linux-kernel - Re: [PATCH -next 07/15] security: min_addr: move sysctl into its own file

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Message-ID: <CAHC9VhS=5k3zZyuuon2c6Lsf5GixAra6+d3A4bG2FVytv33n_w@mail.gmail.com>
Date: Mon, 26 Aug 2024 18:49:17 -0400
From: Paul Moore <paul@...l-moore.com>
To: Kaixiong Yu <yukaixiong@...wei.com>
Cc: akpm@...ux-foundation.org, mcgrof@...nel.org, ysato@...rs.sourceforge.jp, 
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	wangkefeng.wang@...wei.com
Subject: Re: [PATCH -next 07/15] security: min_addr: move sysctl into its own file

On Mon, Aug 26, 2024 at 8:05 AM Kaixiong Yu <yukaixiong@...wei.com> wrote:
>
> The dac_mmap_min_addr belongs to min_addr.c, move it into
> its own file from /kernel/sysctl.c. In the previous Linux kernel
> boot process, sysctl_init_bases needs to be executed before
> init_mmap_min_addr, So, register_sysctl_init should be executed
> before update_mmap_min_addr in init_mmap_min_addr.
>
> Signed-off-by: Kaixiong Yu <yukaixiong@...wei.com>
> ---
>  kernel/sysctl.c     |  9 ---------
>  security/min_addr.c | 11 +++++++++++
>  2 files changed, 11 insertions(+), 9 deletions(-)
>
> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> index 41d4afc978e6..0c0bab3dad7d 100644
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -2059,15 +2059,6 @@ static struct ctl_table vm_table[] = {
>                 .proc_handler   = proc_dointvec_minmax,
>                 .extra1         = SYSCTL_ZERO,
>         },
> -#ifdef CONFIG_MMU
> -       {
> -               .procname       = "mmap_min_addr",
> -               .data           = &dac_mmap_min_addr,
> -               .maxlen         = sizeof(unsigned long),
> -               .mode           = 0644,
> -               .proc_handler   = mmap_min_addr_handler,
> -       },
> -#endif
>  #if (defined(CONFIG_X86_32) && !defined(CONFIG_UML))|| \
>     (defined(CONFIG_SUPERH) && defined(CONFIG_VSYSCALL))
>         {
> diff --git a/security/min_addr.c b/security/min_addr.c
> index 0ce267c041ab..b2f61649e110 100644
> --- a/security/min_addr.c
> +++ b/security/min_addr.c
> @@ -44,8 +44,19 @@ int mmap_min_addr_handler(const struct ctl_table *table, int write,
>         return ret;
>  }
>
> +static struct ctl_table min_addr_sysctl_table[] = {
> +       {
> +               .procname       = "mmap_min_addr",
> +               .data           = &dac_mmap_min_addr,
> +               .maxlen         = sizeof(unsigned long),
> +               .mode           = 0644,
> +               .proc_handler   = mmap_min_addr_handler,
> +       },
> +};

I haven't chased all of the Kconfig deps to see if there is a problem,
but please provide a quick explanation in the commit description about
why it is okay to drop the CONFIG_MMU check.

>  static int __init init_mmap_min_addr(void)
>  {
> +       register_sysctl_init("vm", min_addr_sysctl_table);
>         update_mmap_min_addr();
>
>         return 0;
> --
> 2.25.1

-- 
paul-moore.com