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

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Message-Id: <1581554308.8515.108.camel@linux.ibm.com>
Date:   Wed, 12 Feb 2020 19:38:28 -0500
From:   Mimi Zohar <zohar@...ux.ibm.com>
To:     Shuah Khan <skhan@...uxfoundation.org>,
        James Bottomley <James.Bottomley@...senPartnership.com>,
        Tushar Sugandhi <tusharsu@...ux.microsoft.com>,
        joe@...ches.com, linux-integrity@...r.kernel.org
Cc:     sashal@...nel.org, nramas@...ux.microsoft.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 3/3] IMA: Add module name and base name prefix to log.

On Wed, 2020-02-12 at 15:52 -0700, Shuah Khan wrote:
> 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@...ux.microsoft.com>
> >>> Reviewed-by: Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>
> >>> Suggested-by: Joe Perches <joe@...ches.com>
> >>> Suggested-by: Shuah Khan <skhan@...uxfoundation.org>
> >>
> >> <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@...ibm.com>
> >>>    */
> >>>   
> >>> +#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.  Tushar, I don't see any need for changing the existing
IMA/EVM messages.  Either remove the KBUILD_BASENAME from the format
or limit the new format to the integrity directory.

thanks,

Mimi