[RFC][PATCH v2 2/9] ima: preserve flags in ima_inode_post_setattr() if file must be appraised

[Mimi Zohar]

On Thu, 2017-11-30 at 11:56 +0100, Roberto Sassu wrote:
> Before commit d79d72e02485 ("ima: per hook cache integrity appraisal
> status"), ima_inode_post_setattr() clears the iint flags only if the file
> does not match policy rules after attributes changed. After the commit
> above, it clears the flags in any case. This patch restores the original
> behavior.
> 
> Signed-off-by: Roberto Sassu <roberto.sassu at huawei.com>

Prior to this commit, the file was either in/out of policy for all
hooks.  This commit introduced the concept of different hooks
requiring different types of integrity appraisal (eg. hash,
signature).  An attribute change (eg. fowner) could require a
different type of integrity appraisal.  With this patch, knowing just
that a file is in/out of policy isn't fine grained enough.

Mimi

> ---
>  security/integrity/ima/ima_appraise.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
> index 1b56ee949315..a54ad18affb1 100644
> --- a/security/integrity/ima/ima_appraise.c
> +++ b/security/integrity/ima/ima_appraise.c
> @@ -360,11 +360,13 @@ void ima_inode_post_setattr(struct dentry *dentry)
>  	must_appraise = ima_must_appraise(inode, MAY_ACCESS, POST_SETATTR);
>  	iint = integrity_iint_find(inode);
>  	if (iint) {
> -		iint->flags &= ~(IMA_APPRAISE | IMA_APPRAISED |
> -				 IMA_APPRAISE_SUBMASK | IMA_APPRAISED_SUBMASK |
> -				 IMA_ACTION_RULE_FLAGS);
>  		if (must_appraise)
>  			iint->flags |= IMA_APPRAISE;
> +		else
> +			iint->flags &= ~(IMA_APPRAISE | IMA_APPRAISED |
> +					 IMA_APPRAISE_SUBMASK |
> +					 IMA_APPRAISED_SUBMASK |
> +					 IMA_ACTION_RULE_FLAGS);
>  	}
>  	if (!must_appraise)
>  		__vfs_removexattr(dentry, XATTR_NAME_IMA);

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