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

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Date:   Mon, 02 May 2022 08:14:12 -0400
From:   Mimi Zohar <zohar@...ux.ibm.com>
To:     Stefan Berger <stefanb@...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 Fri, 2022-04-29 at 12:44 -0400, Stefan Berger wrote:
> 
> 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'

And initially for d-ng before it was upstreamed.

> 
> > +   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>

Thank you, Stefan, for this and the other tags!

Mimi