Re: [PATCH v9 1/7] ima: copy only complete measurement records across kexec

[steven chen]

On 3/5/2025 4:27 AM, Mimi Zohar wrote:
> On Wed, 2025-03-05 at 20:08 +0800, Baoquan He wrote:
> > On 03/04/25 at 11:03am, steven chen wrote:
> > > Carrying the IMA measurement list across kexec requires allocating a
> > > buffer and copying the measurement records.  Separate allocating the
> > > buffer and copying the measurement records into separate functions in
> > > order to allocate the buffer at kexec 'load' and copy the measurements
> > > at kexec 'execute'.
> > >
> > > This patch includes the following changes:
> > I don't know why one patch need include so many changes. From below log,
> > it should be split into separate patches. It may not need to make one
> > patch to reflect one change, we should at least split and wrap several
> > kind of changes to ease patch understanding and reviewing. My personal
> > opinion.
> Agreed, well explained.
>
> Mimi
>
> > >   - Refactor ima_dump_measurement_list() to move the memory allocation
> > >     to a separate function ima_alloc_kexec_file_buf() which allocates
> > >     buffer of size 'kexec_segment_size' at kexec 'load'.
> > >   - Make the local variable ima_kexec_file in ima_dump_measurement_list()
> > >     a local static to the file, so that it can be accessed from
> > >     ima_alloc_kexec_file_buf(). Compare actual memory required to ensure
> > >     there is enough memory for the entire measurement record.
> > >   - Copy only complete measurement records.
> > >   - Make necessary changes to the function ima_add_kexec_buffer() to call
> > >     the above two functions.
> > >   - Compared the memory size allocated with memory size of the entire
> > >     measurement record. Copy only complete measurement records if there
> > >     is enough memory. If there is not enough memory, it will not copy
> > >     any IMA measurement records, and this situation will result in a
> > >     failure of remote attestation.
> > >
> > > Suggested-by: Mimi Zohar <zohar@xxxxxxxxxxxxx>
> > > Signed-off-by: Tushar Sugandhi <tusharsu@xxxxxxxxxxxxxxxxxxx>
> > > Signed-off-by: steven chen <chenste@xxxxxxxxxxxxxxxxxxx>

I will split this patch into the following two patches:

    ima: define and call ima_alloc_kexec_file_buf
    ima: copy measurement records as much as possible across kexec

Thanks,

Steven