Re: [PATCH] xattr: fix EOPNOTSUPP if fs and security xattrs disabled

[Gao Xiang]

Friendly ping...

On Wed, May 27, 2020 at 12:40:37PM +0800, Gao Xiang wrote:
> commit f549d6c18c0e ("[PATCH] Generic VFS fallback for security xattrs")
> introduces a behavior change of listxattr path therefore listxattr(2)
> won't report EOPNOTSUPP correctly if fs and security xattrs disabled.
> However it was clearly recorded in manpage all the time.
> 
> Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
> Cc: Stephen Smalley <sds@xxxxxxxxxxxxx>
> Cc: Chengguang Xu <cgxu519@xxxxxxxxxxxx>
> Cc: Chao Yu <yuchao0@xxxxxxxxxx>
> Signed-off-by: Gao Xiang <hsiangkao@xxxxxxxxxx>
> ---
> 
> Noticed when reviewing Chengguang's patch for erofs [1] (together
> with ext2, f2fs). I'm not sure if it's the best approach but it
> seems that security_inode_listsecurity() has other users and it
> mainly focus on reporting these security xattrs...
> 
> [1] https://lore.kernel.org/r/20200526090343.22794-1-cgxu519@xxxxxxxxxxxx
> 
> Thanks,
> Gao Xiang
> 
>  fs/xattr.c | 16 +++++++++-------
>  1 file changed, 9 insertions(+), 7 deletions(-)
> 
> diff --git a/fs/xattr.c b/fs/xattr.c
> index 91608d9bfc6a..f339a67db521 100644
> --- a/fs/xattr.c
> +++ b/fs/xattr.c
> @@ -352,13 +352,15 @@ vfs_listxattr(struct dentry *dentry, char *list, size_t size)
>  	error = security_inode_listxattr(dentry);
>  	if (error)
>  		return error;
> -	if (inode->i_op->listxattr && (inode->i_opflags & IOP_XATTR)) {
> -		error = inode->i_op->listxattr(dentry, list, size);
> -	} else {
> -		error = security_inode_listsecurity(inode, list, size);
> -		if (size && error > size)
> -			error = -ERANGE;
> -	}
> +
> +	if (inode->i_op->listxattr && (inode->i_opflags & IOP_XATTR))
> +		return inode->i_op->listxattr(dentry, list, size);
> +
> +	if (!IS_ENABLED(CONFIG_SECURITY))
> +		return -EOPNOTSUPP;
> +	error = security_inode_listsecurity(inode, list, size);
> +	if (size && error > size)
> +		error = -ERANGE;
>  	return error;
>  }
>  EXPORT_SYMBOL_GPL(vfs_listxattr);
> -- 
> 2.24.0
>