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

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Message-ID: <CAHC9VhS4TKvTyUB+H6cQNjRFbssGRM-U6S-X7011bSv7bHiQqg@mail.gmail.com>
Date: Mon, 26 Aug 2024 21:56:29 -0400
From: Paul Moore <paul@...l-moore.com>
To: yukaixiong <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 9:38 PM yukaixiong <yukaixiong@...wei.com> wrote:
> On 2024/8/27 6:49, Paul Moore wrote:
> > 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.
>
> According to the compilation condition in security/Makefile:
>
>                obj-$(CONFIG_MMU)            += min_addr.o
>
> if CONFIG_MMU is not defined, min_addr.c would not be included in the
> compilation process.
> So，it is okay to drop the CONFIG_MMU check.

Great, please add some text about that in the commit description as it
is an important difference in the code changes that isn't currently
documented in the patch.

-- 
paul-moore.com