linux-kernel - Re: [PATCH -V4 08/11] vfs: Add new file and directory create permission flags

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Message-ID: <20110102232101.GB11955@thunk.org>
Date:	Sun, 2 Jan 2011 18:21:01 -0500
From:	Ted Ts'o <tytso@....edu>
To:	Andreas Gruenbacher <agruen@...e.de>
Cc:	Jeff Layton <jlayton@...hat.com>,
	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
	sfrench@...ibm.com, ffilz@...ibm.com, adilger@....com,
	sandeen@...hat.com, bfields@...i.umich.edu,
	linux-fsdevel@...r.kernel.org, nfsv4@...ux-nfs.org,
	linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH -V4 08/11] vfs: Add new file and directory create
 permission flags

I was going through some old patches in the ext4 patchwork list, and
came across this.  It looks like this patch has never been applied to
mainline.  If it's a "clear improvement", any reason not to submit it?

Regards,

	      	     	    		      - Ted

On Mon, Sep 27, 2010 at 03:14:00PM +0200, Andreas Gruenbacher wrote:
> 
> Ah, you mean this:
> 
> --- a/fs/namei.c
> +++ b/fs/namei.c
> @@ -2450,7 +2450,9 @@ int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_de
>  	if (!inode)
>  		return -ENOENT;
>  
> -	error = may_create(dir, new_dentry, S_ISDIR(inode->i_mode));
> +	if (S_ISDIR(inode->i_mode))
> +		return -EPERM;
> +	error = may_create(dir, new_dentry, 0);
>  	if (error)
>  		return error;
>  
> @@ -2464,8 +2466,6 @@ int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_de
>  		return -EPERM;
>  	if (!dir->i_op->link)
>  		return -EPERM;
> -	if (S_ISDIR(inode->i_mode))
> -		return -EPERM;
>  
>  	error = security_inode_link(old_dentry, dir, new_dentry);
>  	if (error)
> 
> This is a clear improvement; I don't think it matters that user-space will
> get -EPERM instead of -EXDEV when trying to hard-link a directory across
> devices.
> 
> Thanks,
> Andreas
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