Re: [PATCH V10 2/3] IMA: Define a new template field buf

From: Thiago Jung Bauermann <bauerman@linux.ibm.com>
To: Prakhar Srivastava <prsriva02@gmail.com>
Cc: linux-integrity@vger.kernel.org,
	linux-security-module@vger.kernel.org,
	linux-kernel@vger.kernel.org, zohar@linux.ibm.com,
	roberto.sassu@huawei.com, vgoyal@redhat.com
Subject: Re: [PATCH V10 2/3] IMA: Define a new template field buf
Date: Mon, 24 Jun 2019 19:03:35 -0300	[thread overview]
Message-ID: <87ftnyk5e0.fsf@morokweng.localdomain> (raw)
In-Reply-To: <20190624062331.388-3-prsriva02@gmail.com>

Hello Prakhar,

Prakhar Srivastava <prsriva02@gmail.com> writes:

> diff --git a/security/integrity/ima/ima_template.c b/security/integrity/ima/ima_template.c
> index 00dd5a434689..a01a17e5c581 100644
> --- a/security/integrity/ima/ima_template.c
> +++ b/security/integrity/ima/ima_template.c
> @@ -26,6 +26,7 @@ static struct ima_template_desc builtin_templates[] = {
>  	{.name = IMA_TEMPLATE_IMA_NAME, .fmt = IMA_TEMPLATE_IMA_FMT},
>  	{.name = "ima-ng", .fmt = "d-ng|n-ng"},
>  	{.name = "ima-sig", .fmt = "d-ng|n-ng|sig"},
> +	{.name = "ima-buf", .fmt = "d-ng|n-ng|buf"},
>  	{.name = "", .fmt = ""},	/* placeholder for a custom format */
>  };
>
> @@ -43,6 +44,8 @@ static const struct ima_template_field supported_fields[] = {
>  	 .field_show = ima_show_template_string},
>  	{.field_id = "sig", .field_init = ima_eventsig_init,
>  	 .field_show = ima_show_template_sig},
> +	{.field_id = "buf", .field_init = ima_eventbuf_init,
> +	 .field_show = ima_show_template_buf},
>  };
>  #define MAX_TEMPLATE_NAME_LEN 15

Currently, MAX_TEMPLATE_NAME_LEN is the length of a template that
contains all valid fields. It may make sense to increase it since
there's a new field being added.

I suggest using a sizeof() to show where the number comes from (and
which can be visually shown to be correct):

#define MAX_TEMPLATE_NAME_LEN sizeof("d|n|d-ng|n-ng|sig|buf")

The sizeof() is calculated at compile time.

--
Thiago Jung Bauermann
IBM Linux Technology Center