linux-kernel - Re: [PATCH 2/2] ima: Support appraise_type=imasig

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CALLzPKaHLSg0TromnTvpEVroBUtPJE3TwF4RmcA2dtkuB5H4hQ@mail.gmail.com>
Date:	Wed, 13 Feb 2013 15:13:30 +0200
From:	"Kasatkin, Dmitry" <dmitry.kasatkin@...el.com>
To:	Mimi Zohar <zohar@...ux.vnet.ibm.com>
Cc:	Vivek Goyal <vgoyal@...hat.com>,
	linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] ima: Support appraise_type=imasig_optional

On Wed, Feb 13, 2013 at 2:56 PM, Mimi Zohar <zohar@...ux.vnet.ibm.com> wrote:
> On Wed, 2013-02-13 at 14:31 +0200, Kasatkin, Dmitry wrote:
>> On Mon, Feb 11, 2013 at 10:11 PM, Vivek Goyal <vgoyal@...hat.com> wrote:
>
>> > @@ -158,7 +165,8 @@ int ima_appraise_measurement(int func, struct integrity_iint_cache *iint,
>> >         }
>> >         switch (xattr_value->type) {
>> >         case IMA_XATTR_DIGEST:
>> > -               if (iint->flags & IMA_DIGSIG_REQUIRED) {
>> > +               if (iint->flags & IMA_DIGSIG_REQUIRED ||
>> > +                   iint->flags & IMA_DIGSIG_OPTIONAL) {
>> >                         cause = "IMA signature required";
>> >                         status = INTEGRITY_FAIL;
>> >                         break;
>>
>> This looks a bit odd... If "optional" signature is missing  - we fail..
>> It is optional... Why we should fail?
>
> 'imasig_optional' does not only mean that the signature is optional, but
> also implies that it has to be a digital signature, not a hash.  This
> latter part is what IMA_DIGSIG_REQUIRED means.
>
> If 'imasig_optional' set both 'IMA_DIGSIG_OPTIONAL' and
> 'IMA_DIGSIG_REQUIRED', then this change wouldn't be necessary.
>
> IMA_DIGSIG_REQUIRED would enforce that it is a signature.
> IMA_DIGSIG_OPTIONAL would fail only for files with invalid signatures.
>

It sounds odd that optional signature is actually required.
Optional for me means that it may be there or may be not.
If it is not there, then it may be hash or nothing.

I see it is more logical if it is "appraise_type=optional",
which means that we might have no xattr value, hash or signature.
It if happens to be a signature, then IMA_DIGSIG flag will be set.

I asked Vivek to send a policy file he uses in his system.
I would like to see how system configured as a whole...

- Dmitry

> thanks,
>
> Mimi
>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/