[PATCH] x86/audit: fix -Wmissing-variable-declarations warning for ia32_xyz_class

[PATCH] x86/audit: fix -Wmissing-variable-declarations warning for ia32_xyz_class

[Justin Stitt]

When building x86 defconfig with Clang-18 I get the following warnings:
| arch/x86/ia32/audit.c:6:10: warning: no previous extern declaration for non-static variable 'ia32_dir_class' [-Wmissing-variable-declarations]
|     6 | unsigned ia32_dir_class[] = {
| arch/x86/ia32/audit.c:11:10: warning: no previous extern declaration for non-static variable 'ia32_chattr_class' [-Wmissing-variable-declarations]
|    11 | unsigned ia32_chattr_class[] = {
| arch/x86/ia32/audit.c:16:10: warning: no previous extern declaration for non-static variable 'ia32_write_class' [-Wmissing-variable-declarations]
|    16 | unsigned ia32_write_class[] = {
| arch/x86/ia32/audit.c:21:10: warning: no previous extern declaration for non-static variable 'ia32_read_class' [-Wmissing-variable-declarations]
|    21 | unsigned ia32_read_class[] = {
| arch/x86/ia32/audit.c:26:10: warning: no previous extern declaration for non-static variable 'ia32_signal_class' [-Wmissing-variable-declarations]
|    26 | unsigned ia32_signal_class[] = {

These warnings occur due to their respective extern declarations being
scoped inside of audit_classes_init as well as only being enabled with
`CONFIG_IA32_EMULATION=y`:
| static int __init audit_classes_init(void)
| {
| #ifdef CONFIG_IA32_EMULATION
| 	extern __u32 ia32_dir_class[];
| 	extern __u32 ia32_write_class[];
| 	extern __u32 ia32_read_class[];
| 	extern __u32 ia32_chattr_class[];
| 	audit_register_class(AUDIT_CLASS_WRITE_32, ia32_write_class);
| 	audit_register_class(AUDIT_CLASS_READ_32, ia32_read_class);
| 	audit_register_class(AUDIT_CLASS_DIR_WRITE_32, ia32_dir_class);
| 	audit_register_class(AUDIT_CLASS_CHATTR_32, ia32_chattr_class);
| #endif
| 	audit_register_class(AUDIT_CLASS_WRITE, write_class);
| 	audit_register_class(AUDIT_CLASS_READ, read_class);
| 	audit_register_class(AUDIT_CLASS_DIR_WRITE, dir_class);
| 	audit_register_class(AUDIT_CLASS_CHATTR, chattr_class);
| 	return 0;
| }

Lift the extern declarations to their own header and resolve scoping
issues (and thus fix the warnings).

Moreover, change __u32 to unsigned so that we match the definitions:
| unsigned ia32_dir_class[] = {
| #include <asm-generic/audit_dir_write.h>
| ~0U
| };
|
| unsigned ia32_chattr_class[] = {
| #include <asm-generic/audit_change_attr.h>
| ~0U
| };
| ...

This patch is similar to commit:
0e5e3d4461a22d73 ("x86/audit: Fix a -Wmissing-prototypes warning for ia32_classify_syscall()") [1]

Link: https://lore.kernel.org/all/20200516123816.2680-1-b.thiel@posteo.de/ [1]
Link: https://github.com/ClangBuiltLinux/linux/issues/1920
Signed-off-by: Justin Stitt <justinstitt@google.com>
---
Note: build-tested.
---
 arch/x86/include/asm/audit.h | 7 +++++++
 arch/x86/kernel/audit_64.c   | 5 -----
 2 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/arch/x86/include/asm/audit.h b/arch/x86/include/asm/audit.h
index 36aec57ea7a3..fa918f01333e 100644
--- a/arch/x86/include/asm/audit.h
+++ b/arch/x86/include/asm/audit.h
@@ -4,4 +4,11 @@
 
 int ia32_classify_syscall(unsigned int syscall);
 
+extern unsigned ia32_dir_class[];
+extern unsigned ia32_write_class[];
+extern unsigned ia32_read_class[];
+extern unsigned ia32_chattr_class[];
+extern unsigned ia32_signal_class[];
+
+
 #endif /* _ASM_X86_AUDIT_H */
diff --git a/arch/x86/kernel/audit_64.c b/arch/x86/kernel/audit_64.c
index 44c3601cfdc4..190c120f4285 100644
--- a/arch/x86/kernel/audit_64.c
+++ b/arch/x86/kernel/audit_64.c
@@ -63,11 +63,6 @@ int audit_classify_syscall(int abi, unsigned syscall)
 static int __init audit_classes_init(void)
 {
 #ifdef CONFIG_IA32_EMULATION
-	extern __u32 ia32_dir_class[];
-	extern __u32 ia32_write_class[];
-	extern __u32 ia32_read_class[];
-	extern __u32 ia32_chattr_class[];
-	extern __u32 ia32_signal_class[];
 	audit_register_class(AUDIT_CLASS_WRITE_32, ia32_write_class);
 	audit_register_class(AUDIT_CLASS_READ_32, ia32_read_class);
 	audit_register_class(AUDIT_CLASS_DIR_WRITE_32, ia32_dir_class);

---
base-commit: 706a741595047797872e669b3101429ab8d378ef
change-id: 20230829-missingvardecl-audit-493e36f2aa84

Best regards,
--
Justin Stitt <justinstitt@google.com>

[tip: x86/urgent] x86/audit: Fix -Wmissing-variable-declarations warning for ia32_xyz_class

[tip-bot2 for Justin Stitt]

The following commit has been merged into the x86/urgent branch of tip:

Commit-ID:     e8f13e061d75ed0eeaaf599532a6b197f195d5f3
Gitweb:        https://git.kernel.org/tip/e8f13e061d75ed0eeaaf599532a6b197f195d5f3
Author:        Justin Stitt <justinstitt@google.com>
AuthorDate:    Tue, 29 Aug 2023 22:33:16 
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Wed, 30 Aug 2023 10:11:16 +02:00

x86/audit: Fix -Wmissing-variable-declarations warning for ia32_xyz_class

When building x86 defconfig with Clang-18 I get the following warnings:

  | arch/x86/ia32/audit.c:6:10: warning: no previous extern declaration for non-static variable 'ia32_dir_class' [-Wmissing-variable-declarations]
  |     6 | unsigned ia32_dir_class[] = {
  | arch/x86/ia32/audit.c:11:10: warning: no previous extern declaration for non-static variable 'ia32_chattr_class' [-Wmissing-variable-declarations]
  |    11 | unsigned ia32_chattr_class[] = {
  | arch/x86/ia32/audit.c:16:10: warning: no previous extern declaration for non-static variable 'ia32_write_class' [-Wmissing-variable-declarations]
  |    16 | unsigned ia32_write_class[] = {
  | arch/x86/ia32/audit.c:21:10: warning: no previous extern declaration for non-static variable 'ia32_read_class' [-Wmissing-variable-declarations]
  |    21 | unsigned ia32_read_class[] = {
  | arch/x86/ia32/audit.c:26:10: warning: no previous extern declaration for non-static variable 'ia32_signal_class' [-Wmissing-variable-declarations]
  |    26 | unsigned ia32_signal_class[] = {

These warnings occur due to their respective extern declarations being
scoped inside of audit_classes_init as well as only being enabled with
`CONFIG_IA32_EMULATION=y`:

  | static int __init audit_classes_init(void)
  | {
  | #ifdef CONFIG_IA32_EMULATION
  |	extern __u32 ia32_dir_class[];
  |	extern __u32 ia32_write_class[];
  |	extern __u32 ia32_read_class[];
  |	extern __u32 ia32_chattr_class[];
  |	audit_register_class(AUDIT_CLASS_WRITE_32, ia32_write_class);
  |	audit_register_class(AUDIT_CLASS_READ_32, ia32_read_class);
  |	audit_register_class(AUDIT_CLASS_DIR_WRITE_32, ia32_dir_class);
  |	audit_register_class(AUDIT_CLASS_CHATTR_32, ia32_chattr_class);
  | #endif
  |	audit_register_class(AUDIT_CLASS_WRITE, write_class);
  |	audit_register_class(AUDIT_CLASS_READ, read_class);
  |	audit_register_class(AUDIT_CLASS_DIR_WRITE, dir_class);
  |	audit_register_class(AUDIT_CLASS_CHATTR, chattr_class);
  |	return 0;
  | }

Lift the extern declarations to their own header and resolve scoping
issues (and thus fix the warnings).

Moreover, change __u32 to unsigned so that we match the definitions:

  | unsigned ia32_dir_class[] = {
  | #include <asm-generic/audit_dir_write.h>
  | ~0U
  | };
  |
  | unsigned ia32_chattr_class[] = {
  | #include <asm-generic/audit_change_attr.h>
  | ~0U
  | };
  | ...

This patch is similar to commit:

  0e5e3d4461a22d73 ("x86/audit: Fix a -Wmissing-prototypes warning for ia32_classify_syscall()") [1]

Signed-off-by: Justin Stitt <justinstitt@google.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/all/20200516123816.2680-1-b.thiel@posteo.de/ [1]
Link: https://github.com/ClangBuiltLinux/linux/issues/1920
Link: https://lore.kernel.org/r/20230829-missingvardecl-audit-v1-1-34efeb7f3539@google.com
---
 arch/x86/include/asm/audit.h | 7 +++++++
 arch/x86/kernel/audit_64.c   | 5 -----
 2 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/arch/x86/include/asm/audit.h b/arch/x86/include/asm/audit.h
index 36aec57..fa918f0 100644
--- a/arch/x86/include/asm/audit.h
+++ b/arch/x86/include/asm/audit.h
@@ -4,4 +4,11 @@
 
 int ia32_classify_syscall(unsigned int syscall);
 
+extern unsigned ia32_dir_class[];
+extern unsigned ia32_write_class[];
+extern unsigned ia32_read_class[];
+extern unsigned ia32_chattr_class[];
+extern unsigned ia32_signal_class[];
+
+
 #endif /* _ASM_X86_AUDIT_H */
diff --git a/arch/x86/kernel/audit_64.c b/arch/x86/kernel/audit_64.c
index 44c3601..190c120 100644
--- a/arch/x86/kernel/audit_64.c
+++ b/arch/x86/kernel/audit_64.c
@@ -63,11 +63,6 @@ int audit_classify_syscall(int abi, unsigned syscall)
 static int __init audit_classes_init(void)
 {
 #ifdef CONFIG_IA32_EMULATION
-	extern __u32 ia32_dir_class[];
-	extern __u32 ia32_write_class[];
-	extern __u32 ia32_read_class[];
-	extern __u32 ia32_chattr_class[];
-	extern __u32 ia32_signal_class[];
 	audit_register_class(AUDIT_CLASS_WRITE_32, ia32_write_class);
 	audit_register_class(AUDIT_CLASS_READ_32, ia32_read_class);
 	audit_register_class(AUDIT_CLASS_DIR_WRITE_32, ia32_dir_class);

Re: [PATCH] x86/audit: fix -Wmissing-variable-declarations warning for ia32_xyz_class

[Kees Cook]

On Tue, Aug 29, 2023 at 10:33:16PM +0000, Justin Stitt wrote:
> When building x86 defconfig with Clang-18 I get the following warnings:
> | arch/x86/ia32/audit.c:6:10: warning: no previous extern declaration for non-static variable 'ia32_dir_class' [-Wmissing-variable-declarations]
> |     6 | unsigned ia32_dir_class[] = {
> | arch/x86/ia32/audit.c:11:10: warning: no previous extern declaration for non-static variable 'ia32_chattr_class' [-Wmissing-variable-declarations]
> |    11 | unsigned ia32_chattr_class[] = {
> | arch/x86/ia32/audit.c:16:10: warning: no previous extern declaration for non-static variable 'ia32_write_class' [-Wmissing-variable-declarations]
> |    16 | unsigned ia32_write_class[] = {
> | arch/x86/ia32/audit.c:21:10: warning: no previous extern declaration for non-static variable 'ia32_read_class' [-Wmissing-variable-declarations]
> |    21 | unsigned ia32_read_class[] = {
> | arch/x86/ia32/audit.c:26:10: warning: no previous extern declaration for non-static variable 'ia32_signal_class' [-Wmissing-variable-declarations]
> |    26 | unsigned ia32_signal_class[] = {
> 
> These warnings occur due to their respective extern declarations being
> scoped inside of audit_classes_init as well as only being enabled with
> `CONFIG_IA32_EMULATION=y`:
> | static int __init audit_classes_init(void)
> | {
> | #ifdef CONFIG_IA32_EMULATION
> | 	extern __u32 ia32_dir_class[];
> | 	extern __u32 ia32_write_class[];
> | 	extern __u32 ia32_read_class[];
> | 	extern __u32 ia32_chattr_class[];
> | 	audit_register_class(AUDIT_CLASS_WRITE_32, ia32_write_class);
> | 	audit_register_class(AUDIT_CLASS_READ_32, ia32_read_class);
> | 	audit_register_class(AUDIT_CLASS_DIR_WRITE_32, ia32_dir_class);
> | 	audit_register_class(AUDIT_CLASS_CHATTR_32, ia32_chattr_class);
> | #endif
> | 	audit_register_class(AUDIT_CLASS_WRITE, write_class);
> | 	audit_register_class(AUDIT_CLASS_READ, read_class);
> | 	audit_register_class(AUDIT_CLASS_DIR_WRITE, dir_class);
> | 	audit_register_class(AUDIT_CLASS_CHATTR, chattr_class);
> | 	return 0;
> | }
> 
> Lift the extern declarations to their own header and resolve scoping
> issues (and thus fix the warnings).
> 
> Moreover, change __u32 to unsigned so that we match the definitions:
> | unsigned ia32_dir_class[] = {
> | #include <asm-generic/audit_dir_write.h>
> | ~0U
> | };
> |
> | unsigned ia32_chattr_class[] = {
> | #include <asm-generic/audit_change_attr.h>
> | ~0U
> | };
> | ...

I would expect checkpatch to warn about bare "unsigned", which is frown
on these days. :) I think __u32 should be fine here...? (Why is it __u32
instead of u32, btw?)

But otherwise, yes, looks good.

-Kees

-- 
Kees Cook

Re: [PATCH] x86/audit: fix -Wmissing-variable-declarations warning for ia32_xyz_class

[Justin Stitt]

On Thu, Aug 31, 2023 at 2:11 PM Kees Cook <keescook@chromium.org> wrote:
>
> On Tue, Aug 29, 2023 at 10:33:16PM +0000, Justin Stitt wrote:
> > When building x86 defconfig with Clang-18 I get the following warnings:
> > | arch/x86/ia32/audit.c:6:10: warning: no previous extern declaration for non-static variable 'ia32_dir_class' [-Wmissing-variable-declarations]
> > |     6 | unsigned ia32_dir_class[] = {
> > | arch/x86/ia32/audit.c:11:10: warning: no previous extern declaration for non-static variable 'ia32_chattr_class' [-Wmissing-variable-declarations]
> > |    11 | unsigned ia32_chattr_class[] = {
> > | arch/x86/ia32/audit.c:16:10: warning: no previous extern declaration for non-static variable 'ia32_write_class' [-Wmissing-variable-declarations]
> > |    16 | unsigned ia32_write_class[] = {
> > | arch/x86/ia32/audit.c:21:10: warning: no previous extern declaration for non-static variable 'ia32_read_class' [-Wmissing-variable-declarations]
> > |    21 | unsigned ia32_read_class[] = {
> > | arch/x86/ia32/audit.c:26:10: warning: no previous extern declaration for non-static variable 'ia32_signal_class' [-Wmissing-variable-declarations]
> > |    26 | unsigned ia32_signal_class[] = {
> >
> > These warnings occur due to their respective extern declarations being
> > scoped inside of audit_classes_init as well as only being enabled with
> > `CONFIG_IA32_EMULATION=y`:
> > | static int __init audit_classes_init(void)
> > | {
> > | #ifdef CONFIG_IA32_EMULATION
> > |     extern __u32 ia32_dir_class[];
> > |     extern __u32 ia32_write_class[];
> > |     extern __u32 ia32_read_class[];
> > |     extern __u32 ia32_chattr_class[];
> > |     audit_register_class(AUDIT_CLASS_WRITE_32, ia32_write_class);
> > |     audit_register_class(AUDIT_CLASS_READ_32, ia32_read_class);
> > |     audit_register_class(AUDIT_CLASS_DIR_WRITE_32, ia32_dir_class);
> > |     audit_register_class(AUDIT_CLASS_CHATTR_32, ia32_chattr_class);
> > | #endif
> > |     audit_register_class(AUDIT_CLASS_WRITE, write_class);
> > |     audit_register_class(AUDIT_CLASS_READ, read_class);
> > |     audit_register_class(AUDIT_CLASS_DIR_WRITE, dir_class);
> > |     audit_register_class(AUDIT_CLASS_CHATTR, chattr_class);
> > |     return 0;
> > | }
> >
> > Lift the extern declarations to their own header and resolve scoping
> > issues (and thus fix the warnings).
> >
> > Moreover, change __u32 to unsigned so that we match the definitions:
> > | unsigned ia32_dir_class[] = {
> > | #include <asm-generic/audit_dir_write.h>
> > | ~0U
> > | };
> > |
> > | unsigned ia32_chattr_class[] = {
> > | #include <asm-generic/audit_change_attr.h>
> > | ~0U
> > | };
> > | ...
>
> I would expect checkpatch to warn about bare "unsigned", which is frown
> on these days. :) I think __u32 should be fine here...? (Why is it __u32
> instead of u32, btw?)

Yeah, checkpatch doesn't like it. I was just trying to mirror the
implementation in audit.c as closely as possible:
|     unsigned ia32_dir_class[] = {
|       #include <asm-generic/audit_dir_write.h>
|       ~0U
|     };


>
> But otherwise, yes, looks good.

Thanks for the feedback here. Should I send a v2 where I changed _all_
instances of `unsigned` in both audit.c and audit.h to be `u32`? Or
perhaps, `unsigned int`.

>
> -Kees
>
> --
> Kees Cook