SystemConfiguration.fproj/SCDPlugin.c

   1 /*
   2  * Copyright (c) 2001-2003 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
 139         return;
 140 }
 141
 142
 143 static void
 144 childrenReaped(CFMachPortRef port, void *msg, CFIndex size, void *info)
 145 {
 146         pid_t           pid             = 0;
 147         childInfoRef    reapedChildren  = NULL;
 148
 149         do {
 150                 struct rusage   rusage;
 151                 int             status;
 152
 153                 pid = wait4(-1, &status, WNOHANG, &rusage);
 154                 switch (pid) {
 155                         case -1 :       // if error
 156                                 if (errno != ECHILD) {
 157                                         perror("wait4");
 158                                 }
 159                                 break;
 160
 161                         case  0 :       // if no more children
 162                                 break;
 163
 164                         default : {
 165                                 childInfoRef    last;
 166                                 childInfoRef    this;
 167
 168                                 // grab the activeChildren mutex
 169                                 pthread_mutex_lock(&lock);
 170
 171                                 last = NULL;
 172                                 this = activeChildren;
 173                                 while (this) {
 174                                         if (this->pid == pid) {
 175                                                 /* save exit status & usage */
 176                                                 this->status = status;
 177                                                 this->rusage = rusage;
 178
 179                                                 /* remove from activeChildren */
 180                                                 if (last) {
 181                                                         last->next = this->next;
 182                                                 } else {
 183                                                         activeChildren = this->next;
 184                                                 }
 185
 186                                                 /* add to reapedChildren */
 187                                                 this->next = reapedChildren;
 188                                                 reapedChildren = this;
 189
 190                                                 break;
 191                                         } else {
 192                                                 /* if not this child */
 193                                                 last = this;
 194                                                 this = this->next;
 195                                         }
 196                                 }
 197
 198                                 // release the activeChildren mutex
 199                                 pthread_mutex_unlock(&lock);
 200
 201                                 break;
 202                         }
 203                 }
 204         } while (pid > 0);
 205
 206         /*
 207          * we need to know about any new children waiting to be reaped so
 208          * re-enable the SIGCHLD handler.
 209
 210          */
 211         unblockSignal();
 212
 213         while (reapedChildren) {
 214                 childInfoRef    child = reapedChildren;
 215
 216                 reapedChildren = reapedChildren->next;
 217                 (*child->callout)(child->pid,
 218                                   child->status,
 219                                   &child->rusage,
 220                                   child->context);
 221                 CFAllocatorDeallocate(NULL, child);
 222         }
 223
 224         return;
 225 }
 226
 227
 228 void
 229 _SCDPluginExecInit()
 230 {
 231         struct sigaction        act;
 232         CFRunLoopSourceRef      rls;
 233
 234         // create the "a child has been reaped" notification port
 235         childReaped = CFMachPortCreate(NULL, childrenReaped, NULL, NULL);
 236
 237         // set queue limit
 238         {
 239                 mach_port_limits_t      limits;
 240                 kern_return_t           status;
 241
 242                 limits.mpl_qlimit = 1;
 243                 status = mach_port_set_attributes(mach_task_self(),
 244                                                   CFMachPortGetPort(childReaped),
 245                                                   MACH_PORT_LIMITS_INFO,
 246                                                   (mach_port_info_t)&limits,
 247                                                   MACH_PORT_LIMITS_INFO_COUNT);
 248                 if (status != KERN_SUCCESS) {
 249                         perror("mach_port_set_attributes");
 250                 }
 251         }
 252
 253         // add to our runloop
 254         rls = CFMachPortCreateRunLoopSource(NULL, childReaped, 0);
 255         CFRunLoopAddSource(CFRunLoopGetCurrent(), rls, kCFRunLoopDefaultMode);
 256         CFRelease(rls);
 257
 258         // enable signal handler
 259         act.sa_handler = reaper;
 260         sigemptyset(&act.sa_mask);
 261         act.sa_flags = SA_RESTART|SA_NOCLDSTOP;
 262         if (sigaction(SIGCHLD, &act, NULL) == -1) {
 263                 perror("sigaction");
 264         }
 265
 266         return;
 267 }
 268
 269
 270 pid_t
 271 _SCDPluginExecCommand2(SCDPluginExecCallBack    callout,
 272                        void                     *context,
 273                        uid_t                    uid,
 274                        gid_t                    gid,
 275                        const char               *path,
 276                        char * const             argv[],
 277                        SCDPluginExecSetup       setup,
 278                        void                     *setupContext
 279                        )
 280 {
 281         pid_t   pid;
 282
 283         // grab the activeChildren mutex
 284         pthread_mutex_lock(&lock);
 285
 286         pid = fork();
 287
 288         switch (pid) {
 289                 case -1 : {     /* if error */
 290
 291                         int     status;
 292
 293                         status = errno;
 294                         printf("fork() failed: %s\n", strerror(status));
 295                         errno  = status;
 296                         break;
 297                 }
 298
 299                 case 0 : {      /* if child */
 300
 301                         uid_t   curUID  = geteuid();
 302                         gid_t   curGID  = getegid();
 303                         int     i;
 304                         int     status;
 305
 306                         if (curUID != uid) {
 307                                 (void) setuid(uid);
 308                         }
 309
 310                         if (curGID != gid) {
 311                                 (void) setgid(gid);
 312                         }
 313
 314                         if (setup) {
 315                                 (setup)(pid, setupContext);
 316                         } else {
 317                                 /* close any open FDs */
 318                                 for (i = getdtablesize()-1; i>=0; i--) close(i);
 319                                 open(_PATH_DEVNULL, O_RDWR, 0);
 320                                 dup(0);
 321                                 dup(0);
 322                         }
 323
 324                         /* ensure that our PATH environment variable is somewhat reasonable */
 325                         if (setenv("PATH", "/bin:/sbin:/usr/bin:/usr/sbin", 0) == -1) {
 326                                 printf("setenv() failed: %s\n", strerror(errno));
 327                                 exit(EX_OSERR);
 328                         }
 329
 330                         /* execute requested command */
 331                         (void) execv(path, argv);
 332
 333                         /* if the execv failed */
 334                         status = W_EXITCODE(errno, 0);
 335                         _exit (WEXITSTATUS(status));
 336                 }
 337
 338                 default : {     /* if parent */
 339                         if (setup) {
 340                                 (setup)(pid, setupContext);
 341                         }
 342
 343                         if (callout) {
 344                                 childInfoRef    child;
 345
 346                                 // create child process info
 347                                 child = CFAllocatorAllocate(NULL, sizeof(struct childInfo), 0);
 348                                 bzero(child, sizeof(struct childInfo));
 349                                 child->pid     = pid;
 350                                 child->callout = callout;
 351                                 child->context = context;
 352
 353                                 // add the new child to the activeChildren list
 354                                 child->next = activeChildren;
 355                                 activeChildren = child;
 356                         }
 357                         break;
 358                 }
 359         }
 360
 361         // release the activeChildren mutex
 362         pthread_mutex_unlock(&lock);
 363
 364         return pid;
 365 }
 366
 367
 368 pid_t
 369 _SCDPluginExecCommand(SCDPluginExecCallBack     callout,
 370                      void                       *context,
 371                      uid_t                      uid,
 372                      gid_t                      gid,
 373                      const char                 *path,
 374                      char * const               argv[])
 375 {
 376         return _SCDPluginExecCommand2(callout, context, uid, gid, path, argv, NULL, NULL);
 377 }