logd: Use Minijail for privilege dropping.
Makes code smaller, removes duplication. Using Minijail also allows
adding further sandboxing down the road.
Bug: 30156807
Change-Id: I8fa242fba545049ee82f6655fe6ecc14c53fcab7
diff --git a/logd/Android.mk b/logd/Android.mk
index 84ea7a2..3348890 100644
--- a/logd/Android.mk
+++ b/logd/Android.mk
@@ -28,7 +28,8 @@
liblog \
libcutils \
libbase \
- libpackagelistparser
+ libpackagelistparser \
+ libminijail
# This is what we want to do:
# event_logtags = $(shell \
diff --git a/logd/main.cpp b/logd/main.cpp
index 69ba896..b69927d 100644
--- a/logd/main.cpp
+++ b/logd/main.cpp
@@ -36,12 +36,15 @@
#include <cstdbool>
#include <memory>
+#include <android-base/macros.h>
#include <cutils/properties.h>
#include <cutils/sched_policy.h>
#include <cutils/sockets.h>
+#include <libminijail.h>
#include <log/event_tag_map.h>
#include <packagelistparser/packagelistparser.h>
#include <private/android_filesystem_config.h>
+#include <scoped_minijail.h>
#include <utils/threads.h>
#include "CommandListener.h"
@@ -58,14 +61,14 @@
'>'
//
-// The service is designed to be run by init, it does not respond well
+// The service is designed to be run by init, it does not respond well
// to starting up manually. When starting up manually the sockets will
// fail to open typically for one of the following reasons:
// EADDRINUSE if logger is running.
// EACCESS if started without precautions (below)
//
// Here is a cookbook procedure for starting up logd manually assuming
-// init is out of the way, pedantically all permissions and selinux
+// init is out of the way, pedantically all permissions and SELinux
// security is put back in place:
//
// setenforce 0
@@ -102,43 +105,13 @@
return -1;
}
- if (prctl(PR_SET_KEEPCAPS, 1) < 0) {
- return -1;
- }
-
gid_t groups[] = { AID_READPROC };
-
- if (setgroups(sizeof(groups) / sizeof(groups[0]), groups) == -1) {
- return -1;
- }
-
- if (setgid(AID_LOGD) != 0) {
- return -1;
- }
-
- if (setuid(AID_LOGD) != 0) {
- return -1;
- }
-
- struct __user_cap_header_struct capheader;
- struct __user_cap_data_struct capdata[2];
- memset(&capheader, 0, sizeof(capheader));
- memset(&capdata, 0, sizeof(capdata));
- capheader.version = _LINUX_CAPABILITY_VERSION_3;
- capheader.pid = 0;
-
- capdata[CAP_TO_INDEX(CAP_SYSLOG)].permitted = CAP_TO_MASK(CAP_SYSLOG);
- capdata[CAP_TO_INDEX(CAP_AUDIT_CONTROL)].permitted |= CAP_TO_MASK(CAP_AUDIT_CONTROL);
-
- capdata[0].effective = capdata[0].permitted;
- capdata[1].effective = capdata[1].permitted;
- capdata[0].inheritable = 0;
- capdata[1].inheritable = 0;
-
- if (capset(&capheader, &capdata[0]) < 0) {
- return -1;
- }
-
+ ScopedMinijail j(minijail_new());
+ minijail_set_supplementary_gids(j.get(), arraysize(groups), groups);
+ minijail_change_uid(j.get(), AID_LOGD);
+ minijail_change_gid(j.get(), AID_LOGD);
+ minijail_use_caps(j.get(), CAP_TO_MASK(CAP_SYSLOG) | CAP_TO_MASK(CAP_AUDIT_CONTROL));
+ minijail_enter(j.get());
return 0;
}