Add verity symlink tests

PiperOrigin-RevId: 384823097

1 files changed, 117 insertions, 0 deletions

diff --git a/test/syscalls/linux/verity_symlink.cc b/test/syscalls/linux/verity_symlink.cc
new file mode 100644
index 000000000..bbf5375cb
--- /dev/null
+++ b/test/syscalls/linux/verity_symlink.cc
@@ -0,0 +1,117 @@
+// Copyright 2021 The gVisor Authors.
+//
+// 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 <stdint.h>
+#include <stdlib.h>
+#include <sys/mount.h>
+#include <sys/stat.h>
+
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+#include "test/util/capability_util.h"
+#include "test/util/fs_util.h"
+#include "test/util/mount_util.h"
+#include "test/util/temp_path.h"
+#include "test/util/test_util.h"
+#include "test/util/verity_util.h"
+
+namespace gvisor {
+namespace testing {
+
+namespace {
+
+const char kSymlink[] = "verity_symlink";
+
+class SymlinkTest : public ::testing::Test {
+ protected:
+  void SetUp() override {
+    // Verity is implemented in VFS2.
+    SKIP_IF(IsRunningWithVFS1());
+
+    SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SYS_ADMIN)));
+    // Mount a tmpfs file system, to be wrapped by a verity fs.
+    tmpfs_dir_ = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir());
+    ASSERT_THAT(mount("", tmpfs_dir_.path().c_str(), "tmpfs", 0, ""),
+                SyscallSucceeds());
+
+    // Create a new file in the tmpfs mount.
+    file_ = ASSERT_NO_ERRNO_AND_VALUE(
+        TempPath::CreateFileWith(tmpfs_dir_.path(), kContents, 0777));
+    filename_ = Basename(file_.path());
+
+    // Create a symlink to the file.
+    ASSERT_THAT(symlink(file_.path().c_str(),
+                        JoinPath(tmpfs_dir_.path(), kSymlink).c_str()),
+                SyscallSucceeds());
+  }
+
+  TempPath tmpfs_dir_;
+  TempPath file_;
+  std::string filename_;
+};
+
+TEST_F(SymlinkTest, Success) {
+  std::string verity_dir = ASSERT_NO_ERRNO_AND_VALUE(
+      MountVerity(tmpfs_dir_.path(), filename_,
+                  {EnableTarget(kSymlink, O_RDONLY | O_NOFOLLOW)}));
+
+  char buf[256];
+  EXPECT_THAT(
+      readlink(JoinPath(verity_dir, kSymlink).c_str(), buf, sizeof(buf)),
+      SyscallSucceeds());
+  auto const verity_fd = ASSERT_NO_ERRNO_AND_VALUE(
+      Open(JoinPath(verity_dir, kSymlink).c_str(), O_RDONLY, 0777));
+  EXPECT_THAT(ReadFd(verity_fd.get(), buf, sizeof(kContents)),
+              SyscallSucceeds());
+}
+
+TEST_F(SymlinkTest, DeleteLink) {
+  std::string verity_dir = ASSERT_NO_ERRNO_AND_VALUE(
+      MountVerity(tmpfs_dir_.path(), filename_,
+                  {EnableTarget(kSymlink, O_RDONLY | O_NOFOLLOW)}));
+
+  ASSERT_THAT(unlink(JoinPath(tmpfs_dir_.path(), kSymlink).c_str()),
+              SyscallSucceeds());
+  char buf[256];
+  EXPECT_THAT(
+      readlink(JoinPath(verity_dir, kSymlink).c_str(), buf, sizeof(buf)),
+      SyscallFailsWithErrno(EIO));
+  EXPECT_THAT(open(JoinPath(verity_dir, kSymlink).c_str(), O_RDONLY, 0777),
+              SyscallFailsWithErrno(EIO));
+}
+
+TEST_F(SymlinkTest, ModifyLink) {
+  std::string verity_dir = ASSERT_NO_ERRNO_AND_VALUE(
+      MountVerity(tmpfs_dir_.path(), filename_,
+                  {EnableTarget(kSymlink, O_RDONLY | O_NOFOLLOW)}));
+
+  ASSERT_THAT(unlink(JoinPath(tmpfs_dir_.path(), kSymlink).c_str()),
+              SyscallSucceeds());
+
+  std::string newlink = "newlink";
+  ASSERT_THAT(symlink(JoinPath(tmpfs_dir_.path(), newlink).c_str(),
+                      JoinPath(tmpfs_dir_.path(), kSymlink).c_str()),
+              SyscallSucceeds());
+  char buf[256];
+  EXPECT_THAT(
+      readlink(JoinPath(verity_dir, kSymlink).c_str(), buf, sizeof(buf)),
+      SyscallFailsWithErrno(EIO));
+  EXPECT_THAT(open(JoinPath(verity_dir, kSymlink).c_str(), O_RDONLY, 0777),
+              SyscallFailsWithErrno(EIO));
+}
+
+}  // namespace
+
+}  // namespace testing
+}  // namespace gvisor