1 files changed, 175 insertions, 5 deletions

diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c
index 8551952ef329..ab0cc0c7b944 100644
--- a/security/selinux/ss/services.c
+++ b/security/selinux/ss/services.c
@@ -88,6 +88,11 @@ static u32 latest_granting;
 static int context_struct_to_string(struct context *context, char **scontext,
                                     u32 *scontext_len);
 
+static int context_struct_compute_av(struct context *scontext,
+                                     struct context *tcontext,
+                                     u16 tclass,
+                                     u32 requested,
+                                     struct av_decision *avd);
 /*
  * Return the boolean value of a constraint expression
  * when it is applied to the specified source and target
@@ -274,6 +279,100 @@ mls_ops:
 }
 
 /*
+ * security_boundary_permission - drops violated permissions
+ * on boundary constraint.
+ */
+static void type_attribute_bounds_av(struct context *scontext,
+                                     struct context *tcontext,
+                                     u16 tclass,
+                                     u32 requested,
+                                     struct av_decision *avd)
+{
+        struct context lo_scontext;
+        struct context lo_tcontext;
+        struct av_decision lo_avd;
+        struct type_datum *source
+                = policydb.type_val_to_struct[scontext->type - 1];
+        struct type_datum *target
+                = policydb.type_val_to_struct[tcontext->type - 1];
+        u32 masked = 0;
+
+        if (source->bounds) {
+                memset(&lo_avd, 0, sizeof(lo_avd));
+
+                memcpy(&lo_scontext, scontext, sizeof(lo_scontext));
+                lo_scontext.type = source->bounds;
+
+                context_struct_compute_av(&lo_scontext,
+                                          tcontext,
+                                          tclass,
+                                          requested,
+                                          &lo_avd);
+                if ((lo_avd.allowed & avd->allowed) == avd->allowed)
+                        return;         /* no masked permission */
+                masked = ~lo_avd.allowed & avd->allowed;
+        }
+
+        if (target->bounds) {
+                memset(&lo_avd, 0, sizeof(lo_avd));
+
+                memcpy(&lo_tcontext, tcontext, sizeof(lo_tcontext));
+                lo_tcontext.type = target->bounds;
+
+                context_struct_compute_av(scontext,
+                                          &lo_tcontext,
+                                          tclass,
+                                          requested,
+                                          &lo_avd);
+                if ((lo_avd.allowed & avd->allowed) == avd->allowed)
+                        return;         /* no masked permission */
+                masked = ~lo_avd.allowed & avd->allowed;
+        }
+
+        if (source->bounds && target->bounds) {
+                memset(&lo_avd, 0, sizeof(lo_avd));
+                /*
+                 * lo_scontext and lo_tcontext are already
+                 * set up.
+                 */
+
+                context_struct_compute_av(&lo_scontext,
+                                          &lo_tcontext,
+                                          tclass,
+                                          requested,
+                                          &lo_avd);
+                if ((lo_avd.allowed & avd->allowed) == avd->allowed)
+                        return;         /* no masked permission */
+                masked = ~lo_avd.allowed & avd->allowed;
+        }
+
+        if (masked) {
+                struct audit_buffer *ab;
+                char *stype_name
+                        = policydb.p_type_val_to_name[source->value - 1];
+                char *ttype_name
+                        = policydb.p_type_val_to_name[target->value - 1];
+                char *tclass_name
+                        = policydb.p_class_val_to_name[tclass - 1];
+
+                /* mask violated permissions */
+                avd->allowed &= ~masked;
+
+                /* notice to userspace via audit message */
+                ab = audit_log_start(current->audit_context,
+                                     GFP_ATOMIC, AUDIT_SELINUX_ERR);
+                if (!ab)
+                        return;
+
+                audit_log_format(ab, "av boundary violation: "
+                                 "source=%s target=%s tclass=%s",
+                                 stype_name, ttype_name, tclass_name);
+                avc_dump_av(ab, tclass, masked);
+                audit_log_end(ab);
+        }
+}
+
+/*
  * Compute access vectors based on a context structure pair for
  * the permissions in a particular class.
  */
@@ -356,7 +455,7 @@ static int context_struct_compute_av(struct context *scontext,
                         avkey.source_type = i + 1;
                         avkey.target_type = j + 1;
                         for (node = avtab_search_node(&policydb.te_avtab, &avkey);
-                             node != NULL;
+                             node;
                              node = avtab_search_node_next(node, avkey.specified)) {
                                 if (node->key.specified == AVTAB_ALLOWED)
                                         avd->allowed |= node->datum.data;
@@ -404,6 +503,14 @@ static int context_struct_compute_av(struct context *scontext,
                                                         PROCESS__DYNTRANSITION);
         }
 
+        /*
+         * If the given source and target types have boundary
+         * constraint, lazy checks have to mask any violated
+         * permission and notice it to userspace via audit.
+         */
+        type_attribute_bounds_av(scontext, tcontext,
+                                 tclass, requested, avd);
+
         return 0;
 
 inval_class:
@@ -549,6 +656,69 @@ out:
         return rc;
 }
 
+/*
+ * security_bounded_transition - check whether the given
+ * transition is directed to bounded, or not.
+ * It returns 0, if @newsid is bounded by @oldsid.
+ * Otherwise, it returns error code.
+ *
+ * @oldsid : current security identifier
+ * @newsid : destinated security identifier
+ */
+int security_bounded_transition(u32 old_sid, u32 new_sid)
+{
+        struct context *old_context, *new_context;
+        struct type_datum *type;
+        int index;
+        int rc = -EINVAL;
+
+        read_lock(&policy_rwlock);
+
+        old_context = sidtab_search(&sidtab, old_sid);
+        if (!old_context) {
+                printk(KERN_ERR "SELinux: %s: unrecognized SID %u\n",
+                       __func__, old_sid);
+                goto out;
+        }
+
+        new_context = sidtab_search(&sidtab, new_sid);
+        if (!new_context) {
+                printk(KERN_ERR "SELinux: %s: unrecognized SID %u\n",
+                       __func__, new_sid);
+                goto out;
+        }
+
+        /* type/domain unchaned */
+        if (old_context->type == new_context->type) {
+                rc = 0;
+                goto out;
+        }
+
+        index = new_context->type;
+        while (true) {
+                type = policydb.type_val_to_struct[index - 1];
+                BUG_ON(!type);
+
+                /* not bounded anymore */
+                if (!type->bounds) {
+                        rc = -EPERM;
+                        break;
+                }
+
+                /* @newsid is bounded by @oldsid */
+                if (type->bounds == old_context->type) {
+                        rc = 0;
+                        break;
+                }
+                index = type->bounds;
+        }
+out:
+        read_unlock(&policy_rwlock);
+
+        return rc;
+}
+
+
 /**
  * security_compute_av - Compute access vector decisions.
  * @ssid: source security identifier
@@ -794,7 +964,7 @@ static int string_to_context_struct(struct policydb *pol,
         *p++ = 0;
 
         typdatum = hashtab_search(pol->p_types.table, scontextp);
-        if (!typdatum)
+        if (!typdatum || typdatum->attribute)
                 goto out;
 
         ctx->type = typdatum->value;
@@ -1037,7 +1207,7 @@ static int security_compute_sid(u32 ssid,
         /* If no permanent rule, also check for enabled conditional rules */
         if (!avdatum) {
                 node = avtab_search_node(&policydb.te_cond_avtab, &avkey);
-                for (; node != NULL; node = avtab_search_node_next(node, specified)) {
+                for (; node; node = avtab_search_node_next(node, specified)) {
                         if (node->key.specified & AVTAB_ENABLED) {
                                 avdatum = &node->datum;
                                 break;
@@ -2050,7 +2220,7 @@ int security_set_bools(int len, int *values)
                         policydb.bool_val_to_struct[i]->state = 0;
         }
 
-        for (cur = policydb.cond_list; cur != NULL; cur = cur->next) {
+        for (cur = policydb.cond_list; cur; cur = cur->next) {
                 rc = evaluate_cond_node(&policydb, cur);
                 if (rc)
                         goto out;
@@ -2102,7 +2272,7 @@ static int security_preserve_bools(struct policydb *p)
                 if (booldatum)
                         booldatum->state = bvalues[i];
         }
-        for (cur = p->cond_list; cur != NULL; cur = cur->next) {
+        for (cur = p->cond_list; cur; cur = cur->next) {
                 rc = evaluate_cond_node(p, cur);
                 if (rc)
                         goto out;