secid reconciliation on inbound: 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.

---

dummy.c    |    7 ++
hooks.c    |   30 ++++++++--
security.h |   16 +++++
3 files changed, 49 insertions(+), 4 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 is allowed, 0 otherwise.
 *
 * Security hooks for XFRM operations.
 *

@@ -1360,6 +1363,7 @@ 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
@@ -2917,6 +2921,12 @@ 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);

@@ -3068,6 +3078,12 @@ 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) {
}

@@ -833,6 +833,12 @@ 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
@@ -1098,6 +1104,7 @@ 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);

@@ -3465,11 +3465,11 @@ static int selinux_socket_sock_rcv_skb(s

	else
		err = avc_has_perm(sksec->sid, skb->secmark, SECCLASS_PACKET,
				   PACKET__RECV, &ad);

- if (err)
- goto out;
+ /* if (err) */
+ /* goto out; */

- err = selinux_xfrm_sock_rcv_skb(sksec->sid, skb, &ad);
-out:
+ /* err = selinux_xfrm_sock_rcv_skb(sksec->sid, skb, &ad); */
+out:

	return err;
}

@@ -3624,6 +3624,27 @@ void selinux_req_classify_flow(const str

	fl->secid = req->secid;
}

+static int selinux_skb_policy_check(struct sk_buff *skb, unsigned short family) +{
+ u32 xfrm_sid;
+ int err;
+
+ err = selinux_xfrm_decode_session(skb, &xfrm_sid, 0);
+ BUG_ON(err);
+
+ err = avc_has_perm(xfrm_sid, skb->secmark, SECCLASS_PACKET,
+ PACKET__COME_THRU, NULL);
+ if (err)
+ goto out;
+
+ skb->secmark = xfrm_sid;
+
+ /* See if CIPSO can COME_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;

@@ -4667,6 +4688,7 @@ 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,

--
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Did you mean to leave the call to selinux_xfrm_sock_rcv_skb() commented out?

- James

James Morris
<[email protected]>