netlabel_addrlist.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * 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 <[email protected]>
 */

/*
 * (c) Copyright Hewlett-Packard Development Company, L.P., 2008
 */

#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 <linux/audit.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;
}

/**
 * netlbl_af4list_search_exact - Search for an exact IPv4 address entry
 * @addr: IPv4 address
 * @mask: IPv4 address mask
 * @head: the list head
 *
 * Description:
 * Searches the IPv4 address list given by @head.  If an exact match if 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_exact(__be32 addr,
						   __be32 mask,
						   struct list_head *head)
{
	struct netlbl_af4list *iter;

	list_for_each_entry_rcu(iter, head, list)
		if (iter->valid && iter->addr == addr && iter->mask == mask)
			return iter;

	return NULL;
}


#if IS_ENABLED(CONFIG_IPV6)
/**
 * 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;
}

/**
 * netlbl_af6list_search_exact - Search for an exact IPv6 address entry
 * @addr: IPv6 address
 * @mask: IPv6 address mask
 * @head: the list head
 *
 * Description:
 * Searches the IPv6 address list given by @head.  If an exact match if 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_exact(const struct in6_addr *addr,
						   const struct in6_addr *mask,
						   struct list_head *head)
{
	struct netlbl_af6list *iter;

	list_for_each_entry_rcu(iter, head, list)
		if (iter->valid &&
		    ipv6_addr_equal(&iter->addr, addr) &&
		    ipv6_addr_equal(&iter->mask, mask))
			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 IS_ENABLED(CONFIG_IPV6)
/**
 * 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_exact(addr, mask, head);
	if (entry == NULL)
		return NULL;
	netlbl_af4list_remove_entry(entry);
	return entry;
}

#if IS_ENABLED(CONFIG_IPV6)
/**
 * 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_exact(addr, mask, head);
	if (entry == NULL)
		return NULL;
	netlbl_af6list_remove_entry(entry);
	return entry;
}
#endif /* IPv6 */

/*
 * Audit Helper Functions
 */

#ifdef CONFIG_AUDIT
/**
 * netlbl_af4list_audit_addr - Audit an IPv4 address
 * @audit_buf: audit buffer
 * @src: true if source address, false if destination
 * @dev: network interface
 * @addr: IP address
 * @mask: IP address mask
 *
 * Description:
 * Write the IPv4 address and address mask, if necessary, to @audit_buf.
 *
 */
void netlbl_af4list_audit_addr(struct audit_buffer *audit_buf,
					int src, const char *dev,
					__be32 addr, __be32 mask)
{
	u32 mask_val = ntohl(mask);
	char *dir = (src ? "src" : "dst");

	if (dev != NULL)
		audit_log_format(audit_buf, " netif=%s", dev);
	audit_log_format(audit_buf, " %s=%pI4", dir, &addr);
	if (mask_val != 0xffffffff) {
		u32 mask_len = 0;
		while (mask_val > 0) {
			mask_val <<= 1;
			mask_len++;
		}
		audit_log_format(audit_buf, " %s_prefixlen=%d", dir, mask_len);
	}
}

#if IS_ENABLED(CONFIG_IPV6)
/**
 * netlbl_af6list_audit_addr - Audit an IPv6 address
 * @audit_buf: audit buffer
 * @src: true if source address, false if destination
 * @dev: network interface
 * @addr: IP address
 * @mask: IP address mask
 *
 * Description:
 * Write the IPv6 address and address mask, if necessary, to @audit_buf.
 *
 */
void netlbl_af6list_audit_addr(struct audit_buffer *audit_buf,
				 int src,
				 const char *dev,
				 const struct in6_addr *addr,
				 const struct in6_addr *mask)
{
	char *dir = (src ? "src" : "dst");

	if (dev != NULL)
		audit_log_format(audit_buf, " netif=%s", dev);
	audit_log_format(audit_buf, " %s=%pI6", dir, addr);
	if (ntohl(mask->s6_addr32[3]) != 0xffffffff) {
		u32 mask_len = 0;
		u32 mask_val;
		int iter = -1;
		while (ntohl(mask->s6_addr32[++iter]) == 0xffffffff)
			mask_len += 32;
		mask_val = ntohl(mask->s6_addr32[iter]);
		while (mask_val > 0) {
			mask_val <<= 1;
			mask_len++;
		}
		audit_log_format(audit_buf, " %s_prefixlen=%d", dir, mask_len);
	}
}
#endif /* IPv6 */
#endif /* CONFIG_AUDIT */