selinux: extended permissions for ioctls

(cherry picked from commit fa1aa143ac4a682c7f5fd52a3cf05f5a6fe44a0a)

Add extended permissions logic to selinux. Extended permissions
provides additional permissions in 256 bit increments. Extend the
generic ioctl permission check to use the extended permissions for
per-command filtering. Source/target/class sets including the ioctl
permission may additionally include a set of commands. Example:

allowxperm <source> <target>:<class> ioctl unpriv_app_socket_cmds
auditallowxperm <source> <target>:<class> ioctl priv_gpu_cmds

Where unpriv_app_socket_cmds and priv_gpu_cmds are macros
representing commonly granted sets of ioctl commands.

When ioctl commands are omitted only the permissions are checked.
This feature is intended to provide finer granularity for the ioctl
permission that may be too imprecise. For example, the same driver
may use ioctls to provide important and benign functionality such as
driver version or socket type as well as dangerous capabilities such
as debugging features, read/write/execute to physical memory or
access to sensitive data. Per-command filtering provides a mechanism
to reduce the attack surface of the kernel, and limit applications
to the subset of commands required.

The format of the policy binary has been modified to include ioctl
commands, and the policy version number has been incremented to
POLICYDB_VERSION_XPERMS_IOCTL=30 to account for the format

The extended permissions logic is deliberately generic to allow
components to be reused e.g. netlink filters

Signed-off-by: Jeff Vander Stoep <>
Acked-by: Nick Kralevich <>
Signed-off-by: Paul Moore <>
Bug: 22846070
Change-Id: I1573d6b2d0ced27e82b6447318aa5b3065021a5b
11 files changed