linux-kernel - Re: [PATCH v6 1/5] iommu: Return -EMEDIUMTYPE for incompatible domain and device/group

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]

Date:   Mon, 12 Sep 2022 22:07:37 -0700
From:   Nicolin Chen <nicolinc@...dia.com>
To:     "Tian, Kevin" <kevin.tian@...el.com>
CC:     Jason Gunthorpe <jgg@...dia.com>, Joerg Roedel <joro@...tes.org>,
        "will@...nel.org" <will@...nel.org>,
        "robin.murphy@....com" <robin.murphy@....com>,
        "alex.williamson@...hat.com" <alex.williamson@...hat.com>,
        "suravee.suthikulpanit@....com" <suravee.suthikulpanit@....com>,
        "marcan@...can.st" <marcan@...can.st>,
        "sven@...npeter.dev" <sven@...npeter.dev>,
        "alyssa@...enzweig.io" <alyssa@...enzweig.io>,
        "robdclark@...il.com" <robdclark@...il.com>,
        "dwmw2@...radead.org" <dwmw2@...radead.org>,
        "baolu.lu@...ux.intel.com" <baolu.lu@...ux.intel.com>,
        "mjrosato@...ux.ibm.com" <mjrosato@...ux.ibm.com>,
        "gerald.schaefer@...ux.ibm.com" <gerald.schaefer@...ux.ibm.com>,
        "orsonzhai@...il.com" <orsonzhai@...il.com>,
        "baolin.wang@...ux.alibaba.com" <baolin.wang@...ux.alibaba.com>,
        "zhang.lyra@...il.com" <zhang.lyra@...il.com>,
        "thierry.reding@...il.com" <thierry.reding@...il.com>,
        "vdumpa@...dia.com" <vdumpa@...dia.com>,
        "jonathanh@...dia.com" <jonathanh@...dia.com>,
        "jean-philippe@...aro.org" <jean-philippe@...aro.org>,
        "cohuck@...hat.com" <cohuck@...hat.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "shameerali.kolothum.thodi@...wei.com" 
        <shameerali.kolothum.thodi@...wei.com>,
        "thunder.leizhen@...wei.com" <thunder.leizhen@...wei.com>,
        "christophe.jaillet@...adoo.fr" <christophe.jaillet@...adoo.fr>,
        "yangyingliang@...wei.com" <yangyingliang@...wei.com>,
        "jon@...id-run.com" <jon@...id-run.com>,
        "iommu@...ts.linux.dev" <iommu@...ts.linux.dev>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "asahi@...ts.linux.dev" <asahi@...ts.linux.dev>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-arm-msm@...r.kernel.org" <linux-arm-msm@...r.kernel.org>,
        "linux-s390@...r.kernel.org" <linux-s390@...r.kernel.org>,
        "linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
        "virtualization@...ts.linux-foundation.org" 
        <virtualization@...ts.linux-foundation.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>
Subject: Re: [PATCH v6 1/5] iommu: Return -EMEDIUMTYPE for incompatible
 domain and device/group

On Tue, Sep 13, 2022 at 02:22:17AM +0000, Tian, Kevin wrote:
> External email: Use caution opening links or attachments
> 
> 
> > From: Jason Gunthorpe <jgg@...dia.com>
> > Sent: Friday, September 9, 2022 8:08 PM
> >
> >
> > > As discussed in a side thread a note might be added to exempt calling
> > > kAPI outside of the iommu driver.
> >
> > Sadly, not really.. The driver is responsible to santize this if it is
> > relevant. It is the main downside of this approach.
> >
> 
> Better provide a clarification on what sanitization means.
> 
> e.g. I don't think we should change errno in those kAPIs to match the
> definition in iommu subsystem since e.g. -EINVAL really means different
> things in different context.
> 
> So the sanitization in iommu driver is probably that:
> 
>   - If an external kAPI returns -EINVAL, convert it to -ENODEV given iommu
>     domain is iommu internal object hence unlikely for external kAPIs to
>     capture incompatibility issue between domain/device;
>   - Otherwise just pass whatever returned to the caller, following the definition
>     of "Same behavior as -ENODEV" above

I added something similar. Thanks!

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index ea30f00dc145..190647d018f9 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -266,6 +266,17 @@ struct iommu_ops {
 /**
  * struct iommu_domain_ops - domain specific operations
  * @attach_dev: attach an iommu domain to a device
+ *              Rules of its return errno:
+ *               EINVAL  - Exclusively, device and domain are incompatible. Must
+ *                         avoid kernel prints along with this errno. An EINVAL
+ *                         returned from a kAPI must be coverted to ENODEV if it
+ *                         is device specific, or to some other reasonable errno
+ *                         being listed below
+ *               ENOMEM  - Out of memory
+ *               ENOSPC  - No space left on device
+ *               EBUSY   - Device is attached to a domain and cannot be changed
+ *               ENODEV  - Device specific errors, not able to be attached
+ *              <others> - Treated as ENODEV by the caller. Use is discouraged
  * @detach_dev: detach an iommu domain from a device
  * @map: map a physically contiguous memory region to an iommu domain
  * @map_pages: map a physically contiguous set of pages of the same size to