linux/drivers/base/firmware_loader/fallback_platform.c

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firmware: Add new platform fallback mechanism and firmware_request_platform() In some cases the platform's main firmware (e.g. the UEFI fw) may contain an embedded copy of device firmware which needs to be (re)loaded into the peripheral. Normally such firmware would be part of linux-firmware, but in some cases this is not feasible, for 2 reasons: 1) The firmware is customized for a specific use-case of the chipset / use with a specific hardware model, so we cannot have a single firmware file for the chipset. E.g. touchscreen controller firmwares are compiled specifically for the hardware model they are used with, as they are calibrated for a specific model digitizer. 2) Despite repeated attempts we have failed to get permission to redistribute the firmware. This is especially a problem with customized firmwares, these get created by the chip vendor for a specific ODM and the copyright may partially belong with the ODM, so the chip vendor cannot give a blanket permission to distribute these. This commit adds a new platform fallback mechanism to the firmware loader which will try to lookup a device fw copy embedded in the platform's main firmware if direct filesystem lookup fails. Drivers which need such embedded fw copies can enable this fallback mechanism by using the new firmware_request_platform() function. Note that for now this is only supported on EFI platforms and even on these platforms firmware_fallback_platform() only works if CONFIG_EFI_EMBEDDED_FIRMWARE is enabled (this gets selected by drivers which need this), in all other cases firmware_fallback_platform() simply always returns -ENOENT. Reported-by: Dave Olsthoorn <dave@bewaar.me> Suggested-by: Peter Jones <pjones@redhat.com> Acked-by: Luis Chamberlain <mcgrof@kernel.org> Signed-off-by: Hans de Goede <hdegoede@redhat.com> Link: https://lore.kernel.org/r/20200115163554.101315-5-hdegoede@redhat.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-01-15 17:35:48 +01:00
// SPDX-License-Identifier: GPL-2.0
#include <linux/efi_embedded_fw.h>
#include <linux/property.h>
#include <linux/security.h>
#include <linux/vmalloc.h>
#include "fallback.h"
#include "firmware.h"
int firmware_fallback_platform(struct fw_priv *fw_priv, u32 opt_flags)
firmware: Add new platform fallback mechanism and firmware_request_platform() In some cases the platform's main firmware (e.g. the UEFI fw) may contain an embedded copy of device firmware which needs to be (re)loaded into the peripheral. Normally such firmware would be part of linux-firmware, but in some cases this is not feasible, for 2 reasons: 1) The firmware is customized for a specific use-case of the chipset / use with a specific hardware model, so we cannot have a single firmware file for the chipset. E.g. touchscreen controller firmwares are compiled specifically for the hardware model they are used with, as they are calibrated for a specific model digitizer. 2) Despite repeated attempts we have failed to get permission to redistribute the firmware. This is especially a problem with customized firmwares, these get created by the chip vendor for a specific ODM and the copyright may partially belong with the ODM, so the chip vendor cannot give a blanket permission to distribute these. This commit adds a new platform fallback mechanism to the firmware loader which will try to lookup a device fw copy embedded in the platform's main firmware if direct filesystem lookup fails. Drivers which need such embedded fw copies can enable this fallback mechanism by using the new firmware_request_platform() function. Note that for now this is only supported on EFI platforms and even on these platforms firmware_fallback_platform() only works if CONFIG_EFI_EMBEDDED_FIRMWARE is enabled (this gets selected by drivers which need this), in all other cases firmware_fallback_platform() simply always returns -ENOENT. Reported-by: Dave Olsthoorn <dave@bewaar.me> Suggested-by: Peter Jones <pjones@redhat.com> Acked-by: Luis Chamberlain <mcgrof@kernel.org> Signed-off-by: Hans de Goede <hdegoede@redhat.com> Link: https://lore.kernel.org/r/20200115163554.101315-5-hdegoede@redhat.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-01-15 17:35:48 +01:00
{
const u8 *data;
size_t size;
int rc;
if (!(opt_flags & FW_OPT_FALLBACK_PLATFORM))
return -ENOENT;
LSM: Introduce kernel_post_load_data() hook There are a few places in the kernel where LSMs would like to have visibility into the contents of a kernel buffer that has been loaded or read. While security_kernel_post_read_file() (which includes the buffer) exists as a pairing for security_kernel_read_file(), no such hook exists to pair with security_kernel_load_data(). Earlier proposals for just using security_kernel_post_read_file() with a NULL file argument were rejected (i.e. "file" should always be valid for the security_..._file hooks, but it appears at least one case was left in the kernel during earlier refactoring. (This will be fixed in a subsequent patch.) Since not all cases of security_kernel_load_data() can have a single contiguous buffer made available to the LSM hook (e.g. kexec image segments are separately loaded), there needs to be a way for the LSM to reason about its expectations of the hook coverage. In order to handle this, add a "contents" argument to the "kernel_load_data" hook that indicates if the newly added "kernel_post_load_data" hook will be called with the full contents once loaded. That way, LSMs requiring full contents can choose to unilaterally reject "kernel_load_data" with contents=false (which is effectively the existing hook coverage), but when contents=true they can allow it and later evaluate the "kernel_post_load_data" hook once the buffer is loaded. With this change, LSMs can gain coverage over non-file-backed data loads (e.g. init_module(2) and firmware userspace helper), which will happen in subsequent patches. Additionally prepare IMA to start processing these cases. Signed-off-by: Kees Cook <keescook@chromium.org> Reviewed-by: KP Singh <kpsingh@google.com> Link: https://lore.kernel.org/r/20201002173828.2099543-9-keescook@chromium.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-10-02 10:38:20 -07:00
rc = security_kernel_load_data(LOADING_FIRMWARE, false);
firmware: Add new platform fallback mechanism and firmware_request_platform() In some cases the platform's main firmware (e.g. the UEFI fw) may contain an embedded copy of device firmware which needs to be (re)loaded into the peripheral. Normally such firmware would be part of linux-firmware, but in some cases this is not feasible, for 2 reasons: 1) The firmware is customized for a specific use-case of the chipset / use with a specific hardware model, so we cannot have a single firmware file for the chipset. E.g. touchscreen controller firmwares are compiled specifically for the hardware model they are used with, as they are calibrated for a specific model digitizer. 2) Despite repeated attempts we have failed to get permission to redistribute the firmware. This is especially a problem with customized firmwares, these get created by the chip vendor for a specific ODM and the copyright may partially belong with the ODM, so the chip vendor cannot give a blanket permission to distribute these. This commit adds a new platform fallback mechanism to the firmware loader which will try to lookup a device fw copy embedded in the platform's main firmware if direct filesystem lookup fails. Drivers which need such embedded fw copies can enable this fallback mechanism by using the new firmware_request_platform() function. Note that for now this is only supported on EFI platforms and even on these platforms firmware_fallback_platform() only works if CONFIG_EFI_EMBEDDED_FIRMWARE is enabled (this gets selected by drivers which need this), in all other cases firmware_fallback_platform() simply always returns -ENOENT. Reported-by: Dave Olsthoorn <dave@bewaar.me> Suggested-by: Peter Jones <pjones@redhat.com> Acked-by: Luis Chamberlain <mcgrof@kernel.org> Signed-off-by: Hans de Goede <hdegoede@redhat.com> Link: https://lore.kernel.org/r/20200115163554.101315-5-hdegoede@redhat.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-01-15 17:35:48 +01:00
if (rc)
return rc;
rc = efi_get_embedded_fw(fw_priv->fw_name, &data, &size);
if (rc)
return rc; /* rc == -ENOENT when the fw was not found */
if (fw_priv->data && size > fw_priv->allocated_size)
return -ENOMEM;
if (!fw_priv->data)
fw_priv->data = vmalloc(size);
firmware: Add new platform fallback mechanism and firmware_request_platform() In some cases the platform's main firmware (e.g. the UEFI fw) may contain an embedded copy of device firmware which needs to be (re)loaded into the peripheral. Normally such firmware would be part of linux-firmware, but in some cases this is not feasible, for 2 reasons: 1) The firmware is customized for a specific use-case of the chipset / use with a specific hardware model, so we cannot have a single firmware file for the chipset. E.g. touchscreen controller firmwares are compiled specifically for the hardware model they are used with, as they are calibrated for a specific model digitizer. 2) Despite repeated attempts we have failed to get permission to redistribute the firmware. This is especially a problem with customized firmwares, these get created by the chip vendor for a specific ODM and the copyright may partially belong with the ODM, so the chip vendor cannot give a blanket permission to distribute these. This commit adds a new platform fallback mechanism to the firmware loader which will try to lookup a device fw copy embedded in the platform's main firmware if direct filesystem lookup fails. Drivers which need such embedded fw copies can enable this fallback mechanism by using the new firmware_request_platform() function. Note that for now this is only supported on EFI platforms and even on these platforms firmware_fallback_platform() only works if CONFIG_EFI_EMBEDDED_FIRMWARE is enabled (this gets selected by drivers which need this), in all other cases firmware_fallback_platform() simply always returns -ENOENT. Reported-by: Dave Olsthoorn <dave@bewaar.me> Suggested-by: Peter Jones <pjones@redhat.com> Acked-by: Luis Chamberlain <mcgrof@kernel.org> Signed-off-by: Hans de Goede <hdegoede@redhat.com> Link: https://lore.kernel.org/r/20200115163554.101315-5-hdegoede@redhat.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-01-15 17:35:48 +01:00
if (!fw_priv->data)
return -ENOMEM;
memcpy(fw_priv->data, data, size);
fw_priv->size = size;
fw_state_done(fw_priv);
return 0;
}