linux-kernel - [RESEND PATCH] iommu/intel: Exclude devices using RMRRs from IOMMU API domains

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-next>] [day] [month] [year] [list]

Date:	Thu, 12 Jun 2014 10:35:23 -0600
From:	Alex Williamson <alex.williamson@...hat.com>
To:	iommu@...ts.linux-foundation.org, dwmw2@...radead.org
Cc:	chegu_vinod@...com, linux-kernel@...r.kernel.org
Subject: [RESEND PATCH] iommu/intel: Exclude devices using RMRRs from IOMMU
 API domains

The user of the IOMMU API domain expects to have full control of
the IOVA space for the domain.  RMRRs are fundamentally incompatible
with that idea.  We can neither map the RMRR into the IOMMU API
domain, nor can we guarantee that the device won't continue DMA with
the area described by the RMRR as part of the new domain.  Therefore
we must prevent such devices from being used by the IOMMU API.

Signed-off-by: Alex Williamson <alex.williamson@...hat.com>
---

I didn't see any actionable items from the last posting of this, so
re-posting unchanged.

 drivers/iommu/intel-iommu.c |   15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index c4f11c0..41db805 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -4171,6 +4171,21 @@ static int intel_iommu_attach_device(struct iommu_domain *domain,
 	int addr_width;
 	u8 bus, devfn;
 
+	/*
+	 * With IOMMU API domains we don't have the freedom to insert RMRR
+	 * entries into the domain mapping, the IOMMU API user expects full
+	 * control of the IOVA space of the device.  We also have no ability
+	 * to shutdown whatever back channel operations occur through the
+	 * RMRR.  Therefore our only option is to prevent devices making use
+	 * of RMRRs from being used by the IOMMU API.  As usual we exempt
+	 * USB devices since their RMRR support is largely historical.
+	 */
+	if (device_has_rmrr(dev) && (!dev_is_pci(dev) ||
+	    (to_pci_dev(dev)->class >> 8) != PCI_CLASS_SERIAL_USB)) {
+		dev_warn(dev, "Device is ineligible for IOMMU domain attach due to platform RMRR requirement.  Contact your platform vendor.\n");
+		return -EPERM;
+	}
+
 	/* normally dev is not mapped */
 	if (unlikely(domain_context_mapped(dev))) {
 		struct dmar_domain *old_domain;

--
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/