[LTP] [PATCH] userns/userns08.c: Enable userns in max_user_namespaces file

[xuyang2018.jy@fujitsu.com <xuyang2018.jy@fujitsu.com>]

Hi!

My machine's time is wrong, so I sent this patch today but the email's
date is 8.5(It may lose your attention).

Best Regards
Yang Xu
> On old distros ie centos7, the default value of max_user_namespaces is set to 0.
> Enable it by increasing this value.
> 
> Signed-off-by: Yang Xu<xuyang2018.jy@fujitsu.com>
> ---
>   testcases/kernel/containers/userns/userns08.c | 9 +++++++++
>   1 file changed, 9 insertions(+)
> 
> diff --git a/testcases/kernel/containers/userns/userns08.c b/testcases/kernel/containers/userns/userns08.c
> index aedfc6c4e..0910ea7d4 100644
> --- a/testcases/kernel/containers/userns/userns08.c
> +++ b/testcases/kernel/containers/userns/userns08.c
> @@ -120,6 +120,11 @@ static void setup(void)
> 
>   	SAFE_WRITE(fd, 1, "\n", 1);
>   	SAFE_CLOSE(fd);
> +
> +	/* The default value of max_user_namespaces is set to 0 on some distros,
> +	 * We need to change the default value to call clone().
> +	 */
> +	SAFE_FILE_PRINTF("/proc/sys/user/max_user_namespaces", "%d", 10);
>   }
> 
>   static struct tst_test test = {
> @@ -133,6 +138,10 @@ static struct tst_test test = {
>   		"CONFIG_USER_NS",
>   		NULL
>   	},
> +	.save_restore = (const char * const[]) {
> +		"?/proc/sys/user/max_user_namespaces",
> +		NULL,
> +	},
>   	.tags = (const struct tst_tag[]) {
>   		{"linux-git", "d2f007dbe7e4"},
>   		{"CVE", "CVE-2018-18955"},