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132 lines
4.9 KiB
Diff
132 lines
4.9 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Daniel Micay <danielmicay@gmail.com>
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Date: Fri, 29 Jul 2016 14:48:19 -0400
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Subject: [PATCH] restrict access to timing information in /proc
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These APIs expose sensitive information via timing side channels. This
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leaves access via the adb shell intact along with the current uses by
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dumpstate, init and system_server.
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The /proc/interrupts and /proc/stat files were covered in this paper:
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https://www.lightbluetouchpaper.org/2016/07/29/yet-another-android-side-channel/
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The /proc/softirqs, /proc/timer_list and /proc/timer_stats files are
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also relevant.
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Access to /proc has been greatly restricted since then, with untrusted
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apps no longer having direct access to these, but stricter restrictions
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beyond that would be quite useful.
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Change-Id: Ibed16674856569d26517e5729f0f194b830cfedd
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---
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dumpstate.te | 1 +
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file.te | 3 +++
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genfs_contexts | 5 +++++
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init.te | 3 +++
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shell.te | 3 +++
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system_server.te | 3 +++
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6 files changed, 18 insertions(+)
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diff --git a/dumpstate.te b/dumpstate.te
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index 0b1f97bd6..71c12461c 100644
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--- a/dumpstate.te
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+++ b/dumpstate.te
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@@ -188,6 +188,7 @@ allow dumpstate debugfs_tracing:dir r_dir_perms;
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allow dumpstate debugfs_tracing:file rw_file_perms;
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allow dumpstate debugfs_trace_marker:file getattr;
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allow dumpstate atrace_exec:file rx_file_perms;
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+allow dumpstate proc_interrupts:file r_file_perms;
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# Access to /data/media.
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# This should be removed if sdcardfs is modified to alter the secontext for its
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diff --git a/file.te b/file.te
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index 446c1829c..6099eb581 100644
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--- a/file.te
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+++ b/file.te
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@@ -13,10 +13,13 @@ type usermodehelper, fs_type, sysfs_type;
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type qtaguid_proc, fs_type, mlstrustedobject;
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type proc_bluetooth_writable, fs_type;
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type proc_cpuinfo, fs_type;
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+type proc_interrupts, fs_type;
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type proc_iomem, fs_type;
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type proc_meminfo, fs_type;
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type proc_net, fs_type;
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+type proc_stat, fs_type;
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type proc_sysrq, fs_type;
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+type proc_timer, fs_type;
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type proc_uid_cputime_showstat, fs_type;
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type proc_uid_cputime_removeuid, fs_type;
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type selinuxfs, fs_type, mlstrustedobject;
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diff --git a/genfs_contexts b/genfs_contexts
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index 7597b4c6d..3bf0282a2 100644
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--- a/genfs_contexts
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+++ b/genfs_contexts
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@@ -2,11 +2,14 @@
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genfscon rootfs / u:object_r:rootfs:s0
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# proc labeling can be further refined (longest matching prefix).
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genfscon proc / u:object_r:proc:s0
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+genfscon proc /interrupts u:object_r:proc_interrupts:s0
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genfscon proc /iomem u:object_r:proc_iomem:s0
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genfscon proc /meminfo u:object_r:proc_meminfo:s0
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genfscon proc /net u:object_r:proc_net:s0
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genfscon proc /net/xt_qtaguid/ctrl u:object_r:qtaguid_proc:s0
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genfscon proc /cpuinfo u:object_r:proc_cpuinfo:s0
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+genfscon proc /softirqs u:object_r:proc_timer:s0
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+genfscon proc /stat u:object_r:proc_stat:s0
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genfscon proc /sysrq-trigger u:object_r:proc_sysrq:s0
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genfscon proc /sys/fs/protected_fifos u:object_r:proc_security:s0
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genfscon proc /sys/fs/protected_hardlinks u:object_r:proc_security:s0
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@@ -25,6 +28,8 @@ genfscon proc /sys/kernel/usermodehelper u:object_r:usermodehelper:s0
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genfscon proc /sys/net u:object_r:proc_net:s0
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genfscon proc /sys/vm/mmap_min_addr u:object_r:proc_security:s0
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genfscon proc /sys/vm/drop_caches u:object_r:proc_drop_caches:s0
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+genfscon proc /timer_list u:object_r:proc_timer:s0
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+genfscon proc /timer_stats u:object_r:proc_timer:s0
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genfscon proc /uid_cputime/show_uid_stat u:object_r:proc_uid_cputime_showstat:s0
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genfscon proc /uid_cputime/remove_uid_range u:object_r:proc_uid_cputime_removeuid:s0
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diff --git a/init.te b/init.te
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index 9bc78d173..4e14d97e1 100644
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--- a/init.te
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+++ b/init.te
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@@ -155,6 +155,9 @@ allow init self:capability net_admin;
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# Write to /proc/sysrq-trigger.
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allow init proc_sysrq:file w_file_perms;
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+# Read /proc/stat for bootchart.
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+allow init proc_stat:file r_file_perms;
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+
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# Reboot.
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allow init self:capability sys_boot;
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diff --git a/shell.te b/shell.te
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index 3e95b4687..69e9c113a 100644
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--- a/shell.te
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+++ b/shell.te
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@@ -96,7 +96,10 @@ allow shell { service_manager_type -gatekeeper_service -netd_service }:service_m
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# allow shell to look through /proc/ for ps, top, netstat
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r_dir_file(shell, proc)
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r_dir_file(shell, proc_net)
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+allow shell proc_interrupts:file r_file_perms;
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allow shell proc_meminfo:file r_file_perms;
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+allow shell proc_stat:file r_file_perms;
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+allow shell proc_timer:file r_file_perms;
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r_dir_file(shell, cgroup)
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allow shell domain:dir { search open read getattr };
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allow shell domain:{ file lnk_file } { open read getattr };
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diff --git a/system_server.te b/system_server.te
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index db59b6573..334cb9144 100644
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--- a/system_server.te
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+++ b/system_server.te
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@@ -107,6 +107,9 @@ allow system_server proc_uid_cputime_removeuid:file { w_file_perms getattr };
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# Write to /proc/sysrq-trigger.
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allow system_server proc_sysrq:file rw_file_perms;
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+# Read /proc/stat for CPU usage statistics
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+allow system_server proc_stat:file r_file_perms;
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+
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# Read /sys/kernel/debug/wakeup_sources.
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allow system_server debugfs:file r_file_perms;
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