1 files changed, 56 insertions, 6 deletions

diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c
index 2abbc49914e6..4e976f58b980 100644
--- a/security/selinux/ss/services.c
+++ b/security/selinux/ss/services.c
@@ -26,6 +26,10 @@
  *
  *  Added support for bounds domain and audit messaged on masked permissions
  *
+ * Updated: Guido Trentalancia <guido@trentalancia.com>
+ *
+ *  Added support for runtime switching of the policy type
+ *
  * Copyright (C) 2008, 2009 NEC Corporation
  * Copyright (C) 2006, 2007 Hewlett-Packard Development Company, L.P.
  * Copyright (C) 2004-2006 Trusted Computer Solutions, Inc.
@@ -232,6 +236,10 @@ static void map_decision(u16 tclass, struct av_decision *avd,
         }
 }
 
+int security_mls_enabled(void)
+{
+        return policydb.mls_enabled;
+}
 
 /*
  * Return the boolean value of a constraint expression
@@ -1550,6 +1558,8 @@ static int convert_context(u32 key,
 {
         struct convert_context_args *args;
         struct context oldc;
+        struct ocontext *oc;
+        struct mls_range *range;
         struct role_datum *role;
         struct type_datum *typdatum;
         struct user_datum *usrdatum;
@@ -1620,9 +1630,39 @@ static int convert_context(u32 key,
                 goto bad;
         c->type = typdatum->value;
 
-        rc = mls_convert_context(args->oldp, args->newp, c);
-        if (rc)
-                goto bad;
+        /* Convert the MLS fields if dealing with MLS policies */
+        if (args->oldp->mls_enabled && args->newp->mls_enabled) {
+                rc = mls_convert_context(args->oldp, args->newp, c);
+                if (rc)
+                        goto bad;
+        } else if (args->oldp->mls_enabled && !args->newp->mls_enabled) {
+                /*
+                 * Switching between MLS and non-MLS policy:
+                 * free any storage used by the MLS fields in the
+                 * context for all existing entries in the sidtab.
+                 */
+                mls_context_destroy(c);
+        } else if (!args->oldp->mls_enabled && args->newp->mls_enabled) {
+                /*
+                 * Switching between non-MLS and MLS policy:
+                 * ensure that the MLS fields of the context for all
+                 * existing entries in the sidtab are filled in with a
+                 * suitable default value, likely taken from one of the
+                 * initial SIDs.
+                 */
+                oc = args->newp->ocontexts[OCON_ISID];
+                while (oc && oc->sid[0] != SECINITSID_UNLABELED)
+                        oc = oc->next;
+                if (!oc) {
+                        printk(KERN_ERR "SELinux:  unable to look up"
+                                " the initial SIDs list\n");
+                        goto bad;
+                }
+                range = &oc->context[0].range;
+                rc = mls_range_set(c, range);
+                if (rc)
+                        goto bad;
+        }
 
         /* Check the validity of the new context. */
         if (!policydb_context_isvalid(args->newp, c)) {
@@ -1718,6 +1758,12 @@ int security_load_policy(void *data, size_t len)
         if (policydb_read(&newpolicydb, fp))
                 return -EINVAL;
 
+        /* If switching between different policy types, log MLS status */
+        if (policydb.mls_enabled && !newpolicydb.mls_enabled)
+                printk(KERN_INFO "SELinux: Disabling MLS support...\n");
+        else if (!policydb.mls_enabled && newpolicydb.mls_enabled)
+                printk(KERN_INFO "SELinux: Enabling MLS support...\n");
+
         rc = policydb_load_isids(&newpolicydb, &newsidtab);
         if (rc) {
                 printk(KERN_ERR "SELinux:  unable to load the initial SIDs\n");
@@ -1749,8 +1795,12 @@ int security_load_policy(void *data, size_t len)
         args.oldp = &policydb;
         args.newp = &newpolicydb;
         rc = sidtab_map(&newsidtab, convert_context, &args);
-        if (rc)
+        if (rc) {
+                printk(KERN_ERR "SELinux:  unable to convert the internal"
+                        " representation of contexts in the new SID"
+                        " table\n");
                 goto err;
+        }
 
         /* Save the old policydb and SID table to free later. */
         memcpy(&oldpolicydb, &policydb, sizeof policydb);
@@ -2346,7 +2396,7 @@ int security_sid_mls_copy(u32 sid, u32 mls_sid, u32 *new_sid)
         u32 len;
         int rc = 0;
 
-        if (!ss_initialized || !selinux_mls_enabled) {
+        if (!ss_initialized || !policydb.mls_enabled) {
                 *new_sid = sid;
                 goto out;
         }
@@ -2447,7 +2497,7 @@ int security_net_peersid_resolve(u32 nlbl_sid, u32 nlbl_type,
         /* we don't need to check ss_initialized here since the only way both
          * nlbl_sid and xfrm_sid are not equal to SECSID_NULL would be if the
          * security server was initialized and ss_initialized was true */
-        if (!selinux_mls_enabled) {
+        if (!policydb.mls_enabled) {
                 *peer_sid = SECSID_NULL;
                 return 0;
         }