Policy Generation: Additional, per device, policy files can be added into the policy build. They can be configured through the use of three variables, they are: 1. BOARD_SEPOLICY_REPLACE 2. BOARD_SEPOLICY_UNION 3. BOARD_SEPOLICY_DIRS 4. BOARD_SEPOLICY_IGNORE The variables should be set in the BoardConfig.mk file in the device or vendor directories. BOARD_SEPOLICY_UNION is a list of files that will be "unioned", IE concatenated, at the END of their respective file in external/sepolicy. Note, to add a unique file you would use this variable. BOARD_SEPOLICY_REPLACE is a list of files that will be used instead of the corresponding file in external/sepolicy. BOARD_SEPOLICY_DIRS contains a list of directories to search for BOARD_SEPOLICY_UNION and BOARD_SEPOLICY_REPLACE files. Order matters in this list. eg.) If you have BOARD_SEPOLICY_UNION := widget.te and have 2 instances of widget.te files on BOARD_SEPOLICY_DIRS search path. The first one found (at the first search dir containing the file) gets processed first. Reviewing out/target/product/<device>/etc/sepolicy_intermediates/policy.conf will help sort out ordering issues. It is an error to specify a BOARD_POLICY_REPLACE file that does not exist in external/sepolicy. It is an error to specify a BOARD_POLICY_REPLACE file that appears multiple times on the policy search path defined by BOARD_SEPOLICY_DIRS. eg.) if you specify shell.te in BOARD_SEPOLICY_REPLACE and BOARD_SEPOLICY_DIRS is set to "vendor/widget/common/sepolicy device/widget/x/sepolicy" and shell.te appears in both locations, it is an error. Unless it is in BOARD_SEPOLICY_IGNORE to be filtered out. See BOARD_SEPOLICY_IGNORE for more details. It is an error to specify the same file name in both BOARD_POLICY_REPLACE and BOARD_POLICY_UNION. It is an error to specify a BOARD_SEPOLICY_DIRS that has no entries when specifying BOARD_SEPOLICY_REPLACE. BOARD_SEPOLICY_IGNORE is a list of paths (directory + filename) of files that are not to be included in the resulting policy. This list is passed to filter-out to remove any paths you may want to ignore. This is useful if you have numerous config directories that contain a file and you want to NOT include a particular file in your resulting policy file, either by UNION or REPLACE. Eg.) Suppose the following: BOARD_SEPOLICY_DIRS := X Y BOARD_SEPOLICY_REPLACE := A BOARD_SEPOLICY_IGNORE := X/A Directories X and Y contain A. The resulting policy is created by using Y/A only, thus X/A was ignored. Example BoardConfig.mk Usage: From the Tuna device BoardConfig.mk, device/samsung/tuna/BoardConfig.mk BOARD_SEPOLICY_DIRS := \ device/samsung/tuna/sepolicy BOARD_SEPOLICY_UNION := \ genfs_contexts \ file_contexts \ sepolicy.te SPECIFIC POLICY FILE INFORMATION mac_permissions.xml: ABOUT: The mac_permissions.xml file is used for controlling the mmac solutions as well as mapping a public base16 signing key with an arbitrary seinfo string. Details of the files contents can be found in a comment at the top of that file. The seinfo string, previously mentioned, is the same string that is referenced in seapp_contexts. This file can be replaced through BOARD_SEPOLICY_REPLACE containing the value "mac_permissions.xml", or appended to by using the BOARD_SEPOLICY_UNION variable. It is important to note the final processed version of this file is stripped of comments and whitespace. This is to preserve space on the system.img. If one wishes to view it in a more human friendly format, the "tidy" or "xmllint" command will assist you. TOOLING: insertkeys.py Is a helper script for mapping arbitrary tags in the signature stanzas of mac_permissions.xml to public keys found in pem files. This script takes a mac_permissions.xml file(s) and configuration file in order to operate. Details of the configuration file (keys.conf) can be found in the subsection keys.conf. This tool is also responsible for stripping the comments and whitespace during processing. keys.conf The keys.conf file is used for controlling the mapping of "tags" found in the mac_permissions.xml signature stanzas with actual public keys found in pem files. The configuration file can be used in BOARD_SEPOLICY_UNION and BOARD_SEPOLICY_REPLACE variables and is processed via m4. The script allows for mapping any string contained in TARGET_BUILD_VARIANT with specific path to a pem file. Typically TARGET_BUILD_VARIANT is either user, eng or userdebug. Additionally, one can specify "ALL" to map a path to any string specified in TARGET_BUILD_VARIANT. All tags are matched verbatim and all options are matched lowercase. The options are "tolowered" automatically for the user, it is convention to specify tags and options in all uppercase and tags start with @. NOTE: The pem files are base64 encoded and PackageManagerService, mac_permissions.xml and setool all use base16 encodings.