Re: [PATCH v9 6/8] powerpc: Move ima_get_kexec_buffer() and ima_free_kexec_buffer() to ima

[Lakshmi Ramasubramanian]

On 12/1/20 3:38 AM, Mimi Zohar wrote:
> Hi Lakshmi,
>
> On Fri, 2020-11-13 at 11:22 -0800, Lakshmi Ramasubramanian wrote:
> > ima_get_kexec_buffer() retrieves the address and size of the buffer
> > used for carrying forward the IMA measurement logs on kexec from
> > the device tree.
> >
> > ima_free_kexec_buffer() removes the chosen node namely
> > "linux,ima-kexec-buffer" from the device tree, and frees the buffer
> > used for carrying forward the IMA measurement logs on kexec.
> >
> > These functions do not have architecture specific code, but are
> > currently limited to powerpc.
> >
> > Move ima_get_kexec_buffer() and ima_free_kexec_buffer() to ima_kexec.c
> > in IMA so that they are accessible for other architectures as well.
>
> This sentence flows from the previous line.  No need for separate
> paragraphs here.

Sure - will update Mimi.

> > With the above change the functions in arch/powerpc/kexec/ima.c are
> > defined only when the kernel config CONFIG_IMA_KEXEC is enabled.
> > Update the Makefile to build arch/powerpc/kexec/ima.c only when
> > CONFIG_IMA_KEXEC is enabled and remove "#ifdef CONFIG_IMA_KEXEC"
> > in arch/powerpc/kexec/ima.c.
> >
> > Co-developed-by: Prakhar Srivastava <prsriva@xxxxxxxxxxxxxxxxxxx>
> > Signed-off-by: Prakhar Srivastava <prsriva@xxxxxxxxxxxxxxxxxxx>
> > Signed-off-by: Lakshmi Ramasubramanian <nramas@xxxxxxxxxxxxxxxxxxx>
>
> After making the two changes,
>
> Reviewed-by: Mimi Zohar <zohar@xxxxxxxxxxxxx>
>
>
> > diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c
> > index 121de3e04af2..3f0fa2673dd3 100644
> > --- a/security/integrity/ima/ima_kexec.c
> > +++ b/security/integrity/ima/ima_kexec.c
> > @@ -9,9 +9,60 @@
> >   
> >   #include <linux/seq_file.h>
> >   #include <linux/vmalloc.h>
> > +#include <linux/memblock.h>
> > +#include <linux/of.h>
> >   #include <linux/kexec.h>
> > +#include <linux/ima.h>
> >   #include "ima.h"
> >   
> > +/**
> > + * ima_get_kexec_buffer - get IMA buffer from the previous kernel
> > + * @addr:	On successful return, set to point to the buffer contents.
> > + * @size:	On successful return, set to the buffer size.
> > + *
> > + * Return: 0 on success, negative errno on error.
> > + */
> > +static int ima_get_kexec_buffer(void **addr, size_t *size)
> > +{
> > +	int ret;
> > +	unsigned long tmp_addr;
> > +	size_t tmp_size;
> > +
> > +	ret = get_ima_kexec_buffer(NULL, 0, &tmp_addr, &tmp_size);
> > +	if (ret)
> > +		return ret;
> > +
> > +	*addr = __va(tmp_addr);
> > +	*size = tmp_size;
> > +
> > +	return 0;
> > +}
> > +
> > +/**
> > + * ima_free_kexec_buffer - free memory used by the IMA buffer
> > + */
> > +static int ima_free_kexec_buffer(void)
> > +{
> > +	int ret;
> > +	unsigned long addr;
> > +	size_t size;
> > +	struct property *prop;
> > +
> > +	prop = of_find_property(of_chosen, "linux,ima-kexec-buffer", NULL);
> > +	if (!prop)
> > +		return -ENOENT;
> > +
> > +	ret = get_ima_kexec_buffer(NULL, 0, &addr, &size);
> > +	if (ret)
> > +		return ret;
> > +
> > +	ret = of_remove_property(of_chosen, prop);
> > +	if (ret)
> > +		return ret;
> > +
> > +	return memblock_free(addr, size);
> > +}
> > +
>
> Please move these functions, after the ifdef below, before the function
> where they're used.

Will make the above change.

thanks,
 -lakshmi

> >   #ifdef CONFIG_IMA_KEXEC
> >   static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer,
> >   				     unsigned long segment_size)