From: Zhen Lei Date: Thu, 12 Jul 2018 09:28:43 +0000 (+0800) Subject: iommu/arm-smmu-v3: Prevent any devices access to memory without registration X-Git-Tag: v4.19-rc1~21^2^4^2~1 X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=a71792dee2a33d2e935d4b67dd63924f5ceb203d;p=linux.git iommu/arm-smmu-v3: Prevent any devices access to memory without registration 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 Signed-off-by: Will Deacon --- diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c index deacc152f09f..7fb5230cd145 100644 --- a/drivers/iommu/arm-smmu-v3.c +++ b/drivers/iommu/arm-smmu-v3.c @@ -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.");