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The access permissions and ownership or ACL of /dev/fw* character device files will typically be set based on the device type of the respective nodes, as obtained by firewire-core from descriptors in the device's configuration ROM. An example policy is to deny write permission by default but grant write permission to files of AV/C video and audio devices and IIDC video devices. The FW_CDEV_IOC_ADD_DESCRIPTOR ioctl could be used to partly subvert such a policy: Find a device file with relaxed permissions, use the ioctl to add a descriptor with AV/C marker to the local node's ROM, thus gain access to the local node's character device file. (This is only possible if there are udev scripts installed which actively relax permissions for known device types and if there is a device of such a type connected.) Accessibility of the local node's device file is relevant to host security if the host contains two or more IEEE 1394 link layer controllers which are plugged into a single bus. Therefore change the ABI to deny FW_CDEV_IOC_ADD_DESCRIPTOR if the file belongs to a remote node. (This change has no impact on known implementers of the ABI: None of them uses the ioctl yet.) Also clarify the documentation: The ioctl affects all local nodes, not just one local node. Cc: stable@kernel.org Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de> |
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| .. | ||
| fw-card.c | ||
| fw-cdev.c | ||
| fw-device.c | ||
| fw-device.h | ||
| fw-iso.c | ||
| fw-ohci.c | ||
| fw-ohci.h | ||
| fw-sbp2.c | ||
| fw-topology.c | ||
| fw-topology.h | ||
| fw-transaction.c | ||
| fw-transaction.h | ||
| Kconfig | ||
| Makefile | ||