--- /dev/null
+/* Expectation handling for nf_conntrack. */
+
+/* (C) 1999-2001 Paul `Rusty' Russell
+ * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
+ * (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/types.h>
+#include <linux/netfilter.h>
+#include <linux/skbuff.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <linux/stddef.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/percpu.h>
+#include <linux/kernel.h>
+
+#include <net/netfilter/nf_conntrack.h>
+#include <net/netfilter/nf_conntrack_core.h>
+#include <net/netfilter/nf_conntrack_expect.h>
+#include <net/netfilter/nf_conntrack_helper.h>
+#include <net/netfilter/nf_conntrack_tuple.h>
+
+LIST_HEAD(nf_conntrack_expect_list);
+EXPORT_SYMBOL_GPL(nf_conntrack_expect_list);
+
+struct kmem_cache *nf_conntrack_expect_cachep __read_mostly;
+static unsigned int nf_conntrack_expect_next_id;
+
+/* nf_conntrack_expect helper functions */
+void nf_ct_unlink_expect(struct nf_conntrack_expect *exp)
+{
+ struct nf_conn_help *master_help = nfct_help(exp->master);
+
+ NF_CT_ASSERT(master_help);
+ NF_CT_ASSERT(!timer_pending(&exp->timeout));
+
+ list_del(&exp->list);
+ NF_CT_STAT_INC(expect_delete);
+ master_help->expecting--;
+ nf_conntrack_expect_put(exp);
+}
+EXPORT_SYMBOL_GPL(nf_ct_unlink_expect);
+
+static void expectation_timed_out(unsigned long ul_expect)
+{
+ struct nf_conntrack_expect *exp = (void *)ul_expect;
+
+ write_lock_bh(&nf_conntrack_lock);
+ nf_ct_unlink_expect(exp);
+ write_unlock_bh(&nf_conntrack_lock);
+ nf_conntrack_expect_put(exp);
+}
+
+struct nf_conntrack_expect *
+__nf_conntrack_expect_find(const struct nf_conntrack_tuple *tuple)
+{
+ struct nf_conntrack_expect *i;
+
+ list_for_each_entry(i, &nf_conntrack_expect_list, list) {
+ if (nf_ct_tuple_mask_cmp(tuple, &i->tuple, &i->mask))
+ return i;
+ }
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(__nf_conntrack_expect_find);
+
+/* Just find a expectation corresponding to a tuple. */
+struct nf_conntrack_expect *
+nf_conntrack_expect_find_get(const struct nf_conntrack_tuple *tuple)
+{
+ struct nf_conntrack_expect *i;
+
+ read_lock_bh(&nf_conntrack_lock);
+ i = __nf_conntrack_expect_find(tuple);
+ if (i)
+ atomic_inc(&i->use);
+ read_unlock_bh(&nf_conntrack_lock);
+
+ return i;
+}
+EXPORT_SYMBOL_GPL(nf_conntrack_expect_find_get);
+
+/* If an expectation for this connection is found, it gets delete from
+ * global list then returned. */
+struct nf_conntrack_expect *
+find_expectation(const struct nf_conntrack_tuple *tuple)
+{
+ struct nf_conntrack_expect *exp;
+
+ exp = __nf_conntrack_expect_find(tuple);
+ if (!exp)
+ return NULL;
+
+ /* If master is not in hash table yet (ie. packet hasn't left
+ this machine yet), how can other end know about expected?
+ Hence these are not the droids you are looking for (if
+ master ct never got confirmed, we'd hold a reference to it
+ and weird things would happen to future packets). */
+ if (!nf_ct_is_confirmed(exp->master))
+ return NULL;
+
+ if (exp->flags & NF_CT_EXPECT_PERMANENT) {
+ atomic_inc(&exp->use);
+ return exp;
+ } else if (del_timer(&exp->timeout)) {
+ nf_ct_unlink_expect(exp);
+ return exp;
+ }
+
+ return NULL;
+}
+
+/* delete all expectations for this conntrack */
+void nf_ct_remove_expectations(struct nf_conn *ct)
+{
+ struct nf_conntrack_expect *i, *tmp;
+ struct nf_conn_help *help = nfct_help(ct);
+
+ /* Optimization: most connection never expect any others. */
+ if (!help || help->expecting == 0)
+ return;
+
+ list_for_each_entry_safe(i, tmp, &nf_conntrack_expect_list, list) {
+ if (i->master == ct && del_timer(&i->timeout)) {
+ nf_ct_unlink_expect(i);
+ nf_conntrack_expect_put(i);
+ }
+ }
+}
+EXPORT_SYMBOL_GPL(nf_ct_remove_expectations);
+
+/* Would two expected things clash? */
+static inline int expect_clash(const struct nf_conntrack_expect *a,
+ const struct nf_conntrack_expect *b)
+{
+ /* Part covered by intersection of masks must be unequal,
+ otherwise they clash */
+ struct nf_conntrack_tuple intersect_mask;
+ int count;
+
+ intersect_mask.src.l3num = a->mask.src.l3num & b->mask.src.l3num;
+ intersect_mask.src.u.all = a->mask.src.u.all & b->mask.src.u.all;
+ intersect_mask.dst.u.all = a->mask.dst.u.all & b->mask.dst.u.all;
+ intersect_mask.dst.protonum = a->mask.dst.protonum
+ & b->mask.dst.protonum;
+
+ for (count = 0; count < NF_CT_TUPLE_L3SIZE; count++){
+ intersect_mask.src.u3.all[count] =
+ a->mask.src.u3.all[count] & b->mask.src.u3.all[count];
+ }
+
+ for (count = 0; count < NF_CT_TUPLE_L3SIZE; count++){
+ intersect_mask.dst.u3.all[count] =
+ a->mask.dst.u3.all[count] & b->mask.dst.u3.all[count];
+ }
+
+ return nf_ct_tuple_mask_cmp(&a->tuple, &b->tuple, &intersect_mask);
+}
+
+static inline int expect_matches(const struct nf_conntrack_expect *a,
+ const struct nf_conntrack_expect *b)
+{
+ return a->master == b->master
+ && nf_ct_tuple_equal(&a->tuple, &b->tuple)
+ && nf_ct_tuple_equal(&a->mask, &b->mask);
+}
+
+/* Generally a bad idea to call this: could have matched already. */
+void nf_conntrack_unexpect_related(struct nf_conntrack_expect *exp)
+{
+ struct nf_conntrack_expect *i;
+
+ write_lock_bh(&nf_conntrack_lock);
+ /* choose the the oldest expectation to evict */
+ list_for_each_entry_reverse(i, &nf_conntrack_expect_list, list) {
+ if (expect_matches(i, exp) && del_timer(&i->timeout)) {
+ nf_ct_unlink_expect(i);
+ write_unlock_bh(&nf_conntrack_lock);
+ nf_conntrack_expect_put(i);
+ return;
+ }
+ }
+ write_unlock_bh(&nf_conntrack_lock);
+}
+EXPORT_SYMBOL_GPL(nf_conntrack_unexpect_related);
+
+/* We don't increase the master conntrack refcount for non-fulfilled
+ * conntracks. During the conntrack destruction, the expectations are
+ * always killed before the conntrack itself */
+struct nf_conntrack_expect *nf_conntrack_expect_alloc(struct nf_conn *me)
+{
+ struct nf_conntrack_expect *new;
+
+ new = kmem_cache_alloc(nf_conntrack_expect_cachep, GFP_ATOMIC);
+ if (!new)
+ return NULL;
+
+ new->master = me;
+ atomic_set(&new->use, 1);
+ return new;
+}
+EXPORT_SYMBOL_GPL(nf_conntrack_expect_alloc);
+
+void nf_conntrack_expect_init(struct nf_conntrack_expect *exp, int family,
+ union nf_conntrack_address *saddr,
+ union nf_conntrack_address *daddr,
+ u_int8_t proto, __be16 *src, __be16 *dst)
+{
+ int len;
+
+ if (family == AF_INET)
+ len = 4;
+ else
+ len = 16;
+
+ exp->flags = 0;
+ exp->expectfn = NULL;
+ exp->helper = NULL;
+ exp->tuple.src.l3num = family;
+ exp->tuple.dst.protonum = proto;
+ exp->mask.src.l3num = 0xFFFF;
+ exp->mask.dst.protonum = 0xFF;
+
+ if (saddr) {
+ memcpy(&exp->tuple.src.u3, saddr, len);
+ if (sizeof(exp->tuple.src.u3) > len)
+ /* address needs to be cleared for nf_ct_tuple_equal */
+ memset((void *)&exp->tuple.src.u3 + len, 0x00,
+ sizeof(exp->tuple.src.u3) - len);
+ memset(&exp->mask.src.u3, 0xFF, len);
+ if (sizeof(exp->mask.src.u3) > len)
+ memset((void *)&exp->mask.src.u3 + len, 0x00,
+ sizeof(exp->mask.src.u3) - len);
+ } else {
+ memset(&exp->tuple.src.u3, 0x00, sizeof(exp->tuple.src.u3));
+ memset(&exp->mask.src.u3, 0x00, sizeof(exp->mask.src.u3));
+ }
+
+ if (daddr) {
+ memcpy(&exp->tuple.dst.u3, daddr, len);
+ if (sizeof(exp->tuple.dst.u3) > len)
+ /* address needs to be cleared for nf_ct_tuple_equal */
+ memset((void *)&exp->tuple.dst.u3 + len, 0x00,
+ sizeof(exp->tuple.dst.u3) - len);
+ memset(&exp->mask.dst.u3, 0xFF, len);
+ if (sizeof(exp->mask.dst.u3) > len)
+ memset((void *)&exp->mask.dst.u3 + len, 0x00,
+ sizeof(exp->mask.dst.u3) - len);
+ } else {
+ memset(&exp->tuple.dst.u3, 0x00, sizeof(exp->tuple.dst.u3));
+ memset(&exp->mask.dst.u3, 0x00, sizeof(exp->mask.dst.u3));
+ }
+
+ if (src) {
+ exp->tuple.src.u.all = (__force u16)*src;
+ exp->mask.src.u.all = 0xFFFF;
+ } else {
+ exp->tuple.src.u.all = 0;
+ exp->mask.src.u.all = 0;
+ }
+
+ if (dst) {
+ exp->tuple.dst.u.all = (__force u16)*dst;
+ exp->mask.dst.u.all = 0xFFFF;
+ } else {
+ exp->tuple.dst.u.all = 0;
+ exp->mask.dst.u.all = 0;
+ }
+}
+EXPORT_SYMBOL_GPL(nf_conntrack_expect_init);
+
+void nf_conntrack_expect_put(struct nf_conntrack_expect *exp)
+{
+ if (atomic_dec_and_test(&exp->use))
+ kmem_cache_free(nf_conntrack_expect_cachep, exp);
+}
+EXPORT_SYMBOL_GPL(nf_conntrack_expect_put);
+
+static void nf_conntrack_expect_insert(struct nf_conntrack_expect *exp)
+{
+ struct nf_conn_help *master_help = nfct_help(exp->master);
+
+ atomic_inc(&exp->use);
+ master_help->expecting++;
+ list_add(&exp->list, &nf_conntrack_expect_list);
+
+ init_timer(&exp->timeout);
+ exp->timeout.data = (unsigned long)exp;
+ exp->timeout.function = expectation_timed_out;
+ exp->timeout.expires = jiffies + master_help->helper->timeout * HZ;
+ add_timer(&exp->timeout);
+
+ exp->id = ++nf_conntrack_expect_next_id;
+ atomic_inc(&exp->use);
+ NF_CT_STAT_INC(expect_create);
+}
+
+/* Race with expectations being used means we could have none to find; OK. */
+static void evict_oldest_expect(struct nf_conn *master)
+{
+ struct nf_conntrack_expect *i;
+
+ list_for_each_entry_reverse(i, &nf_conntrack_expect_list, list) {
+ if (i->master == master) {
+ if (del_timer(&i->timeout)) {
+ nf_ct_unlink_expect(i);
+ nf_conntrack_expect_put(i);
+ }
+ break;
+ }
+ }
+}
+
+static inline int refresh_timer(struct nf_conntrack_expect *i)
+{
+ struct nf_conn_help *master_help = nfct_help(i->master);
+
+ if (!del_timer(&i->timeout))
+ return 0;
+
+ i->timeout.expires = jiffies + master_help->helper->timeout*HZ;
+ add_timer(&i->timeout);
+ return 1;
+}
+
+int nf_conntrack_expect_related(struct nf_conntrack_expect *expect)
+{
+ struct nf_conntrack_expect *i;
+ struct nf_conn *master = expect->master;
+ struct nf_conn_help *master_help = nfct_help(master);
+ int ret;
+
+ NF_CT_ASSERT(master_help);
+
+ write_lock_bh(&nf_conntrack_lock);
+ list_for_each_entry(i, &nf_conntrack_expect_list, list) {
+ if (expect_matches(i, expect)) {
+ /* Refresh timer: if it's dying, ignore.. */
+ if (refresh_timer(i)) {
+ ret = 0;
+ goto out;
+ }
+ } else if (expect_clash(i, expect)) {
+ ret = -EBUSY;
+ goto out;
+ }
+ }
+ /* Will be over limit? */
+ if (master_help->helper->max_expected &&
+ master_help->expecting >= master_help->helper->max_expected)
+ evict_oldest_expect(master);
+
+ nf_conntrack_expect_insert(expect);
+ nf_conntrack_expect_event(IPEXP_NEW, expect);
+ ret = 0;
+out:
+ write_unlock_bh(&nf_conntrack_lock);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(nf_conntrack_expect_related);
+
+#ifdef CONFIG_PROC_FS
+static void *exp_seq_start(struct seq_file *s, loff_t *pos)
+{
+ struct list_head *e = &nf_conntrack_expect_list;
+ loff_t i;
+
+ /* strange seq_file api calls stop even if we fail,
+ * thus we need to grab lock since stop unlocks */
+ read_lock_bh(&nf_conntrack_lock);
+
+ if (list_empty(e))
+ return NULL;
+
+ for (i = 0; i <= *pos; i++) {
+ e = e->next;
+ if (e == &nf_conntrack_expect_list)
+ return NULL;
+ }
+ return e;
+}
+
+static void *exp_seq_next(struct seq_file *s, void *v, loff_t *pos)
+{
+ struct list_head *e = v;
+
+ ++*pos;
+ e = e->next;
+
+ if (e == &nf_conntrack_expect_list)
+ return NULL;
+
+ return e;
+}
+
+static void exp_seq_stop(struct seq_file *s, void *v)
+{
+ read_unlock_bh(&nf_conntrack_lock);
+}
+
+static int exp_seq_show(struct seq_file *s, void *v)
+{
+ struct nf_conntrack_expect *expect = v;
+
+ if (expect->timeout.function)
+ seq_printf(s, "%ld ", timer_pending(&expect->timeout)
+ ? (long)(expect->timeout.expires - jiffies)/HZ : 0);
+ else
+ seq_printf(s, "- ");
+ seq_printf(s, "l3proto = %u proto=%u ",
+ expect->tuple.src.l3num,
+ expect->tuple.dst.protonum);
+ print_tuple(s, &expect->tuple,
+ __nf_ct_l3proto_find(expect->tuple.src.l3num),
+ __nf_ct_l4proto_find(expect->tuple.src.l3num,
+ expect->tuple.dst.protonum));
+ return seq_putc(s, '\n');
+}
+
+static struct seq_operations exp_seq_ops = {
+ .start = exp_seq_start,
+ .next = exp_seq_next,
+ .stop = exp_seq_stop,
+ .show = exp_seq_show
+};
+
+static int exp_open(struct inode *inode, struct file *file)
+{
+ return seq_open(file, &exp_seq_ops);
+}
+
+struct file_operations exp_file_ops = {
+ .owner = THIS_MODULE,
+ .open = exp_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = seq_release
+};
+#endif /* CONFIG_PROC_FS */
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