79 lines
2.8 KiB
C++
79 lines
2.8 KiB
C++
// Copyright 2018 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include <sys/ioctl.h>
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#include <termios.h>
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#include "gtest/gtest.h"
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#include "absl/base/macros.h"
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#include "test/util/capability_util.h"
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#include "test/util/file_descriptor.h"
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#include "test/util/posix_error.h"
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#include "test/util/pty_util.h"
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namespace gvisor {
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namespace testing {
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namespace {
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// StealTTY tests whether privileged processes can steal controlling terminals.
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// If the stealing process has CAP_SYS_ADMIN in the root user namespace, the
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// test ensures that stealing works. If it has non-root CAP_SYS_ADMIN, it
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// ensures stealing fails.
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TEST(JobControlRootTest, StealTTY) {
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SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SYS_ADMIN)));
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bool true_root = true;
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if (!IsRunningOnGvisor()) {
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// If running in Linux, we may only have CAP_SYS_ADMIN in a non-root user
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// namespace (i.e. we are not truly root). We use init_module as a proxy for
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// whether we are true root, as it returns EPERM immediately.
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ASSERT_THAT(syscall(SYS_init_module, nullptr, 0, nullptr), SyscallFails());
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true_root = errno != EPERM;
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// Make this a session leader, which also drops the controlling terminal.
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// In the gVisor test environment, this test will be run as the session
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// leader already (as the sentry init process).
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ASSERT_THAT(setsid(), SyscallSucceeds());
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}
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FileDescriptor master =
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ASSERT_NO_ERRNO_AND_VALUE(Open("/dev/ptmx", O_RDWR | O_NONBLOCK));
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FileDescriptor replica = ASSERT_NO_ERRNO_AND_VALUE(OpenReplica(master));
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// Make replica the controlling terminal.
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ASSERT_THAT(ioctl(replica.get(), TIOCSCTTY, 0), SyscallSucceeds());
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// Fork, join a new session, and try to steal the parent's controlling
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// terminal, which should succeed when we have CAP_SYS_ADMIN and pass an arg
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// of 1.
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pid_t child = fork();
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if (!child) {
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ASSERT_THAT(setsid(), SyscallSucceeds());
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// We shouldn't be able to steal the terminal with the wrong arg value.
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TEST_PCHECK(ioctl(replica.get(), TIOCSCTTY, 0));
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// We should be able to steal it if we are true root.
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TEST_PCHECK(true_root == !ioctl(replica.get(), TIOCSCTTY, 1));
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_exit(0);
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}
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int wstatus;
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ASSERT_THAT(waitpid(child, &wstatus, 0), SyscallSucceedsWithValue(child));
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ASSERT_EQ(wstatus, 0);
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}
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} // namespace
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} // namespace testing
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} // namespace gvisor
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