init: split security functions out of init.cpp

This change splits out the selinux initialization and supporting
functionality into selinux.cpp and splits the security related
initialization of the rng, etc to security.cpp.  It also provides
additional documentation for SEPolicy loading as this has been
requested by some teams.

It additionally cleans up sehandle and sehandle_prop.  The former is
static within selinux.cpp and new wrapper functions are created around
selabel_lookup*() to better serve the users.  The latter is moved to
property_service.cpp as it is isolated to that file for its usage.

Test: boot bullhead
Merged-In: Idc95d493cebc681fbe686b5160502f36af149f60
Change-Id: Idc95d493cebc681fbe686b5160502f36af149f60
diff --git a/init/util.cpp b/init/util.cpp
index fdcb22d..e037987 100644
--- a/init/util.cpp
+++ b/init/util.cpp
@@ -42,6 +42,7 @@
 #include <selinux/android.h>
 
 #include "reboot.h"
+#include "selinux.h"
 
 #ifdef _INIT_INIT_H
 #error "Do not include init.h in files used by ueventd or watchdogd; it will expose init's globals"
@@ -89,7 +90,7 @@
  * variable ANDROID_SOCKET_ENV_PREFIX<name> ("ANDROID_SOCKET_foo").
  */
 int CreateSocket(const char* name, int type, bool passcred, mode_t perm, uid_t uid, gid_t gid,
-                 const char* socketcon, selabel_handle* sehandle) {
+                 const char* socketcon) {
     if (socketcon) {
         if (setsockcreatecon(socketcon) == -1) {
             PLOG(ERROR) << "setsockcreatecon(\"" << socketcon << "\") failed";
@@ -116,11 +117,9 @@
         return -1;
     }
 
-    char *filecon = NULL;
-    if (sehandle) {
-        if (selabel_lookup(sehandle, &filecon, addr.sun_path, S_IFSOCK) == 0) {
-            setfscreatecon(filecon);
-        }
+    std::string secontext;
+    if (SelabelLookupFileContext(addr.sun_path, S_IFSOCK, &secontext) && !secontext.empty()) {
+        setfscreatecon(secontext.c_str());
     }
 
     if (passcred) {
@@ -134,8 +133,9 @@
     int ret = bind(fd, (struct sockaddr *) &addr, sizeof (addr));
     int savederrno = errno;
 
-    setfscreatecon(NULL);
-    freecon(filecon);
+    if (!secontext.empty()) {
+        setfscreatecon(nullptr);
+    }
 
     if (ret) {
         errno = savederrno;
@@ -210,19 +210,19 @@
     return true;
 }
 
-int mkdir_recursive(const std::string& path, mode_t mode, selabel_handle* sehandle) {
+bool mkdir_recursive(const std::string& path, mode_t mode) {
     std::string::size_type slash = 0;
     while ((slash = path.find('/', slash + 1)) != std::string::npos) {
         auto directory = path.substr(0, slash);
         struct stat info;
         if (stat(directory.c_str(), &info) != 0) {
-            auto ret = make_dir(directory.c_str(), mode, sehandle);
-            if (ret && errno != EEXIST) return ret;
+            auto ret = make_dir(directory, mode);
+            if (!ret && errno != EEXIST) return false;
         }
     }
-    auto ret = make_dir(path.c_str(), mode, sehandle);
-    if (ret && errno != EEXIST) return ret;
-    return 0;
+    auto ret = make_dir(path, mode);
+    if (!ret && errno != EEXIST) return false;
+    return true;
 }
 
 int wait_for_file(const char* filename, std::chrono::nanoseconds timeout) {
@@ -249,26 +249,21 @@
     }
 }
 
-int make_dir(const char* path, mode_t mode, selabel_handle* sehandle) {
-    int rc;
-
-    char *secontext = NULL;
-
-    if (sehandle) {
-        selabel_lookup(sehandle, &secontext, path, mode);
-        setfscreatecon(secontext);
+bool make_dir(const std::string& path, mode_t mode) {
+    std::string secontext;
+    if (SelabelLookupFileContext(path, mode, &secontext) && !secontext.empty()) {
+        setfscreatecon(secontext.c_str());
     }
 
-    rc = mkdir(path, mode);
+    int rc = mkdir(path.c_str(), mode);
 
-    if (secontext) {
+    if (!secontext.empty()) {
         int save_errno = errno;
-        freecon(secontext);
-        setfscreatecon(NULL);
+        setfscreatecon(nullptr);
         errno = save_errno;
     }
 
-    return rc;
+    return rc == 0;
 }
 
 /*