linux-kernel - Re: [PATCH] ima: Defer query for iversion until it is needed

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Date:   Thu, 30 Jun 2022 09:24:18 -0400
From:   Mimi Zohar <zohar@...ux.ibm.com>
To:     Stefan Berger <stefanb@...ux.ibm.com>,
        linux-integrity@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ima: Defer query for iversion until it is needed

Hi Stefan,

On Wed, 2022-06-29 at 22:03 -0400, Stefan Berger wrote:
> Defer the query for the iversion until it is needed.
> 
> Signed-off-by: Stefan Berger <stefanb@...ux.ibm.com>
> ---
>  security/integrity/ima/ima_api.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
> index c1e76282b5ee..4410d45eb281 100644
> --- a/security/integrity/ima/ima_api.c
> +++ b/security/integrity/ima/ima_api.c
> @@ -248,7 +248,6 @@ int ima_collect_measurement(struct integrity_iint_cache *iint,
>  	int result = 0;
>  	int length;
>  	void *tmpbuf;
> -	u64 i_version;
>  
>  	/*
>  	 * Always collect the modsig, because IMA might have already collected
> @@ -267,7 +266,6 @@ int ima_collect_measurement(struct integrity_iint_cache *iint,
>  	 * to an initial measurement/appraisal/audit, but was modified to
>  	 * assume the file changed.
>  	 */
> -	i_version = inode_query_iversion(inode);
>  	hash.hdr.algo = algo;
>  	hash.hdr.length = hash_digest_size[algo];
>  
> @@ -304,7 +302,7 @@ int ima_collect_measurement(struct integrity_iint_cache *iint,
>  
>  	iint->ima_hash = tmpbuf;
>  	memcpy(iint->ima_hash, &hash, length);
> -	iint->version = i_version;
> +	iint->version = inode_query_iversion(inode);
>  
>  	/* Possibly temporary failure due to type of read (eg. O_DIRECT) */
>  	if (!result)

Using the i_version value before calculating the file hash was done
intentionally in case the file changed.

thanks,

Mimi