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138 lines
5.0 KiB
138 lines
5.0 KiB
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Javier Martinez Canillas <javierm@redhat.com>
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Date: Mon, 28 Sep 2020 20:08:33 +0200
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Subject: [PATCH] efi: Use grub_is_lockdown() instead of hardcoding a disabled
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modules list
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Now the GRUB can check if it has been locked down and this can be used to
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prevent executing commands that can be utilized to circumvent the UEFI
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Secure Boot mechanisms. So, instead of hardcoding a list of modules that
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have to be disabled, prevent the usage of commands that can be dangerous.
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This not only allows the commands to be disabled on other platforms, but
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also properly separate the concerns. Since the shim_lock verifier logic
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should be only about preventing to run untrusted binaries and not about
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defining these kind of policies.
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Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
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Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
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---
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grub-core/commands/iorw.c | 26 ++++++++++----------------
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grub-core/commands/memrw.c | 26 ++++++++++----------------
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2 files changed, 20 insertions(+), 32 deletions(-)
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diff --git a/grub-core/commands/iorw.c b/grub-core/commands/iorw.c
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index 41a7f3f04..584baec8f 100644
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--- a/grub-core/commands/iorw.c
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+++ b/grub-core/commands/iorw.c
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@@ -23,7 +23,7 @@
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#include <grub/env.h>
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#include <grub/cpu/io.h>
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#include <grub/i18n.h>
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-#include <grub/efi/sb.h>
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+#include <grub/lockdown.h>
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GRUB_MOD_LICENSE ("GPLv3+");
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@@ -119,9 +119,6 @@ grub_cmd_write (grub_command_t cmd, int argc, char **argv)
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GRUB_MOD_INIT(memrw)
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{
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- if (grub_efi_secure_boot())
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- return;
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-
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cmd_read_byte =
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grub_register_extcmd ("inb", grub_cmd_read, 0,
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N_("PORT"), N_("Read 8-bit value from PORT."),
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@@ -135,24 +132,21 @@ GRUB_MOD_INIT(memrw)
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N_("PORT"), N_("Read 32-bit value from PORT."),
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options);
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cmd_write_byte =
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- grub_register_command ("outb", grub_cmd_write,
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- N_("PORT VALUE [MASK]"),
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- N_("Write 8-bit VALUE to PORT."));
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+ grub_register_command_lockdown ("outb", grub_cmd_write,
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+ N_("PORT VALUE [MASK]"),
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+ N_("Write 8-bit VALUE to PORT."));
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cmd_write_word =
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- grub_register_command ("outw", grub_cmd_write,
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- N_("PORT VALUE [MASK]"),
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- N_("Write 16-bit VALUE to PORT."));
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+ grub_register_command_lockdown ("outw", grub_cmd_write,
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+ N_("PORT VALUE [MASK]"),
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+ N_("Write 16-bit VALUE to PORT."));
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cmd_write_dword =
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- grub_register_command ("outl", grub_cmd_write,
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- N_("ADDR VALUE [MASK]"),
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- N_("Write 32-bit VALUE to PORT."));
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+ grub_register_command_lockdown ("outl", grub_cmd_write,
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+ N_("ADDR VALUE [MASK]"),
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+ N_("Write 32-bit VALUE to PORT."));
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}
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GRUB_MOD_FINI(memrw)
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{
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- if (grub_efi_secure_boot())
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- return;
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-
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grub_unregister_extcmd (cmd_read_byte);
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grub_unregister_extcmd (cmd_read_word);
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grub_unregister_extcmd (cmd_read_dword);
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diff --git a/grub-core/commands/memrw.c b/grub-core/commands/memrw.c
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index 088cbe9e2..d401a6db0 100644
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--- a/grub-core/commands/memrw.c
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+++ b/grub-core/commands/memrw.c
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@@ -22,7 +22,7 @@
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#include <grub/extcmd.h>
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#include <grub/env.h>
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#include <grub/i18n.h>
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-#include <grub/efi/sb.h>
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+#include <grub/lockdown.h>
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GRUB_MOD_LICENSE ("GPLv3+");
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@@ -121,9 +121,6 @@ grub_cmd_write (grub_command_t cmd, int argc, char **argv)
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GRUB_MOD_INIT(memrw)
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{
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- if (grub_efi_secure_boot())
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- return;
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-
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cmd_read_byte =
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grub_register_extcmd ("read_byte", grub_cmd_read, 0,
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N_("ADDR"), N_("Read 8-bit value from ADDR."),
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@@ -137,24 +134,21 @@ GRUB_MOD_INIT(memrw)
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N_("ADDR"), N_("Read 32-bit value from ADDR."),
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options);
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cmd_write_byte =
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- grub_register_command ("write_byte", grub_cmd_write,
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- N_("ADDR VALUE [MASK]"),
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- N_("Write 8-bit VALUE to ADDR."));
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+ grub_register_command_lockdown ("write_byte", grub_cmd_write,
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+ N_("ADDR VALUE [MASK]"),
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+ N_("Write 8-bit VALUE to ADDR."));
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cmd_write_word =
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- grub_register_command ("write_word", grub_cmd_write,
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- N_("ADDR VALUE [MASK]"),
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- N_("Write 16-bit VALUE to ADDR."));
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+ grub_register_command_lockdown ("write_word", grub_cmd_write,
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+ N_("ADDR VALUE [MASK]"),
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+ N_("Write 16-bit VALUE to ADDR."));
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cmd_write_dword =
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- grub_register_command ("write_dword", grub_cmd_write,
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- N_("ADDR VALUE [MASK]"),
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- N_("Write 32-bit VALUE to ADDR."));
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+ grub_register_command_lockdown ("write_dword", grub_cmd_write,
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+ N_("ADDR VALUE [MASK]"),
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+ N_("Write 32-bit VALUE to ADDR."));
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}
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GRUB_MOD_FINI(memrw)
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{
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- if (grub_efi_secure_boot())
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- return;
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-
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grub_unregister_extcmd (cmd_read_byte);
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grub_unregister_extcmd (cmd_read_word);
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grub_unregister_extcmd (cmd_read_dword);
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