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Diffstat (limited to 'test/syscalls/linux/sticky.cc')
-rw-r--r-- | test/syscalls/linux/sticky.cc | 161 |
1 files changed, 161 insertions, 0 deletions
diff --git a/test/syscalls/linux/sticky.cc b/test/syscalls/linux/sticky.cc new file mode 100644 index 000000000..4afed6d08 --- /dev/null +++ b/test/syscalls/linux/sticky.cc @@ -0,0 +1,161 @@ +// 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))); + + const TempPath parent = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir()); + EXPECT_THAT(chmod(parent.path().c_str(), 0777 | S_ISVTX), SyscallSucceeds()); + + // After changing credentials below, we need to use an open fd to make + // modifications in the parent dir, because there is no guarantee that we will + // still have the ability to open it. + const FileDescriptor parent_fd = + ASSERT_NO_ERRNO_AND_VALUE(Open(parent.path(), O_DIRECTORY)); + ASSERT_THAT(openat(parent_fd.get(), "file", O_CREAT), SyscallSucceeds()); + ASSERT_THAT(mkdirat(parent_fd.get(), "dir", 0777), SyscallSucceeds()); + ASSERT_THAT(symlinkat("xyz", parent_fd.get(), "link"), 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(renameat(parent_fd.get(), "file", parent_fd.get(), "file2"), + SyscallFailsWithErrno(EPERM)); + EXPECT_THAT(unlinkat(parent_fd.get(), "file", 0), + SyscallFailsWithErrno(EPERM)); + EXPECT_THAT(unlinkat(parent_fd.get(), "dir", AT_REMOVEDIR), + SyscallFailsWithErrno(EPERM)); + EXPECT_THAT(unlinkat(parent_fd.get(), "link", 0), + SyscallFailsWithErrno(EPERM)); + }); +} + +TEST(StickyTest, StickyBitSameUID) { + SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SETUID))); + + const TempPath parent = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir()); + EXPECT_THAT(chmod(parent.path().c_str(), 0777 | S_ISVTX), SyscallSucceeds()); + + // After changing credentials below, we need to use an open fd to make + // modifications in the parent dir, because there is no guarantee that we will + // still have the ability to open it. + const FileDescriptor parent_fd = + ASSERT_NO_ERRNO_AND_VALUE(Open(parent.path(), O_DIRECTORY)); + ASSERT_THAT(openat(parent_fd.get(), "file", O_CREAT), SyscallSucceeds()); + ASSERT_THAT(mkdirat(parent_fd.get(), "dir", 0777), SyscallSucceeds()); + ASSERT_THAT(symlinkat("xyz", parent_fd.get(), "link"), 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(renameat(parent_fd.get(), "file", parent_fd.get(), "file2"), + SyscallSucceeds()); + EXPECT_THAT(unlinkat(parent_fd.get(), "file2", 0), SyscallSucceeds()); + EXPECT_THAT(unlinkat(parent_fd.get(), "dir", AT_REMOVEDIR), + SyscallSucceeds()); + EXPECT_THAT(unlinkat(parent_fd.get(), "link", 0), SyscallSucceeds()); + }); +} + +TEST(StickyTest, StickyBitCapFOWNER) { + SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SETUID))); + + const TempPath parent = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir()); + EXPECT_THAT(chmod(parent.path().c_str(), 0777 | S_ISVTX), SyscallSucceeds()); + + // After changing credentials below, we need to use an open fd to make + // modifications in the parent dir, because there is no guarantee that we will + // still have the ability to open it. + const FileDescriptor parent_fd = + ASSERT_NO_ERRNO_AND_VALUE(Open(parent.path(), O_DIRECTORY)); + ASSERT_THAT(openat(parent_fd.get(), "file", O_CREAT), SyscallSucceeds()); + ASSERT_THAT(mkdirat(parent_fd.get(), "dir", 0777), SyscallSucceeds()); + ASSERT_THAT(symlinkat("xyz", parent_fd.get(), "link"), 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(renameat(parent_fd.get(), "file", parent_fd.get(), "file2"), + SyscallSucceeds()); + EXPECT_THAT(unlinkat(parent_fd.get(), "file2", 0), SyscallSucceeds()); + EXPECT_THAT(unlinkat(parent_fd.get(), "dir", AT_REMOVEDIR), + SyscallSucceeds()); + EXPECT_THAT(unlinkat(parent_fd.get(), "link", 0), SyscallSucceeds()); + }); +} +} // namespace + +} // namespace testing +} // namespace gvisor |