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Date:   Wed, 7 Oct 2020 00:02:17 -0700
From:   Kees Cook <keescook@chromium.org>
To:     Nathan Chancellor <natechancellor@gmail.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     James Morris <jmorris@namei.org>, KP Singh <kpsingh@google.com>,
        Nick Desaulniers <ndesaulniers@google.com>,
        linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com
Subject: Re: [PATCH] LSM: Fix type of id parameter in kernel_post_load_data
 prototype
Message-ID: <202010062359.01DD51D3@keescook>
References: <20201006201115.716550-1-natechancellor@gmail.com>
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In-Reply-To: <20201006201115.716550-1-natechancellor@gmail.com>
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On Tue, Oct 06, 2020 at 01:11:15PM -0700, Nathan Chancellor wrote:
> Clang warns:
> 
> security/security.c:1716:59: warning: implicit conversion from
> enumeration type 'enum kernel_load_data_id' to different enumeration
> type 'enum kernel_read_file_id' [-Wenum-conversion]
>         ret = call_int_hook(kernel_post_load_data, 0, buf, size, id,
>               ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
> security/security.c:715:22: note: expanded from macro 'call_int_hook'
>                         RC = P->hook.FUNC(__VA_ARGS__);         \
>                              ~            ^~~~~~~~~~~
> 1 warning generated.
> 
> There is a mismatch between the id parameter type in
> security_kernel_post_load_data and the function pointer prototype that
> is created by the LSM_HOOK macro in the security_list_options union. Fix
> the type in the LSM_HOOK macro as 'enum kernel_load_data_id' is what is
> expected.
> 
> Fixes: b64fcae74b6d ("LSM: Introduce kernel_post_load_data() hook")
> Link: https://github.com/ClangBuiltLinux/linux/issues/1172
> Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>

Ah yes; thank you! Greg, can you add this to your tree?

Acked-by: Kees Cook <keescook@chromium.org>

-Kees

> ---
>  include/linux/lsm_hook_defs.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
> index d67cb3502310..32a940117e7a 100644
> --- a/include/linux/lsm_hook_defs.h
> +++ b/include/linux/lsm_hook_defs.h
> @@ -186,7 +186,7 @@ LSM_HOOK(int, 0, kernel_create_files_as, struct cred *new, struct inode *inode)
>  LSM_HOOK(int, 0, kernel_module_request, char *kmod_name)
>  LSM_HOOK(int, 0, kernel_load_data, enum kernel_load_data_id id, bool contents)
>  LSM_HOOK(int, 0, kernel_post_load_data, char *buf, loff_t size,
> -	 enum kernel_read_file_id id, char *description)
> +	 enum kernel_load_data_id id, char *description)
>  LSM_HOOK(int, 0, kernel_read_file, struct file *file,
>  	 enum kernel_read_file_id id, bool contents)
>  LSM_HOOK(int, 0, kernel_post_read_file, struct file *file, char *buf,
> 
> base-commit: dba8648dcab90564b8a11c952c06a9e1153506fb
> -- 
> 2.29.0.rc0
> 

-- 
Kees Cook