58 lines
2.1 KiB
Diff
58 lines
2.1 KiB
Diff
From 93a786a00163e50c29f0394df198518617e1c9a5 Mon Sep 17 00:00:00 2001
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From: Zhang Boyang <zhangboyang.id@gmail.com>
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Date: Sun, 14 Aug 2022 15:51:54 +0800
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Subject: [PATCH 08/13] kern/efi/sb: Enforce verification of font files
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As a mitigation and hardening measure enforce verification of font
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files. Then only trusted font files can be load. This will reduce the
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attack surface at cost of losing the ability of end-users to customize
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fonts if e.g. UEFI Secure Boot is enabled. Vendors can always customize
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fonts because they have ability to pack fonts into their GRUB bundles.
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This goal is achieved by:
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* Removing GRUB_FILE_TYPE_FONT from shim lock verifier's
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skip-verification list.
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* Adding GRUB_FILE_TYPE_FONT to lockdown verifier's defer-auth list,
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so font files must be verified by a verifier before they can be
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loaded.
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Conflict:grub-core/kern/efi/sb.c -> grub-core/commands/efi/shim_lock.c
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Suggested-by: Daniel Kiper <daniel.kiper@oracle.com>
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Signed-off-by: Zhang Boyang <zhangboyang.id@gmail.com>
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Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
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---
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grub-core/commands/efi/shim_lock.c | 1 +
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grub-core/kern/lockdown.c | 1 +
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2 files changed, 2 insertions(+)
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diff --git a/grub-core/commands/efi/shim_lock.c b/grub-core/commands/efi/shim_lock.c
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index 764098c..42f088a 100644
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--- a/grub-core/commands/efi/shim_lock.c
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+++ b/grub-core/commands/efi/shim_lock.c
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@@ -82,6 +82,7 @@ shim_lock_init (grub_file_t io, enum grub_file_type type,
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case GRUB_FILE_TYPE_ACPI_TABLE:
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case GRUB_FILE_TYPE_DEVICE_TREE_IMAGE:
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+ case GRUB_FILE_TYPE_FONT:
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*flags = GRUB_VERIFY_FLAGS_DEFER_AUTH;
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return GRUB_ERR_NONE;
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diff --git a/grub-core/kern/lockdown.c b/grub-core/kern/lockdown.c
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index 0bc70fd..af6d493 100644
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--- a/grub-core/kern/lockdown.c
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+++ b/grub-core/kern/lockdown.c
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@@ -51,6 +51,7 @@ lockdown_verifier_init (grub_file_t io __attribute__ ((unused)),
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case GRUB_FILE_TYPE_EFI_CHAINLOADED_IMAGE:
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case GRUB_FILE_TYPE_ACPI_TABLE:
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case GRUB_FILE_TYPE_DEVICE_TREE_IMAGE:
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+ case GRUB_FILE_TYPE_FONT:
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*flags = GRUB_VERIFY_FLAGS_DEFER_AUTH;
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/* Fall through. */
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--
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2.27.0
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