Android folks, poke below. otherwise we'll have no option but to seriously consider Mimi's patch to prevent these calls when IMA appraisal is enforced: http://lkml.kernel.org/r/1525182503-13849-7-git-send-email-zohar@xxxxxxxxxxxxxxxxxx Please read below.... On Wed, Apr 25, 2018 at 05:55:57PM +0000, Luis R. Rodriguez wrote: > On Wed, Apr 25, 2018 at 01:00:09AM -0400, Mimi Zohar wrote: > > On Tue, 2018-04-24 at 23:42 +0000, Luis R. Rodriguez wrote: > > > On Tue, Apr 24, 2018 at 12:07:01PM -0400, Mimi Zohar wrote: > > > > On Tue, 2018-04-24 at 17:09 +0200, Hans de Goede wrote: > > > If its of any help -- > > > > > > drivers/soc/qcom/mdt_loader.c is the only driver currently using > > > request_firmware_into_buf() however I'll note qcom_mdt_load() is used in many > > > other drivers so they are wrappers around request_firmware_into_buf(): > > > > > > drivers/gpu/drm/msm/adreno/a5xx_gpu.c: * adreno_request_fw() handles this, but qcom_mdt_load() does > > > drivers/gpu/drm/msm/adreno/a5xx_gpu.c: ret = qcom_mdt_load(dev, fw, fwname, GPU_PAS_ID, > > > drivers/gpu/drm/msm/adreno/a5xx_gpu.c: ret = qcom_mdt_load(dev, fw, newname, GPU_PAS_ID, > > > drivers/media/platform/qcom/venus/firmware.c: ret = qcom_mdt_load(dev, mdt, fwname, VENUS_PAS_ID, mem_va, mem_phys, > > > drivers/remoteproc/qcom_adsp_pil.c: return qcom_mdt_load(adsp->dev, fw, rproc->firmware, adsp->pas_id, > > > drivers/remoteproc/qcom_wcnss.c: return qcom_mdt_load(wcnss->dev, fw, rproc->firmware, WCNSS_PAS_ID, > > > > > > > > As such the current IMA code (from v4.17-rc2) actually does > > > > > not handle READING_FIRMWARE_PREALLOC_BUFFER at all, > > > > > > > > Right, it doesn't yet address READING_FIRMWARE_PREALLOC_BUFFER, but > > > > should. > > > > > > > > Depending on whether the device requesting the firmware has access to > > > > the DMA memory, before the signature verification, > > > > > > It would seem from the original patch review about READING_FIRMWARE_PREALLOC_BUFFER > > > that this is not a DMA buffer. To be very clear I believe Stephen implied this was not DMA buffer. Mimi asked for READING_FIRMWARE_DMA if it was: https://patchwork.kernel.org/patch/9074611/ > > The call sequence: > > qcom_mdt_load() -> qcom_scm_pas_init_image() -> dma_alloc_coherent() > > > > If dma_alloc_coherent() isn't allocating a DMA buffer, then the > > function name is misleading/confusing. > > Hah, by *definition* the device *and* processor has immediate access > to data written *immediately* when dma_alloc_coherent() is used. From > Documentation/DMA-API.txt: > > ----------------------------------------------------------------------- > Part Ia - Using large DMA-coherent buffers > ------------------------------------------ > > :: > > void * > dma_alloc_coherent(struct device *dev, size_t size, > dma_addr_t *dma_handle, gfp_t flag) > > Consistent memory is memory for which a write by either the device or > the processor can immediately be read by the processor or device > without having to worry about caching effects. (You may however need > to make sure to flush the processor's write buffers before telling > devices to read that memory.) > ------------------------------------------------------------------------ > > Is ptr below > > ret = request_firmware_into_buf(&seg_fw, fw_name, dev, > ptr, phdr->p_filesz); > > Also part of the DMA buffer allocated earlier via: > > ret = qcom_scm_pas_init_image(pas_id, fw->data, fw->size); > > Android folks? Android folks? > > > The device driver should have access to the buffer pointer with write given > > > that with request_firmware_into_buf() the driver is giving full write access to > > > the memory pointer so that the firmware API can stuff the firmware it finds > > > there. > > > > > > Firmware signature verification would be up to the device hardware to do upon > > > load *after* request_firmware_into_buf(). > > > > We're discussing the kernel's signature verification, not the device > > hardware's signature verification. Can the device driver access the > > buffer, before IMA-appraisal has verified the firmware's signature? > > It will depend on the above question. Luis -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
