From 356f4be679544363466dad93e7bee68b2a6f2cf0 Mon Sep 17 00:00:00 2001
From: Stephen Smalley <sds@tycho.nsa.gov>
Date: Fri, 23 May 2014 11:26:19 -0400
Subject: [PATCH] Restrict requesting contexts other than policy-defined
 defaults.

Writing to the /proc/self/attr files (encapsulated by the libselinux
set*con functions) enables a program to request a specific security
context for various operations instead of the policy-defined defaults.
The security context specified using these calls is checked by an
operation-specific permission, e.g. dyntransition for setcon,
transition for setexeccon, create for setfscreatecon or
setsockcreatecon, but the ability to request a context at all
is controlled by a process permission.  Omit these permissions from
domain.te and only add them back where required so that only specific
domains can even request a context other than the default defined by
the policy.

Change-Id: I6a2fb1279318625a80f3ea8e3f0932bdbe6df676
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
---
 adbd.te     | 1 +
 domain.te   | 2 +-
 init.te     | 6 ++++++
 kernel.te   | 2 ++
 recovery.te | 3 +++
 runas.te    | 1 +
 ueventd.te  | 3 +++
 zygote.te   | 1 +
 8 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/adbd.te b/adbd.te
index 44607c712..4b6764759 100644
--- a/adbd.te
+++ b/adbd.te
@@ -3,6 +3,7 @@
 type adbd, domain;
 
 userdebug_or_eng(`
+  allow adbd self:process setcurrent;
   allow adbd su:process dyntransition;
 ')
 
diff --git a/domain.te b/domain.te
index 5fef04b29..f7e86923f 100644
--- a/domain.te
+++ b/domain.te
@@ -11,7 +11,7 @@ allow domain tmpfs:file { read getattr };
 allow domain tmpfs:dir r_dir_perms;
 
 # Intra-domain accesses.
-allow domain self:process ~{ execmem execstack execheap ptrace };
+allow domain self:process ~{ execmem execstack execheap ptrace setexec setfscreate setcurrent setkeycreate setsockcreate };
 allow domain self:fd use;
 allow domain self:dir r_dir_perms;
 allow domain self:lnk_file r_file_perms;
diff --git a/init.te b/init.te
index 3441dd0c3..e94ca4784 100644
--- a/init.te
+++ b/init.te
@@ -27,3 +27,9 @@ allow init watchdogd:process transition;
 # the directory as part of a recursive restorecon.
 allow init keystore_data_file:dir { open create read getattr setattr search };
 allow init keystore_data_file:file { getattr };
+
+# Use setexeccon(), setfscreatecon(), and setsockcreatecon().
+# setexec is for services with seclabel options.
+# setfscreate is for labeling directories and socket files.
+# setsockcreate is for labeling local/unix domain sockets.
+allow init self:process { setexec setfscreate setsockcreate };
diff --git a/kernel.te b/kernel.te
index 0048a626e..f2405e4fd 100644
--- a/kernel.te
+++ b/kernel.te
@@ -1,6 +1,8 @@
 # Life begins with the kernel.
 type kernel, domain;
 
+# setcon to init domain.
+allow kernel self:process setcurrent;
 allow kernel init:process dyntransition;
 
 # The kernel is unconfined.
diff --git a/recovery.te b/recovery.te
index cfec16104..c1329833a 100644
--- a/recovery.te
+++ b/recovery.te
@@ -15,3 +15,6 @@ allow recovery dev_type:blk_file rw_file_perms;
 allow recovery self:process execmem;
 allow recovery ashmem_device:chr_file execute;
 allow recovery tmpfs:file rx_file_perms;
+
+# Use setfscreatecon() to label files for OTA updates.
+allow recovery self:process setfscreate;
diff --git a/runas.te b/runas.te
index 8648ee711..8cc0eeac9 100644
--- a/runas.te
+++ b/runas.te
@@ -21,4 +21,5 @@ allow runas self:capability { setuid setgid };
 # read /seapp_contexts and /data/security/seapp_contexts
 security_access_policy(runas)
 selinux_check_context(runas) # validate context
+allow runas self:process setcurrent;
 allow runas non_system_app_set:process dyntransition; # setcon
diff --git a/ueventd.te b/ueventd.te
index babebe04d..25460de2b 100644
--- a/ueventd.te
+++ b/ueventd.te
@@ -20,3 +20,6 @@ allow ueventd dev_type:blk_file { create setattr unlink };
 allow ueventd self:netlink_kobject_uevent_socket create_socket_perms;
 allow ueventd efs_file:dir search;
 allow ueventd efs_file:file r_file_perms;
+
+# Use setfscreatecon() to label /dev directories and files.
+allow ueventd self:process setfscreate;
diff --git a/zygote.te b/zygote.te
index 4d169f358..da3a03723 100644
--- a/zygote.te
+++ b/zygote.te
@@ -9,6 +9,7 @@ allow zygote self:capability { dac_override setgid setuid fowner chown };
 # Drop capabilities from bounding set.
 allow zygote self:capability setpcap;
 # Switch SELinux context to app domains.
+allow zygote self:process setcurrent;
 allow zygote system_server:process dyntransition;
 allow zygote appdomain:process dyntransition;
 # Allow zygote to read app /proc/pid dirs (b/10455872)
-- 
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