[PATCH v4 5/20] lsm: Refactor return value of LSM hook inode_copy_up_xattr

[Xu Kuohai]

On 7/19/2024 10:08 AM, Paul Moore wrote:
> On Jul 11, 2024 Xu Kuohai <xukuohai at huaweicloud.com> wrote:
>>
>> To be consistent with most LSM hooks, convert the return value of
>> hook inode_copy_up_xattr to 0 or a negative error code.
>>
>> Before:
>> - Hook inode_copy_up_xattr returns 0 when accepting xattr, 1 when
>>    discarding xattr, -EOPNOTSUPP if it does not know xattr, or any
>>    other negative error code otherwise.
>>
>> After:
>> - Hook inode_copy_up_xattr returns 0 when accepting xattr, *-ECANCELED*
>>    when discarding xattr, -EOPNOTSUPP if it does not know xattr, or
>>    any other negative error code otherwise.
>>
>> Signed-off-by: Xu Kuohai <xukuohai at huawei.com>
>> ---
>>   fs/overlayfs/copy_up.c            |  6 +++---
>>   security/integrity/evm/evm_main.c |  2 +-
>>   security/security.c               | 12 ++++++------
>>   security/selinux/hooks.c          |  4 ++--
>>   security/smack/smack_lsm.c        |  6 +++---
>>   5 files changed, 15 insertions(+), 15 deletions(-)
> 
> ...
> 
>> diff --git a/security/security.c b/security/security.c
>> index 26eea8f4cd74..12215ca286af 100644
>> --- a/security/security.c
>> +++ b/security/security.c
>> @@ -2675,18 +2675,18 @@ EXPORT_SYMBOL(security_inode_copy_up);
>>    * lower layer to the union/overlay layer.   The caller is responsible for
>>    * reading and writing the xattrs, this hook is merely a filter.
>>    *
>> - * Return: Returns 0 to accept the xattr, 1 to discard the xattr, -EOPNOTSUPP
>> - *         if the security module does not know about attribute, or a negative
>> - *         error code to abort the copy up.
>> + * Return: Returns 0 to accept the xattr, -ECANCELED to discard the xattr,
>> + *         -EOPNOTSUPP if the security module does not know about attribute,
>> + *         or a negative error code to abort the copy up.
>>    */
>>   int security_inode_copy_up_xattr(struct dentry *src, const char *name)
>>   {
>>   	int rc;
>>   
>>   	/*
>> -	 * The implementation can return 0 (accept the xattr), 1 (discard the
>> -	 * xattr), -EOPNOTSUPP if it does not know anything about the xattr or
>> -	 * any other error code in case of an error.
>> +	 * The implementation can return 0 (accept the xattr), -ECANCELED
>> +	 * (discard the xattr), -EOPNOTSUPP if it does not know anything
>> +	 *  about the xattr or any other error code in case of an error.
>>   	 */
> 
> Updating the comment here is good, but considering that we also discuss
> the return value in the function header comment, I think it might be
> better to just remove this comment entirely and leave the function header
> comment as the single source.  Duplicated comments/docs tend to fall out
> of sync and create confusion.
>

OK, will do

>>   	rc = call_int_hook(inode_copy_up_xattr, src, name);
>>   	if (rc != LSM_RET_DEFAULT(inode_copy_up_xattr))
> 
> 
> --
> paul-moore.com
>