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![Paul E. McKenney](/assets/img/avatar_default.png)
The attached patch needs to move from -rt to mainline given preemptable RCU. This patch fixes SELinux code that implicitly assumes that disabling preemption prevents an RCU grace period from completing, an assumption that is valid for Classic RCU, but not necessarily for preemptable RCU. Explicit rcu_read_lock() calls are thus added. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: James Morris <jmorris@namei.org>
319 lines
7.6 KiB
C
319 lines
7.6 KiB
C
/*
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* Network interface table.
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*
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* Network interfaces (devices) do not have a security field, so we
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* maintain a table associating each interface with a SID.
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*
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* Author: James Morris <jmorris@redhat.com>
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*
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* Copyright (C) 2003 Red Hat, Inc., James Morris <jmorris@redhat.com>
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* Copyright (C) 2007 Hewlett-Packard Development Company, L.P.
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* Paul Moore <paul.moore@hp.com>
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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,
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* as published by the Free Software Foundation.
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*/
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#include <linux/init.h>
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#include <linux/types.h>
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#include <linux/stddef.h>
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#include <linux/kernel.h>
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#include <linux/list.h>
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#include <linux/notifier.h>
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#include <linux/netdevice.h>
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#include <linux/rcupdate.h>
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#include <net/net_namespace.h>
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#include "security.h"
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#include "objsec.h"
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#include "netif.h"
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#define SEL_NETIF_HASH_SIZE 64
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#define SEL_NETIF_HASH_MAX 1024
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struct sel_netif {
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struct list_head list;
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struct netif_security_struct nsec;
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struct rcu_head rcu_head;
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};
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static u32 sel_netif_total;
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static LIST_HEAD(sel_netif_list);
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static DEFINE_SPINLOCK(sel_netif_lock);
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static struct list_head sel_netif_hash[SEL_NETIF_HASH_SIZE];
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/**
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* sel_netif_hashfn - Hashing function for the interface table
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* @ifindex: the network interface
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*
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* Description:
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* This is the hashing function for the network interface table, it returns the
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* bucket number for the given interface.
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*
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*/
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static inline u32 sel_netif_hashfn(int ifindex)
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{
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return (ifindex & (SEL_NETIF_HASH_SIZE - 1));
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}
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/**
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* sel_netif_find - Search for an interface record
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* @ifindex: the network interface
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*
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* Description:
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* Search the network interface table and return the record matching @ifindex.
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* If an entry can not be found in the table return NULL.
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*
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*/
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static inline struct sel_netif *sel_netif_find(int ifindex)
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{
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int idx = sel_netif_hashfn(ifindex);
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struct sel_netif *netif;
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list_for_each_entry_rcu(netif, &sel_netif_hash[idx], list)
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/* all of the devices should normally fit in the hash, so we
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* optimize for that case */
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if (likely(netif->nsec.ifindex == ifindex))
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return netif;
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return NULL;
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}
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/**
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* sel_netif_insert - Insert a new interface into the table
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* @netif: the new interface record
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*
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* Description:
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* Add a new interface record to the network interface hash table. Returns
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* zero on success, negative values on failure.
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*
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*/
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static int sel_netif_insert(struct sel_netif *netif)
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{
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int idx;
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if (sel_netif_total >= SEL_NETIF_HASH_MAX)
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return -ENOSPC;
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idx = sel_netif_hashfn(netif->nsec.ifindex);
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list_add_rcu(&netif->list, &sel_netif_hash[idx]);
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sel_netif_total++;
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return 0;
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}
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/**
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* sel_netif_free - Frees an interface 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 interface entry can be
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* released safely.
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*
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*/
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static void sel_netif_free(struct rcu_head *p)
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{
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struct sel_netif *netif = container_of(p, struct sel_netif, rcu_head);
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kfree(netif);
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}
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/**
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* sel_netif_destroy - Remove an interface record from the table
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* @netif: the existing interface record
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*
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* Description:
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* Remove an existing interface record from the network interface table.
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*
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*/
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static void sel_netif_destroy(struct sel_netif *netif)
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{
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list_del_rcu(&netif->list);
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sel_netif_total--;
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call_rcu(&netif->rcu_head, sel_netif_free);
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}
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/**
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* sel_netif_sid_slow - Lookup the SID of a network interface using the policy
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* @ifindex: the network interface
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* @sid: interface SID
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*
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* Description:
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* This function determines the SID of a network interface by quering the
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* security policy. The result is added to the network interface 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_netif_sid_slow(int ifindex, u32 *sid)
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{
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int ret;
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struct sel_netif *netif;
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struct sel_netif *new = NULL;
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struct net_device *dev;
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/* NOTE: we always use init's network namespace since we don't
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* currently support containers */
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dev = dev_get_by_index(&init_net, ifindex);
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if (unlikely(dev == NULL)) {
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printk(KERN_WARNING
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"SELinux: failure in sel_netif_sid_slow(),"
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" invalid network interface (%d)\n", ifindex);
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return -ENOENT;
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}
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spin_lock_bh(&sel_netif_lock);
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netif = sel_netif_find(ifindex);
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if (netif != NULL) {
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*sid = netif->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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ret = security_netif_sid(dev->name, &new->nsec.sid);
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if (ret != 0)
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goto out;
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new->nsec.ifindex = ifindex;
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ret = sel_netif_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_netif_lock);
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dev_put(dev);
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if (unlikely(ret)) {
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printk(KERN_WARNING
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"SELinux: failure in sel_netif_sid_slow(),"
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" unable to determine network interface label (%d)\n",
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ifindex);
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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_netif_sid - Lookup the SID of a network interface
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* @ifindex: the network interface
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* @sid: interface SID
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*
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* Description:
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* This function determines the SID of a network interface using the fastest
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* method possible. First the interface 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_netif_sid(int ifindex, u32 *sid)
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{
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struct sel_netif *netif;
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rcu_read_lock();
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netif = sel_netif_find(ifindex);
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if (likely(netif != NULL)) {
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*sid = netif->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_netif_sid_slow(ifindex, sid);
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}
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/**
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* sel_netif_kill - Remove an entry from the network interface table
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* @ifindex: the network interface
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*
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* Description:
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* This function removes the entry matching @ifindex from the network interface
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* table if it exists.
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*
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*/
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static void sel_netif_kill(int ifindex)
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{
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struct sel_netif *netif;
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rcu_read_lock();
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spin_lock_bh(&sel_netif_lock);
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netif = sel_netif_find(ifindex);
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if (netif)
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sel_netif_destroy(netif);
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spin_unlock_bh(&sel_netif_lock);
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rcu_read_unlock();
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}
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/**
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* sel_netif_flush - Flush the entire network interface table
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*
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* Description:
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* Remove all entries from the network interface table.
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*
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*/
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static void sel_netif_flush(void)
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{
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int idx;
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struct sel_netif *netif;
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spin_lock_bh(&sel_netif_lock);
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for (idx = 0; idx < SEL_NETIF_HASH_SIZE; idx++)
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list_for_each_entry(netif, &sel_netif_hash[idx], list)
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sel_netif_destroy(netif);
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spin_unlock_bh(&sel_netif_lock);
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}
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static int sel_netif_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_netif_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 int sel_netif_netdev_notifier_handler(struct notifier_block *this,
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unsigned long event, void *ptr)
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{
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struct net_device *dev = ptr;
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if (dev_net(dev) != &init_net)
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return NOTIFY_DONE;
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if (event == NETDEV_DOWN)
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sel_netif_kill(dev->ifindex);
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return NOTIFY_DONE;
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}
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static struct notifier_block sel_netif_netdev_notifier = {
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.notifier_call = sel_netif_netdev_notifier_handler,
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};
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static __init int sel_netif_init(void)
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{
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int i, err;
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if (!selinux_enabled)
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return 0;
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for (i = 0; i < SEL_NETIF_HASH_SIZE; i++)
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INIT_LIST_HEAD(&sel_netif_hash[i]);
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register_netdevice_notifier(&sel_netif_netdev_notifier);
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err = avc_add_callback(sel_netif_avc_callback, AVC_CALLBACK_RESET,
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SECSID_NULL, SECSID_NULL, SECCLASS_NULL, 0);
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if (err)
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panic("avc_add_callback() failed, error %d\n", err);
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return err;
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}
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__initcall(sel_netif_init);
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