linux-kernel - Re: [PATCH] ima: silence measurement list hexdump during kexec

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Date:   Wed, 22 Dec 2021 17:13:56 -0500
From:   Mimi Zohar <zohar@...ux.ibm.com>
To:     Bruno Meneguele <bmeneg@...hat.com>
Cc:     linux-integrity@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ima: silence measurement list hexdump during kexec

Hi Bruno,

On Wed, 2021-12-22 at 16:16 -0300, Bruno Meneguele wrote:
> The measurement list is dumped during a soft reset (kexec) through the call
> to "print_hex_dump(KERN_DEBUG, ...)", which ignores the DEBUG build flag.
> Instead, use "print_hex_dump_debug(...)", honoring the build flag.
> 
> Signed-off-by: Bruno Meneguele <bmeneg@...hat.com>

The patch description needs to at least explain why using
print_hex_dump() isn't sufficent.   Look at how print_hex_dump() is
defined.  Based on whether CONFIG_DYNAMIC_DEBUG is enabled, different
functions are used.

Mimi

> ---
>  security/integrity/ima/ima_kexec.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c
> index f799cc278a9a..13753136f03f 100644
> --- a/security/integrity/ima/ima_kexec.c
> +++ b/security/integrity/ima/ima_kexec.c
> @@ -61,9 +61,9 @@ static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer,
>  	}
>  	memcpy(file.buf, &khdr, sizeof(khdr));
>  
> -	print_hex_dump(KERN_DEBUG, "ima dump: ", DUMP_PREFIX_NONE,
> -			16, 1, file.buf,
> -			file.count < 100 ? file.count : 100, true);
> +	print_hex_dump_debug("ima dump: ", DUMP_PREFIX_NONE, 16, 1,
> +			     file.buf, file.count < 100 ? file.count : 100,
> +			     true);
>  
>  	*buffer_size = file.count;
>  	*buffer = file.buf;