linux-kernel - Re: [PATCH v8 1/7] ima: fix 'd-ng' comments and documentation

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Date:   Fri, 29 Apr 2022 12:44:41 -0400
From:   Stefan Berger <stefanb@...ux.ibm.com>
To:     Mimi Zohar <zohar@...ux.ibm.com>, linux-integrity@...r.kernel.org
Cc:     Eric Biggers <ebiggers@...nel.org>, linux-fscrypt@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v8 1/7] ima: fix 'd-ng' comments and documentation



On 4/29/22 07:25, Mimi Zohar wrote:
> Initially the 'd-ng' template field did not prefix the digest with either
> "md5" or "sha1" hash algorithms.  Prior to being upstreamed this changed,
> but the comments and documentation were not updated.  Fix the comments
> and documentation.
> 
> Fixes: 4d7aeee73f53 ("ima: define new template ima-ng and template fields d-ng and n-ng")
> Reported-by: Eric Biggers <ebiggers@...nel.org>
> Signed-off-by: Mimi Zohar <zohar@...ux.ibm.com>
> ---
>   Documentation/security/IMA-templates.rst  | 3 +--
>   security/integrity/ima/ima_template_lib.c | 8 +++++---
>   2 files changed, 6 insertions(+), 5 deletions(-)
> 
> diff --git a/Documentation/security/IMA-templates.rst b/Documentation/security/IMA-templates.rst
> index 1a91d92950a7..cab97f49971d 100644
> --- a/Documentation/security/IMA-templates.rst
> +++ b/Documentation/security/IMA-templates.rst
> @@ -66,8 +66,7 @@ descriptors by adding their identifier to the format string
>      calculated with the SHA1 or MD5 hash algorithm;
>    - 'n': the name of the event (i.e. the file name), with size up to 255 bytes;
>    - 'd-ng': the digest of the event, calculated with an arbitrary hash
> -   algorithm (field format: [<hash algo>:]digest, where the digest
> -   prefix is shown only if the hash algorithm is not SHA1 or MD5);

That seemed to be true for 'd'

> +   algorithm (field format: <hash algo>:digest);
>    - 'd-modsig': the digest of the event without the appended modsig;
>    - 'n-ng': the name of the event, without size limitations;
>    - 'sig': the file signature, or the EVM portable signature if the file
> diff --git a/security/integrity/ima/ima_template_lib.c b/security/integrity/ima/ima_template_lib.c
> index 7155d17a3b75..e9d65f6fe2ae 100644
> --- a/security/integrity/ima/ima_template_lib.c
> +++ b/security/integrity/ima/ima_template_lib.c
> @@ -271,9 +271,11 @@ static int ima_eventdigest_init_common(const u8 *digest, u32 digestsize,
>   	/*
>   	 * digest formats:
>   	 *  - DATA_FMT_DIGEST: digest
> -	 *  - DATA_FMT_DIGEST_WITH_ALGO: [<hash algo>] + ':' + '\0' + digest,
> -	 *    where <hash algo> is provided if the hash algorithm is not
> -	 *    SHA1 or MD5
> +	 *  - DATA_FMT_DIGEST_WITH_ALGO: <hash algo> + ':' + '\0' + digest, > +	 *
> +	 *    where 'DATA_FMT_DIGEST' is the original digest format ('d')
> +	 *      with a hash size limitation of 20 bytes,
> +	 *    where <hash algo> is the hash_algo_name[] string.
>   	 */
>   	u8 buffer[CRYPTO_MAX_ALG_NAME + 2 + IMA_MAX_DIGEST_SIZE] = { 0 };
>   	enum data_formats fmt = DATA_FMT_DIGEST;

Reviewed-by: Stefan Berger <stefanb@...ux.ibm.com>