linux-kernel - Re: [PATCH v2 3/9] security: define security_kernel_read

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Message-Id: <1526666133.3404.67.camel@linux.vnet.ibm.com>
Date:   Fri, 18 May 2018 13:55:33 -0400
From:   Mimi Zohar <zohar@...ux.vnet.ibm.com>
To:     James Morris <jmorris@...ei.org>,
        "Eric W. Biederman" <ebiederm@...ssion.com>
Cc:     Casey Schaufler <casey@...aufler-ca.com>,
        linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        linux-kernel@...r.kernel.org, David Howells <dhowells@...hat.com>,
        "Luis R . Rodriguez" <mcgrof@...nel.org>,
        kexec@...ts.infradead.org, Andres Rodriguez <andresx7@...il.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Kees Cook <keescook@...omium.org>
Subject: Re: [PATCH v2 3/9] security: define security_kernel_read_blob()
 wrapper

On Sat, 2018-05-19 at 03:13 +1000, James Morris wrote:
> On Thu, 17 May 2018, Eric W. Biederman wrote:
> 
> > Nacked-by: "Eric W. Biederman" <ebiederm@...ssion.com>
> > 
> > Nack on this sharing nonsense.  These two interfaces do not share any
> > code in their implementations other than the if statement to distinguish
> > between the two cases.
> 
> Hmm, it's not even doing that.
> 
> There's already an if(!file && read_id == X) { } check and this is another 
> one being added.
> 
> > If we want comprehensible and maintainable code in the security modules
> > we need to split these two pieces of functionality apart.
> 
> All ima_read is doing in both the old and new case is checking if there's 
> no file then if it's a certain operation, returning an error.
> 
> To echo Eric and Casey's suggestions, how about changing the name of the 
> hook to security_kernel_read_data() ?

Thanks, James.  Somehow I missed this option.  Renaming the existing
hook, would be the easiest solution.  Eric, are you in agreement with
James' naming suggestion/solution?

> Then ima_read_file() can be changed to ima_read_data(), and then instead 
> of two if (!file && read_id == X) checks, have:
> 
> 	if (!file) {
> 		switch (read_id) {
> 		}
> 	}
> 
> 
> 
>