commit | 171c5c63afc4c30efded0f3830438525d6cdf88c | [log] [tgz] |
---|---|---|
author | Priyanka Advani (xWF) <padvani@google.com> | Thu Nov 07 23:41:40 2024 +0000 |
committer | Gerrit Code Review <noreply-gerritcodereview@google.com> | Thu Nov 07 23:41:40 2024 +0000 |
tree | f51802cd54b0573cc0cc74254ad0d314701c0422 | |
parent | 116aa1a1a16c52f3036d238711579abebb205263 [diff] |
Revert "Add property accesses to gatekeeper, keymint policies" Revert submission 3325533-2024-10-29-schuffelen-sepolicy Reason for revert: Droidmonitor created revert due to b/377974784. Will be verifying through ABTD before submission. Reverted changes: /q/submissionid:3325533-2024-10-29-schuffelen-sepolicy Change-Id: I912f827e76b1c59cc550a10ba7324fd848ccfe6e
This directory contains the core Android SELinux policy configuration. It defines the domains and types for the AOSP services and apps common to all devices. Device-specific policy should be placed under a separate device/<vendor>/<board>/sepolicy
subdirectory and linked into the policy build as described below.
Additional, per device, policy files can be added into the policy build. These files should have each line including the final line terminated by a newline character (0x0A
). This will allow files to be concatenated and processed whenever the m4
(1) macro processor is called by the build process. Adding the newline will also make the intermediate text files easier to read when debugging build failures. The sets of file, service and property contexts files will automatically have a newline inserted between each file as these are common failure points.
These device policy files can be configured through the use of the BOARD_VENDOR_SEPOLICY_DIRS
variable. This variable should be set in the BoardConfig.mk file in the device or vendor directories.
BOARD_VENDOR_SEPOLICY_DIRS
contains a list of directories to search for additional policy files. Order matters in this list. For example, if you have 2 instances of widget.te files in the BOARD_VENDOR_SEPOLICY_DIRS
search path, then the first one found (at the first search dir containing the file) will be concatenated first. Reviewing out/target/product/<device>/obj/ETC/vendor_sepolicy.conf_intermediates/vendor_sepolicy.conf
will help sort out ordering issues.
Example BoardConfig.mk
Usage: From the Tuna device BoardConfig.mk
, device/samsung/tuna/BoardConfig.mk
BOARD_VENDOR_SEPOLICY_DIRS += device/samsung/tuna/sepolicy
Alongside vendor sepolicy dirs, OEMs can also amend the public and private policy of the product and system_ext partitions:
SYSTEM_EXT_PUBLIC_SEPOLICY_DIRS += device/acme/roadrunner-sepolicy/systemext/public SYSTEM_EXT_PRIVATE_SEPOLICY_DIRS += device/acme/roadrunner-sepolicy/systemext/private PRODUCT_PUBLIC_SEPOLICY_DIRS += device/acme/roadrunner-sepolicy/product/public PRODUCT_PRIVATE_SEPOLICY_DIRS += device/acme/roadrunner-sepolicy/product/private
The old BOARD_PLAT_PUBLIC_SEPOLICY_DIR
and BOARD_PLAT_PRIVATE_SEPOLICY_DIR
variables have been deprecated in favour of SYSTEM_EXT_*
.
Additionally, OEMs can specify BOARD_SEPOLICY_M4DEFS
to pass arbitrary m4
definitions during the build. A definition consists of a string in the form of macro-name=value
. Spaces must NOT be present. This is useful for building modular policies, policy generation, conditional file paths, etc. It is supported in the following file types:
*.te
and SELinux policy files as passed to checkpolicy
file_contexts
service_contexts
property_contexts
keys.conf
Example BoardConfig.mk Usage:
BOARD_SEPOLICY_M4DEFS += btmodule=foomatic \ btdevice=/dev/gps
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.
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.
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.
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 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 @. The option arguments can also use environment variables via the familiar $VARIABLE
syntax. This is often useful for setting a location to ones release keys.
Often times, one will need to integrate an application that was signed by a separate organization and may need to extract the pem file for the insertkeys/keys.conf
tools. Extraction of the public key in the pem format is possible via openssl
. First you need to unzip the apk, once it is unzipped, cd
into the META_INF
directory and then execute
openssl pkcs7 -inform DER -in CERT.RSA -out CERT.pem -outform PEM -print_certs
On some occasions CERT.RSA
has a different name, and you will need to adjust for that. After extracting the pem, you can rename it, and configure keys.conf
and mac_permissions.xml
to pick up the change. You MUST open the generated pem file in a text editor and strip out anything outside the opening and closing scissor lines. Failure to do so WILL cause a compile time issue thrown by insertkeys.py
NOTE: The pem files are base64 encoded and PackageManagerService
, mac_permissions.xml
and setool
all use base16 encodings.