linux/security/selinux/netif.c

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/*
* Network interface table.
*
* Network interfaces (devices) do not have a security field, so we
* maintain a table associating each interface with a SID.
*
* Author: James Morris <jmorris@redhat.com>
*
* Copyright (C) 2003 Red Hat, Inc., James Morris <jmorris@redhat.com>
* Copyright (C) 2007 Hewlett-Packard Development Company, L.P.
* Paul Moore <paul.moore@hp.com>
*
* 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/init.h>
#include <linux/types.h>
include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h percpu.h is included by sched.h and module.h and thus ends up being included when building most .c files. percpu.h includes slab.h which in turn includes gfp.h making everything defined by the two files universally available and complicating inclusion dependencies. percpu.h -> slab.h dependency is about to be removed. Prepare for this change by updating users of gfp and slab facilities include those headers directly instead of assuming availability. As this conversion needs to touch large number of source files, the following script is used as the basis of conversion. http://userweb.kernel.org/~tj/misc/slabh-sweep.py The script does the followings. * Scan files for gfp and slab usages and update includes such that only the necessary includes are there. ie. if only gfp is used, gfp.h, if slab is used, slab.h. * When the script inserts a new include, it looks at the include blocks and try to put the new include such that its order conforms to its surrounding. It's put in the include block which contains core kernel includes, in the same order that the rest are ordered - alphabetical, Christmas tree, rev-Xmas-tree or at the end if there doesn't seem to be any matching order. * If the script can't find a place to put a new include (mostly because the file doesn't have fitting include block), it prints out an error message indicating which .h file needs to be added to the file. The conversion was done in the following steps. 1. The initial automatic conversion of all .c files updated slightly over 4000 files, deleting around 700 includes and adding ~480 gfp.h and ~3000 slab.h inclusions. The script emitted errors for ~400 files. 2. Each error was manually checked. Some didn't need the inclusion, some needed manual addition while adding it to implementation .h or embedding .c file was more appropriate for others. This step added inclusions to around 150 files. 3. The script was run again and the output was compared to the edits from #2 to make sure no file was left behind. 4. Several build tests were done and a couple of problems were fixed. e.g. lib/decompress_*.c used malloc/free() wrappers around slab APIs requiring slab.h to be added manually. 5. The script was run on all .h files but without automatically editing them as sprinkling gfp.h and slab.h inclusions around .h files could easily lead to inclusion dependency hell. Most gfp.h inclusion directives were ignored as stuff from gfp.h was usually wildly available and often used in preprocessor macros. Each slab.h inclusion directive was examined and added manually as necessary. 6. percpu.h was updated not to include slab.h. 7. Build test were done on the following configurations and failures were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my distributed build env didn't work with gcov compiles) and a few more options had to be turned off depending on archs to make things build (like ipr on powerpc/64 which failed due to missing writeq). * x86 and x86_64 UP and SMP allmodconfig and a custom test config. * powerpc and powerpc64 SMP allmodconfig * sparc and sparc64 SMP allmodconfig * ia64 SMP allmodconfig * s390 SMP allmodconfig * alpha SMP allmodconfig * um on x86_64 SMP allmodconfig 8. percpu.h modifications were reverted so that it could be applied as a separate patch and serve as bisection point. Given the fact that I had only a couple of failures from tests on step 6, I'm fairly confident about the coverage of this conversion patch. If there is a breakage, it's likely to be something in one of the arch headers which should be easily discoverable easily on most builds of the specific arch. Signed-off-by: Tejun Heo <tj@kernel.org> Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2010-03-24 09:04:11 +01:00
#include <linux/slab.h>
#include <linux/stddef.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/notifier.h>
#include <linux/netdevice.h>
#include <linux/rcupdate.h>
#include <net/net_namespace.h>
#include "security.h"
#include "objsec.h"
#include "netif.h"
#define SEL_NETIF_HASH_SIZE 64
#define SEL_NETIF_HASH_MAX 1024
struct sel_netif {
struct list_head list;
struct netif_security_struct nsec;
struct rcu_head rcu_head;
};
static u32 sel_netif_total;
static LIST_HEAD(sel_netif_list);
static DEFINE_SPINLOCK(sel_netif_lock);
static struct list_head sel_netif_hash[SEL_NETIF_HASH_SIZE];
/**
* sel_netif_hashfn - Hashing function for the interface table
* @ifindex: the network interface
*
* Description:
* This is the hashing function for the network interface table, it returns the
* bucket number for the given interface.
*
*/
static inline u32 sel_netif_hashfn(int ifindex)
{
return (ifindex & (SEL_NETIF_HASH_SIZE - 1));
}
/**
* sel_netif_find - Search for an interface record
* @ifindex: the network interface
*
* Description:
* Search the network interface table and return the record matching @ifindex.
* If an entry can not be found in the table return NULL.
*
*/
static inline struct sel_netif *sel_netif_find(int ifindex)
{
int idx = sel_netif_hashfn(ifindex);
struct sel_netif *netif;
list_for_each_entry_rcu(netif, &sel_netif_hash[idx], list)
/* all of the devices should normally fit in the hash, so we
* optimize for that case */
if (likely(netif->nsec.ifindex == ifindex))
return netif;
return NULL;
}
/**
* sel_netif_insert - Insert a new interface into the table
* @netif: the new interface record
*
* Description:
* Add a new interface record to the network interface hash table. Returns
* zero on success, negative values on failure.
*
*/
static int sel_netif_insert(struct sel_netif *netif)
{
int idx;
if (sel_netif_total >= SEL_NETIF_HASH_MAX)
return -ENOSPC;
idx = sel_netif_hashfn(netif->nsec.ifindex);
list_add_rcu(&netif->list, &sel_netif_hash[idx]);
sel_netif_total++;
return 0;
}
/**
* sel_netif_free - Frees an interface entry
* @p: the entry's RCU field
*
* Description:
* This function is designed to be used as a callback to the call_rcu()
* function so that memory allocated to a hash table interface entry can be
* released safely.
*
*/
static void sel_netif_free(struct rcu_head *p)
{
struct sel_netif *netif = container_of(p, struct sel_netif, rcu_head);
kfree(netif);
}
/**
* sel_netif_destroy - Remove an interface record from the table
* @netif: the existing interface record
*
* Description:
* Remove an existing interface record from the network interface table.
*
*/
static void sel_netif_destroy(struct sel_netif *netif)
{
list_del_rcu(&netif->list);
sel_netif_total--;
call_rcu(&netif->rcu_head, sel_netif_free);
}
/**
* sel_netif_sid_slow - Lookup the SID of a network interface using the policy
* @ifindex: the network interface
* @sid: interface SID
*
* Description:
* This function determines the SID of a network interface by quering the
* security policy. The result is added to the network interface table to
* speedup future queries. Returns zero on success, negative values on
* failure.
*
*/
static int sel_netif_sid_slow(int ifindex, u32 *sid)
{
int ret;
struct sel_netif *netif;
struct sel_netif *new = NULL;
struct net_device *dev;
/* NOTE: we always use init's network namespace since we don't
* currently support containers */
dev = dev_get_by_index(&init_net, ifindex);
if (unlikely(dev == NULL)) {
printk(KERN_WARNING
"SELinux: failure in sel_netif_sid_slow(),"
" invalid network interface (%d)\n", ifindex);
return -ENOENT;
}
spin_lock_bh(&sel_netif_lock);
netif = sel_netif_find(ifindex);
if (netif != NULL) {
*sid = netif->nsec.sid;
ret = 0;
goto out;
}
new = kzalloc(sizeof(*new), GFP_ATOMIC);
if (new == NULL) {
ret = -ENOMEM;
goto out;
}
ret = security_netif_sid(dev->name, &new->nsec.sid);
if (ret != 0)
goto out;
new->nsec.ifindex = ifindex;
ret = sel_netif_insert(new);
if (ret != 0)
goto out;
*sid = new->nsec.sid;
out:
spin_unlock_bh(&sel_netif_lock);
dev_put(dev);
if (unlikely(ret)) {
printk(KERN_WARNING
"SELinux: failure in sel_netif_sid_slow(),"
" unable to determine network interface label (%d)\n",
ifindex);
kfree(new);
}
return ret;
}
/**
* sel_netif_sid - Lookup the SID of a network interface
* @ifindex: the network interface
* @sid: interface SID
*
* Description:
* This function determines the SID of a network interface using the fastest
* method possible. First the interface table is queried, but if an entry
* can't be found then the policy is queried and the result is added to the
* table to speedup future queries. Returns zero on success, negative values
* on failure.
*
*/
int sel_netif_sid(int ifindex, u32 *sid)
{
struct sel_netif *netif;
rcu_read_lock();
netif = sel_netif_find(ifindex);
if (likely(netif != NULL)) {
*sid = netif->nsec.sid;
rcu_read_unlock();
return 0;
}
rcu_read_unlock();
return sel_netif_sid_slow(ifindex, sid);
}
/**
* sel_netif_kill - Remove an entry from the network interface table
* @ifindex: the network interface
*
* Description:
* This function removes the entry matching @ifindex from the network interface
* table if it exists.
*
*/
static void sel_netif_kill(int ifindex)
{
struct sel_netif *netif;
rcu_read_lock();
spin_lock_bh(&sel_netif_lock);
netif = sel_netif_find(ifindex);
if (netif)
sel_netif_destroy(netif);
spin_unlock_bh(&sel_netif_lock);
rcu_read_unlock();
}
/**
* sel_netif_flush - Flush the entire network interface table
*
* Description:
* Remove all entries from the network interface table.
*
*/
static void sel_netif_flush(void)
{
int idx;
struct sel_netif *netif;
spin_lock_bh(&sel_netif_lock);
for (idx = 0; idx < SEL_NETIF_HASH_SIZE; idx++)
list_for_each_entry(netif, &sel_netif_hash[idx], list)
sel_netif_destroy(netif);
spin_unlock_bh(&sel_netif_lock);
}
static int sel_netif_avc_callback(u32 event, u32 ssid, u32 tsid,
u16 class, u32 perms, u32 *retained)
{
if (event == AVC_CALLBACK_RESET) {
sel_netif_flush();
synchronize_net();
}
return 0;
}
static int sel_netif_netdev_notifier_handler(struct notifier_block *this,
unsigned long event, void *ptr)
{
struct net_device *dev = ptr;
if (dev_net(dev) != &init_net)
return NOTIFY_DONE;
if (event == NETDEV_DOWN)
sel_netif_kill(dev->ifindex);
return NOTIFY_DONE;
}
static struct notifier_block sel_netif_netdev_notifier = {
.notifier_call = sel_netif_netdev_notifier_handler,
};
static __init int sel_netif_init(void)
{
int i, err;
if (!selinux_enabled)
return 0;
for (i = 0; i < SEL_NETIF_HASH_SIZE; i++)
INIT_LIST_HEAD(&sel_netif_hash[i]);
register_netdevice_notifier(&sel_netif_netdev_notifier);
err = avc_add_callback(sel_netif_avc_callback, AVC_CALLBACK_RESET,
SECSID_NULL, SECSID_NULL, SECCLASS_NULL, 0);
if (err)
panic("avc_add_callback() failed, error %d\n", err);
return err;
}
__initcall(sel_netif_init);