41 lines
1.5 KiB
Diff
41 lines
1.5 KiB
Diff
From: Linn Crosetto <linn@hpe.com>
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Date: Wed, 8 Nov 2017 15:11:34 +0000
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Subject: [17/29] acpi: Disable ACPI table override if the kernel is locked
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down
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Origin: https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git/commit?id=5976d26de05569951641ebeb95f7240993b66063
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From the kernel documentation (initrd_table_override.txt):
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If the ACPI_INITRD_TABLE_OVERRIDE compile option is true, it is possible
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to override nearly any ACPI table provided by the BIOS with an
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instrumented, modified one.
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When securelevel is set, the kernel should disallow any unauthenticated
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changes to kernel space. ACPI tables contain code invoked by the kernel,
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so do not allow ACPI tables to be overridden if the kernel is locked down.
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Signed-off-by: Linn Crosetto <linn@hpe.com>
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Signed-off-by: David Howells <dhowells@redhat.com>
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Reviewed-by: "Lee, Chun-Yi" <jlee@suse.com>
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cc: linux-acpi@vger.kernel.org
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---
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drivers/acpi/tables.c | 5 +++++
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1 file changed, 5 insertions(+)
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Index: linux/drivers/acpi/tables.c
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===================================================================
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--- linux.orig/drivers/acpi/tables.c
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+++ linux/drivers/acpi/tables.c
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@@ -532,6 +532,11 @@ void __init acpi_table_upgrade(void)
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if (table_nr == 0)
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return;
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+ if (kernel_is_locked_down("ACPI table override")) {
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+ pr_notice("kernel is locked down, ignoring table override\n");
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+ return;
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+ }
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+
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acpi_tables_addr =
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memblock_find_in_range(0, ACPI_TABLE_UPGRADE_MAX_PHYS,
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all_tables_size, PAGE_SIZE);
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