linux-kernel - Re: [PATCH 1/8] ima: fix erronous removal of security.ima xattr

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Date:	Mon, 03 Mar 2014 08:43:42 -0500
From:	Mimi Zohar <zohar@...ux.vnet.ibm.com>
To:	Dmitry Kasatkin <d.kasatkin@...sung.com>
Cc:	linux-security-module@...r.kernel.org, jmorris@...ei.org,
	linux-kernel@...r.kernel.org, casey.schaufler@...el.com,
	dmitry.kasatkin@...il.com
Subject: Re: [PATCH 1/8] ima: fix erronous removal of security.ima xattr

On Fri, 2014-02-28 at 16:59 +0200, Dmitry Kasatkin wrote: 
> ima_inode_post_setattr() calls ima_must_appraise() to check if
> file needs to be appraised. If it is not then it removes security.ima
> xattr. With original policy matching code it might happen that even
> file needs to be appraised with FILE_CHECK hook, it might not be
> for POST_SETATTR hook. 'security.ima' might be erronously removed.
> 
> This patch treats POST_SETATTR as special wildcard function and will
> cause ima_must_appraise() to be true if any of the hooks rules matches.
> security.ima will not be removed if any of the hooks would require
> appraisal.
> 
> Signed-off-by: Dmitry Kasatkin <d.kasatkin@...sung.com>

Thanks!

Mimi 
> ---
>  security/integrity/ima/ima_policy.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
> index d7c97a4..947cdbe 100644
> --- a/security/integrity/ima/ima_policy.c
> +++ b/security/integrity/ima/ima_policy.c
> @@ -167,9 +167,11 @@ static bool ima_match_rules(struct ima_rule_entry *rule,
>  	const struct cred *cred = current_cred();
>  	int i;
> 
> -	if ((rule->flags & IMA_FUNC) && rule->func != func)
> +	if ((rule->flags & IMA_FUNC) &&
> +		    (rule->func != func && func != POST_SETATTR))
>  		return false;
> -	if ((rule->flags & IMA_MASK) && rule->mask != mask)
> +	if ((rule->flags & IMA_MASK) &&
> +		    (rule->mask != mask && func != POST_SETATTR))
>  		return false;
>  	if ((rule->flags & IMA_FSMAGIC)
>  	    && rule->fsmagic != inode->i_sb->s_magic)


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