From c12c734932a3359ee6ae98859c40b355b151dc8d Mon Sep 17 00:00:00 2001
From: Steven Moreland <smoreland@google.com>
Date: Wed, 30 Aug 2017 13:30:13 -0700
Subject: [PATCH] Permissions for screencap saving files to /sdcard/
Before screencap was in its own domain, it was able to do
this by using all of shell's permissions.
The following denials are caused (along with times from running the below test command)
when screencap is invoked to write a file onto the sdcard:
08-30 21:03:32.009 4986 4986 I screencap: type=1400 audit(0.0:23): avc: denied { read } for name="primary" dev="tmpfs" ino=19547 scontext=u:r:screencap:s0 tcontext=u:object_r:storage_file:s0 tclass=lnk_file permissive=1
08-30 21:03:32.009 4986 4986 I screencap: type=1400 audit(0.0:24): avc: denied { search } for name="/" dev="tmpfs" ino=19529 scontext=u:r:screencap:s0 tcontext=u:object_r:tmpfs:s0 tclass=dir permissive=1
08-30 21:03:32.009 4986 4986 I screencap: type=1400 audit(0.0:25): avc: denied { search } for name="user" dev="tmpfs" ino=19535 scontext=u:r:screencap:s0 tcontext=u:object_r:mnt_user_file:s0 tclass=dir permissive=1
08-30 21:03:32.009 4986 4986 I screencap: type=1400 audit(0.0:26): avc: denied { read } for name="primary" dev="tmpfs" ino=31198 scontext=u:r:screencap:s0 tcontext=u:object_r:mnt_user_file:s0 tclass=lnk_file permissive=1
08-30 21:03:32.009 4986 4986 I screencap: type=1400 audit(0.0:27): avc: denied { search } for name="/" dev="sdcardfs" ino=1310722 scontext=u:r:screencap:s0 tcontext=u:object_r:sdcardfs:s0 tclass=dir permissive=1
08-30 21:03:32.009 4986 4986 I screencap: type=1400 audit(0.0:28): avc: denied { write } for name="image.png" dev="sdcardfs" ino=1310764 scontext=u:r:screencap:s0 tcontext=u:object_r:sdcardfs:s0 tclass=file permissive=1
08-30 21:03:32.009 4986 4986 I screencap: type=1400 audit(0.0:29): avc: denied { open } for path="/storage/emulated/0/image.png" dev="sdcardfs" ino=1310764 scontext=u:r:screencap:s0 tcontext=u:object_r:sdcardfs:s0 tclass=file permissive=1
08-30 21:03:32.009 4986 4986 I screencap: type=1400 audit(0.0:30): avc: denied { write open } for path="/data/media/0/image.png" dev="sda45" ino=1310764 scontext=u:r:screencap:s0 tcontext=u:object_r:media_rw_data_file:s0 tclass=file permissive=1
08-30 21:03:32.582 4990 4990 I screencap: type=1400 audit(0.0:31): avc: denied { execute } for name="sh" dev="dm-0" ino=998 scontext=u:r:screencap:s0 tcontext=u:object_r:shell_exec:s0 tclass=file permissive=1
08-30 21:03:32.582 4990 4990 I screencap: type=1400 audit(0.0:32): avc: denied { read open } for path="/system/bin/sh" dev="dm-0" ino=998 scontext=u:r:screencap:s0 tcontext=u:object_r:shell_exec:s0 tclass=file permissive=1
08-30 21:03:32.582 4990 4990 I screencap: type=1400 audit(0.0:33): avc: denied { execute_no_trans } for path="/system/bin/sh" dev="dm-0" ino=998 scontext=u:r:screencap:s0 tcontext=u:object_r:shell_exec:s0 tclass=file permissive=1
08-30 21:03:32.582 4990 4990 I sh : type=1400 audit(0.0:34): avc: denied { getattr } for path="/system/bin/sh" dev="dm-0" ino=998 scontext=u:r:screencap:s0 tcontext=u:object_r:shell_exec:s0 tclass=file permissive=1
08-30 21:03:32.586 4990 4990 I sh : type=1400 audit(0.0:35): avc: denied { ioctl } for path="socket:[57515]" dev="sockfs" ino=57515 ioctlcmd=5401 scontext=u:r:screencap:s0 tcontext=u:r:adbd:s0 tclass=unix_stream_socket permissive=1
08-30 21:03:32.586 4990 4990 I sh : type=1400 audit(0.0:36): avc: denied { getattr } for path="socket:[57515]" dev="sockfs" ino=57515 scontext=u:r:screencap:s0 tcontext=u:r:adbd:s0 tclass=unix_stream_socket permissive=1
08-30 21:03:32.589 4991 4991 I sh : type=1400 audit(0.0:37): avc: denied { execute_no_trans } for path="/system/bin/am" dev="dm-0" ino=1178 scontext=u:r:screencap:s0 tcontext=u:object_r:system_file:s0 tclass=file permissive=1
08-30 21:03:32.739 4992 4992 I cmd : type=1400 audit(0.0:38): avc: denied { call } for scontext=u:r:screencap:s0 tcontext=u:r:system_server:s0 tclass=binder permissive=1
08-30 21:03:32.739 4992 4992 I cmd : type=1400 audit(0.0:39): avc: denied { use } for path="/dev/null" dev="tmpfs" ino=19514 scontext=u:r:system_server:s0 tcontext=u:r:screencap:s0 tclass=fd permissive=1
08-30 21:03:32.739 4992 4992 I cmd : type=1400 audit(0.0:40): avc: denied { transfer } for scontext=u:r:screencap:s0 tcontext=u:r:system_server:s0 tclass=binder permissive=1
08-30 21:03:32.741 575 575 E SELinux : avc: denied { find } for service=activity pid=4992 uid=2000 scontext=u:r:screencap:s0 tcontext=u:object_r:activity_service:s0 tclass=service_manager permissive=1
08-30 21:03:32.749 837 837 I Binder:837_9: type=1400 audit(0.0:41): avc: denied { call } for scontext=u:r:system_server:s0 tcontext=u:r:screencap:s0 tclass=binder permissive=1
If /data/media/ is deleted, the following denials also occur:
08-31 00:45:45.966 8899 8899 I screencap: type=1400 audit(0.0:43): avc: denied { search } for name="0" dev="sda45" ino=1310728 scontext=u:r:screencap:s0 tcontext=u:object_r:media_rw_data_file:s0 tclass=dir permissive=1
08-31 00:45:45.966 8899 8899 I screencap: type=1400 audit(0.0:44): avc: denied { read open } for path="/data/media/0" dev="sda45" ino=1310728 scontext=u:r:screencap:s0 tcontext=u:object_r:media_rw_data_file:s0 tclass=dir permissive=1
08-31 00:45:45.966 8899 8899 I screencap: type=1400 audit(0.0:48): avc: denied { write } for name="0" dev="sda45" ino=1310728 scontext=u:r:screencap:s0 tcontext=u:object_r:media_rw_data_file:s0 tclass=dir permissive=1
08-31 00:45:45.966 8899 8899 I screencap: type=1400 audit(0.0:49): avc: denied { add_name } for name="image.png" scontext=u:r:screencap:s0 tcontext=u:object_r:media_rw_data_file:s0 tclass=dir permissive=1
08-31 00:45:45.966 8899 8899 I screencap: type=1400 audit(0.0:50): avc: denied { create } for name="image.png" scontext=u:r:screencap:s0 tcontext=u:object_r:media_rw_data_file:s0 tclass=file permissive=1
08-31 00:45:45.966 8899 8899 I screencap: type=1400 audit(0.0:51): avc: denied { setattr } for name="image.png" dev="sda45" ino=1310764 scontext=u:r:screencap:s0 tcontext=u:object_r:media_rw_data_file:s0 tclass=file permissive=1
08-31 00:45:45.966 8899 8899 I screencap: type=1400 audit(0.0:53): avc: denied { write open } for path="/data/media/0/image.png" dev="sda45" ino=1310764 scontext=u:r:screencap:s0 tcontext=u:object_r:media_rw_data_file:s0 tclass=file permissive=1
08-31 01:04:29.741 6625 6625 W screencap: type=1400 audit(0.0:23): avc: denied { write } for name="0" dev="sdcardfs" ino=655364 scontext=u:r:screencap:s0 tcontext=u:object_r:sdcardfs:s0 tclass=dir permissive=0
Test: adb shell screencap -p /sdcard/phone.png
Bug: 65206688
Change-Id: I808429b25fa3118fef7931050ab757c9bcd61881
---
private/screencap.te | 18 ++++++++++++++++--
private/system_server.te | 1 +
2 files changed, 17 insertions(+), 2 deletions(-)
diff --git a/private/screencap.te b/private/screencap.te
index 579373aa6..764880f55 100644
--- a/private/screencap.te
+++ b/private/screencap.te
@@ -8,7 +8,7 @@ allow screencap ion_device:chr_file rw_file_perms;
allow screencap adbd:fifo_file write;
allow screencap adbd:fd use;
-allow screencap adbd:unix_stream_socket { read write };
+allow screencap adbd:unix_stream_socket { read write getattr ioctl };
allow screencap shell_data_file:file write;
allow screencap shell:fd use;
@@ -20,7 +20,21 @@ allow screencap dumpstate:unix_stream_socket { read write };
binder_use(screencap)
binder_call(screencap, surfaceflinger)
allow screencap surfaceflinger_service:service_manager find;
-allow screencap surfaceflinger:fd use;
+binder_call(screencap, system_server)
+allow screencap activity_service:service_manager find;
hwbinder_use(screencap)
hal_client_domain(screencap, hal_graphics_allocator)
+
+allow screencap shell_exec:file rx_file_perms;
+allow screencap system_file:file execute_no_trans;
+
+allow screencap media_rw_data_file:dir rw_dir_perms;
+allow screencap media_rw_data_file:file rw_file_perms;
+allow screencap mnt_user_file:dir search;
+allow screencap mnt_user_file:lnk_file read;
+allow screencap sdcardfs:dir { search write };
+allow screencap sdcardfs:file { open write };
+allow screencap storage_file:dir search;
+allow screencap storage_file:lnk_file read;
+allow screencap tmpfs:dir search;
diff --git a/private/system_server.te b/private/system_server.te
index a46272ad6..00dc6a568 100644
--- a/private/system_server.te
+++ b/private/system_server.te
@@ -181,6 +181,7 @@ binder_call(system_server, gatekeeperd)
binder_call(system_server, installd)
binder_call(system_server, incidentd)
binder_call(system_server, netd)
+binder_call(system_server, screencap)
binder_call(system_server, wificond)
binder_service(system_server)
--
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