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

Xu Kuohai
2024-07-20T09:29:38Z

On 7/19/2024 10:08 AM, Paul Moore wrote:
> On Jul 11, 2024 Xu Kuohai <xukuohai@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@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
>