From 1851dcb2ee5245b0e06974500bec8d93674b6114 Mon Sep 17 00:00:00 2001 From: Inseob Kim Date: Thu, 7 Apr 2022 22:44:42 +0900 Subject: [PATCH] Convert README to README.md Just a format change. The contents are copy-and-pasted as-is. Bug: 196944893 Test: N/A Change-Id: I4d898d5bae784a8cf2087c7fdeaff7493eb2aa62 --- README | 114 ---------------------------------------------------- README.md | 117 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 117 insertions(+), 114 deletions(-) delete mode 100644 README create mode 100644 README.md diff --git a/README b/README deleted file mode 100644 index f14ac67e6..000000000 --- a/README +++ /dev/null @@ -1,114 +0,0 @@ -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///sepolicy subdirectory and linked -into the policy build as described below. - -Policy Generation: - -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//obj/ETC/sepolicy_intermediates/policy.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: - * All *.te and SE Linux 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 - -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. - - 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 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. diff --git a/README.md b/README.md new file mode 100644 index 000000000..16d7e453a --- /dev/null +++ b/README.md @@ -0,0 +1,117 @@ +# Android SEPolicy + +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///sepolicy` subdirectory and linked +into the policy build as described below. + +## Policy Generation + +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//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: +* All `*.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 + +## SPECIFIC POLICY FILE INFORMATION + +### mac_permissions.xml +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. + +### 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 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.