selinux: Set socket NetLabel based on connection endpoint
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 solve that by applying NetLabel socket labels
when sockets are connect()'d. This should alleviate the per-packet NetLabel
labeling for all connected sockets (yes, it even works for connected DGRAM
sockets).
Signed-off-by: Paul Moore <paul.moore@hp.com>
Reviewed-by: James Morris <jmorris@namei.org>
diff --git a/security/selinux/netlabel.c b/security/selinux/netlabel.c
index 090404d..b22b7da 100644
--- a/security/selinux/netlabel.c
+++ b/security/selinux/netlabel.c
@@ -29,10 +29,12 @@
#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/inet_sock.h>
-#include <net/inet_connection_sock.h>
+#include <net/ip.h>
+#include <net/ipv6.h>
#include "objsec.h"
#include "security.h"
@@ -79,8 +81,6 @@
int rc;
struct sk_security_struct *sksec = sk->sk_security;
struct netlbl_lsm_secattr secattr;
- struct inet_sock *sk_inet;
- struct inet_connection_sock *sk_conn;
if (sksec->nlbl_state != NLBL_REQUIRE)
return 0;
@@ -96,20 +96,6 @@
sksec->nlbl_state = NLBL_LABELED;
break;
case -EDESTADDRREQ:
- /* we are going to possibly end up labeling the individual
- * packets later which is problematic for stream sockets
- * because of the additional IP header size, our solution is to
- * allow for the maximum IP header length (40 bytes for IPv4,
- * we don't have to worry about IPv6 yet) just in case */
- sk_inet = inet_sk(sk);
- if (sk_inet->is_icsk) {
- sk_conn = inet_csk(sk);
- if (sk_inet->opt)
- sk_conn->icsk_ext_hdr_len -=
- sk_inet->opt->optlen;
- sk_conn->icsk_ext_hdr_len += 40;
- sk_conn->icsk_sync_mss(sk, sk_conn->icsk_pmtu_cookie);
- }
sksec->nlbl_state = NLBL_REQSKB;
rc = 0;
break;
@@ -247,21 +233,77 @@
}
/**
- * selinux_netlbl_sock_graft - Netlabel the new socket
+ * selinux_netlbl_inet_conn_established - Netlabel the newly accepted connection
* @sk: the new connection
- * @sock: the new socket
*
* Description:
- * The connection represented by @sk is being grafted onto @sock so set the
- * socket's NetLabel to match the SID of @sk.
+ * A new connection has been established on @sk so make sure it is labeled
+ * correctly with the NetLabel susbsystem.
*
*/
-void selinux_netlbl_sock_graft(struct sock *sk, struct socket *sock)
+void selinux_netlbl_inet_conn_established(struct sock *sk, u16 family)
{
- /* Try to set the NetLabel on the socket to save time later, if we fail
- * here we will pick up the pieces in later calls to
- * selinux_netlbl_inode_permission(). */
- selinux_netlbl_sock_setsid(sk);
+ 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;
+
+ netlbl_secattr_init(&secattr);
+ if (security_netlbl_sid_to_secattr(sksec->sid, &secattr) != 0)
+ goto inet_conn_established_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;
+ goto inet_conn_established_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;
+ }
+
+inet_conn_established_return:
+ netlbl_secattr_destroy(&secattr);
+ return;
}
/**
@@ -398,7 +440,8 @@
struct netlbl_lsm_secattr secattr;
if (level == IPPROTO_IP && optname == IP_OPTIONS &&
- sksec->nlbl_state == NLBL_LABELED) {
+ (sksec->nlbl_state == NLBL_LABELED ||
+ sksec->nlbl_state == NLBL_CONNLABELED)) {
netlbl_secattr_init(&secattr);
lock_sock(sk);
rc = netlbl_sock_getattr(sk, &secattr);
@@ -410,3 +453,51 @@
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;
+
+ netlbl_secattr_init(&secattr);
+ 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;
+ }
+ rc = security_netlbl_sid_to_secattr(sksec->sid, &secattr);
+ if (rc != 0)
+ goto socket_connect_return;
+ rc = netlbl_conn_setattr(sk, addr, &secattr);
+ if (rc != 0)
+ goto socket_connect_return;
+ sksec->nlbl_state = NLBL_CONNLABELED;
+
+socket_connect_return:
+ bh_unlock_sock(sk);
+ local_bh_enable();
+ netlbl_secattr_destroy(&secattr);
+ return rc;
+}
