netlabel: Add a generic way to create ordered linked lists of network addrs

Create an ordered IP address linked list mechanism similar to the core
kernel's linked list construct.  The idea behind this list functionality
is to create an extensibile linked list ordered by IP address mask to
ease the matching of network addresses.  The linked list is ordered with
larger address masks at the front of the list and shorter address masks
at the end to facilitate overriding network entries with individual host
or subnet entries.

Signed-off-by: Paul Moore <paul.moore@hp.com>
Reviewed-by: James Morris <jmorris@namei.org>

1 files changed, 258 insertions, 0 deletions

diff --git a/net/netlabel/netlabel_addrlist.c b/net/netlabel/netlabel_addrlist.c
new file mode 100644
index 0000000..dd928aa
--- /dev/null
+++ b/net/netlabel/netlabel_addrlist.c
@@ -0,0 +1,258 @@
+/*
+ * NetLabel Network Address Lists
+ *
+ * This file contains network address list functions used to manage ordered
+ * lists of network addresses for use by the NetLabel subsystem.  The NetLabel
+ * system manages static and dynamic label mappings for network protocols such
+ * as CIPSO and RIPSO.
+ *
+ * Author: Paul Moore <paul.moore@hp.com>
+ *
+ */
+
+/*
+ * (c) Copyright Hewlett-Packard Development Company, L.P., 2008
+ *
+ * This program is free software;  you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY;  without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
+ * the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program;  if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ */
+
+#include <linux/types.h>
+#include <linux/rcupdate.h>
+#include <linux/list.h>
+#include <linux/spinlock.h>
+#include <linux/in.h>
+#include <linux/in6.h>
+#include <linux/ip.h>
+#include <linux/ipv6.h>
+#include <net/ip.h>
+#include <net/ipv6.h>
+
+#include "netlabel_addrlist.h"
+
+/*
+ * Address List Functions
+ */
+
+/**
+ * netlbl_af4list_search - Search for a matching IPv4 address entry
+ * @addr: IPv4 address
+ * @head: the list head
+ *
+ * Description:
+ * Searches the IPv4 address list given by @head.  If a matching address entry
+ * is found it is returned, otherwise NULL is returned.  The caller is
+ * responsible for calling the rcu_read_[un]lock() functions.
+ *
+ */
+struct netlbl_af4list *netlbl_af4list_search(__be32 addr,
+					     struct list_head *head)
+{
+	struct netlbl_af4list *iter;
+
+	list_for_each_entry_rcu(iter, head, list)
+		if (iter->valid && (addr & iter->mask) == iter->addr)
+			return iter;
+
+	return NULL;
+}
+
+#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
+/**
+ * netlbl_af6list_search - Search for a matching IPv6 address entry
+ * @addr: IPv6 address
+ * @head: the list head
+ *
+ * Description:
+ * Searches the IPv6 address list given by @head.  If a matching address entry
+ * is found it is returned, otherwise NULL is returned.  The caller is
+ * responsible for calling the rcu_read_[un]lock() functions.
+ *
+ */
+struct netlbl_af6list *netlbl_af6list_search(const struct in6_addr *addr,
+					     struct list_head *head)
+{
+	struct netlbl_af6list *iter;
+
+	list_for_each_entry_rcu(iter, head, list)
+		if (iter->valid &&
+		    ipv6_masked_addr_cmp(&iter->addr, &iter->mask, addr) == 0)
+			return iter;
+
+	return NULL;
+}
+#endif /* IPv6 */
+
+/**
+ * netlbl_af4list_add - Add a new IPv4 address entry to a list
+ * @entry: address entry
+ * @head: the list head
+ *
+ * Description:
+ * Add a new address entry to the list pointed to by @head.  On success zero is
+ * returned, otherwise a negative value is returned.  The caller is responsible
+ * for calling the necessary locking functions.
+ *
+ */
+int netlbl_af4list_add(struct netlbl_af4list *entry, struct list_head *head)
+{
+	struct netlbl_af4list *iter;
+
+	iter = netlbl_af4list_search(entry->addr, head);
+	if (iter != NULL &&
+	    iter->addr == entry->addr && iter->mask == entry->mask)
+		return -EEXIST;
+
+	/* in order to speed up address searches through the list (the common
+	 * case) we need to keep the list in order based on the size of the
+	 * address mask such that the entry with the widest mask (smallest
+	 * numerical value) appears first in the list */
+	list_for_each_entry_rcu(iter, head, list)
+		if (iter->valid &&
+		    ntohl(entry->mask) > ntohl(iter->mask)) {
+			__list_add_rcu(&entry->list,
+				       iter->list.prev,
+				       &iter->list);
+			return 0;
+		}
+	list_add_tail_rcu(&entry->list, head);
+	return 0;
+}
+
+#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
+/**
+ * netlbl_af6list_add - Add a new IPv6 address entry to a list
+ * @entry: address entry
+ * @head: the list head
+ *
+ * Description:
+ * Add a new address entry to the list pointed to by @head.  On success zero is
+ * returned, otherwise a negative value is returned.  The caller is responsible
+ * for calling the necessary locking functions.
+ *
+ */
+int netlbl_af6list_add(struct netlbl_af6list *entry, struct list_head *head)
+{
+	struct netlbl_af6list *iter;
+
+	iter = netlbl_af6list_search(&entry->addr, head);
+	if (iter != NULL &&
+	    ipv6_addr_equal(&iter->addr, &entry->addr) &&
+	    ipv6_addr_equal(&iter->mask, &entry->mask))
+		return -EEXIST;
+
+	/* in order to speed up address searches through the list (the common
+	 * case) we need to keep the list in order based on the size of the
+	 * address mask such that the entry with the widest mask (smallest
+	 * numerical value) appears first in the list */
+	list_for_each_entry_rcu(iter, head, list)
+		if (iter->valid &&
+		    ipv6_addr_cmp(&entry->mask, &iter->mask) > 0) {
+			__list_add_rcu(&entry->list,
+				       iter->list.prev,
+				       &iter->list);
+			return 0;
+		}
+	list_add_tail_rcu(&entry->list, head);
+	return 0;
+}
+#endif /* IPv6 */
+
+/**
+ * netlbl_af4list_remove_entry - Remove an IPv4 address entry
+ * @entry: address entry
+ *
+ * Description:
+ * Remove the specified IP address entry.  The caller is responsible for
+ * calling the necessary locking functions.
+ *
+ */
+void netlbl_af4list_remove_entry(struct netlbl_af4list *entry)
+{
+	entry->valid = 0;
+	list_del_rcu(&entry->list);
+}
+
+/**
+ * netlbl_af4list_remove - Remove an IPv4 address entry
+ * @addr: IP address
+ * @mask: IP address mask
+ * @head: the list head
+ *
+ * Description:
+ * Remove an IP address entry from the list pointed to by @head.  Returns the
+ * entry on success, NULL on failure.  The caller is responsible for calling
+ * the necessary locking functions.
+ *
+ */
+struct netlbl_af4list *netlbl_af4list_remove(__be32 addr, __be32 mask,
+					     struct list_head *head)
+{
+	struct netlbl_af4list *entry;
+
+	entry = netlbl_af4list_search(addr, head);
+	if (entry != NULL && entry->addr == addr && entry->mask == mask) {
+		netlbl_af4list_remove_entry(entry);
+		return entry;
+	}
+
+	return NULL;
+}
+
+#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
+/**
+ * netlbl_af6list_remove_entry - Remove an IPv6 address entry
+ * @entry: address entry
+ *
+ * Description:
+ * Remove the specified IP address entry.  The caller is responsible for
+ * calling the necessary locking functions.
+ *
+ */
+void netlbl_af6list_remove_entry(struct netlbl_af6list *entry)
+{
+	entry->valid = 0;
+	list_del_rcu(&entry->list);
+}
+
+/**
+ * netlbl_af6list_remove - Remove an IPv6 address entry
+ * @addr: IP address
+ * @mask: IP address mask
+ * @head: the list head
+ *
+ * Description:
+ * Remove an IP address entry from the list pointed to by @head.  Returns the
+ * entry on success, NULL on failure.  The caller is responsible for calling
+ * the necessary locking functions.
+ *
+ */
+struct netlbl_af6list *netlbl_af6list_remove(const struct in6_addr *addr,
+					     const struct in6_addr *mask,
+					     struct list_head *head)
+{
+	struct netlbl_af6list *entry;
+
+	entry = netlbl_af6list_search(addr, head);
+	if (entry != NULL &&
+	    ipv6_addr_equal(&entry->addr, addr) &&
+	    ipv6_addr_equal(&entry->mask, mask)) {
+		netlbl_af6list_remove_entry(entry);
+		return entry;
+	}
+
+	return NULL;
+}
+#endif /* IPv6 */