commit e4fde8aefeeee52d52d60fb2db6d0844837a323c
author Jorge Lucangeli Obes <jorgelo@google.com> Mon Jul 18 16:09:29 2016 +0000
committer android-build-merger <android-build-merger@google.com> Mon Jul 18 16:09:29 2016 +0000
tree 45762512270df2a92bab6ee432dd3710eccd0b7b
parent 92cf91e1a0adb67c42a6d5873174a52dd7d5f595
parent 6df3365707b19175a503b49d653a32c86378c969

Merge \\"Use Minijail for privilege dropping.\\" am: 97f49e5cb3
am: fe4f764e75

Change-Id: I878d09de7ec1063121a2b3868c43d7fd5b026f9e

sdcard/Android.mk

diff --git a/sdcard/Android.mk b/sdcard/Android.mk
index f87e2d5..992b51c 100644
--- a/sdcard/Android.mk
+++ b/sdcard/Android.mk
@@ -5,7 +5,7 @@
 LOCAL_SRC_FILES := sdcard.cpp fuse.cpp
 LOCAL_MODULE := sdcard
 LOCAL_CFLAGS := -Wall -Wno-unused-parameter -Werror
-LOCAL_SHARED_LIBRARIES := libbase liblog libcutils libpackagelistparser
+LOCAL_SHARED_LIBRARIES := libbase liblog libcutils libminijail libpackagelistparser
 
 LOCAL_SANITIZE := integer
 LOCAL_CLANG := true

sdcard/sdcard.cpp

diff --git a/sdcard/sdcard.cpp b/sdcard/sdcard.cpp
index dd0c433..e82f29e 100644
--- a/sdcard/sdcard.cpp
+++ b/sdcard/sdcard.cpp
@@ -36,6 +36,9 @@
 #include <cutils/multiuser.h>
 #include <packagelistparser/packagelistparser.h>
 
+#include <libminijail.h>
+#include <scoped_minijail.h>
+
 #include <private/android_filesystem_config.h>
 
 // README
@@ -204,6 +207,15 @@
     return 0;
 }
 
+static void drop_privs(uid_t uid, gid_t gid) {
+    ScopedMinijail j(minijail_new());
+    minijail_set_supplementary_gids(j.get(), sizeof(kGroups) / sizeof(kGroups[0]), kGroups);
+    minijail_change_gid(j.get(), gid);
+    minijail_change_uid(j.get(), uid);
+    /* minijail_enter() will abort if priv-dropping fails. */
+    minijail_enter(j.get());
+}
+
 static void* start_handler(void* data) {
     struct fuse_handler* handler = static_cast<fuse_handler*>(data);
     handle_fuse_requests(handler);
@@ -299,16 +311,8 @@
         }
     }
 
-    /* Drop privs. */
-    if (setgroups(sizeof(kGroups) / sizeof(kGroups[0]), kGroups) < 0) {
-        PLOG(FATAL) << "cannot setgroups";
-    }
-    if (setgid(gid) < 0) {
-        PLOG(FATAL) << "cannot setgid";
-    }
-    if (setuid(uid) < 0) {
-        PLOG(FATAL) << "cannot setuid";
-    }
+    // Will abort if priv-dropping fails.
+    drop_privs(uid, gid);
 
     if (multi_user) {
         fs_prepare_dir(global.obb_path, 0775, uid, gid);