selinux: export validatetrans decisions

Make validatetrans decisions available through selinuxfs.
"/validatetrans" is added to selinuxfs for this purpose.
This functionality is needed by file system servers
implemented in userspace or kernelspace without the VFS
layer.

Writing "$oldcontext $newcontext $tclass $taskcontext"
to /validatetrans is expected to return 0 if the transition
is allowed and -EPERM otherwise.

Signed-off-by: Andrew Perepechko <anserper@ya.ru>
CC: andrew.perepechko@seagate.com
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <pmoore@redhat.com>

1 files changed, 27 insertions, 7 deletions

diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c
index ebb5eb3c318c..ebda97333f1b 100644
--- a/security/selinux/ss/services.c
+++ b/security/selinux/ss/services.c
@@ -778,8 +778,8 @@ out:
 	return -EPERM;
 }
 
-int security_validate_transition(u32 oldsid, u32 newsid, u32 tasksid,
-				 u16 orig_tclass)
+static int security_compute_validatetrans(u32 oldsid, u32 newsid, u32 tasksid,
+					  u16 orig_tclass, bool user)
 {
 	struct context *ocontext;
 	struct context *ncontext;
@@ -794,11 +794,12 @@ int security_validate_transition(u32 oldsid, u32 newsid, u32 tasksid,
 
 	read_lock(&policy_rwlock);
 
-	tclass = unmap_class(orig_tclass);
+	if (!user)
+		tclass = unmap_class(orig_tclass);
+	else
+		tclass = orig_tclass;
 
 	if (!tclass || tclass > policydb.p_classes.nprim) {
-		printk(KERN_ERR "SELinux: %s:  unrecognized class %d\n",
-			__func__, tclass);
 		rc = -EINVAL;
 		goto out;
 	}
@@ -832,8 +833,13 @@ int security_validate_transition(u32 oldsid, u32 newsid, u32 tasksid,
 	while (constraint) {
 		if (!constraint_expr_eval(ocontext, ncontext, tcontext,
 					  constraint->expr)) {
-			rc = security_validtrans_handle_fail(ocontext, ncontext,
-							     tcontext, tclass);
+			if (user)
+				rc = -EPERM;
+			else
+				rc = security_validtrans_handle_fail(ocontext,
+								     ncontext,
+								     tcontext,
+								     tclass);
 			goto out;
 		}
 		constraint = constraint->next;
@@ -844,6 +850,20 @@ out:
 	return rc;
 }
 
+int security_validate_transition_user(u32 oldsid, u32 newsid, u32 tasksid,
+					u16 tclass)
+{
+	return security_compute_validatetrans(oldsid, newsid, tasksid,
+						tclass, true);
+}
+
+int security_validate_transition(u32 oldsid, u32 newsid, u32 tasksid,
+				 u16 orig_tclass)
+{
+	return security_compute_validatetrans(oldsid, newsid, tasksid,
+						orig_tclass, false);
+}
+
 /*
  * security_bounded_transition - check whether the given
  * transition is directed to bounded, or not.