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.

Signed-off-by: Venkat Yekkirala <[EMAIL PROTECTED]>
---
dummy.c    |    7 ++
hooks.c    |   30 ++++++++--
security.h |   16 +++++
3 files changed, 49 insertions(+), 4 deletions(-)

--- linux-2.6.17.child_sock/include/linux/security.h    2006-07-31 
10:03:26.000000000 -0500
+++ linux-2.6.17/include/linux/security.h       2006-08-01 10:57:15.000000000 
-0500
@@ -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)
{
}
--- linux-2.6.17.child_sock/security/dummy.c    2006-07-31 10:03:26.000000000 
-0500
+++ linux-2.6.17/security/dummy.c       2006-08-01 10:57:37.000000000 -0500
@@ -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);
--- linux-2.6.17.child_sock/security/selinux/hooks.c    2006-07-31 
10:04:31.000000000 -0500
+++ linux-2.6.17/security/selinux/hooks.c       2006-08-01 10:33:43.000000000 
-0500
@@ -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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