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From: Dmitry Kasatkin <dmitry.kasatkin@gmail.com>
To: Mimi Zohar <zohar@linux.vnet.ibm.com>
Cc: linux-security-module <linux-security-module@vger.kernel.org>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	David Woodhouse <dwmw2@infradead.org>,
	Kees Cook <keescook@chromium.org>,
	kexec@lists.infradead.org, linux-modules@vger.kernel.org,
	Rusty Russell <rusty@rustcorp.com.au>,
	David Howells <dhowells@redhat.com>,
	fsdevel@vger.kernel.org,
	Dmitry Torokhov <dmitry.torokhov@gmail.com>,
	"Luis R. Rodriguez" <mcgrof@suse.com>
Subject: Re: [PATCH v3 19/22] ima: support for kexec image and initramfs
Date: Thu, 11 Feb 2016 10:47:41 +0200
Message-ID: <CACE9dm-VTDNaEJPGamhMY239LQAPCRYp9rvnwbmZijyo7Vh43g@mail.gmail.com> (raw)
In-Reply-To: <1455156500.2538.268.camel@linux.vnet.ibm.com>

On Thu, Feb 11, 2016 at 4:08 AM, Mimi Zohar <zohar@linux.vnet.ibm.com> wrote:
> On Thu, 2016-02-11 at 01:55 +0200, Dmitry Kasatkin wrote:
>> On Feb 11, 2016 1:22 AM, "Mimi Zohar" <zohar@linux.vnet.ibm.com> wrote:
>> >
>> > On Wed, 2016-02-10 at 23:09 +0200, Dmitry Kasatkin wrote:
>> > > On Wed, Feb 3, 2016 at 9:06 PM, Mimi Zohar <zohar@linux.vnet.ibm.com>
>> wrote:
>
>> > > >
>> > > > -       if (read_id == READING_FIRMWARE)
>> > > > +       switch (read_id) {
>> > > > +       case READING_FIRMWARE:
>> > > >                 func = FIRMWARE_CHECK;
>> > > > -       else if (read_id == READING_MODULE)
>> > > > +               break;
>> > > > +       case READING_MODULE:
>> > > >                 func = MODULE_CHECK;
>> > > > +               break;
>> > > > +       case READING_KEXEC_IMAGE:
>> > > > +               func = KEXEC_CHECK;
>> > > > +               break;
>> > > > +       case READING_KEXEC_INITRAMFS:
>> > > > +               func = INITRAMFS_CHECK;
>> > > > +               break;
>> > > > +       default:
>> > > > +               func = FILE_CHECK;
>> > > > +               break;
>> > > > +       }
>> > > >
>> > >
>> > > I would define a separate function like "int ima_read_id_to_func(id)"
>> > > which search over the map
>> > >
>> > > Something like...
>> > >
>> > > struct
>> > > {
>> > >      int id;
>> > >      int func;
>> > > }  map[] = {
>> > >   { .id = READING_FIRMWARE, .fun = FIRMWARE_CHECK },
>> > >    ...
>> > >   { -1, 0 }
>> > > };
>> > >
>> >
>> > So we stay with the duplication (option 1), but clean it up.  That works
>> > for me.
>> >
>>
>> Actually it may be simpler.
>> Just define int idmap[MAX_ID] and assign to every id corresponding func.
>> It will be quick and simple.
>
> Unlike the ima_read_id_to_func() above or the original switch/case
> statement, this method assumes the kernel_read_file_id enumeration stays
> in sync with ima_hooks.

Actually not necessary. You can use array initialization by index,
then you do not need to worry about sync...

static int idmap[] = {
         [READING_FIRMWARE] = FIRMWARE_CHECK,
         [READING_MODULE] = MODULE_CHECK,
         ...
};

> In terms of the  ima_read_id_to_func()
> function, it would iterate over the map[] to find the corresponding .id,
> whereas the current switch/case is a direct lookup.
>

switch is also iteration.

Dmitry
Actually

> Perhaps we should defer making a change for now.
>
> Mimi
>



-- 
Thanks,
Dmitry

  reply index

Thread overview: 77+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-02-03 19:06 [PATCH v3 00/22] vfs: support for a common kernel file loader Mimi Zohar
2016-02-03 19:06 ` [PATCH v3 01/22] ima: separate 'security.ima' reading functionality from collect Mimi Zohar
2016-02-03 19:06 ` [PATCH v3 02/22] ima: refactor ima_policy_show() to display "ima_hooks" rules Mimi Zohar
2016-02-07 19:45   ` Petko Manolov
2016-02-10 19:33   ` Dmitry Kasatkin
2016-02-03 19:06 ` [PATCH v3 03/22] ima: use "ima_hooks" enum as function argument Mimi Zohar
2016-02-07 19:46   ` Petko Manolov
2016-02-10 19:35   ` Dmitry Kasatkin
2016-02-03 19:06 ` [PATCH v3 04/22] firmware: simplify dev_*() print messages for generic helpers Mimi Zohar
2016-02-04 17:26   ` Kees Cook
2016-02-03 19:06 ` [PATCH v3 05/22] firmware: move completing fw into a helper Mimi Zohar
2016-02-04 17:27   ` Kees Cook
2016-02-03 19:06 ` [PATCH v3 06/22] firmware: fold successful fw read early Mimi Zohar
2016-02-04 17:36   ` Kees Cook
2016-02-04 20:26     ` Luis R. Rodriguez
2016-02-03 19:06 ` [PATCH v3 07/22] vfs: define a generic function to read a file from the kernel Mimi Zohar
2016-02-04 17:41   ` Kees Cook
2016-02-03 19:06 ` [PATCH v3 08/22] vfs: define kernel_read_file_id enumeration Mimi Zohar
2016-02-04 17:41   ` Kees Cook
2016-02-04 19:45   ` Luis R. Rodriguez
2016-02-03 19:06 ` [PATCH v3 09/22] ima: provide buffer hash calculation function Mimi Zohar
2016-02-03 19:06 ` [PATCH v3 10/22] ima: calculate the hash of a buffer using aynchronous hash(ahash) Mimi Zohar
2016-02-10 19:58   ` Dmitry Kasatkin
2016-02-03 19:06 ` [PATCH v3 11/22] ima: define a new hook to measure and appraise a file already in memory Mimi Zohar
2016-02-10 20:27   ` Dmitry Kasatkin
2016-02-03 19:06 ` [PATCH v3 12/22] vfs: define kernel_read_file_from_path Mimi Zohar
2016-02-04 17:46   ` Kees Cook
2016-02-04 19:47   ` Luis R. Rodriguez
2016-02-03 19:06 ` [PATCH v3 13/22] firmware: replace call to fw_read_file_contents() with kernel version Mimi Zohar
2016-02-04 17:56   ` Kees Cook
2016-02-04 19:51   ` Luis R. Rodriguez
2016-02-03 19:06 ` [PATCH v3 14/22] security: define kernel_read_file hook Mimi Zohar
2016-02-04 17:57   ` Kees Cook
2016-02-04 19:54   ` Luis R. Rodriguez
2016-02-11 16:54   ` Casey Schaufler
2016-02-11 19:35     ` Mimi Zohar
2016-02-03 19:06 ` [PATCH v3 15/22] vfs: define kernel_copy_file_from_fd() Mimi Zohar
2016-02-04 17:58   ` Kees Cook
2016-02-04 19:55   ` Luis R. Rodriguez
2016-02-03 19:06 ` [PATCH v3 16/22] module: replace copy_module_from_fd with kernel version Mimi Zohar
2016-02-04 18:04   ` Kees Cook
2016-02-04 19:56   ` Luis R. Rodriguez
2016-02-05  0:19     ` Mimi Zohar
2016-02-03 19:06 ` [PATCH v3 17/22] ima: remove firmware and module specific cached status info Mimi Zohar
2016-02-07 19:56   ` Petko Manolov
2016-02-10 20:18   ` Dmitry Kasatkin
2016-02-10 23:14     ` Mimi Zohar
2016-02-03 19:06 ` [PATCH v3 18/22] kexec: replace call to copy_file_from_fd() with kernel version Mimi Zohar
2016-02-04 18:05   ` Kees Cook
2016-02-04 19:57   ` Luis R. Rodriguez
2016-02-12 12:50   ` Dave Young
2016-02-03 19:06 ` [PATCH v3 19/22] ima: support for kexec image and initramfs Mimi Zohar
2016-02-07 20:10   ` Petko Manolov
2016-02-08 23:34     ` Mimi Zohar
2016-02-10 21:09   ` Dmitry Kasatkin
2016-02-10 23:21     ` Mimi Zohar
     [not found]       ` <CACE9dm8OJ1cgbKszUG-pCiEMVarUFLLWi_jewVV-JEMGAJsA-g@mail.gmail.com>
2016-02-11  2:08         ` Mimi Zohar
2016-02-11  8:47           ` Dmitry Kasatkin [this message]
2016-02-11 12:16             ` Mimi Zohar
2016-02-12 12:53   ` Dave Young
2016-02-12 13:09     ` Mimi Zohar
2016-02-03 19:06 ` [PATCH v3 20/22] ima: load policy using path Mimi Zohar
2016-02-07 19:59   ` Petko Manolov
2016-02-08  9:58     ` Dmitry Kasatkin
2016-02-08 10:35       ` Petko Manolov
2016-02-08 10:45         ` Dmitry Kasatkin
2016-02-08 21:12           ` Mimi Zohar
2016-02-09  7:47             ` Petko Manolov
2016-02-03 19:06 ` [PATCH v3 21/22] ima: measure and appraise the IMA policy itself Mimi Zohar
2016-02-07 20:01   ` Petko Manolov
2016-02-10 20:22   ` Dmitry Kasatkin
2016-02-10 23:15     ` Mimi Zohar
2016-02-03 19:06 ` [PATCH v3 22/22] ima: require signed IMA policy Mimi Zohar
2016-02-07 20:02   ` Petko Manolov
2016-02-10 20:24   ` Dmitry Kasatkin
2016-02-04 18:15 ` [PATCH v3 00/22] vfs: support for a common kernel file loader Kees Cook
2016-02-04 23:54   ` Mimi Zohar

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