Refactor Chrome's out-of-process Linux code into CrashGeneration{Server,Client} classes. Upstreamed from the Mozilla repository. Patch by Chris Jones <jones.chris.g@gmail.com> r=me at https://bugzilla.mozilla.org/show_bug.cgi?id=516759

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@515 4c0a9323-5329-0410-9bdc-e9ce6186880e

src/client/linux/crash_generation/crash_generation_server.cc

@@ -0,0 +1,466 @@
+// Copyright (c) 2009, Google Inc.
+// 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.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// 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 <assert.h>
+#include <dirent.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <poll.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "client/linux/crash_generation/crash_generation_server.h"
+#include "client/linux/crash_generation/client_info.h"
+#include "client/linux/handler/exception_handler.h"
+#include "client/linux/minidump_writer/minidump_writer.h"
+#include "common/linux/eintr_wrapper.h"
+#include "common/linux/guid_creator.h"
+
+static const char kCommandQuit = 'x';
+
+static bool
+GetInodeForFileDescriptor(ino_t* inode_out, int fd)
+{
+  assert(inode_out);
+
+  struct stat buf;
+  if (fstat(fd, &buf) < 0)
+    return false;
+
+  if (!S_ISSOCK(buf.st_mode))
+    return false;
+
+  *inode_out = buf.st_ino;
+  return true;
+}
+
+// expected prefix of the target of the /proc/self/fd/%d link for a socket
+static const char kSocketLinkPrefix[] = "socket:[";
+
+// Parse a symlink in /proc/pid/fd/$x and return the inode number of the
+// socket.
+//   inode_out: (output) set to the inode number on success
+//   path: e.g. /proc/1234/fd/5 (must be a UNIX domain socket descriptor)
+static bool
+GetInodeForProcPath(ino_t* inode_out, const char* path)
+{
+  assert(inode_out);
+  assert(path);
+
+  char buf[256];
+  const ssize_t n = readlink(path, buf, sizeof(buf) - 1);
+  if (n == -1) {
+    return false;
+  }
+  buf[n] = 0;
+
+  if (0 != memcmp(kSocketLinkPrefix, buf, sizeof(kSocketLinkPrefix) - 1)) {
+    return false;
+  }
+
+  char* endptr;
+  const u_int64_t inode_ul =
+      strtoull(buf + sizeof(kSocketLinkPrefix) - 1, &endptr, 10);
+  if (*endptr != ']')
+    return false;
+
+  if (inode_ul == ULLONG_MAX) {
+    return false;
+  }
+
+  *inode_out = inode_ul;
+  return true;
+}
+
+static bool
+FindProcessHoldingSocket(pid_t* pid_out, ino_t socket_inode)
+{
+  assert(pid_out);
+  bool already_found = false;
+
+  DIR* proc = opendir("/proc");
+  if (!proc) {
+    return false;
+  }
+
+  std::vector<pid_t> pids;
+
+  struct dirent* dent;
+  while ((dent = readdir(proc))) {
+    char* endptr;
+    const unsigned long int pid_ul = strtoul(dent->d_name, &endptr, 10);
+    if (pid_ul == ULONG_MAX || '\0' != *endptr)
+      continue;
+    pids.push_back(pid_ul);
+  }
+  closedir(proc);
+
+  for (std::vector<pid_t>::const_iterator
+       i = pids.begin(); i != pids.end(); ++i) {
+    const pid_t current_pid = *i;
+    char buf[256];
+    snprintf(buf, sizeof(buf), "/proc/%d/fd", current_pid);
+    DIR* fd = opendir(buf);
+    if (!fd)
+      continue;
+
+    while ((dent = readdir(fd))) {
+      if (snprintf(buf, sizeof(buf), "/proc/%d/fd/%s", current_pid,
+                   dent->d_name) >= static_cast<int>(sizeof(buf))) {
+        continue;
+      }
+
+      ino_t fd_inode;
+      if (GetInodeForProcPath(&fd_inode, buf)
+	  && fd_inode == socket_inode) {
+	if (already_found) {
+	  closedir(fd);
+	  return false;
+	}
+
+	already_found = true;
+	*pid_out = current_pid;
+	break;
+      }
+    }
+
+    closedir(fd);
+  }
+
+  return already_found;
+}
+
+namespace google_breakpad {
+
+CrashGenerationServer::CrashGenerationServer(
+  const int listen_fd,
+  OnClientDumpRequestCallback dump_callback,
+  void* dump_context,
+  OnClientExitingCallback exit_callback,
+  void* exit_context,
+  bool generate_dumps,
+  const std::string* dump_path) :
+    server_fd_(listen_fd),
+    dump_callback_(dump_callback),
+    dump_context_(dump_context),
+    exit_callback_(exit_callback),
+    exit_context_(exit_context),
+    generate_dumps_(generate_dumps),
+    started_(false)
+{
+  if (dump_path)
+    dump_dir_ = *dump_path;
+  else
+    dump_dir_ = "/tmp";
+}
+
+CrashGenerationServer::~CrashGenerationServer()
+{
+  if (started_)
+    Stop();
+}
+
+bool
+CrashGenerationServer::Start()
+{
+  if (started_ || 0 > server_fd_)
+    return false;
+
+  int control_pipe[2];
+  if (pipe(control_pipe))
+    return false;
+
+  if (fcntl(control_pipe[0], F_SETFD, FD_CLOEXEC))
+    return false;
+  if (fcntl(control_pipe[1], F_SETFD, FD_CLOEXEC))
+    return false;
+
+  if (fcntl(control_pipe[0], F_SETFL, O_NONBLOCK))
+    return false;
+
+  control_pipe_in_ = control_pipe[0];
+  control_pipe_out_ = control_pipe[1];
+
+  if (pthread_create(&thread_, NULL,
+                     ThreadMain, reinterpret_cast<void*>(this)))
+    return false;
+
+  started_ = true;
+  return true;
+}
+
+void
+CrashGenerationServer::Stop()
+{
+  assert(pthread_self() != thread_);
+
+ if (!started_)
+   return;
+
+  HANDLE_EINTR(write(control_pipe_out_, &kCommandQuit, 1));
+  
+  void* dummy;
+  pthread_join(thread_, &dummy);
+
+  started_ = false;
+}
+
+//static
+bool
+CrashGenerationServer::CreateReportChannel(int* server_fd, int* client_fd)
+{
+  int fds[2];
+
+  if (socketpair(AF_UNIX, SOCK_SEQPACKET, 0, fds))
+    return false;
+
+  static const int on = 1;
+  // Enable passcred on the server end of the socket
+  if (setsockopt(fds[1], SOL_SOCKET, SO_PASSCRED, &on, sizeof(on)))
+    return false;
+
+  if (fcntl(fds[1], F_SETFL, O_NONBLOCK))
+    return false;
+  if (fcntl(fds[1], F_SETFD, FD_CLOEXEC))
+    return false;
+
+  *client_fd = fds[0];
+  *server_fd = fds[1];
+  return true;
+}
+
+// The following methods/functions execute on the server thread
+
+void
+CrashGenerationServer::Run()
+{
+  struct pollfd pollfds[2];
+  memset(&pollfds, 0, sizeof(pollfds));
+
+  pollfds[0].fd = server_fd_;
+  pollfds[0].events = POLLIN;
+
+  pollfds[1].fd = control_pipe_in_;
+  pollfds[1].events = POLLIN;
+
+  while (true) {
+    // infinite timeout
+    int nevents = poll(pollfds, sizeof(pollfds)/sizeof(pollfds[0]), -1);
+    if (-1 == nevents) {
+      if (EINTR == errno) {
+        continue;
+      } else {
+	return;
+      }
+    }
+
+    if (pollfds[0].revents && !ClientEvent(pollfds[0].revents))
+      return;
+
+    if (pollfds[1].revents && !ControlEvent(pollfds[1].revents))
+      return;
+  }
+}
+
+bool
+CrashGenerationServer::ClientEvent(short revents)
+{
+  if (POLLHUP & revents)
+    return false;
+  assert(POLLIN & revents);
+
+  // A process has crashed and has signaled us by writing a datagram
+  // to the death signal socket. The datagram contains the crash context needed
+  // for writing the minidump as well as a file descriptor and a credentials
+  // block so that they can't lie about their pid.
+
+  // The length of the control message:
+  static const unsigned kControlMsgSize =
+      CMSG_SPACE(sizeof(int)) + CMSG_SPACE(sizeof(struct ucred));
+  // The length of the regular payload:
+  static const unsigned kCrashContextSize =
+      sizeof(google_breakpad::ExceptionHandler::CrashContext);
+
+  struct msghdr msg = {0};
+  struct iovec iov[1];
+  char crash_context[kCrashContextSize];
+  char control[kControlMsgSize];
+  const ssize_t expected_msg_size = sizeof(crash_context);
+
+  iov[0].iov_base = crash_context;
+  iov[0].iov_len = sizeof(crash_context);
+  msg.msg_iov = iov;
+  msg.msg_iovlen = sizeof(iov)/sizeof(iov[0]);
+  msg.msg_control = control;
+  msg.msg_controllen = kControlMsgSize;
+
+  const ssize_t msg_size = HANDLE_EINTR(recvmsg(server_fd_, &msg, 0));
+  if (msg_size != expected_msg_size)
+    return true;
+
+  if (msg.msg_controllen != kControlMsgSize ||
+      msg.msg_flags & ~MSG_TRUNC)
+    return true;
+
+  // Walk the control payload and extract the file descriptor and validated pid.
+  pid_t crashing_pid = -1;
+  int signal_fd = -1;
+  for (struct cmsghdr *hdr = CMSG_FIRSTHDR(&msg); hdr;
+       hdr = CMSG_NXTHDR(&msg, hdr)) {
+    if (hdr->cmsg_level != SOL_SOCKET)
+      continue;
+    if (hdr->cmsg_type == SCM_RIGHTS) {
+      const unsigned len = hdr->cmsg_len -
+          (((uint8_t*)CMSG_DATA(hdr)) - (uint8_t*)hdr);
+      assert(len % sizeof(int) == 0u);
+      const unsigned num_fds = len / sizeof(int);
+      if (num_fds > 1 || num_fds == 0) {
+        // A nasty process could try and send us too many descriptors and
+        // force a leak.
+        for (unsigned i = 0; i < num_fds; ++i)
+          HANDLE_EINTR(close(reinterpret_cast<int*>(CMSG_DATA(hdr))[i]));
+        return true;
+      } else {
+        signal_fd = reinterpret_cast<int*>(CMSG_DATA(hdr))[0];
+      }
+    } else if (hdr->cmsg_type == SCM_CREDENTIALS) {
+      const struct ucred *cred =
+          reinterpret_cast<struct ucred*>(CMSG_DATA(hdr));
+      crashing_pid = cred->pid;
+    }
+  }
+
+  if (crashing_pid == -1 || signal_fd == -1) {
+    if (signal_fd)
+      HANDLE_EINTR(close(signal_fd));
+    return true;
+  }
+
+  // Kernel bug workaround (broken in 2.6.30 at least):
+  // The kernel doesn't translate PIDs in SCM_CREDENTIALS across PID
+  // namespaces. Thus |crashing_pid| might be garbage from our point of view.
+  // In the future we can remove this workaround, but we have to wait a couple
+  // of years to be sure that it's worked its way out into the world.
+
+  ino_t inode_number;
+  if (!GetInodeForFileDescriptor(&inode_number, signal_fd)) {
+    HANDLE_EINTR(close(signal_fd));
+    return true;
+  }
+
+  if (!FindProcessHoldingSocket(&crashing_pid, inode_number - 1)) {
+    HANDLE_EINTR(close(signal_fd));
+    return true;
+  }
+
+  std::string minidump_filename;
+  if (!MakeMinidumpFilename(minidump_filename))
+    return true;
+
+  if (!google_breakpad::WriteMinidump(minidump_filename.c_str(),
+                                      crashing_pid, crash_context,
+                                      kCrashContextSize)) {
+    HANDLE_EINTR(close(signal_fd));
+    return true;
+  }
+
+  if (dump_callback_) {
+    ClientInfo info;
+
+    info.crash_server_ = this;
+    info.pid_ = crashing_pid;
+
+    dump_callback_(dump_context_, &info, &minidump_filename);
+  }
+
+  // Send the done signal to the process: it can exit now.
+  memset(&msg, 0, sizeof(msg));
+  struct iovec done_iov;
+  done_iov.iov_base = const_cast<char*>("\x42");
+  done_iov.iov_len = 1;
+  msg.msg_iov = &done_iov;
+  msg.msg_iovlen = 1;
+
+  HANDLE_EINTR(sendmsg(signal_fd, &msg, MSG_DONTWAIT | MSG_NOSIGNAL));
+  HANDLE_EINTR(close(signal_fd));
+
+  return true;
+}
+
+bool
+CrashGenerationServer::ControlEvent(short revents)
+{
+  if (POLLHUP & revents)
+    return false;
+  assert(POLLIN & revents);
+
+  char command;
+  if (read(control_pipe_in_, &command, 1))
+    return false;
+
+  switch (command) {
+  case kCommandQuit:
+    return false;
+  default:
+    assert(0);
+  }
+
+  return true;
+}
+
+bool
+CrashGenerationServer::MakeMinidumpFilename(std::string& outFilename)
+{
+  GUID guid;
+  char guidString[kGUIDStringLength+1];
+
+  if (!(CreateGUID(&guid)
+        && GUIDToString(&guid, guidString, sizeof(guidString))))
+    return false;
+
+  char path[PATH_MAX];
+  snprintf(path, sizeof(path), "%s/%s.dmp", dump_dir_.c_str(), guidString);
+
+  outFilename = path;
+  return true;
+}
+
+// static
+void*
+CrashGenerationServer::ThreadMain(void *arg)
+{
+  reinterpret_cast<CrashGenerationServer*>(arg)->Run();
+  return NULL;
+}
+
+} // namespace google_breakpad