22fc04103b
Support the inseretion of the public key from pem files into the mac_permissions.xml file at build time. Change-Id: Ia42b6cba39bf93723ed3fb85236eb8f80a08962a
102 lines
4.3 KiB
Text
102 lines
4.3 KiB
Text
Policy Generation:
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Additional, per device, policy files can be added into the
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policy build.
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They can be configured through the use of three variables,
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they are:
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1. BOARD_SEPOLICY_REPLACE
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2. BOARD_SEPOLICY_UNION
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3. BOARD_SEPOLICY_DIRS
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The variables should be set in the BoardConfig.mk file in
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the device or vendor directories.
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BOARD_SEPOLICY_UNION is a list of files that will be
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"unioned", IE concatenated, at the END of their respective
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file in external/sepolicy. Note, to add a unique file you
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would use this variable.
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BOARD_SEPOLICY_REPLACE is a list of files that will be
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used instead of the corresponding file in external/sepolicy.
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BOARD_SEPOLICY_DIRS contains a list of directories to search
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for BOARD_SEPOLICY_UNION and BOARD_SEPOLICY_REPLACE files. Order
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matters in this list.
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eg.) If you have BOARD_SEPOLICY_UNION := widget.te and have 2
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instances of widget.te files on BOARD_SEPOLICY_DIRS search path.
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The first one found (at the first search dir containing the file)
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gets processed first.
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Reviewing out/target/product/<device>/etc/sepolicy_intermediates/policy.conf
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will help sort out ordering issues.
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It is an error to specify a BOARD_POLICY_REPLACE file that does
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not exist in external/sepolicy.
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It is an error to specify a BOARD_POLICY_REPLACE file that appears
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multiple times on the policy search path defined by BOARD_SEPOLICY_DIRS.
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eg.) if you specify shell.te in BOARD_SEPOLICY_REPLACE and
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BOARD_SEPOLICY_DIRS is set to
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"vendor/widget/common/sepolicy device/widget/x/sepolicy" and shell.te
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appears in both locations, it is an error.
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It is an error to specify the same file name in both
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BOARD_POLICY_REPLACE and BOARD_POLICY_UNION.
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It is an error to specify a BOARD_SEPOLICY_DIRS that has no entries when
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specifying BOARD_SEPOLICY_REPLACE.
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Example Usage:
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From the Tuna device BoardConfig.mk, device/samsung/tuna/BoardConfig.mk
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BOARD_SEPOLICY_DIRS := \
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device/samsung/tuna/sepolicy
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BOARD_SEPOLICY_UNION := \
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genfs_contexts \
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file_contexts \
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sepolicy.te
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SPECIFIC POLICY FILE INFORMATION
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mac_permissions.xml:
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ABOUT:
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The mac_permissions.xml file is used for controlling the mmac solutions
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as well as mapping a public base16 signing key with an arbitrary seinfo
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string. Details of the files contents can be found in a comment at the
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top of that file. The seinfo string, previously mentioned, is the same string
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that is referenced in seapp_contexts.
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This file can be replaced through BOARD_SEPOLICY_REPLACE containing the
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value "mac_permissions.xml", however, appending (UNION) does NOT exist
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and will cause a build time failure. It is important to note the final
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processed version of this file is stripped of comments and whitespace.
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This is to preserve space on the system.img. If one wishes to view it in
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a more human friendly format, the "tidy" or "xmllint" command will assist
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you.
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TOOLING:
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insertkeys.py
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Is a helper script for mapping arbitrary tags in the signature stanzas of
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mac_permissions.xml to public keys found in pem files. This script takes
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a mac_permissions.xml file and configuration file in order to operate.
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Details of the configuration file (keys.conf) can be found in the subsection
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keys.conf. This script is also responsible for stipping the comments and
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whitespace from the xml file.
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keys.conf
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The keys.conf file is used for controlling the mapping of "tags" found in
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the mac_permissions.xml signature stanzas with actual public keys found in
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pem files. The configuration file can be used in BOARD_SEPOLICY_UNION and
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BOARD_SEPOLICY_REPLACE variables and is processed via m4.
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The script allows for mapping any string contained in TARGET_BUILD_VARIANT
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with specific path to a pem file. Typically TARGET_BUILD_VARIANT is either
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user, eng or userdebug. Additionally, one can specify "ALL" to map a path to
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any string specified in TARGET_BUILD_VARIANT. All tags are matched verbatim
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and all options are matched lowercase. The options are "tolowered" automatically
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for the user, it is convention to specify tags and options in all uppercase
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and tags start with @.
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NOTE: The pem files are base64 encoded and PackageManagerService, mac_permissions.xml
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and setool all use base16 encodings.
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