On 04/08/25 at 12:07am, Mimi Zohar wrote:
> On Wed, 2025-04-02 at 05:47 -0700, steven chen wrote:
> > In the current implementation, the ima_dump_measurement_list() API is
> > called during the kexec "load" phase, where a buffer is allocated and
> > the measurement records are copied. Due to this, new events added after
> > kexec load but before kexec execute are not carried over to the new kernel
> > during kexec operation
>
> Repeating this here is unnecessary.
> >
> > To allow the buffer allocation and population to be separated into distinct
> > steps, make the function local seq_file "ima_kexec_file" to a file variable.
>
> This change was already made in [PATCH v11 1/9] ima: rename variable the
> set_file "file" to "ima_kexec_file". Please remove.
>
> >
> > 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'.
> >
> > Signed-off-by: Tushar Sugandhi <tusha...@linux.microsoft.com>
> > Signed-off-by: steven chen <chen...@linux.microsoft.com>
> > ---
> > security/integrity/ima/ima_kexec.c | 46 +++++++++++++++++++++++-------
> > 1 file changed, 35 insertions(+), 11 deletions(-)
> >
> > diff --git a/security/integrity/ima/ima_kexec.c
> > b/security/integrity/ima/ima_kexec.c
> > index 650beb74346c..b12ac3619b8f 100644
> > --- a/security/integrity/ima/ima_kexec.c
> > +++ b/security/integrity/ima/ima_kexec.c
> > @@ -15,26 +15,46 @@
> > #include "ima.h"
> >
> > #ifdef CONFIG_IMA_KEXEC
> > +static struct seq_file ima_kexec_file;
> > +
> > +static void ima_free_kexec_file_buf(struct seq_file *sf)
> > +{
> > + vfree(sf->buf);
> > + sf->buf = NULL;
> > + sf->size = 0;
> > + sf->read_pos = 0;
> > + sf->count = 0;
> > +}
> > +
> > +static int ima_alloc_kexec_file_buf(size_t segment_size)
> > +{
> > + ima_free_kexec_file_buf(&ima_kexec_file);
>
> After moving the vfree() here at this stage in the patch set, the IMA
> measurement list fails to verify when doing two consecutive "kexec -s -l"
> with/without a "kexec -s -u" in between. Only after "ima: kexec: move IMA log
> copy from kexec load to execute" the IMA measurement list verifies properly
> with
> the vfree() here.
I also noticed this, patch 7 will remedy this. Put patch 7 just after
this patch or squash it into this patch?
[PATCH v11 7/9] ima: verify if the segment size has changed
>
> > +
> > + /* segment size can't change between kexec load and execute */
> > + ima_kexec_file.buf = vmalloc(segment_size);
> > + if (!ima_kexec_file.buf)
> > + return -ENOMEM;
> > +
> > + ima_kexec_file.size = segment_size;
> > + ima_kexec_file.read_pos = 0;
> > + ima_kexec_file.count = sizeof(struct ima_kexec_hdr); /* reserved
> > space */
> > +
> > + return 0;
> > +}
> > +
>
