sandbox: remove seccomp-bpf demo program

sandbox/linux/seccomp-bpf/demo.cc

Index: sandbox/linux/seccomp-bpf/demo.cc
diff --git a/sandbox/linux/seccomp-bpf/demo.cc b/sandbox/linux/seccomp-bpf/demo.cc
deleted file mode 100644
index d9fd3423eeef5410d38f88137c1ab10ed12a5df8..0000000000000000000000000000000000000000
--- a/sandbox/linux/seccomp-bpf/demo.cc
+++ /dev/null
@@ -1,542 +0,0 @@
-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include <errno.h>
-#include <fcntl.h>
-#include <linux/unistd.h>
-#include <netinet/in.h>
-#include <netinet/tcp.h>
-#include <netinet/udp.h>
-#include <pthread.h>
-#include <signal.h>
-#include <stdarg.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <sys/ioctl.h>
-#include <sys/ipc.h>
-#include <sys/mman.h>
-#include <sys/prctl.h>
-#include <sys/resource.h>
-#include <sys/shm.h>
-#include <sys/socket.h>
-#include <sys/time.h>
-#include <sys/types.h>
-#include <time.h>
-#include <unistd.h>
-
-#include "base/macros.h"
-#include "base/posix/eintr_wrapper.h"
-#include "sandbox/linux/seccomp-bpf/sandbox_bpf.h"
-#include "sandbox/linux/seccomp-bpf/sandbox_bpf_policy.h"
-#include "sandbox/linux/services/linux_syscalls.h"
-
-using sandbox::ErrorCode;
-using sandbox::SandboxBPF;
-using sandbox::SandboxBPFPolicy;
-using sandbox::arch_seccomp_data;
-
-#define ERR EPERM
-
-// We don't expect our sandbox to do anything useful yet. So, we will fail
-// almost immediately. For now, force the code to continue running. The
-// following line should be removed as soon as the sandbox is starting to
-// actually enforce restrictions in a meaningful way:
-#define _exit(x) do { } while (0)
-
-namespace {
-
-bool SendFds(int transport, const void *buf, size_t len, ...) {
-  int count = 0;
-  va_list ap;
-  va_start(ap, len);
-  while (va_arg(ap, int) >= 0) {
-    ++count;
-  }
-  va_end(ap);
-  if (!count) {
-    return false;
-  }
-  char cmsg_buf[CMSG_SPACE(count*sizeof(int))];
-  memset(cmsg_buf, 0, sizeof(cmsg_buf));
-  struct iovec  iov[2] = { { 0 } };
-  struct msghdr msg    = { 0 };
-  int dummy            = 0;
-  iov[0].iov_base      = &dummy;
-  iov[0].iov_len       = sizeof(dummy);
-  if (buf && len > 0) {
-    iov[1].iov_base    = const_cast<void *>(buf);
-    iov[1].iov_len     = len;
-  }
-  msg.msg_iov          = iov;
-  msg.msg_iovlen       = (buf && len > 0) ? 2 : 1;
-  msg.msg_control      = cmsg_buf;
-  msg.msg_controllen   = CMSG_LEN(count*sizeof(int));
-  struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg);
-  cmsg->cmsg_level     = SOL_SOCKET;
-  cmsg->cmsg_type      = SCM_RIGHTS;
-  cmsg->cmsg_len       = CMSG_LEN(count*sizeof(int));
-  va_start(ap, len);
-  for (int i = 0, fd; (fd = va_arg(ap, int)) >= 0; ++i) {
-    (reinterpret_cast<int *>(CMSG_DATA(cmsg)))[i] = fd;
-  }
-  return sendmsg(transport, &msg, 0) ==
-      static_cast<ssize_t>(sizeof(dummy) + ((buf && len > 0) ? len : 0));
-}
-
-bool GetFds(int transport, void *buf, size_t *len, ...) {
-  int count = 0;
-  va_list ap;
-  va_start(ap, len);
-  for (int *fd; (fd = va_arg(ap, int *)) != NULL; ++count) {
-    *fd = -1;
-  }
-  va_end(ap);
-  if (!count) {
-    return false;
-  }
-  char cmsg_buf[CMSG_SPACE(count*sizeof(int))];
-  memset(cmsg_buf, 0, sizeof(cmsg_buf));
-  struct iovec iov[2] = { { 0 } };
-  struct msghdr msg   = { 0 };
-  int err;
-  iov[0].iov_base     = &err;
-  iov[0].iov_len      = sizeof(int);
-  if (buf && len && *len > 0) {
-    iov[1].iov_base   = buf;
-    iov[1].iov_len    = *len;
-  }
-  msg.msg_iov         = iov;
-  msg.msg_iovlen      = (buf && len && *len > 0) ? 2 : 1;
-  msg.msg_control     = cmsg_buf;
-  msg.msg_controllen  = CMSG_LEN(count*sizeof(int));
-  ssize_t bytes = recvmsg(transport, &msg, 0);
-  if (len) {
-    *len = bytes > static_cast<int>(sizeof(int)) ? bytes - sizeof(int) : 0;
-  }
-  if (bytes != static_cast<ssize_t>(sizeof(int) + iov[1].iov_len)) {
-    if (bytes >= 0) {
-      errno = 0;
-    }
-    return false;
-  }
-  if (err) {
-    // "err" is the first four bytes of the payload. If these are non-zero,
-    // the sender on the other side of the socketpair sent us an errno value.
-    // We don't expect to get any file handles in this case.
-    errno = err;
-    return false;
-  }
-  struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg);
-  if ((msg.msg_flags & (MSG_TRUNC|MSG_CTRUNC)) ||
-      !cmsg                                    ||
-      cmsg->cmsg_level != SOL_SOCKET           ||
-      cmsg->cmsg_type  != SCM_RIGHTS           ||
-      cmsg->cmsg_len   != CMSG_LEN(count*sizeof(int))) {
-    errno = EBADF;
-    return false;
-  }
-  va_start(ap, len);
-  for (int *fd, i = 0; (fd = va_arg(ap, int *)) != NULL; ++i) {
-    *fd = (reinterpret_cast<int *>(CMSG_DATA(cmsg)))[i];
-  }
-  va_end(ap);
-  return true;
-}
-
-
-// POSIX doesn't define any async-signal safe function for converting
-// an integer to ASCII. We'll have to define our own version.
-// itoa_r() converts a (signed) integer to ASCII. It returns "buf", if the
-// conversion was successful or NULL otherwise. It never writes more than "sz"
-// bytes. Output will be truncated as needed, and a NUL character is always
-// appended.
-char *itoa_r(int i, char *buf, size_t sz) {
-  // Make sure we can write at least one NUL byte.
-  size_t n = 1;
-  if (n > sz) {
-    return NULL;
-  }
-
-  // Handle negative numbers.
-  char *start = buf;
-  int minint = 0;
-  if (i < 0) {
-    // Make sure we can write the '-' character.
-    if (++n > sz) {
-      *start = '\000';
-      return NULL;
-    }
-    *start++ = '-';
-
-    // Turn our number positive.
-    if (i == -i) {
-      // The lowest-most negative integer needs special treatment.
-      minint = 1;
-      i = -(i + 1);
-    } else {
-      // "Normal" negative numbers are easy.
-      i = -i;
-    }
-  }
-
-  // Loop until we have converted the entire number. Output at least one
-  // character (i.e. '0').
-  char *ptr = start;
-  do {
-    // Make sure there is still enough space left in our output buffer.
-    if (++n > sz) {
-      buf = NULL;
-      goto truncate;
-    }
-
-    // Output the next digit and (if necessary) compensate for the lowest-most
-    // negative integer needing special treatment. This works because, no
-    // matter the bit width of the integer, the lowest-most integer always ends
-    // in 2, 4, 6, or 8.
-    *ptr++ = i%10 + '0' + minint;
-    minint = 0;
-    i /= 10;
-  } while (i);
- truncate:  // Terminate the output with a NUL character.
-  *ptr = '\000';
-
-  // Conversion to ASCII actually resulted in the digits being in reverse
-  // order. We can't easily generate them in forward order, as we can't tell
-  // the number of characters needed until we are done converting.
-  // So, now, we reverse the string (except for the possible "-" sign).
-  while (--ptr > start) {
-    char ch = *ptr;
-    *ptr = *start;
-    *start++ = ch;
-  }
-  return buf;
-}
-
-// This handler gets called, whenever we encounter a system call that we
-// don't recognize explicitly. For the purposes of this program, we just
-// log the system call and then deny it. More elaborate sandbox policies
-// might try to evaluate the system call in user-space, instead.
-// The only notable complication is that this function must be async-signal
-// safe. This restricts the libary functions that we can call.
-intptr_t DefaultHandler(const struct arch_seccomp_data& data, void *) {
-  static const char msg0[] = "Disallowed system call #";
-  static const char msg1[] = "\n";
-  char buf[sizeof(msg0) - 1 + 25 + sizeof(msg1)];
-
-  *buf = '\000';
-  strncat(buf, msg0, sizeof(buf) - 1);
-
-  char *ptr = strrchr(buf, '\000');
-  itoa_r(data.nr, ptr, sizeof(buf) - (ptr - buf));
-
-  ptr = strrchr(ptr, '\000');
-  strncat(ptr, msg1, sizeof(buf) - (ptr - buf));
-
-  ptr = strrchr(ptr, '\000');
-  if (HANDLE_EINTR(write(2, buf, ptr - buf))) { }
-
-  return -ERR;
-}
-
-class DemoPolicy : public SandboxBPFPolicy {
- public:
-  DemoPolicy() {}
-  virtual ErrorCode EvaluateSyscall(SandboxBPF* sandbox,
-                                    int sysno) const OVERRIDE;
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(DemoPolicy);
-};
-
-ErrorCode DemoPolicy::EvaluateSyscall(SandboxBPF* sandbox, int sysno) const {
-  switch (sysno) {
-#if defined(__NR_accept)
-  case __NR_accept: case __NR_accept4:
-#endif
-  case __NR_alarm:
-  case __NR_brk:
-  case __NR_clock_gettime:
-  case __NR_close:
-  case __NR_dup: case __NR_dup2:
-  case __NR_epoll_create: case __NR_epoll_ctl: case __NR_epoll_wait:
-  case __NR_exit: case __NR_exit_group:
-  case __NR_fcntl:
-#if defined(__NR_fcntl64)
-  case __NR_fcntl64:
-#endif
-  case __NR_fdatasync:
-  case __NR_fstat:
-#if defined(__NR_fstat64)
-  case __NR_fstat64:
-#endif
-  case __NR_ftruncate:
-  case __NR_futex:
-  case __NR_getdents: case __NR_getdents64:
-  case __NR_getegid:
-#if defined(__NR_getegid32)
-  case __NR_getegid32:
-#endif
-  case __NR_geteuid:
-#if defined(__NR_geteuid32)
-  case __NR_geteuid32:
-#endif
-  case __NR_getgid:
-#if defined(__NR_getgid32)
-  case __NR_getgid32:
-#endif
-  case __NR_getitimer: case __NR_setitimer:
-#if defined(__NR_getpeername)
-  case __NR_getpeername:
-#endif
-  case __NR_getpid: case __NR_gettid:
-#if defined(__NR_getsockname)
-  case __NR_getsockname:
-#endif
-  case __NR_gettimeofday:
-  case __NR_getuid:
-#if defined(__NR_getuid32)
-  case __NR_getuid32:
-#endif
-#if defined(__NR__llseek)
-  case __NR__llseek:
-#endif
-  case __NR_lseek:
-  case __NR_nanosleep:
-  case __NR_pipe: case __NR_pipe2:
-  case __NR_poll:
-  case __NR_pread64: case __NR_preadv:
-  case __NR_pwrite64: case __NR_pwritev:
-  case __NR_read: case __NR_readv:
-  case __NR_restart_syscall:
-  case __NR_set_robust_list:
-  case __NR_rt_sigaction:
-#if defined(__NR_sigaction)
-  case __NR_sigaction:
-#endif
-#if defined(__NR_signal)
-  case __NR_signal:
-#endif
-  case __NR_rt_sigprocmask:
-#if defined(__NR_sigprocmask)
-  case __NR_sigprocmask:
-#endif
-#if defined(__NR_shutdown)
-  case __NR_shutdown:
-#endif
-  case __NR_rt_sigreturn:
-#if defined(__NR_sigreturn)
-  case __NR_sigreturn:
-#endif
-#if defined(__NR_socketpair)
-  case __NR_socketpair:
-#endif
-  case __NR_time:
-  case __NR_uname:
-  case __NR_write: case __NR_writev:
-    return ErrorCode(ErrorCode::ERR_ALLOWED);
-
-  case __NR_prctl:
-    // Allow PR_SET_DUMPABLE and PR_GET_DUMPABLE. Do not allow anything else.
-    return sandbox->Cond(1, ErrorCode::TP_32BIT, ErrorCode::OP_EQUAL,
-                         PR_SET_DUMPABLE,
-                         ErrorCode(ErrorCode::ERR_ALLOWED),
-           sandbox->Cond(1, ErrorCode::TP_32BIT, ErrorCode::OP_EQUAL,
-                         PR_GET_DUMPABLE,
-                         ErrorCode(ErrorCode::ERR_ALLOWED),
-           sandbox->Trap(DefaultHandler, NULL)));
-
-  // The following system calls are temporarily permitted. This must be
-  // tightened later. But we currently don't implement enough of the sandboxing
-  // API to do so.
-  // As is, this sandbox isn't exactly safe :-/
-#if defined(__NR_sendmsg)
-  case __NR_sendmsg: case __NR_sendto:
-  case __NR_recvmsg: case __NR_recvfrom:
-  case __NR_getsockopt: case __NR_setsockopt:
-#elif defined(__NR_socketcall)
-  case __NR_socketcall:
-#endif
-#if defined(__NR_shmat)
-  case __NR_shmat: case __NR_shmctl: case __NR_shmdt: case __NR_shmget:
-#elif defined(__NR_ipc)
-  case __NR_ipc:
-#endif
-#if defined(__NR_mmap2)
-  case __NR_mmap2:
-#else
-  case __NR_mmap:
-#endif
-#if defined(__NR_ugetrlimit)
-  case __NR_ugetrlimit:
-#endif
-  case __NR_getrlimit:
-  case __NR_ioctl:
-  case __NR_clone:
-  case __NR_munmap: case __NR_mprotect: case __NR_madvise:
-  case __NR_remap_file_pages:
-    return ErrorCode(ErrorCode::ERR_ALLOWED);
-
-  // Everything that isn't explicitly allowed is denied.
-  default:
-    return sandbox->Trap(DefaultHandler, NULL);
-  }
-}
-
-void *ThreadFnc(void *arg) {
-  return arg;
-}
-
-void *SendmsgStressThreadFnc(void *arg) {
-  if (arg) { }
-  static const int repetitions = 100;
-  static const int kNumFds = 3;
-  for (int rep = 0; rep < repetitions; ++rep) {
-    int fds[2 + kNumFds];
-    if (socketpair(AF_UNIX, SOCK_STREAM, 0, fds)) {
-      perror("socketpair()");
-      _exit(1);
-    }
-    size_t len = 4;
-    char buf[4];
-    if (!SendFds(fds[0], "test", 4, fds[1], fds[1], fds[1], -1) ||
-        !GetFds(fds[1], buf, &len, fds+2, fds+3, fds+4, NULL) ||
-        len != 4 ||
-        memcmp(buf, "test", len) ||
-        write(fds[2], "demo", 4) != 4 ||
-        read(fds[0], buf, 4) != 4 ||
-        memcmp(buf, "demo", 4)) {
-      perror("sending/receiving of fds");
-      _exit(1);
-    }
-    for (int i = 0; i < 2+kNumFds; ++i) {
-      if (close(fds[i])) {
-        perror("close");
-        _exit(1);
-      }
-    }
-  }
-  return NULL;
-}
-
-}  // namespace
-
-int main(int argc, char *argv[]) {
-  if (argc) { }
-  if (argv) { }
-  int proc_fd = open("/proc", O_RDONLY|O_DIRECTORY);
-  if (SandboxBPF::SupportsSeccompSandbox(proc_fd) !=
-      SandboxBPF::STATUS_AVAILABLE) {
-    perror("sandbox");
-    _exit(1);
-  }
-  SandboxBPF sandbox;
-  sandbox.set_proc_fd(proc_fd);
-  sandbox.SetSandboxPolicy(new DemoPolicy());
-  if (!sandbox.StartSandbox(SandboxBPF::PROCESS_SINGLE_THREADED)) {
-    fprintf(stderr, "StartSandbox() failed");
-    _exit(1);
-  }
-
-  // Check that we can create threads
-  pthread_t thr;
-  if (!pthread_create(&thr, NULL, ThreadFnc,
-                      reinterpret_cast<void *>(0x1234))) {
-    void *ret;
-    pthread_join(thr, &ret);
-    if (ret != reinterpret_cast<void *>(0x1234)) {
-      perror("clone() failed");
-      _exit(1);
-    }
-  } else {
-    perror("clone() failed");
-    _exit(1);
-  }
-
-  // Check that we handle restart_syscall() without dieing. This is a little
-  // tricky to trigger. And I can't think of a good way to verify whether it
-  // actually executed.
-  signal(SIGALRM, SIG_IGN);
-  const struct itimerval tv = { { 0, 0 }, { 0, 5*1000 } };
-  const struct timespec tmo = { 0, 100*1000*1000 };
-  setitimer(ITIMER_REAL, &tv, NULL);
-  nanosleep(&tmo, NULL);
-
-  // Check that we can query the size of the stack, but that all other
-  // calls to getrlimit() fail.
-  if (((errno = 0), !getrlimit(RLIMIT_STACK, NULL)) || errno != EFAULT ||
-      ((errno = 0), !getrlimit(RLIMIT_CORE,  NULL)) || errno != ERR) {
-    perror("getrlimit()");
-    _exit(1);
-  }
-
-  // Check that we can query TCGETS and TIOCGWINSZ, but no other ioctls().
-  if (((errno = 0), !ioctl(2, TCGETS,     NULL)) || errno != EFAULT ||
-      ((errno = 0), !ioctl(2, TIOCGWINSZ, NULL)) || errno != EFAULT ||
-      ((errno = 0), !ioctl(2, TCSETS,     NULL)) || errno != ERR) {
-    perror("ioctl()");
-    _exit(1);
-  }
-
-  // Check that prctl() can manipulate the dumpable flag, but nothing else.
-  if (((errno = 0), !prctl(PR_GET_DUMPABLE))    || errno ||
-      ((errno = 0),  prctl(PR_SET_DUMPABLE, 1)) || errno ||
-      ((errno = 0), !prctl(PR_SET_SECCOMP,  0)) || errno != ERR) {
-    perror("prctl()");
-    _exit(1);
-  }
-
-  // Check that we can send and receive file handles.
-  int fds[3];
-  if (socketpair(AF_UNIX, SOCK_STREAM, 0, fds)) {
-    perror("socketpair()");
-    _exit(1);
-  }
-  size_t len = 4;
-  char buf[4];
-  if (!SendFds(fds[0], "test", 4, fds[1], -1) ||
-      !GetFds(fds[1], buf, &len, fds+2, NULL) ||
-      len != 4 ||
-      memcmp(buf, "test", len) ||
-      write(fds[2], "demo", 4) != 4 ||
-      read(fds[0], buf, 4) != 4 ||
-      memcmp(buf, "demo", 4) ||
-      close(fds[0]) ||
-      close(fds[1]) ||
-      close(fds[2])) {
-    perror("sending/receiving of fds");
-    _exit(1);
-  }
-
-  // Check whether SysV IPC works.
-  int shmid;
-  void *addr;
-  if ((shmid = shmget(IPC_PRIVATE, 4096, IPC_CREAT|0600)) < 0 ||
-      (addr = shmat(shmid, NULL, 0)) == reinterpret_cast<void *>(-1) ||
-      shmdt(addr) ||
-      shmctl(shmid, IPC_RMID, NULL)) {
-    perror("sysv IPC");
-    _exit(1);
-  }
-
-  // Print a message so that the user can see the sandbox is activated.
-  time_t tm = time(NULL);
-  printf("Sandbox has been started at %s", ctime(&tm));
-
-  // Stress-test the sendmsg() code
-  static const int kSendmsgStressNumThreads = 10;
-  pthread_t sendmsgStressThreads[kSendmsgStressNumThreads];
-  for (int i = 0; i < kSendmsgStressNumThreads; ++i) {
-    if (pthread_create(sendmsgStressThreads + i, NULL,
-                       SendmsgStressThreadFnc, NULL)) {
-      perror("pthread_create");
-      _exit(1);
-    }
-  }
-  for (int i = 0; i < kSendmsgStressNumThreads; ++i) {
-    pthread_join(sendmsgStressThreads[i], NULL);
-  }
-
-  return 0;
-}