src/authhost.cpp

   1 /*
   2  * Copyright (c) 2000-2004 Apple Computer, Inc. All Rights Reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23
  24 #include <paths.h>
  25 #include <fcntl.h>
  26 #include "authhost.h"
  27 #include "server.h"
  28
  29 #include <grp.h>
  30 #include <pwd.h>
  31 #include <sys/types.h>
  32 #include <sys/sysctl.h>
  33 #include <syslog.h>
  34 #include <pthread.h>
  35
  36 static pthread_once_t agent_cred_init = PTHREAD_ONCE_INIT;
  37 static gid_t agent_gid = 92;
  38 static uid_t agent_uid = 92;
  39
  40 void initialize_agent_creds()
  41 {
  42     struct passwd *agentUser = getpwnam("securityagent");
  43     if (agentUser)
  44     {
  45         agent_uid = agentUser->pw_uid;
  46         agent_gid = agentUser->pw_gid;
  47         endpwent();
  48     }
  49 }
  50
  51 AuthHostInstance::AuthHostInstance(Session &session, AuthHostType host) :
  52         mHostType(host)
  53 {
  54         secdebug("authhost", "authhost born (%p)", this);
  55         referent(session);
  56         session.addReference(*this);
  57     if (host == securityAgent)
  58         pthread_once(&agent_cred_init, initialize_agent_creds);
  59 }
  60
  61 AuthHostInstance::~AuthHostInstance()
  62 {
  63         secdebug("authhost", "authhost died (%p)", this);
  64 }
  65
  66 Session &AuthHostInstance::session() const
  67 {
  68         return referent<Session>();
  69 }
  70
  71 void
  72 AuthHostInstance::childAction()
  73 {
  74         // Setup the environment for the SecurityAgent
  75         unsetenv("USER");
  76         unsetenv("LOGNAME");
  77         unsetenv("HOME");
  78
  79         // close down any files that might have been open at this point
  80         int maxDescriptors = getdtablesize ();
  81         int i;
  82
  83         int devnull = open(_PATH_DEVNULL, O_RDWR, 0);
  84         if (devnull >= 0) for (i = 0; i < 3; ++i)
  85         {
  86                 dup2(devnull, i);
  87         }
  88
  89         for (i = 3; i < maxDescriptors; ++i)
  90         {
  91                 close (i);
  92         }
  93
  94         // construct path to SecurityAgent
  95         char agentExecutable[PATH_MAX + 1];
  96         const char *path = getenv("SECURITYAGENT");
  97         if (!path)
  98                 path = "/System/Library/CoreServices/SecurityAgent.app";
  99
 100         if ((mHostType == userAuthHost) || (mHostType == privilegedAuthHost))
 101         {
 102                 snprintf(agentExecutable, sizeof(agentExecutable), "%s/Contents/Resources/authorizationhost", path);
 103                 secdebug("AuthHostInstance", "execl(%s)", agentExecutable);
 104                 execl(agentExecutable, agentExecutable, NULL);
 105         }
 106         else
 107         {
 108                 snprintf(agentExecutable, sizeof(agentExecutable), "%s/Contents/MacOS/SecurityAgent", path);
 109
 110                 pid_t pid = getpid();
 111                 if ((pid <= 0) ||
 112             sysctlbyname("vfs.generic.noremotehang", NULL, NULL, &pid, sizeof(pid)))
 113                                 syslog(LOG_ERR, "Failed to set vfs.generic.noremotehang for pid(%d)", pid);
 114
 115                 setgroups(1, &agent_gid);
 116                 setgid(agent_gid);
 117                 setuid(agent_uid);
 118
 119                 CFRef<CFDataRef> userPrefs(session().copyUserPrefs());
 120
 121                 FILE *mbox = tmpfile();
 122
 123                 if (userPrefs && mbox)
 124                 {
 125                         if (fwrite(CFDataGetBytePtr(userPrefs), CFDataGetLength(userPrefs), 1, mbox) != 1)
 126                                 fclose(mbox);
 127                         else
 128                         {
 129                                 char mboxFdString[20];
 130                                 fflush(mbox);
 131                                 if ((int)sizeof(mboxFdString) > snprintf(mboxFdString, sizeof(mboxFdString), "%d", fileno(mbox)))
 132                                         setenv("SECURITYAGENT_USERPREFS_FD", mboxFdString, 1);
 133                         }
 134                 }
 135
 136                 secdebug("AuthHostInstance", "execl(%s) as user (%d,%d)", agentExecutable, agent_uid, agent_gid);
 137                 execl(agentExecutable, agentExecutable, NULL);
 138         }
 139
 140         secdebug("AuthHostInstance", "execl failed, errno=%d", errno);
 141         // Unconditional suicide follows.
 142         // See comments below on why we can't use abort()
 143 #if 1
 144         _exit(1);
 145 #else
 146         // NOTE: OS X abort() is implemented as kill(getuid()), which fails
 147         // for a setuid-root process that has setuid'd. Go back to root to die...
 148         setuid(0);
 149         abort();
 150 #endif
 151 }
 152
 153 Port
 154 AuthHostInstance::activate()
 155 {
 156         StLock<Mutex> _(*this);
 157         if (state() != alive)
 158         {
 159                 if ((mHostType == securityAgent) &&
 160                     !(session().attributes() & sessionHasGraphicAccess))
 161                         CssmError::throwMe(CSSM_ERRCODE_NO_USER_INTERACTION);
 162
 163                 Security::MachPlusPlus::StBootstrap bootSaver(session().bootstrapPort());
 164
 165                 fork();
 166                 switch (ServerChild::state()) {
 167                 case Child::alive:
 168                         secdebug("AuthHostInstance", "%p (pid %d) has launched", this, pid());
 169                         break;
 170                 case Child::dead:
 171                         secdebug("AuthHostInstance", "%p (pid %d) failed on startup", this, pid());
 172                         break;
 173                 default:
 174                         assert(false);
 175                 }
 176         }
 177
 178         if (!ready())
 179                 CssmError::throwMe(CSSM_ERRCODE_NO_USER_INTERACTION);
 180
 181         return servicePort();
 182 }