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/hooks.c b/security/selinux/hooks.c
index 7432bdd..632ac3e 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -3794,6 +3794,7 @@
static int selinux_socket_connect(struct socket *sock, struct sockaddr *address, int addrlen)
{
+ struct sock *sk = sock->sk;
struct inode_security_struct *isec;
int err;
@@ -3807,7 +3808,6 @@
isec = SOCK_INODE(sock)->i_security;
if (isec->sclass == SECCLASS_TCP_SOCKET ||
isec->sclass == SECCLASS_DCCP_SOCKET) {
- struct sock *sk = sock->sk;
struct avc_audit_data ad;
struct sockaddr_in *addr4 = NULL;
struct sockaddr_in6 *addr6 = NULL;
@@ -3841,6 +3841,8 @@
goto out;
}
+ err = selinux_netlbl_socket_connect(sk, address);
+
out:
return err;
}
@@ -4290,8 +4292,6 @@
sk->sk_family == PF_UNIX)
isec->sid = sksec->sid;
sksec->sclass = isec->sclass;
-
- selinux_netlbl_sock_graft(sk, parent);
}
static int selinux_inet_conn_request(struct sock *sk, struct sk_buff *skb,
@@ -4342,8 +4342,7 @@
selinux_netlbl_sk_security_reset(newsksec, req->rsk_ops->family);
}
-static void selinux_inet_conn_established(struct sock *sk,
- struct sk_buff *skb)
+static void selinux_inet_conn_established(struct sock *sk, struct sk_buff *skb)
{
u16 family = sk->sk_family;
struct sk_security_struct *sksec = sk->sk_security;
@@ -4353,6 +4352,8 @@
family = PF_INET;
selinux_skb_peerlbl_sid(skb, family, &sksec->peer_sid);
+
+ selinux_netlbl_inet_conn_established(sk, family);
}
static void selinux_req_classify_flow(const struct request_sock *req,
diff --git a/security/selinux/include/netlabel.h b/security/selinux/include/netlabel.h
index b3e6ae0..982bac0 100644
--- a/security/selinux/include/netlabel.h
+++ b/security/selinux/include/netlabel.h
@@ -52,7 +52,7 @@
u16 family,
u32 sid);
-void selinux_netlbl_sock_graft(struct sock *sk, struct socket *sock);
+void selinux_netlbl_inet_conn_established(struct sock *sk, u16 family);
int selinux_netlbl_socket_post_create(struct socket *sock);
int selinux_netlbl_inode_permission(struct inode *inode, int mask);
int selinux_netlbl_sock_rcv_skb(struct sk_security_struct *sksec,
@@ -62,6 +62,8 @@
int selinux_netlbl_socket_setsockopt(struct socket *sock,
int level,
int optname);
+int selinux_netlbl_socket_connect(struct sock *sk, struct sockaddr *addr);
+
#else
static inline void selinux_netlbl_cache_invalidate(void)
{
@@ -98,8 +100,14 @@
return 0;
}
-static inline void selinux_netlbl_sock_graft(struct sock *sk,
- struct socket *sock)
+static inline int selinux_netlbl_conn_setsid(struct sock *sk,
+ struct sockaddr *addr)
+{
+ return 0;
+}
+
+static inline void selinux_netlbl_inet_conn_established(struct sock *sk,
+ u16 family)
{
return;
}
@@ -125,6 +133,11 @@
{
return 0;
}
+static inline int selinux_netlbl_socket_connect(struct sock *sk,
+ struct sockaddr *addr)
+{
+ return 0;
+}
#endif /* CONFIG_NETLABEL */
#endif
diff --git a/security/selinux/include/objsec.h b/security/selinux/include/objsec.h
index f46dd1c..ad34787 100644
--- a/security/selinux/include/objsec.h
+++ b/security/selinux/include/objsec.h
@@ -118,6 +118,7 @@
NLBL_REQUIRE,
NLBL_LABELED,
NLBL_REQSKB,
+ NLBL_CONNLABELED,
} nlbl_state;
#endif
};
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;
+}