/*
* NetLabel Domain Hash Table
*
* This file manages the domain hash table that NetLabel uses to determine
* which network labeling protocol to use for a given domain. The NetLabel
* system manages static and dynamic label mappings for network protocols such
* as CIPSO and RIPSO.
*
* Author: Paul Moore <paul.moore@hp.com>
*
*/
/*
* (c) Copyright Hewlett-Packard Development Company, L.P., 2006
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
* the GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
#include <linux/types.h>
#include <linux/rcupdate.h>
#include <linux/list.h>
#include <linux/skbuff.h>
#include <linux/spinlock.h>
#include <linux/string.h>
#include <net/netlabel.h>
#include <net/cipso_ipv4.h>
#include <asm/bug.h>
#include "netlabel_mgmt.h"
#include "netlabel_domainhash.h"
struct netlbl_domhsh_tbl {
struct list_head *tbl;
u32 size;
};
/* Domain hash table */
/* XXX - updates should be so rare that having one spinlock for the entire
* hash table should be okay */
static DEFINE_SPINLOCK(netlbl_domhsh_lock);
static struct netlbl_domhsh_tbl *netlbl_domhsh = NULL;
/* Default domain mapping */
static DEFINE_SPINLOCK(netlbl_domhsh_def_lock);
static struct netlbl_dom_map *netlbl_domhsh_def = NULL;
/*
* Domain Hash Table Helper Functions
*/
/**
* netlbl_domhsh_free_entry - Frees a domain hash table entry
* @entry: the entry's RCU field
*
* Description:
* This function is designed to be used as a callback to the call_rcu()
* function so that the memory allocated to a hash table entry can be released
* safely.
*
*/
static void netlbl_domhsh_free_entry(struct rcu_head *entry)
{
struct netlbl_dom_map *ptr;
ptr = container_of(entry, struct netlbl_dom_map, rcu);
kfree(ptr->domain);
kfree(ptr);
}
/**
* netlbl_domhsh_hash - Hashing function for the domain hash table
* @domain: the domain name to hash
*
* Description:
* This is the hashing function for the domain hash table, it returns the
* correct bucket number for the domain. The caller is responsibile for
* calling the rcu_read_[un]lock() functions.
*
*/
static u32 netlbl_domhsh_hash(const char *key)
{
u32 iter;
u32 val;
u32 len;
/* This is taken (with slight modification) from
* security/selinux/ss/symtab.c:symhash() */
for (iter = 0, val = 0, len = strlen(key); iter < len; iter++)
val = (val << 4 | (val >> (8 * sizeof(u32) - 4))) ^ key[iter];
return val & (rcu_dereference(netlbl_domhsh)->size - 1);
}
/**
* netlbl_domhsh_search - Search for a domain entry
* @domain: the domain
* @def: return default if no match is found
*
* Description:
* Searches the domain hash table and returns a pointer to the hash table
* entry if found, otherwise NULL is returned. If @def is non-zero and a
* match is not found in the domain hash table the default mapping is returned
* if it exists. The caller is responsibile for the rcu hash table locks
* (i.e. the caller much call rcu_read_[un]lock()).
*
*/
static struct netlbl_dom_map *netlbl_domhsh_search(const char *domain, u32 def)
{
u32 bkt;
struct netlbl_dom_map *iter;
if (domain != NULL) {
bkt = netlbl_domhsh_hash(domain);
list_for_each_entry_rcu(iter, &netlbl_domhsh->tbl[bkt], list)
if (iter->valid && strcmp(iter->domain, domain) == 0)
return iter;
}
if (def != 0) {
iter = rcu_dereference(netlbl_domhsh_def);
if (iter != NULL && iter->valid)
return iter;
}
return NULL;
}
/*
* Domain Hash Table Functions
*/
/**
* netlbl_domhsh_init - Init for the domain hash
* @size: the number of bits to use for the hash buckets
*
* Description:
* Initializes the domain hash table, should be called only by
* netlbl_user_init() during initialization. Returns zero on success, non-zero
* values on error.
*
*/
int netlbl_domhsh_init(u32 size)
{
u32 iter;
struct netlbl_domhsh_tbl *hsh_tbl;
if (size == 0)
return -EINVAL;
hsh_tbl = kmalloc(sizeof(*hsh_tbl), GFP_KERNEL);
if (hsh_tbl == NULL)
return -ENOMEM;
hsh_tbl->size = 1 << size;
hsh_tbl->tbl = kcalloc(hsh_tbl->size,
sizeof(struct list_head),
GFP_KERNEL);
if (hsh_tbl->tbl == NULL) {
kfree(hsh_tbl);
return -ENOMEM;
}
for (iter = 0; iter < hsh_tbl->size; iter++)
INIT_LIST_HEAD(&hsh_tbl->tbl[iter]);
rcu_read_lock();
spin_lock(&netlbl_domhsh_lock);
rcu_assign_pointer(netlbl_domhsh, hsh_tbl);
spin_unlock(&netlbl_domhsh_lock);
rcu_read_unlock();
return 0;
}
/**
* netlbl_domhsh_add - Adds a entry to the domain hash table
* @entry: the entry to add
*
* Description:
* Adds a new entry to the domain hash table and handles any updates to the
* lower level protocol handler (i.e. CIPSO). Returns zero on success,
* negative on failure.
*
*/
int netlbl_domhsh_add(struct netlbl_dom_map *entry)
{
int ret_val;
u32 bkt;
switch (entry->type) {
case NETLBL_NLTYPE_UNLABELED:
ret_val = 0;
break;
case NETLBL_NLTYPE_CIPSOV4:
ret_val = cipso_v4_doi_domhsh_add(entry->type_def.cipsov4,
entry->domain);
break;
default:
return -EINVAL;
}
if (ret_val != 0)
return ret_val;
entry->valid = 1;
INIT_RCU_HEAD(&entry->rcu);
ret_val = 0;
rcu_read_lock();
if (entry->domain != NULL) {
bkt = netlbl_domhsh_hash(entry->domain);
spin_lock(&netlbl_domhsh_lock);
if (netlbl_domhsh_search(entry->domain, 0) == NULL)
list_add_tail_rcu(&entry->list,
&netlbl_domhsh->tbl[bkt]);
else
ret_val = -EEXIST;
spin_unlock(&netlbl_domhsh_lock);
} else if (entry->domain == NULL) {
INIT_LIST_HEAD(&entry->list);
spin_lock(&netlbl_domhsh_def_lock);
if (rcu_dereference(netlbl_domhsh_def) == NULL)
rcu_assign_pointer(netlbl_domhsh_def, entry);
else
ret_val = -EEXIST;
spin_unlock(&netlbl_domhsh_def_lock);
} else
ret_val = -EINVAL;
rcu_read_unlock();
if (ret_val != 0) {
switch (entry->type) {
case NETLBL_NLTYPE_CIPSOV4:
if (cipso_v4_doi_domhsh_remove(entry->type_def.cipsov4,
entry->domain) != 0)
BUG();
break;
}
}
return ret_val;
}
/**
* netlbl_domhsh_add_default - Adds the default entry to the domain hash table
* @entry: the entry to add
*
* Description:
* Adds a new default entry to the domain hash table and handles any updates
* to the lower level protocol handler (i.e. CIPSO). Returns zero on success,
* negative on failure.
*
*/
int netlbl_domhsh_add_default(struct netlbl_dom_map *entry)
{
return netlbl_domhsh_add(entry);
}
/**
* netlbl_domhsh_remove - Removes an entry from the domain hash table
* @domain: the domain to remove
*
* Description:
* Removes an entry from the domain hash table and handles any updates to the
* lower level protocol handler (i.e. CIPSO). Returns zero on success,
* negative on failure.
*
*/
int netlbl_domhsh_remove(const char *domain)
{
int ret_val = -ENOENT;
struct netlbl_dom_map *entry;
rcu_read_lock();
if (domain != NULL)
entry = netlbl_domhsh_search(domain, 0);
else
entry = netlbl_domhsh_search(domain, 1);
if (entry == NULL)
goto remove_return;
switch (entry->type) {
case NETLBL_NLTYPE_UNLABELED:
break;
case NETLBL_NLTYPE_CIPSOV4:
ret_val = cipso_v4_doi_domhsh_remove(entry->type_def.cipsov4,
entry->domain);
if (ret_val != 0)
goto remove_return;
break;
}
ret_val = 0;
if (entry != rcu_dereference(netlbl_domhsh_def)) {
spin_lock(&netlbl_domhsh_lock);
if (entry->valid) {
entry->valid = 0;
list_del_rcu(&entry->list);
} else
ret_val = -ENOENT;
spin_unlock(&netlbl_domhsh_lock);
} else {
spin_lock(&netlbl_domhsh_def_lock);
if (entry->valid) {
entry->valid = 0;
rcu_assign_pointer(netlbl_domhsh_def, NULL);
} else
ret_val = -ENOENT;
spin_unlock(&netlbl_domhsh_def_lock);
}
if (ret_val == 0)
call_rcu(&entry->rcu, netlbl_domhsh_free_entry);
remove_return:
rcu_read_unlock();
return ret_val;
}
/**
* netlbl_domhsh_remove_default - Removes the default entry from the table
*
* Description:
* Removes/resets the default entry for the domain hash table and handles any
* updates to the lower level protocol handler (i.e. CIPSO). Returns zero on
* success, non-zero on failure.
*
*/
int netlbl_domhsh_remove_default(void)
{
return netlbl_domhsh_remove(NULL);
}
/**
* netlbl_domhsh_getentry - Get an entry from the domain hash table
* @domain: the domain name to search for
*
* Description:
* Look through the domain hash table searching for an entry to match @domain,
* return a pointer to a copy of the entry or NULL. The caller is responsibile
* for ensuring that rcu_read_[un]lock() is called.
*
*/
struct netlbl_dom_map *netlbl_domhsh_getentry(const char *domain)
{
return netlbl_domhsh_search(domain, 1);
}
/**
* netlbl_domhsh_walk - Iterate through the domain mapping hash table
* @skip_bkt: the number of buckets to skip at the start
* @skip_chain: the number of entries to skip in the first iterated bucket
* @callback: callback for each entry
* @cb_arg: argument for the callback function
*
* Description:
* Interate over the domain mapping hash table, skipping the first @skip_bkt
* buckets and @skip_chain entries. For each entry in the table call
* @callback, if @callback returns a negative value stop 'walking' through the
* table and return. Updates the values in @skip_bkt and @skip_chain on
* return. Returns zero on succcess, negative values on failure.
*
*/
int netlbl_domhsh_walk(u32 *skip_bkt,
u32 *skip_chain,
int (*callback) (struct netlbl_dom_map *entry, void *arg),
void *cb_arg)
{
int ret_val = -ENOENT;
u32 iter_bkt;
struct netlbl_dom_map *iter_entry;
u32 chain_cnt = 0;
rcu_read_lock();
for (iter_bkt = *skip_bkt;
iter_bkt < rcu_dereference(netlbl_domhsh)->size;
iter_bkt++, chain_cnt = 0) {
list_for_each_entry_rcu(iter_entry,
&netlbl_domhsh->tbl[iter_bkt],
list)
if (iter_entry->valid) {
if (chain_cnt++ < *skip_chain)
continue;
ret_val = callback(iter_entry, cb_arg);
if (ret_val < 0) {
chain_cnt--;
goto walk_return;
}
}
}
walk_return:
rcu_read_unlock();
*skip_bkt = iter_bkt;
*skip_chain = chain_cnt;
return ret_val;
}
