From: Greg KH <gregkh@linuxfoundation.org>
To: Roberto Sassu <roberto.sassu@huawei.com>
Cc: "zohar@linux.ibm.com" <zohar@linux.ibm.com>,
"linux-integrity@vger.kernel.org"
<linux-integrity@vger.kernel.org>,
"linux-security-module@vger.kernel.org"
<linux-security-module@vger.kernel.org>,
"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
"linux-kselftest@vger.kernel.org"
<linux-kselftest@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [RFC][PATCH 03/12] digest_lists: Basic definitions
Date: Mon, 28 Jun 2021 11:32:18 +0200 [thread overview]
Message-ID: <YNmXIk7orQavkEME@kroah.com> (raw)
In-Reply-To: <4acc7e8f15834b83b310b9e2ff9ba3d2@huawei.com>
On Mon, Jun 28, 2021 at 09:27:05AM +0000, Roberto Sassu wrote:
> > From: Greg KH [mailto:gregkh@linuxfoundation.org]
> > Sent: Monday, June 28, 2021 10:46 AM
> > On Mon, Jun 28, 2021 at 08:30:32AM +0000, Roberto Sassu wrote:
> > > > > +struct compact_list_hdr {
> > > > > + __u8 version;
> > > >
> > > > You should never need a version, that way lies madness.
> > >
> > > We wanted to have a way to switch to a new format, if necessary.
> >
> > Then just add a new ioctl if you need that in the future, no need to try
> > to cram it into this one.
>
> Given that digest lists are generated elsewhere, it would be still
> unclear when the ioctl() would be issued. Maybe the kernel needs
> to parse both v1 and v2 digest lists (I expect that v1 cannot be easily
> converted to v2, if they are signed).
>
> It would be also unpractical if digest lists are loaded at kernel
> initialization time (I didn't send the patch yet).
Then that is up to your api design, I do not know. But note that
"version" fields almost always never work, so be careful about assuming
that this will solve any future issues.
> > > > > + __le16 type;
> > > > > + __le16 modifiers;
> > > > > + __le16 algo;
> > > > > + __le32 count;
> > > > > + __le32 datalen;
> > > >
> > > > Why are user/kernel apis specified in little endian format? Why would
> > > > that matter? Shouldn't they just be "native" endian?
> > >
> > > I thought this would make it clear that the kernel always expects the
> > > digest lists to be in little endian.
> >
> > Why would a big endian system expect the data from userspace to be in
> > little endian? Shouldn't this always just be "native" endian given that
> > this is not something that is being sent to hardware?
>
> The digest list might come from a system with different endianness.
Ok, I have no idea what digests really are used for then. So stick with
little endian and be sure to properly convert within the kernel as
needed.
thanks,
greg k-h
next prev parent reply other threads:[~2021-06-28 9:32 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-25 16:56 [RFC][PATCH 00/12] Huawei Digest Lists Roberto Sassu
2021-06-25 16:56 ` [RFC][PATCH 01/12] ima: Add digest, algo, measured parameters to ima_measure_critical_data() Roberto Sassu
2021-06-25 18:26 ` Mimi Zohar
2021-06-25 16:56 ` [RFC][PATCH 02/12] digest_lists: Overview Roberto Sassu
2021-06-25 16:56 ` [RFC][PATCH 03/12] digest_lists: Basic definitions Roberto Sassu
2021-06-27 10:53 ` Greg KH
2021-06-27 15:23 ` Matthew Wilcox
2021-06-27 15:35 ` Greg KH
2021-06-28 8:30 ` Roberto Sassu
2021-06-28 8:46 ` Greg KH
2021-06-28 9:27 ` Roberto Sassu
2021-06-28 9:32 ` Greg KH [this message]
2021-06-28 9:51 ` Roberto Sassu
2021-06-25 16:56 ` [RFC][PATCH 04/12] digest_lists: Objects Roberto Sassu
2021-06-27 10:56 ` Greg KH
2021-06-28 8:14 ` Roberto Sassu
2021-06-28 8:47 ` Greg KH
2021-06-25 16:56 ` [RFC][PATCH 05/12] digest_lists: Methods Roberto Sassu
2021-06-25 16:56 ` [RFC][PATCH 06/12] digest_lists: Parser Roberto Sassu
2021-06-25 16:56 ` [RFC][PATCH 07/12] digest_lists: Interfaces - digest_list_add, digest_list_del Roberto Sassu
2021-06-25 16:56 ` [RFC][PATCH 08/12] digest_lists: Interfaces - digest_lists_loaded Roberto Sassu
2021-06-25 16:56 ` [RFC][PATCH 09/12] digest_lists: Interfaces - digest_label Roberto Sassu
2021-06-25 16:56 ` [RFC][PATCH 10/12] digest_lists: Interfaces - digest_query Roberto Sassu
2021-06-25 16:56 ` [RFC][PATCH 11/12] digest_lists: Interfaces - digests_count Roberto Sassu
2021-06-25 16:56 ` [RFC][PATCH 12/12] digest_lists: Tests Roberto Sassu
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