From d90d001a780a96bdeb68aae5806ddcd4aaac8c11 Mon Sep 17 00:00:00 2001
From: Nick Kralevich <nnk@google.com>
Date: Tue, 7 Aug 2018 15:13:05 +0000
Subject: [PATCH] Revert "Remove legacy execmod access."
This reverts commit 0f11ffccf907b000213d76eccb22a84ac73c19e5.
Reason for revert: libmono crashes
Bug: 112292089
Bug: 111544476
Test: policy compiles, device boots
Change-Id: I064090aa9337cf17b80cd2c9af9342df851a3b27
---
private/untrusted_app_all.te | 10 +++++++++-
public/domain.te | 18 +++++++++++++++---
2 files changed, 24 insertions(+), 4 deletions(-)
diff --git a/private/untrusted_app_all.te b/private/untrusted_app_all.te
index fdda73031..6ec21831f 100644
--- a/private/untrusted_app_all.te
+++ b/private/untrusted_app_all.te
@@ -20,9 +20,13 @@
### Note that rules that should apply to all untrusted apps must be in app.te or also
### added to ephemeral_app.te.
+# Legacy text relocations
+allow untrusted_app_all apk_data_file:file execmod;
+
# Some apps ship with shared libraries and binaries that they write out
# to their sandbox directory and then execute.
allow untrusted_app_all { app_data_file privapp_data_file }:file { rx_file_perms };
+allow untrusted_app_all app_data_file:file execmod;
# Executing files from an application home directory violates
# W^X (https://en.wikipedia.org/wiki/W%5EX) constraints (loading executable code
@@ -34,7 +38,7 @@ auditallow untrusted_app_all app_data_file:file { execute execute_no_trans };
allow untrusted_app_all asec_apk_file:file r_file_perms;
allow untrusted_app_all asec_apk_file:dir r_dir_perms;
# Execute libs in asec containers.
-allow untrusted_app_all asec_public_file:file { execute };
+allow untrusted_app_all asec_public_file:file { execute execmod };
# Used by Finsky / Android "Verify Apps" functionality when
# running "adb install foo.apk".
@@ -153,6 +157,10 @@ userdebug_or_eng(`
}:{ dir file lnk_file } { getattr open read };
')
+# Temporary auditing to get data on what apps use execmod.
+# TODO(b/111544476) Remove this and deny the permission if feasible.
+auditallow untrusted_app_all { apk_data_file app_data_file asec_public_file }:file execmod;
+
# Attempts to write to system_data_file is generally a sign
# that apps are attempting to access encrypted storage before
# the ACTION_USER_UNLOCKED intent is delivered. Suppress this
diff --git a/public/domain.te b/public/domain.te
index 4e306227f..85b8ff204 100644
--- a/public/domain.te
+++ b/public/domain.te
@@ -1114,14 +1114,26 @@ neverallow * { file_type fs_type dev_type }:{ lnk_file fifo_file sock_file } mou
# su itself execute su.
neverallow { domain userdebug_or_eng(`-dumpstate -shell -su') } su_exec:file no_x_file_perms;
+# Do not allow the introduction of new execmod rules. Text relocations
+# and modification of executable pages are unsafe.
+# The only exceptions are for NDK text relocations associated with
+# https://code.google.com/p/android/issues/detail?id=23203
+# which, long term, need to go away.
+neverallow * {
+ file_type
+ -apk_data_file
+ -app_data_file
+ -asec_public_file
+}:file execmod;
+
# Do not allow making the stack or heap executable.
# We would also like to minimize execmem but it seems to be
# required by some device-specific service domains.
neverallow * self:process { execstack execheap };
-# Do not allow the introduction of execmod rules. Text relocations
-# and modification of executable pages are unsafe.
-neverallow * file_type:file execmod;
+# prohibit non-zygote spawned processes from using shared libraries
+# with text relocations. b/20013628 .
+neverallow { domain -untrusted_app_all } file_type:file execmod;
neverallow { domain -init } proc:{ file dir } mounton;
--
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