Re: [PATCH v4 1/7] kexec_file: allow to place kexec_buf randomly

Coiby Xu
2024-06-07T12:28:10Z

On Tue, Jun 04, 2024 at 03:41:35PM +0800, Baoquan He wrote:
>On 05/23/24 at 01:04pm, Coiby Xu wrote:
>> Currently, kexec_buf is placed in order which means for the same
>> machine, the info in the kexec_buf is always located at the same
>> position each time the machine is booted. This may cause a risk for
>> sensitive information like LUKS volume key. Now struct kexec_buf has a
>> new field random which indicates it's supposed to be placed in a random
>> position.
>>
>> Suggested-by: Jan Pazdziora <jpazdziora@redhat.com>
>> Signed-off-by: Coiby Xu <coxu@redhat.com>
>> ---
>> include/linux/kexec.h | 2 ++
>> kernel/kexec_file.c | 15 +++++++++++++++
>> 2 files changed, 17 insertions(+)
>>
>> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
>> index f0e9f8eda7a3..cc81b8a903ab 100644
>> --- a/include/linux/kexec.h
>> +++ b/include/linux/kexec.h
[...]
>> @@ -445,6 +456,8 @@ static int locate_mem_hole_top_down(unsigned long start, unsigned long end,
>>
>> temp_end = min(end, kbuf->buf_max);
>> temp_start = temp_end - kbuf->memsz + 1;
>> + if (kbuf->random)
>> + temp_start = kexec_random_start(temp_start, temp_end);
>
>As we discussed before, this need be limited in kdump scope, seems v4
>doesn't include the change.

Yes, v4 was sent mainly for you to review the patches by applying to
latest Linus tree. v5 now include the change.

--
Best regards,
Coiby