[MLSXFRM]: Flow based matching of xfrm policy and state

This implements a seemless mechanism for xfrm policy selection and
state matching based on the flow sid. This also includes the necessary
SELinux enforcement pieces.

Signed-off-by: Venkat Yekkirala <vyekkirala@TrustedCS.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 25 insertions, 15 deletions

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 3da67ca..79405da 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -597,7 +597,7 @@ EXPORT_SYMBOL(xfrm_policy_walk);
 
 /* Find policy to apply to this flow. */
 
-static void xfrm_policy_lookup(struct flowi *fl, u32 sk_sid, u16 family, u8 dir,
+static void xfrm_policy_lookup(struct flowi *fl, u16 family, u8 dir,
 			       void **objp, atomic_t **obj_refp)
 {
 	struct xfrm_policy *pol;
@@ -613,7 +613,7 @@ static void xfrm_policy_lookup(struct flowi *fl, u32 sk_sid, u16 family, u8 dir,
 		match = xfrm_selector_match(sel, fl, family);
 
 		if (match) {
- 			if (!security_xfrm_policy_lookup(pol, sk_sid, dir)) {
+ 			if (!security_xfrm_policy_lookup(pol, fl->secid, dir)) {
 				xfrm_pol_hold(pol);
 				break;
 			}
@@ -641,7 +641,7 @@ static inline int policy_to_flow_dir(int dir)
 	};
 }
 
-static struct xfrm_policy *xfrm_sk_policy_lookup(struct sock *sk, int dir, struct flowi *fl, u32 sk_sid)
+static struct xfrm_policy *xfrm_sk_policy_lookup(struct sock *sk, int dir, struct flowi *fl)
 {
 	struct xfrm_policy *pol;
 
@@ -652,7 +652,7 @@ static struct xfrm_policy *xfrm_sk_policy_lookup(struct sock *sk, int dir, struc
  		int err = 0;
 
 		if (match)
-		  err = security_xfrm_policy_lookup(pol, sk_sid, policy_to_flow_dir(dir));
+		  err = security_xfrm_policy_lookup(pol, fl->secid, policy_to_flow_dir(dir));
 
  		if (match && !err)
 			xfrm_pol_hold(pol);
@@ -862,19 +862,20 @@ int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
 	u32 genid;
 	u16 family;
 	u8 dir = policy_to_flow_dir(XFRM_POLICY_OUT);
-	u32 sk_sid = security_sk_sid(sk, fl, dir);
+
+	fl->secid = security_sk_sid(sk, fl, dir);
 restart:
 	genid = atomic_read(&flow_cache_genid);
 	policy = NULL;
 	if (sk && sk->sk_policy[1])
-		policy = xfrm_sk_policy_lookup(sk, XFRM_POLICY_OUT, fl, sk_sid);
+		policy = xfrm_sk_policy_lookup(sk, XFRM_POLICY_OUT, fl);
 
 	if (!policy) {
 		/* To accelerate a bit...  */
 		if ((dst_orig->flags & DST_NOXFRM) || !xfrm_policy_list[XFRM_POLICY_OUT])
 			return 0;
 
-		policy = flow_cache_lookup(fl, sk_sid, dst_orig->ops->family,
+		policy = flow_cache_lookup(fl, dst_orig->ops->family,
 					   dir, xfrm_policy_lookup);
 	}
 
@@ -1032,13 +1033,15 @@ int
 xfrm_decode_session(struct sk_buff *skb, struct flowi *fl, unsigned short family)
 {
 	struct xfrm_policy_afinfo *afinfo = xfrm_policy_get_afinfo(family);
+	int err;
 
 	if (unlikely(afinfo == NULL))
 		return -EAFNOSUPPORT;
 
 	afinfo->decode_session(skb, fl);
+	err = security_xfrm_decode_session(skb, fl);
 	xfrm_policy_put_afinfo(afinfo);
-	return 0;
+	return err;
 }
 EXPORT_SYMBOL(xfrm_decode_session);
 
@@ -1058,14 +1061,11 @@ int __xfrm_policy_check(struct sock *sk, int dir, struct sk_buff *skb,
 	struct xfrm_policy *pol;
 	struct flowi fl;
 	u8 fl_dir = policy_to_flow_dir(dir);
-	u32 sk_sid;
 
 	if (xfrm_decode_session(skb, &fl, family) < 0)
 		return 0;
 	nf_nat_decode_session(skb, &fl, family);
 
-	sk_sid = security_sk_sid(sk, &fl, fl_dir);
-
 	/* First, check used SA against their selectors. */
 	if (skb->sp) {
 		int i;
@@ -1079,10 +1079,10 @@ int __xfrm_policy_check(struct sock *sk, int dir, struct sk_buff *skb,
 
 	pol = NULL;
 	if (sk && sk->sk_policy[dir])
-		pol = xfrm_sk_policy_lookup(sk, dir, &fl, sk_sid);
+		pol = xfrm_sk_policy_lookup(sk, dir, &fl);
 
 	if (!pol)
-		pol = flow_cache_lookup(&fl, sk_sid, family, fl_dir,
+		pol = flow_cache_lookup(&fl, family, fl_dir,
 					xfrm_policy_lookup);
 
 	if (!pol)
@@ -1298,6 +1298,8 @@ int xfrm_bundle_ok(struct xfrm_dst *first, struct flowi *fl, int family)
 
 		if (fl && !xfrm_selector_match(&dst->xfrm->sel, fl, family))
 			return 0;
+		if (fl && !security_xfrm_flow_state_match(fl, dst->xfrm))
+			return 0;
 		if (dst->xfrm->km.state != XFRM_STATE_VALID)
 			return 0;
 
diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c
index 0021aad..be02bd9 100644
--- a/net/xfrm/xfrm_state.c
+++ b/net/xfrm/xfrm_state.c
@@ -367,7 +367,7 @@ xfrm_state_find(xfrm_address_t *daddr, xfrm_address_t *saddr,
 			 */
 			if (x->km.state == XFRM_STATE_VALID) {
 				if (!xfrm_selector_match(&x->sel, fl, family) ||
-				    !xfrm_sec_ctx_match(pol->security, x->security))
+				    !security_xfrm_state_pol_flow_match(x, pol, fl))
 					continue;
 				if (!best ||
 				    best->km.dying > x->km.dying ||
@@ -379,7 +379,7 @@ xfrm_state_find(xfrm_address_t *daddr, xfrm_address_t *saddr,
 			} else if (x->km.state == XFRM_STATE_ERROR ||
 				   x->km.state == XFRM_STATE_EXPIRED) {
  				if (xfrm_selector_match(&x->sel, fl, family) &&
-				    xfrm_sec_ctx_match(pol->security, x->security))
+				    security_xfrm_state_pol_flow_match(x, pol, fl))
 					error = -ESRCH;
 			}
 		}
@@ -403,6 +403,14 @@ xfrm_state_find(xfrm_address_t *daddr, xfrm_address_t *saddr,
 		 * to current session. */
 		xfrm_init_tempsel(x, fl, tmpl, daddr, saddr, family);
 
+		error = security_xfrm_state_alloc_acquire(x, pol->security, fl->secid);
+		if (error) {
+			x->km.state = XFRM_STATE_DEAD;
+			xfrm_state_put(x);
+			x = NULL;
+			goto out;
+		}
+
 		if (km_query(x, tmpl, pol) == 0) {
 			x->km.state = XFRM_STATE_ACQ;
 			list_add_tail(&x->bydst, xfrm_state_bydst+h);