Merge changes from topic "memfd-ashmem-compat-platform-tests" into main
* changes:
ashmem_test: Add tests for memfd-ashmem compatibility layer
ashmem: Expose has_memfd_support() for ashmem-tests to use
diff --git a/libcutils/ashmem-dev.cpp b/libcutils/ashmem-dev.cpp
index 5fbe8a1..80c4f4c 100644
--- a/libcutils/ashmem-dev.cpp
+++ b/libcutils/ashmem-dev.cpp
@@ -44,6 +44,8 @@
#include <android-base/strings.h>
#include <android-base/unique_fd.h>
+#include "ashmem-internal.h"
+
/* ashmem identity */
static dev_t __ashmem_rdev;
/*
@@ -149,7 +151,7 @@
return true;
}
-static bool has_memfd_support() {
+bool has_memfd_support() {
static bool memfd_supported = __has_memfd_support();
return memfd_supported;
}
diff --git a/libcutils/ashmem-internal.h b/libcutils/ashmem-internal.h
new file mode 100644
index 0000000..7bd037b
--- /dev/null
+++ b/libcutils/ashmem-internal.h
@@ -0,0 +1,19 @@
+/*
+ * Copyright (C) 2025 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.
+ */
+
+#pragma once
+
+bool has_memfd_support();
diff --git a/libcutils/ashmem_test.cpp b/libcutils/ashmem_test.cpp
index 96f20db..2bf274c 100644
--- a/libcutils/ashmem_test.cpp
+++ b/libcutils/ashmem_test.cpp
@@ -29,6 +29,8 @@
#include <cutils/ashmem.h>
#include <gtest/gtest.h>
+#include "ashmem-internal.h"
+
using android::base::unique_fd;
static void TestCreateRegion(size_t size, unique_fd &fd, int prot) {
@@ -316,3 +318,119 @@
ASSERT_NO_FATAL_FAILURE(ForkMultiRegionTest(fds, nRegions, size));
}
+
+class AshmemTestMemfdAshmemCompat : public ::testing::Test {
+ protected:
+ void SetUp() override {
+ if (!has_memfd_support()){
+ GTEST_SKIP() << "No memfd support; skipping memfd-ashmem compat tests";
+ }
+ }
+};
+
+TEST_F(AshmemTestMemfdAshmemCompat, SetNameTest) {
+ unique_fd fd;
+
+ // ioctl() should fail, since memfd names cannot be changed after the buffer has been created.
+ ASSERT_NO_FATAL_FAILURE(TestCreateRegion(getpagesize(), fd, PROT_READ | PROT_WRITE |
+ PROT_EXEC));
+ ASSERT_LT(ioctl(fd, ASHMEM_SET_NAME, "invalid-command"), 0);
+}
+
+TEST_F(AshmemTestMemfdAshmemCompat, GetNameTest) {
+ unique_fd fd;
+ ASSERT_NO_FATAL_FAILURE(TestCreateRegion(getpagesize(), fd, PROT_READ | PROT_WRITE |
+ PROT_EXEC));
+
+ char testBuf[ASHMEM_NAME_LEN];
+ ASSERT_EQ(0, ioctl(fd, ASHMEM_GET_NAME, &testBuf));
+ // ashmem_create_region(nullptr, ...) creates memfds with the name "none".
+ ASSERT_STREQ(testBuf, "none");
+}
+
+TEST_F(AshmemTestMemfdAshmemCompat, SetSizeTest) {
+ unique_fd fd;
+
+ // ioctl() should fail, since libcutils sets and seals the buffer size after creating it.
+ ASSERT_NO_FATAL_FAILURE(TestCreateRegion(getpagesize(), fd, PROT_READ | PROT_WRITE |
+ PROT_EXEC));
+ ASSERT_LT(ioctl(fd, ASHMEM_SET_SIZE, 2 * getpagesize()), 0);
+}
+
+TEST_F(AshmemTestMemfdAshmemCompat, GetSizeTest) {
+ unique_fd fd;
+ size_t bufSize = getpagesize();
+
+ ASSERT_NO_FATAL_FAILURE(TestCreateRegion(bufSize, fd, PROT_READ | PROT_WRITE | PROT_EXEC));
+ ASSERT_EQ(static_cast<int>(bufSize), ioctl(fd, ASHMEM_GET_SIZE, 0));
+}
+
+TEST_F(AshmemTestMemfdAshmemCompat, ProtMaskTest) {
+ unique_fd fd;
+ ASSERT_NO_FATAL_FAILURE(TestCreateRegion(getpagesize(), fd, PROT_READ | PROT_WRITE |
+ PROT_EXEC));
+
+ // We can only change PROT_WRITE for memfds since memfd implements ashmem's prot_mask through
+ // file seals, and only write seals exist.
+ //
+ // All memfd files start off as being writable (i.e. PROT_WRITE is part of the prot_mask).
+ // Test to ensure that the implementation only clears the PROT_WRITE bit when requested.
+ ASSERT_EQ(0, ioctl(fd, ASHMEM_SET_PROT_MASK, PROT_READ | PROT_WRITE | PROT_EXEC));
+ int prot = ioctl(fd, ASHMEM_GET_PROT_MASK, 0);
+ ASSERT_NE(prot, -1);
+ ASSERT_TRUE(prot & PROT_WRITE) << prot;
+
+ ASSERT_EQ(0, ioctl(fd, ASHMEM_SET_PROT_MASK, PROT_READ | PROT_EXEC));
+ prot = ioctl(fd, ASHMEM_GET_PROT_MASK, 0);
+ ASSERT_NE(prot, -1);
+ ASSERT_TRUE(!(prot & PROT_WRITE)) << prot;
+
+ // The shim layer should implement clearing PROT_WRITE via file seals, so check the file
+ // seals to ensure that F_SEAL_FUTURE_WRITE is set.
+ int seals = fcntl(fd, F_GET_SEALS, 0);
+ ASSERT_NE(seals, -1);
+ ASSERT_TRUE(seals & F_SEAL_FUTURE_WRITE) << seals;
+
+ // Similarly, ensure that file seals affect prot_mask
+ unique_fd fd2;
+ ASSERT_NO_FATAL_FAILURE(TestCreateRegion(getpagesize(), fd2, PROT_READ | PROT_WRITE |
+ PROT_EXEC));
+ ASSERT_EQ(0, fcntl(fd2, F_ADD_SEALS, F_SEAL_FUTURE_WRITE));
+ prot = ioctl(fd2, ASHMEM_GET_PROT_MASK, 0);
+ ASSERT_NE(prot, -1);
+ ASSERT_TRUE(!(prot & PROT_WRITE)) << prot;
+
+ // And finally, ensure that adding back permissions fails
+ ASSERT_LT(ioctl(fd2, ASHMEM_SET_PROT_MASK, PROT_READ | PROT_WRITE | PROT_EXEC), 0);
+}
+
+TEST_F(AshmemTestMemfdAshmemCompat, FileIDTest) {
+ unique_fd fd;
+ ASSERT_NO_FATAL_FAILURE(TestCreateRegion(getpagesize(), fd, PROT_READ | PROT_WRITE |
+ PROT_EXEC));
+
+ unsigned long ino;
+ ASSERT_EQ(0, ioctl(fd, ASHMEM_GET_FILE_ID, &ino));
+ struct stat st;
+ ASSERT_EQ(0, fstat(fd, &st));
+ ASSERT_EQ(ino, st.st_ino);
+}
+
+TEST_F(AshmemTestMemfdAshmemCompat, UnpinningTest) {
+ unique_fd fd;
+ size_t bufSize = getpagesize();
+ ASSERT_NO_FATAL_FAILURE(TestCreateRegion(getpagesize(), fd, PROT_READ | PROT_WRITE |
+ PROT_EXEC));
+
+ struct ashmem_pin pin = {
+ .offset = 0,
+ .len = static_cast<uint32_t>(bufSize),
+ };
+ ASSERT_EQ(0, ioctl(fd, ASHMEM_UNPIN, &pin));
+ // ASHMEM_UNPIN should just be a nop
+ ASSERT_EQ(ASHMEM_IS_PINNED, ioctl(fd, ASHMEM_GET_PIN_STATUS, 0));
+
+ // This shouldn't do anything; when we pin the page, it shouldn't have been purged.
+ ASSERT_EQ(0, ioctl(fd, ASHMEM_PURGE_ALL_CACHES, 0));
+ ASSERT_EQ(ASHMEM_NOT_PURGED, ioctl(fd, ASHMEM_PIN, &pin));
+}
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