Added stub FUSE filesystem

Allow FUSE filesystems to be mounted using libfuse.
The appropriate flags and mount options are parsed and
understood by fusefs.

2 files changed, 40 insertions, 0 deletions

diff --git a/test/syscalls/linux/dev.cc b/test/syscalls/linux/dev.cc
index 6fa16208e..69e8b76d3 100644
--- a/test/syscalls/linux/dev.cc
+++ b/test/syscalls/linux/dev.cc
@@ -161,6 +161,18 @@ TEST(DevTest, OpenDevFuse) {
   ASSERT_NO_ERRNO_AND_VALUE(Open("/dev/fuse", O_RDONLY));
 }
 
+TEST(DevTest, ReadDevFuseWithoutMount) {
+  // Note(gvisor.dev/issue/3076) This won't work in the sentry until the new
+  // device registration is complete.
+  SKIP_IF(IsRunningWithVFS1() || IsRunningOnGvisor());
+
+  const FileDescriptor fd =
+    ASSERT_NO_ERRNO_AND_VALUE(Open("/dev/fuse", O_RDONLY));
+
+  std::vector<char> buf(1);
+  EXPECT_THAT(ReadFd(fd.get(), buf.data(), sizeof(buf)), SyscallFailsWithErrno(EPERM));
+}
+
 }  // namespace
 }  // namespace testing
 
diff --git a/test/syscalls/linux/mount.cc b/test/syscalls/linux/mount.cc
index a3e9745cf..7664fa73d 100644
--- a/test/syscalls/linux/mount.cc
+++ b/test/syscalls/linux/mount.cc
@@ -321,6 +321,34 @@ TEST(MountTest, RenameRemoveMountPoint) {
   ASSERT_THAT(rmdir(dir.path().c_str()), SyscallFailsWithErrno(EBUSY));
 }
 
+TEST(MountTest, MountFuseFilesystemNoDevice) {
+  SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SYS_ADMIN)));
+
+  // Note(gvisor.dev/issue/3076) This won't work in the sentry until the new
+  // device registration is complete.
+  SKIP_IF(IsRunningWithVFS1() || IsRunningOnGvisor());
+
+  auto const dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir());
+  EXPECT_THAT(mount("", dir.path().c_str(), "fuse", 0, ""),
+              SyscallFailsWithErrno(EINVAL));
+}
+
+TEST(MountTest, MountFuseFilesystem) {
+  SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SYS_ADMIN)));
+
+  // Note(gvisor.dev/issue/3076) This won't work in the sentry until the new
+  // device registration is complete.
+  SKIP_IF(IsRunningWithVFS1() || IsRunningOnGvisor());
+
+  const FileDescriptor fd =
+      ASSERT_NO_ERRNO_AND_VALUE(Open("/dev/fuse", O_WRONLY));
+  std::string mopts = "fd=" + std::to_string(fd.get());
+
+  auto const dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir());
+  auto const mount =
+      ASSERT_NO_ERRNO_AND_VALUE(Mount("", dir.path(), "fuse", 0, mopts, 0));
+}
+
 }  // namespace
 
 }  // namespace testing