Re: [PATCH 2/3 v5] add a new template field buf to contain the buffer

[Roberto Sassu]

On 5/14/2019 7:07 AM, prakhar srivastava wrote:
> On Mon, May 13, 2019 at 6:48 AM Roberto Sassu <roberto.sassu@xxxxxxxxxx> wrote:
> > On 5/11/2019 12:37 AM, Prakhar Srivastava wrote:
> > > From: Prakhar Srivastava <prsriva02@xxxxxxxxx>
> > >
> > > The buffer(cmdline args) added to the ima log cannot be attested
> > > without having the actual buffer. Thus to make the measured buffer
> > > available to store/read a new ima template (buf) is added.
> >
> > Hi Prakhar
> >
> > please fix the typos. More comments below.
> >
> >
> > > +     buffer_event_data->type = IMA_XATTR_BUFFER;
> > > +     buffer_event_data->buf_length = size;
> > > +     memcpy(buffer_event_data->buf, buf, size);
> > > +
> > > +     event_data.xattr_value = (struct evm_ima_xattr_data *)buffer_event_data;
> > > +     event_data.xattr_len = alloc_length;
> >
> > I would prefer that you introduce two new fields in the ima_event_data
> > structure. You can initialize them directly with the parameters of
> > process_buffer_measurement().
> I will make the edits, this will definitely save the kzalloc in this code
> path.
> > ima_write_template_field_data() will make
> > a copy.
> Since event_data->type is used to distinguish what the template field
>   should contain.
> Removing the type and subsequent check in the template_init,
>   buf template fmt will result in the whole event_Data structure
> being added to the log, which is not the expected output.
> For buffer entries, the buf templet fmt will contains the buffer itself.

The purpose of ima_event_data is to pass data to the init method of
template fields. Each method takes the data it needs.

If you pass event_data->buf and event_data->buf_len to
ima_write_template_field_data() this should be fine.

Roberto


> > > +      .field_show = ima_show_template_buf},
> >
> > Please update Documentation/security/IMA-templates.rst
> Will update the documentation.
>
> Thanks,
> Prakhar Srivastava
> > Thanks
> >
> > Roberto

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