmp;
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+ struct nf_conn_help *help = nfct_help(ct);
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+
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+ /* Optimization: most connection never expect any others. */
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+ if (!help || help->expecting == 0)
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+ return;
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+
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+ list_for_each_entry_safe(i, tmp, &nf_conntrack_expect_list, list) {
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+ if (i->master == ct && del_timer(&i->timeout)) {
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+ nf_ct_unlink_expect(i);
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+ nf_conntrack_expect_put(i);
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+ }
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+ }
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+}
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+
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+/* Would two expected things clash? */
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+static inline int expect_clash(const struct nf_conntrack_expect *a,
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+ const struct nf_conntrack_expect *b)
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+{
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+ /* Part covered by intersection of masks must be unequal,
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+ otherwise they clash */
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+ struct nf_conntrack_tuple intersect_mask;
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+ int count;
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+
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+ intersect_mask.src.l3num = a->mask.src.l3num & b->mask.src.l3num;
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+ intersect_mask.src.u.all = a->mask.src.u.all & b->mask.src.u.all;
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+ intersect_mask.dst.u.all = a->mask.dst.u.all & b->mask.dst.u.all;
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+ intersect_mask.dst.protonum = a->mask.dst.protonum
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+ & b->mask.dst.protonum;
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+
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+ for (count = 0; count < NF_CT_TUPLE_L3SIZE; count++){
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+ intersect_mask.src.u3.all[count] =
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+ a->mask.src.u3.all[count] & b->mask.src.u3.all[count];
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+ }
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+
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+ for (count = 0; count < NF_CT_TUPLE_L3SIZE; count++){
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+ intersect_mask.dst.u3.all[count] =
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+ a->mask.dst.u3.all[count] & b->mask.dst.u3.all[count];
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+ }
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+
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+ return nf_ct_tuple_mask_cmp(&a->tuple, &b->tuple, &intersect_mask);
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+}
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+
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+static inline int expect_matches(const struct nf_conntrack_expect *a,
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+ const struct nf_conntrack_expect *b)
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+{
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+ return a->master == b->master
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+ && nf_ct_tuple_equal(&a->tuple, &b->tuple)
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+ && nf_ct_tuple_equal(&a->mask, &b->mask);
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+}
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+
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+/* Generally a bad idea to call this: could have matched already. */
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+void nf_conntrack_unexpect_related(struct nf_conntrack_expect *exp)
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+{
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+ struct nf_conntrack_expect *i;
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+
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+ write_lock_bh(&nf_conntrack_lock);
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+ /* choose the the oldest expectation to evict */
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+ list_for_each_entry_reverse(i, &nf_conntrack_expect_list, list) {
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+ if (expect_matches(i, exp) && del_timer(&i->timeout)) {
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+ nf_ct_unlink_expect(i);
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+ write_unlock_bh(&nf_conntrack_lock);
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+ nf_conntrack_expect_put(i);
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+ return;
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+ }
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+ }
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+ write_unlock_bh(&nf_conntrack_lock);
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+}
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+
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+/* We don't increase the master conntrack refcount for non-fulfilled
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+ * conntracks. During the conntrack destruction, the expectations are
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+ * always killed before the conntrack itself */
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+struct nf_conntrack_expect *nf_conntrack_expect_alloc(struct nf_conn *me)
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+{
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+ struct nf_conntrack_expect *new;
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+
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+ new = kmem_cache_alloc(nf_conntrack_expect_cachep, GFP_ATOMIC);
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+ if (!new)
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+ return NULL;
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+
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+ new->master = me;
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+ atomic_set(&new->use, 1);
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+ return new;
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+}
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+
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+void nf_conntrack_expect_put(struct nf_conntrack_expect *exp)
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+{
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+ if (atomic_dec_and_test(&exp->use))
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+ kmem_cache_free(nf_conntrack_expect_cachep, exp);
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+}
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+
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+static void nf_conntrack_expect_insert(struct nf_conntrack_expect *exp)
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+{
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+ struct nf_conn_help *master_help = nfct_help(exp->master);
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+
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+ atomic_inc(&exp->use);
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+ master_help->expecting++;
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+ list_add(&exp->list, &nf_conntrack_expect_list);
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+
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+ init_timer(&exp->timeout);
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+ exp->timeout.data = (unsigned long)exp;
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+ exp->timeout.function = expectation_timed_out;
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+ exp->timeout.expires = jiffies + master_help->helper->timeout * HZ;
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+ add_timer(&exp->timeout);
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+
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+ exp->id = ++nf_conntrack_expect_next_id;
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+ atomic_inc(&exp->use);
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+ NF_CT_STAT_INC(expect_create);
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+}
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+
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+/* Race with expectations being used means we could have none to find; OK. */
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+static void evict_oldest_expect(struct nf_conn *master)
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+{
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+ struct nf_conntrack_expect *i;
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+
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+ list_for_each_entry_reverse(i, &nf_conntrack_expect_list, list) {
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+ if (i->master == master) {
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+ if (del_timer(&i->timeout)) {
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+ nf_ct_unlink_expect(i);
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+ nf_conntrack_expect_put(i);
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+ }
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+ break;
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+ }
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+ }
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+}
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+
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+static inline int refresh_timer(struct nf_conntrack_expect *i)
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+{
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+ struct nf_conn_help *master_help = nfct_help(i->master);
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+
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+ if (!del_timer(&i->timeout))
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+ return 0;
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+
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+ i->timeout.expires = jiffies + master_help->helper->timeout*HZ;
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+ add_timer(&i->timeout);
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+ return 1;
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+}
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+
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+int nf_conntrack_expect_related(struct nf_conntrack_expect *expect)
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+{
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+ struct nf_conntrack_expect *i;
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+ struct nf_conn *master = expect->master;
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+ struct nf_conn_help *master_help = nfct_help(master);
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+ int ret;
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+
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+ NF_CT_ASSERT(master_help);
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+
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+ write_lock_bh(&nf_conntrack_lock);
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+ list_for_each_entry(i, &nf_conntrack_expect_list, list) {
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+ if (expect_matches(i, expect)) {
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+ /* Refresh timer: if it's dying, ignore.. */
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+ if (refresh_timer(i)) {
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+ ret = 0;
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+ goto out;
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+ }
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+ } else if (expect_clash(i, expect)) {
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+ ret = -EBUSY;
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+ goto out;
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+ }
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+ }
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+ /* Will be over limit? */
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+ if (master_help->helper->max_expected &&
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+ master_help->expecting >= master_help->helper->max_expected)
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+ evict_oldest_expect(master);
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+
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+ nf_conntrack_expect_insert(expect);
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+ nf_conntrack_expect_event(IPEXP_NEW, expect);
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+ ret = 0;
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+out:
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+ write_unlock_bh(&nf_conntrack_lock);
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+ return ret;
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+}
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+
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+#ifdef CONFIG_PROC_FS
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+static void *exp_seq_start(struct seq_file *s, loff_t *pos)
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+{
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+ struct list_head *e = &nf_conntrack_expect_list;
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+ loff_t i;
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+
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+ /* strange seq_file api calls stop even if we fail,
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+ * thus we need to grab lock since stop unlocks */
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+ read_lock_bh(&nf_conntrack_lock);
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+
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+ if (list_empty(e))
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+ return NULL;
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+
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+ for (i = 0; i <= *pos; i++) {
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+ e = e->next;
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+ if (e == &nf_conntrack_expect_list)
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+ return NULL;
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+ }
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+ return e;
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+}
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+
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+static void *exp_seq_next(struct seq_file *s, void *v, loff_t *pos)
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+{
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+ struct list_head *e = v;
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+
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+ ++*pos;
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+ e = e->next;
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+
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+ if (e == &nf_conntrack_expect_list)
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+ return NULL;
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+
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+ return e;
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+}
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+
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+static void exp_seq_stop(struct seq_file *s, void *v)
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+{
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+ read_unlock_bh(&nf_conntrack_lock);
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+}
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+
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+static int exp_seq_show(struct seq_file *s, void *v)
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+{
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+ struct nf_conntrack_expect *expect = v;
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+
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+ if (expect->timeout.function)
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+ seq_printf(s, "%ld ", timer_pending(&expect->timeout)
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+ ? (long)(expect->timeout.expires - jiffies)/HZ : 0);
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+ else
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+ seq_printf(s, "- ");
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+ seq_printf(s, "l3proto = %u proto=%u ",
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+ expect->tuple.src.l3num,
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+ expect->tuple.dst.protonum);
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+ print_tuple(s, &expect->tuple,
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+ __nf_ct_l3proto_find(expect->tuple.src.l3num),
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+ __nf_ct_proto_find(expect->tuple.src.l3num,
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+ expect->tuple.dst.protonum));
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+ return seq_putc(s, '\n');
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+}
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+
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+static struct seq_operations exp_seq_ops = {
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+ .start = exp_seq_start,
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+ .next = exp_seq_next,
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+ .stop = exp_seq_stop,
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+ .show = exp_seq_show
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+};
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+
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+static int exp_open(struct inode *inode, struct file *file)
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+{
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+ return seq_open(file, &exp_seq_ops);
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+}
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+
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+struct file_operations exp_file_ops = {
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+ .owner = THIS_MODULE,
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+ .open = exp_open,
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+ .read = seq_read,
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+ .llseek = seq_lseek,
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+ .release = seq_release
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+};
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+#endif /* CONFIG_PROC_FS */
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Martin Josefsson