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

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Message-ID: <20200623101042.GB1523@xiangao.remote.csb>
Date:   Tue, 23 Jun 2020 18:10:42 +0800
From:   Gao Xiang <hsiangkao@...hat.com>
To:     Alexander Viro <viro@...iv.linux.org.uk>
Cc:     linux-fsdevel@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
        Stephen Smalley <sds@...ho.nsa.gov>,
        Chengguang Xu <cgxu519@...ernel.net>,
        Chao Yu <yuchao0@...wei.com>
Subject: Re: [PATCH] xattr: fix EOPNOTSUPP if fs and security xattrs disabled

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@...iv.linux.org.uk>
> Cc: Stephen Smalley <sds@...ho.nsa.gov>
> Cc: Chengguang Xu <cgxu519@...ernel.net>
> Cc: Chao Yu <yuchao0@...wei.com>
> Signed-off-by: Gao Xiang <hsiangkao@...hat.com>
> ---
> 
> 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@mykernel.net
> 
> 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
>