SecurityServer/Authorization/privPortClient.cpp

   1 /*
   2  * Copyright (c) 2003 Apple Computer, Inc. All Rights Reserved.
   3  *
   4  * The contents of this file constitute Original Code as defined in and are
   5  * subject to the Apple Public Source License Version 1.2 (the 'License').
   6  * You may not use this file except in compliance with the License. Please obtain
   7  * a copy of the License at http://www.apple.com/publicsource and read it before
   8  * using this file.
   9  *
  10  * This Original Code and all software distributed under the License are
  11  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESS
  12  * OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, INCLUDING WITHOUT
  13  * LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
  14  * PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. Please see the License for the
  15  * specific language governing rights and limitations under the License.
  16  */
  17
  18
  19 //
  20 // privPortClient - Authorization privileged-port binding client side
  21 //
  22 #include <Security/AuthorizationPriv.h>
  23 #include <Security/fdmover.h>
  24 #include <Security/debugging.h>
  25 #include "privPort.h"
  26
  27 using namespace UnixPlusPlus;
  28 using namespace IPPlusPlus;
  29
  30
  31 //
  32 // Where is the trampoline itself?
  33 //
  34 #if !defined(PORTSERVERPATH)
  35 # define PORTSERVERPATH "/System/Library/CoreServices/privportserver" /* fallback */
  36 #endif
  37
  38
  39 //
  40 // Local functions
  41 //
  42 static void startServer();
  43
  44
  45 //
  46 // The official client function. This does all the work
  47 //
  48 OSStatus AuthorizationBindPrivilegedPort(int fileDescriptor,
  49         const struct sockaddr_in *name,
  50         AuthorizationRef authorization,
  51         AuthorizationFlags flags)
  52 {
  53         BEGIN_API
  54         unsigned short port = ntohs(name->sin_port);
  55         secdebug("portserve", "bind request fd=%d port=%d", fileDescriptor, port);
  56
  57         // must request a privileged port (don't check for debug version)
  58 #if defined(NDEBUG)
  59         if (port <= 0 || port >= IPPORT_RESERVED)
  60                 return errAuthorizationBadAddress;
  61 #endif //NEBUG
  62
  63         // no flags recognized so far
  64         if (flags)
  65                 return errAuthorizationInvalidFlags;
  66
  67         // form the request message
  68         Request request;
  69         if (OSStatus err = AuthorizationMakeExternalForm(authorization, &request.authForm))
  70                 return err;
  71         request.requestedName = *name;
  72
  73         // connect to the port server (start it if we must)
  74         UNSockAddress serverAddress(kPrivilegedPortBinder);
  75         FdMover server;
  76         server.open(AF_UNIX, SOCK_STREAM);
  77         try {
  78                 server.connect(serverAddress);
  79         } catch (const UnixError &error) {
  80                 switch (error.error) {
  81                 case ENOENT:                    // not bound
  82                 case ECONNREFUSED:              // was bound, server is dead
  83                         startServer();
  84                         server.connect(serverAddress);
  85                         break;
  86                 default:
  87                         throw;
  88                 }
  89         }
  90
  91         // send request
  92         secdebug("portserve", "sending request");
  93         FdVector fds;
  94         fds.push_back(fileDescriptor);
  95         if (server.send(&request, sizeof(request), fds) != sizeof(request))
  96                 UnixError::throwMe(EIO);
  97
  98         // read reply
  99         secdebug("portserve", "getting reply");
 100         Reply reply;
 101         if (server.read(&reply, sizeof(reply)) != sizeof(reply))
 102                 UnixError::throwMe(EIO);
 103
 104         secdebug("portserve", "server replied %ld", reply.status);
 105         return ntohl(reply.status);
 106
 107         END_API(CSSM)
 108 }
 109
 110
 111 //
 112 // Start the server (fork/exec)
 113 //
 114 static void startServer()
 115 {
 116         const char *serverpath = PORTSERVERPATH;
 117 #if !defined(NDEBUG)
 118         if (const char *override = getenv("PRIVPORTSERVER"))
 119                 serverpath = override;
 120 #endif //!NDEBUG
 121
 122         secdebug("portserve", "starting %s", serverpath);
 123         switch (fork()) {
 124         case -1:
 125                 UnixError::throwMe();
 126         case 0:                 // child
 127                 execl(serverpath, serverpath, NULL);
 128                 secdebug("portserve", "cannot exec %s (errno=%d)", serverpath, errno);
 129                 _exit(1);
 130         default:                // parent
 131                 sleep(1);
 132                 break;
 133         }
 134 }
 135
 136
 137 //
 138 // A pure-C interface helper function for overriding bind(2).
 139 // This obtains the authorization, then calls AuthorizationBindPrivilegedPort
 140 //
 141 int __authorization_bind(int s, const struct sockaddr_in *name)
 142 {
 143     // obtain authorization
 144     AuthorizationItem rights[] = {
 145         { "system.privilege.port.connect", 0, NULL, 0 }
 146     };
 147     AuthorizationRights rightSet =
 148         { sizeof(rights) / sizeof(rights[0]), rights };
 149     AuthorizationRef auth;
 150     if (AuthorizationCreate(&rightSet, NULL,
 151         kAuthorizationFlagInteractionAllowed |
 152         kAuthorizationFlagExtendRights |
 153         kAuthorizationFlagPreAuthorize,
 154         &auth)) {
 155                 errno = EPERM;
 156                 return -1;
 157         }
 158
 159         // bind
 160         OSStatus err = AuthorizationBindPrivilegedPort(s, name, auth, 0);
 161         AuthorizationFree(auth, 0);     // ignore errors
 162
 163         if (err) {
 164                 errno = (err >= errSecErrnoBase && err <= errSecErrnoLimit) ?
 165                         errno = err - errSecErrnoBase :
 166                         EPERM;
 167                 return -1;
 168         }
 169         return 0;
 170 }