mqueue: revert bump up DFLT_*MAX

Mqueue limitation is slightly naieve parameter likes other ipcs because
unprivileged user can consume kernel memory by using ipcs.

Thus, too aggressive raise bring us security issue.  Example, current
setting allow evil unprivileged user use 256GB (= 256 * 1024 * 1024*1024)
and it's enough large to system will belome unresponsive.  Don't do that.

Instead, every admin should adjust the knobs for their own systems.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Doug Ledford <dledford@redhat.com>
Acked-by: Joe Korty <joe.korty@ccur.com>
Cc: Amerigo Wang <amwang@redhat.com>
Acked-by: Serge E. Hallyn <serue@us.ibm.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/ipc_namespace.h b/include/linux/ipc_namespace.h
index 6e1dd08..2488535 100644 (file)
--- a/include/linux/ipc_namespace.h
+++ b/include/linux/ipc_namespace.h
@@ -118,12 +118,12 @@ extern int mq_init_ns(struct ipc_namespace *ns);
 #define DFLT_QUEUESMAX               256
 #define HARD_QUEUESMAX              1024
 #define MIN_MSGMAX                     1
-#define DFLT_MSG                      64U
-#define DFLT_MSGMAX                 1024
+#define DFLT_MSG                      10U
+#define DFLT_MSGMAX                   10
 #define HARD_MSGMAX                65536
 #define MIN_MSGSIZEMAX               128
 #define DFLT_MSGSIZE                8192U
-#define DFLT_MSGSIZEMAX               (1024*1024)
+#define DFLT_MSGSIZEMAX                     8192
 #define HARD_MSGSIZEMAX            (16*1024*1024)
 #else
 static inline int mq_init_ns(struct ipc_namespace *ns) { return 0; }