From b376c3e1b6770ddcb4f0782be16358095fcea0b6 Mon Sep 17 00:00:00 2001
From: "Eric W. Biederman" <ebiederm@xmission.com>
Date: Mon, 8 Aug 2016 13:41:24 -0500
Subject: userns: Add a limit on the number of user namespaces

Export the export the maximum number of user namespaces as
/proc/sys/userns/max_user_namespaces.

Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 kernel/fork.c | 2 ++
 1 file changed, 2 insertions(+)

(limited to 'kernel/fork.c')

diff --git a/kernel/fork.c b/kernel/fork.c
index 52e725d4a866..daa6a82b4900 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -321,6 +321,8 @@ void __init fork_init(void)
 	init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
 	init_task.signal->rlim[RLIMIT_SIGPENDING] =
 		init_task.signal->rlim[RLIMIT_NPROC];
+
+	init_user_ns.max_user_namespaces = max_threads;
 }
 
 int __weak arch_dup_task_struct(struct task_struct *dst,
-- 
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