Add verity_mmap tests

PiperOrigin-RevId: 373854462

4 files changed, 181 insertions, 102 deletions

diff --git a/test/syscalls/BUILD b/test/syscalls/BUILD
index 0435f61a2..85412f54b 100644
--- a/test/syscalls/BUILD
+++ b/test/syscalls/BUILD
@@ -313,6 +313,10 @@ syscall_test(
 )
 
 syscall_test(
+    test = "//test/syscalls/linux:verity_mmap_test",
+)
+
+syscall_test(
     add_overlay = True,
     test = "//test/syscalls/linux:mount_test",
 )
diff --git a/test/syscalls/linux/BUILD b/test/syscalls/linux/BUILD
index efed4aeb0..729b4c63b 100644
--- a/test/syscalls/linux/BUILD
+++ b/test/syscalls/linux/BUILD
@@ -1024,6 +1024,7 @@ cc_binary(
         "//test/util:temp_path",
         "//test/util:test_main",
         "//test/util:test_util",
+        "//test/util:verity_util",
     ],
 )
 
@@ -1294,6 +1295,23 @@ cc_binary(
 )
 
 cc_binary(
+    name = "verity_mmap_test",
+    testonly = 1,
+    srcs = ["verity_mmap.cc"],
+    linkstatic = 1,
+    deps = [
+        "//test/util:capability_util",
+        gtest,
+        "//test/util:fs_util",
+        "//test/util:memory_util",
+        "//test/util:temp_path",
+        "//test/util:test_main",
+        "//test/util:test_util",
+        "//test/util:verity_util",
+    ],
+)
+
+cc_binary(
     name = "mount_test",
     testonly = 1,
     srcs = ["mount.cc"],
diff --git a/test/syscalls/linux/verity_ioctl.cc b/test/syscalls/linux/verity_ioctl.cc
index 822e16f3c..be91b23d0 100644
--- a/test/syscalls/linux/verity_ioctl.cc
+++ b/test/syscalls/linux/verity_ioctl.cc
@@ -28,40 +28,13 @@
 #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 {
 
-#ifndef FS_IOC_ENABLE_VERITY
-#define FS_IOC_ENABLE_VERITY 1082156677
-#endif
-
-#ifndef FS_IOC_MEASURE_VERITY
-#define FS_IOC_MEASURE_VERITY 3221513862
-#endif
-
-#ifndef FS_VERITY_FL
-#define FS_VERITY_FL 1048576
-#endif
-
-#ifndef FS_IOC_GETFLAGS
-#define FS_IOC_GETFLAGS 2148034049
-#endif
-
-struct fsverity_digest {
-  __u16 digest_algorithm;
-  __u16 digest_size; /* input/output */
-  __u8 digest[];
-};
-
-constexpr int kMaxDigestSize = 64;
-constexpr int kDefaultDigestSize = 32;
-constexpr char kContents[] = "foobarbaz";
-constexpr char kMerklePrefix[] = ".merkle.verity.";
-constexpr char kMerkleRootPrefix[] = ".merkleroot.verity.";
-
 class IoctlTest : public ::testing::Test {
  protected:
   void SetUp() override {
@@ -85,80 +58,6 @@ class IoctlTest : public ::testing::Test {
   std::string filename_;
 };
 
-// Provide a function to convert bytes to hex string, since
-// absl::BytesToHexString does not seem to be compatible with golang
-// hex.DecodeString used in verity due to zero-padding.
-std::string BytesToHexString(uint8_t bytes[], int size) {
-  std::stringstream ss;
-  ss << std::hex;
-  for (int i = 0; i < size; ++i) {
-    ss << std::setw(2) << std::setfill('0') << static_cast<int>(bytes[i]);
-  }
-  return ss.str();
-}
-
-std::string MerklePath(absl::string_view path) {
-  return JoinPath(Dirname(path),
-                  std::string(kMerklePrefix) + std::string(Basename(path)));
-}
-
-std::string MerkleRootPath(absl::string_view path) {
-  return JoinPath(Dirname(path),
-                  std::string(kMerkleRootPrefix) + std::string(Basename(path)));
-}
-
-// Flip a random bit in the file represented by fd.
-PosixError FlipRandomBit(int fd, int size) {
-  // Generate a random offset in the file.
-  srand(time(nullptr));
-  unsigned int seed = 0;
-  int random_offset = rand_r(&seed) % size;
-
-  // Read a random byte and flip a bit in it.
-  char buf[1];
-  RETURN_ERROR_IF_SYSCALL_FAIL(PreadFd(fd, buf, 1, random_offset));
-  buf[0] ^= 1;
-  RETURN_ERROR_IF_SYSCALL_FAIL(PwriteFd(fd, buf, 1, random_offset));
-  return NoError();
-}
-
-// Mount a verity on the tmpfs and enable both the file and the direcotry. Then
-// mount a new verity with measured root hash.
-PosixErrorOr<std::string> MountVerity(std::string tmpfs_dir,
-                                      std::string filename) {
-  // Mount a verity fs on the existing tmpfs mount.
-  std::string mount_opts = "lower_path=" + tmpfs_dir;
-  ASSIGN_OR_RETURN_ERRNO(TempPath verity_dir, TempPath::CreateDir());
-  RETURN_ERROR_IF_SYSCALL_FAIL(
-      mount("", verity_dir.path().c_str(), "verity", 0, mount_opts.c_str()));
-
-  // Enable both the file and the directory.
-  ASSIGN_OR_RETURN_ERRNO(
-      auto fd, Open(JoinPath(verity_dir.path(), filename), O_RDONLY, 0777));
-  RETURN_ERROR_IF_SYSCALL_FAIL(ioctl(fd.get(), FS_IOC_ENABLE_VERITY));
-  ASSIGN_OR_RETURN_ERRNO(auto dir_fd, Open(verity_dir.path(), O_RDONLY, 0777));
-  RETURN_ERROR_IF_SYSCALL_FAIL(ioctl(dir_fd.get(), FS_IOC_ENABLE_VERITY));
-
-  // Measure the root hash.
-  uint8_t digest_array[sizeof(struct fsverity_digest) + kMaxDigestSize] = {0};
-  struct fsverity_digest* digest =
-      reinterpret_cast<struct fsverity_digest*>(digest_array);
-  digest->digest_size = kMaxDigestSize;
-  RETURN_ERROR_IF_SYSCALL_FAIL(
-      ioctl(dir_fd.get(), FS_IOC_MEASURE_VERITY, digest));
-
-  // Mount a verity fs with specified root hash.
-  mount_opts +=
-      ",root_hash=" + BytesToHexString(digest->digest, digest->digest_size);
-  ASSIGN_OR_RETURN_ERRNO(TempPath verity_with_hash_dir, TempPath::CreateDir());
-  RETURN_ERROR_IF_SYSCALL_FAIL(mount("", verity_with_hash_dir.path().c_str(),
-                                     "verity", 0, mount_opts.c_str()));
-  // Verity directories should not be deleted. Release the TempPath objects to
-  // prevent those directories from being deleted by the destructor.
-  verity_dir.release();
-  return verity_with_hash_dir.release();
-}
-
 TEST_F(IoctlTest, Enable) {
   // Mount a verity fs on the existing tmpfs mount.
   std::string mount_opts = "lower_path=" + tmpfs_dir_.path();
diff --git a/test/syscalls/linux/verity_mmap.cc b/test/syscalls/linux/verity_mmap.cc
new file mode 100644
index 000000000..dde74cc91
--- /dev/null
+++ b/test/syscalls/linux/verity_mmap.cc
@@ -0,0 +1,158 @@
+// 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/mman.h>
+#include <sys/mount.h>
+
+#include <string>
+
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+#include "test/util/capability_util.h"
+#include "test/util/fs_util.h"
+#include "test/util/memory_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 {
+
+class MmapTest : 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());
+  }
+
+  TempPath tmpfs_dir_;
+  TempPath file_;
+  std::string filename_;
+};
+
+TEST_F(MmapTest, MmapRead) {
+  std::string verity_dir =
+      ASSERT_NO_ERRNO_AND_VALUE(MountVerity(tmpfs_dir_.path(), filename_));
+
+  // Make sure the file can be open and mmapped in the mounted verity fs.
+  auto const verity_fd = ASSERT_NO_ERRNO_AND_VALUE(
+      Open(JoinPath(verity_dir, filename_), O_RDONLY, 0777));
+
+  Mapping const m =
+      ASSERT_NO_ERRNO_AND_VALUE(Mmap(nullptr, sizeof(kContents) - 1, PROT_READ,
+                                     MAP_SHARED, verity_fd.get(), 0));
+  EXPECT_THAT(std::string(m.view()), ::testing::StrEq(kContents));
+}
+
+TEST_F(MmapTest, ModifiedBeforeMmap) {
+  std::string verity_dir =
+      ASSERT_NO_ERRNO_AND_VALUE(MountVerity(tmpfs_dir_.path(), filename_));
+
+  // Modify the file and check verification failure upon mmapping.
+  auto const fd = ASSERT_NO_ERRNO_AND_VALUE(
+      Open(JoinPath(tmpfs_dir_.path(), filename_), O_RDWR, 0777));
+  ASSERT_NO_ERRNO(FlipRandomBit(fd.get(), sizeof(kContents) - 1));
+
+  auto const verity_fd = ASSERT_NO_ERRNO_AND_VALUE(
+      Open(JoinPath(verity_dir, filename_), O_RDONLY, 0777));
+  Mapping const m =
+      ASSERT_NO_ERRNO_AND_VALUE(Mmap(nullptr, sizeof(kContents) - 1, PROT_READ,
+                                     MAP_SHARED, verity_fd.get(), 0));
+
+  // Memory fault is expected when Translate fails.
+  EXPECT_EXIT(std::string(m.view()), ::testing::KilledBySignal(SIGSEGV), "");
+}
+
+TEST_F(MmapTest, ModifiedAfterMmap) {
+  std::string verity_dir =
+      ASSERT_NO_ERRNO_AND_VALUE(MountVerity(tmpfs_dir_.path(), filename_));
+
+  auto const verity_fd = ASSERT_NO_ERRNO_AND_VALUE(
+      Open(JoinPath(verity_dir, filename_), O_RDONLY, 0777));
+  Mapping const m =
+      ASSERT_NO_ERRNO_AND_VALUE(Mmap(nullptr, sizeof(kContents) - 1, PROT_READ,
+                                     MAP_SHARED, verity_fd.get(), 0));
+
+  // Modify the file after mapping and check verification failure upon mmapping.
+  auto const fd = ASSERT_NO_ERRNO_AND_VALUE(
+      Open(JoinPath(tmpfs_dir_.path(), filename_), O_RDWR, 0777));
+  ASSERT_NO_ERRNO(FlipRandomBit(fd.get(), sizeof(kContents) - 1));
+
+  // Memory fault is expected when Translate fails.
+  EXPECT_EXIT(std::string(m.view()), ::testing::KilledBySignal(SIGSEGV), "");
+}
+
+class MmapParamTest
+    : public MmapTest,
+      public ::testing::WithParamInterface<std::tuple<int, int>> {
+ protected:
+  int prot() const { return std::get<0>(GetParam()); }
+  int flags() const { return std::get<1>(GetParam()); }
+};
+
+INSTANTIATE_TEST_SUITE_P(
+    WriteExecNoneSharedPrivate, MmapParamTest,
+    ::testing::Combine(::testing::ValuesIn({
+                           PROT_WRITE,
+                           PROT_EXEC,
+                           PROT_NONE,
+                       }),
+                       ::testing::ValuesIn({MAP_SHARED, MAP_PRIVATE})));
+
+TEST_P(MmapParamTest, Mmap) {
+  std::string verity_dir =
+      ASSERT_NO_ERRNO_AND_VALUE(MountVerity(tmpfs_dir_.path(), filename_));
+
+  // Make sure the file can be open and mmapped in the mounted verity fs.
+  auto const verity_fd = ASSERT_NO_ERRNO_AND_VALUE(
+      Open(JoinPath(verity_dir, filename_), O_RDONLY, 0777));
+
+  if (prot() == PROT_WRITE && flags() == MAP_SHARED) {
+    // Verity file system is read-only.
+    EXPECT_THAT(
+        reinterpret_cast<intptr_t>(mmap(nullptr, sizeof(kContents) - 1, prot(),
+                                        flags(), verity_fd.get(), 0)),
+        SyscallFailsWithErrno(EACCES));
+  } else {
+    Mapping const m = ASSERT_NO_ERRNO_AND_VALUE(Mmap(
+        nullptr, sizeof(kContents) - 1, prot(), flags(), verity_fd.get(), 0));
+    if (prot() == PROT_NONE) {
+      // Memory mapped by MAP_NONE cannot be accessed.
+      EXPECT_EXIT(std::string(m.view()), ::testing::KilledBySignal(SIGSEGV),
+                  "");
+    } else {
+      EXPECT_THAT(std::string(m.view()), ::testing::StrEq(kContents));
+    }
+  }
+}
+
+}  // namespace
+
+}  // namespace testing
+}  // namespace gvisor