Smack: bidirectional UDS connect check

Smack IPC policy requires that the sender have write access
to the receiver. UDS streams don't do per-packet checks. The
only check is done at connect time. The existing code checks
if the connecting process can write to the other, but not the
other way around. This change adds a check that the other end
can write to the connecting process.

Targeted for git://git.gitorious.org/smack-next/kernel.git

Signed-off-by: Casey Schuafler <casey@schaufler-ca.com>
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 3d1c908..3410e3a 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -1095,7 +1095,7 @@
 	ssp = sock->sk->sk_security;
 
 	if (strcmp(name, XATTR_SMACK_IPIN) == 0)
-		isp = ssp->smk_in;
+		isp = ssp->smk_in->smk_known;
 	else if (strcmp(name, XATTR_SMACK_IPOUT) == 0)
 		isp = ssp->smk_out->smk_known;
 	else
@@ -1859,7 +1859,7 @@
 	if (ssp == NULL)
 		return -ENOMEM;
 
-	ssp->smk_in = skp->smk_known;
+	ssp->smk_in = skp;
 	ssp->smk_out = skp;
 	ssp->smk_packet = NULL;
 
@@ -2099,7 +2099,7 @@
 
 	if (act == SMK_RECEIVING) {
 		skp = smack_net_ambient;
-		object = ssp->smk_in;
+		object = ssp->smk_in->smk_known;
 	} else {
 		skp = ssp->smk_out;
 		object = smack_net_ambient->smk_known;
@@ -2129,9 +2129,9 @@
 	list_for_each_entry(spp, &smk_ipv6_port_list, list) {
 		if (spp->smk_port != port)
 			continue;
-		object = spp->smk_in;
+		object = spp->smk_in->smk_known;
 		if (act == SMK_CONNECTING)
-			ssp->smk_packet = spp->smk_out->smk_known;
+			ssp->smk_packet = spp->smk_out;
 		break;
 	}
 
@@ -2195,7 +2195,7 @@
 	ssp = sock->sk->sk_security;
 
 	if (strcmp(name, XATTR_SMACK_IPIN) == 0)
-		ssp->smk_in = skp->smk_known;
+		ssp->smk_in = skp;
 	else if (strcmp(name, XATTR_SMACK_IPOUT) == 0) {
 		ssp->smk_out = skp;
 		if (sock->sk->sk_family == PF_INET) {
@@ -3054,30 +3054,34 @@
 				     struct sock *other, struct sock *newsk)
 {
 	struct smack_known *skp;
+	struct smack_known *okp;
 	struct socket_smack *ssp = sock->sk_security;
 	struct socket_smack *osp = other->sk_security;
 	struct socket_smack *nsp = newsk->sk_security;
 	struct smk_audit_info ad;
 	int rc = 0;
-
 #ifdef CONFIG_AUDIT
 	struct lsm_network_audit net;
-
-	smk_ad_init_net(&ad, __func__, LSM_AUDIT_DATA_NET, &net);
-	smk_ad_setfield_u_net_sk(&ad, other);
 #endif
 
 	if (!smack_privileged(CAP_MAC_OVERRIDE)) {
 		skp = ssp->smk_out;
-		rc = smk_access(skp, osp->smk_in, MAY_WRITE, &ad);
+		okp = osp->smk_out;
+#ifdef CONFIG_AUDIT
+		smk_ad_init_net(&ad, __func__, LSM_AUDIT_DATA_NET, &net);
+		smk_ad_setfield_u_net_sk(&ad, other);
+#endif
+		rc = smk_access(skp, okp->smk_known, MAY_WRITE, &ad);
+		if (rc == 0)
+			rc = smk_access(okp, okp->smk_known, MAY_WRITE, NULL);
 	}
 
 	/*
 	 * Cross reference the peer labels for SO_PEERSEC.
 	 */
 	if (rc == 0) {
-		nsp->smk_packet = ssp->smk_out->smk_known;
-		ssp->smk_packet = osp->smk_out->smk_known;
+		nsp->smk_packet = ssp->smk_out;
+		ssp->smk_packet = osp->smk_out;
 	}
 
 	return rc;
@@ -3109,7 +3113,7 @@
 		return 0;
 
 	skp = ssp->smk_out;
-	return smk_access(skp, osp->smk_in, MAY_WRITE, &ad);
+	return smk_access(skp, osp->smk_in->smk_known, MAY_WRITE, &ad);
 }
 
 /**
@@ -3204,7 +3208,7 @@
 		if (found)
 			return skp;
 
-		if (ssp != NULL && ssp->smk_in == smack_known_star.smk_known)
+		if (ssp != NULL && ssp->smk_in == &smack_known_star)
 			return &smack_known_web;
 		return &smack_known_star;
 	}
@@ -3323,7 +3327,7 @@
 		 * This is the simplist possible security model
 		 * for networking.
 		 */
-		rc = smk_access(skp, ssp->smk_in, MAY_WRITE, &ad);
+		rc = smk_access(skp, ssp->smk_in->smk_known, MAY_WRITE, &ad);
 		if (rc != 0)
 			netlbl_skbuff_err(skb, rc, 0);
 		break;
@@ -3358,7 +3362,7 @@
 
 	ssp = sock->sk->sk_security;
 	if (ssp->smk_packet != NULL) {
-		rcp = ssp->smk_packet;
+		rcp = ssp->smk_packet->smk_known;
 		slen = strlen(rcp) + 1;
 	}
 
@@ -3443,7 +3447,7 @@
 		return;
 
 	ssp = sk->sk_security;
-	ssp->smk_in = skp->smk_known;
+	ssp->smk_in = skp;
 	ssp->smk_out = skp;
 	/* cssp->smk_packet is already set in smack_inet_csk_clone() */
 }
@@ -3503,7 +3507,7 @@
 	 * Receiving a packet requires that the other end be able to write
 	 * here. Read access is not required.
 	 */
-	rc = smk_access(skp, ssp->smk_in, MAY_WRITE, &ad);
+	rc = smk_access(skp, ssp->smk_in->smk_known, MAY_WRITE, &ad);
 	if (rc != 0)
 		return rc;
 
@@ -3547,7 +3551,7 @@
 
 	if (req->peer_secid != 0) {
 		skp = smack_from_secid(req->peer_secid);
-		ssp->smk_packet = skp->smk_known;
+		ssp->smk_packet = skp;
 	} else
 		ssp->smk_packet = NULL;
 }