linux-kernel - Re: [PATCH v3 1/4] iommu/vt-d: Implement domain ops for attach_dev

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: <20220510232121.GP49344@nvidia.com>
Date:   Tue, 10 May 2022 20:21:21 -0300
From:   Jason Gunthorpe <jgg@...dia.com>
To:     Jacob Pan <jacob.jun.pan@...ux.intel.com>
Cc:     iommu@...ts.linux-foundation.org,
        LKML <linux-kernel@...r.kernel.org>, dmaengine@...r.kernel.org,
        Joerg Roedel <joro@...tes.org>,
        David Woodhouse <dwmw2@...radead.org>,
        Jean-Philippe Brucker <jean-philippe@...aro.com>,
        Lu Baolu <baolu.lu@...ux.intel.com>, vkoul@...nel.org,
        robin.murphy@....com, will@...nel.org, Yi Liu <yi.l.liu@...el.com>,
        Dave Jiang <dave.jiang@...el.com>,
        "Tian, Kevin" <kevin.tian@...el.com>,
        Raj Ashok <ashok.raj@...el.com>,
        Eric Auger <eric.auger@...hat.com>
Subject: Re: [PATCH v3 1/4] iommu/vt-d: Implement domain ops for
 attach_dev_pasid

On Tue, May 10, 2022 at 02:07:01PM -0700, Jacob Pan wrote:
> +static int intel_iommu_attach_dev_pasid(struct iommu_domain *domain,
> +					struct device *dev,
> +					ioasid_t pasid)
> +{
> +	struct device_domain_info *info = dev_iommu_priv_get(dev);
> +	struct dmar_domain *dmar_domain = to_dmar_domain(domain);
> +	struct intel_iommu *iommu = info->iommu;
> +	unsigned long flags;
> +	int ret = 0;
> +
> +	if (!sm_supported(iommu) || !info)
> +		return -ENODEV;
> +
> +	spin_lock_irqsave(&device_domain_lock, flags);
> +	/*
> +	 * If the same device already has a PASID attached, just return.
> +	 * DMA layer will return the PASID value to the caller.
> +	 */
> +	if (pasid != PASID_RID2PASID && info->pasid) {

Why check for PASID == 0 like this? Shouldn't pasid == 0 be rejected
as an invalid argument?

> +		if (info->pasid == pasid)
> +			ret = 0;

Doesn't this need to check that the current domain is the requested
domain as well? How can this happen anyhow - isn't it an error to
double attach?

> diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
> index 5af24befc9f1..55845a8c4f4d 100644
> +++ b/include/linux/intel-iommu.h
> @@ -627,6 +627,7 @@ struct device_domain_info {
>  	struct intel_iommu *iommu; /* IOMMU used by this device */
>  	struct dmar_domain *domain; /* pointer to domain */
>  	struct pasid_table *pasid_table; /* pasid table */
> +	ioasid_t pasid; /* DMA request with PASID */

And this seems wrong - the DMA API is not the only user of
attach_dev_pasid, so there should not be any global pasid for the
device.

I suspect this should be a counter of # of pasid domains attached so
that the special flush logic triggers

And rely on the core code to worry about assigning only one domain per
pasid - this should really be a 'set' function.

Jason