103 lines
3.2 KiB
C++
103 lines
3.2 KiB
C++
#include "sandboxed_api/sandbox2/regs.h"
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#include <linux/filter.h>
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#include <linux/seccomp.h>
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#include <sys/prctl.h>
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#include <sys/ptrace.h>
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#include <sys/socket.h>
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#include <sys/wait.h>
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#include <syscall.h>
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#include <unistd.h>
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#include <cerrno>
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#include <cstdint>
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#include <cstdlib>
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#include <vector>
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#include "gmock/gmock.h"
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#include "gtest/gtest.h"
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#include "absl/log/check.h"
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#include "sandboxed_api/config.h"
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#include "sandboxed_api/sandbox2/sanitizer.h"
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#include "sandboxed_api/sandbox2/syscall.h"
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#include "sandboxed_api/sandbox2/util.h"
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#include "sandboxed_api/sandbox2/util/bpf_helper.h"
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#include "sandboxed_api/util/status_matchers.h"
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namespace sandbox2 {
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namespace {
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using ::sapi::IsOk;
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#define __WPTRACEEVENT(x) ((x & 0xff0000) >> 16)
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TEST(RegsTest, SkipSyscallWorks) {
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std::vector<sock_filter> policy = {
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LOAD_SYSCALL_NR,
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JEQ32(__NR_getpid, TRACE(0)),
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ALLOW,
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};
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sock_fprog prog = {
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.len = static_cast<uint8_t>(policy.size()),
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.filter = policy.data(),
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};
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// Create socketpair for synchronization
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int sv[2];
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ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, sv), 0);
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// Fork a child process to run the syscalls in.
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pid_t ppid = util::Syscall(__NR_gettid);
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pid_t pid = fork();
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ASSERT_NE(pid, -1);
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char c = 'C';
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if (pid == 0) {
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// Get ready for being ptraced.
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sanitizer::WaitForSanitizer();
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CHECK_EQ(prctl(PR_SET_DUMPABLE, 1), 0);
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prctl(PR_SET_PTRACER, ppid);
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CHECK_EQ(prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0), 0);
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CHECK_EQ(prctl(PR_SET_KEEPCAPS, 0), 0);
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// Notify parent that we're ready for ptrace.
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CHECK_EQ(write(sv[0], &c, 1), 1);
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// Apply seccomp policy
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CHECK_EQ(util::Syscall(__NR_seccomp, SECCOMP_SET_MODE_FILTER, 0,
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reinterpret_cast<uintptr_t>(&prog)),
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0);
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// Wait for tracer to be attached.
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CHECK_EQ(read(sv[0], &c, 1), 1);
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// Run the test syscall
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errno = 0;
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util::Syscall(__NR_getpid, 123, reinterpret_cast<uintptr_t>(&c), 1);
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_Exit(errno == ENOENT ? 0 : 1);
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}
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// Wait for child to be ready for ptrace
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ASSERT_EQ(read(sv[1], &c, 1), 1);
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ASSERT_EQ(ptrace(PTRACE_SEIZE, pid, 0, PTRACE_O_TRACESECCOMP), 0);
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// Notify child it has been ptraced.
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ASSERT_EQ(write(sv[1], &c, 1), 1);
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// Wait for seccomp TRACE stop
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int status;
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ASSERT_EQ(waitpid(pid, &status, __WNOTHREAD | __WALL | WUNTRACED), pid);
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ASSERT_TRUE(WIFSTOPPED(status));
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ASSERT_EQ(__WPTRACEEVENT(status), PTRACE_EVENT_SECCOMP);
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// Fetch the registers
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Regs regs(pid);
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ASSERT_THAT(regs.Fetch(), IsOk());
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// Check syscall arguments
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Syscall syscall = regs.ToSyscall(sapi::host_cpu::Architecture());
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EXPECT_EQ(syscall.nr(), __NR_getpid);
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EXPECT_EQ(syscall.args()[0], 123);
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EXPECT_EQ(syscall.args()[1], reinterpret_cast<uintptr_t>(&c));
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EXPECT_EQ(syscall.args()[2], 1);
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// Skip syscall
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ASSERT_THAT(regs.SkipSyscallReturnValue(-ENOENT), IsOk());
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// Continue&detach the child process
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ASSERT_EQ(ptrace(PTRACE_DETACH, pid, 0, 0), 0);
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// Wait for the child to exit
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ASSERT_EQ(waitpid(pid, &status, __WNOTHREAD | __WALL | WUNTRACED), pid);
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ASSERT_TRUE(WIFEXITED(status));
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EXPECT_EQ(WEXITSTATUS(status), 0);
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}
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} // namespace
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} // namespace sandbox2
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