linux-kernel - Re: [Linux-ima-devel] [PATCH v1 1/3] ima: provide flag to identify new empty files

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Date:	Wed, 16 Jul 2014 10:56:06 +0300
From:	Dmitry Kasatkin <d.kasatkin@...sung.com>
To:	Mimi Zohar <zohar@...ux.vnet.ibm.com>
Cc:	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	linux-security-module@...r.kernel.org, viro@...iv.linux.org.uk,
	linux-ima-devel@...ts.sourceforge.net
Subject: Re: [Linux-ima-devel] [PATCH v1 1/3] ima: provide flag to identify new
 empty files

On 16/07/14 01:12, Mimi Zohar wrote:
> On Tue, 2014-07-15 at 10:00 -0400, Mimi Zohar wrote: 
>> On Fri, 2014-07-11 at 14:46 +0300, Dmitry Kasatkin wrote: 
>>> Newly created empty files do not get initial security.ima
>>> value because iversion does not change. It can be checked from
>>> the shell as:
>>>
>>>   $ (exec >foo)
>>>   $ getfattr -h -e hex -d -m security foo
> This is a change in behavior.  Please include the commit number that
> introduced this change in the patch description.

This commit might caused this.
dff6efc326a4d5f305797d4a6bba14f374fdd633 fs: fix iversion handling

- Dmitry

> Mimi
>
>>> This patch defines IMA_NEW_FILE flag which is set when IMA detects that new
>>> file is created. It is checked upon ima_file_free hook to set initial
>>> security.ima value.
>> Other than rebasing on top of #next, this patch set looks good.
>>
>> thanks,
>>
>> Mimi
>>
>>> Signed-off-by: Dmitry Kasatkin <d.kasatkin@...sung.com>
>>> ---
>>>  security/integrity/ima/ima_appraise.c |  7 +++++--
>>>  security/integrity/ima/ima_main.c     | 12 +++++++-----
>>>  security/integrity/integrity.h        |  1 +
>>>  3 files changed, 13 insertions(+), 7 deletions(-)
>>>
>>> diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
>>> index 9dd18b5..3a4beb3 100644
>>> --- a/security/integrity/ima/ima_appraise.c
>>> +++ b/security/integrity/ima/ima_appraise.c
>>> @@ -194,8 +194,11 @@ int ima_appraise_measurement(int func, struct integrity_iint_cache *iint,
>>>  			goto out;
>>>
>>>  		cause = "missing-hash";
>>> -		status =
>>> -		    (inode->i_size == 0) ? INTEGRITY_PASS : INTEGRITY_NOLABEL;
>>> +		status = INTEGRITY_NOLABEL;
>>> +		if (inode->i_size == 0) {
>>> +			iint->flags |= IMA_NEW_FILE;
>>> +			status = INTEGRITY_PASS;
>>> +		}
>>>  		goto out;
>>>  	}
>>>
>>> diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
>>> index e51e0d5..5a870e7 100644
>>> --- a/security/integrity/ima/ima_main.c
>>> +++ b/security/integrity/ima/ima_main.c
>>> @@ -124,11 +124,13 @@ static void ima_check_last_writer(struct integrity_iint_cache *iint,
>>>  		return;
>>>
>>>  	mutex_lock(&iint->mutex);
>>> -	if (atomic_read(&inode->i_writecount) == 1 &&
>>> -	    iint->version != inode->i_version) {
>>> -		iint->flags &= ~IMA_DONE_MASK;
>>> -		if (iint->flags & IMA_APPRAISE)
>>> -			ima_update_xattr(iint, file);
>>> +	if (atomic_read(&inode->i_writecount) == 1) {
>>> +		if ((iint->version != inode->i_version) ||
>>> +		    (iint->flags & IMA_NEW_FILE)) {
>>> +			iint->flags &= ~(IMA_DONE_MASK | IMA_NEW_FILE);
>>> +			if (iint->flags & IMA_APPRAISE)
>>> +				ima_update_xattr(iint, file);
>>> +		}
>>>  	}
>>>  	mutex_unlock(&iint->mutex);
>>>  }
>>> diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h
>>> index 92c1083..7656d47 100644
>>> --- a/security/integrity/integrity.h
>>> +++ b/security/integrity/integrity.h
>>> @@ -30,6 +30,7 @@
>>>  #define IMA_ACTION_FLAGS	0xff000000
>>>  #define IMA_DIGSIG_REQUIRED	0x01000000
>>>  #define IMA_PERMIT_DIRECTIO	0x02000000
>>> +#define IMA_NEW_FILE		0x04000000
>>>
>>>  #define IMA_DO_MASK		(IMA_MEASURE | IMA_APPRAISE | IMA_AUDIT | \
>>>  				 IMA_APPRAISE_SUBMASK)
>>
>>
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>> _______________________________________________
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>> Linux-ima-devel@...ts.sourceforge.net
>> https://lists.sourceforge.net/lists/listinfo/linux-ima-devel
>>
>
>

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