linux-kernel - Re: [patch 00/13] devtmpfs patches

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <m1k54nfv9h.fsf@fess.ebiederm.org>
Date:	Mon, 11 May 2009 09:40:26 -0700
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	Kay Sievers <kay.sievers@...y.org>
Cc:	Arjan van de Ven <arjan@...radead.org>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Peter Zijlstra <peterz@...radead.org>,
	Greg KH <gregkh@...e.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Fabio Comolli <fabio.comolli@...il.com>,
	Greg KH <greg@...ah.com>, linux-kernel@...r.kernel.org
Subject: Re: [patch 00/13] devtmpfs patches

Kay Sievers <kay.sievers@...y.org> writes:

> Maybe you should just give it a try, apply the patch, and bring it up
> on a box with init=/bin/sh, look at /dev, load some modules and look
> at /dev again - and see the beauty. I'm pretty sure, when you've seen
> it for real, you never want to go back to static nodes or whatever
> other bad hacks to bootstrap /dev.

After it sunk in what you had said I had to go look at your patch.
You do magically and backwards incompatibly mount on top of /dev.

That part does not work, and who knows what static /dev setup you break.

The goal for kernel compile options is that they do not affect the
kernels behavior.  The behavior in devmtmpfs clearly does not match
that rule.  The kernel acts very different with it compiled in
and with it not compiled in. So that section of the code deserves.

Nacked-by: "Eric W. Biederman" <ebiederm@...ssion.com>

+/* After the root filesystem is mounted by the kernel at /root, or the
+ * initramfs in extracted at /root, this tmpfs will be mounted at /root/dev.
+ */
+int devtmpfs_mount(const char *mountpoint)
+{
+	struct path path;
+	int err;
+
+	if (!dev_mnt)
+		return 0;
+
+	err = kern_path(mountpoint, LOOKUP_FOLLOW, &path);
+	if (err)
+		return err;
+	err = do_add_mount(dev_mnt, &path, 0, NULL);
+	if (err)
+		printk(KERN_INFO "devtmpfs: error mounting %i\n", err);
+	else
+		printk(KERN_INFO "devtmpfs: mounted\n");
+	path_put(&path);
+	return err;
+}
+

--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -414,7 +414,7 @@ void __init prepare_namespace(void)
 
 	mount_root();
 out:
+	devtmpfs_mount("dev");
 	sys_mount(".", "/", NULL, MS_MOVE, NULL);
 	sys_chroot(".");
 }
-
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/