securityd/src/session.cpp

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  23
  24
  25 //
  26 // session - authentication session domains
  27 //
  28 // Security sessions are now by definition congruent to audit subsystem sessions.
  29 // We represent these sessions within securityd as subclasses of class Session,
  30 // but we reach for the kernel's data whenever we're not sure if our data is
  31 // up to date.
  32 //
  33 // Modifications to session state are made from client space using system calls.
  34 // We discover them when we see changes in audit records as they come in with
  35 // new requests. We cannot use system notifications for such changes because
  36 // securityd is fully symmetrically multi-threaded, and thus may process new
  37 // requests from clients before it gets those notifications.
  38 //
  39 #include <pwd.h>
  40 #include <signal.h>                     // SIGTERM
  41 #include <Security/AuthorizationPriv.h> // kAuthorizationFlagLeastPrivileged
  42 #include "session.h"
  43 #include "connection.h"
  44 #include "database.h"
  45 #include "server.h"
  46 #include <security_utilities/logging.h>
  47 #include <agentquery.h>
  48
  49 using namespace CommonCriteria;
  50
  51
  52 //
  53 // The static session map
  54 //
  55 Session::SessionMap Session::mSessions;
  56 Mutex Session::mSessionLock(Mutex::recursive);
  57
  58
  59 const char Session::kUsername[] = "username";
  60 const char Session::kRealname[] = "realname";
  61
  62
  63 //
  64 // Create a Session object from initial parameters (create)
  65 //
  66 Session::Session(const AuditInfo &audit, Server &server)
  67         : mAudit(audit), mSecurityAgent(NULL), mKeybagState(0)
  68 {
  69         // link to Server as the global nexus in the object mesh
  70         parent(server);
  71
  72         // self-register
  73         StLock<Mutex> _(mSessionLock);
  74         assert(!mSessions[audit.sessionId()]);
  75         mSessions[audit.sessionId()] = this;
  76
  77         // log it
  78     secnotice("SS", "%p Session %d created, uid:%d sessionId:%d", this, this->sessionId(), mAudit.uid(), mAudit.sessionId());
  79         Syslog::notice("Session %d created", this->sessionId());
  80 }
  81
  82
  83 //
  84 // Destroy a Session
  85 //
  86 Session::~Session()
  87 {
  88     secnotice("SS", "%p Session %d destroyed", this, this->sessionId());
  89         Syslog::notice("Session %d destroyed", this->sessionId());
  90 }
  91
  92
  93 Server &Session::server() const
  94 {
  95         return parent<Server>();
  96 }
  97
  98
  99 //
 100 // Locate a session object by session identifier
 101 //
 102 Session &Session::find(pid_t id, bool create)
 103 {
 104         if (id == callerSecuritySession)
 105                 return Server::session();
 106         StLock<Mutex> _(mSessionLock);
 107         SessionMap::iterator it = mSessions.find(id);
 108         if (it != mSessions.end())
 109                 return *it->second;
 110
 111         // new session
 112         if (!create)
 113                 CssmError::throwMe(errSessionInvalidId);
 114         AuditInfo info;
 115         info.get(id);
 116         assert(info.sessionId() == id);
 117         RefPointer<Session> session = new Session(info, Server::active());
 118         mSessions.insert(make_pair(id, session));
 119         return *session;
 120 }
 121
 122
 123 //
 124 // Act on a death notification for a session's underlying audit session object.
 125 // We may not destroy the Session outright here (due to processes that use it),
 126 // but we do clear out its accumulated wealth.
 127 // Note that we may get spurious death notifications for audit sessions that we
 128 // never learned about. Ignore those.
 129 //
 130 void Session::destroy(SessionId id)
 131 {
 132     // remove session from session map
 133     RefPointer<Session> session = NULL;
 134     {
 135         StLock<Mutex> _(mSessionLock);
 136         SessionMap::iterator it = mSessions.find(id);
 137         if (it != mSessions.end()) {
 138             session = it->second;
 139             assert(session->sessionId() == id);
 140             mSessions.erase(it);
 141         }
 142     }
 143
 144     if (session.get()) {
 145         session->kill();
 146     }
 147 }
 148
 149
 150 void Session::kill()
 151 {
 152     StLock<Mutex> _(*this);     // do we need to take this so early?
 153     secnotice("SS", "%p killing session %d", this, this->sessionId());
 154     invalidateSessionAuthHosts();
 155
 156         // base kill processing
 157         PerSession::kill();
 158 }
 159
 160
 161 //
 162 // Refetch audit session data for the current audit session (to catch outside updates
 163 // to the audit record). This is the price we're paying for not requiring an IPC to
 164 // securityd when audit session data changes (this is desirable for delayering the
 165 // software layer cake).
 166 // If we ever disallow changes to (parts of the) audit session record in the kernel,
 167 // we can loosen up on this continual re-fetching.
 168 //
 169 void Session::updateAudit() const
 170 {
 171     CommonCriteria::AuditInfo info;
 172     try {
 173         info.get(mAudit.sessionId());
 174     } catch (...) {
 175         return;
 176     }
 177     mAudit = info;
 178 }
 179
 180 void Session::verifyKeyStorePassphrase(int32_t retries)
 181 {
 182     QueryKeybagPassphrase keybagQuery(*this, retries);
 183     keybagQuery.inferHints(Server::process());
 184     if (keybagQuery.query() != SecurityAgent::noReason) {
 185         CssmError::throwMe(CSSM_ERRCODE_OPERATION_AUTH_DENIED);
 186     }
 187 }
 188
 189 void Session::changeKeyStorePassphrase()
 190 {
 191     service_context_t context = get_current_service_context();
 192     QueryKeybagNewPassphrase keybagQuery(*this);
 193     keybagQuery.inferHints(Server::process());
 194     CssmAutoData pass(Allocator::standard(Allocator::sensitive));
 195     CssmAutoData oldPass(Allocator::standard(Allocator::sensitive));
 196     SecurityAgent::Reason queryReason = keybagQuery.query(oldPass, pass);
 197     if (queryReason == SecurityAgent::noReason) {
 198         service_client_kb_change_secret(&context, oldPass.data(), (int)oldPass.length(), pass.data(), (int)pass.length());
 199     } else {
 200         CssmError::throwMe(CSSM_ERRCODE_OPERATION_AUTH_DENIED);
 201     }
 202 }
 203
 204 void Session::resetKeyStorePassphrase(const CssmData &passphrase)
 205 {
 206     service_context_t context = get_current_service_context();
 207     service_client_kb_reset(&context, passphrase.data(), (int)passphrase.length());
 208 }
 209
 210 service_context_t Session::get_current_service_context()
 211 {
 212     service_context_t context = { sessionId(), originatorUid(), *Server::connection().auditToken() };
 213     return context;
 214 }
 215
 216 void Session::keybagClearState(int state)
 217 {
 218     mKeybagState &= ~state;
 219 }
 220
 221 void Session::keybagSetState(int state)
 222 {
 223     mKeybagState |= state;
 224 }
 225
 226 bool Session::keybagGetState(int state)
 227 {
 228     return mKeybagState & state;
 229 }
 230
 231
 232 //
 233 // Manage authorization client processes
 234 //
 235 void Session::invalidateSessionAuthHosts()
 236 {
 237     StLock<Mutex> _(mAuthHostLock);
 238
 239     // if you got here, we don't care about pending operations: the auth hosts die
 240     Syslog::warning("Killing auth hosts");
 241     if (mSecurityAgent) mSecurityAgent->UnixPlusPlus::Child::kill(SIGTERM);
 242     mSecurityAgent = NULL;
 243 }
 244
 245 void Session::invalidateAuthHosts()
 246 {
 247         StLock<Mutex> _(mSessionLock);
 248         for (SessionMap::const_iterator it = mSessions.begin(); it != mSessions.end(); it++)
 249         it->second->invalidateSessionAuthHosts();
 250 }
 251
 252 //
 253 // On system sleep, call sleepProcessing on all DbCommons of all Sessions
 254 //
 255 void Session::processSystemSleep()
 256 {
 257     SecurityAgentXPCQuery::killAllXPCClients();
 258
 259         StLock<Mutex> _(mSessionLock);
 260         for (SessionMap::const_iterator it = mSessions.begin(); it != mSessions.end(); it++)
 261                 it->second->allReferences(&DbCommon::sleepProcessing);
 262 }
 263
 264
 265 //
 266 // On "lockAll", call sleepProcessing on all DbCommons of this session (only)
 267 //
 268 void Session::processLockAll()
 269 {
 270         allReferences(&DbCommon::lockProcessing);
 271 }
 272
 273
 274 //
 275 // The root session corresponds to the audit session that security is running in.
 276 // This is usually the initial system session; but in debug scenarios it may be
 277 // an "ordinary" graphic login session. In such a debug case, we may add attribute
 278 // flags to the session to make our (debugging) life easier.
 279 //
 280 RootSession::RootSession(uint64_t attributes, Server &server)
 281         : Session(AuditInfo::current(), server)
 282 {
 283         ref();                          // eternalize
 284         mAudit.ai_flags |= attributes;          // merge imposed attributes
 285 }
 286
 287
 288 //
 289 // Accessor method for setting audit session flags.
 290 //
 291 void Session::setAttributes(SessionAttributeBits bits)
 292 {
 293         StLock<Mutex> _(*this);
 294         updateAudit();
 295 //      assert((bits & ~settableAttributes) == 0);
 296         mAudit.ai_flags = bits;
 297         mAudit.set();
 298 }
 299
 300 //
 301 // The default session setup operation always fails.
 302 // Subclasses can override this to support session setup calls.
 303 //
 304 void Session::setupAttributes(SessionCreationFlags flags, SessionAttributeBits attrs)
 305 {
 306         MacOSError::throwMe(errSessionAuthorizationDenied);
 307 }
 308
 309 uid_t Session::originatorUid()
 310 {
 311     if (mAudit.uid() == AU_DEFAUDITID) {
 312         StLock<Mutex> _(*this);
 313         updateAudit();
 314     }
 315     return mAudit.uid();
 316 }
 317
 318
 319 RefPointer<AuthHostInstance>
 320 Session::authhost(const bool restart)
 321 {
 322         StLock<Mutex> _(mAuthHostLock);
 323
 324         if (restart || !mSecurityAgent || (mSecurityAgent->state() != Security::UnixPlusPlus::Child::alive))
 325         {
 326                 if (mSecurityAgent)
 327                         PerSession::kill(*mSecurityAgent);
 328                 mSecurityAgent = new AuthHostInstance(*this);
 329         }
 330         return mSecurityAgent;
 331 }
 332
 333
 334 //
 335 // Debug dumping
 336 //
 337 #if defined(DEBUGDUMP)
 338
 339 void Session::dumpNode()
 340 {
 341         PerSession::dumpNode();
 342         Debug::dump(" auid=%d attrs=%#x securityagent=%p",
 343                 this->sessionId(), uint32_t(this->attributes()), mSecurityAgent);
 344 }
 345
 346 #endif //DEBUGDUMP