[MLSXFRM]: Add security sid to sock

This adds security for IP sockets at the sock level. Security at the
sock level is needed to enforce the SELinux security policy for
security associations even when a sock is orphaned (such as in the TCP
LAST_ACK state).

This will also be used to enforce SELinux controls over data arriving
at or leaving a child socket while it's still waiting to be accepted.
Signed-off-by: Venkat Yekkirala <vyekkirala@TrustedCS.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/security.h

@@ -812,6 +812,8 @@ struct swap_info_struct;
  *      which is used to copy security attributes between local stream sockets.
  * @sk_free_security:
  *	Deallocate security structure.
+ * @sk_clone_security:
+ *	Clone/copy security structure.
  * @sk_getsid:
  *	Retrieve the LSM-specific sid for the sock to enable caching of network
  *	authorizations.
@@ -1332,6 +1334,7 @@ struct security_operations {
 	int (*socket_getpeersec_dgram) (struct socket *sock, struct sk_buff *skb, u32 *secid);
 	int (*sk_alloc_security) (struct sock *sk, int family, gfp_t priority);
 	void (*sk_free_security) (struct sock *sk);
+	void (*sk_clone_security) (const struct sock *sk, struct sock *newsk);
 	unsigned int (*sk_getsid) (struct sock *sk, struct flowi *fl, u8 dir);
 #endif	/* CONFIG_SECURITY_NETWORK */
 
@@ -2885,6 +2888,11 @@ static inline void security_sk_free(struct sock *sk)
 	return security_ops->sk_free_security(sk);
 }
 
+static inline void security_sk_clone(const struct sock *sk, struct sock *newsk)
+{
+	return security_ops->sk_clone_security(sk, newsk);
+}
+
 static inline unsigned int security_sk_sid(struct sock *sk, struct flowi *fl, u8 dir)
 {
 	return security_ops->sk_getsid(sk, fl, dir);
@@ -3011,6 +3019,10 @@ static inline void security_sk_free(struct sock *sk)
 {
 }
 
+static inline void security_sk_clone(const struct sock *sk, struct sock *newsk)
+{
+}
+
 static inline unsigned int security_sk_sid(struct sock *sk, struct flowi *fl, u8 dir)
 {
 	return 0;

include/net/sock.h

@@ -972,6 +972,19 @@ static inline void sock_graft(struct sock *sk, struct socket *parent)
 	write_unlock_bh(&sk->sk_callback_lock);
 }
 
+static inline void sock_copy(struct sock *nsk, const struct sock *osk)
+{
+#ifdef CONFIG_SECURITY_NETWORK
+	void *sptr = nsk->sk_security;
+#endif
+
+	memcpy(nsk, osk, osk->sk_prot->obj_size);
+#ifdef CONFIG_SECURITY_NETWORK
+	nsk->sk_security = sptr;
+	security_sk_clone(osk, nsk);
+#endif
+}
+
 extern int sock_i_uid(struct sock *sk);
 extern unsigned long sock_i_ino(struct sock *sk);
 

net/core/sock.c

@@ -911,7 +911,7 @@ struct sock *sk_clone(const struct sock *sk, const gfp_t priority)
 	if (newsk != NULL) {
 		struct sk_filter *filter;
 
-		memcpy(newsk, sk, sk->sk_prot->obj_size);
+		sock_copy(newsk, sk);
 
 		/* SANITY */
 		sk_node_init(&newsk->sk_node);

security/dummy.c

@@ -805,6 +805,10 @@ static inline void dummy_sk_free_security (struct sock *sk)
 {
 }
 
+static inline void dummy_sk_clone_security (const struct sock *sk, struct sock *newsk)
+{
+}
+
 static unsigned int dummy_sk_getsid(struct sock *sk, struct flowi *fl, u8 dir)
 {
 	return 0;
@@ -1060,6 +1064,7 @@ void security_fixup_ops (struct security_operations *ops)
 	set_to_dummy_if_null(ops, socket_getpeersec_dgram);
 	set_to_dummy_if_null(ops, sk_alloc_security);
 	set_to_dummy_if_null(ops, sk_free_security);
+	set_to_dummy_if_null(ops, sk_clone_security);
 	set_to_dummy_if_null(ops, sk_getsid);
  #endif	/* CONFIG_SECURITY_NETWORK */
 #ifdef  CONFIG_SECURITY_NETWORK_XFRM

security/selinux/hooks.c

@@ -269,15 +269,13 @@ static int sk_alloc_security(struct sock *sk, int family, gfp_t priority)
 {
 	struct sk_security_struct *ssec;
 
-	if (family != PF_UNIX)
-		return 0;
-
 	ssec = kzalloc(sizeof(*ssec), priority);
 	if (!ssec)
 		return -ENOMEM;
 
 	ssec->sk = sk;
 	ssec->peer_sid = SECINITSID_UNLABELED;
+	ssec->sid = SECINITSID_UNLABELED;
 	sk->sk_security = ssec;
 
 	return 0;
@@ -287,9 +285,6 @@ static void sk_free_security(struct sock *sk)
 {
 	struct sk_security_struct *ssec = sk->sk_security;
 
-	if (sk->sk_family != PF_UNIX)
-		return;
-
 	sk->sk_security = NULL;
 	kfree(ssec);
 }
@@ -3068,6 +3063,7 @@ static void selinux_socket_post_create(struct socket *sock, int family,
 {
 	struct inode_security_struct *isec;
 	struct task_security_struct *tsec;
+	struct sk_security_struct *sksec;
 	u32 newsid;
 
 	isec = SOCK_INODE(sock)->i_security;
@@ -3078,6 +3074,11 @@ static void selinux_socket_post_create(struct socket *sock, int family,
 	isec->sid = kern ? SECINITSID_KERNEL : newsid;
 	isec->initialized = 1;
 
+	if (sock->sk) {
+		sksec = sock->sk->sk_security;
+		sksec->sid = isec->sid;
+	}
+
 	return;
 }
 
@@ -3551,22 +3552,24 @@ static void selinux_sk_free_security(struct sock *sk)
 	sk_free_security(sk);
 }
 
-static unsigned int selinux_sk_getsid_security(struct sock *sk, struct flowi *fl, u8 dir)
+static void selinux_sk_clone_security(const struct sock *sk, struct sock *newsk)
 {
-	struct inode_security_struct *isec;
-	u32 sock_sid = SECINITSID_ANY_SOCKET;
+	struct sk_security_struct *ssec = sk->sk_security;
+	struct sk_security_struct *newssec = newsk->sk_security;
 
+	newssec->sid = ssec->sid;
+	newssec->peer_sid = ssec->peer_sid;
+}
+
+static unsigned int selinux_sk_getsid_security(struct sock *sk, struct flowi *fl, u8 dir)
+{
 	if (!sk)
 		return selinux_no_sk_sid(fl);
+	else {
+		struct sk_security_struct *sksec = sk->sk_security;
 
-	read_lock_bh(&sk->sk_callback_lock);
-	isec = get_sock_isec(sk);
-
-	if (isec)
-		sock_sid = isec->sid;
-
-	read_unlock_bh(&sk->sk_callback_lock);
-	return sock_sid;
+		return sksec->sid;
+	}
 }
 
 static int selinux_nlmsg_perm(struct sock *sk, struct sk_buff *skb)
@@ -4618,6 +4621,7 @@ static struct security_operations selinux_ops = {
 	.socket_getpeersec_dgram =	selinux_socket_getpeersec_dgram,
 	.sk_alloc_security =		selinux_sk_alloc_security,
 	.sk_free_security =		selinux_sk_free_security,
+	.sk_clone_security =		selinux_sk_clone_security,
 	.sk_getsid = 			selinux_sk_getsid_security,
 
 #ifdef CONFIG_SECURITY_NETWORK_XFRM

security/selinux/include/objsec.h

@@ -99,6 +99,7 @@ struct netif_security_struct {
 
 struct sk_security_struct {
 	struct sock *sk;		/* back pointer to sk object */
+	u32 sid;			/* SID of this object */
 	u32 peer_sid;			/* SID of peer */
 };