linux-kernel - Re: [patch 11/14] vfs: move executable checking into ->permission()

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Message-Id: <1211393793.7486.15.camel@localhost>
Date:	Wed, 21 May 2008 14:16:33 -0400
From:	Trond Myklebust <trond.myklebust@....uio.no>
To:	Miklos Szeredi <miklos@...redi.hu>
Cc:	linux-fsdevel@...r.kernel.org, hch@...radead.org,
	viro@...IV.linux.org.uk, linux-kernel@...r.kernel.org
Subject: Re: [patch 11/14] vfs: move executable checking into ->permission()

On Wed, 2008-05-21 at 19:15 +0200, Miklos Szeredi wrote:

> +/**
> + * exec_permission - check for general execute permission on file
> + * @inode:	inode to check access rights for
> + * @mask:	right to check for
> + *
> + * Exec permission on a regular file is denied if none of the execute
> + * bits are set.
> + *
> + * This needs to be called by filesystems which define a
> + * ->permission() method, and don't call generic_permission().
> + */
> +int exec_permission(struct inode *inode, int mask)
> +{
> +	if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode) &&
> +	    !(inode->i_mode & S_IXUGO))
> +		return -EACCES;
> +
> +	return 0;
> +}

Hmm... What if !(mask & MAY_EXEC)? AFAICS, the above will return 0.
A better approach would be to use something like

	if (!(mask & MAY_EXEC))
		return -EACCES;
	if (S_ISREG(inode->i_mode) && !(inode->i_mode & S_IXUGO))
		return -EACCES;
	return 0;



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