Re: [PATCH v3 3/3] IMA: Add module name and base name prefix to log.

[Shuah Khan]

On 2/12/20 8:26 AM, James Bottomley wrote:
> On Wed, 2020-02-12 at 09:29 -0500, Mimi Zohar wrote:
> > On Tue, 2020-02-11 at 15:14 -0800, Tushar Sugandhi wrote:
> > > The #define for formatting log messages, pr_fmt, is duplicated in
> > > the
> > > files under security/integrity.
> > >
> > > This change moves the definition to security/integrity/integrity.h
> > > and
> > > removes the duplicate definitions in the other files under
> > > security/integrity. Also, it adds KBUILD_MODNAME and
> > > KBUILD_BASENAME prefix
> > > to the log messages.
> > >
> > > Signed-off-by: Tushar Sugandhi <tusharsu@xxxxxxxxxxxxxxxxxxx>
> > > Reviewed-by: Lakshmi Ramasubramanian <nramas@xxxxxxxxxxxxxxxxxxx>
> > > Suggested-by: Joe Perches <joe@xxxxxxxxxxx>
> > > Suggested-by: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>
> >
> > <snip>
> >
> > > diff --git a/security/integrity/integrity.h
> > > b/security/integrity/integrity.h
> > > index 73fc286834d7..b1bb4d2263be 100644
> > > --- a/security/integrity/integrity.h
> > > +++ b/security/integrity/integrity.h
> > > @@ -6,6 +6,12 @@
> > >    * Mimi Zohar <zohar@xxxxxxxxxx>
> > >    */
> > >   
> > > +#ifdef pr_fmt
> > > +#undef pr_fmt
> > > +#endif
> > > +
> > > +#define pr_fmt(fmt) KBUILD_MODNAME ": " KBUILD_BASENAME ": " fmt
> > > +
> > >   #include <linux/types.h>
> > >   #include <linux/integrity.h>
> > >   #include <crypto/sha.h>
> >
> > Joe, Shuah, including the pr_fmt() in integrity/integrity.h not only
> > affects the integrity directory but everything below it.  Adding
> > KBUILD_BASENAME to pr_fmt() modifies all of the existing IMA and EVM
> > kernel messages.  Is that ok or should there be a separate pr_fmt()
> > for the subdirectories?

> Log messages are often consumed by log monitors, which mostly use
> pattern matching to find messages they're interested in, so you have to
> take some care when changing the messages the kernel spits out and you
> have to make sure any change gets well notified so the distributions
> can warn about it.
>
> For this one, can we see a "before" and "after" message so we know
> what's happening?

Mimi and James,

My suggestion was based on thinking that simplifying this by removing
duplicate defines. Some messages are missing modules names, adding
module name to them does change the messages.

If using one pr_fmt for all modules changes the world and makes it
difficult for log monitors, I would say it isn't a good change.

I will leave this totally up to Mimi to decide. Feel free to throw
out my suggestion if it leads more trouble than help. :)

thanks,
-- Shuah