netlabel: Replace protocol/NetLabel linking with refrerence counts

NetLabel has always had a list of backpointers in the CIPSO DOI definition
structure which pointed to the NetLabel LSM domain mapping structures which
referenced the CIPSO DOI struct.  The rationale for this was that when an
administrator removed a CIPSO DOI from the system all of the associated
NetLabel LSM domain mappings should be removed as well; a list of
backpointers made this a simple operation.

Unfortunately, while the backpointers did make the removal easier they were
a bit of a mess from an implementation point of view which was making
further development difficult.  Since the removal of a CIPSO DOI is a
realtively rare event it seems to make sense to remove this backpointer
list as the optimization was hurting us more then it was helping.  However,
we still need to be able to track when a CIPSO DOI definition is being used
so replace the backpointer list with a reference count.  In order to
preserve the current functionality of removing the associated LSM domain
mappings when a CIPSO DOI is removed we walk the LSM domain mapping table,
removing the relevant entries.

Signed-off-by: Paul Moore <paul.moore@hp.com>
Reviewed-by: James Morris <jmorris@namei.org>

1 files changed, 47 insertions, 48 deletions

diff --git a/net/netlabel/netlabel_domainhash.c b/net/netlabel/netlabel_domainhash.c
index dc42206c431..0243f0c57b4 100644
--- a/net/netlabel/netlabel_domainhash.c
+++ b/net/netlabel/netlabel_domainhash.c
@@ -217,20 +217,6 @@ int netlbl_domhsh_add(struct netlbl_dom_map *entry,
         u32 bkt;
         struct audit_buffer *audit_buf;
 
-        switch (entry->type) {
-        case NETLBL_NLTYPE_UNLABELED:
-                ret_val = 0;
-                break;
-        case NETLBL_NLTYPE_CIPSOV4:
-                ret_val = cipso_v4_doi_domhsh_add(entry->type_def.cipsov4,
-                                                  entry->domain);
-                break;
-        default:
-                return -EINVAL;
-        }
-        if (ret_val != 0)
-                return ret_val;
-
         entry->valid = 1;
         INIT_RCU_HEAD(&entry->rcu);
 
@@ -271,16 +257,6 @@ int netlbl_domhsh_add(struct netlbl_dom_map *entry,
         }
         rcu_read_unlock();
 
-        if (ret_val != 0) {
-                switch (entry->type) {
-                case NETLBL_NLTYPE_CIPSOV4:
-                        if (cipso_v4_doi_domhsh_remove(entry->type_def.cipsov4,
-                                                       entry->domain) != 0)
-                                BUG();
-                        break;
-                }
-        }
-
         return ret_val;
 }
 
@@ -302,35 +278,26 @@ int netlbl_domhsh_add_default(struct netlbl_dom_map *entry,
 }
 
 /**
- * netlbl_domhsh_remove - Removes an entry from the domain hash table
- * @domain: the domain to remove
+ * netlbl_domhsh_remove_entry - Removes a given entry from the domain table
+ * @entry: the entry to remove
  * @audit_info: NetLabel audit information
  *
  * Description:
  * Removes an entry from the domain hash table and handles any updates to the
- * lower level protocol handler (i.e. CIPSO).  Returns zero on success,
- * negative on failure.
+ * lower level protocol handler (i.e. CIPSO).  Caller is responsible for
+ * ensuring that the RCU read lock is held.  Returns zero on success, negative
+ * on failure.
  *
  */
-int netlbl_domhsh_remove(const char *domain, struct netlbl_audit *audit_info)
+int netlbl_domhsh_remove_entry(struct netlbl_dom_map *entry,
+                               struct netlbl_audit *audit_info)
 {
-        int ret_val = -ENOENT;
-        struct netlbl_dom_map *entry;
+        int ret_val = 0;
         struct audit_buffer *audit_buf;
 
-        rcu_read_lock();
-        if (domain)
-                entry = netlbl_domhsh_search(domain);
-        else
-                entry = netlbl_domhsh_search_def(domain);
         if (entry == NULL)
-                goto remove_return;
-        switch (entry->type) {
-        case NETLBL_NLTYPE_CIPSOV4:
-                cipso_v4_doi_domhsh_remove(entry->type_def.cipsov4,
-                                           entry->domain);
-                break;
-        }
+                return -ENOENT;
+
         spin_lock(&netlbl_domhsh_lock);
         if (entry->valid) {
                 entry->valid = 0;
@@ -338,8 +305,8 @@ int netlbl_domhsh_remove(const char *domain, struct netlbl_audit *audit_info)
                         list_del_rcu(&entry->list);
                 else
                         rcu_assign_pointer(netlbl_domhsh_def, NULL);
-                ret_val = 0;
-        }
+        } else
+                ret_val = -ENOENT;
         spin_unlock(&netlbl_domhsh_lock);
 
         audit_buf = netlbl_audit_start_common(AUDIT_MAC_MAP_DEL, audit_info);
@@ -351,10 +318,42 @@ int netlbl_domhsh_remove(const char *domain, struct netlbl_audit *audit_info)
                 audit_log_end(audit_buf);
         }
 
-remove_return:
-        rcu_read_unlock();
-        if (ret_val == 0)
+        if (ret_val == 0) {
+                switch (entry->type) {
+                case NETLBL_NLTYPE_CIPSOV4:
+                        cipso_v4_doi_putdef(entry->type_def.cipsov4);
+                        break;
+                }
                 call_rcu(&entry->rcu, netlbl_domhsh_free_entry);
+        }
+
+        return ret_val;
+}
+
+/**
+ * netlbl_domhsh_remove - Removes an entry from the domain hash table
+ * @domain: the domain to remove
+ * @audit_info: NetLabel audit information
+ *
+ * Description:
+ * Removes an entry from the domain hash table and handles any updates to the
+ * lower level protocol handler (i.e. CIPSO).  Returns zero on success,
+ * negative on failure.
+ *
+ */
+int netlbl_domhsh_remove(const char *domain, struct netlbl_audit *audit_info)
+{
+        int ret_val;
+        struct netlbl_dom_map *entry;
+
+        rcu_read_lock();
+        if (domain)
+                entry = netlbl_domhsh_search(domain);
+        else
+                entry = netlbl_domhsh_search_def(domain);
+        ret_val = netlbl_domhsh_remove_entry(entry, audit_info);
+        rcu_read_unlock();
+
         return ret_val;
 }