fs/fuse: check that a task has a specified file descriptor

Reported-by: syzbot+814105309d2ae8651084@syzkaller.appspotmail.com
PiperOrigin-RevId: 350159452

3 files changed, 43 insertions, 36 deletions

diff --git a/test/fuse/linux/BUILD b/test/fuse/linux/BUILD
index d1fb178e8..2f745bd47 100644
--- a/test/fuse/linux/BUILD
+++ b/test/fuse/linux/BUILD
@@ -235,6 +235,7 @@ cc_binary(
     srcs = ["mount_test.cc"],
     deps = [
         gtest,
+        "//test/util:mount_util",
         "//test/util:temp_path",
         "//test/util:test_main",
         "//test/util:test_util",
diff --git a/test/fuse/linux/mount_test.cc b/test/fuse/linux/mount_test.cc
index a5c2fbb01..8a5478116 100644
--- a/test/fuse/linux/mount_test.cc
+++ b/test/fuse/linux/mount_test.cc
@@ -17,6 +17,7 @@
 #include <sys/mount.h>
 
 #include "gtest/gtest.h"
+#include "test/util/mount_util.h"
 #include "test/util/temp_path.h"
 #include "test/util/test_util.h"
 
@@ -25,6 +26,17 @@ namespace testing {
 
 namespace {
 
+TEST(FuseMount, Success) {
+  const FileDescriptor fd =
+      ASSERT_NO_ERRNO_AND_VALUE(Open("/dev/fuse", O_WRONLY));
+  std::string mopts = absl::StrCat("fd=", std::to_string(fd.get()));
+
+  const auto dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir());
+
+  const auto mount =
+      ASSERT_NO_ERRNO_AND_VALUE(Mount("", dir.path(), "fuse", 0, mopts, 0));
+}
+
 TEST(FuseMount, FDNotParsable) {
   int devfd;
   EXPECT_THAT(devfd = open("/dev/fuse", O_RDWR), SyscallSucceeds());
@@ -35,6 +47,36 @@ TEST(FuseMount, FDNotParsable) {
               SyscallFailsWithErrno(EINVAL));
 }
 
+TEST(FuseMount, NoDevice) {
+  const auto dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir());
+
+  EXPECT_THAT(mount("", dir.path().c_str(), "fuse", 0, ""),
+              SyscallFailsWithErrno(EINVAL));
+}
+
+TEST(FuseMount, ClosedFD) {
+  FileDescriptor f = ASSERT_NO_ERRNO_AND_VALUE(Open("/dev/fuse", O_WRONLY));
+  int fd = f.release();
+  close(fd);
+  std::string mopts = absl::StrCat("fd=", std::to_string(fd));
+
+  const auto dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir());
+
+  EXPECT_THAT(mount("", dir.path().c_str(), "fuse", 0, mopts.c_str()),
+              SyscallFailsWithErrno(EINVAL));
+}
+
+TEST(FuseMount, BadFD) {
+  const auto dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir());
+  auto file = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFile());
+  const FileDescriptor fd =
+      ASSERT_NO_ERRNO_AND_VALUE(Open(file.path(), O_RDWR));
+  std::string mopts = absl::StrCat("fd=", std::to_string(fd.get()));
+
+  EXPECT_THAT(mount("", dir.path().c_str(), "fuse", 0, mopts.c_str()),
+              SyscallFailsWithErrno(EINVAL));
+}
+
 }  // namespace
 
 }  // namespace testing
diff --git a/test/syscalls/linux/mount.cc b/test/syscalls/linux/mount.cc
index d65b7d031..15b645fb7 100644
--- a/test/syscalls/linux/mount.cc
+++ b/test/syscalls/linux/mount.cc
@@ -345,42 +345,6 @@ 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)));
-  SKIP_IF(IsRunningOnGvisor() && !IsFUSEEnabled());
-
-  auto const dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir());
-
-  // Before kernel version 4.16-rc6, FUSE mount is protected by
-  // capable(CAP_SYS_ADMIN). After this version, it uses
-  // ns_capable(CAP_SYS_ADMIN) to protect. Before the 4.16 kernel, it was not
-  // allowed to mount fuse file systems without the global CAP_SYS_ADMIN.
-  int res = mount("", dir.path().c_str(), "fuse", 0, "");
-  SKIP_IF(!IsRunningOnGvisor() && res == -1 && errno == EPERM);
-
-  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)));
-  SKIP_IF(IsRunningOnGvisor() && !IsFUSEEnabled());
-
-  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());
-
-  // See comments in MountFuseFilesystemNoDevice for the reason why we skip
-  // EPERM when running on Linux.
-  int res = mount("", dir.path().c_str(), "fuse", 0, "");
-  SKIP_IF(!IsRunningOnGvisor() && res == -1 && errno == EPERM);
-
-  auto const mount =
-      ASSERT_NO_ERRNO_AND_VALUE(Mount("", dir.path(), "fuse", 0, mopts, 0));
-}
-
 }  // namespace
 
 }  // namespace testing