kernel/linux.git/include/linux/efi.h, branch v5.10.185

efi: random: combine bootloader provided RNG seed with RNG protocol output

2023-01-14T09:16:50+00:00

commit 196dff2712ca5a2e651977bb2fe6b05474111a83 upstream. Instead of blindly creating the EFI random seed configuration table if the RNG protocol is implemented and works, check whether such a EFI configuration table was provided by an earlier boot stage and if so, concatenate the existing and the new seeds, leaving it up to the core code to mix it in and credit it the way it sees fit. This can be used for, e.g., systemd-boot, to pass an additional seed to Linux in a way that can be consumed by the kernel very early. In that case, the following definitions should be used to pass the seed to the EFI stub: struct linux_efi_random_seed { u32 size; // of the 'seed' array in bytes u8 seed[]; }; The memory for the struct must be allocated as EFI_ACPI_RECLAIM_MEMORY pool memory, and the address of the struct in memory should be installed as a EFI configuration table using the following GUID: LINUX_EFI_RANDOM_SEED_TABLE_GUID 1ce1e5bc-7ceb-42f2-81e5-8aadf180f57b Note that doing so is safe even on kernels that were built without this patch applied, but the seed will simply be overwritten with a seed derived from the EFI RNG protocol, if available. The recommended seed size is 32 bytes, and seeds larger than 512 bytes are considered corrupted and ignored entirely. In order to preserve forward secrecy, seeds from previous bootloaders are memzero'd out, and in order to preserve memory, those older seeds are also freed from memory. Freeing from memory without first memzeroing is not safe to do, as it's possible that nothing else will ever overwrite those pages used by EFI. Reviewed-by: Jason A. Donenfeld [ardb: incorporate Jason's followup changes to extend the maximum seed size on the consumer end, memzero() it and drop a needless printk] Signed-off-by: Ard Biesheuvel Signed-off-by: Jason A. Donenfeld Signed-off-by: Greg Kroah-Hartman

efi: random: reduce seed size to 32 bytes

2022-11-10T17:14:27+00:00

commit 161a438d730dade2ba2b1bf8785f0759aba4ca5f upstream. We no longer need at least 64 bytes of random seed to permit the early crng init to complete. The RNG is now based on Blake2s, so reduce the EFI seed size to the Blake2s hash size, which is sufficient for our purposes. While at it, drop the READ_ONCE(), which was supposed to prevent size from being evaluated after seed was unmapped. However, this cannot actually happen, so READ_ONCE() is unnecessary here. Cc: # v4.14+ Signed-off-by: Ard Biesheuvel Reviewed-by: Jason A. Donenfeld Acked-by: Ilias Apalodimas Signed-off-by: Greg Kroah-Hartman

efi: Add missing prototype for efi_capsule_setup_info

2022-06-09T08:21:01+00:00

[ Upstream commit aa480379d8bdb33920d68acfd90f823c8af32578 ] Fixes "no previous declaration for 'efi_capsule_setup_info'" warnings under W=1. Fixes: 2959c95d510c ("efi/capsule: Add support for Quark security header") Signed-off-by: Jan Kiszka Link: https://lore.kernel.org/r/c28d3f86-dd72-27d1-e2c2-40971b8da6bd@siemens.com Signed-off-by: Ard Biesheuvel Signed-off-by: Sasha Levin

efi: use 32-bit alignment for efi_guid_t literals

2021-03-25T08:04:18+00:00

commit fb98cc0b3af2ba4d87301dff2b381b12eee35d7d upstream. Commit 494c704f9af0 ("efi: Use 32-bit alignment for efi_guid_t") updated the type definition of efi_guid_t to ensure that it always appears sufficiently aligned (the UEFI spec is ambiguous about this, but given the fact that its EFI_GUID type is defined in terms of a struct carrying a uint32_t, the natural alignment is definitely >= 32 bits). However, we missed the EFI_GUID() macro which is used to instantiate efi_guid_t literals: that macro is still based on the guid_t type, which does not have a minimum alignment at all. This results in warnings such as In file included from drivers/firmware/efi/mokvar-table.c:35: include/linux/efi.h:1093:34: warning: passing 1-byte aligned argument to 4-byte aligned parameter 2 of 'get_var' may result in an unaligned pointer access [-Walign-mismatch] status = get_var(L"SecureBoot", &EFI_GLOBAL_VARIABLE_GUID, NULL, &size, ^ include/linux/efi.h:1101:24: warning: passing 1-byte aligned argument to 4-byte aligned parameter 2 of 'get_var' may result in an unaligned pointer access [-Walign-mismatch] get_var(L"SetupMode", &EFI_GLOBAL_VARIABLE_GUID, NULL, &size, &setupmode); The distinction only matters on CPUs that do not support misaligned loads fully, but 32-bit ARM's load-multiple instructions fall into that category, and these are likely to be emitted by the compiler that built the firmware for loading word-aligned 128-bit GUIDs from memory So re-implement the initializer in terms of our own efi_guid_t type, so that the alignment becomes a property of the literal's type. Fixes: 494c704f9af0 ("efi: Use 32-bit alignment for efi_guid_t") Reported-by: Nathan Chancellor Reviewed-by: Nick Desaulniers Reviewed-by: Nathan Chancellor Tested-by: Nathan Chancellor Link: https://github.com/ClangBuiltLinux/linux/issues/1327 Signed-off-by: Ard Biesheuvel Signed-off-by: Greg Kroah-Hartman

Merge branch 'efi/urgent' into efi/core, to pick up fixes

2020-10-12T11:38:31+00:00

These fixes missed the v5.9 merge window, pick them up for early v5.10 merge. Signed-off-by: Ingo Molnar

efi: efivars: un-export efivars_sysfs_init()

2020-09-29T17:40:57+00:00

efivars_sysfs_init() is only used locally in the source file that defines it, so make it static and unexport it. Signed-off-by: Ard Biesheuvel

efi: pstore: move workqueue handling out of efivars

2020-09-29T17:40:57+00:00

The worker thread that gets kicked off to sync the state of the EFI variable list is only used by the EFI pstore implementation, and is defined in its source file. So let's move its scheduling there as well. Since our efivar_init() scan will bail on duplicate entries, there is no need to disable the workqueue like we did before, so we can run it unconditionally. Signed-off-by: Ard Biesheuvel

efi: pstore: disentangle from deprecated efivars module

2020-09-29T17:40:57+00:00

The EFI pstore implementation relies on the 'efivars' abstraction, which encapsulates the EFI variable store in a way that can be overridden by other backing stores, like the Google SMI one. On top of that, the EFI pstore implementation also relies on the efivars.ko module, which is a separate layer built on top of the 'efivars' abstraction that exposes the [deprecated] sysfs entries for each variable that exists in the backing store. Since the efivars.ko module is deprecated, and all users appear to have moved to the efivarfs file system instead, let's prepare for its removal, by removing EFI pstore's dependency on it. Signed-off-by: Ard Biesheuvel

efi: Add definition of EFI_MEMORY_CPU_CRYPTO and ability to report it

2020-09-25T21:29:04+00:00

Incorporate the definition of EFI_MEMORY_CPU_CRYPTO from the UEFI specification v2.8, and wire it into our memory map dumping routine as well. To make a bit of space in the output buffer, which is provided by the various callers, shorten the descriptive names of the memory types. Reviewed-by: Laszlo Ersek Signed-off-by: Ard Biesheuvel

efi: Support for MOK variable config table

2020-09-16T15:53:42+00:00

Because of system-specific EFI firmware limitations, EFI volatile variables may not be capable of holding the required contents of the Machine Owner Key (MOK) certificate store when the certificate list grows above some size. Therefore, an EFI boot loader may pass the MOK certs via a EFI configuration table created specifically for this purpose to avoid this firmware limitation. An EFI configuration table is a much more primitive mechanism compared to EFI variables and is well suited for one-way passage of static information from a pre-OS environment to the kernel. This patch adds initial kernel support to recognize, parse, and validate the EFI MOK configuration table, where named entries contain the same data that would otherwise be provided in similarly named EFI variables. Additionally, this patch creates a sysfs binary file for each EFI MOK configuration table entry found. These files are read-only to root and are provided for use by user space utilities such as mokutil. A subsequent patch will load MOK certs into the trusted platform key ring using this infrastructure. Signed-off-by: Lenny Szubowicz Link: https://lore.kernel.org/r/20200905013107.10457-2-lszubowi@redhat.com Signed-off-by: Ard Biesheuvel