SELinux: Fix SA selection semantics

[safe/jmp/linux-2.6] / security / selinux / xfrm.c

diff --git a/security/selinux/xfrm.c b/security/selinux/xfrm.c
index 8fef742..9b77714 100644 (file)
--- a/security/selinux/xfrm.c
+++ b/security/selinux/xfrm.c
@@ -115,71 +115,40 @@ int selinux_xfrm_state_pol_flow_match(struct xfrm_state *x, struct xfrm_policy *
                        struct flowi *fl)
 {
        u32 state_sid;
-       u32 pol_sid;
-       int err;
+       int rc;
 
-       if (xp->security) {
-               if (!x->security)
-                       /* unlabeled SA and labeled policy can't match */
-                       return 0;
-               else
-                       state_sid = x->security->ctx_sid;
-               pol_sid = xp->security->ctx_sid;
-       } else
+       if (!xp->security)
                if (x->security)
                        /* unlabeled policy and labeled SA can't match */
                        return 0;
                else
                        /* unlabeled policy and unlabeled SA match all flows */
                        return 1;
-
-       err = avc_has_perm(state_sid, pol_sid, SECCLASS_ASSOCIATION,
-                         ASSOCIATION__POLMATCH,
-                         NULL);
-
-       if (err)
-               return 0;
-
-       err = avc_has_perm(fl->secid, state_sid, SECCLASS_ASSOCIATION,
-                         ASSOCIATION__SENDTO,
-                         NULL)? 0:1;
-
-       return err;
-}
-
-/*
- * LSM hook implementation that authorizes that a particular outgoing flow
- * can use a given security association.
- */
-
-int selinux_xfrm_flow_state_match(struct flowi *fl, struct xfrm_state *xfrm,
-                                 struct xfrm_policy *xp)
-{
-       int rc = 0;
-       u32 sel_sid = SECINITSID_UNLABELED;
-       struct xfrm_sec_ctx *ctx;
-
-       if (!xp->security)
-               if (!xfrm->security)
-                       return 1;
-               else
-                       return 0;
        else
-               if (!xfrm->security)
+               if (!x->security)
+                       /* unlabeled SA and labeled policy can't match */
                        return 0;
+               else
+                       if (!selinux_authorizable_xfrm(x))
+                               /* Not a SELinux-labeled SA */
+                               return 0;
 
-       /* Context sid is either set to label or ANY_ASSOC */
-       if ((ctx = xfrm->security)) {
-               if (!selinux_authorizable_ctx(ctx))
-                       return 0;
+       state_sid = x->security->ctx_sid;
 
-               sel_sid = ctx->ctx_sid;
-       }
+       if (fl->secid != state_sid)
+               return 0;
 
-       rc = avc_has_perm(fl->secid, sel_sid, SECCLASS_ASSOCIATION,
+       rc = avc_has_perm(fl->secid, state_sid, SECCLASS_ASSOCIATION,
                          ASSOCIATION__SENDTO,
                          NULL)? 0:1;
 
+       /*
+        * We don't need a separate SA Vs. policy polmatch check
+        * since the SA is now of the same label as the flow and
+        * a flow Vs. policy polmatch check had already happened
+        * in selinux_xfrm_policy_lookup() above.
+        */
+
        return rc;
 }
 
@@ -481,6 +450,13 @@ int selinux_xfrm_sock_rcv_skb(u32 isec_sid, struct sk_buff *skb,
                }
        }
 
+       /*
+        * This check even when there's no association involved is
+        * intended, according to Trent Jaeger, to make sure a
+        * process can't engage in non-ipsec communication unless
+        * explicitly allowed by policy.
+        */
+
        rc = avc_has_perm(isec_sid, sel_sid, SECCLASS_ASSOCIATION,
                          ASSOCIATION__RECVFROM, ad);
 
@@ -492,10 +468,10 @@ int selinux_xfrm_sock_rcv_skb(u32 isec_sid, struct sk_buff *skb,
  * If we have no security association, then we need to determine
  * whether the socket is allowed to send to an unlabelled destination.
  * If we do have a authorizable security association, then it has already been
- * checked in xfrm_policy_lookup hook.
+ * checked in the selinux_xfrm_state_pol_flow_match hook above.
  */
 int selinux_xfrm_postroute_last(u32 isec_sid, struct sk_buff *skb,
-                                       struct avc_audit_data *ad)
+                                       struct avc_audit_data *ad, u8 proto)
 {
        struct dst_entry *dst;
        int rc = 0;
@@ -514,6 +490,27 @@ int selinux_xfrm_postroute_last(u32 isec_sid, struct sk_buff *skb,
                }
        }
 
+       switch (proto) {
+       case IPPROTO_AH:
+       case IPPROTO_ESP:
+       case IPPROTO_COMP:
+               /*
+                * We should have already seen this packet once before
+                * it underwent xfrm(s). No need to subject it to the
+                * unlabeled check.
+                */
+               goto out;
+       default:
+               break;
+       }
+
+       /*
+        * This check even when there's no association involved is
+        * intended, according to Trent Jaeger, to make sure a
+        * process can't engage in non-ipsec communication unless
+        * explicitly allowed by policy.
+        */
+
        rc = avc_has_perm(isec_sid, SECINITSID_UNLABELED, SECCLASS_ASSOCIATION,
                          ASSOCIATION__SENDTO, ad);
 out: