On Fri, Jun 25, 2021 at 3:20 AM Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> wrote: > > On Thu, Jun 24, 2021 at 11:55:14PM +0800, Claire Chang wrote: > > This series implements mitigations for lack of DMA access control on > > systems without an IOMMU, which could result in the DMA accessing the > > system memory at unexpected times and/or unexpected addresses, possibly > > leading to data leakage or corruption. > > > > For example, we plan to use the PCI-e bus for Wi-Fi and that PCI-e bus is > > not behind an IOMMU. As PCI-e, by design, gives the device full access to > > system memory, a vulnerability in the Wi-Fi firmware could easily escalate > > to a full system exploit (remote wifi exploits: [1a], [1b] that shows a > > full chain of exploits; [2], [3]). > > > > To mitigate the security concerns, we introduce restricted DMA. Restricted > > DMA utilizes the existing swiotlb to bounce streaming DMA in and out of a > > specially allocated region and does memory allocation from the same region. > > The feature on its own provides a basic level of protection against the DMA > > overwriting buffer contents at unexpected times. However, to protect > > against general data leakage and system memory corruption, the system needs > > to provide a way to restrict the DMA to a predefined memory region (this is > > usually done at firmware level, e.g. MPU in ATF on some ARM platforms [4]). > > > > [1a] https://googleprojectzero.blogspot.com/2017/04/over-air-exploiting-broadcoms-wi-fi_4.html > > [1b] https://googleprojectzero.blogspot.com/2017/04/over-air-exploiting-broadcoms-wi-fi_11.html > > [2] https://blade.tencent.com/en/advisories/qualpwn/ > > [3] https://www.bleepingcomputer.com/news/security/vulnerabilities-found-in-highly-popular-firmware-for-wifi-chips/ > > [4] https://github.com/ARM-software/arm-trusted-firmware/blob/master/plat/mediatek/mt8183/drivers/emi_mpu/emi_mpu.c#L132 > > > > v15: > > - Apply Will's diff (https://lore.kernel.org/patchwork/patch/1448957/#1647521) > > to fix the crash reported by Qian. > > - Add Stefano's Acked-by tag for patch 01/12 from v14 > > That all should be now be on > > https://git.kernel.org/pub/scm/linux/kernel/git/konrad/swiotlb.git/ > devel/for-linus-5.14 (and linux-next) > devel/for-linus-5.14 looks good. Thanks!
