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[94.66.201.28]) by smtp.gmail.com with ESMTPSA id n13sm659793wmd.21.2020.02.06.12.09.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 06 Feb 2020 12:09:42 -0800 (PST) Date: Thu, 6 Feb 2020 22:09:40 +0200 From: Ilias Apalodimas To: Heinrich Schuchardt Cc: Ard Biesheuvel , linux-efi@vger.kernel.org, linux-arm-kernel@lists.infradead.org, lersek@redhat.com, leif@nuviainc.com, pjones@redhat.com, mjg59@google.com, agraf@csgraf.de, daniel.kiper@oracle.com Subject: Re: [PATCH 1/2] efi/libstub: add support for loading the initrd from a device path Message-ID: <20200206200940.GA750064@apalos.home> References: <20200206140352.6300-1-ardb@kernel.org> <20200206140352.6300-2-ardb@kernel.org> <20200206184608.GA749195@apalos.home> <2ffcb05e-761a-9345-7da5-c08f5cda914e@gmx.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2ffcb05e-761a-9345-7da5-c08f5cda914e@gmx.de> Sender: linux-efi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org On Thu, Feb 06, 2020 at 08:15:11PM +0100, Heinrich Schuchardt wrote: > On 2/6/20 7:46 PM, Ilias Apalodimas wrote: > > Hi Heinrich, > > > > I actually like the approach. > > > > On Thu, Feb 06, 2020 at 07:26:20PM +0100, Heinrich Schuchardt wrote: > > [...] > > > > boot context, given that we cannot easily protect the command line from > > > > tampering without either adding complicated white/blacklisting of boot > > > > arguments or locking down the command line altogether. > > > > > > Not relying on the command line for finding the initrd image does not > > > secure the integrity and the validity of the initrd image. > > > > This patch isn't supposed to protect you against a bogus initrd and I don't > > think it should be the bootloaders job to verify that. The kernel already has > > tools to do that. > > How do you expect a bootloader identify if the initrd is compatible with > the kernel? Uh? Were exactly did i say that i expect that to happen? > > > > > > > > > A signature on the initrd image could solve the security problem you > > > describe. It would not require non-Linux software to be changed, and > > > would provide much better security. > > > > > > > The problem with parsing the kernel command line is that at the moment, > > different options are supported by different architectures. A quick grep for > > CONFIG_CMDLINE_(FORCE/OVERWRITE/EXTEND/FROM_BOOTLOADER) will give you an idea. > > > > What you can do in U-Boot currently is not have an environment in any of the > > flashes and set the bootdelay to 0, in order to prevent the user from > > changing that command line. > > If you don't have an environment or boot script how would > update-initramfs set the path of the initrd when it is updated? The path isn't hardcoded in any code here is it? This specifies a way for the linux stub to load the actual file. It's pretty a callback to the firmware. Were the firmware will find and how it will load it eventually is implementation specific. > > Using a UEFI variable seems to be the natural choice. > You might as well use that to specify were you should load the file from. The Loadfile2 (with the specified guid) implementation of the firmware will take care of that. > > > > > > > > > > In the second case, we force the bootloader to duplicate knowledge about > > > > the boot protocol which is already encoded in the stub, and which may be > > > > subject to change over time, e.g., bootparams struct definitions, memory > > > > allocation/alignment requirements for the placement of the initrd etc etc. > > > > In the ARM case, it also requires the bootloader to modify the hardware > > > > description provided by the firmware, as it is passed in the same file. > > > > On systems where the initrd is measured after loading, it creates a time > > > > window where the initrd contents might be manipulated in memory before > > > > handing over to the kernel. > > > > > > > > Address these concerns by adding support for loading the initrd into > > > > memory by invoking the EFI LoadFile2 protocol installed on a vendor > > > > GUIDed device path that specifically designates a Linux initrd. > > > > This addresses the above concerns, by putting the EFI stub in charge of > > > > placement in memory and of passing the base and size to the kernel proper > > > > (via whatever means it desires) while still leaving it up to the firmware > > > > or bootloader to obtain the file contents, potentially from other file > > > > systems than the one the kernel itself was loaded from. On platforms that > > > > implement measured boot, it permits the firmware to take the measurement > > > > right before the kernel actually consumes the contents. > > > > > > A firmware implementing the UEFI standard will not be aware of any > > > initrd image as such an object does not exist in the standard. It was a > > > wise decision that the UEFI standard is operating system agnostic > > > (accomodating BSD, Linux, Windows, etc.). So the firmware (EDK2, U-Boot, > > > etc.) seems to be out of scope for providing a Linux specific > > > EFI_LOAD_FILE2_PROTOCOL. > > > > > > When booting via GRUB it will be GRUB knowing which initrd to load. > > > > What about booting the kernel directly? > > > > > > > > Please, indicate which software you expect to expose the initrd related > > > EFI_LOAD_FILE2_PROTOCOL. > > > > I have an implementation for this on U-Boot which works. The file and device are > > hardcoded at the moment, but the rest of the functionality works fine. I'll > > share it with you once I clean it up a bit. > > Using a UEFI variable for passing the intird device path to Linux does > not require any change in U-Boot and is compatible with the UEFI > implementations of existing hardware like the laptop on which I am > writing this email. This still has the same issues we have now, uefi variable, kernel command line or whatever, it won't be common across architectures. Thanks /Ilias > > Best regards > > Heinrich > > > > > > > > > Using an UEFI variable for passing the initrd device path would be a > > > leaner solution on the bootloader side than requiring an extra > > > EFI_LOAD_FILE2_PROTOCOL implementation. > > > > > > > Thanks > > /Ilias > > > > > > > > > > Signed-off-by: Ard Biesheuvel > > > > --- > > > > drivers/firmware/efi/libstub/arm-stub.c | 16 +++-- > > > > drivers/firmware/efi/libstub/efi-stub-helper.c | 65 ++++++++++++++++++++ > > > > drivers/firmware/efi/libstub/efistub.h | 12 ++++ > > > > drivers/firmware/efi/libstub/x86-stub.c | 36 ++++++++++- > > > > include/linux/efi.h | 1 + > > > > 5 files changed, 123 insertions(+), 7 deletions(-) > > > > > > > > diff --git a/drivers/firmware/efi/libstub/arm-stub.c b/drivers/firmware/efi/libstub/arm-stub.c > > > > index c7b091f50e55..1db943c1ba2b 100644 > > > > --- a/drivers/firmware/efi/libstub/arm-stub.c > > > > +++ b/drivers/firmware/efi/libstub/arm-stub.c > > > > @@ -157,6 +157,7 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table_arg, > > > > enum efi_secureboot_mode secure_boot; > > > > struct screen_info *si; > > > > efi_properties_table_t *prop_tbl; > > > > + unsigned long max_addr; > > > > > > > > sys_table = sys_table_arg; > > > > > > > > @@ -255,11 +256,18 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table_arg, > > > > if (!fdt_addr) > > > > pr_efi("Generating empty DTB\n"); > > > > > > > > - status = efi_load_initrd(image, ULONG_MAX, > > > > - efi_get_max_initrd_addr(dram_base, *image_addr), > > > > - &initrd_addr, &initrd_size); > > > > + max_addr = efi_get_max_initrd_addr(dram_base, *image_addr); > > > > + status = efi_load_initrd_devpath(&initrd_addr, &initrd_size, max_addr); > > > > + if (status == EFI_SUCCESS) > > > > + pr_efi("Loaded initrd from LINUX_EFI_INITRD_MEDIA_GUID device path\n"); > > > > + else if (status == EFI_NOT_FOUND) { > > > > + status = efi_load_initrd(image, ULONG_MAX, max_addr, > > > > + &initrd_addr, &initrd_size); > > > > + if (status == EFI_SUCCESS) > > > > + pr_efi("Loaded initrd from command line option\n"); > > > > + } > > > > if (status != EFI_SUCCESS) > > > > - pr_efi_err("Failed initrd from command line!\n"); > > > > + pr_efi_err("Failed to load initrd!\n"); > > > > > > > > efi_random_get_seed(); > > > > > > > > diff --git a/drivers/firmware/efi/libstub/efi-stub-helper.c b/drivers/firmware/efi/libstub/efi-stub-helper.c > > > > index 8e60a39df3c5..eaf45ea749b3 100644 > > > > --- a/drivers/firmware/efi/libstub/efi-stub-helper.c > > > > +++ b/drivers/firmware/efi/libstub/efi-stub-helper.c > > > > @@ -323,3 +323,68 @@ void efi_char16_printk(efi_char16_t *str) > > > > efi_call_proto(efi_table_attr(efi_system_table(), con_out), > > > > output_string, str); > > > > } > > > > + > > > > +static const struct { > > > > + struct efi_vendor_dev_path vendor; > > > > + struct efi_generic_dev_path end; > > > > +} __packed initrd_devpath = { > > > > + { > > > > + EFI_DEV_MEDIA, > > > > + EFI_DEV_MEDIA_VENDOR, > > > > + sizeof(struct efi_vendor_dev_path), > > > > + LINUX_EFI_INITRD_MEDIA_GUID > > > > + }, { > > > > + EFI_DEV_END_PATH, > > > > + EFI_DEV_END_ENTIRE, > > > > + sizeof(struct efi_generic_dev_path) > > > > + } > > > > +}; > > > > + > > > > +efi_status_t efi_load_initrd_devpath(unsigned long *load_addr, > > > > + unsigned long *load_size, > > > > + unsigned long max) > > > > +{ > > > > + efi_guid_t lf2_proto_guid = EFI_LOAD_FILE2_PROTOCOL_GUID; > > > > + efi_device_path_protocol_t *dp; > > > > + efi_load_file2_protocol_t *lf2; > > > > + unsigned long initrd_addr; > > > > + unsigned long initrd_size; > > > > + efi_handle_t handle; > > > > + efi_status_t status; > > > > + > > > > + if (!load_addr || !load_size) > > > > + return EFI_INVALID_PARAMETER; > > > > + > > > > + dp = (efi_device_path_protocol_t *)&initrd_devpath; > > > > + status = efi_bs_call(locate_device_path, &lf2_proto_guid, &dp, &handle); > > > > + if (status != EFI_SUCCESS) > > > > + return status; > > > > + > > > > + status = efi_bs_call(handle_protocol, handle, &lf2_proto_guid, > > > > + (void **)&lf2); > > > > + if (status != EFI_SUCCESS) > > > > + return status; > > > > > > You require here that there is a handle exposing the device path > > > protocol with the initrd specific device path. On the same handle the > > > EFI_LOAD_FILE2_PROTOCOL must be installed which will load the initrd > > > file when called with the same device path. > > > > > > An alternative implementation would simple loop over all instances of > > > the EFI_LOAD_FILE2_PROTOCOL and try to load the initrd. > > > > > > It would be worthwhile to describe the requirements on the > > > implementation of the EFI_LOAD_FILE2_PROTOCOL in a code comment and in > > > the documentation. > > > > > > Unfortunately the documentation of UEFI has been duplicated into two files: > > > > > > Documentation/arm/uefi.rst > > > Documentation/x86/x86_64/uefi.rst > > > > > > Best regards > > > > > > Heinrich > > > > > > > + > > > > + initrd_size = 0; > > > > + status = efi_call_proto(lf2, load_file, > > > > + (efi_device_path_protocol_t *)&initrd_devpath, > > > > + false, &initrd_size, NULL); > > > > + if (status != EFI_BUFFER_TOO_SMALL) > > > > + return EFI_LOAD_ERROR; > > > > + > > > > + status = efi_allocate_pages(initrd_size, &initrd_addr, max); > > > > + if (status != EFI_SUCCESS) > > > > + return status; > > > > + > > > > + status = efi_call_proto(lf2, load_file, > > > > + (efi_device_path_protocol_t *)&initrd_devpath, > > > > + false, &initrd_size, (void *)initrd_addr); > > > > + if (status != EFI_SUCCESS) { > > > > + efi_free(initrd_size, initrd_addr); > > > > + return status; > > > > + } > > > > + > > > > + *load_addr = initrd_addr; > > > > + *load_size = initrd_size; > > > > + return EFI_SUCCESS; > > > > +} > > > > diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h > > > > index 99e93fd76ec5..fbf9f9442eed 100644 > > > > --- a/drivers/firmware/efi/libstub/efistub.h > > > > +++ b/drivers/firmware/efi/libstub/efistub.h > > > > @@ -566,6 +566,14 @@ union efi_load_file_protocol { > > > > } mixed_mode; > > > > }; > > > > > > > > +struct efi_vendor_dev_path { > > > > + u8 type; > > > > + u8 sub_type; > > > > + u16 length; > > > > + efi_guid_t vendorguid; > > > > + u8 vendordata[]; > > > > +} __packed; > > > > + > > > > void efi_pci_disable_bridge_busmaster(void); > > > > > > > > typedef efi_status_t (*efi_exit_boot_map_processing)( > > > > @@ -651,4 +659,8 @@ efi_status_t efi_load_initrd(efi_loaded_image_t *image, > > > > unsigned long *load_addr, > > > > unsigned long *load_size); > > > > > > > > +efi_status_t efi_load_initrd_devpath(unsigned long *load_addr, > > > > + unsigned long *load_size, > > > > + unsigned long max); > > > > + > > > > #endif > > > > diff --git a/drivers/firmware/efi/libstub/x86-stub.c b/drivers/firmware/efi/libstub/x86-stub.c > > > > index f3e2ff31b624..7f38f95676dd 100644 > > > > --- a/drivers/firmware/efi/libstub/x86-stub.c > > > > +++ b/drivers/firmware/efi/libstub/x86-stub.c > > > > @@ -419,9 +419,20 @@ efi_status_t __efiapi efi_pe_entry(efi_handle_t handle, > > > > if (status != EFI_SUCCESS) > > > > goto fail2; > > > > > > > > - status = efi_load_initrd(image, hdr->initrd_addr_max, > > > > - above4g ? ULONG_MAX : hdr->initrd_addr_max, > > > > - &ramdisk_addr, &ramdisk_size); > > > > + /* > > > > + * The initrd loaded from the Linux initrd vendor device > > > > + * path should take precedence, as we don't want the > > > > + * [unverified] command line to override the initrd > > > > + * supplied by the [potentially verified] firmware. > > > > + */ > > > > + status = efi_load_initrd_devpath(&ramdisk_addr, &ramdisk_size, > > > > + above4g ? ULONG_MAX > > > > + : hdr->initrd_addr_max); > > > > + if (status == EFI_NOT_FOUND) > > > > + status = efi_load_initrd(image, hdr->initrd_addr_max, > > > > + above4g ? ULONG_MAX > > > > + : hdr->initrd_addr_max, > > > > + &ramdisk_addr, &ramdisk_size); > > > > if (status != EFI_SUCCESS) > > > > goto fail2; > > > > hdr->ramdisk_image = ramdisk_addr & 0xffffffff; > > > > @@ -732,6 +743,25 @@ struct boot_params *efi_main(efi_handle_t handle, > > > > ((u64)boot_params->ext_cmd_line_ptr << 32)); > > > > efi_parse_options((char *)cmdline_paddr); > > > > > > > > + if (!hdr->ramdisk_size && !boot_params->ext_ramdisk_size) { > > > > + unsigned long max = hdr->initrd_addr_max; > > > > + unsigned long addr, size; > > > > + > > > > + if (hdr->xloadflags & XLF_CAN_BE_LOADED_ABOVE_4G) > > > > + max = ULONG_MAX; > > > > + > > > > + status = efi_load_initrd_devpath(&addr, &size, max); > > > > + if (status == EFI_SUCCESS) { > > > > + hdr->ramdisk_image = (u32)addr; > > > > + hdr->ramdisk_size = (u32)size; > > > > + boot_params->ext_ramdisk_image = (u64)addr >> 32; > > > > + boot_params->ext_ramdisk_size = (u64)size >> 32; > > > > + } else if (status != EFI_NOT_FOUND) { > > > > + efi_printk("efi_load_initrd_devpath() failed!\n"); > > > > + goto fail; > > > > + } > > > > + } > > > > + > > > > /* > > > > * If the boot loader gave us a value for secure_boot then we use that, > > > > * otherwise we ask the BIOS. > > > > diff --git a/include/linux/efi.h b/include/linux/efi.h > > > > index 9ccf313fe9de..75c83c322c40 100644 > > > > --- a/include/linux/efi.h > > > > +++ b/include/linux/efi.h > > > > @@ -353,6 +353,7 @@ void efi_native_runtime_setup(void); > > > > #define LINUX_EFI_TPM_EVENT_LOG_GUID EFI_GUID(0xb7799cb0, 0xeca2, 0x4943, 0x96, 0x67, 0x1f, 0xae, 0x07, 0xb7, 0x47, 0xfa) > > > > #define LINUX_EFI_TPM_FINAL_LOG_GUID EFI_GUID(0x1e2ed096, 0x30e2, 0x4254, 0xbd, 0x89, 0x86, 0x3b, 0xbe, 0xf8, 0x23, 0x25) > > > > #define LINUX_EFI_MEMRESERVE_TABLE_GUID EFI_GUID(0x888eb0c6, 0x8ede, 0x4ff5, 0xa8, 0xf0, 0x9a, 0xee, 0x5c, 0xb9, 0x77, 0xc2) > > > > +#define LINUX_EFI_INITRD_MEDIA_GUID EFI_GUID(0x5568e427, 0x68fc, 0x4f3d, 0xac, 0x74, 0xca, 0x55, 0x52, 0x31, 0xcc, 0x68) > > > > > > > > /* OEM GUIDs */ > > > > #define DELLEMC_EFI_RCI2_TABLE_GUID EFI_GUID(0x2d9f28a2, 0xa886, 0x456a, 0x97, 0xa8, 0xf1, 0x1e, 0xf2, 0x4f, 0xf4, 0x55) > > > > > > > > From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BAD31C35247 for ; 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[94.66.201.28]) by smtp.gmail.com with ESMTPSA id n13sm659793wmd.21.2020.02.06.12.09.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 06 Feb 2020 12:09:42 -0800 (PST) Date: Thu, 6 Feb 2020 22:09:40 +0200 From: Ilias Apalodimas To: Heinrich Schuchardt Subject: Re: [PATCH 1/2] efi/libstub: add support for loading the initrd from a device path Message-ID: <20200206200940.GA750064@apalos.home> References: <20200206140352.6300-1-ardb@kernel.org> <20200206140352.6300-2-ardb@kernel.org> <20200206184608.GA749195@apalos.home> <2ffcb05e-761a-9345-7da5-c08f5cda914e@gmx.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <2ffcb05e-761a-9345-7da5-c08f5cda914e@gmx.de> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200206_120949_647020_364D70B8 X-CRM114-Status: GOOD ( 47.15 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-efi@vger.kernel.org, agraf@csgraf.de, daniel.kiper@oracle.com, mjg59@google.com, pjones@redhat.com, leif@nuviainc.com, lersek@redhat.com, Ard Biesheuvel , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Feb 06, 2020 at 08:15:11PM +0100, Heinrich Schuchardt wrote: > On 2/6/20 7:46 PM, Ilias Apalodimas wrote: > > Hi Heinrich, > > > > I actually like the approach. > > > > On Thu, Feb 06, 2020 at 07:26:20PM +0100, Heinrich Schuchardt wrote: > > [...] > > > > boot context, given that we cannot easily protect the command line from > > > > tampering without either adding complicated white/blacklisting of boot > > > > arguments or locking down the command line altogether. > > > > > > Not relying on the command line for finding the initrd image does not > > > secure the integrity and the validity of the initrd image. > > > > This patch isn't supposed to protect you against a bogus initrd and I don't > > think it should be the bootloaders job to verify that. The kernel already has > > tools to do that. > > How do you expect a bootloader identify if the initrd is compatible with > the kernel? Uh? Were exactly did i say that i expect that to happen? > > > > > > > > > A signature on the initrd image could solve the security problem you > > > describe. It would not require non-Linux software to be changed, and > > > would provide much better security. > > > > > > > The problem with parsing the kernel command line is that at the moment, > > different options are supported by different architectures. A quick grep for > > CONFIG_CMDLINE_(FORCE/OVERWRITE/EXTEND/FROM_BOOTLOADER) will give you an idea. > > > > What you can do in U-Boot currently is not have an environment in any of the > > flashes and set the bootdelay to 0, in order to prevent the user from > > changing that command line. > > If you don't have an environment or boot script how would > update-initramfs set the path of the initrd when it is updated? The path isn't hardcoded in any code here is it? This specifies a way for the linux stub to load the actual file. It's pretty a callback to the firmware. Were the firmware will find and how it will load it eventually is implementation specific. > > Using a UEFI variable seems to be the natural choice. > You might as well use that to specify were you should load the file from. The Loadfile2 (with the specified guid) implementation of the firmware will take care of that. > > > > > > > > > > In the second case, we force the bootloader to duplicate knowledge about > > > > the boot protocol which is already encoded in the stub, and which may be > > > > subject to change over time, e.g., bootparams struct definitions, memory > > > > allocation/alignment requirements for the placement of the initrd etc etc. > > > > In the ARM case, it also requires the bootloader to modify the hardware > > > > description provided by the firmware, as it is passed in the same file. > > > > On systems where the initrd is measured after loading, it creates a time > > > > window where the initrd contents might be manipulated in memory before > > > > handing over to the kernel. > > > > > > > > Address these concerns by adding support for loading the initrd into > > > > memory by invoking the EFI LoadFile2 protocol installed on a vendor > > > > GUIDed device path that specifically designates a Linux initrd. > > > > This addresses the above concerns, by putting the EFI stub in charge of > > > > placement in memory and of passing the base and size to the kernel proper > > > > (via whatever means it desires) while still leaving it up to the firmware > > > > or bootloader to obtain the file contents, potentially from other file > > > > systems than the one the kernel itself was loaded from. On platforms that > > > > implement measured boot, it permits the firmware to take the measurement > > > > right before the kernel actually consumes the contents. > > > > > > A firmware implementing the UEFI standard will not be aware of any > > > initrd image as such an object does not exist in the standard. It was a > > > wise decision that the UEFI standard is operating system agnostic > > > (accomodating BSD, Linux, Windows, etc.). So the firmware (EDK2, U-Boot, > > > etc.) seems to be out of scope for providing a Linux specific > > > EFI_LOAD_FILE2_PROTOCOL. > > > > > > When booting via GRUB it will be GRUB knowing which initrd to load. > > > > What about booting the kernel directly? > > > > > > > > Please, indicate which software you expect to expose the initrd related > > > EFI_LOAD_FILE2_PROTOCOL. > > > > I have an implementation for this on U-Boot which works. The file and device are > > hardcoded at the moment, but the rest of the functionality works fine. I'll > > share it with you once I clean it up a bit. > > Using a UEFI variable for passing the intird device path to Linux does > not require any change in U-Boot and is compatible with the UEFI > implementations of existing hardware like the laptop on which I am > writing this email. This still has the same issues we have now, uefi variable, kernel command line or whatever, it won't be common across architectures. Thanks /Ilias > > Best regards > > Heinrich > > > > > > > > > Using an UEFI variable for passing the initrd device path would be a > > > leaner solution on the bootloader side than requiring an extra > > > EFI_LOAD_FILE2_PROTOCOL implementation. > > > > > > > Thanks > > /Ilias > > > > > > > > > > Signed-off-by: Ard Biesheuvel > > > > --- > > > > drivers/firmware/efi/libstub/arm-stub.c | 16 +++-- > > > > drivers/firmware/efi/libstub/efi-stub-helper.c | 65 ++++++++++++++++++++ > > > > drivers/firmware/efi/libstub/efistub.h | 12 ++++ > > > > drivers/firmware/efi/libstub/x86-stub.c | 36 ++++++++++- > > > > include/linux/efi.h | 1 + > > > > 5 files changed, 123 insertions(+), 7 deletions(-) > > > > > > > > diff --git a/drivers/firmware/efi/libstub/arm-stub.c b/drivers/firmware/efi/libstub/arm-stub.c > > > > index c7b091f50e55..1db943c1ba2b 100644 > > > > --- a/drivers/firmware/efi/libstub/arm-stub.c > > > > +++ b/drivers/firmware/efi/libstub/arm-stub.c > > > > @@ -157,6 +157,7 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table_arg, > > > > enum efi_secureboot_mode secure_boot; > > > > struct screen_info *si; > > > > efi_properties_table_t *prop_tbl; > > > > + unsigned long max_addr; > > > > > > > > sys_table = sys_table_arg; > > > > > > > > @@ -255,11 +256,18 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table_arg, > > > > if (!fdt_addr) > > > > pr_efi("Generating empty DTB\n"); > > > > > > > > - status = efi_load_initrd(image, ULONG_MAX, > > > > - efi_get_max_initrd_addr(dram_base, *image_addr), > > > > - &initrd_addr, &initrd_size); > > > > + max_addr = efi_get_max_initrd_addr(dram_base, *image_addr); > > > > + status = efi_load_initrd_devpath(&initrd_addr, &initrd_size, max_addr); > > > > + if (status == EFI_SUCCESS) > > > > + pr_efi("Loaded initrd from LINUX_EFI_INITRD_MEDIA_GUID device path\n"); > > > > + else if (status == EFI_NOT_FOUND) { > > > > + status = efi_load_initrd(image, ULONG_MAX, max_addr, > > > > + &initrd_addr, &initrd_size); > > > > + if (status == EFI_SUCCESS) > > > > + pr_efi("Loaded initrd from command line option\n"); > > > > + } > > > > if (status != EFI_SUCCESS) > > > > - pr_efi_err("Failed initrd from command line!\n"); > > > > + pr_efi_err("Failed to load initrd!\n"); > > > > > > > > efi_random_get_seed(); > > > > > > > > diff --git a/drivers/firmware/efi/libstub/efi-stub-helper.c b/drivers/firmware/efi/libstub/efi-stub-helper.c > > > > index 8e60a39df3c5..eaf45ea749b3 100644 > > > > --- a/drivers/firmware/efi/libstub/efi-stub-helper.c > > > > +++ b/drivers/firmware/efi/libstub/efi-stub-helper.c > > > > @@ -323,3 +323,68 @@ void efi_char16_printk(efi_char16_t *str) > > > > efi_call_proto(efi_table_attr(efi_system_table(), con_out), > > > > output_string, str); > > > > } > > > > + > > > > +static const struct { > > > > + struct efi_vendor_dev_path vendor; > > > > + struct efi_generic_dev_path end; > > > > +} __packed initrd_devpath = { > > > > + { > > > > + EFI_DEV_MEDIA, > > > > + EFI_DEV_MEDIA_VENDOR, > > > > + sizeof(struct efi_vendor_dev_path), > > > > + LINUX_EFI_INITRD_MEDIA_GUID > > > > + }, { > > > > + EFI_DEV_END_PATH, > > > > + EFI_DEV_END_ENTIRE, > > > > + sizeof(struct efi_generic_dev_path) > > > > + } > > > > +}; > > > > + > > > > +efi_status_t efi_load_initrd_devpath(unsigned long *load_addr, > > > > + unsigned long *load_size, > > > > + unsigned long max) > > > > +{ > > > > + efi_guid_t lf2_proto_guid = EFI_LOAD_FILE2_PROTOCOL_GUID; > > > > + efi_device_path_protocol_t *dp; > > > > + efi_load_file2_protocol_t *lf2; > > > > + unsigned long initrd_addr; > > > > + unsigned long initrd_size; > > > > + efi_handle_t handle; > > > > + efi_status_t status; > > > > + > > > > + if (!load_addr || !load_size) > > > > + return EFI_INVALID_PARAMETER; > > > > + > > > > + dp = (efi_device_path_protocol_t *)&initrd_devpath; > > > > + status = efi_bs_call(locate_device_path, &lf2_proto_guid, &dp, &handle); > > > > + if (status != EFI_SUCCESS) > > > > + return status; > > > > + > > > > + status = efi_bs_call(handle_protocol, handle, &lf2_proto_guid, > > > > + (void **)&lf2); > > > > + if (status != EFI_SUCCESS) > > > > + return status; > > > > > > You require here that there is a handle exposing the device path > > > protocol with the initrd specific device path. On the same handle the > > > EFI_LOAD_FILE2_PROTOCOL must be installed which will load the initrd > > > file when called with the same device path. > > > > > > An alternative implementation would simple loop over all instances of > > > the EFI_LOAD_FILE2_PROTOCOL and try to load the initrd. > > > > > > It would be worthwhile to describe the requirements on the > > > implementation of the EFI_LOAD_FILE2_PROTOCOL in a code comment and in > > > the documentation. > > > > > > Unfortunately the documentation of UEFI has been duplicated into two files: > > > > > > Documentation/arm/uefi.rst > > > Documentation/x86/x86_64/uefi.rst > > > > > > Best regards > > > > > > Heinrich > > > > > > > + > > > > + initrd_size = 0; > > > > + status = efi_call_proto(lf2, load_file, > > > > + (efi_device_path_protocol_t *)&initrd_devpath, > > > > + false, &initrd_size, NULL); > > > > + if (status != EFI_BUFFER_TOO_SMALL) > > > > + return EFI_LOAD_ERROR; > > > > + > > > > + status = efi_allocate_pages(initrd_size, &initrd_addr, max); > > > > + if (status != EFI_SUCCESS) > > > > + return status; > > > > + > > > > + status = efi_call_proto(lf2, load_file, > > > > + (efi_device_path_protocol_t *)&initrd_devpath, > > > > + false, &initrd_size, (void *)initrd_addr); > > > > + if (status != EFI_SUCCESS) { > > > > + efi_free(initrd_size, initrd_addr); > > > > + return status; > > > > + } > > > > + > > > > + *load_addr = initrd_addr; > > > > + *load_size = initrd_size; > > > > + return EFI_SUCCESS; > > > > +} > > > > diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h > > > > index 99e93fd76ec5..fbf9f9442eed 100644 > > > > --- a/drivers/firmware/efi/libstub/efistub.h > > > > +++ b/drivers/firmware/efi/libstub/efistub.h > > > > @@ -566,6 +566,14 @@ union efi_load_file_protocol { > > > > } mixed_mode; > > > > }; > > > > > > > > +struct efi_vendor_dev_path { > > > > + u8 type; > > > > + u8 sub_type; > > > > + u16 length; > > > > + efi_guid_t vendorguid; > > > > + u8 vendordata[]; > > > > +} __packed; > > > > + > > > > void efi_pci_disable_bridge_busmaster(void); > > > > > > > > typedef efi_status_t (*efi_exit_boot_map_processing)( > > > > @@ -651,4 +659,8 @@ efi_status_t efi_load_initrd(efi_loaded_image_t *image, > > > > unsigned long *load_addr, > > > > unsigned long *load_size); > > > > > > > > +efi_status_t efi_load_initrd_devpath(unsigned long *load_addr, > > > > + unsigned long *load_size, > > > > + unsigned long max); > > > > + > > > > #endif > > > > diff --git a/drivers/firmware/efi/libstub/x86-stub.c b/drivers/firmware/efi/libstub/x86-stub.c > > > > index f3e2ff31b624..7f38f95676dd 100644 > > > > --- a/drivers/firmware/efi/libstub/x86-stub.c > > > > +++ b/drivers/firmware/efi/libstub/x86-stub.c > > > > @@ -419,9 +419,20 @@ efi_status_t __efiapi efi_pe_entry(efi_handle_t handle, > > > > if (status != EFI_SUCCESS) > > > > goto fail2; > > > > > > > > - status = efi_load_initrd(image, hdr->initrd_addr_max, > > > > - above4g ? ULONG_MAX : hdr->initrd_addr_max, > > > > - &ramdisk_addr, &ramdisk_size); > > > > + /* > > > > + * The initrd loaded from the Linux initrd vendor device > > > > + * path should take precedence, as we don't want the > > > > + * [unverified] command line to override the initrd > > > > + * supplied by the [potentially verified] firmware. > > > > + */ > > > > + status = efi_load_initrd_devpath(&ramdisk_addr, &ramdisk_size, > > > > + above4g ? ULONG_MAX > > > > + : hdr->initrd_addr_max); > > > > + if (status == EFI_NOT_FOUND) > > > > + status = efi_load_initrd(image, hdr->initrd_addr_max, > > > > + above4g ? ULONG_MAX > > > > + : hdr->initrd_addr_max, > > > > + &ramdisk_addr, &ramdisk_size); > > > > if (status != EFI_SUCCESS) > > > > goto fail2; > > > > hdr->ramdisk_image = ramdisk_addr & 0xffffffff; > > > > @@ -732,6 +743,25 @@ struct boot_params *efi_main(efi_handle_t handle, > > > > ((u64)boot_params->ext_cmd_line_ptr << 32)); > > > > efi_parse_options((char *)cmdline_paddr); > > > > > > > > + if (!hdr->ramdisk_size && !boot_params->ext_ramdisk_size) { > > > > + unsigned long max = hdr->initrd_addr_max; > > > > + unsigned long addr, size; > > > > + > > > > + if (hdr->xloadflags & XLF_CAN_BE_LOADED_ABOVE_4G) > > > > + max = ULONG_MAX; > > > > + > > > > + status = efi_load_initrd_devpath(&addr, &size, max); > > > > + if (status == EFI_SUCCESS) { > > > > + hdr->ramdisk_image = (u32)addr; > > > > + hdr->ramdisk_size = (u32)size; > > > > + boot_params->ext_ramdisk_image = (u64)addr >> 32; > > > > + boot_params->ext_ramdisk_size = (u64)size >> 32; > > > > + } else if (status != EFI_NOT_FOUND) { > > > > + efi_printk("efi_load_initrd_devpath() failed!\n"); > > > > + goto fail; > > > > + } > > > > + } > > > > + > > > > /* > > > > * If the boot loader gave us a value for secure_boot then we use that, > > > > * otherwise we ask the BIOS. > > > > diff --git a/include/linux/efi.h b/include/linux/efi.h > > > > index 9ccf313fe9de..75c83c322c40 100644 > > > > --- a/include/linux/efi.h > > > > +++ b/include/linux/efi.h > > > > @@ -353,6 +353,7 @@ void efi_native_runtime_setup(void); > > > > #define LINUX_EFI_TPM_EVENT_LOG_GUID EFI_GUID(0xb7799cb0, 0xeca2, 0x4943, 0x96, 0x67, 0x1f, 0xae, 0x07, 0xb7, 0x47, 0xfa) > > > > #define LINUX_EFI_TPM_FINAL_LOG_GUID EFI_GUID(0x1e2ed096, 0x30e2, 0x4254, 0xbd, 0x89, 0x86, 0x3b, 0xbe, 0xf8, 0x23, 0x25) > > > > #define LINUX_EFI_MEMRESERVE_TABLE_GUID EFI_GUID(0x888eb0c6, 0x8ede, 0x4ff5, 0xa8, 0xf0, 0x9a, 0xee, 0x5c, 0xb9, 0x77, 0xc2) > > > > +#define LINUX_EFI_INITRD_MEDIA_GUID EFI_GUID(0x5568e427, 0x68fc, 0x4f3d, 0xac, 0x74, 0xca, 0x55, 0x52, 0x31, 0xcc, 0x68) > > > > > > > > /* OEM GUIDs */ > > > > #define DELLEMC_EFI_RCI2_TABLE_GUID EFI_GUID(0x2d9f28a2, 0xa886, 0x456a, 0x97, 0xa8, 0xf1, 0x1e, 0xf2, 0x4f, 0xf4, 0x55) > > > > > > > > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel