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354 lines
8.7 KiB
354 lines
8.7 KiB
/*
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* Network node table
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*
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* SELinux must keep a mapping of network nodes to labels/SIDs. This
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* mapping is maintained as part of the normal policy but a fast cache is
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* needed to reduce the lookup overhead since most of these queries happen on
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* a per-packet basis.
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*
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* Author: Paul Moore <paul.moore@hp.com>
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*
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* This code is heavily based on the "netif" concept originally developed by
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* James Morris <jmorris@redhat.com>
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* (see security/selinux/netif.c for more information)
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*
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*/
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/*
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* (c) Copyright Hewlett-Packard Development Company, L.P., 2007
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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 version 2 of the GNU General Public License as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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*/
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#include <linux/types.h>
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#include <linux/rcupdate.h>
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#include <linux/list.h>
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#include <linux/spinlock.h>
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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 <net/ip.h>
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#include <net/ipv6.h>
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#include <asm/bug.h>
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#include "objsec.h"
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#define SEL_NETNODE_HASH_SIZE 256
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#define SEL_NETNODE_HASH_BKT_LIMIT 16
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struct sel_netnode {
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struct netnode_security_struct nsec;
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struct list_head list;
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struct rcu_head rcu;
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};
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/* NOTE: we are using a combined hash table for both IPv4 and IPv6, the reason
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* for this is that I suspect most users will not make heavy use of both
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* address families at the same time so one table will usually end up wasted,
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* if this becomes a problem we can always add a hash table for each address
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* family later */
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static LIST_HEAD(sel_netnode_list);
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static DEFINE_SPINLOCK(sel_netnode_lock);
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static struct list_head sel_netnode_hash[SEL_NETNODE_HASH_SIZE];
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/**
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* sel_netnode_free - Frees a node entry
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* @p: the entry's RCU field
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*
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* Description:
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* This function is designed to be used as a callback to the call_rcu()
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* function so that memory allocated to a hash table node entry can be
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* released safely.
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*
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*/
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static void sel_netnode_free(struct rcu_head *p)
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{
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struct sel_netnode *node = container_of(p, struct sel_netnode, rcu);
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kfree(node);
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}
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/**
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* sel_netnode_hashfn_ipv4 - IPv4 hashing function for the node table
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* @addr: IPv4 address
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*
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* Description:
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* This is the IPv4 hashing function for the node interface table, it returns
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* the bucket number for the given IP address.
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*
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*/
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static u32 sel_netnode_hashfn_ipv4(__be32 addr)
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{
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/* at some point we should determine if the mismatch in byte order
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* affects the hash function dramatically */
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return (addr & (SEL_NETNODE_HASH_SIZE - 1));
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}
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/**
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* sel_netnode_hashfn_ipv6 - IPv6 hashing function for the node table
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* @addr: IPv6 address
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*
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* Description:
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* This is the IPv6 hashing function for the node interface table, it returns
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* the bucket number for the given IP address.
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*
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*/
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static u32 sel_netnode_hashfn_ipv6(const struct in6_addr *addr)
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{
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/* just hash the least significant 32 bits to keep things fast (they
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* are the most likely to be different anyway), we can revisit this
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* later if needed */
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return (addr->s6_addr32[3] & (SEL_NETNODE_HASH_SIZE - 1));
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}
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/**
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* sel_netnode_find - Search for a node record
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* @addr: IP address
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* @family: address family
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*
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* Description:
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* Search the network node table and return the record matching @addr. If an
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* entry can not be found in the table return NULL.
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*
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*/
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static struct sel_netnode *sel_netnode_find(const void *addr, u16 family)
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{
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u32 idx;
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struct sel_netnode *node;
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switch (family) {
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case PF_INET:
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idx = sel_netnode_hashfn_ipv4(*(__be32 *)addr);
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break;
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case PF_INET6:
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idx = sel_netnode_hashfn_ipv6(addr);
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break;
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default:
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BUG();
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}
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list_for_each_entry_rcu(node, &sel_netnode_hash[idx], list)
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if (node->nsec.family == family)
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switch (family) {
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case PF_INET:
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if (node->nsec.addr.ipv4 == *(__be32 *)addr)
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return node;
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break;
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case PF_INET6:
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if (ipv6_addr_equal(&node->nsec.addr.ipv6,
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addr))
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return node;
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break;
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}
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return NULL;
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}
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/**
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* sel_netnode_insert - Insert a new node into the table
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* @node: the new node record
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*
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* Description:
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* Add a new node record to the network address hash table. Returns zero on
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* success, negative values on failure.
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*
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*/
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static int sel_netnode_insert(struct sel_netnode *node)
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{
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u32 idx;
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u32 count = 0;
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struct sel_netnode *iter;
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switch (node->nsec.family) {
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case PF_INET:
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idx = sel_netnode_hashfn_ipv4(node->nsec.addr.ipv4);
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break;
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case PF_INET6:
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idx = sel_netnode_hashfn_ipv6(&node->nsec.addr.ipv6);
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break;
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default:
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BUG();
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}
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list_add_rcu(&node->list, &sel_netnode_hash[idx]);
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/* we need to impose a limit on the growth of the hash table so check
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* this bucket to make sure it is within the specified bounds */
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list_for_each_entry(iter, &sel_netnode_hash[idx], list)
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if (++count > SEL_NETNODE_HASH_BKT_LIMIT) {
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list_del_rcu(&iter->list);
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call_rcu(&iter->rcu, sel_netnode_free);
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break;
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}
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return 0;
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}
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/**
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* sel_netnode_destroy - Remove a node record from the table
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* @node: the existing node record
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*
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* Description:
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* Remove an existing node record from the network address table.
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*
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*/
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static void sel_netnode_destroy(struct sel_netnode *node)
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{
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list_del_rcu(&node->list);
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call_rcu(&node->rcu, sel_netnode_free);
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}
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/**
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* sel_netnode_sid_slow - Lookup the SID of a network address using the policy
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* @addr: the IP address
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* @family: the address family
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* @sid: node SID
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*
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* Description:
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* This function determines the SID of a network address by quering the
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* security policy. The result is added to the network address table to
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* speedup future queries. Returns zero on success, negative values on
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* failure.
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*
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*/
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static int sel_netnode_sid_slow(void *addr, u16 family, u32 *sid)
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{
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int ret;
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struct sel_netnode *node;
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struct sel_netnode *new = NULL;
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spin_lock_bh(&sel_netnode_lock);
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node = sel_netnode_find(addr, family);
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if (node != NULL) {
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*sid = node->nsec.sid;
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ret = 0;
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goto out;
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}
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new = kzalloc(sizeof(*new), GFP_ATOMIC);
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if (new == NULL) {
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ret = -ENOMEM;
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goto out;
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}
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switch (family) {
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case PF_INET:
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ret = security_node_sid(PF_INET,
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addr, sizeof(struct in_addr),
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&new->nsec.sid);
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new->nsec.addr.ipv4 = *(__be32 *)addr;
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break;
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case PF_INET6:
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ret = security_node_sid(PF_INET6,
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addr, sizeof(struct in6_addr),
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&new->nsec.sid);
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ipv6_addr_copy(&new->nsec.addr.ipv6, addr);
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break;
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default:
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BUG();
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}
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if (ret != 0)
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goto out;
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new->nsec.family = family;
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ret = sel_netnode_insert(new);
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if (ret != 0)
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goto out;
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*sid = new->nsec.sid;
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out:
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spin_unlock_bh(&sel_netnode_lock);
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if (unlikely(ret)) {
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printk(KERN_WARNING
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"SELinux: failure in sel_netnode_sid_slow(),"
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" unable to determine network node label\n");
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kfree(new);
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}
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return ret;
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}
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/**
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* sel_netnode_sid - Lookup the SID of a network address
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* @addr: the IP address
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* @family: the address family
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* @sid: node SID
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*
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* Description:
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* This function determines the SID of a network address using the fastest
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* method possible. First the address table is queried, but if an entry
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* can't be found then the policy is queried and the result is added to the
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* table to speedup future queries. Returns zero on success, negative values
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* on failure.
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*
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*/
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int sel_netnode_sid(void *addr, u16 family, u32 *sid)
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{
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struct sel_netnode *node;
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rcu_read_lock();
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node = sel_netnode_find(addr, family);
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if (node != NULL) {
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*sid = node->nsec.sid;
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rcu_read_unlock();
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return 0;
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}
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rcu_read_unlock();
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return sel_netnode_sid_slow(addr, family, sid);
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}
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/**
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* sel_netnode_flush - Flush the entire network address table
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*
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* Description:
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* Remove all entries from the network address table.
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*
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*/
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static void sel_netnode_flush(void)
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{
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u32 idx;
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struct sel_netnode *node;
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spin_lock_bh(&sel_netnode_lock);
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for (idx = 0; idx < SEL_NETNODE_HASH_SIZE; idx++)
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list_for_each_entry(node, &sel_netnode_hash[idx], list)
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sel_netnode_destroy(node);
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spin_unlock_bh(&sel_netnode_lock);
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}
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static int sel_netnode_avc_callback(u32 event, u32 ssid, u32 tsid,
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u16 class, u32 perms, u32 *retained)
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{
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if (event == AVC_CALLBACK_RESET) {
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sel_netnode_flush();
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synchronize_net();
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}
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return 0;
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}
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static __init int sel_netnode_init(void)
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{
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int iter;
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int ret;
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if (!selinux_enabled)
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return 0;
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for (iter = 0; iter < SEL_NETNODE_HASH_SIZE; iter++)
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INIT_LIST_HEAD(&sel_netnode_hash[iter]);
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ret = avc_add_callback(sel_netnode_avc_callback, AVC_CALLBACK_RESET,
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SECSID_NULL, SECSID_NULL, SECCLASS_NULL, 0);
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if (ret != 0)
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panic("avc_add_callback() failed, error %d\n", ret);
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return ret;
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}
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__initcall(sel_netnode_init);
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