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* [image] Generalise concept of selected imageMichael Brown2023-05-171-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Most image flags are independent values: any combination of flags may be set for any image, and the flags for one image are independent of the flags for any other image. The "selected" flag does not follow this pattern: at most one image may be marked as selected at any time. When invoking a kernel via the UEFI shim, there will be multiple "special" images: the selected kernel itself, the shim image, and potentially a shim-signed GRUB binary to be used as a crutch to assist shim in loading the kernel (since current versions of the UEFI shim are not capable of directly loading a Linux kernel). Remove the "selected" image flag and replace it with a general concept of an image tag with the same semantics: a given tag may be assigned to at most one image, an image may be found by its tag only while the image is currently registered, and a tag will survive unregistration and reregistration of an image (if it has not already been assigned to a new image). For visual consistency, also replace the current image pointer with a current image tag. The image pointer stored within the image tag holds only a weak reference to the image, since the selection of an image should not prevent that image from being freed. (The strong reference to the currently executing image is held locally within the execution scope of image_exec(), and is logically separate from the current image pointer.) Signed-off-by: Michael Brown <mcb30@ipxe.org>
* [efi] Allow currently selected image to be opened as "grub*.efi"Michael Brown2023-05-051-0/+11
| | | | | | | | | | | | | | | | | | | | | Versions 15.4 and earlier of the UEFI shim are incapable of correctly parsing the command line in order to extract the second stage loader filename, and will always attempt to load "grubx64.efi" or equivalent. Versions 15.3 and later of the UEFI shim are currently incapable of loading a Linux kernel directly anyway, since the kernel does not include SBAT metadata. These versions will require a genuine shim-signed GRUB binary to be used as a crutch to assist shim in loading a Linux kernel. This leaves versions 15.2 and earlier of the UEFI shim (as currently used in e.g. RHEL7) as being capable of directly loading a Linux kernel, but incorrectly attempting to load it using the filename "grubx64.efi" or equivalent. To support the bugs in these older versions of the UEFI shim, allow the currently selected image to be opened via any filename of the form "grub*.efi". Signed-off-by: Michael Brown <mcb30@ipxe.org>
* [image] Allow for images to be hidden from lists of all imagesMichael Brown2023-05-051-10/+26
| | | | | | | | | | | | | | | When invoking a kernel via the UEFI shim, the kernel (and potentially also a helper binary such as GRUB) must be accessible via the virtual filesystem exposed via EFI_SIMPLE_FILE_SYSTEM_PROTOCOL but must not be present in the magic initrd constructed from all registered images. Allow for images to be flagged as hidden, which will cause them to be excluded from API-level lists of all images such as the virtual filesystem directory contents, the magic initrd, or the Multiboot module list. Hidden images remain visible to iPXE commands including "imgstat", which will show a "[HIDDEN]" flag for such images. Signed-off-by: Michael Brown <mcb30@ipxe.org>
* [efi] Show original filenames in debug messagesMichael Brown2023-05-051-8/+16
| | | | | | | Show the original filename as used by the consumer when calling our EFI_SIMPLE_FILE_SYSTEM_PROTOCOL's Open() method. Signed-off-by: Michael Brown <mcb30@ipxe.org>
* [efi] Allow downloaded images to take precedence over constructed filesMichael Brown2023-05-051-22/+33
| | | | | | | | | Try searching for a matching registered image before checking for fixed filenames (such as "initrd.magic" for the dynamically generated magic initrd file). This minimises surprise by ensuring that an explicitly downloaded image will always be used verbatim. Signed-off-by: Michael Brown <mcb30@ipxe.org>
* [efi] Claim fixed device paths by uninstalling device path protocolMichael Brown2023-03-151-122/+172
| | | | | | | | | | | | | | | | | | | | | | | | | | As documented in commits 6a004be ("[efi] Support the initrd autodetection mechanism in newer Linux kernels") and 04e60a2 ("[efi] Omit EFI_LOAD_FILE2_PROTOCOL for a zero-length initrd"), the choice in Linux of using a fixed device path requires bootloaders to allow for the fact that a previous bootloader may have already installed a handle with the fixed device path. We currently deal with this situation by reusing the existing handle, replacing the EFI_LOAD_FILE2_PROTOCOL instance with our own. Simplify the code by instead uninstalling the EFI_DEVICE_PATH_PROTOCOL instance from the existing handle (if present), thereby allowing the creation of a new handle to succeed. Create the new handle only if we have a non-empty initrd to provide. This works around bugs in bootloaders such as the systemd EFI stub that fail to allow for the existence of multiple-bootloader chains. (The workaround is not comprehensive: if the user has downloaded other images in iPXE before invoking the systemd Unified Kernel Image (UKI), then the systemd EFI stub will still crash and burn since it fails to allow for the fact that a previous bootloader has already installed a handle with the fixed device path.) Signed-off-by: Michael Brown <mcb30@ipxe.org>
* [image] Always unregister currently executing imageMichael Brown2023-03-071-5/+1Star
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | We unregister script images during their execution, to prevent a "boot" command from re-executing the containing script. This also has the side effect of preventing executing scripts from showing up within the Linux magic initrd image (or the Multiboot module list). Additional logic in bzimage.c and efi_file.c prevents a currently executing kernel from showing up within the magic initrd image. Similar logic in multiboot.c prevents the Multiboot kernel from showing up as a Multiboot module. This still leaves some corner cases that are not covered correctly. For example: when using a gzip-compressed kernel image, nothing will currently hide the original compressed image from the magic initrd. Fix by moving the logic that temporarily unregisters the current image from script_exec() to image_exec(), so that it applies to all image types, and simplify the magic initrd and Multiboot module list construction logic on the basis that no further filtering of the registered image list is necessary. This change has the side effect of hiding currently executing EFI images from the virtual filesystem exposed by iPXE. For example, when using iPXE to boot wimboot, the wimboot binary itself will no longer be visible within the virtual filesystem. Signed-off-by: Michael Brown <mcb30@ipxe.org>
* [image] Consistently use for_each_image() to iterate over imagesMichael Brown2023-03-061-1/+1
| | | | Signed-off-by: Michael Brown <mcb30@ipxe.org>
* [efi] Omit EFI_LOAD_FILE2_PROTOCOL for a zero-length initrdMichael Brown2023-02-281-2/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When the Linux kernel is being used with no initrd, iPXE will still provide a zero-length initrd.magic file within the virtual filesystem. As of commit 6a004be ("[efi] Support the initrd autodetection mechanism in newer Linux kernels"), this zero-length file will also be exposed via an EFI_LOAD_FILE2_PROTOCOL instance on a handle with a fixed device path. The correct handling of zero-length files via EFI_LOAD_FILE2_PROTOCOL is unfortunately not well defined. Linux expects the first call to LoadFile() to always fail with EFI_BUFFER_TOO_SMALL. When the initrd is genuinely zero-length, iPXE will return success since the buffer is not too small to hold the (zero-length) file. This causes Linux to immediately report a spurious EFI_LOAD_ERROR boot failure. We could change the logic in iPXE's efi_file_load() to always return EFI_BUFFER_TOO_SMALL if Buffer is NULL on entry. Since the correct behaviour of LoadFile() in the corner case of a zero-length file is left undefined by the UEFI specification, this would be permissible. Unfortunately this approach would not fix the problem. If we return EFI_BUFFER_TOO_SMALL and set the file length to zero, then Linux will call the boot services AllocatePages() method with a zero length. In at least the EDK2 implementation, this combination of parameters will cause AllocatePages() to return EFI_OUT_OF_RESOURCES, and Linux will again report a boot failure. Another approach would be to install the initrd device path handle only if we have a non-empty initrd to offer. Unfortunately this would lead to a failure in yet another corner case: if a previous bootloader has installed an initrd device path handle (e.g. to pass a boot script to iPXE) then we must not leave that initrd in place, since then our loaded kernel would end up seeing the wrong initrd content. The cleanest fix seems to be to ensure that the initrd device path handle is installed with the EFI_DEVICE_PATH_PROTOCOL instance present but with the EFI_LOAD_FILE2_PROTOCOL instance absent (and forcibly uninstalled if necessary), matching the state in which we leave the handle after uninstalling our virtual filesystem. Linux will then not find any handle that supports EFI_LOAD_FILE2_PROTOCOL within the fixed device path, and so will fall through to trying other mechanisms to locate the initrd. Reported-by: Chris Bradshaw <cwbshaw@gmail.com> Signed-off-by: Michael Brown <mcb30@ipxe.org>
* [efi] Support the initrd autodetection mechanism in newer Linux kernelsMichael Brown2023-02-151-0/+190
| | | | | | | | | | | | | | | | | | | | | | | | | | | Linux 5.7 added the ability to autodetect an initrd by searching for a handle via a fixed vendor-specific "Linux initrd device path" and then locating and using the EFI_LOAD_FILE2_PROTOCOL instance on that handle. This maps quite naturally onto our existing concept of a "magic initrd" as introduced for EFI in commit e5f0255 ("[efi] Provide an "initrd.magic" file for use by UEFI kernels"). Add an EFI_LOAD_FILE2_PROTOCOL instance to our EFI virtual files (backed by simply calling the existing EFI_SIMPLE_FILE_SYSTEM_PROTOCOL method to read from the file), and install the protocol instance for the "initrd.magic" virtual file onto a new device handle that also provides the Linux initrd device path. The design choice in Linux of using a single fixed device path makes this unfortunately messy to support, since device paths must be unique within a system. When multiple bootloaders are used (e.g. GRUB loading iPXE loading Linux) then only one bootloader can ever install the device path onto a handle. Subsequent bootloaders must locate the existing handle and replace the load file protocol instance with their own. Signed-off-by: Michael Brown <mcb30@ipxe.org>
* [efi] Fix debug message when reading from EFI virtual filesMichael Brown2023-02-151-1/+1
| | | | | | | Show the requested range when a caller reads from a virtual file via the EFI_SIMPLE_FILE_SYSTEM_PROTOCOL interface. Signed-off-by: Michael Brown <mcb30@ipxe.org>
* [efi] Provide an "initrd.magic" file for use by UEFI kernelsMichael Brown2021-05-211-0/+88
| | | | | | | | | | | | | | | | | | | | | | | Provide a file "initrd.magic" via the EFI_SIMPLE_FILE_SYSTEM_PROTOCOL that contains the initrd file as constructed for BIOS bzImage kernels (including injected files with CPIO headers constructed by iPXE). This allows BIOS and UEFI kernels to obtain the exact same initramfs image, by adding "initrd=initrd.magic" to the kernel command line. For example: #!ipxe kernel boot/vmlinuz initrd=initrd.magic initrd boot/initrd.img initrd boot/modules/e1000.ko /lib/modules/e1000.ko initrd boot/modules/af_packet.ko /lib/modules/af_packet.ko boot Do not include the "initrd.magic" file within the root directory listing, since doing so would break software such as wimboot that processes all files within the root directory. Signed-off-by: Michael Brown <mcb30@ipxe.org>
* [efi] Allow for non-image-backed virtual filesMichael Brown2021-05-211-69/+221
| | | | | | | | Restructure the EFI_SIMPLE_FILE_SYSTEM_PROTOCOL implementation to allow for the existence of virtual files that are not simply backed by a single underlying image. Signed-off-by: Michael Brown <mcb30@ipxe.org>
* [efi] Centralise EFI file system info GUIDsMichael Brown2015-12-091-6/+0Star
| | | | Signed-off-by: Michael Brown <mcb30@ipxe.org>
* [efi] Reset root directory when installing EFI_SIMPLE_FILE_SYSTEM_PROTOCOLMichael Brown2015-10-071-0/+3
| | | | Signed-off-by: Michael Brown <mcb30@ipxe.org>
* [legal] Relicense files under GPL2_OR_LATER_OR_UBDLMichael Brown2015-03-021-1/+5
| | | | | | | Relicense files for which I am the sole author (as identified by util/relicense.pl). Signed-off-by: Michael Brown <mcb30@ipxe.org>
* [efi] Make our virtual file system case insensitiveMichael Brown2014-08-271-4/+24
| | | | Signed-off-by: Michael Brown <mcb30@ipxe.org>
* [efi] Dump details of any calls to our dummy block and disk I/O protocolsMichael Brown2014-08-221-15/+33
| | | | Signed-off-by: Michael Brown <mcb30@ipxe.org>
* [efi] Provide centralised definitions of commonly-used GUIDsMichael Brown2014-08-061-12/+0Star
| | | | Signed-off-by: Michael Brown <mcb30@ipxe.org>
* [efi] Dump existing openers when we are unable to open a protocolMichael Brown2014-07-311-0/+1
| | | | | | | | Dump the existing openers of a protocol whenever we are unable to open a protocol using attributes of BY_DEVICE, EXCLUSIVE, or BY_CHILD_CONTROLLER. Signed-off-by: Michael Brown <mcb30@ipxe.org>
* [efi] Avoid unnecessarily passing pointers to EFI_HANDLEsMichael Brown2014-07-311-7/+7
| | | | | | | | | | | | efi_file_install() and efi_download_install() are both used to install onto existing handles. There is therefore no need to allow for each of their calls to InstallMultipleProtocolInterfaces() to create a new handle. By passing the handle directly (rather than a pointer to the handle), we avoid potential confusion (and erroneous debug message colours). Signed-off-by: Michael Brown <mcb30@ipxe.org>
* [efi] Install our own disk I/O protocol and claim exclusive use of itMichael Brown2014-07-141-13/+104
| | | | | | | | | | | | | | | | | | | The EFI FAT filesystem driver has a bug: if a block device contains no FAT filesystem but does have an EFI_SIMPLE_FILE_SYSTEM_PROTOCOL instance, the FAT driver will assume that it must have previously installed the EFI_SIMPLE_FILE_SYSTEM_PROTOCOL. This causes the FAT driver to claim control of our device, and to refuse to stop driving it, which prevents us from later uninstalling correctly. Work around this bug by opening the disk I/O protocol ourselves, thereby preventing the FAT driver from opening it. Note that the alternative approach of opening the block I/O protocol (and thereby in theory preventing DiskIo from attaching to the block I/O protocol) causes an endless loop of calls to our DRIVER_STOP method when starting the EFI shell. I have no idea why this is. Signed-off-by: Michael Brown <mcb30@ipxe.org>
* [efi] Perform meaningful error code conversionsMichael Brown2013-04-191-2/+5
| | | | | | | | Exploit the redefinition of iPXE error codes to include a "platform error code" to allow for meaningful conversion of EFI_STATUS values to iPXE errors and vice versa. Signed-off-by: Michael Brown <mcb30@ipxe.org>
* [efi] Provide efi_guid_ntoa() for printing EFI GUIDsMichael Brown2013-03-201-3/+2Star
| | | | Signed-off-by: Michael Brown <mcb30@ipxe.org>
* [efi] Expose downloaded images via EFI_SIMPLE_FILE_SYSTEM_PROTOCOLMichael Brown2013-03-131-0/+594
Expose iPXE's images as a UEFI file system, allowing the booted image to access all images downloaded by iPXE. This functionality is complementary to the custom iPXE download protocol. The iPXE download protocol allows a booted image to utilise iPXE to download arbitrary URIs, but requires the booted image to specifically support the custom iPXE download protocol. The new functionality limits the booted image to accessing only files that were already downloaded by iPXE (e.g. as part of a script), but can work with any generic UEFI image (e.g. the UEFI shell). Both protocols are provided simultaneously, and are attached to the SNP device handle. Signed-off-by: Michael Brown <mcb30@ipxe.org>