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/*
* Copyright (C) 2018 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <dlfcn.h>
#include <pthread.h>
#include <signal.h>
#include <sys/syscall.h>
#include <functional>
#include <gtest/gtest.h>
#include "sigchain.h"
#if defined(__clang__) && __has_feature(hwaddress_sanitizer)
#define DISABLE_HWASAN __attribute__((no_sanitize("hwaddress")))
#else
#define DISABLE_HWASAN
#endif
#if !defined(__BIONIC__)
using sigset64_t = sigset_t;
static int sigemptyset64(sigset64_t* set) {
return sigemptyset(set);
}
static int sigismember64(sigset64_t* set, int member) {
return sigismember(set, member);
}
#endif
static int RealSigprocmask(int how, const sigset64_t* new_sigset, sigset64_t* old_sigset) {
// glibc's sigset_t is overly large, so sizeof(*new_sigset) doesn't work.
return syscall(__NR_rt_sigprocmask, how, new_sigset, old_sigset, NSIG/8);
}
class SigchainTest : public ::testing::Test {
void SetUp() final {
art::AddSpecialSignalHandlerFn(SIGSEGV, &action);
}
void TearDown() final {
art::RemoveSpecialSignalHandlerFn(SIGSEGV, action.sc_sigaction);
}
art::SigchainAction action = {
.sc_sigaction = [](int, siginfo_t* info, void*) -> bool {
return info->si_value.sival_ptr;
},
.sc_mask = {},
.sc_flags = 0,
};
protected:
void RaiseHandled() {
sigval value;
value.sival_ptr = &value;
// pthread_sigqueue would guarantee the signal is delivered to this
// thread, but it is a nonstandard extension and does not exist in
// musl. Gtest is single threaded, and these tests don't create any
// threads, so sigqueue can be used and will deliver to this thread.
sigqueue(getpid(), SIGSEGV, value);
}
void RaiseUnhandled() {
sigval value;
value.sival_ptr = nullptr;
sigqueue(getpid(), SIGSEGV, value);
}
};
static void TestSignalBlocking(const std::function<void()>& fn) {
// Unblock SIGSEGV, make sure it stays unblocked.
sigset64_t mask;
sigemptyset64(&mask);
ASSERT_EQ(0, RealSigprocmask(SIG_SETMASK, &mask, nullptr)) << strerror(errno);
fn();
if (testing::Test::HasFatalFailure()) return;
ASSERT_EQ(0, RealSigprocmask(SIG_SETMASK, nullptr, &mask));
ASSERT_FALSE(sigismember64(&mask, SIGSEGV));
}
TEST_F(SigchainTest, sigprocmask_setmask) {
TestSignalBlocking([]() {
sigset_t mask;
sigfillset(&mask);
ASSERT_EQ(0, sigprocmask(SIG_SETMASK, &mask, nullptr));
});
}
TEST_F(SigchainTest, sigprocmask_block) {
TestSignalBlocking([]() {
sigset_t mask;
sigfillset(&mask);
ASSERT_EQ(0, sigprocmask(SIG_BLOCK, &mask, nullptr));
});
}
// bionic-only wide variants for LP32.
#if defined(__BIONIC__)
TEST_F(SigchainTest, sigprocmask64_setmask) {
TestSignalBlocking([]() {
sigset64_t mask;
sigfillset64(&mask);
ASSERT_EQ(0, sigprocmask64(SIG_SETMASK, &mask, nullptr));
});
}
TEST_F(SigchainTest, sigprocmask64_block) {
TestSignalBlocking([]() {
sigset64_t mask;
sigfillset64(&mask);
ASSERT_EQ(0, sigprocmask64(SIG_BLOCK, &mask, nullptr));
});
}
TEST_F(SigchainTest, pthread_sigmask64_setmask) {
TestSignalBlocking([]() {
sigset64_t mask;
sigfillset64(&mask);
ASSERT_EQ(0, pthread_sigmask64(SIG_SETMASK, &mask, nullptr));
});
}
TEST_F(SigchainTest, pthread_sigmask64_block) {
TestSignalBlocking([]() {
sigset64_t mask;
sigfillset64(&mask);
ASSERT_EQ(0, pthread_sigmask64(SIG_BLOCK, &mask, nullptr));
});
}
#endif
// glibc doesn't implement most of these in terms of sigprocmask, which we rely on.
#if defined(__BIONIC__)
TEST_F(SigchainTest, pthread_sigmask_setmask) {
TestSignalBlocking([]() {
sigset_t mask;
sigfillset(&mask);
ASSERT_EQ(0, pthread_sigmask(SIG_SETMASK, &mask, nullptr));
});
}
TEST_F(SigchainTest, pthread_sigmask_block) {
TestSignalBlocking([]() {
sigset_t mask;
sigfillset(&mask);
ASSERT_EQ(0, pthread_sigmask(SIG_BLOCK, &mask, nullptr));
});
}
TEST_F(SigchainTest, sigset_mask) {
TestSignalBlocking([]() {
sigset(SIGSEGV, SIG_HOLD);
});
}
TEST_F(SigchainTest, sighold) {
TestSignalBlocking([]() {
sighold(SIGSEGV);
});
}
#if defined(__BIONIC__)
// Not exposed via headers, but the symbols are available if you declare them yourself.
extern "C" int sigblock(int);
extern "C" int sigsetmask(int);
#endif
TEST_F(SigchainTest, sigblock) {
TestSignalBlocking([]() {
int mask = ~0U;
ASSERT_EQ(0, sigblock(mask));
});
}
TEST_F(SigchainTest, sigsetmask) {
TestSignalBlocking([]() {
int mask = ~0U;
ASSERT_EQ(0, sigsetmask(mask));
});
}
#endif
// Make sure that we properly put ourselves back in front if we get circumvented.
TEST_F(SigchainTest, EnsureFrontOfChain) {
#if defined(__BIONIC__)
constexpr char kLibcSoName[] = "libc.so";
#elif defined(__GNU_LIBRARY__) && __GNU_LIBRARY__ == 6
constexpr char kLibcSoName[] = "libc.so.6";
#elif defined(ANDROID_HOST_MUSL)
constexpr char kLibcSoName[] = "libc_musl.so";
#else
#error Unknown libc
#endif
void* libc = dlopen(kLibcSoName, RTLD_LAZY | RTLD_NOLOAD);
ASSERT_TRUE(libc);
auto libc_sigaction = reinterpret_cast<decltype(&sigaction)>(dlsym(libc, "sigaction"));
ASSERT_TRUE(libc_sigaction);
static sig_atomic_t called = 0;
struct sigaction action = {};
action.sa_flags = SA_SIGINFO;
action.sa_sigaction = [](int, siginfo_t*, void*) { called = 1; };
ASSERT_EQ(0, libc_sigaction(SIGSEGV, &action, nullptr));
// Try before EnsureFrontOfChain.
RaiseHandled();
ASSERT_EQ(1, called);
called = 0;
RaiseUnhandled();
ASSERT_EQ(1, called);
called = 0;
// ...and after.
art::EnsureFrontOfChain(SIGSEGV);
RaiseHandled();
ASSERT_EQ(0, called);
RaiseUnhandled();
ASSERT_EQ(1, called);
called = 0;
}
#if defined(__aarch64__)
// The test intentionally dereferences (tagged) null to trigger SIGSEGV.
// We need to disable HWASAN since it would catch the dereference first.
DISABLE_HWASAN void fault_address_tag_impl() {
struct sigaction action = {};
action.sa_flags = SA_SIGINFO;
action.sa_sigaction = [](int, siginfo_t* siginfo, void*) {
_exit(reinterpret_cast<uintptr_t>(siginfo->si_addr) >> 56);
};
ASSERT_EQ(0, sigaction(SIGSEGV, &action, nullptr));
auto* tagged_null = reinterpret_cast<int*>(0x2bULL << 56);
EXPECT_EXIT({ volatile int load __attribute__((unused)) = *tagged_null; },
testing::ExitedWithCode(0), "");
// Our sigaction implementation always implements the "clear unknown bits"
// semantics for oldact.sa_flags regardless of kernel version so we rely on it
// here to test for kernel support for SA_EXPOSE_TAGBITS.
action.sa_flags = SA_SIGINFO | SA_EXPOSE_TAGBITS;
ASSERT_EQ(0, sigaction(SIGSEGV, &action, nullptr));
ASSERT_EQ(0, sigaction(SIGSEGV, nullptr, &action));
if (action.sa_flags & SA_EXPOSE_TAGBITS) {
EXPECT_EXIT({ volatile int load __attribute__((unused)) = *tagged_null; },
testing::ExitedWithCode(0x2b), "");
}
}
#endif
TEST_F(SigchainTest, fault_address_tag) {
#define SA_EXPOSE_TAGBITS 0x00000800
#if defined(__aarch64__)
fault_address_tag_impl();
#else
GTEST_SKIP() << "arm64 only";
#endif
}