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

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Message-ID: <aeb685e9-3a2d-13b4-4ec8-0752ded06d61@huawei.com>
Date: Tue, 27 Aug 2024 09:38:21 +0800
From: yukaixiong <yukaixiong@...wei.com>
To: Paul Moore <paul@...l-moore.com>
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Subject: Re: [PATCH -next 07/15] security: min_addr: move sysctl into its own
 file



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.
>>   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