Jeff Vander Stoep 1089665e31 Add attribute expansion options ... This commit adds attribute expansion statements to the policy language allowing compiler defaults to be overridden. Always expands an attribute example: expandattribute { foo } true; CIL example: (expandtypeattribute (foo) true) Never expand an attribute example: expandattribute { bar } false; CIL example: (expandtypeattribute (bar) false) Adding the annotations directly to policy was chosen over other methods as it is consistent with how targeted runtime optimizations are specified in other languages. For example, in C the "inline" command. Motivation expandattribute true: Android has been moving away from a monolithic policy binary to a two part split policy representing the Android platform and the underlying vendor-provided hardware interface. The goal is a stable API allowing these two parts to be updated independently of each other. Attributes provide an important mechanism for compatibility. For example, when the vendor provides a HAL for the platform, permissions needed by clients of the HAL can be granted to an attribute. Clients need only be assigned the attribute and do not need to be aware of the underlying types and permissions being granted. Inheriting permissions via attribute creates a convenient mechanism for independence between vendor and platform policy, but results in the creation of many attributes, and the potential for performance issues when processes are clients of many HALs. [1] Annotating these attributes for expansion at compile time allows us to retain the compatibility benefits of using attributes without the performance costs. [2] expandattribute false: Commit 0be23c3f15 added the capability to aggresively remove unused attributes. This is generally useful as too many attributes assigned to a type results in lengthy policy look up times when there is a cache miss. However, removing attributes can also result in loss of information used in external tests. On Android, we're considering stripping neverallow rules from on-device policy. This is consistent with the kernel policy binary which also did not contain neverallows. Removing neverallow rules results in a 5-10% decrease in on-device policy build and load and a policy size decrease of ~250k. Neverallow rules are still asserted at build time and during device certification (CTS). If neverallow rules are absent when secilc is run, some attributes are being stripped from policy and neverallow tests in CTS may be violated. [3] This change retains the aggressive attribute stripping behavior but adds an override mechanism to preserve attributes marked as necessary. [1] https://github.com/SELinuxProject/cil/issues/9 [2] Annotating all HAL client attributes for expansion resulted in system_server's dropping from 19 attributes to 8. Because these attributes were not widely applied to other types, the final policy size change was negligible. [3] data_file_type and service_manager_type are stripped from AOSP policy when using secilc's -G option. This impacts 11 neverallow tests in CTS. Test: Build and boot Marlin with all hal_*_client attributes marked for expansion. Verify (using seinfo and sesearch) that permissions are correctly expanded from attributes to types. Test: Mark types being stripped by secilc with "preserve" and verify that they are retained in policy and applied to the same types. Signed-off-by: Jeff Vander Stoep <jeffv@google.com>		2017-05-09 12:09:46 -04:00
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cil	Add attribute expansion options	2017-05-09 12:09:46 -04:00
include	Add attribute expansion options	2017-05-09 12:09:46 -04:00
man	libsepol: constify sepol_genbools()'s boolpath parameter	2017-03-29 10:26:44 -04:00
src	Add attribute expansion options	2017-05-09 12:09:46 -04:00
tests	libsepol/tests: fix -Wwrite-strings warnings	2017-02-06 11:06:04 -05:00
utils	libsepol/utils: Fix build without system sepol.h	2017-05-05 15:48:22 -04:00
.gitignore	libsepol: build cil into libsepol	2014-08-26 08:03:31 -04:00
COPYING
Makefile	libsepol: build cil into libsepol	2014-08-26 08:03:31 -04:00
VERSION	Update VERSION and ChangeLog files for 2.6 final release.	2016-10-14 11:31:26 -04:00