NSS: allow removing entries from netgroup hash table

There is a timed desctructor in the nss responder that, when the
entry timeout passes, removes the netgroup from the hash table while
the netgroup is freed. This patch adds a hash delete callback so that if the
netgroup is removed from the hash table with hash_delete, its hash table
pointer will be invalidated. Later, when the entry is being freed, the
destructor won't attempt to remove it from the hash table.

1 files changed, 27 insertions, 0 deletions

diff --git a/src/responder/nss/nsssrv_netgroup.c b/src/responder/nss/nsssrv_netgroup.c
index 18cd0da47..e1d3a0529 100644
--- a/src/responder/nss/nsssrv_netgroup.c
+++ b/src/responder/nss/nsssrv_netgroup.c
@@ -142,6 +142,12 @@ static int netgr_hash_remove (TALLOC_CTX *ctx)
     struct getent_ctx *netgr =
             talloc_get_type(ctx, struct getent_ctx);
 
+    if (netgr->lookup_table == NULL) {
+        DEBUG(SSSDBG_TRACE_LIBS, ("netgroup [%s] was already removed\n",
+                                  netgr->name));
+        return EOK;
+    }
+
     key.type = HASH_KEY_STRING;
     key.str = netgr->name;
 
@@ -1004,3 +1010,24 @@ int nss_cmd_endnetgrent(struct cli_ctx *client)
     sss_cmd_done(client, NULL);
     return EOK;
 }
+
+void
+netgroup_hash_delete_cb(hash_entry_t *item,
+                        hash_destroy_enum deltype, void *pvt)
+{
+    struct getent_ctx *netgr;
+
+    if (deltype != HASH_ENTRY_DESTROY) {
+        return;
+    }
+
+    netgr = talloc_get_type(item->value.ptr, struct getent_ctx);
+    if (!netgr) {
+        DEBUG(SSSDBG_OP_FAILURE, ("Invalid netgroup\n"));
+        return;
+    }
+
+    /* So that the destructor wouldn't attempt to remove the netgroup from hash
+     * table */
+    netgr->lookup_table = NULL;
+}