linux-kernel - Re: [PATCH -V1 09/22] vfs: Make acl_permission

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Message-ID: <87fvktbj9w.fsf@linux.vnet.ibm.com>
Date:	Thu, 01 May 2014 21:09:23 +0530
From:	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
To:	Dave Chinner <david@...morbit.com>
Cc:	agruen@...nel.org, bfields@...ldses.org, akpm@...ux-foundation.org,
	viro@...iv.linux.org.uk, dhowells@...hat.com,
	linux-fsdevel@...r.kernel.org, linux-nfs@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH -V1 09/22] vfs: Make acl_permission_check() work for richacls

Dave Chinner <david@...morbit.com> writes:

> On Sun, Apr 27, 2014 at 09:44:40PM +0530, Aneesh Kumar K.V wrote:
>> From: Andreas Gruenbacher <agruen@...nel.org>
>> 
>> Signed-off-by: Andreas Gruenbacher <agruen@...nel.org>
>> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@...ux.vnet.ibm.com>
>> ---
>>  fs/namei.c | 13 +++++++++++++
>>  1 file changed, 13 insertions(+)
>> 
>> diff --git a/fs/namei.c b/fs/namei.c
>> index 26b9a8212837..06474553c08d 100644
>> --- a/fs/namei.c
>> +++ b/fs/namei.c
>> @@ -284,6 +284,19 @@ static int acl_permission_check(struct inode *inode, int mask)
>>  {
>>  	unsigned int mode = inode->i_mode;
>>  
>> +	if (IS_RICHACL(inode)) {
>> +		int error = check_acl(inode, mask);
>> +		if (error != -EAGAIN)
>> +			return error;
>> +		if (mask & (MAY_DELETE_SELF | MAY_TAKE_OWNERSHIP |
>> +			    MAY_CHMOD | MAY_SET_TIMES)) {
>> +			/*
>> +			 * The file permission bit cannot grant these
>> +			 * permissions.
>> +			 */
>> +			return -EACCES;
>> +		}
>> +	}
>>  	if (likely(uid_eq(current_fsuid(), inode->i_uid)))
>>  		mode >>= 6;
>>  	else {
>
> why does this take priority over a simple uid match? Some comments
> explaining this for people unfamiliar with richacls would be nice.
> Not to mention the commit message should also explain the change...
>

Richacl can have further limitation on file owner. Will add more
comments around the function.

-aneesh

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