SystemConfiguration.fproj/SCDPlugin.c

   1 /*
   2  * Copyright (c) 2001-2004 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 /*
  25  * Modification History
  26  *
  27  * October 12, 2001             Allan Nathanson <ajn@apple.com>
  28  * - initial revision
  29  */
  30
  31 #include <fcntl.h>
  32 #include <paths.h>
  33 #include <pthread.h>
  34 #include <unistd.h>
  35 #include <sysexits.h>
  36 #include <sys/types.h>
  37 #include <sys/ioctl.h>
  38 #include <sys/socket.h>
  39 #include <sys/wait.h>
  40 #include <mach/mach.h>
  41 #include <mach/mach_error.h>
  42
  43 #include <CoreFoundation/CoreFoundation.h>
  44 #include <SystemConfiguration/SCDPlugin.h>
  45
  46
  47
  48 typedef struct childInfo *childInfoRef;
  49
  50 struct childInfo {
  51         pid_t                   pid;
  52         SCDPluginExecCallBack   callout;
  53         void                    *context;
  54         int                     status;
  55         struct rusage           rusage;
  56         childInfoRef            next;
  57 };
  58
  59
  60 /*
  61  * Mach port used to notify runloop when a child process
  62  * has been reaped.
  63  */
  64 static CFMachPortRef    childReaped     = NULL;
  65
  66 /*
  67  * The following dictionaries contain information about child
  68  * processes, reaped processes, and any associated callback
  69  * information.
  70  *
  71  * Important: Access to these dictionaries should only be
  72  *            made when in a SIGCHLD handler (or when the
  73  *            childLock mutex is held *AND* the signal
  74  *            has been blocked).
  75  */
  76 static childInfoRef     activeChildren  = NULL;
  77 static pthread_mutex_t  lock            = PTHREAD_MUTEX_INITIALIZER;
  78
  79
  80 static inline void
  81 blockSignal()
  82 {
  83         sigset_t        mask    = sigmask(SIGCHLD);
  84
  85         // block SIGCHLD
  86         if (sigprocmask(SIG_BLOCK, &mask, NULL) == -1) {
  87                 perror("sigprocmask(SIG_BLOCK)");
  88         }
  89
  90         return;
  91 }
  92
  93
  94 static inline void
  95 unblockSignal()
  96 {
  97         sigset_t        mask    = sigmask(SIGCHLD);
  98
  99         // unblock SIGCHLD
 100         if (sigprocmask(SIG_UNBLOCK, &mask, NULL) == -1) {
 101                 perror("sigprocmask(SIG_UNBLOCK)");
 102         }
 103
 104         return;
 105 }
 106
 107
 108 static void
 109 reaper(int sigraised)
 110 {
 111         mach_msg_empty_send_t   msg;
 112         mach_msg_option_t       options;
 113         kern_return_t           status;
 114
 115         /*
 116          * block additional SIGCHLD's until current children have
 117          * been reaped.
 118          */
 119         blockSignal();
 120
 121         /*
 122          * send message to indicate that at least one child is ready
 123          * to be reaped.
 124          */
 125         msg.header.msgh_bits = MACH_MSGH_BITS(MACH_MSG_TYPE_COPY_SEND, 0);
 126         msg.header.msgh_size = sizeof(msg);
 127         msg.header.msgh_remote_port = CFMachPortGetPort(childReaped);
 128         msg.header.msgh_local_port = MACH_PORT_NULL;
 129         msg.header.msgh_id = 0;
 130         options = MACH_SEND_TIMEOUT;
 131         status = mach_msg(&msg.header,                  /* msg */
 132                           MACH_SEND_MSG|options,        /* options */
 133                           msg.header.msgh_size,         /* send_size */
 134                           0,                            /* rcv_size */
 135                           MACH_PORT_NULL,               /* rcv_name */
 136                           0,                            /* timeout */
 137                           MACH_PORT_NULL);              /* notify */
 138         if (status == MACH_SEND_TIMED_OUT) {
 139                 mach_msg_destroy(&msg.header);
 140         }
 141
 142         return;
 143 }
 144
 145
 146 static void
 147 childrenReaped(CFMachPortRef port, void *msg, CFIndex size, void *info)
 148 {
 149         pid_t           pid             = 0;
 150         childInfoRef    reapedChildren  = NULL;
 151
 152         do {
 153                 struct rusage   rusage;
 154                 int             status;
 155
 156                 pid = wait4(-1, &status, WNOHANG, &rusage);
 157                 switch (pid) {
 158                         case -1 :       // if error
 159                                 if (errno != ECHILD) {
 160                                         perror("wait4");
 161                                 }
 162                                 break;
 163
 164                         case  0 :       // if no more children
 165                                 break;
 166
 167                         default : {
 168                                 childInfoRef    last;
 169                                 childInfoRef    this;
 170
 171                                 // grab the activeChildren mutex
 172                                 pthread_mutex_lock(&lock);
 173
 174                                 last = NULL;
 175                                 this = activeChildren;
 176                                 while (this) {
 177                                         if (this->pid == pid) {
 178                                                 /* save exit status & usage */
 179                                                 this->status = status;
 180                                                 this->rusage = rusage;
 181
 182                                                 /* remove from activeChildren */
 183                                                 if (last) {
 184                                                         last->next = this->next;
 185                                                 } else {
 186                                                         activeChildren = this->next;
 187                                                 }
 188
 189                                                 /* add to reapedChildren */
 190                                                 this->next = reapedChildren;
 191                                                 reapedChildren = this;
 192
 193                                                 break;
 194                                         } else {
 195                                                 /* if not this child */
 196                                                 last = this;
 197                                                 this = this->next;
 198                                         }
 199                                 }
 200
 201                                 // release the activeChildren mutex
 202                                 pthread_mutex_unlock(&lock);
 203
 204                                 break;
 205                         }
 206                 }
 207         } while (pid > 0);
 208
 209         /*
 210          * we need to know about any new children waiting to be reaped so
 211          * re-enable the SIGCHLD handler.
 212
 213          */
 214         unblockSignal();
 215
 216         while (reapedChildren) {
 217                 childInfoRef    child = reapedChildren;
 218
 219                 reapedChildren = reapedChildren->next;
 220                 (*child->callout)(child->pid,
 221                                   child->status,
 222                                   &child->rusage,
 223                                   child->context);
 224                 CFAllocatorDeallocate(NULL, child);
 225         }
 226
 227         return;
 228 }
 229
 230
 231 void
 232 _SCDPluginExecInit()
 233 {
 234         struct sigaction        act;
 235         CFRunLoopSourceRef      rls;
 236
 237         // create the "a child has been reaped" notification port
 238         childReaped = CFMachPortCreate(NULL, childrenReaped, NULL, NULL);
 239
 240         // set queue limit
 241         {
 242                 mach_port_limits_t      limits;
 243                 kern_return_t           status;
 244
 245                 limits.mpl_qlimit = 1;
 246                 status = mach_port_set_attributes(mach_task_self(),
 247                                                   CFMachPortGetPort(childReaped),
 248                                                   MACH_PORT_LIMITS_INFO,
 249                                                   (mach_port_info_t)&limits,
 250                                                   MACH_PORT_LIMITS_INFO_COUNT);
 251                 if (status != KERN_SUCCESS) {
 252                         perror("mach_port_set_attributes");
 253                 }
 254         }
 255
 256         // add to our runloop
 257         rls = CFMachPortCreateRunLoopSource(NULL, childReaped, 0);
 258         CFRunLoopAddSource(CFRunLoopGetCurrent(), rls, kCFRunLoopDefaultMode);
 259         CFRelease(rls);
 260
 261         // enable signal handler
 262         act.sa_handler = reaper;
 263         sigemptyset(&act.sa_mask);
 264         act.sa_flags = SA_RESTART|SA_NOCLDSTOP;
 265         if (sigaction(SIGCHLD, &act, NULL) == -1) {
 266                 perror("sigaction");
 267         }
 268
 269         return;
 270 }
 271
 272
 273 pid_t
 274 _SCDPluginExecCommand2(SCDPluginExecCallBack    callout,
 275                        void                     *context,
 276                        uid_t                    uid,
 277                        gid_t                    gid,
 278                        const char               *path,
 279                        char * const             argv[],
 280                        SCDPluginExecSetup       setup,
 281                        void                     *setupContext
 282                        )
 283 {
 284         pid_t   pid;
 285
 286         // grab the activeChildren mutex
 287         pthread_mutex_lock(&lock);
 288
 289         pid = fork();
 290
 291         switch (pid) {
 292                 case -1 : {     /* if error */
 293
 294                         int     status;
 295
 296                         status = errno;
 297                         printf("fork() failed: %s\n", strerror(status));
 298                         errno  = status;
 299                         break;
 300                 }
 301
 302                 case 0 : {      /* if child */
 303
 304                         int     i;
 305                         int     status;
 306
 307                         if (setup) {
 308                                 (setup)(pid, setupContext);
 309                         } else {
 310                                 /* close any open FDs */
 311                                 for (i = getdtablesize()-1; i>=0; i--) close(i);
 312                                 open(_PATH_DEVNULL, O_RDWR, 0);
 313                                 dup(0);
 314                                 dup(0);
 315                         }
 316
 317                         if (gid != getegid()) {
 318                                 (void) setgid(gid);
 319                         }
 320
 321                         if (uid != geteuid()) {
 322                                 (void) setuid(uid);
 323                         }
 324
 325                         /* ensure that our PATH environment variable is somewhat reasonable */
 326                         if (setenv("PATH", "/bin:/sbin:/usr/bin:/usr/sbin", 0) == -1) {
 327                                 printf("setenv() failed: %s\n", strerror(errno));
 328                                 exit(EX_OSERR);
 329                         }
 330
 331                         /* execute requested command */
 332                         (void) execv(path, argv);
 333
 334                         /* if the execv failed */
 335                         status = W_EXITCODE(errno, 0);
 336                         _exit (WEXITSTATUS(status));
 337                 }
 338
 339                 default : {     /* if parent */
 340                         if (setup) {
 341                                 (setup)(pid, setupContext);
 342                         }
 343
 344                         if (callout) {
 345                                 childInfoRef    child;
 346
 347                                 // create child process info
 348                                 child = CFAllocatorAllocate(NULL, sizeof(struct childInfo), 0);
 349                                 bzero(child, sizeof(struct childInfo));
 350                                 child->pid     = pid;
 351                                 child->callout = callout;
 352                                 child->context = context;
 353
 354                                 // add the new child to the activeChildren list
 355                                 child->next = activeChildren;
 356                                 activeChildren = child;
 357                         }
 358                         break;
 359                 }
 360         }
 361
 362         // release the activeChildren mutex
 363         pthread_mutex_unlock(&lock);
 364
 365         return pid;
 366 }
 367
 368
 369 pid_t
 370 _SCDPluginExecCommand(SCDPluginExecCallBack     callout,
 371                      void                       *context,
 372                      uid_t                      uid,
 373                      gid_t                      gid,
 374                      const char                 *path,
 375                      char * const               argv[])
 376 {
 377         return _SCDPluginExecCommand2(callout, context, uid, gid, path, argv, NULL, NULL);
 378 }