sandbox/linux/integration_tests/namespace_unix_domain_socket_unittest.cc

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include <sched.h>
   6 #include <stdio.h>
   7 #include <string.h>
   8 #include <sys/socket.h>
   9 #include <sys/syscall.h>
  10 #include <sys/wait.h>
  11 #include <unistd.h>
  12
  13 #include <vector>
  14
  15 #include "base/files/scoped_file.h"
  16 #include "base/logging.h"
  17 #include "base/memory/scoped_vector.h"
  18 #include "base/posix/eintr_wrapper.h"
  19 #include "base/posix/unix_domain_socket_linux.h"
  20 #include "base/process/process.h"
  21 #include "sandbox/linux/services/syscall_wrappers.h"
  22 #include "sandbox/linux/tests/unit_tests.h"
  23
  24 // Additional tests for base's UnixDomainSocket to make sure it behaves
  25 // correctly in the presence of sandboxing functionality (e.g., receiving
  26 // PIDs across namespaces).
  27
  28 namespace sandbox {
  29
  30 namespace {
  31
  32 const char kHello[] = "hello";
  33
  34 // If the calling process isn't root, then try using unshare(CLONE_NEWUSER)
  35 // to fake it.
  36 void FakeRoot() {
  37   // If we're already root, then allow test to proceed.
  38   if (geteuid() == 0)
  39     return;
  40
  41   // Otherwise hope the kernel supports unprivileged namespaces.
  42   if (unshare(CLONE_NEWUSER) == 0)
  43     return;
  44
  45   printf("Permission to use CLONE_NEWPID missing; skipping test.\n");
  46   UnitTests::IgnoreThisTest();
  47 }
  48
  49 void WaitForExit(pid_t pid) {
  50   int status;
  51   CHECK_EQ(pid, HANDLE_EINTR(waitpid(pid, &status, 0)));
  52   CHECK(WIFEXITED(status));
  53   CHECK_EQ(0, WEXITSTATUS(status));
  54 }
  55
  56 base::ProcessId GetParentProcessId(base::ProcessId pid) {
  57   // base::GetParentProcessId() is defined as taking a ProcessHandle instead of
  58   // a ProcessId, even though it's a POSIX-only function and IDs and Handles
  59   // are both simply pid_t on POSIX... :/
  60   base::Process process = base::Process::Open(pid);
  61   CHECK(process.IsValid());
  62   base::ProcessId ret = base::GetParentProcessId(process.Handle());
  63   return ret;
  64 }
  65
  66 // SendHello sends a "hello" to socket fd, and then blocks until the recipient
  67 // acknowledges it by calling RecvHello.
  68 void SendHello(int fd) {
  69   int pipe_fds[2];
  70   CHECK_EQ(0, pipe(pipe_fds));
  71   base::ScopedFD read_pipe(pipe_fds[0]);
  72   base::ScopedFD write_pipe(pipe_fds[1]);
  73
  74   std::vector<int> send_fds;
  75   send_fds.push_back(write_pipe.get());
  76   CHECK(base::UnixDomainSocket::SendMsg(fd, kHello, sizeof(kHello), send_fds));
  77
  78   write_pipe.reset();
  79
  80   // Block until receiver closes their end of the pipe.
  81   char ch;
  82   CHECK_EQ(0, HANDLE_EINTR(read(read_pipe.get(), &ch, 1)));
  83 }
  84
  85 // RecvHello receives and acknowledges a "hello" on socket fd, and returns the
  86 // process ID of the sender in sender_pid.  Optionally, write_pipe can be used
  87 // to return a file descriptor, and the acknowledgement will be delayed until
  88 // the descriptor is closed.
  89 // (Implementation details: SendHello allocates a new pipe, sends us the writing
  90 // end alongside the "hello" message, and then blocks until we close the writing
  91 // end of the pipe.)
  92 void RecvHello(int fd,
  93                base::ProcessId* sender_pid,
  94                base::ScopedFD* write_pipe = NULL) {
  95   // Extra receiving buffer space to make sure we really received only
  96   // sizeof(kHello) bytes and it wasn't just truncated to fit the buffer.
  97   char buf[sizeof(kHello) + 1];
  98   ScopedVector<base::ScopedFD> message_fds;
  99   ssize_t n = base::UnixDomainSocket::RecvMsgWithPid(
 100       fd, buf, sizeof(buf), &message_fds, sender_pid);
 101   CHECK_EQ(sizeof(kHello), static_cast<size_t>(n));
 102   CHECK_EQ(0, memcmp(buf, kHello, sizeof(kHello)));
 103   CHECK_EQ(1U, message_fds.size());
 104   if (write_pipe)
 105     write_pipe->swap(*message_fds[0]);
 106 }
 107
 108 // Check that receiving PIDs works across a fork().
 109 SANDBOX_TEST(UnixDomainSocketTest, Fork) {
 110   int fds[2];
 111   CHECK_EQ(0, socketpair(AF_UNIX, SOCK_SEQPACKET, 0, fds));
 112   base::ScopedFD recv_sock(fds[0]);
 113   base::ScopedFD send_sock(fds[1]);
 114
 115   CHECK(base::UnixDomainSocket::EnableReceiveProcessId(recv_sock.get()));
 116
 117   const pid_t pid = fork();
 118   CHECK_NE(-1, pid);
 119   if (pid == 0) {
 120     // Child process.
 121     recv_sock.reset();
 122     SendHello(send_sock.get());
 123     _exit(0);
 124   }
 125
 126   // Parent process.
 127   send_sock.reset();
 128
 129   base::ProcessId sender_pid;
 130   RecvHello(recv_sock.get(), &sender_pid);
 131   CHECK_EQ(pid, sender_pid);
 132
 133   WaitForExit(pid);
 134 }
 135
 136 // Similar to Fork above, but forking the child into a new pid namespace.
 137 SANDBOX_TEST(UnixDomainSocketTest, Namespace) {
 138   FakeRoot();
 139
 140   int fds[2];
 141   CHECK_EQ(0, socketpair(AF_UNIX, SOCK_SEQPACKET, 0, fds));
 142   base::ScopedFD recv_sock(fds[0]);
 143   base::ScopedFD send_sock(fds[1]);
 144
 145   CHECK(base::UnixDomainSocket::EnableReceiveProcessId(recv_sock.get()));
 146
 147   const pid_t pid = sys_clone(CLONE_NEWPID | SIGCHLD, 0, 0, 0, 0);
 148   CHECK_NE(-1, pid);
 149   if (pid == 0) {
 150     // Child process.
 151     recv_sock.reset();
 152
 153     // Check that we think we're pid 1 in our new namespace.
 154     CHECK_EQ(1, sys_getpid());
 155
 156     SendHello(send_sock.get());
 157     _exit(0);
 158   }
 159
 160   // Parent process.
 161   send_sock.reset();
 162
 163   base::ProcessId sender_pid;
 164   RecvHello(recv_sock.get(), &sender_pid);
 165   CHECK_EQ(pid, sender_pid);
 166
 167   WaitForExit(pid);
 168 }
 169
 170 // Again similar to Fork, but now with nested PID namespaces.
 171 SANDBOX_TEST(UnixDomainSocketTest, DoubleNamespace) {
 172   FakeRoot();
 173
 174   int fds[2];
 175   CHECK_EQ(0, socketpair(AF_UNIX, SOCK_SEQPACKET, 0, fds));
 176   base::ScopedFD recv_sock(fds[0]);
 177   base::ScopedFD send_sock(fds[1]);
 178
 179   CHECK(base::UnixDomainSocket::EnableReceiveProcessId(recv_sock.get()));
 180
 181   const pid_t pid = sys_clone(CLONE_NEWPID | SIGCHLD, 0, 0, 0, 0);
 182   CHECK_NE(-1, pid);
 183   if (pid == 0) {
 184     // Child process.
 185     recv_sock.reset();
 186
 187     const pid_t pid2 = sys_clone(CLONE_NEWPID | SIGCHLD, 0, 0, 0, 0);
 188     CHECK_NE(-1, pid2);
 189
 190     if (pid2 != 0) {
 191       // Wait for grandchild to run to completion; see comments below.
 192       WaitForExit(pid2);
 193
 194       // Fallthrough once grandchild has sent its hello and exited.
 195     }
 196
 197     // Check that we think we're pid 1.
 198     CHECK_EQ(1, sys_getpid());
 199
 200     SendHello(send_sock.get());
 201     _exit(0);
 202   }
 203
 204   // Parent process.
 205   send_sock.reset();
 206
 207   // We have two messages to receive: first from the grand-child,
 208   // then from the child.
 209   for (unsigned iteration = 0; iteration < 2; ++iteration) {
 210     base::ProcessId sender_pid;
 211     base::ScopedFD pipe_fd;
 212     RecvHello(recv_sock.get(), &sender_pid, &pipe_fd);
 213
 214     // We need our child and grandchild processes to both be alive for
 215     // GetParentProcessId() to return a valid pid, hence the pipe trickery.
 216     // (On the first iteration, grandchild is blocked reading from the pipe
 217     // until we close it, and child is blocked waiting for grandchild to exit.)
 218     switch (iteration) {
 219       case 0:  // Grandchild's message
 220         // Check that sender_pid refers to our grandchild by checking that pid
 221         // (our child) is its parent.
 222         CHECK_EQ(pid, GetParentProcessId(sender_pid));
 223         break;
 224       case 1:  // Child's message
 225         CHECK_EQ(pid, sender_pid);
 226         break;
 227       default:
 228         NOTREACHED();
 229     }
 230   }
 231
 232   WaitForExit(pid);
 233 }
 234
 235 // Tests that GetPeerPid() returns 0 if the peer does not exist in caller's
 236 // namespace.
 237 SANDBOX_TEST(UnixDomainSocketTest, ImpossiblePid) {
 238   FakeRoot();
 239
 240   int fds[2];
 241   CHECK_EQ(0, socketpair(AF_UNIX, SOCK_SEQPACKET, 0, fds));
 242   base::ScopedFD send_sock(fds[0]);
 243   base::ScopedFD recv_sock(fds[1]);
 244
 245   CHECK(base::UnixDomainSocket::EnableReceiveProcessId(recv_sock.get()));
 246
 247   const pid_t pid = sys_clone(CLONE_NEWPID | SIGCHLD, 0, 0, 0, 0);
 248   CHECK_NE(-1, pid);
 249   if (pid == 0) {
 250     // Child process.
 251     send_sock.reset();
 252
 253     base::ProcessId sender_pid;
 254     RecvHello(recv_sock.get(), &sender_pid);
 255     CHECK_EQ(0, sender_pid);
 256     _exit(0);
 257   }
 258
 259   // Parent process.
 260   recv_sock.reset();
 261   SendHello(send_sock.get());
 262   WaitForExit(pid);
 263 }
 264
 265 }  // namespace
 266
 267 }  // namespace sandbox