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Diffstat (limited to 'test/syscalls/linux/prctl_setuid.cc')
| -rw-r--r-- | test/syscalls/linux/prctl_setuid.cc | 268 |
1 files changed, 0 insertions, 268 deletions
diff --git a/test/syscalls/linux/prctl_setuid.cc b/test/syscalls/linux/prctl_setuid.cc deleted file mode 100644 index c4e9cf528..000000000 --- a/test/syscalls/linux/prctl_setuid.cc +++ /dev/null @@ -1,268 +0,0 @@ -// 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 <sched.h> -#include <sys/prctl.h> - -#include <string> - -#include "gtest/gtest.h" -#include "absl/flags/flag.h" -#include "test/util/capability_util.h" -#include "test/util/logging.h" -#include "test/util/multiprocess_util.h" -#include "test/util/posix_error.h" -#include "test/util/test_util.h" -#include "test/util/thread_util.h" - -ABSL_FLAG(int32_t, scratch_uid, 65534, "scratch UID"); -// This flag is used to verify that after an exec PR_GET_KEEPCAPS -// returns 0, the return code will be offset by kPrGetKeepCapsExitBase. -ABSL_FLAG(bool, prctl_pr_get_keepcaps, false, - "If true the test will verify that prctl with pr_get_keepcaps" - "returns 0. The test will exit with the result of that check."); - -// These tests exist seperately from prctl because we need to start -// them as root. Setuid() has the behavior that permissions are fully -// removed if one of the UIDs were 0 before a setuid() call. This -// behavior can be changed by using PR_SET_KEEPCAPS and that is what -// is tested here. -// -// Reference setuid(2): -// The setuid() function checks the effective user ID of -// the caller and if it is the superuser, all process-related user ID's -// are set to uid. After this has occurred, it is impossible for the -// program to regain root privileges. -// -// Thus, a set-user-ID-root program wishing to temporarily drop root -// privileges, assume the identity of an unprivileged user, and then -// regain root privileges afterward cannot use setuid(). You can -// accomplish this with seteuid(2). -namespace gvisor { -namespace testing { - -// Offset added to exit code from test child to distinguish from other abnormal -// exits. -constexpr int kPrGetKeepCapsExitBase = 100; - -namespace { - -class PrctlKeepCapsSetuidTest : public ::testing::Test { - protected: - void SetUp() override { - // PR_GET_KEEPCAPS will only return 0 or 1 (on success). - ASSERT_THAT(original_keepcaps_ = prctl(PR_GET_KEEPCAPS, 0, 0, 0, 0), - SyscallSucceeds()); - ASSERT_TRUE(original_keepcaps_ == 0 || original_keepcaps_ == 1); - } - - void TearDown() override { - // Restore PR_SET_KEEPCAPS. - ASSERT_THAT(prctl(PR_SET_KEEPCAPS, original_keepcaps_, 0, 0, 0), - SyscallSucceeds()); - - // Verify that it was restored. - ASSERT_THAT(prctl(PR_GET_KEEPCAPS, 0, 0, 0, 0), - SyscallSucceedsWithValue(original_keepcaps_)); - } - - // The original keep caps value exposed so tests can use it if they need. - int original_keepcaps_ = 0; -}; - -// This test will verify that a bad value, eg. not 0 or 1 for -// PR_SET_KEEPCAPS will return EINVAL as required by prctl(2). -TEST_F(PrctlKeepCapsSetuidTest, PrctlBadArgsToKeepCaps) { - ASSERT_THAT(prctl(PR_SET_KEEPCAPS, 2, 0, 0, 0), - SyscallFailsWithErrno(EINVAL)); -} - -// This test will verify that a setuid(2) without PR_SET_KEEPCAPS will cause -// all capabilities to be dropped. -TEST_F(PrctlKeepCapsSetuidTest, SetUidNoKeepCaps) { - // getuid(2) never fails. - if (getuid() != 0) { - SKIP_IF(!IsRunningOnGvisor()); - FAIL() << "User is not root on gvisor platform."; - } - - // Do setuid in a separate thread so that after finishing this test, the - // process can still open files the test harness created before starting - // this test. Otherwise, the files are created by root (UID before the - // test), but cannot be opened by the `uid` set below after the test. After - // calling setuid(non-zero-UID), there is no way to get root privileges - // back. - ScopedThread([] { - // Start by verifying we have a capability. - TEST_CHECK(HaveCapability(CAP_SYS_ADMIN).ValueOrDie()); - - // Verify that PR_GET_KEEPCAPS is disabled. - ASSERT_THAT(prctl(PR_GET_KEEPCAPS, 0, 0, 0, 0), - SyscallSucceedsWithValue(0)); - - // Use syscall instead of glibc setuid wrapper because we want this setuid - // call to only apply to this task. POSIX threads, however, require that - // all threads have the same UIDs, so using the setuid wrapper sets all - // threads' real UID. - EXPECT_THAT(syscall(SYS_setuid, absl::GetFlag(FLAGS_scratch_uid)), - SyscallSucceeds()); - - // Verify that we changed uid. - EXPECT_THAT(getuid(), - SyscallSucceedsWithValue(absl::GetFlag(FLAGS_scratch_uid))); - - // Verify we lost the capability in the effective set, this always happens. - TEST_CHECK(!HaveCapability(CAP_SYS_ADMIN).ValueOrDie()); - - // We should have also lost it in the permitted set by the setuid() so - // SetCapability should fail when we try to add it back to the effective set - ASSERT_FALSE(SetCapability(CAP_SYS_ADMIN, true).ok()); - }); -} - -// This test will verify that a setuid with PR_SET_KEEPCAPS will cause -// capabilities to be retained after we switch away from the root user. -TEST_F(PrctlKeepCapsSetuidTest, SetUidKeepCaps) { - // getuid(2) never fails. - if (getuid() != 0) { - SKIP_IF(!IsRunningOnGvisor()); - FAIL() << "User is not root on gvisor platform."; - } - - // Do setuid in a separate thread so that after finishing this test, the - // process can still open files the test harness created before starting - // this test. Otherwise, the files are created by root (UID before the - // test), but cannot be opened by the `uid` set below after the test. After - // calling setuid(non-zero-UID), there is no way to get root privileges - // back. - ScopedThread([] { - // Start by verifying we have a capability. - TEST_CHECK(HaveCapability(CAP_SYS_ADMIN).ValueOrDie()); - - // Set PR_SET_KEEPCAPS. - ASSERT_THAT(prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0), SyscallSucceeds()); - - // Verify PR_SET_KEEPCAPS was set before we proceed. - ASSERT_THAT(prctl(PR_GET_KEEPCAPS, 0, 0, 0, 0), - SyscallSucceedsWithValue(1)); - - // Use syscall instead of glibc setuid wrapper because we want this setuid - // call to only apply to this task. POSIX threads, however, require that - // all threads have the same UIDs, so using the setuid wrapper sets all - // threads' real UID. - EXPECT_THAT(syscall(SYS_setuid, absl::GetFlag(FLAGS_scratch_uid)), - SyscallSucceeds()); - - // Verify that we changed uid. - EXPECT_THAT(getuid(), - SyscallSucceedsWithValue(absl::GetFlag(FLAGS_scratch_uid))); - - // Verify we lost the capability in the effective set, this always happens. - TEST_CHECK(!HaveCapability(CAP_SYS_ADMIN).ValueOrDie()); - - // We lost the capability in the effective set, but it will still - // exist in the permitted set so we can elevate the capability. - ASSERT_NO_ERRNO(SetCapability(CAP_SYS_ADMIN, true)); - - // Verify we got back the capability in the effective set. - TEST_CHECK(HaveCapability(CAP_SYS_ADMIN).ValueOrDie()); - }); -} - -// This test will verify that PR_SET_KEEPCAPS is not retained -// across an execve. According to prctl(2): -// "The "keep capabilities" value will be reset to 0 on subsequent -// calls to execve(2)." -TEST_F(PrctlKeepCapsSetuidTest, NoKeepCapsAfterExec) { - ASSERT_THAT(prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0), SyscallSucceeds()); - - // Verify PR_SET_KEEPCAPS was set before we proceed. - ASSERT_THAT(prctl(PR_GET_KEEPCAPS, 0, 0, 0, 0), SyscallSucceedsWithValue(1)); - - pid_t child_pid = -1; - int execve_errno = 0; - // Do an exec and then verify that PR_GET_KEEPCAPS returns 0 - // see the body of main below. - auto cleanup = ASSERT_NO_ERRNO_AND_VALUE(ForkAndExec( - "/proc/self/exe", {"/proc/self/exe", "--prctl_pr_get_keepcaps"}, {}, - nullptr, &child_pid, &execve_errno)); - - ASSERT_GT(child_pid, 0); - ASSERT_EQ(execve_errno, 0); - - int status = 0; - ASSERT_THAT(RetryEINTR(waitpid)(child_pid, &status, 0), SyscallSucceeds()); - ASSERT_TRUE(WIFEXITED(status)); - // PR_SET_KEEPCAPS should have been cleared by the exec. - // Success should return gvisor::testing::kPrGetKeepCapsExitBase + 0 - ASSERT_EQ(WEXITSTATUS(status), kPrGetKeepCapsExitBase); -} - -TEST_F(PrctlKeepCapsSetuidTest, NoKeepCapsAfterNewUserNamespace) { - SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(CanCreateUserNamespace())); - - // Fork to avoid changing the user namespace of the original test process. - pid_t const child_pid = fork(); - - if (child_pid == 0) { - // Verify that the keepcaps flag is set to 0 when we change user namespaces. - TEST_PCHECK(prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0) == 0); - MaybeSave(); - - TEST_PCHECK(prctl(PR_GET_KEEPCAPS, 0, 0, 0, 0) == 1); - MaybeSave(); - - TEST_PCHECK(unshare(CLONE_NEWUSER) == 0); - MaybeSave(); - - TEST_PCHECK(prctl(PR_GET_KEEPCAPS, 0, 0, 0, 0) == 0); - MaybeSave(); - - _exit(0); - } - - int status; - ASSERT_THAT(child_pid, SyscallSucceeds()); - ASSERT_THAT(waitpid(child_pid, &status, 0), - SyscallSucceedsWithValue(child_pid)); - EXPECT_TRUE(WIFEXITED(status) && WEXITSTATUS(status) == 0) - << "status = " << status; -} - -// This test will verify that PR_SET_KEEPCAPS and PR_GET_KEEPCAPS work correctly -TEST_F(PrctlKeepCapsSetuidTest, PrGetKeepCaps) { - // Set PR_SET_KEEPCAPS to the negation of the original. - ASSERT_THAT(prctl(PR_SET_KEEPCAPS, !original_keepcaps_, 0, 0, 0), - SyscallSucceeds()); - - // Verify it was set. - ASSERT_THAT(prctl(PR_GET_KEEPCAPS, 0, 0, 0, 0), - SyscallSucceedsWithValue(!original_keepcaps_)); -} - -} // namespace - -} // namespace testing -} // namespace gvisor - -int main(int argc, char** argv) { - gvisor::testing::TestInit(&argc, &argv); - - if (absl::GetFlag(FLAGS_prctl_pr_get_keepcaps)) { - return gvisor::testing::kPrGetKeepCapsExitBase + - prctl(PR_GET_KEEPCAPS, 0, 0, 0, 0); - } - - return gvisor::testing::RunAllTests(); -} |