linux/net/netlabel/netlabel_kapi.c
Paul Moore 23bcdc1ade SELinux: enable dynamic activation/deactivation of NetLabel/SELinux enforcement
Create a new NetLabel KAPI interface, netlbl_enabled(), which reports on the
current runtime status of NetLabel based on the existing configuration.  LSMs
that make use of NetLabel, i.e. SELinux, can use this new function to determine
if they should perform NetLabel access checks.  This patch changes the
NetLabel/SELinux glue code such that SELinux only enforces NetLabel related
access checks when netlbl_enabled() returns true.

At present NetLabel is considered to be enabled when there is at least one
labeled protocol configuration present.  The result is that by default NetLabel
is considered to be disabled, however, as soon as an administrator configured
a CIPSO DOI definition NetLabel is enabled and SELinux starts enforcing
NetLabel related access controls - including unlabeled packet controls.

This patch also tries to consolidate the multiple "#ifdef CONFIG_NETLABEL"
blocks into a single block to ease future review as recommended by Linus.

Signed-off-by: Paul Moore <paul.moore@hp.com>
Signed-off-by: James Morris <jmorris@namei.org>
2007-07-19 10:21:11 -04:00

450 lines
12 KiB
C

/*
* NetLabel Kernel API
*
* This file defines the kernel API for the NetLabel system. 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/init.h>
#include <linux/types.h>
#include <net/ip.h>
#include <net/netlabel.h>
#include <net/cipso_ipv4.h>
#include <asm/bug.h>
#include "netlabel_domainhash.h"
#include "netlabel_unlabeled.h"
#include "netlabel_user.h"
#include "netlabel_mgmt.h"
/*
* Security Attribute Functions
*/
/**
* netlbl_secattr_catmap_walk - Walk a LSM secattr catmap looking for a bit
* @catmap: the category bitmap
* @offset: the offset to start searching at, in bits
*
* Description:
* This function walks a LSM secattr category bitmap starting at @offset and
* returns the spot of the first set bit or -ENOENT if no bits are set.
*
*/
int netlbl_secattr_catmap_walk(struct netlbl_lsm_secattr_catmap *catmap,
u32 offset)
{
struct netlbl_lsm_secattr_catmap *iter = catmap;
u32 node_idx;
u32 node_bit;
NETLBL_CATMAP_MAPTYPE bitmap;
if (offset > iter->startbit) {
while (offset >= (iter->startbit + NETLBL_CATMAP_SIZE)) {
iter = iter->next;
if (iter == NULL)
return -ENOENT;
}
node_idx = (offset - iter->startbit) / NETLBL_CATMAP_MAPSIZE;
node_bit = offset - iter->startbit -
(NETLBL_CATMAP_MAPSIZE * node_idx);
} else {
node_idx = 0;
node_bit = 0;
}
bitmap = iter->bitmap[node_idx] >> node_bit;
for (;;) {
if (bitmap != 0) {
while ((bitmap & NETLBL_CATMAP_BIT) == 0) {
bitmap >>= 1;
node_bit++;
}
return iter->startbit +
(NETLBL_CATMAP_MAPSIZE * node_idx) + node_bit;
}
if (++node_idx >= NETLBL_CATMAP_MAPCNT) {
if (iter->next != NULL) {
iter = iter->next;
node_idx = 0;
} else
return -ENOENT;
}
bitmap = iter->bitmap[node_idx];
node_bit = 0;
}
return -ENOENT;
}
/**
* netlbl_secattr_catmap_walk_rng - Find the end of a string of set bits
* @catmap: the category bitmap
* @offset: the offset to start searching at, in bits
*
* Description:
* This function walks a LSM secattr category bitmap starting at @offset and
* returns the spot of the first cleared bit or -ENOENT if the offset is past
* the end of the bitmap.
*
*/
int netlbl_secattr_catmap_walk_rng(struct netlbl_lsm_secattr_catmap *catmap,
u32 offset)
{
struct netlbl_lsm_secattr_catmap *iter = catmap;
u32 node_idx;
u32 node_bit;
NETLBL_CATMAP_MAPTYPE bitmask;
NETLBL_CATMAP_MAPTYPE bitmap;
if (offset > iter->startbit) {
while (offset >= (iter->startbit + NETLBL_CATMAP_SIZE)) {
iter = iter->next;
if (iter == NULL)
return -ENOENT;
}
node_idx = (offset - iter->startbit) / NETLBL_CATMAP_MAPSIZE;
node_bit = offset - iter->startbit -
(NETLBL_CATMAP_MAPSIZE * node_idx);
} else {
node_idx = 0;
node_bit = 0;
}
bitmask = NETLBL_CATMAP_BIT << node_bit;
for (;;) {
bitmap = iter->bitmap[node_idx];
while (bitmask != 0 && (bitmap & bitmask) != 0) {
bitmask <<= 1;
node_bit++;
}
if (bitmask != 0)
return iter->startbit +
(NETLBL_CATMAP_MAPSIZE * node_idx) +
node_bit - 1;
else if (++node_idx >= NETLBL_CATMAP_MAPCNT) {
if (iter->next == NULL)
return iter->startbit + NETLBL_CATMAP_SIZE - 1;
iter = iter->next;
node_idx = 0;
}
bitmask = NETLBL_CATMAP_BIT;
node_bit = 0;
}
return -ENOENT;
}
/**
* netlbl_secattr_catmap_setbit - Set a bit in a LSM secattr catmap
* @catmap: the category bitmap
* @bit: the bit to set
* @flags: memory allocation flags
*
* Description:
* Set the bit specified by @bit in @catmap. Returns zero on success,
* negative values on failure.
*
*/
int netlbl_secattr_catmap_setbit(struct netlbl_lsm_secattr_catmap *catmap,
u32 bit,
gfp_t flags)
{
struct netlbl_lsm_secattr_catmap *iter = catmap;
u32 node_bit;
u32 node_idx;
while (iter->next != NULL &&
bit >= (iter->startbit + NETLBL_CATMAP_SIZE))
iter = iter->next;
if (bit >= (iter->startbit + NETLBL_CATMAP_SIZE)) {
iter->next = netlbl_secattr_catmap_alloc(flags);
if (iter->next == NULL)
return -ENOMEM;
iter = iter->next;
iter->startbit = bit & ~(NETLBL_CATMAP_SIZE - 1);
}
/* gcc always rounds to zero when doing integer division */
node_idx = (bit - iter->startbit) / NETLBL_CATMAP_MAPSIZE;
node_bit = bit - iter->startbit - (NETLBL_CATMAP_MAPSIZE * node_idx);
iter->bitmap[node_idx] |= NETLBL_CATMAP_BIT << node_bit;
return 0;
}
/**
* netlbl_secattr_catmap_setrng - Set a range of bits in a LSM secattr catmap
* @catmap: the category bitmap
* @start: the starting bit
* @end: the last bit in the string
* @flags: memory allocation flags
*
* Description:
* Set a range of bits, starting at @start and ending with @end. Returns zero
* on success, negative values on failure.
*
*/
int netlbl_secattr_catmap_setrng(struct netlbl_lsm_secattr_catmap *catmap,
u32 start,
u32 end,
gfp_t flags)
{
int ret_val = 0;
struct netlbl_lsm_secattr_catmap *iter = catmap;
u32 iter_max_spot;
u32 spot;
/* XXX - This could probably be made a bit faster by combining writes
* to the catmap instead of setting a single bit each time, but for
* right now skipping to the start of the range in the catmap should
* be a nice improvement over calling the individual setbit function
* repeatedly from a loop. */
while (iter->next != NULL &&
start >= (iter->startbit + NETLBL_CATMAP_SIZE))
iter = iter->next;
iter_max_spot = iter->startbit + NETLBL_CATMAP_SIZE;
for (spot = start; spot <= end && ret_val == 0; spot++) {
if (spot >= iter_max_spot && iter->next != NULL) {
iter = iter->next;
iter_max_spot = iter->startbit + NETLBL_CATMAP_SIZE;
}
ret_val = netlbl_secattr_catmap_setbit(iter, spot, GFP_ATOMIC);
}
return ret_val;
}
/*
* LSM Functions
*/
/**
* netlbl_enabled - Determine if the NetLabel subsystem is enabled
*
* Description:
* The LSM can use this function to determine if it should use NetLabel
* security attributes in it's enforcement mechanism. Currently, NetLabel is
* considered to be enabled when it's configuration contains a valid setup for
* at least one labeled protocol (i.e. NetLabel can understand incoming
* labeled packets of at least one type); otherwise NetLabel is considered to
* be disabled.
*
*/
int netlbl_enabled(void)
{
/* At some point we probably want to expose this mechanism to the user
* as well so that admins can toggle NetLabel regardless of the
* configuration */
return (netlbl_mgmt_protocount_value() > 0 ? 1 : 0);
}
/**
* netlbl_socket_setattr - Label a socket using the correct protocol
* @sk: the socket to label
* @secattr: the security attributes
*
* Description:
* Attach the correct label to the given socket using the security attributes
* specified in @secattr. This function requires exclusive access to @sk,
* which means it either needs to be in the process of being created or locked.
* Returns zero on success, negative values on failure.
*
*/
int netlbl_sock_setattr(struct sock *sk,
const struct netlbl_lsm_secattr *secattr)
{
int ret_val = -ENOENT;
struct netlbl_dom_map *dom_entry;
rcu_read_lock();
dom_entry = netlbl_domhsh_getentry(secattr->domain);
if (dom_entry == NULL)
goto socket_setattr_return;
switch (dom_entry->type) {
case NETLBL_NLTYPE_CIPSOV4:
ret_val = cipso_v4_sock_setattr(sk,
dom_entry->type_def.cipsov4,
secattr);
break;
case NETLBL_NLTYPE_UNLABELED:
ret_val = 0;
break;
default:
ret_val = -ENOENT;
}
socket_setattr_return:
rcu_read_unlock();
return ret_val;
}
/**
* netlbl_sock_getattr - Determine the security attributes of a sock
* @sk: the sock
* @secattr: the security attributes
*
* Description:
* Examines the given sock to see any NetLabel style labeling has been
* applied to the sock, if so it parses the socket label and returns the
* security attributes in @secattr. Returns zero on success, negative values
* on failure.
*
*/
int netlbl_sock_getattr(struct sock *sk, struct netlbl_lsm_secattr *secattr)
{
int ret_val;
ret_val = cipso_v4_sock_getattr(sk, secattr);
if (ret_val == 0)
return 0;
return netlbl_unlabel_getattr(secattr);
}
/**
* netlbl_skbuff_getattr - Determine the security attributes of a packet
* @skb: the packet
* @secattr: the security attributes
*
* Description:
* Examines the given packet to see if a recognized form of packet labeling
* is present, if so it parses the packet label and returns the security
* attributes in @secattr. Returns zero on success, negative values on
* failure.
*
*/
int netlbl_skbuff_getattr(const struct sk_buff *skb,
struct netlbl_lsm_secattr *secattr)
{
if (CIPSO_V4_OPTEXIST(skb) &&
cipso_v4_skbuff_getattr(skb, secattr) == 0)
return 0;
return netlbl_unlabel_getattr(secattr);
}
/**
* netlbl_skbuff_err - Handle a LSM error on a sk_buff
* @skb: the packet
* @error: the error code
*
* Description:
* Deal with a LSM problem when handling the packet in @skb, typically this is
* a permission denied problem (-EACCES). The correct action is determined
* according to the packet's labeling protocol.
*
*/
void netlbl_skbuff_err(struct sk_buff *skb, int error)
{
if (CIPSO_V4_OPTEXIST(skb))
cipso_v4_error(skb, error, 0);
}
/**
* netlbl_cache_invalidate - Invalidate all of the NetLabel protocol caches
*
* Description:
* For all of the NetLabel protocols that support some form of label mapping
* cache, invalidate the cache. Returns zero on success, negative values on
* error.
*
*/
void netlbl_cache_invalidate(void)
{
cipso_v4_cache_invalidate();
}
/**
* netlbl_cache_add - Add an entry to a NetLabel protocol cache
* @skb: the packet
* @secattr: the packet's security attributes
*
* Description:
* Add the LSM security attributes for the given packet to the underlying
* NetLabel protocol's label mapping cache. Returns zero on success, negative
* values on error.
*
*/
int netlbl_cache_add(const struct sk_buff *skb,
const struct netlbl_lsm_secattr *secattr)
{
if ((secattr->flags & NETLBL_SECATTR_CACHE) == 0)
return -ENOMSG;
if (CIPSO_V4_OPTEXIST(skb))
return cipso_v4_cache_add(skb, secattr);
return -ENOMSG;
}
/*
* Setup Functions
*/
/**
* netlbl_init - Initialize NetLabel
*
* Description:
* Perform the required NetLabel initialization before first use.
*
*/
static int __init netlbl_init(void)
{
int ret_val;
printk(KERN_INFO "NetLabel: Initializing\n");
printk(KERN_INFO "NetLabel: domain hash size = %u\n",
(1 << NETLBL_DOMHSH_BITSIZE));
printk(KERN_INFO "NetLabel: protocols ="
" UNLABELED"
" CIPSOv4"
"\n");
ret_val = netlbl_domhsh_init(NETLBL_DOMHSH_BITSIZE);
if (ret_val != 0)
goto init_failure;
ret_val = netlbl_netlink_init();
if (ret_val != 0)
goto init_failure;
ret_val = netlbl_unlabel_defconf();
if (ret_val != 0)
goto init_failure;
printk(KERN_INFO "NetLabel: unlabeled traffic allowed by default\n");
return 0;
init_failure:
panic("NetLabel: failed to initialize properly (%d)\n", ret_val);
}
subsys_initcall(netlbl_init);