Re: [Linux-ima-devel] [PATCH 4/4] ima: use read_iter (generic_file_read_iter) to calculate file hash

[Mimi Z. <zo...@li...>]

On Mon, 2017-07-10 at 17:07 +0300, Dmitry Kasatkin wrote:
> On Fri, Jun 9, 2017 at 9:02 PM, Mimi Zohar <zo...@li...> wrote:
> > The large marjority of filesystems in the fs directory define
> > generic_file_read_iter as the read_iter file operation method.
> >
> > Instead of specifying the integrity_read file operation method
> > for all of these file systems, continue to calculate the file
> > hash using the read_iter method, when defined as
> > generic_file_read_iter.
> >
> > For all other read_iter methods, define an integrity_read
> > method.
> >
> > Signed-off-by: Mimi Zohar <zo...@li...>
> > ---
> >  security/integrity/iint.c | 3 +++
> >  1 file changed, 3 insertions(+)
> >
> > diff --git a/security/integrity/iint.c b/security/integrity/iint.c
> > index e3ef3fba16dc..8164f57f5cea 100644
> > --- a/security/integrity/iint.c
> > +++ b/security/integrity/iint.c
> > @@ -202,6 +202,9 @@ int integrity_kernel_read(struct file *file, loff_t offset,
> >
> >         if (file->f_op->integrity_read) {
> >                 ret = file->f_op->integrity_read(&kiocb, &iter);
> > +       } else if (file->f_op->read_iter &&
> > +                  file->f_op->read_iter == generic_file_read_iter) {
> > +               ret = file->f_op->read_iter(&kiocb, &iter);
> >         } else if (file->f_op->read) {
> >                 mm_segment_t old_fs;
> >                 char __user *buf = (char __user *)addr;
> 
> Why not __vfs_read()?? it uses new_sync_read()

and that calls read_sync_iter(), which calls ->read_iter.   Is there a
problem with directly calling ->integrity_read instead?

Mimi

> else if (file->f_op->read_iter)
>     return new_sync_read(file, buf, count, pos);
> 
>