linux/security/selinux/netlabel.c
Paul Moore 6c5b3fc014 selinux: Cache NetLabel secattrs in the socket's security struct
Previous work enabled the use of address based NetLabel selectors, which
while highly useful, brought the potential for additional per-packet overhead
when used.  This patch attempts to mitigate some of that overhead by caching
the NetLabel security attribute struct within the SELinux socket security
structure.  This should help eliminate the need to recreate the NetLabel
secattr structure for each packet resulting in less overhead.

Signed-off-by: Paul Moore <paul.moore@hp.com>
Acked-by: James Morris <jmorris@namei.org>
2008-10-10 10:16:33 -04:00

546 lines
14 KiB
C

/*
* 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 && secattr.flags != NETLBL_SECATTR_NONE)
rc = -EACCES;
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;
}