Hii Ard

Am 19.12.23 um 12:38 schrieb Ard Biesheuvel:

Hi Thomas,

On Fri, 15 Dec 2023 at 13:26, Thomas Zimmermann [off-list ref] wrote:

quoted

The header file <asm/efi.h> contains the macro arch_ima_efi_boot_mode,
which expands to use struct boot_params from <asm/bootparams.h>. Many
drivers include <linux/efi.h>, but do not use boot parameters. Changes
to bootparam.h or its included headers can easily trigger large,
unnessary rebuilds of the kernel.

Moving x86's arch_ima_efi_boot_mode to <asm/ima-efi.h> and including
<asm/setup.h> separates that dependency from the rest of the EFI
interfaces. The only user is in ima_efi.c. As the file already declares
a default value for arch_ima_efi_boot_mode, move this define into
asm-generic for all other architectures.

With arch_ima_efi_boot_mode removed from efi.h, <asm/bootparam.h> can
later be removed from further x86 header files.

Apologies if I missed this in v1 but is the new asm-generic header
really necessary? Could we instead turn arch_ima_efi_boot_mode into a
function that is a static inline { return unset; } by default, but can
be emitted out of line in one of the x86/platform/efi.c source files,
where referring to boot_params is fine?

I cannot figure out how to do this without *something* in asm-generic or 
adding if-CONFIG_X86 guards in ima-efi.c.

But I noticed that linux/efi.h already contains 2 or 3 ifdef branches 
for x86. Would it be an option to move this code into asm/efi.h 
(including a header file in asm-generic for the non-x86 variants) and 
add the arch_ima_efi_boot_mode() helper there as well?  At least that 
wouldn't be a header for only a single define.

Best regards
Thomas

quoted

v2:
         * remove extra declaration of boot_params (Ard)

Please don't put the revision log here, but below the --- so that 'git
am' will ignore it.

quoted

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
  arch/x86/include/asm/efi.h       |  3 ---
  arch/x86/include/asm/ima-efi.h   | 11 +++++++++++
  include/asm-generic/Kbuild       |  1 +
  include/asm-generic/ima-efi.h    | 16 ++++++++++++++++
  security/integrity/ima/ima_efi.c |  5 +----
  5 files changed, 29 insertions(+), 7 deletions(-)
  create mode 100644 arch/x86/include/asm/ima-efi.h
  create mode 100644 include/asm-generic/ima-efi.h

diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
index c4555b269a1b..99f31176c892 100644
--- a/arch/x86/include/asm/efi.h
+++ b/arch/x86/include/asm/efi.h

@@ -418,9 +418,6 @@ extern int __init efi_memmap_split_count(efi_memory_desc_t *md,
  extern void __init efi_memmap_insert(struct efi_memory_map *old_memmap,
                                      void *buf, struct efi_mem_range *mem);

-#define arch_ima_efi_boot_mode \
-       ({ extern struct boot_params boot_params; boot_params.secure_boot; })
-
  #ifdef CONFIG_EFI_RUNTIME_MAP
  int efi_get_runtime_map_size(void);
  int efi_get_runtime_map_desc_size(void);

diff --git a/arch/x86/include/asm/ima-efi.h b/arch/x86/include/asm/ima-efi.h
new file mode 100644
index 000000000000..b4d904e66b39
--- /dev/null
+++ b/arch/x86/include/asm/ima-efi.h

@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_X86_IMA_EFI_H
+#define _ASM_X86_IMA_EFI_H
+
+#include <asm/setup.h>
+
+#define arch_ima_efi_boot_mode boot_params.secure_boot
+
+#include <asm-generic/ima-efi.h>
+
+#endif /* _ASM_X86_IMA_EFI_H */

diff --git a/include/asm-generic/Kbuild b/include/asm-generic/Kbuild
index def242528b1d..4fd16e71e8cd 100644
--- a/include/asm-generic/Kbuild
+++ b/include/asm-generic/Kbuild

@@ -26,6 +26,7 @@ mandatory-y += ftrace.h
  mandatory-y += futex.h
  mandatory-y += hardirq.h
  mandatory-y += hw_irq.h
+mandatory-y += ima-efi.h
  mandatory-y += io.h
  mandatory-y += irq.h
  mandatory-y += irq_regs.h

diff --git a/include/asm-generic/ima-efi.h b/include/asm-generic/ima-efi.h
new file mode 100644
index 000000000000..f87f5edef440
--- /dev/null
+++ b/include/asm-generic/ima-efi.h

@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+
+#ifndef __ASM_GENERIC_IMA_EFI_H_
+#define __ASM_GENERIC_IMA_EFI_H_
+
+#include <linux/efi.h>
+
+/*
+ * Only include this header file from your architecture's <asm/ima-efi.h>.
+ */
+
+#ifndef arch_ima_efi_boot_mode
+#define arch_ima_efi_boot_mode efi_secureboot_mode_unset
+#endif
+
+#endif /* __ASM_GENERIC_FB_H_ */

diff --git a/security/integrity/ima/ima_efi.c b/security/integrity/ima/ima_efi.c
index 138029bfcce1..56bbee271cec 100644
--- a/security/integrity/ima/ima_efi.c
+++ b/security/integrity/ima/ima_efi.c

@@ -6,10 +6,7 @@
  #include <linux/module.h>
  #include <linux/ima.h>
  #include <asm/efi.h>
-
-#ifndef arch_ima_efi_boot_mode
-#define arch_ima_efi_boot_mode efi_secureboot_mode_unset
-#endif
+#include <asm/ima-efi.h>

  static enum efi_secureboot_mode get_sb_mode(void)
  {
--

2.43.0

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)