1 files changed, 127 insertions, 0 deletions
diff --git a/test/syscalls/linux/sticky.cc b/test/syscalls/linux/sticky.cc
new file mode 100644
index 000000000..92eec0449
--- /dev/null
+++ b/test/syscalls/linux/sticky.cc
@@ -0,0 +1,127 @@
+// Copyright 2018 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 <fcntl.h>
+#include <grp.h>
+#include <sys/prctl.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <vector>
+
+#include "gtest/gtest.h"
+#include "absl/flags/flag.h"
+#include "test/util/capability_util.h"
+#include "test/util/file_descriptor.h"
+#include "test/util/fs_util.h"
+#include "test/util/temp_path.h"
+#include "test/util/test_util.h"
+#include "test/util/thread_util.h"
+
+ABSL_FLAG(int32_t, scratch_uid, 65534, "first scratch UID");
+ABSL_FLAG(int32_t, scratch_gid, 65534, "first scratch GID");
+
+namespace gvisor {
+namespace testing {
+
+namespace {
+
+TEST(StickyTest, StickyBitPermDenied) {
+  SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SETUID)));
+
+  auto dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir());
+  EXPECT_THAT(chmod(dir.path().c_str(), 0777 | S_ISVTX), SyscallSucceeds());
+  const FileDescriptor dirfd =
+      ASSERT_NO_ERRNO_AND_VALUE(Open(dir.path(), O_DIRECTORY));
+  ASSERT_THAT(mkdirat(dirfd.get(), "NewDir", 0755), SyscallSucceeds());
+
+  // Drop privileges and change IDs only in child thread, or else this parent
+  // thread won't be able to open some log files after the test ends.
+  ScopedThread([&] {
+    // Drop privileges.
+    if (HaveCapability(CAP_FOWNER).ValueOrDie()) {
+      EXPECT_NO_ERRNO(SetCapability(CAP_FOWNER, false));
+    }
+
+    // Change EUID and EGID.
+    EXPECT_THAT(
+        syscall(SYS_setresgid, -1, absl::GetFlag(FLAGS_scratch_gid), -1),
+        SyscallSucceeds());
+    EXPECT_THAT(
+        syscall(SYS_setresuid, -1, absl::GetFlag(FLAGS_scratch_uid), -1),
+        SyscallSucceeds());
+
+    EXPECT_THAT(unlinkat(dirfd.get(), "NewDir", AT_REMOVEDIR),
+                SyscallFailsWithErrno(EPERM));
+  });
+}
+
+TEST(StickyTest, StickyBitSameUID) {
+  SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SETUID)));
+
+  auto dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir());
+  EXPECT_THAT(chmod(dir.path().c_str(), 0777 | S_ISVTX), SyscallSucceeds());
+  std::string path = JoinPath(dir.path(), "NewDir");
+  ASSERT_THAT(mkdir(path.c_str(), 0755), SyscallSucceeds());
+
+  // Drop privileges and change IDs only in child thread, or else this parent
+  // thread won't be able to open some log files after the test ends.
+  ScopedThread([&] {
+    // Drop privileges.
+    if (HaveCapability(CAP_FOWNER).ValueOrDie()) {
+      EXPECT_NO_ERRNO(SetCapability(CAP_FOWNER, false));
+    }
+
+    // Change EGID.
+    EXPECT_THAT(
+        syscall(SYS_setresgid, -1, absl::GetFlag(FLAGS_scratch_gid), -1),
+        SyscallSucceeds());
+
+    // We still have the same EUID.
+    EXPECT_THAT(rmdir(path.c_str()), SyscallSucceeds());
+  });
+}
+
+TEST(StickyTest, StickyBitCapFOWNER) {
+  SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SETUID)));
+
+  auto dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir());
+  EXPECT_THAT(chmod(dir.path().c_str(), 0777 | S_ISVTX), SyscallSucceeds());
+  const FileDescriptor dirfd =
+      ASSERT_NO_ERRNO_AND_VALUE(Open(dir.path(), O_DIRECTORY));
+  ASSERT_THAT(mkdirat(dirfd.get(), "NewDir", 0755), SyscallSucceeds());
+
+  // Drop privileges and change IDs only in child thread, or else this parent
+  // thread won't be able to open some log files after the test ends.
+  ScopedThread([&] {
+    // Set PR_SET_KEEPCAPS.
+    EXPECT_THAT(prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0), SyscallSucceeds());
+
+    // Change EUID and EGID.
+    EXPECT_THAT(
+        syscall(SYS_setresgid, -1, absl::GetFlag(FLAGS_scratch_gid), -1),
+        SyscallSucceeds());
+    EXPECT_THAT(
+        syscall(SYS_setresuid, -1, absl::GetFlag(FLAGS_scratch_uid), -1),
+        SyscallSucceeds());
+
+    EXPECT_NO_ERRNO(SetCapability(CAP_FOWNER, true));
+    EXPECT_THAT(unlinkat(dirfd.get(), "NewDir", AT_REMOVEDIR),
+                SyscallSucceeds());
+  });
+}
+}  // namespace
+
+}  // namespace testing
+}  // namespace gvisor