tools/ocaml/xenstored: Synchronise defaults with oxenstore.conf.in

We currently have 2 different set of defaults in upstream Xen git tree:
* defined in the source code, only used if there is no config file
* defined in the oxenstored.conf.in upstream Xen

An oxenstored.conf file is not mandatory, and if missing, maxrequests in
particular has an unsafe default.

Resync the defaults from oxenstored.conf.in into the source code.

This is part of XSA-326 / CVE-2022-42316.

Signed-off-by: Edwin Török <edvin.torok@citrix.com>
Acked-by: Christian Lindig <christian.lindig@citrix.com>
(cherry picked from commit 84734955d4)

tools/ocaml/xenstored/define.ml

@@ -22,9 +22,9 @@ let xs_daemon_socket_ro = Paths.xen_run_stored ^ "/socket_ro"
 
 let default_config_dir = Paths.xen_config_dir
 
-let maxwatch = ref (50)
-let maxtransaction = ref (20)
-let maxrequests = ref (-1)   (* maximum requests per transaction *)
+let maxwatch = ref (100)
+let maxtransaction = ref (10)
+let maxrequests = ref (1024)   (* maximum requests per transaction *)
 
 let conflict_burst_limit = ref 5.0
 let conflict_max_history_seconds = ref 0.05

tools/ocaml/xenstored/quota.ml

@@ -20,8 +20,8 @@ exception Transaction_opened
 
 let warn fmt = Logging.warn "quota" fmt
 let activate = ref true
-let maxent = ref (10000)
-let maxsize = ref (4096)
+let maxent = ref (1000)
+let maxsize = ref (2048)
 
 type t = {
 	maxent: int;               (* max entities per domU *)