Merge "Add permissive MTE mode."

debuggerd/handler/debuggerd_handler.cpp

@@ -38,6 +38,8 @@
 #include <unistd.h>
 
 #include <android-base/macros.h>
+#include <android-base/parsebool.h>
+#include <android-base/properties.h>
 #include <android-base/unique_fd.h>
 #include <async_safe/log.h>
 #include <bionic/reserved_signals.h>
@@ -49,7 +51,10 @@
 
 #include "handler/fallback.h"
 
-using android::base::Pipe;
+using ::android::base::GetBoolProperty;
+using ::android::base::ParseBool;
+using ::android::base::ParseBoolResult;
+using ::android::base::Pipe;
 
 // We muck with our fds in a 'thread' that doesn't share the same fd table.
 // Close fds in that thread with a raw close syscall instead of going through libc.
@@ -82,6 +87,13 @@ static pid_t __gettid() {
   return syscall(__NR_gettid);
 }
 
+static bool is_permissive_mte() {
+  // Environment variable for testing or local use from shell.
+  char* permissive_env = getenv("MTE_PERMISSIVE");
+  return GetBoolProperty("persist.sys.mte.permissive", false) ||
+         (permissive_env && ParseBool(permissive_env) == ParseBoolResult::kTrue);
+}
+
 static inline void futex_wait(volatile void* ftx, int value) {
   syscall(__NR_futex, ftx, FUTEX_WAIT, value, nullptr, nullptr, 0);
 }
@@ -592,7 +604,28 @@ static void debuggerd_signal_handler(int signal_number, siginfo_t* info, void* c
     // If the signal is fatal, don't unlock the mutex to prevent other crashing threads from
     // starting to dump right before our death.
     pthread_mutex_unlock(&crash_mutex);
-  } else {
+  }
+#ifdef __aarch64__
+  else if (info->si_signo == SIGSEGV &&
+           (info->si_code == SEGV_MTESERR || info->si_code == SEGV_MTEAERR) &&
+           is_permissive_mte()) {
+    // If we are in permissive MTE mode, we do not crash, but instead disable MTE on this thread,
+    // and then let the failing instruction be retried. The second time should work (except
+    // if there is another non-MTE fault).
+    int tagged_addr_ctrl = prctl(PR_GET_TAGGED_ADDR_CTRL, 0, 0, 0, 0);
+    if (tagged_addr_ctrl < 0) {
+      fatal_errno("failed to PR_GET_TAGGED_ADDR_CTRL");
+    }
+    tagged_addr_ctrl = (tagged_addr_ctrl & ~PR_MTE_TCF_MASK) | PR_MTE_TCF_NONE;
+    if (prctl(PR_SET_TAGGED_ADDR_CTRL, tagged_addr_ctrl, 0, 0, 0) < 0) {
+      fatal_errno("failed to PR_SET_TAGGED_ADDR_CTRL");
+    }
+    async_safe_format_log(ANDROID_LOG_ERROR, "libc",
+                          "MTE ERROR DETECTED BUT RUNNING IN PERMISSIVE MODE. CONTINUING.");
+    pthread_mutex_unlock(&crash_mutex);
+  }
+#endif
+  else {
     // Resend the signal, so that either the debugger or the parent's waitpid sees it.
     resend_signal(info);
   }

debuggerd/test_permissive_mte/Android.bp

@@ -0,0 +1,34 @@
+// Copyright (C) 2022 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+cc_binary {
+  name: "mte_crash",
+  srcs: ["mte_crash.cpp"],
+  sanitize: {
+    memtag_heap: true,
+    diag: {
+      memtag_heap: true,
+    },
+  },
+}
+
+java_test_host {
+    name: "permissive_mte_test",
+    libs: ["tradefed"],
+    static_libs: ["frameworks-base-hostutils", "cts-install-lib-host"],
+    srcs:  ["src/**/PermissiveMteTest.java", ":libtombstone_proto-src"],
+    data: [":mte_crash"],
+    test_config: "AndroidTest.xml",
+    test_suites: ["general-tests"],
+}

debuggerd/test_permissive_mte/AndroidTest.xml

@@ -0,0 +1,29 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2022 The Android Open Source Project
+
+     Licensed under the Apache License, Version 2.0 (the "License");
+     you may not use this file except in compliance with the License.
+     You may obtain a copy of the License at
+
+          http://www.apache.org/licenses/LICENSE-2.0
+
+     Unless required by applicable law or agreed to in writing, software
+     distributed under the License is distributed on an "AS IS" BASIS,
+     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+     See the License for the specific language governing permissions and
+     limitations under the License.
+-->
+<configuration description="Runs the permissive MTE tests">
+    <option name="test-suite-tag" value="init_test_upgrade_mte" />
+    <option name="test-suite-tag" value="apct" />
+
+    <!-- For tombstone inspection. -->
+    <target_preparer class="com.android.tradefed.targetprep.RootTargetPreparer"/>
+    <target_preparer class="com.android.tradefed.targetprep.PushFilePreparer">
+      <option name="cleanup" value="true" />
+      <option name="push" value="mte_crash->/data/local/tmp/mte_crash" />
+    </target_preparer>
+    <test class="com.android.tradefed.testtype.HostTest" >
+        <option name="jar" value="permissive_mte_test.jar" />
+    </test>
+</configuration>

debuggerd/test_permissive_mte/mte_crash.cpp

@@ -0,0 +1,24 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+int main(int, char**) {
+  volatile char* f = (char*)malloc(1);
+  printf("%c\n", f[17]);
+  return 0;
+}

debuggerd/test_permissive_mte/src/com/android/tests/debuggerd/PermissiveMteTest.java

@@ -0,0 +1,100 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.tests.init;
+
+import static com.google.common.truth.Truth.assertThat;
+import static org.junit.Assume.assumeTrue;
+
+import com.android.server.os.TombstoneProtos.Tombstone;
+import com.android.tradefed.testtype.DeviceJUnit4ClassRunner;
+import com.android.tradefed.testtype.junit4.BaseHostJUnit4Test;
+import com.android.tradefed.util.CommandResult;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.InputStream;
+import java.util.Arrays;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+@RunWith(DeviceJUnit4ClassRunner.class)
+public class PermissiveMteTest extends BaseHostJUnit4Test {
+  String mUUID;
+
+  @Before
+  public void setUp() throws Exception {
+    mUUID = java.util.UUID.randomUUID().toString();
+    CommandResult result =
+        getDevice().executeShellV2Command("/data/local/tmp/mte_crash setUp " + mUUID);
+    assumeTrue("mte_crash needs to segfault", result.getExitCode() == 139);
+  }
+
+  Tombstone parseTombstone(String tombstonePath) throws Exception {
+    File tombstoneFile = getDevice().pullFile(tombstonePath);
+    InputStream istr = new FileInputStream(tombstoneFile);
+    Tombstone tombstoneProto;
+    try {
+      tombstoneProto = Tombstone.parseFrom(istr);
+    } finally {
+      istr.close();
+    }
+    return tombstoneProto;
+  }
+
+  @After
+  public void tearDown() throws Exception {
+    String[] tombstones = getDevice().getChildren("/data/tombstones");
+    for (String tombstone : tombstones) {
+      if (!tombstone.endsWith(".pb")) {
+        continue;
+      }
+      String tombstonePath = "/data/tombstones/" + tombstone;
+      Tombstone tombstoneProto = parseTombstone(tombstonePath);
+      if (!tombstoneProto.getCommandLineList().stream().anyMatch(x -> x.contains(mUUID))) {
+        continue;
+      }
+      getDevice().deleteFile(tombstonePath);
+      // remove the non .pb file as well.
+      getDevice().deleteFile(tombstonePath.substring(0, tombstonePath.length() - 3));
+    }
+  }
+
+  @Test
+  public void testCrash() throws Exception {
+    CommandResult result = getDevice().executeShellV2Command(
+        "MTE_PERMISSIVE=1 /data/local/tmp/mte_crash testCrash " + mUUID);
+    assertThat(result.getExitCode()).isEqualTo(0);
+    int numberTombstones = 0;
+    String[] tombstones = getDevice().getChildren("/data/tombstones");
+    for (String tombstone : tombstones) {
+      if (!tombstone.endsWith(".pb")) {
+        continue;
+      }
+      String tombstonePath = "/data/tombstones/" + tombstone;
+      Tombstone tombstoneProto = parseTombstone(tombstonePath);
+      if (!tombstoneProto.getCommandLineList().stream().anyMatch(x -> x.contains(mUUID))) {
+        continue;
+      }
+      if (!tombstoneProto.getCommandLineList().stream().anyMatch(x -> x.contains("testCrash"))) {
+        continue;
+      }
+      numberTombstones++;
+    }
+    assertThat(numberTombstones).isEqualTo(1);
+  }
+}