From 5487ca00d4788de367a9d099714f6df4d86ef261 Mon Sep 17 00:00:00 2001
From: Stephen Smalley <sds@tycho.nsa.gov>
Date: Mon, 10 Feb 2014 16:31:04 -0500
Subject: [PATCH] Remove several superuser capabilities from unconfined
domains.
Remove sys_ptrace and add a neverallow for it.
Remove sys_rawio and mknod, explicitly allow to kernel, init, and recovery,
and add a neverallow for them.
Remove sys_module. It can be added back where appropriate in device
policy if using a modular kernel. No neverallow since it is device
specific.
Change-Id: I1a7971db8d247fd53a8f9392de9e46250e91f89b
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
---
domain.te | 10 ++++++++++
init.te | 2 ++
kernel.te | 5 +++++
recovery.te | 4 ++++
unconfined.te | 2 +-
5 files changed, 22 insertions(+), 1 deletion(-)
diff --git a/domain.te b/domain.te
index 7cc7f133c..13ce01604 100644
--- a/domain.te
+++ b/domain.te
@@ -154,7 +154,17 @@ neverallow { domain -relabeltodomain } *:dir_file_class_set relabelto;
### neverallow rules
###
+# Limit ability to ptrace or read sensitive /proc/pid files of processes
+# with other UIDs to these whitelisted domains.
+neverallow { domain -debuggerd -vold -dumpstate -system_server } self:capability sys_ptrace;
+
+# Limit device node creation and raw I/O to these whitelisted domains.
+neverallow { domain -kernel -init -recovery -ueventd -watchdogd -healthd -vold } self:capability { sys_rawio mknod };
+
+# No domain needs mac_override as it is unused by SELinux.
neverallow domain self:capability2 mac_override;
+
+# Only recovery needs mac_admin to set contexts not defined in current policy.
neverallow { domain -recovery } self:capability2 mac_admin;
# Only init should be able to load SELinux policies.
diff --git a/init.te b/init.te
index 84fbf5a0f..efce6e7d8 100644
--- a/init.te
+++ b/init.te
@@ -7,6 +7,8 @@ relabelto_domain(init)
# add a rule to handle unlabelled mounts
allow init unlabeled:filesystem mount;
+allow init self:capability { sys_rawio mknod };
+
allow init fs_type:filesystem *;
allow init {fs_type dev_type file_type}:dir_file_class_set relabelto;
allow init kernel:security load_policy;
diff --git a/kernel.te b/kernel.te
index 106d48ec7..af107910f 100644
--- a/kernel.te
+++ b/kernel.te
@@ -16,3 +16,8 @@ allow kernel self:security setenforce;
# Set checkreqprot by init.rc prior to switching to init domain.
allow kernel self:security setcheckreqprot;
+
+# For operations performed by kernel or init prior to switching to init domain.
+## TODO: Investigate whether it is safe to remove these
+allow kernel self:capability { sys_rawio mknod };
+auditallow kernel self:capability { sys_rawio mknod };
diff --git a/recovery.te b/recovery.te
index 37d645593..ea444c4bb 100644
--- a/recovery.te
+++ b/recovery.te
@@ -13,3 +13,7 @@ allow recovery fs_type:filesystem *;
allow recovery self:process execmem;
allow recovery ashmem_device:chr_file execute;
allow recovery tmpfs:file rx_file_perms;
+
+## TODO: Investigate whether it is safe to remove these
+allow recovery self:capability { sys_rawio mknod };
+auditallow recovery self:capability { sys_rawio mknod };
diff --git a/unconfined.te b/unconfined.te
index ac0de840f..8415ada78 100644
--- a/unconfined.te
+++ b/unconfined.te
@@ -16,7 +16,7 @@
# The use of this template is discouraged.
######################################################
-allow unconfineddomain self:capability *;
+allow unconfineddomain self:capability ~{ sys_ptrace sys_rawio mknod sys_module };
allow unconfineddomain self:capability2 ~{ mac_override mac_admin };
allow unconfineddomain kernel:security ~{ load_policy setenforce setcheckreqprot };
allow unconfineddomain kernel:system *;
--
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