linux-kernel - Re: [PATCH 16/24] init: add an init

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Date:   Tue, 21 Jul 2020 18:10:36 +0100
From:   Al Viro <viro@...iv.linux.org.uk>
To:     Christoph Hellwig <hch@....de>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        linux-kernel@...r.kernel.org, linux-raid@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, linux-api@...r.kernel.org
Subject: Re: [PATCH 16/24] init: add an init_chroot helper

On Tue, Jul 21, 2020 at 06:28:10PM +0200, Christoph Hellwig wrote:

> +int __init init_chroot(const char *filename)
> +{
> +	struct path path;
> +	int error;
> +
> +	error = kern_path(filename, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &path);
> +	if (error)
> +		return error;
> +	error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);

Matter of taste, but if we do that, I wonder if we would be better off with
	error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
	if (!error && !ns_capable(current_user_ns(), CAP_SYS_CHROOT))
		error = -EPERM;
	if (!error)
		error = security_path_chroot(&path);
	if (!error)
		set_fs_root(current->fs, &path);
	path_put(&path);
	return error;