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iommu/arm-smmu-v3: Prevent any devices access to memory without registration

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Stream bypass is a potential security hole since a malicious device can be
hotplugged in without matching any drivers, yet be granted the ability to
access all of physical memory.

Now that we attach devices to domains by default, we can toggle the
disable_bypass default to "on", preventing DMA from unknown devices.

Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Zhen Lei 2018-07-12 17:28:43 +08:00 committed by Will Deacon
parent 0d535967ac
commit a71792dee2
1 changed files with 1 additions and 1 deletions
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drivers/iommu/arm-smmu-v3.c
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@ -366,7 +366,7 @@
#define MSI_IOVA_BASE 0x8000000
#define MSI_IOVA_LENGTH 0x100000
static bool disable_bypass;
static bool disable_bypass = 1;
module_param_named(disable_bypass, disable_bypass, bool, S_IRUGO);
MODULE_PARM_DESC(disable_bypass,
"Disable bypass streams such that incoming transactions from devices that are not attached to an iommu domain will report an abort back to the device and will not be allowed to pass through the SMMU.");