216 lines
6.3 KiB
Diff
216 lines
6.3 KiB
Diff
From 8802c7e62531b3867580068ee8b50415b966d22c Mon Sep 17 00:00:00 2001
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From: Matthew Garrett <matthew.garrett@nebula.com>
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Date: Fri, 9 Aug 2013 18:36:30 -0400
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Subject: [PATCH 10/20] Add option to automatically enforce module signatures when in Secure Boot mode
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UEFI Secure Boot provides a mechanism for ensuring that the firmware will
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only load signed bootloaders and kernels. Certain use cases may also
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require that all kernel modules also be signed. Add a configuration option
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that enforces this automatically when enabled.
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Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>
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---
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Documentation/x86/zero-page.txt | 2 ++
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arch/x86/Kconfig | 10 ++++++
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arch/x86/boot/compressed/eboot.c | 66 +++++++++++++++++++++++++++++++++++
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arch/x86/include/uapi/asm/bootparam.h | 3 +-
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arch/x86/kernel/setup.c | 6 ++++
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include/linux/module.h | 6 ++++
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kernel/module.c | 7 ++++
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7 files changed, 99 insertions(+), 1 deletion(-)
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diff --git a/Documentation/x86/zero-page.txt b/Documentation/x86/zero-page.txt
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index 95a4d34..b8527c6 100644
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--- a/Documentation/x86/zero-page.txt
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+++ b/Documentation/x86/zero-page.txt
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@@ -31,6 +31,8 @@ Offset Proto Name Meaning
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1E9/001 ALL eddbuf_entries Number of entries in eddbuf (below)
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1EA/001 ALL edd_mbr_sig_buf_entries Number of entries in edd_mbr_sig_buffer
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(below)
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+1EB/001 ALL kbd_status Numlock is enabled
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+1EC/001 ALL secure_boot Secure boot is enabled in the firmware
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1EF/001 ALL sentinel Used to detect broken bootloaders
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290/040 ALL edd_mbr_sig_buffer EDD MBR signatures
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2D0/A00 ALL e820_map E820 memory map table
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diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
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index 2dc18605..a701d09 100644
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--- a/arch/x86/Kconfig
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+++ b/arch/x86/Kconfig
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@@ -1785,6 +1785,16 @@ config EFI_MIXED
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If unsure, say N.
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+config EFI_SECURE_BOOT_SIG_ENFORCE
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+ def_bool n
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+ prompt "Force module signing when UEFI Secure Boot is enabled"
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+ ---help---
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+ UEFI Secure Boot provides a mechanism for ensuring that the
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+ firmware will only load signed bootloaders and kernels. Certain
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+ use cases may also require that all kernel modules also be signed.
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+ Say Y here to automatically enable module signature enforcement
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+ when a system boots with UEFI Secure Boot enabled.
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+
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config SECCOMP
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def_bool y
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prompt "Enable seccomp to safely compute untrusted bytecode"
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diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c
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index 52fef60..6b8b9a7 100644
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--- a/arch/x86/boot/compressed/eboot.c
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+++ b/arch/x86/boot/compressed/eboot.c
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@@ -12,6 +12,7 @@
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#include <asm/efi.h>
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#include <asm/setup.h>
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#include <asm/desc.h>
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+#include <asm/bootparam_utils.h>
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#include "../string.h"
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#include "eboot.h"
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@@ -571,6 +572,67 @@ free_handle:
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efi_call_early(free_pool, pci_handle);
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}
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+static int get_secure_boot(void)
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+{
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+ u8 sb, setup;
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+ unsigned long datasize = sizeof(sb);
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+ efi_guid_t var_guid = EFI_GLOBAL_VARIABLE_GUID;
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+ efi_status_t status;
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+
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+ status = efi_early->call((unsigned long)sys_table->runtime->get_variable,
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+ L"SecureBoot", &var_guid, NULL, &datasize, &sb);
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+
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+ if (status != EFI_SUCCESS)
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+ return 0;
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+
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+ if (sb == 0)
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+ return 0;
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+
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+
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+ status = efi_early->call((unsigned long)sys_table->runtime->get_variable,
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+ L"SetupMode", &var_guid, NULL, &datasize,
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+ &setup);
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+
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+ if (status != EFI_SUCCESS)
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+ return 0;
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+
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+ if (setup == 1)
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+ return 0;
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+
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+ return 1;
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+}
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+
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+
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+/*
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+ * See if we have Graphics Output Protocol
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+ */
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+static efi_status_t setup_gop(struct screen_info *si, efi_guid_t *proto,
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+ unsigned long size)
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+{
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+ efi_status_t status;
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+ void **gop_handle = NULL;
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+
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+ status = efi_call_early(allocate_pool, EFI_LOADER_DATA,
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+ size, (void **)&gop_handle);
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+ if (status != EFI_SUCCESS)
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+ return status;
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+
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+ status = efi_call_early(locate_handle,
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+ EFI_LOCATE_BY_PROTOCOL,
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+ proto, NULL, &size, gop_handle);
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+ if (status != EFI_SUCCESS)
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+ goto free_handle;
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+
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+ if (efi_early->is64)
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+ status = setup_gop64(si, proto, size, gop_handle);
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+ else
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+ status = setup_gop32(si, proto, size, gop_handle);
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+
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+free_handle:
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+ efi_call_early(free_pool, gop_handle);
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+ return status;
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+}
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+
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static efi_status_t
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setup_uga32(void **uga_handle, unsigned long size, u32 *width, u32 *height)
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{
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@@ -1126,6 +1188,10 @@ struct boot_params *efi_main(struct efi_config *c,
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else
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setup_boot_services32(efi_early);
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+ sanitize_boot_params(boot_params);
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+
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+ boot_params->secure_boot = get_secure_boot();
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+
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setup_graphics(boot_params);
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setup_efi_pci(boot_params);
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diff --git a/arch/x86/include/uapi/asm/bootparam.h b/arch/x86/include/uapi/asm/bootparam.h
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index 3292543..b61f853 100644
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--- a/arch/x86/include/uapi/asm/bootparam.h
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+++ b/arch/x86/include/uapi/asm/bootparam.h
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@@ -134,7 +134,8 @@ struct boot_params {
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__u8 eddbuf_entries; /* 0x1e9 */
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__u8 edd_mbr_sig_buf_entries; /* 0x1ea */
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__u8 kbd_status; /* 0x1eb */
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- __u8 _pad5[3]; /* 0x1ec */
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+ __u8 secure_boot; /* 0x1ec */
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+ __u8 _pad5[2]; /* 0x1ed */
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/*
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* The sentinel is set to a nonzero value (0xff) in header.S.
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*
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diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
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index 2367ae0..1a78bf7 100644
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--- a/arch/x86/kernel/setup.c
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+++ b/arch/x86/kernel/setup.c
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@@ -1146,6 +1146,12 @@ void __init setup_arch(char **cmdline_p)
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io_delay_init();
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+#ifdef CONFIG_EFI_SECURE_BOOT_SIG_ENFORCE
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+ if (boot_params.secure_boot) {
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+ enforce_signed_modules();
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+ }
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+#endif
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+
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/*
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* Parse the ACPI tables for possible boot-time SMP configuration.
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*/
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diff --git a/include/linux/module.h b/include/linux/module.h
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index ab13009..e072b84 100644
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--- a/include/linux/module.h
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+++ b/include/linux/module.h
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@@ -273,6 +273,12 @@ const struct exception_table_entry *search_exception_tables(unsigned long add);
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struct notifier_block;
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+#ifdef CONFIG_MODULE_SIG
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+extern void enforce_signed_modules(void);
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+#else
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+static inline void enforce_signed_modules(void) {};
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+#endif
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+
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#ifdef CONFIG_MODULES
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extern int modules_disabled; /* for sysctl */
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diff --git a/kernel/module.c b/kernel/module.c
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index 392ac8c..676c578 100644
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--- a/kernel/module.c
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+++ b/kernel/module.c
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@@ -4081,6 +4081,13 @@ void module_layout(struct module *mod,
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EXPORT_SYMBOL(module_layout);
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#endif
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+#ifdef CONFIG_MODULE_SIG
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+void enforce_signed_modules(void)
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+{
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+ sig_enforce = true;
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+}
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+#endif
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+
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bool secure_modules(void)
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{
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#ifdef CONFIG_MODULE_SIG
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--
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2.5.5
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