linux-kernel - Re: [PATCH V8 1/3] Define a new IMA hook to measure the boot command line arguments

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Date:   Fri, 14 Jun 2019 10:48:55 -0700
From:   prakhar srivastava <prsriva02@...il.com>
To:     Mimi Zohar <zohar@...ux.ibm.com>
Cc:     linux-integrity <linux-integrity@...r.kernel.org>,
        linux-security-module@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Roberto Sassu <roberto.sassu@...wei.com>, vgoyal@...hat.com
Subject: Re: [PATCH V8 1/3] Define a new IMA hook to measure the boot command
 line arguments

On Thu, Jun 13, 2019 at 12:22 PM Mimi Zohar <zohar@...ux.ibm.com> wrote:
>
> Hi Prakhar,
>
> Patches titles in the subject line need to be prefixed with the
> subsystem, in this case "ima: ".
>
> On Wed, 2019-06-12 at 15:15 -0700, Prakhar Srivastava wrote:
> > This patch adds support in ima to measure kexec cmdline args
> > during soft reboot(kexec_file_load).
>
> Based on the patch title, the word "ima" is redundant.  Patch
> descriptions are suppose to be written in the third person. "This
> patch adds" is unnecessary.  Please review section 3 "Describe your
> changes" in Documentation/process/submitting-patches.rst.
>
> >
> > - A new ima hook ima_kexec_cmdline is defined to be called by the
> > kexec code.
> > - A new function process_buffer_measurement is defined to measure
> > the buffer hash into the ima log.
> > - A new func policy KEXEC_CMDLINE is defined to control the
> >  measurement.[Suggested by Mimi]
> >
> > Signed-off-by: Prakhar Srivastava <prsriva02@...il.com>
>
>
> > diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
> > index fd9b01881d17..98e351e13557 100644
> > --- a/security/integrity/ima/ima_policy.c
> > +++ b/security/integrity/ima/ima_policy.c
> > @@ -292,6 +292,13 @@ static bool ima_match_rules(struct ima_rule_entry *rule, struct inode *inode,
> >  {
> >       int i;
> >
> > +     /* only incase of KEXEC_CMDLINE, inode is NULL */
> > +     if (func == KEXEC_CMDLINE) {
> > +             if ((rule->flags & IMA_FUNC) &&
> > +                     (rule->func == func) && (!inode))
>
> Thank you for fixing the other formatting issues.  Here's another one.
>  Is checking !inode needed?
Since i am adding a new type(buffer) for measurement, and only
one (file or buffer) can be passed in, this is guarding against passing
the func as KEXEC_CMDLINE for a file.
I will remove it, since the check will still return true/false, if the
rule doesn't
exist.

and fix other formatting issues.
Thanks,
- Prakhar Srivastava
> Mimi
>
> > +                     return true;
> > +             return false;
> > +     }
> >       if ((rule->flags & IMA_FUNC) &&
> >           (rule->func != func && func != POST_SETATTR))
> >               return false;
> >
>