secid reconciliation-v01: add LSM hooks

Add skb_policy_check hook to LSM to enable reconciliation of the various security identifiers as well as enforce flow control on inbound (INPUT/FORWARD) traffic.

Also defines reconciliation for SELinux.

---

include/linux/security.h       |   16 ++++++++
security/dummy.c               |    7 +++
security/selinux/hooks.c       |   60 +++++++++++++++++++++++++------
security/selinux/ss/mls.c      |    2 +
security/selinux/ss/services.c |    2 +
5 files changed, 76 insertions(+), 11 deletions(-)

@@ -828,6 +828,9 @@ struct request_sock;
 *	Sets the new child socket's sid to the openreq sid.
 * @req_classify_flow:
 *	Sets the flow's sid to the openreq sid.
+ * @skb_policy_check:
+ *	Checks to see if security policy would allow skb into the system.
+ *	Returns 1 if skb allowed into system, 0 otherwise.
 *
 * Security hooks for XFRM operations.
 *

@@ -1372,6 +1375,7 @@ struct security_operations {

					struct request_sock *req);
	void (*inet_csk_clone)(struct sock *newsk, const struct request_sock *req);
	void (*req_classify_flow)(const struct request_sock *req, struct flowi *fl);

+ int (*skb_policy_check)(struct sk_buff *skb, unsigned short family);
#endif /* CONFIG_SECURITY_NETWORK */

#ifdef CONFIG_SECURITY_NETWORK_XFRM
@@ -2946,6 +2950,12 @@ static inline void security_req_classify

	security_ops->req_classify_flow(req, fl);
}

+static inline int security_skb_policy_check(struct sk_buff *skb,
+ unsigned short family)
+{
+ return security_ops->skb_policy_check(skb, family);
+}
+
static inline void security_sock_graft(struct sock* sk, struct socket *parent)

{
	security_ops->sock_graft(sk, parent);

@@ -3097,6 +3107,12 @@ static inline void security_req_classify {
}

+static inline int security_skb_policy_check(struct sk_buff *skb,
+ unsigned short family)
+{
+ return 1;
+}
+
static inline void security_sock_graft(struct sock* sk, struct socket *parent) {
}

@@ -832,6 +832,12 @@ static inline void dummy_req_classify_fl

struct flowi *fl)
{
}
+
+static inline int dummy_skb_policy_check(struct sk_buff *skb,
+ unsigned short family)
+{
+ return 1;
+}
#endif /* CONFIG_SECURITY_NETWORK */

#ifdef CONFIG_SECURITY_NETWORK_XFRM
@@ -1108,6 +1114,7 @@ void security_fixup_ops (struct security

	set_to_dummy_if_null(ops, inet_conn_request);
	set_to_dummy_if_null(ops, inet_csk_clone);
	set_to_dummy_if_null(ops, req_classify_flow);
+	set_to_dummy_if_null(ops, skb_policy_check);
 #endif	/* CONFIG_SECURITY_NETWORK */
#ifdef  CONFIG_SECURITY_NETWORK_XFRM
	set_to_dummy_if_null(ops, xfrm_policy_alloc_security);

@@ -3447,8 +3447,12 @@ static int selinux_sock_rcv_skb_compat(s
 

		err = avc_has_perm(sock_sid, port_sid,
				   sock_class, recv_perm, ad);
+		if (err)
+			goto out;
	}

+ err = selinux_xfrm_sock_rcv_skb(sock_sid, skb, ad);
+
out:

	return err;
}
@@ -3487,10 +3491,6 @@ static int selinux_socket_sock_rcv_skb(s
		goto out;

	err = selinux_netlbl_sock_rcv_skb(sksec, skb, &ad);

- if (err)
- goto out;
-
- err = selinux_xfrm_sock_rcv_skb(sksec->sid, skb, &ad);
out:

	return err;
}
@@ -3622,13 +3622,16 @@ static int selinux_inet_conn_request(str
		return 0;
	}

- err = selinux_xfrm_decode_session(skb, &peersid, 0);
- BUG_ON(err);
-
- if (peersid == SECSID_NULL) {
- req->secid = sksec->sid;
- return 0;
- }
+ if (selinux_compat_net) {
+ err = selinux_xfrm_decode_session(skb, &peersid, 0);
+ BUG_ON(err);
+
+ if (peersid == SECSID_NULL) {
+ req->secid = sksec->sid;
+ return 0;
+ }
+ } else
+ peersid = skb->secmark;

	err = security_sid_mls_copy(sksec->sid, peersid, &newsid);
	if (err)
@@ -3656,6 +3659,40 @@ static void selinux_req_classify_flow(co
	fl->secid = req->secid;
}

+static int selinux_skb_policy_check(struct sk_buff *skb, unsigned short family) +{
+ u32 xfrm_sid, trans_sid;
+ int err;
+
+ if (selinux_compat_net)
+ return 1;
+
+ err = selinux_xfrm_decode_session(skb, &xfrm_sid, 0);
+ BUG_ON(err);
+
+ if (xfrm_sid) {
+ err = security_transition_sid(xfrm_sid, skb->secmark,
+ SECCLASS_PACKET, &trans_sid);
+ if (err)
+ goto out;
+ }
+ else
+ trans_sid = SECSID_NULL;
+
+ err = avc_has_perm(trans_sid, skb->secmark, SECCLASS_PACKET,
+ PACKET__FLOW_IN, NULL);
+ if (err)
+ goto out;
+
+ if (trans_sid != SECSID_NULL && trans_sid != SECINITSID_UNLABELED)
+ skb->secmark = trans_sid;
+
+ /* See if CIPSO can flow in thru the current secmark here */
+
+out:
+ return err ? 0 : 1;
+}
+
static int selinux_nlmsg_perm(struct sock *sk, struct sk_buff *skb)

{
	int err = 0;

@@ -4713,6 +4750,7 @@ static struct security_operations selinu
.inet_conn_request = selinux_inet_conn_request,
.inet_csk_clone = selinux_inet_csk_clone,
.req_classify_flow = selinux_req_classify_flow,
+ .skb_policy_check = selinux_skb_policy_check,

#ifdef CONFIG_SECURITY_NETWORK_XFRM
.xfrm_policy_alloc_security = selinux_xfrm_policy_alloc,

@@ -548,6 +548,8 @@ int mls_compute_sid(struct context *scon

				}
			}
		}
+		else if (tclass == SECCLASS_PACKET)
+			return mls_copy_context(newcontext, scontext);
		/* Fallthrough */
	case AVTAB_CHANGE:
		if (tclass == SECCLASS_PROCESS)

@@ -832,6 +832,7 @@ static int security_compute_sid(u32 ssid
 

	if (!ss_initialized) {
		switch (tclass) {
+		case SECCLASS_PACKET:
		case SECCLASS_PROCESS:
			*out_sid = ssid;
			break;

@@ -876,6 +877,7 @@ static int security_compute_sid(u32 ssid

	/* Set the role and type to default values. */
	switch (tclass) {
+	case SECCLASS_PACKET:
	case SECCLASS_PROCESS:
		/* Use the current role and type of process. */
		newcontext.role = scontext->role;

--
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