Add the SeatbeltExec classes to facilitate the V2 sandbox.

sandbox/mac/seatbelt_exec.cc

+// Copyright 2017 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 "sandbox/mac/seatbelt_exec.h"
+
+#include <sys/socket.h>
+#include <sys/uio.h>
+#include <unistd.h>
+
+#include <vector>
+
+#include "base/logging.h"
+#include "base/posix/eintr_wrapper.h"
+#include "base/strings/stringprintf.h"
+#include "sandbox/mac/seatbelt.h"
+
+namespace sandbox {
+
+SeatbeltExecClient::SeatbeltExecClient() {
+  PCHECK(pipe(pipe_) == 0) << "pipe";
+}
+
+SeatbeltExecClient::~SeatbeltExecClient() {
+  if (!got_fd_)
+    close(pipe_[1]);

[Robert Sesek, 2017/05/10 15:25:28]

Use IGNORE_EINTR.

[Greg K, 2017/05/11 17:44:15]

Done.

+
+  close(pipe_[0]);

[Robert Sesek, 2017/05/10 15:25:29]

Same.

[Greg K, 2017/05/11 17:44:15]

Done.

+}
+
+bool SeatbeltExecClient::SetBooleanParameter(const std::string& key,
+                                             bool value) {
+  google::protobuf::MapPair<std::string, std::string> pair(
+      key, value ? "TRUE" : "FALSE");
+  return params_.mutable_params()->insert(pair).second;
+}
+
+bool SeatbeltExecClient::SetParameter(const std::string& key,
+                                      const std::string& value) {
+  google::protobuf::MapPair<std::string, std::string> pair(key, value);
+  return params_.mutable_params()->insert(pair).second;
+}
+
+void SeatbeltExecClient::SetPolicy(const char* policy) {
+  params_.set_policy(policy);
+}
+
+int SeatbeltExecClient::GetSandboxFD() {
+  std::string serialized_protobuf;
+  if (!params_.SerializeToString(&serialized_protobuf))
+    LOG(FATAL) << "failed to serialize protobuf";

[Robert Sesek, 2017/05/10 15:25:29]

Why is this LOG(FATAL) and not a return -1?

[Greg K, 2017/05/11 17:44:15]

Done.

+
+  if (!WriteString(serialized_protobuf))
+    return -1;
+
+  got_fd_ = true;
+  close(pipe_[1]);
+
+  return pipe_[0];
+}
+
+bool SeatbeltExecClient::WriteString(const std::string& str) {
+  // iov takes a non-const pointer.

[Robert Sesek, 2017/05/10 15:25:28]

Can you use &str[0] ?

[Greg K, 2017/05/11 17:44:15]

The compiler says that &str[0] is also a const char *.

+  char buffer[str.size() + 1];
+  memcpy(buffer, str.c_str(), sizeof(buffer));
+
+  struct iovec iov[1];
+  iov[0].iov_base = buffer;
+  iov[0].iov_len = sizeof(buffer);
+
+  ssize_t written =
+      HANDLE_EINTR(writev(pipe_[1], iov, sizeof(iov) / sizeof(iov[0])));

[Robert Sesek, 2017/05/10 15:25:28]

Use arraysize().

[Greg K, 2017/05/11 17:44:15]

Done.

+  if (written < 0)
+    return false;

[Robert Sesek, 2017/05/10 15:25:29]

PLOG(ERROR)?

[Greg K, 2017/05/11 17:44:15]

Done.

+  return static_cast<uint64_t>(written) == str.size();
+}
+
+SeatbeltExecServer::SeatbeltExecServer(int fd) : fd_(fd) {}
+
+SeatbeltExecServer::~SeatbeltExecServer() {
+  close(fd_);
+}
+
+void SeatbeltExecServer::AllowProcessExec(const std::string& exec_path) {
+  exec_path_ = exec_path;
+}
+
+int SeatbeltExecServer::InitializeSandbox() {
+  std::string params_string;
+  if (!ReadString(&params_string)) {
+    LOG(ERROR) << "ReadString";

[Robert Sesek, 2017/05/10 15:25:28]

Not necessary to log here since ReadString logs internally.

[Greg K, 2017/05/11 17:44:15]

Done.

+    return -1;
+  }
+
+  mac::SandboxParams params;
+  if (!params.ParseFromString(params_string)) {
+    LOG(ERROR) << "ParseFromString failed";
+    return -1;
+  }
+
+  return ApplySandboxProfile(params);
+}
+
+int SeatbeltExecServer::ApplySandboxProfile(const mac::SandboxParams& params) {
+  std::vector<const char*> weak_params;
+  for (const auto& pair : params.params()) {
+    weak_params.push_back(pair.first.c_str());
+    weak_params.push_back(pair.second.c_str());
+  }
+  weak_params.push_back("EXECUTABLE_PATH");
+  weak_params.push_back(exec_path_.c_str());
+  weak_params.push_back("CHROMIUM_PID");

[Robert Sesek, 2017/05/10 15:25:28]

What's with this magic variable? //sandbox generally shouldn't know about
something that's so specific to //chrome or //content.

[Greg K, 2017/05/11 17:44:15]

The calling code will just add those as parameters.

+  weak_params.push_back(std::to_string(getppid()).c_str());
+  weak_params.push_back(nullptr);
+
+  char* error = nullptr;
+  int rv = Seatbelt::InitWithParams(params.policy().c_str(), 0,
+                                    weak_params.data(), &error);
+  if (error) {
+    LOG(ERROR) << "Failed to initialize sandbox: -" << rv << " " << error;

[Robert Sesek, 2017/05/10 17:53:28]

No need for the negative sign in the string, apparently.

[Greg K, 2017/05/11 17:44:15]

Done.

+    Seatbelt::FreeError(error);
+    return rv;
+  }
+
+  return rv;
+}
+
+bool SeatbeltExecServer::ReadString(std::string* str) {
+  // 4 pages of memory is enough to hold the sandbox profiles.
+  char buffer[4096 * 4];

[Robert Sesek, 2017/05/10 15:25:29]

Use std::vector<char> instead.

[Greg K, 2017/05/11 17:44:15]

Done.

+  memset(buffer, '\0', sizeof(buffer));
+
+  struct iovec iov[1];
+  iov[0].iov_base = buffer;
+  iov[0].iov_len = sizeof(buffer);
+
+  ssize_t read_length = readv(fd_, iov, sizeof(iov) / sizeof(iov[0]));

[Robert Sesek, 2017/05/10 15:25:28]

HANDLE_EINTR

[Robert Sesek, 2017/05/10 15:25:28]

Use arraysize().

[Greg K, 2017/05/11 17:44:14]

Done.

[Greg K, 2017/05/11 17:44:15]

Done.

[Greg K, 2017/05/11 17:44:15]

Done.

+  if (read_length < 0) {
+    PLOG(ERROR) << "ReadString";

[Robert Sesek, 2017/05/10 15:25:28]

"readv" not "ReadString"

[Greg K, 2017/05/11 17:44:14]

Done.

+    return false;
+  }
+  str->assign(buffer);
+  return true;
+}
+
+}  // namespace sandbox