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Commit 01272d0e authored by Inseob Kim's avatar Inseob Kim
Browse files

Add hidden API to get vendor genfs version 

As genfs_contexts depends on vendors, users should be able to read the
genfs versions of vendors to implement fallback mechanism for new
features. This adds a new hidden API reading the version.

To prevent from diverging, the hidden API uses native libraries
(libgenfslabelsversion).

Bug: 378805380
Test: create a bundled app, call SELinux.getGenfsLabelsVersion
Change-Id: I8993f8dca9a7e9e6aff835e94ba6e5bc87612e1d
parent 0222489d

core/java/android/os/SELinux.java

+27 −0
Original line number Diff line number Diff line
@@ -193,4 +193,31 @@ public class SELinux { 
            return false;

        }

    }



    /**

     * Gets the genfs labels version of the vendor. The genfs labels version is

     * specified in {@code /vendor/etc/selinux/genfs_labels_version.txt}. The

     * version follows the VINTF version format "YYYYMM" and affects how {@code

     * genfs_contexts} entries are applied.

     *

     * <p>The genfs labels version indicates changes in the SELinux labeling

     * scheme over time. For example:

     * <ul>

     *   <li>For version 202504 and later, {@code /sys/class/udc} is labeled as

     *   {@code sysfs_udc}.

     *   <li>For version 202404 and earlier, {@code /sys/class/udc} is labeled

     *   as {@code sysfs}.

     * </ul>

     * Check {@code /system/etc/selinux/plat_sepolicy_genfs_{version}.cil} to

     * see which labels are new in {version}.

     *

     * <p>Older vendors may override {@code genfs_contexts} with vendor-specific

     * extensions. The framework must not break such labellings to maintain

     * compatibility with such vendors, by checking the genfs labels version and

     * implementing a fallback mechanism.

     *

     * @return an integer representing the genfs labels version of /vendor, in

     *         the format YYYYMM.

     */

    public static final native int getGenfsLabelsVersion();

}

core/jni/Android.bp

+1 −0
Original line number Diff line number Diff line
@@ -287,6 +287,7 @@ cc_library_shared_for_libandroid_runtime { 
                "libasync_safe",

                "libbinderthreadstateutils",

                "libdmabufinfo",

                "libgenfslabelsversion.ffi",

                "libgui_window_info_static",

                "libkernelconfigs",

                "libnativehelper_lazy",

core/jni/android_os_SELinux.cpp

+22 −8
Original line number Diff line number Diff line
@@ -18,18 +18,19 @@ 


#include <errno.h>

#include <fcntl.h>



#include <genfslabelsversion.h>

#include <nativehelper/JNIPlatformHelp.h>

#include <nativehelper/ScopedLocalRef.h>

#include <nativehelper/ScopedUtfChars.h>

#include <utils/Log.h>



#include <nativehelper/JNIPlatformHelp.h>

#include "jni.h"

#include <atomic>

#include <memory>



#include "core_jni_helpers.h"

#include "selinux/selinux.h"

#include "jni.h"

#include "selinux/android.h"

#include <memory>

#include <atomic>

#include <nativehelper/ScopedLocalRef.h>

#include <nativehelper/ScopedUtfChars.h>

#include "selinux/selinux.h"



namespace android {

namespace {
@@ -403,9 +404,20 @@ static jboolean native_restorecon(JNIEnv *env, jobject, jstring pathnameStr, jin 
    return (ret == 0);

}



/*

 * Function: getGenfsLabelsVersion

 * Purpose: get which genfs labels version /vendor uses

 * Returns: int: genfs labels version of /vendor

 * Exceptions: none

 */

static jint getGenfsLabelsVersion(JNIEnv *, jclass) {

    return get_genfs_labels_version();

}



/*

 * JNI registration.

 */

// clang-format off

static const JNINativeMethod method_table[] = {

    /* name,                     signature,                    funcPtr */

    { "checkSELinuxAccess"       , "(Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;)Z" , (void*)checkSELinuxAccess },
@@ -420,7 +432,9 @@ static const JNINativeMethod method_table[] = { 
    { "setFileContext"           , "(Ljava/lang/String;Ljava/lang/String;)Z"      , (void*)setFileCon       },

    { "setFSCreateContext"       , "(Ljava/lang/String;)Z"                        , (void*)setFSCreateCon   },

    { "fileSelabelLookup"        , "(Ljava/lang/String;)Ljava/lang/String;"       , (void*)fileSelabelLookup},

    { "getGenfsLabelsVersion"    , "()I"                                          , (void *)getGenfsLabelsVersion},

};

// clang-format on



static int log_callback(int type, const char *fmt, ...) {

    va_list ap;