Messages in this thread Patch in this message |  | | Date | Mon, 9 Aug 2004 00:07:27 +0200 | From | Marc Ballarin <> | Subject | Re: dynamic /dev security hole? |
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On Sun, 8 Aug 2004 09:21:15 -0700 Greg KH <greg@kroah.com> wrote:
> Patches to the udev HOWTO and FAQ are always welcome. >
How about this? The first part is a spelling fix.
(Resend, I hate "smart" features in software...)
--- udev-FAQ.orig 2004-08-08 18:42:03.639348944 +0200 +++ udev-FAQ 2004-08-08 23:14:07.895684768 +0200 @@ -23,7 +23,7 @@ - the former had stayed around for many months with maintainer claiming that everything works fine - the latter had stayed, period. - - the devfs maintainer/author disappeared and stoped maintaining + - the devfs maintainer/author disappeared and stopped maintaining the code. Q: But udev will not automatically load a driver if a /dev node is opened @@ -98,6 +98,19 @@ And don't have to be root but will get full permissions on /pendrive. This works even without udev if /udev/pendrive is replaced by /dev/sda1 +Q: Are there any security issues that I should be aware of? +A: When using dynamic device numbers, a given pair of major/minor numbers may + point to different hardware over time. If a user has permission to access a + specific device node directly and is able to create hard links to this node, + he or she can do so to create a copy of the device node. When the device is + unplugged and udev removes the device node, the user's copy remains. + If the device node is later recreated with different permissions the hard + link can still be used to access the device using the old permissions. + (The same problem exists when using PAM to change permissions on login.) + + The simplest solution is to prevent the creation of hard links by putting + /dev in a separate filesystem (tmpfs, ramfs, ...). + Q: I have other questions about udev, where do I ask them? A: The linux-hotplug-devel mailing list is the proper place for it. The address for it is linux-hotplug-devel@lists.sourceforge.net - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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