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SELinux: Made netnode cache adds faster
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When adding new entries to the network node cache we would walk the entire
hash bucket to make sure we didn't cross a threshold (done to bound the
cache size).  This isn't a very quick or elegant solution for something
which is supposed to be quick-ish so add a counter to each hash bucket to
track the size of the bucket and eliminate the need to walk the entire
bucket list on each add.

Signed-off-by: Paul Moore <paul.moore@hp.com>
Signed-off-by: James Morris <jmorris@namei.org>
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Paul Moore authored and James Morris committed Apr 27, 2008
1 parent 7b41b17 commit a639e7c
Showing 1 changed file with 49 additions and 55 deletions.
104 changes: 49 additions & 55 deletions security/selinux/netnode.c
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Original file line number Diff line number Diff line change
Expand Up @@ -40,11 +40,17 @@
#include <net/ipv6.h>
#include <asm/bug.h>

#include "netnode.h"
#include "objsec.h"

#define SEL_NETNODE_HASH_SIZE 256
#define SEL_NETNODE_HASH_BKT_LIMIT 16

struct sel_netnode_bkt {
unsigned int size;
struct list_head list;
};

struct sel_netnode {
struct netnode_security_struct nsec;

Expand All @@ -60,7 +66,7 @@ struct sel_netnode {

static LIST_HEAD(sel_netnode_list);
static DEFINE_SPINLOCK(sel_netnode_lock);
static struct list_head sel_netnode_hash[SEL_NETNODE_HASH_SIZE];
static struct sel_netnode_bkt sel_netnode_hash[SEL_NETNODE_HASH_SIZE];

/**
* sel_netnode_free - Frees a node entry
Expand All @@ -87,7 +93,7 @@ static void sel_netnode_free(struct rcu_head *p)
* the bucket number for the given IP address.
*
*/
static u32 sel_netnode_hashfn_ipv4(__be32 addr)
static unsigned int sel_netnode_hashfn_ipv4(__be32 addr)
{
/* at some point we should determine if the mismatch in byte order
* affects the hash function dramatically */
Expand All @@ -103,7 +109,7 @@ static u32 sel_netnode_hashfn_ipv4(__be32 addr)
* the bucket number for the given IP address.
*
*/
static u32 sel_netnode_hashfn_ipv6(const struct in6_addr *addr)
static unsigned int sel_netnode_hashfn_ipv6(const struct in6_addr *addr)
{
/* just hash the least significant 32 bits to keep things fast (they
* are the most likely to be different anyway), we can revisit this
Expand All @@ -123,7 +129,7 @@ static u32 sel_netnode_hashfn_ipv6(const struct in6_addr *addr)
*/
static struct sel_netnode *sel_netnode_find(const void *addr, u16 family)
{
u32 idx;
unsigned int idx;
struct sel_netnode *node;

switch (family) {
Expand All @@ -137,7 +143,7 @@ static struct sel_netnode *sel_netnode_find(const void *addr, u16 family)
BUG();
}

list_for_each_entry_rcu(node, &sel_netnode_hash[idx], list)
list_for_each_entry_rcu(node, &sel_netnode_hash[idx].list, list)
if (node->nsec.family == family)
switch (family) {
case PF_INET:
Expand All @@ -159,15 +165,12 @@ static struct sel_netnode *sel_netnode_find(const void *addr, u16 family)
* @node: the new node record
*
* Description:
* Add a new node record to the network address hash table. Returns zero on
* success, negative values on failure.
* Add a new node record to the network address hash table.
*
*/
static int sel_netnode_insert(struct sel_netnode *node)
static void sel_netnode_insert(struct sel_netnode *node)
{
u32 idx;
u32 count = 0;
struct sel_netnode *iter;
unsigned int idx;

switch (node->nsec.family) {
case PF_INET:
Expand All @@ -179,32 +182,21 @@ static int sel_netnode_insert(struct sel_netnode *node)
default:
BUG();
}
list_add_rcu(&node->list, &sel_netnode_hash[idx]);

INIT_RCU_HEAD(&node->rcu);

/* we need to impose a limit on the growth of the hash table so check
* this bucket to make sure it is within the specified bounds */
list_for_each_entry(iter, &sel_netnode_hash[idx], list)
if (++count > SEL_NETNODE_HASH_BKT_LIMIT) {
list_del_rcu(&iter->list);
call_rcu(&iter->rcu, sel_netnode_free);
break;
}

return 0;
}

/**
* sel_netnode_destroy - Remove a node record from the table
* @node: the existing node record
*
* Description:
* Remove an existing node record from the network address table.
*
*/
static void sel_netnode_destroy(struct sel_netnode *node)
{
list_del_rcu(&node->list);
call_rcu(&node->rcu, sel_netnode_free);
list_add_rcu(&node->list, &sel_netnode_hash[idx].list);
if (sel_netnode_hash[idx].size == SEL_NETNODE_HASH_BKT_LIMIT) {
struct sel_netnode *tail;
tail = list_entry(
rcu_dereference(sel_netnode_hash[idx].list.prev),
struct sel_netnode, list);
list_del_rcu(&tail->list);
call_rcu(&tail->rcu, sel_netnode_free);
} else
sel_netnode_hash[idx].size++;
}

/**
Expand All @@ -222,45 +214,40 @@ static void sel_netnode_destroy(struct sel_netnode *node)
*/
static int sel_netnode_sid_slow(void *addr, u16 family, u32 *sid)
{
int ret;
int ret = -ENOMEM;
struct sel_netnode *node;
struct sel_netnode *new = NULL;

spin_lock_bh(&sel_netnode_lock);
node = sel_netnode_find(addr, family);
if (node != NULL) {
*sid = node->nsec.sid;
ret = 0;
goto out;
spin_unlock_bh(&sel_netnode_lock);
return 0;
}
new = kzalloc(sizeof(*new), GFP_ATOMIC);
if (new == NULL) {
ret = -ENOMEM;
if (new == NULL)
goto out;
}
switch (family) {
case PF_INET:
ret = security_node_sid(PF_INET,
addr, sizeof(struct in_addr),
&new->nsec.sid);
addr, sizeof(struct in_addr), sid);
new->nsec.addr.ipv4 = *(__be32 *)addr;
break;
case PF_INET6:
ret = security_node_sid(PF_INET6,
addr, sizeof(struct in6_addr),
&new->nsec.sid);
addr, sizeof(struct in6_addr), sid);
ipv6_addr_copy(&new->nsec.addr.ipv6, addr);
break;
default:
BUG();
}
if (ret != 0)
goto out;

new->nsec.family = family;
ret = sel_netnode_insert(new);
if (ret != 0)
goto out;
*sid = new->nsec.sid;
new->nsec.sid = *sid;
sel_netnode_insert(new);

out:
spin_unlock_bh(&sel_netnode_lock);
Expand Down Expand Up @@ -312,13 +299,18 @@ int sel_netnode_sid(void *addr, u16 family, u32 *sid)
*/
static void sel_netnode_flush(void)
{
u32 idx;
struct sel_netnode *node;
unsigned int idx;
struct sel_netnode *node, *node_tmp;

spin_lock_bh(&sel_netnode_lock);
for (idx = 0; idx < SEL_NETNODE_HASH_SIZE; idx++)
list_for_each_entry(node, &sel_netnode_hash[idx], list)
sel_netnode_destroy(node);
for (idx = 0; idx < SEL_NETNODE_HASH_SIZE; idx++) {
list_for_each_entry_safe(node, node_tmp,
&sel_netnode_hash[idx].list, list) {
list_del_rcu(&node->list);
call_rcu(&node->rcu, sel_netnode_free);
}
sel_netnode_hash[idx].size = 0;
}
spin_unlock_bh(&sel_netnode_lock);
}

Expand All @@ -340,8 +332,10 @@ static __init int sel_netnode_init(void)
if (!selinux_enabled)
return 0;

for (iter = 0; iter < SEL_NETNODE_HASH_SIZE; iter++)
INIT_LIST_HEAD(&sel_netnode_hash[iter]);
for (iter = 0; iter < SEL_NETNODE_HASH_SIZE; iter++) {
INIT_LIST_HEAD(&sel_netnode_hash[iter].list);
sel_netnode_hash[iter].size = 0;
}

ret = avc_add_callback(sel_netnode_avc_callback, AVC_CALLBACK_RESET,
SECSID_NULL, SECSID_NULL, SECCLASS_NULL, 0);
Expand Down

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