On Mon, 2004-08-23 at 08:08 -0400, Alan Cox wrote: > On Mon, Aug 23, 2004 at 12:50:26PM +0200, David Zeuthen wrote: > > But.. without access to block devices, how do propose we detect media > > changes then? > > If you don't have permission you leave it alone would be the obvious answer. > There is another problem with opening all the devices and polling too. I have > 17 CD-ROM slots attached to one PC. As they are multichangers it'll take you > about 2 minutes to poll them all as well as ruining anything they were doing. > > Any multichanger shouldn't be polled this way. > You can just blacklist polling on these using device information files (property name is storage.media_check_enabled). I don't have a multichanger and I don't think this is common hardware either so I haven't been able to blacklist them. > > Sure, it's an attack vector, however keep in mind that hald uses D-BUS > > as IPC and D-BUS is specifically designed to be secure and validate the > > messages that come through. > > and sendmail was formally audited and BR14 had no bugs. Adding attack vectors > is bad but if HAL only has permissions for the drives it needs then it doesnt > seem too big a problem. > HAL needs to run as root to invoke callouts. See this diagram http://freedesktop.org/~david/hal-spec/hal-spec.html#ov_hal_linux26 and surrounding text for more information, background etc. Presumably we can move to callouts (such as fstab-sync) to a separate helper process and by then drop a lot of privileges etc. Until that happens we need to run as root because the callouts may need privileges. > > > Also one of my machines is logging the following repeatedly: > > > Aug 23 20:31:14 community kernel: hdc: packet command error: error=0x50 > > > Aug 23 20:31:14 community kernel: cdrom: open failed. > > Hal is triggering errors trying to open drives with no media. Probably hal > should keep the CD-ROM open, flip doorlock back off and use ATA media > sense packets. Thats horrible stuff to do unfortunately. > Sure, care to send a patch to the hal mailing list or some pointers on how to implement this? Thanks, David
