commit ccf343fa5b51fb0b695ff7444111971d458eeefe
author Kalesh Singh <kaleshsingh@google.com> Mon Dec 06 16:13:06 2021 -0800
committer Kalesh Singh <kaleshsingh@google.com> Mon Dec 06 16:25:04 2021 -0800
tree 3cb946205e5575c104ff0004494e9e97b4d4b1bf
parent f7da22dfe5849db5ee51f9bf05b8825ea2cde2f9

Add group ID for reading tracefs

Add AID_READTRACEFS and mount tracefs with gid=AID_READTRACEFS

Bug: 209513178
Test: adb shell ls -l /sys/kernel/tracing/events
Change-Id: Ibbfdf8a4b771bd7520ecbaaf15a1153d6bf0e599

libcutils/include/private/android_filesystem_config.h

diff --git a/libcutils/include/private/android_filesystem_config.h b/libcutils/include/private/android_filesystem_config.h
index e65fe92..9b5d052 100644
--- a/libcutils/include/private/android_filesystem_config.h
+++ b/libcutils/include/private/android_filesystem_config.h
@@ -158,6 +158,7 @@
 #define AID_READPROC 3009     /* Allow /proc read access */
 #define AID_WAKELOCK 3010     /* Allow system wakelock read/write access */
 #define AID_UHID 3011         /* Allow read/write to /dev/uhid node */
+#define AID_READTRACEFS 3012  /* Allow tracefs read */
 
 /* The range 5000-5999 is also reserved for vendor partition. */
 #define AID_OEM_RESERVED_2_START 5000

rootdir/init.rc

diff --git a/rootdir/init.rc b/rootdir/init.rc
index b09c2f1..42545d9 100644
--- a/rootdir/init.rc
+++ b/rootdir/init.rc
@@ -78,8 +78,8 @@
     mkdir /dev/boringssl 0755 root root
     mkdir /dev/boringssl/selftest 0755 root root
 
-    # Mount tracefs
-    mount tracefs tracefs /sys/kernel/tracing
+    # Mount tracefs (with GID=AID_READTRACEFS)
+    mount tracefs tracefs /sys/kernel/tracing gid=3012
 
     # create sys dirctory
     mkdir /dev/sys 0755 system system