/*
* SELinux NetLabel Support
*
* This file provides the necessary glue to tie NetLabel into the SELinux
* subsystem.
*
* Author: Paul Moore <paul.moore@hp.com>
*
*/
/*
* (c) Copyright Hewlett-Packard Development Company, L.P., 2007, 2008
*
* 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/spinlock.h>
#include <linux/rcupdate.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <net/sock.h>
#include <net/netlabel.h>
#include <net/ip.h>
#include <net/ipv6.h>
#include "objsec.h"
#include "security.h"
#include "netlabel.h"
/**
* selinux_netlbl_sidlookup_cached - Cache a SID lookup
* @skb: the packet
* @secattr: the NetLabel security attributes
* @sid: the SID
*
* Description:
* Query the SELinux security server to lookup the correct SID for the given
* security attributes. If the query is successful, cache the result to speed
* up future lookups. Returns zero on success, negative values on failure.
*
*/
static int selinux_netlbl_sidlookup_cached(struct sk_buff *skb,
struct netlbl_lsm_secattr *secattr,
u32 *sid)
{
int rc;
rc = security_netlbl_secattr_to_sid(secattr, sid);
if (rc == 0 &&
(secattr->flags & NETLBL_SECATTR_CACHEABLE) &&
(secattr->flags & NETLBL_SECATTR_CACHE))
netlbl_cache_add(skb, secattr);
return rc;
}
/**
* selinux_netlbl_sock_genattr - Generate the NetLabel socket secattr
* @sk: the socket
*
* Description:
* Generate the NetLabel security attributes for a socket, making full use of
* the socket's attribute cache. Returns a pointer to the security attributes
* on success, NULL on failure.
*
*/
static struct netlbl_lsm_secattr *selinux_netlbl_sock_genattr(struct sock *sk)
{
int rc;
struct sk_security_struct *sksec = sk->sk_security;
struct netlbl_lsm_secattr *secattr;
if (sksec->nlbl_secattr != NULL)
return sksec->nlbl_secattr;
secattr = netlbl_secattr_alloc(GFP_ATOMIC);
if (secattr == NULL)
return NULL;
rc = security_netlbl_sid_to_secattr(sksec->sid, secattr);
if (rc != 0) {
netlbl_secattr_free(secattr);
return NULL;
}
sksec->nlbl_secattr = secattr;
return secattr;
}
/**
* selinux_netlbl_sock_setsid - Label a socket using the NetLabel mechanism
* @sk: the socket to label
*
* Description:
* Attempt to label a socket using the NetLabel mechanism. Returns zero values
* on success, negative values on failure.
*
*/
static int selinux_netlbl_sock_setsid(struct sock *sk)
{
int rc;
struct sk_security_struct *sksec = sk->sk_security;
struct netlbl_lsm_secattr *secattr;
if (sksec->nlbl_state != NLBL_REQUIRE)
return 0;
secattr = selinux_netlbl_sock_genattr(sk);
if (secattr == NULL)
return -ENOMEM;
rc = netlbl_sock_setattr(sk, secattr);
switch (rc) {
case 0:
sksec->nlbl_state = NLBL_LABELED;
break;
case -EDESTADDRREQ:
sksec->nlbl_state = NLBL_REQSKB;
rc = 0;
break;
}
return rc;
}
/**
* selinux_netlbl_cache_invalidate - Invalidate the NetLabel cache
*
* Description:
* Invalidate the NetLabel security attribute mapping cache.
*
*/
void selinux_netlbl_cache_invalidate(void)
{
netlbl_cache_invalidate();
}
/**
* selinux_netlbl_err - Handle a NetLabel packet error
* @skb: the packet
* @error: the error code
* @gateway: true if host is acting as a gateway, false otherwise
*
* Description:
* When a packet is dropped due to a call to avc_has_perm() pass the error
* code to the NetLabel subsystem so any protocol specific processing can be
* done. This is safe to call even if you are unsure if NetLabel labeling is
* present on the packet, NetLabel is smart enough to only act when it should.
*
*/
void selinux_netlbl_err(struct sk_buff *skb, int error, int gateway)
{
netlbl_skbuff_err(skb, error, gateway);
}
/**
* selinux_netlbl_sk_security_free - Free the NetLabel fields
* @sssec: the sk_security_struct
*
* Description:
* Free all of the memory in the NetLabel fields of a sk_security_struct.
*
*/
void selinux_netlbl_sk_security_free(struct sk_security_struct *ssec)
{
if (ssec->nlbl_secattr != NULL)
netlbl_secattr_free(ssec->nlbl_secattr);
}
/**
* selinux_netlbl_sk_security_reset - Reset the NetLabel fields
* @ssec: the sk_security_struct
* @family: the socket family
*
* Description:
* Called when the NetLabel state of a sk_security_struct needs to be reset.
* The caller is responsibile for all the NetLabel sk_security_struct locking.
*
*/
void selinux_netlbl_sk_security_reset(struct sk_security_struct *ssec,
int family)
{
if (family == PF_INET)
ssec->nlbl_state = NLBL_REQUIRE;
else
ssec->nlbl_state = NLBL_UNSET;
}
/**
* selinux_netlbl_skbuff_getsid - Get the sid of a packet using NetLabel
* @skb: the packet
* @family: protocol family
* @type: NetLabel labeling protocol type
* @sid: the SID
*
* Description:
* Call the NetLabel mechanism to get the security attributes of the given
* packet and use those attributes to determine the correct context/SID to
* assign to the packet. Returns zero on success, negative values on failure.
*
*/
int selinux_netlbl_skbuff_getsid(struct sk_buff *skb,
u16 family,
u32 *type,
u32 *sid)
{
int rc;
struct netlbl_lsm_secattr secattr;
if (!netlbl_enabled()) {
*sid = SECSID_NULL;
return 0;
}
netlbl_secattr_init(&secattr);
rc = netlbl_skbuff_getattr(skb, family, &secattr);
if (rc == 0 && secattr.flags != NETLBL_SECATTR_NONE)
rc = selinux_netlbl_sidlookup_cached(skb, &secattr, sid);
else
*sid = SECSID_NULL;
*type = secattr.type;
netlbl_secattr_destroy(&secattr);
return rc;
}
/**
* selinux_netlbl_skbuff_setsid - Set the NetLabel on a packet given a sid
* @skb: the packet
* @family: protocol family
* @sid: the SID
*
* Description
* Call the NetLabel mechanism to set the label of a packet using @sid.
* Returns zero on auccess, negative values on failure.
*
*/
int selinux_netlbl_skbuff_setsid(struct sk_buff *skb,
u16 family,
u32 sid)
{
int rc;
struct netlbl_lsm_secattr secattr_storage;
struct netlbl_lsm_secattr *secattr = NULL;
struct sock *sk;
/* if this is a locally generated packet check to see if it is already
* being labeled by it's parent socket, if it is just exit */
sk = skb->sk;
if (sk != NULL) {
struct sk_security_struct *sksec = sk->sk_security;
if (sksec->nlbl_state != NLBL_REQSKB)
return 0;
secattr = sksec->nlbl_secattr;
}
if (secattr == NULL) {
secattr = &secattr_storage;
netlbl_secattr_init(secattr);
rc = security_netlbl_sid_to_secattr(sid, secattr);
if (rc != 0)
goto skbuff_setsid_return;
}
rc = netlbl_skbuff_setattr(skb, family, secattr);
skbuff_setsid_return:
if (secattr == &secattr_storage)
netlbl_secattr_destroy(secattr);
return rc;
}
/**
* selinux_netlbl_inet_conn_established - Netlabel the newly accepted connection
* @sk: the new connection
*
* Description:
* A new connection has been established on @sk so make sure it is labeled
* correctly with the NetLabel susbsystem.
*
*/
void selinux_netlbl_inet_conn_established(struct sock *sk, u16 family)
{
int rc;
struct sk_security_struct *sksec = sk->sk_security;
struct netlbl_lsm_secattr *secattr;
struct inet_sock *sk_inet = inet_sk(sk);
struct sockaddr_in addr;
if (sksec->nlbl_state != NLBL_REQUIRE)
return;
secattr = selinux_netlbl_sock_genattr(sk);
if (secattr == NULL)
return;
rc = netlbl_sock_setattr(sk, secattr);
switch (rc) {
case 0:
sksec->nlbl_state = NLBL_LABELED;
break;
case -EDESTADDRREQ:
/* no PF_INET6 support yet because we don't support any IPv6
* labeling protocols */
if (family != PF_INET) {
sksec->nlbl_state = NLBL_UNSET;
return;
}
addr.sin_family = family;
addr.sin_addr.s_addr = sk_inet->daddr;
if (netlbl_conn_setattr(sk, (struct sockaddr *)&addr,
secattr) != 0) {
/* we failed to label the connected socket (could be
* for a variety of reasons, the actual "why" isn't
* important here) so we have to go to our backup plan,
* labeling the packets individually in the netfilter
* local output hook. this is okay but we need to
* adjust the MSS of the connection to take into
* account any labeling overhead, since we don't know
* the exact overhead at this point we'll use the worst
* case value which is 40 bytes for IPv4 */
struct inet_connection_sock *sk_conn = inet_csk(sk);
sk_conn->icsk_ext_hdr_len += 40 -
(sk_inet->opt ? sk_inet->opt->optlen : 0);
sk_conn->icsk_sync_mss(sk, sk_conn->icsk_pmtu_cookie);
sksec->nlbl_state = NLBL_REQSKB;
} else
sksec->nlbl_state = NLBL_CONNLABELED;
break;
default:
/* note that we are failing to label the socket which could be
* a bad thing since it means traffic could leave the system
* without the desired labeling, however, all is not lost as
* we have a check in selinux_netlbl_inode_permission() to
* pick up the pieces that we might drop here because we can't
* return an error code */
break;
}
}
/**
* selinux_netlbl_socket_post_create - Label a socket using NetLabel
* @sock: the socket to label
*
* Description:
* Attempt to label a socket using the NetLabel mechanism using the given
* SID. Returns zero values on success, negative values on failure.
*
*/
int selinux_netlbl_socket_post_create(struct socket *sock)
{
return selinux_netlbl_sock_setsid(sock->sk);
}
/**
* selinux_netlbl_inode_permission - Verify the socket is NetLabel labeled
* @inode: the file descriptor's inode
* @mask: the permission mask
*
* Description:
* Looks at a file's inode and if it is marked as a socket protected by
* NetLabel then verify that the socket has been labeled, if not try to label
* the socket now with the inode's SID. Returns zero on success, negative
* values on failure.
*
*/
int selinux_netlbl_inode_permission(struct inode *inode, int mask)
{
int rc;
struct sock *sk;
struct socket *sock;
struct sk_security_struct *sksec;
if (!S_ISSOCK(inode->i_mode) ||
((mask & (MAY_WRITE | MAY_APPEND)) == 0))
return 0;
sock = SOCKET_I(inode);
sk = sock->sk;
sksec = sk->sk_security;
if (sksec->nlbl_state != NLBL_REQUIRE)
return 0;
local_bh_disable();
bh_lock_sock_nested(sk);
if (likely(sksec->nlbl_state == NLBL_REQUIRE))
rc = selinux_netlbl_sock_setsid(sk);
else
rc = 0;
bh_unlock_sock(sk);
local_bh_enable();
return rc;
}
/**
* selinux_netlbl_sock_rcv_skb - Do an inbound access check using NetLabel
* @sksec: the sock's sk_security_struct
* @skb: the packet
* @family: protocol family
* @ad: the audit data
*
* Description:
* Fetch the NetLabel security attributes from @skb and perform an access check
* against the receiving socket. Returns zero on success, negative values on
* error.
*
*/
int selinux_netlbl_sock_rcv_skb(struct sk_security_struct *sksec,
struct sk_buff *skb,
u16 family,
struct avc_audit_data *ad)
{
int rc;
u32 nlbl_sid;
u32 perm;
struct netlbl_lsm_secattr secattr;
if (!netlbl_enabled())
return 0;
netlbl_secattr_init(&secattr);
rc = netlbl_skbuff_getattr(skb, family, &secattr);
if (rc == 0 && secattr.flags != NETLBL_SECATTR_NONE)
rc = selinux_netlbl_sidlookup_cached(skb, &secattr, &nlbl_sid);
else
nlbl_sid = SECINITSID_UNLABELED;
netlbl_secattr_destroy(&secattr);
if (rc != 0)
return rc;
switch (sksec->sclass) {
case SECCLASS_UDP_SOCKET:
perm = UDP_SOCKET__RECVFROM;
break;
case SECCLASS_TCP_SOCKET:
perm = TCP_SOCKET__RECVFROM;
break;
default:
perm = RAWIP_SOCKET__RECVFROM;
}
rc = avc_has_perm(sksec->sid, nlbl_sid, sksec->sclass, perm, ad);
if (rc == 0)
return 0;
if (nlbl_sid != SECINITSID_UNLABELED)
netlbl_skbuff_err(skb, rc, 0);
return rc;
}
/**
* selinux_netlbl_socket_setsockopt - Do not allow users to remove a NetLabel
* @sock: the socket
* @level: the socket level or protocol
* @optname: the socket option name
*
* Description:
* Check the setsockopt() call and if the user is trying to replace the IP
* options on a socket and a NetLabel is in place for the socket deny the
* access; otherwise allow the access. Returns zero when the access is
* allowed, -EACCES when denied, and other negative values on error.
*
*/
int selinux_netlbl_socket_setsockopt(struct socket *sock,
int level,
int optname)
{
int rc = 0;
struct sock *sk = sock->sk;
struct sk_security_struct *sksec = sk->sk_security;
struct netlbl_lsm_secattr secattr;
if (level == IPPROTO_IP && optname == IP_OPTIONS &&
(sksec->nlbl_state == NLBL_LABELED ||
sksec->nlbl_state == NLBL_CONNLABELED)) {
netlbl_secattr_init(&secattr);
lock_sock(sk);
rc = netlbl_sock_getattr(sk, &secattr);
release_sock(sk);
if (rc == 0)
rc = -EACCES;
else if (rc == -ENOMSG)
rc = 0;
netlbl_secattr_destroy(&secattr);
}
return rc;
}
/**
* selinux_netlbl_socket_connect - Label a client-side socket on connect
* @sk: the socket to label
* @addr: the destination address
*
* Description:
* Attempt to label a connected socket with NetLabel using the given address.
* Returns zero values on success, negative values on failure.
*
*/
int selinux_netlbl_socket_connect(struct sock *sk, struct sockaddr *addr)
{
int rc;
struct sk_security_struct *sksec = sk->sk_security;
struct netlbl_lsm_secattr *secattr;
if (sksec->nlbl_state != NLBL_REQSKB &&
sksec->nlbl_state != NLBL_CONNLABELED)
return 0;
local_bh_disable();
bh_lock_sock_nested(sk);
/* connected sockets are allowed to disconnect when the address family
* is set to AF_UNSPEC, if that is what is happening we want to reset
* the socket */
if (addr->sa_family == AF_UNSPEC) {
netlbl_sock_delattr(sk);
sksec->nlbl_state = NLBL_REQSKB;
rc = 0;
goto socket_connect_return;
}
secattr = selinux_netlbl_sock_genattr(sk);
if (secattr == NULL) {
rc = -ENOMEM;
goto socket_connect_return;
}
rc = netlbl_conn_setattr(sk, addr, secattr);
if (rc == 0)
sksec->nlbl_state = NLBL_CONNLABELED;
socket_connect_return:
bh_unlock_sock(sk);
local_bh_enable();
return rc;
}
