diff options
Diffstat (limited to 'debian/patches/cve_2022_2601/0009-kern-efi-sb-Enforce-verification-of-font-files.patch')
| -rw-r--r-- | debian/patches/cve_2022_2601/0009-kern-efi-sb-Enforce-verification-of-font-files.patch | 54 |
1 files changed, 54 insertions, 0 deletions
diff --git a/debian/patches/cve_2022_2601/0009-kern-efi-sb-Enforce-verification-of-font-files.patch b/debian/patches/cve_2022_2601/0009-kern-efi-sb-Enforce-verification-of-font-files.patch new file mode 100644 index 0000000..705835a --- /dev/null +++ b/debian/patches/cve_2022_2601/0009-kern-efi-sb-Enforce-verification-of-font-files.patch @@ -0,0 +1,54 @@ +From 630deb8c0d8b02b670ced4b7030414bcf17aa080 Mon Sep 17 00:00:00 2001 +From: Zhang Boyang <zhangboyang.id@gmail.com> +Date: Sun, 14 Aug 2022 15:51:54 +0800 +Subject: [PATCH 09/14] kern/efi/sb: Enforce verification of font files + +As a mitigation and hardening measure enforce verification of font +files. Then only trusted font files can be load. This will reduce the +attack surface at cost of losing the ability of end-users to customize +fonts if e.g. UEFI Secure Boot is enabled. Vendors can always customize +fonts because they have ability to pack fonts into their GRUB bundles. + +This goal is achieved by: + + * Removing GRUB_FILE_TYPE_FONT from shim lock verifier's + skip-verification list. + + * Adding GRUB_FILE_TYPE_FONT to lockdown verifier's defer-auth list, + so font files must be verified by a verifier before they can be loaded. + +Suggested-by: Daniel Kiper <daniel.kiper@oracle.com> +Signed-off-by: Zhang Boyang <zhangboyang.id@gmail.com> +Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com> +--- + grub-core/kern/efi/sb.c | 1 - + grub-core/kern/lockdown.c | 1 + + 2 files changed, 1 insertion(+), 1 deletion(-) + +diff --git a/grub-core/kern/efi/sb.c b/grub-core/kern/efi/sb.c +index 89c4bb3fd..db42c2539 100644 +--- a/grub-core/kern/efi/sb.c ++++ b/grub-core/kern/efi/sb.c +@@ -145,7 +145,6 @@ shim_lock_verifier_init (grub_file_t io __attribute__ ((unused)), + case GRUB_FILE_TYPE_PRINT_BLOCKLIST: + case GRUB_FILE_TYPE_TESTLOAD: + case GRUB_FILE_TYPE_GET_SIZE: +- case GRUB_FILE_TYPE_FONT: + case GRUB_FILE_TYPE_ZFS_ENCRYPTION_KEY: + case GRUB_FILE_TYPE_CAT: + case GRUB_FILE_TYPE_HEXCAT: +diff --git a/grub-core/kern/lockdown.c b/grub-core/kern/lockdown.c +index 0bc70fd42..af6d493cd 100644 +--- a/grub-core/kern/lockdown.c ++++ b/grub-core/kern/lockdown.c +@@ -51,6 +51,7 @@ lockdown_verifier_init (grub_file_t io __attribute__ ((unused)), + case GRUB_FILE_TYPE_EFI_CHAINLOADED_IMAGE: + case GRUB_FILE_TYPE_ACPI_TABLE: + case GRUB_FILE_TYPE_DEVICE_TREE_IMAGE: ++ case GRUB_FILE_TYPE_FONT: + *flags = GRUB_VERIFY_FLAGS_DEFER_AUTH; + + /* Fall through. */ +-- +2.30.2 + |