tleleu / rpms / kernel

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From 478a0cff698409224330ea9e25eb332220b55dbb Mon Sep 17 00:00:00 2001
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From: Jeremy Cline <jcline@redhat.com>
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Date: Mon, 30 Sep 2019 21:22:47 +0000
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Subject: [PATCH 1/3] security: lockdown: expose a hook to lock the kernel down
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In order to automatically lock down kernels running on UEFI machines
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booted in Secure Boot mode, expose the lock_kernel_down() hook.
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Signed-off-by: Jeremy Cline <jcline@redhat.com>
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---
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 include/linux/lsm_hooks.h    | 8 ++++++++
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 include/linux/security.h     | 5 +++++
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 security/lockdown/lockdown.c | 1 +
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 security/security.c          | 6 ++++++
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 4 files changed, 20 insertions(+)
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diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
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index a3763247547c..8d76d1f153ed 100644
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--- a/include/linux/lsm_hooks.h
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+++ b/include/linux/lsm_hooks.h
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@@ -1454,6 +1454,12 @@
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  *     code execution in kernel space should be permitted.
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  *
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  *     @what: kernel feature being accessed
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+ *
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+ * @lock_kernel_down
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+ *     Put the kernel into lock-down mode.
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+ *
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+ *     @where: Where the lock-down is originating from (e.g. command line option)
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+ *     @level: The lock-down level (can only increase)
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  */
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 union security_list_options {
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 	int (*binder_set_context_mgr)(struct task_struct *mgr);
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@@ -1818,6 +1824,7 @@ union security_list_options {
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 	void (*bpf_prog_free_security)(struct bpf_prog_aux *aux);
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 #endif /* CONFIG_BPF_SYSCALL */
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 	int (*locked_down)(enum lockdown_reason what);
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+	int (*lock_kernel_down)(const char *where, enum lockdown_reason level);
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 };
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 struct security_hook_heads {
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@@ -2060,6 +2067,7 @@ struct security_hook_heads {
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 	struct hlist_head bpf_prog_free_security;
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 #endif /* CONFIG_BPF_SYSCALL */
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 	struct hlist_head locked_down;
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+	struct hlist_head lock_kernel_down;
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 } __randomize_layout;
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 /*
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diff --git a/include/linux/security.h b/include/linux/security.h
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index a8d59d612d27..467b9ccdf993 100644
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--- a/include/linux/security.h
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+++ b/include/linux/security.h
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@@ -442,6 +442,7 @@ int security_inode_notifysecctx(struct inode *inode, void *ctx, u32 ctxlen);
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 int security_inode_setsecctx(struct dentry *dentry, void *ctx, u32 ctxlen);
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 int security_inode_getsecctx(struct inode *inode, void **ctx, u32 *ctxlen);
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 int security_locked_down(enum lockdown_reason what);
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+int security_lock_kernel_down(const char *where, enum lockdown_reason level);
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 #else /* CONFIG_SECURITY */
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 static inline int call_blocking_lsm_notifier(enum lsm_event event, void *data)
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@@ -1269,6 +1270,10 @@ static inline int security_locked_down(enum lockdown_reason what)
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 {
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 	return 0;
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 }
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+static inline int security_lock_kernel_down(const char *where, enum lockdown_reason level)
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+{
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+	return 0;
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+}
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 #endif	/* CONFIG_SECURITY */
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 #ifdef CONFIG_SECURITY_NETWORK
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diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
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index 8a10b43daf74..72a623075749 100644
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--- a/security/lockdown/lockdown.c
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+++ b/security/lockdown/lockdown.c
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@@ -97,6 +97,7 @@ static int lockdown_is_locked_down(enum lockdown_reason what)
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 static struct security_hook_list lockdown_hooks[] __lsm_ro_after_init = {
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 	LSM_HOOK_INIT(locked_down, lockdown_is_locked_down),
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+	LSM_HOOK_INIT(lock_kernel_down, lock_kernel_down),
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 };
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 static int __init lockdown_lsm_init(void)
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diff --git a/security/security.c b/security/security.c
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index 1bc000f834e2..1506b95427cf 100644
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--- a/security/security.c
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+++ b/security/security.c
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@@ -2404,3 +2404,9 @@ int security_locked_down(enum lockdown_reason what)
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 	return call_int_hook(locked_down, 0, what);
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 }
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 EXPORT_SYMBOL(security_locked_down);
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+
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+int security_lock_kernel_down(const char *where, enum lockdown_reason level)
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+{
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+	return call_int_hook(lock_kernel_down, 0, where, level);
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+}
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+EXPORT_SYMBOL(security_lock_kernel_down);
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-- 
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2.21.0
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From b5123d0553f4ed5e734f6457696cdd30228d1eee Mon Sep 17 00:00:00 2001
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From: David Howells <dhowells@redhat.com>
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Date: Tue, 27 Feb 2018 10:04:55 +0000
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Subject: [PATCH 2/3] efi: Add an EFI_SECURE_BOOT flag to indicate secure
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 boot mode
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UEFI machines can be booted in Secure Boot mode.  Add an EFI_SECURE_BOOT
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flag that can be passed to efi_enabled() to find out whether secure boot is
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enabled.
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Move the switch-statement in x86's setup_arch() that inteprets the
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secure_boot boot parameter to generic code and set the bit there.
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Suggested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
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Signed-off-by: David Howells <dhowells@redhat.com>
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Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
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cc: linux-efi@vger.kernel.org
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[Rebased for context; efi_is_table_address was moved to arch/x86]
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Signed-off-by: Jeremy Cline <jcline@redhat.com>
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---
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 arch/x86/kernel/setup.c           | 14 +-----------
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 drivers/firmware/efi/Makefile     |  1 +
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 drivers/firmware/efi/secureboot.c | 38 +++++++++++++++++++++++++++++++
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 include/linux/efi.h               | 18 ++++++++++-----
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 4 files changed, 52 insertions(+), 19 deletions(-)
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 create mode 100644 drivers/firmware/efi/secureboot.c
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diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
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index bbe35bf879f5..7e528b6af86b 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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@@ -1179,19 +1179,7 @@ void __init setup_arch(char **cmdline_p)
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 	/* Allocate bigger log buffer */
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 	setup_log_buf(1);
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-	if (efi_enabled(EFI_BOOT)) {
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-		switch (boot_params.secure_boot) {
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-		case efi_secureboot_mode_disabled:
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-			pr_info("Secure boot disabled\n");
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-			break;
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-		case efi_secureboot_mode_enabled:
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-			pr_info("Secure boot enabled\n");
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-			break;
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-		default:
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-			pr_info("Secure boot could not be determined\n");
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-			break;
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-		}
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-	}
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+	efi_set_secure_boot(boot_params.secure_boot);
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 	reserve_initrd();
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diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile
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index 4ac2de4dfa72..195b078a423c 100644
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--- a/drivers/firmware/efi/Makefile
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+++ b/drivers/firmware/efi/Makefile
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@@ -24,6 +24,7 @@ obj-$(CONFIG_EFI_FAKE_MEMMAP)		+= fake_mem.o
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 obj-$(CONFIG_EFI_BOOTLOADER_CONTROL)	+= efibc.o
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 obj-$(CONFIG_EFI_TEST)			+= test/
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 obj-$(CONFIG_EFI_DEV_PATH_PARSER)	+= dev-path-parser.o
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+obj-$(CONFIG_EFI)			+= secureboot.o
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 obj-$(CONFIG_APPLE_PROPERTIES)		+= apple-properties.o
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 obj-$(CONFIG_EFI_RCI2_TABLE)		+= rci2-table.o
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diff --git a/drivers/firmware/efi/secureboot.c b/drivers/firmware/efi/secureboot.c
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new file mode 100644
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index 000000000000..9070055de0a1
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--- /dev/null
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+++ b/drivers/firmware/efi/secureboot.c
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@@ -0,0 +1,38 @@
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+/* Core kernel secure boot support.
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+ *
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+ * Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
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+ * Written by David Howells (dhowells@redhat.com)
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+ *
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+ * This program is free software; you can redistribute it and/or
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+ * modify it under the terms of the GNU General Public Licence
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+ * as published by the Free Software Foundation; either version
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+ * 2 of the Licence, or (at your option) any later version.
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+ */
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+
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+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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+
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+#include <linux/efi.h>
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+#include <linux/kernel.h>
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+#include <linux/printk.h>
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+
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+/*
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+ * Decide what to do when UEFI secure boot mode is enabled.
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+ */
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+void __init efi_set_secure_boot(enum efi_secureboot_mode mode)
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+{
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+	if (efi_enabled(EFI_BOOT)) {
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+		switch (mode) {
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+		case efi_secureboot_mode_disabled:
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+			pr_info("Secure boot disabled\n");
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+			break;
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+		case efi_secureboot_mode_enabled:
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+			set_bit(EFI_SECURE_BOOT, &efi.flags);
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+			pr_info("Secure boot enabled\n");
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+			break;
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+		default:
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+			pr_warning("Secure boot could not be determined (mode %u)\n",
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+				   mode);
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+			break;
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+		}
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+	}
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+}
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diff --git a/include/linux/efi.h b/include/linux/efi.h
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index 21d81021c1f4..758ec061d03b 100644
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--- a/include/linux/efi.h
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+++ b/include/linux/efi.h
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@@ -1204,6 +1204,14 @@ extern int __init efi_setup_pcdp_console(char *);
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 #define EFI_DBG			8	/* Print additional debug info at runtime */
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 #define EFI_NX_PE_DATA		9	/* Can runtime data regions be mapped non-executable? */
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 #define EFI_MEM_ATTR		10	/* Did firmware publish an EFI_MEMORY_ATTRIBUTES table? */
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+#define EFI_SECURE_BOOT		11	/* Are we in Secure Boot mode? */
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+
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+enum efi_secureboot_mode {
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+	efi_secureboot_mode_unset,
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+	efi_secureboot_mode_unknown,
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+	efi_secureboot_mode_disabled,
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+	efi_secureboot_mode_enabled,
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+};
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 #ifdef CONFIG_EFI
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 /*
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@@ -1214,6 +1222,8 @@ static inline bool efi_enabled(int feature)
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 	return test_bit(feature, &efi.flags) != 0;
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 }
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 extern void efi_reboot(enum reboot_mode reboot_mode, const char *__unused);
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+
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+extern void __init efi_set_secure_boot(enum efi_secureboot_mode mode);
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 #else
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 static inline bool efi_enabled(int feature)
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 {
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@@ -1227,6 +1237,8 @@ efi_capsule_pending(int *reset_type)
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 {
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 	return false;
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 }
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+
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+static inline void efi_set_secure_boot(enum efi_secureboot_mode mode) {}
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 #endif
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 extern int efi_status_to_err(efi_status_t status);
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@@ -1619,12 +1631,6 @@ static inline bool efi_runtime_disabled(void) { return true; }
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 extern void efi_call_virt_check_flags(unsigned long flags, const char *call);
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 extern unsigned long efi_call_virt_save_flags(void);
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-enum efi_secureboot_mode {
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-	efi_secureboot_mode_unset,
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-	efi_secureboot_mode_unknown,
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-	efi_secureboot_mode_disabled,
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-	efi_secureboot_mode_enabled,
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-};
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 enum efi_secureboot_mode efi_get_secureboot(efi_system_table_t *sys_table);
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 #ifdef CONFIG_RESET_ATTACK_MITIGATION
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-- 
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2.21.0
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From 15368f76d4997912318d35c52bfeb9041d85098e Mon Sep 17 00:00:00 2001
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From: David Howells <dhowells@redhat.com>
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Date: Mon, 30 Sep 2019 21:28:16 +0000
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Subject: [PATCH 3/3] efi: Lock down the kernel if booted in secure boot mode
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UEFI Secure Boot provides a mechanism for ensuring that the firmware
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will only load signed bootloaders and kernels.  Certain use cases may
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also require that all kernel modules also be signed.  Add a
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configuration option that to lock down the kernel - which includes
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requiring validly signed modules - if the kernel is secure-booted.
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Signed-off-by: David Howells <dhowells@redhat.com>
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Signed-off-by: Jeremy Cline <jcline@redhat.com>
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---
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 arch/x86/kernel/setup.c   |  8 ++++++++
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 security/lockdown/Kconfig | 13 +++++++++++++
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 2 files changed, 21 insertions(+)
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diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
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index 77ea96b794bd..a119e1bc9623 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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@@ -73,6 +73,7 @@
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 #include <linux/jiffies.h>
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 #include <linux/mem_encrypt.h>
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 #include <linux/sizes.h>
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+#include <linux/security.h>
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 #include <linux/usb/xhci-dbgp.h>
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 #include <video/edid.h>
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@@ -1027,6 +1028,13 @@ void __init setup_arch(char **cmdline_p)
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 	if (efi_enabled(EFI_BOOT))
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 		efi_init();
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+	efi_set_secure_boot(boot_params.secure_boot);
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+
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+#ifdef CONFIG_LOCK_DOWN_IN_EFI_SECURE_BOOT
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+	if (efi_enabled(EFI_SECURE_BOOT))
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+		security_lock_kernel_down("EFI Secure Boot mode", LOCKDOWN_CONFIDENTIALITY_MAX);
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+#endif
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+
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 	dmi_setup();
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 	/*
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diff --git a/security/lockdown/Kconfig b/security/lockdown/Kconfig
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index e84ddf484010..d0501353a4b9 100644
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--- a/security/lockdown/Kconfig
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+++ b/security/lockdown/Kconfig
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@@ -16,6 +16,19 @@ config SECURITY_LOCKDOWN_LSM_EARLY
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 	  subsystem is fully initialised. If enabled, lockdown will
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 	  unconditionally be called before any other LSMs.
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+config LOCK_DOWN_IN_EFI_SECURE_BOOT
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+	bool "Lock down the kernel in EFI Secure Boot mode"
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+	default n
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+	depends on EFI && SECURITY_LOCKDOWN_LSM_EARLY
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+	help
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+	  UEFI Secure Boot provides a mechanism for ensuring that the firmware
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+	  will only load signed bootloaders and kernels.  Secure boot mode may
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+	  be determined from EFI variables provided by the system firmware if
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+	  not indicated by the boot parameters.
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+
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+	  Enabling this option results in kernel lockdown being triggered if
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+	  EFI Secure Boot is set.
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+
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 choice
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 	prompt "Kernel default lockdown mode"
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 	default LOCK_DOWN_KERNEL_FORCE_NONE
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-- 
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2.21.0