8277489: Rewrite JAAS UnixLoginModule with FFM

Co-authored-by: Martin Doerr <mdoerr@openjdk.org>
Reviewed-by: mdoerr, ascarpino, erikj

make/modules/jdk.security.auth/Lib.gmk

@@ -31,13 +31,14 @@ include LibCommon.gmk
 ## Build libjaas
 ################################################################################
 
-$(eval $(call SetupJdkLibrary, BUILD_LIBJAAS, \
+ifeq ($(call isTargetOs, windows), true)
-    NAME := jaas, \
+  $(eval $(call SetupJdkLibrary, BUILD_LIBJAAS, \
-    OPTIMIZATION := LOW, \
+      NAME := jaas, \
-    EXTRA_HEADER_DIRS := java.base:libjava, \
+      OPTIMIZATION := LOW, \
-    LIBS_windows := advapi32.lib mpr.lib netapi32.lib user32.lib, \
+      EXTRA_HEADER_DIRS := java.base:libjava, \
-))
+      LIBS_windows := advapi32.lib mpr.lib netapi32.lib user32.lib, \
-
+  ))
-TARGETS += $(BUILD_LIBJAAS)
 
+  TARGETS += $(BUILD_LIBJAAS)
+endif
 ################################################################################

src/java.base/share/classes/module-info.java

@@ -274,7 +274,8 @@ module java.base {
         jdk.httpserver,
         jdk.jlink,
         jdk.jpackage,
-        jdk.net;
+        jdk.net,
+        jdk.security.auth;
     exports sun.net to
         java.net.http,
         jdk.naming.dns;

src/jdk.security.auth/share/classes/com/sun/security/auth/module/UnixLoginModule.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000, 2024, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 2026, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -26,7 +26,6 @@
 package com.sun.security.auth.module;
 
 import java.util.*;
-import java.io.IOException;
 import javax.security.auth.*;
 import javax.security.auth.callback.*;
 import javax.security.auth.login.*;
@@ -34,6 +33,7 @@ import javax.security.auth.spi.*;
 import com.sun.security.auth.UnixPrincipal;
 import com.sun.security.auth.UnixNumericUserPrincipal;
 import com.sun.security.auth.UnixNumericGroupPrincipal;
+import jdk.internal.util.OperatingSystem;
 
 /**
  * This {@code LoginModule} imports a user's Unix
@@ -121,20 +121,34 @@ public class UnixLoginModule implements LoginModule {
      */
     public boolean login() throws LoginException {
 
-        long[] unixGroups = null;
+        // Fail immediately on Windows to avoid cygwin-like functions
+        // being loaded, which are not supported.
+        if (OperatingSystem.isWindows()) {
+            throw new FailedLoginException
+                    ("Failed in attempt to import " +
+                            "the underlying system identity information" +
+                            " on " + System.getProperty("os.name"));
+        }
 
         try {
             ss = new UnixSystem();
-        } catch (UnsatisfiedLinkError ule) {
+        } catch (ExceptionInInitializerError | UnsatisfiedLinkError ule) {
+            // Errors could happen in either static blocks or the constructor,
+            // both have a cause.
             succeeded = false;
-            throw new FailedLoginException
+            var error = new FailedLoginException
                                 ("Failed in attempt to import " +
                                 "the underlying system identity information" +
                                 " on " + System.getProperty("os.name"));
+            if (ule.getCause() != null) {
+                error.initCause(ule.getCause());
+            }
+            throw error;
         }
         userPrincipal = new UnixPrincipal(ss.getUsername());
         UIDPrincipal = new UnixNumericUserPrincipal(ss.getUid());
         GIDPrincipal = new UnixNumericGroupPrincipal(ss.getGid(), true);
+        long[] unixGroups = null;
         if (ss.getGroups() != null && ss.getGroups().length > 0) {
             unixGroups = ss.getGroups();
             for (int i = 0; i < unixGroups.length; i++) {
@@ -150,9 +164,11 @@ public class UnixLoginModule implements LoginModule {
                     "succeeded importing info: ");
             System.out.println("\t\t\tuid = " + ss.getUid());
             System.out.println("\t\t\tgid = " + ss.getGid());
-            unixGroups = ss.getGroups();
+            System.out.println("\t\t\tusername = " + ss.getUsername());
-            for (int i = 0; i < unixGroups.length; i++) {
+            if (unixGroups != null) {
-                System.out.println("\t\t\tsupp gid = " + unixGroups[i]);
+                for (int i = 0; i < unixGroups.length; i++) {
+                    System.out.println("\t\t\tsupp gid = " + unixGroups[i]);
+                }
             }
         }
         succeeded = true;

src/jdk.security.auth/share/classes/com/sun/security/auth/module/UnixSystem.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000, 2024, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 2026, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -25,38 +25,194 @@
 
 package com.sun.security.auth.module;
 
+import jdk.internal.util.Architecture;
+import jdk.internal.util.OperatingSystem;
+
+import java.lang.foreign.AddressLayout;
+import java.lang.foreign.Arena;
+import java.lang.foreign.FunctionDescriptor;
+import java.lang.foreign.GroupLayout;
+import java.lang.foreign.Linker;
+import java.lang.foreign.MemoryLayout;
+import java.lang.foreign.MemorySegment;
+import java.lang.foreign.StructLayout;
+import java.lang.foreign.SymbolLookup;
+import java.lang.foreign.ValueLayout;
+import java.lang.invoke.MethodHandle;
+import java.lang.invoke.VarHandle;
+
+import static java.lang.foreign.MemoryLayout.PathElement.groupElement;
+
 /**
  * This class implementation retrieves and makes available Unix
  * UID/GID/groups information for the current user.
  *
  * @since 1.4
  */
+@SuppressWarnings("restricted")
 public class UnixSystem {
 
-    private native void getUnixInfo();
+    /**
-
+     * The current username.
-    // Warning: the following 4 fields are used by Unix.c
+     */
-
-    /** The current username. */
     protected String username;
 
-    /** The current user ID. */
+    /**
+     * The current user ID.
+     */
     protected long uid;
 
-    /** The current group ID. */
+    /**
+     * The current group ID.
+     */
     protected long gid;
 
-    /** The current list of groups. */
+    /**
+     * The current list of groups.
+     */
     protected long[] groups;
 
+    private static final Linker LINKER = Linker.nativeLinker();
+    private static final SymbolLookup SYMBOL_LOOKUP = SymbolLookup.loaderLookup()
+            .or(LINKER.defaultLookup());
+
+    private static final ValueLayout.OfByte C_CHAR
+            = (ValueLayout.OfByte) LINKER.canonicalLayouts().get("char");
+    private static final ValueLayout.OfInt C_INT
+            = (ValueLayout.OfInt) LINKER.canonicalLayouts().get("int");
+    private static final ValueLayout.OfLong C_LONG
+            = (ValueLayout.OfLong) LINKER.canonicalLayouts().get("long");
+    private static final AddressLayout C_POINTER
+            = ((AddressLayout) LINKER.canonicalLayouts().get("void*"))
+            .withTargetLayout(MemoryLayout.sequenceLayout(java.lang.Long.MAX_VALUE, C_CHAR));
+    private static final ValueLayout C_SIZE_T
+            = (ValueLayout) LINKER.canonicalLayouts().get("size_t");
+
+    private static final StructLayout CAPTURE_STATE_LAYOUT
+            = Linker.Option.captureStateLayout();
+    private static final VarHandle VH_errno = CAPTURE_STATE_LAYOUT.varHandle(
+            MemoryLayout.PathElement.groupElement("errno"));
+
+    private static final MethodHandle MH_strerror
+            = LINKER.downcallHandle(SYMBOL_LOOKUP.findOrThrow("strerror"),
+                    FunctionDescriptor.of(C_POINTER, C_INT));
+
+    private static final MethodHandle MH_getgroups
+            = LINKER.downcallHandle(SYMBOL_LOOKUP.findOrThrow("getgroups"),
+                    FunctionDescriptor.of(C_INT, C_INT, C_POINTER),
+                    Linker.Option.captureCallState("errno"));
+    private static final MethodHandle MH_getuid
+            = LINKER.downcallHandle(SYMBOL_LOOKUP.findOrThrow("getuid"),
+                    FunctionDescriptor.of(C_INT));
+
+    // Some architectures require appropriate zero or sign extension to 64 bit.
+    // Use long directly before https://bugs.openjdk.org/browse/JDK-8336664 is resolved.
+    private static final boolean calling_convention_requires_int_as_long
+            = Architecture.isPPC64() || Architecture.isPPC64LE() || Architecture.isS390();
+
+    // getpwuid_r does not work on AIX, instead we use another similar function
+    // extern int _posix_getpwuid_r(uid_t, struct passwd *, char *, int, struct passwd **)
+    private static final MethodHandle MH_getpwuid_r
+            = LINKER.downcallHandle(SYMBOL_LOOKUP.findOrThrow(
+                            OperatingSystem.isAix() ? "_posix_getpwuid_r" : "getpwuid_r"),
+                    FunctionDescriptor.of(C_INT,
+                            calling_convention_requires_int_as_long ? C_LONG : C_INT,
+                            C_POINTER, C_POINTER,
+                            OperatingSystem.isAix() ? C_INT : C_SIZE_T,
+                            C_POINTER));
+
+    private static final GroupLayout ML_passwd = MemoryLayout.structLayout(
+            C_POINTER.withName("pw_name"),
+            C_POINTER.withName("pw_passwd"),
+            C_INT.withName("pw_uid"),
+            C_INT.withName("pw_gid"),
+            // Different platforms have different fields in `struct passwd`.
+            // While we don't need those fields here, the struct needs to be
+            // big enough to avoid buffer overflow when `getpwuid_r` is called.
+            MemoryLayout.paddingLayout(100));
+
+    private static final VarHandle VH_pw_uid
+            = ML_passwd.varHandle(groupElement("pw_uid"));
+    private static final VarHandle VH_pw_gid
+            = ML_passwd.varHandle(groupElement("pw_gid"));
+    private static final VarHandle VH_pw_name
+            = ML_passwd.varHandle(groupElement("pw_name"));
+
+    // The buffer size for the getpwuid_r function:
+    // 1. sysconf(_SC_GETPW_R_SIZE_MAX) on macOS is 4096 and 1024 on Linux,
+    //    so we choose a bigger one.
+    // 2. We do not call sysconf() here because even _SC_GETPW_R_SIZE_MAX
+    //    could be different on different platforms.
+    // 3. We choose int instead of long because the buffer_size argument
+    //    might be `int` or `long` and converting from `long` to `int`
+    //    requires an explicit cast.
+    private static final int GETPW_R_SIZE_MAX = 4096;
+
     /**
      * Instantiate a {@code UnixSystem} and load
      * the native library to access the underlying system information.
      */
-    @SuppressWarnings("restricted")
     public UnixSystem() {
-        System.loadLibrary("jaas");
+        // The FFM code has only been tested on multiple platforms
-        getUnixInfo();
+        // (including macOS, Linux, AIX, etc) and might fail on other
+        // *nix systems. Especially, the `passwd` struct could be defined
+        // differently. I've checked several and an extra 100 chars at the
+        // end seems enough.
+        try (Arena scope = Arena.ofConfined()) {
+            MemorySegment capturedState = scope.allocate(CAPTURE_STATE_LAYOUT);
+            int groupnum = (int) MH_getgroups.invokeExact(capturedState, 0, MemorySegment.NULL);
+            if (groupnum == -1) {
+                throw new RuntimeException("getgroups returns " + groupnum);
+            }
+
+            var gs = scope.allocate(C_INT, groupnum);
+            groupnum = (int) MH_getgroups.invokeExact(capturedState, groupnum, gs);
+            if (groupnum == -1) {
+                var errno = (int) VH_errno.get(capturedState, 0L);
+                var errMsg = (MemorySegment) MH_strerror.invokeExact(errno);
+                throw new RuntimeException("getgroups returns " + groupnum
+                        + ". Reason: " + errMsg.reinterpret(Long.MAX_VALUE).getString(0));
+            }
+
+            groups = new long[groupnum];
+            for (int i = 0; i < groupnum; i++) {
+                groups[i] = Integer.toUnsignedLong(gs.getAtIndex(C_INT, i));
+            }
+
+            var pwd = scope.allocate(ML_passwd);
+            var result = scope.allocate(C_POINTER);
+            var buffer = scope.allocate(GETPW_R_SIZE_MAX);
+
+            long tmpUid = Integer.toUnsignedLong((int) MH_getuid.invokeExact());
+
+            // Do not call invokeExact because the type of buffer_size is not
+            // always long in the underlying system.
+            int out;
+            if (calling_convention_requires_int_as_long) {
+                out = (int) MH_getpwuid_r.invoke(
+                        tmpUid, pwd, buffer, GETPW_R_SIZE_MAX, result);
+            } else {
+                out = (int) MH_getpwuid_r.invoke(
+                        (int) tmpUid, pwd, buffer, GETPW_R_SIZE_MAX, result);
+            }
+            if (out != 0) {
+                // If ERANGE (Result too large) is detected in a new platform,
+                // consider adjusting GETPW_R_SIZE_MAX.
+                var err = (MemorySegment) MH_strerror.invokeExact(out);
+                throw new RuntimeException(err.reinterpret(Long.MAX_VALUE).getString(0));
+            } else if (result.get(ValueLayout.ADDRESS, 0).equals(MemorySegment.NULL)) {
+                throw new RuntimeException("the requested entry is not found");
+            } else {
+                // uid_t and gid_t were defined unsigned.
+                uid = Integer.toUnsignedLong((int) VH_pw_uid.get(pwd, 0L));
+                gid = Integer.toUnsignedLong((int) VH_pw_gid.get(pwd, 0L));
+                username = ((MemorySegment) VH_pw_name.get(pwd, 0L)).getString(0);
+            }
+        } catch (Throwable t) {
+            var error = new UnsatisfiedLinkError("FFM calls failed");
+            error.initCause(t);
+            throw error;
+        }
     }
 
     /**

src/jdk.security.auth/unix/native/libjaas/Unix.c

@@ -1,130 +0,0 @@
-/*
- * Copyright (c) 2000, 2021, Oracle and/or its affiliates. All rights reserved.
- * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
- *
- * This code is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 only, as
- * published by the Free Software Foundation.  Oracle designates this
- * particular file as subject to the "Classpath" exception as provided
- * by Oracle in the LICENSE file that accompanied this code.
- *
- * This code is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
- * version 2 for more details (a copy is included in the LICENSE file that
- * accompanied this code).
- *
- * You should have received a copy of the GNU General Public License version
- * 2 along with this work; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
- *
- * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
- * or visit www.oracle.com if you need additional information or have any
- * questions.
- */
-
-#include <jni.h>
-#include "jni_util.h"
-#include "com_sun_security_auth_module_UnixSystem.h"
-#include <stdio.h>
-#include <sys/types.h>
-#include <unistd.h>
-#include <stdlib.h>
-#include <string.h>
-
-#include <pwd.h>
-
-/*
- * Declare library specific JNI_Onload entry if static build
- */
-DEF_STATIC_JNI_OnLoad
-
-JNIEXPORT void JNICALL
-Java_com_sun_security_auth_module_UnixSystem_getUnixInfo
-                                                (JNIEnv *env, jobject obj) {
-
-    int i;
-    char pwd_buf[1024];
-    struct passwd *pwd = NULL;
-    struct passwd resbuf;
-    jfieldID userNameID;
-    jfieldID userID;
-    jfieldID groupID;
-    jfieldID supplementaryGroupID;
-
-    jstring jstr;
-    jlongArray jgroups;
-    jlong *jgroupsAsArray;
-    jsize numSuppGroups;
-    gid_t *groups;
-    jclass cls;
-
-    numSuppGroups = getgroups(0, NULL);
-    if (numSuppGroups == -1) {
-        return;
-    }
-    groups = (gid_t *)calloc(numSuppGroups, sizeof(gid_t));
-    if (groups == NULL) {
-        jclass cls = (*env)->FindClass(env,"java/lang/OutOfMemoryError");
-        if (cls != NULL) {
-            (*env)->ThrowNew(env, cls, NULL);
-        }
-        return;
-    }
-
-    cls = (*env)->GetObjectClass(env, obj);
-
-    supplementaryGroupID = (*env)->GetFieldID(env, cls, "groups", "[J");
-    if (supplementaryGroupID == 0) {
-        goto cleanUpAndReturn;
-    }
-
-    if (getgroups(numSuppGroups, groups) != -1) {
-        jgroups = (*env)->NewLongArray(env, numSuppGroups);
-        if (jgroups == NULL) {
-            goto cleanUpAndReturn;
-        }
-        jgroupsAsArray = (*env)->GetLongArrayElements(env, jgroups, 0);
-        if (jgroupsAsArray == NULL) {
-            goto cleanUpAndReturn;
-        }
-        for (i = 0; i < numSuppGroups; i++) {
-            jgroupsAsArray[i] = groups[i];
-        }
-        (*env)->ReleaseLongArrayElements(env, jgroups, jgroupsAsArray, 0);
-        (*env)->SetObjectField(env, obj, supplementaryGroupID, jgroups);
-    }
-
-    userNameID = (*env)->GetFieldID(env, cls, "username", "Ljava/lang/String;");
-    if (userNameID == 0) {
-        goto cleanUpAndReturn;
-    }
-
-    userID = (*env)->GetFieldID(env, cls, "uid", "J");
-    if (userID == 0) {
-        goto cleanUpAndReturn;
-    }
-
-    groupID = (*env)->GetFieldID(env, cls, "gid", "J");
-    if (groupID == 0) {
-        goto cleanUpAndReturn;
-    }
-
-    memset(pwd_buf, 0, sizeof(pwd_buf));
-    if (getpwuid_r(getuid(), &resbuf, pwd_buf, sizeof(pwd_buf), &pwd) == 0 &&
-            pwd != NULL) {
-        (*env)->SetLongField(env, obj, userID, pwd->pw_uid);
-        (*env)->SetLongField(env, obj, groupID, pwd->pw_gid);
-        jstr = (*env)->NewStringUTF(env, pwd->pw_name);
-        if (jstr == NULL) {
-            goto cleanUpAndReturn;
-        }
-        (*env)->SetObjectField(env, obj, userNameID, jstr);
-    } else {
-        (*env)->SetLongField(env, obj, userID, getuid());
-        (*env)->SetLongField(env, obj, groupID, getgid());
-    }
-cleanUpAndReturn:
-    free(groups);
-    return;
-}

test/jdk/com/sun/security/auth/module/AllPlatforms.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2014, 2025, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -25,8 +25,11 @@
  * @test
  * @bug 8039951
  * @summary com.sun.security.auth.module missing classes on some platforms
+ * @modules java.base/jdk.internal.util
  * @run main/othervm AllPlatforms
  */
+import jdk.internal.util.OperatingSystem;
+
 import javax.security.auth.login.Configuration;
 import javax.security.auth.login.LoginContext;
 import java.nio.file.Files;
@@ -39,14 +42,14 @@ public class AllPlatforms {
     private static final String NT_MODULE = "NTLoginModule";
 
     public static void main(String[] args) throws Exception {
-        login("cross-platform",
+        login(true, "cross-platform",
                 UNIX_MODULE, "optional",
                 NT_MODULE, "optional");
-        login("windows", NT_MODULE, "required");
+        login(OperatingSystem.isWindows(), "windows", NT_MODULE, "required");
-        login("unix", UNIX_MODULE, "required");
+        login(!OperatingSystem.isWindows(), "unix", UNIX_MODULE, "required");
     }
 
-    static void login(String test, String... conf) throws Exception {
+    static void login(boolean shouldSucceed, String test, String... conf) throws Exception {
         System.out.println("Testing " + test + "...");
 
         StringBuilder sb = new StringBuilder();
@@ -68,11 +71,19 @@ public class AllPlatforms {
             lc.login();
             System.out.println(lc.getSubject());
             lc.logout();
+            if (!shouldSucceed) {
+                throw new RuntimeException("Should not succeed");
+            }
         } catch (FailedLoginException e) {
+            if (shouldSucceed) {
+                throw new RuntimeException("Should succeed");
+            }
             // This exception can occur in other platform module than the running one.
-            if(e.getMessage().startsWith("Failed in attempt to import")) {
+            if (e.getMessage().startsWith("Failed in attempt to import")) {
                 System.out.println("Expected Exception found.");
                 e.printStackTrace(System.out);
+            } else {
+                throw new RuntimeException("Unexpected error", e);
             }
         }
     }