remoting/host/pam_authorization_factory_posix.cc

   1 // Copyright (c) 2012 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 "remoting/host/pam_authorization_factory_posix.h"
   6
   7 #include <security/pam_appl.h>
   8
   9 #include "base/bind.h"
  10 #include "base/callback.h"
  11 #include "base/environment.h"
  12 #include "remoting/base/logging.h"
  13 #include "remoting/host/username.h"
  14 #include "remoting/protocol/channel_authenticator.h"
  15 #include "third_party/webrtc/libjingle/xmllite/xmlelement.h"
  16
  17 namespace remoting {
  18
  19 namespace {
  20 class PamAuthorizer : public protocol::Authenticator {
  21  public:
  22   PamAuthorizer(scoped_ptr<protocol::Authenticator> underlying);
  23   ~PamAuthorizer() override;
  24
  25   // protocol::Authenticator interface.
  26   State state() const override;
  27   bool started() const override;
  28   RejectionReason rejection_reason() const override;
  29   void ProcessMessage(const buzz::XmlElement* message,
  30                       const base::Closure& resume_callback) override;
  31   scoped_ptr<buzz::XmlElement> GetNextMessage() override;
  32   scoped_ptr<protocol::ChannelAuthenticator> CreateChannelAuthenticator()
  33       const override;
  34
  35  private:
  36   void MaybeCheckLocalLogin();
  37   bool IsLocalLoginAllowed();
  38   void OnMessageProcessed(const base::Closure& resume_callback);
  39
  40   static int PamConversation(int num_messages,
  41                              const struct pam_message** messages,
  42                              struct pam_response** responses,
  43                              void* context);
  44
  45   scoped_ptr<protocol::Authenticator> underlying_;
  46   enum { NOT_CHECKED, ALLOWED, DISALLOWED } local_login_status_;
  47 };
  48 }  // namespace
  49
  50 PamAuthorizer::PamAuthorizer(scoped_ptr<protocol::Authenticator> underlying)
  51     : underlying_(underlying.Pass()),
  52       local_login_status_(NOT_CHECKED) {
  53 }
  54
  55 PamAuthorizer::~PamAuthorizer() {
  56 }
  57
  58 protocol::Authenticator::State PamAuthorizer::state() const {
  59   if (local_login_status_ == DISALLOWED) {
  60     return REJECTED;
  61   } else {
  62     return underlying_->state();
  63   }
  64 }
  65
  66 bool PamAuthorizer::started() const {
  67   return underlying_->started();
  68 }
  69
  70 protocol::Authenticator::RejectionReason
  71 PamAuthorizer::rejection_reason() const {
  72   if (local_login_status_ == DISALLOWED) {
  73     return INVALID_CREDENTIALS;
  74   } else {
  75     return underlying_->rejection_reason();
  76   }
  77 }
  78
  79 void PamAuthorizer::ProcessMessage(const buzz::XmlElement* message,
  80                                    const base::Closure& resume_callback) {
  81   // |underlying_| is owned, so Unretained() is safe here.
  82   underlying_->ProcessMessage(message, base::Bind(
  83       &PamAuthorizer::OnMessageProcessed,
  84       base::Unretained(this), resume_callback));
  85 }
  86
  87 void PamAuthorizer::OnMessageProcessed(const base::Closure& resume_callback) {
  88   MaybeCheckLocalLogin();
  89   resume_callback.Run();
  90 }
  91
  92 scoped_ptr<buzz::XmlElement> PamAuthorizer::GetNextMessage() {
  93   scoped_ptr<buzz::XmlElement> result(underlying_->GetNextMessage());
  94   MaybeCheckLocalLogin();
  95   return result.Pass();
  96 }
  97
  98 scoped_ptr<protocol::ChannelAuthenticator>
  99 PamAuthorizer::CreateChannelAuthenticator() const {
 100   return underlying_->CreateChannelAuthenticator();
 101 }
 102
 103 void PamAuthorizer::MaybeCheckLocalLogin() {
 104   if (local_login_status_ == NOT_CHECKED && state() == ACCEPTED) {
 105     local_login_status_ = IsLocalLoginAllowed() ? ALLOWED : DISALLOWED;
 106   }
 107 }
 108
 109 bool PamAuthorizer::IsLocalLoginAllowed() {
 110   std::string username = GetUsername();
 111   if (username.empty()) {
 112     return false;
 113   }
 114   struct pam_conv conv = { PamConversation, nullptr };
 115   pam_handle_t* handle = nullptr;
 116   int result = pam_start("chrome-remote-desktop", username.c_str(),
 117                          &conv, &handle);
 118   if (result == PAM_SUCCESS) {
 119     result = pam_acct_mgmt(handle, 0);
 120   }
 121   pam_end(handle, result);
 122
 123   HOST_LOG << "Local login check for " << username
 124             << (result == PAM_SUCCESS ? " succeeded." : " failed.");
 125
 126   return result == PAM_SUCCESS;
 127 }
 128
 129 int PamAuthorizer::PamConversation(int num_messages,
 130                                    const struct pam_message** messages,
 131                                    struct pam_response** responses,
 132                                    void* context) {
 133   // Assume we're only being asked to log messages, in which case our response
 134   // need to be free()-able zero-initialized memory.
 135   *responses = static_cast<struct pam_response*>(
 136       calloc(num_messages, sizeof(struct pam_response)));
 137
 138   // We don't expect this function to be called. Since we have no easy way
 139   // of returning a response, we consider it to be an error if we're asked
 140   // for one and abort. Informational and error messages are logged.
 141   for (int i = 0; i < num_messages; ++i) {
 142     const struct pam_message* message = messages[i];
 143     switch (message->msg_style) {
 144       case PAM_ERROR_MSG:
 145         LOG(ERROR) << "PAM conversation error message: " << message->msg;
 146         break;
 147       case PAM_TEXT_INFO:
 148         HOST_LOG << "PAM conversation message: " << message->msg;
 149         break;
 150       default:
 151         LOG(FATAL) << "Unexpected PAM conversation response required: "
 152                    << message->msg << "; msg_style = " << message->msg_style;
 153     }
 154   }
 155   return PAM_SUCCESS;
 156 }
 157
 158
 159 PamAuthorizationFactory::PamAuthorizationFactory(
 160     scoped_ptr<protocol::AuthenticatorFactory> underlying)
 161     : underlying_(underlying.Pass()) {
 162 }
 163
 164 PamAuthorizationFactory::~PamAuthorizationFactory() {
 165 }
 166
 167 scoped_ptr<protocol::Authenticator>
 168 PamAuthorizationFactory::CreateAuthenticator(
 169     const std::string& local_jid,
 170     const std::string& remote_jid,
 171     const buzz::XmlElement* first_message) {
 172   scoped_ptr<protocol::Authenticator> authenticator(
 173       underlying_->CreateAuthenticator(local_jid, remote_jid, first_message));
 174   return make_scoped_ptr(new PamAuthorizer(authenticator.Pass()));
 175 }
 176
 177
 178 }  // namespace remoting