SystemConfiguration.fproj/SCDPlugin.c

   1 /*
   2  * Copyright (c) 2001-2003 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25
  26 /*
  27  * Modification History
  28  *
  29  * October 12, 2001             Allan Nathanson <ajn@apple.com>
  30  * - initial revision
  31  */
  32
  33 #include <fcntl.h>
  34 #include <paths.h>
  35 #include <pthread.h>
  36 #include <unistd.h>
  37 #include <sysexits.h>
  38 #include <sys/types.h>
  39 #include <sys/ioctl.h>
  40 #include <sys/socket.h>
  41 #include <sys/wait.h>
  42 #include <mach/mach.h>
  43 #include <mach/mach_error.h>
  44
  45 #include <CoreFoundation/CoreFoundation.h>
  46 #include <SystemConfiguration/SCDPlugin.h>
  47
  48
  49
  50 typedef struct childInfo *childInfoRef;
  51
  52 struct childInfo {
  53         pid_t                   pid;
  54         SCDPluginExecCallBack   callout;
  55         void                    *context;
  56         int                     status;
  57         struct rusage           rusage;
  58         childInfoRef            next;
  59 };
  60
  61
  62 /*
  63  * Mach port used to notify runloop when a child process
  64  * has been reaped.
  65  */
  66 static CFMachPortRef    childReaped     = NULL;
  67
  68 /*
  69  * The following dictionaries contain information about child
  70  * processes, reaped processes, and any associated callback
  71  * information.
  72  *
  73  * Important: Access to these dictionaries should only be
  74  *            made when in a SIGCHLD handler (or when the
  75  *            childLock mutex is held *AND* the signal
  76  *            has been blocked).
  77  */
  78 static childInfoRef     activeChildren  = NULL;
  79 static pthread_mutex_t  lock            = PTHREAD_MUTEX_INITIALIZER;
  80
  81
  82 static inline void
  83 blockSignal()
  84 {
  85         sigset_t        mask    = sigmask(SIGCHLD);
  86
  87         // block SIGCHLD
  88         if (sigprocmask(SIG_BLOCK, &mask, NULL) == -1) {
  89                 perror("sigprocmask(SIG_BLOCK)");
  90         }
  91
  92         return;
  93 }
  94
  95
  96 static inline void
  97 unblockSignal()
  98 {
  99         sigset_t        mask    = sigmask(SIGCHLD);
 100
 101         // unblock SIGCHLD
 102         if (sigprocmask(SIG_UNBLOCK, &mask, NULL) == -1) {
 103                 perror("sigprocmask(SIG_UNBLOCK)");
 104         }
 105
 106         return;
 107 }
 108
 109
 110 static void
 111 reaper(int sigraised)
 112 {
 113         mach_msg_empty_send_t   msg;
 114         mach_msg_option_t       options;
 115         kern_return_t           status;
 116
 117         /*
 118          * block additional SIGCHLD's until current children have
 119          * been reaped.
 120          */
 121         blockSignal();
 122
 123         /*
 124          * send message to indicate that at least one child is ready
 125          * to be reaped.
 126          */
 127         msg.header.msgh_bits = MACH_MSGH_BITS(MACH_MSG_TYPE_COPY_SEND, 0);
 128         msg.header.msgh_size = sizeof(msg);
 129         msg.header.msgh_remote_port = CFMachPortGetPort(childReaped);
 130         msg.header.msgh_local_port = MACH_PORT_NULL;
 131         msg.header.msgh_id = 0;
 132         options = MACH_SEND_TIMEOUT;
 133         status = mach_msg(&msg.header,                  /* msg */
 134                           MACH_SEND_MSG|options,        /* options */
 135                           msg.header.msgh_size,         /* send_size */
 136                           0,                            /* rcv_size */
 137                           MACH_PORT_NULL,               /* rcv_name */
 138                           0,                            /* timeout */
 139                           MACH_PORT_NULL);              /* notify */
 140
 141         return;
 142 }
 143
 144
 145 static void
 146 childrenReaped(CFMachPortRef port, void *msg, CFIndex size, void *info)
 147 {
 148         pid_t           pid             = 0;
 149         childInfoRef    reapedChildren  = NULL;
 150
 151         do {
 152                 struct rusage   rusage;
 153                 int             status;
 154
 155                 pid = wait4(-1, &status, WNOHANG, &rusage);
 156                 switch (pid) {
 157                         case -1 :       // if error
 158                                 if (errno != ECHILD) {
 159                                         perror("wait4");
 160                                 }
 161                                 break;
 162
 163                         case  0 :       // if no more children
 164                                 break;
 165
 166                         default : {
 167                                 childInfoRef    last;
 168                                 childInfoRef    this;
 169
 170                                 // grab the activeChildren mutex
 171                                 pthread_mutex_lock(&lock);
 172
 173                                 last = NULL;
 174                                 this = activeChildren;
 175                                 while (this) {
 176                                         if (this->pid == pid) {
 177                                                 /* save exit status & usage */
 178                                                 this->status = status;
 179                                                 this->rusage = rusage;
 180
 181                                                 /* remove from activeChildren */
 182                                                 if (last) {
 183                                                         last->next = this->next;
 184                                                 } else {
 185                                                         activeChildren = this->next;
 186                                                 }
 187
 188                                                 /* add to reapedChildren */
 189                                                 this->next = reapedChildren;
 190                                                 reapedChildren = this;
 191
 192                                                 break;
 193                                         } else {
 194                                                 /* if not this child */
 195                                                 last = this;
 196                                                 this = this->next;
 197                                         }
 198                                 }
 199
 200                                 // release the activeChildren mutex
 201                                 pthread_mutex_unlock(&lock);
 202
 203                                 break;
 204                         }
 205                 }
 206         } while (pid > 0);
 207
 208         /*
 209          * we need to know about any new children waiting to be reaped so
 210          * re-enable the SIGCHLD handler.
 211
 212          */
 213         unblockSignal();
 214
 215         while (reapedChildren) {
 216                 childInfoRef    child = reapedChildren;
 217
 218                 reapedChildren = reapedChildren->next;
 219                 (*child->callout)(child->pid,
 220                                   child->status,
 221                                   &child->rusage,
 222                                   child->context);
 223                 CFAllocatorDeallocate(NULL, child);
 224         }
 225
 226         return;
 227 }
 228
 229
 230 void
 231 _SCDPluginExecInit()
 232 {
 233         struct sigaction        act;
 234         CFRunLoopSourceRef      rls;
 235
 236         // create the "a child has been reaped" notification port
 237         childReaped = CFMachPortCreate(NULL, childrenReaped, NULL, NULL);
 238
 239         // set queue limit
 240         {
 241                 mach_port_limits_t      limits;
 242                 kern_return_t           status;
 243
 244                 limits.mpl_qlimit = 1;
 245                 status = mach_port_set_attributes(mach_task_self(),
 246                                                   CFMachPortGetPort(childReaped),
 247                                                   MACH_PORT_LIMITS_INFO,
 248                                                   (mach_port_info_t)&limits,
 249                                                   MACH_PORT_LIMITS_INFO_COUNT);
 250                 if (status != KERN_SUCCESS) {
 251                         perror("mach_port_set_attributes");
 252                 }
 253         }
 254
 255         // add to our runloop
 256         rls = CFMachPortCreateRunLoopSource(NULL, childReaped, 0);
 257         CFRunLoopAddSource(CFRunLoopGetCurrent(), rls, kCFRunLoopDefaultMode);
 258         CFRelease(rls);
 259
 260         // enable signal handler
 261         act.sa_handler = reaper;
 262         sigemptyset(&act.sa_mask);
 263         act.sa_flags = SA_RESTART|SA_NOCLDSTOP;
 264         if (sigaction(SIGCHLD, &act, NULL) == -1) {
 265                 perror("sigaction");
 266         }
 267
 268         return;
 269 }
 270
 271
 272 pid_t
 273 _SCDPluginExecCommand2(SCDPluginExecCallBack    callout,
 274                        void                     *context,
 275                        uid_t                    uid,
 276                        gid_t                    gid,
 277                        const char               *path,
 278                        char * const             argv[],
 279                        SCDPluginExecSetup       setup,
 280                        void                     *setupContext
 281                        )
 282 {
 283         pid_t   pid;
 284
 285         // grab the activeChildren mutex
 286         pthread_mutex_lock(&lock);
 287
 288         pid = fork();
 289
 290         switch (pid) {
 291                 case -1 : {     /* if error */
 292
 293                         int     status;
 294
 295                         status = errno;
 296                         printf("fork() failed: %s\n", strerror(status));
 297                         errno  = status;
 298                         break;
 299                 }
 300
 301                 case 0 : {      /* if child */
 302
 303                         uid_t   curUID  = geteuid();
 304                         gid_t   curGID  = getegid();
 305                         int     i;
 306                         int     status;
 307
 308                         if (curUID != uid) {
 309                                 (void) setuid(uid);
 310                         }
 311
 312                         if (curGID != gid) {
 313                                 (void) setgid(gid);
 314                         }
 315
 316                         if (setup) {
 317                                 (setup)(pid, setupContext);
 318                         } else {
 319                                 /* close any open FDs */
 320                                 for (i = getdtablesize()-1; i>=0; i--) close(i);
 321                                 open(_PATH_DEVNULL, O_RDWR, 0);
 322                                 dup(0);
 323                                 dup(0);
 324                         }
 325
 326                         /* ensure that our PATH environment variable is somewhat reasonable */
 327                         if (setenv("PATH", "/bin:/sbin:/usr/bin:/usr/sbin", 0) == -1) {
 328                                 printf("setenv() failed: %s\n", strerror(errno));
 329                                 exit(EX_OSERR);
 330                         }
 331
 332                         /* execute requested command */
 333                         (void) execv(path, argv);
 334
 335                         /* if the execv failed */
 336                         status = W_EXITCODE(errno, 0);
 337                         _exit (WEXITSTATUS(status));
 338                 }
 339
 340                 default : {     /* if parent */
 341                         if (setup) {
 342                                 (setup)(pid, setupContext);
 343                         }
 344
 345                         if (callout) {
 346                                 childInfoRef    child;
 347
 348                                 // create child process info
 349                                 child = CFAllocatorAllocate(NULL, sizeof(struct childInfo), 0);
 350                                 bzero(child, sizeof(struct childInfo));
 351                                 child->pid     = pid;
 352                                 child->callout = callout;
 353                                 child->context = context;
 354
 355                                 // add the new child to the activeChildren list
 356                                 child->next = activeChildren;
 357                                 activeChildren = child;
 358                         }
 359                         break;
 360                 }
 361         }
 362
 363         // release the activeChildren mutex
 364         pthread_mutex_unlock(&lock);
 365
 366         return pid;
 367 }
 368
 369
 370 pid_t
 371 _SCDPluginExecCommand(SCDPluginExecCallBack     callout,
 372                      void                       *context,
 373                      uid_t                      uid,
 374                      gid_t                      gid,
 375                      const char                 *path,
 376                      char * const               argv[])
 377 {
 378         return _SCDPluginExecCommand2(callout, context, uid, gid, path, argv, NULL, NULL);
 379 }