Date: Sun, 4 Jan 2009 16:23:29 +0100 (CET) From: Stefan Richter Subject: firewire: cdev: restrict broadcast write requests to Units Space We don't want random users write to Memory Space (e.g. PCs with physical DMA filters down) or to core CSRs like Reset_Start. This does not protect SBP-2 target CSRs. But properly behaving SBP-2 targets ignore broadcast write requests to these registers, and the maximum damage which can happen with laxer targets is DOS. But there are ways to create DOS situations anyway if there are devices with weak device file permissions (like audio/video devices) present at the same bus as an SBP-2 target. Signed-off-by: Stefan Richter --- drivers/firewire/fw-cdev.c | 4 ++++ 1 file changed, 4 insertions(+) Index: linux/drivers/firewire/fw-cdev.c =================================================================== --- linux.orig/drivers/firewire/fw-cdev.c +++ linux/drivers/firewire/fw-cdev.c @@ -1245,6 +1245,10 @@ static int ioctl_send_broadcast_request( return -EINVAL; } + /* Security policy: Only allow accesses to Units Space. */ + if (request->offset < CSR_REGISTER_BASE + CSR_CONFIG_ROM_END) + return -EACCES; + return init_request(client, request, LOCAL_BUS | 0x3f, SCODE_100); }