bsd/kern/mach_process.c

   1 /*
   2  * Copyright (c) 2000-2006 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_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. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28 /* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */
  29 /*-
  30  * Copyright (c) 1982, 1986, 1989, 1993
  31  *      The Regents of the University of California.  All rights reserved.
  32  * (c) UNIX System Laboratories, Inc.
  33  * All or some portions of this file are derived from material licensed
  34  * to the University of California by American Telephone and Telegraph
  35  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
  36  * the permission of UNIX System Laboratories, Inc.
  37  *
  38  * Redistribution and use in source and binary forms, with or without
  39  * modification, are permitted provided that the following conditions
  40  * are met:
  41  * 1. Redistributions of source code must retain the above copyright
  42  *    notice, this list of conditions and the following disclaimer.
  43  * 2. Redistributions in binary form must reproduce the above copyright
  44  *    notice, this list of conditions and the following disclaimer in the
  45  *    documentation and/or other materials provided with the distribution.
  46  * 3. All advertising materials mentioning features or use of this software
  47  *    must display the following acknowledgement:
  48  *      This product includes software developed by the University of
  49  *      California, Berkeley and its contributors.
  50  * 4. Neither the name of the University nor the names of its contributors
  51  *    may be used to endorse or promote products derived from this software
  52  *    without specific prior written permission.
  53  *
  54  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  55  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  56  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  57  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  58  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  59  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  60  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  61  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  62  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  63  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  64  * SUCH DAMAGE.
  65  *
  66  *      from: @(#)sys_process.c 8.1 (Berkeley) 6/10/93
  67  */
  68
  69 #include <machine/reg.h>
  70 #include <machine/psl.h>
  71
  72 #include <sys/param.h>
  73 #include <sys/systm.h>
  74 #include <sys/proc_internal.h>
  75 #include <sys/kauth.h>
  76 #include <sys/errno.h>
  77 #include <sys/ptrace.h>
  78 #include <sys/uio.h>
  79 #include <sys/user.h>
  80 #include <sys/sysctl.h>
  81 #include <sys/wait.h>
  82
  83 #include <sys/mount_internal.h>
  84 #include <sys/sysproto.h>
  85 #include <sys/kdebug.h>
  86 #include <sys/codesign.h>               /* cs_allow_invalid() */
  87
  88 #include <security/audit/audit.h>
  89
  90 #include <kern/task.h>
  91 #include <kern/thread.h>
  92
  93 #include <mach/task.h>                  /* for task_resume() */
  94 #include <kern/sched_prim.h>            /* for thread_exception_return() */
  95
  96 #include <pexpert/pexpert.h>
  97
  98 /* XXX ken/bsd_kern.c - prototype should be in common header */
  99 int get_task_userstop(task_t);
 100
 101 /* Macros to clear/set/test flags. */
 102 #define SET(t, f)       (t) |= (f)
 103 #define CLR(t, f)       (t) &= ~(f)
 104 #define ISSET(t, f)     ((t) & (f))
 105
 106 extern thread_t port_name_to_thread(mach_port_name_t port_name);
 107 extern thread_t get_firstthread(task_t);
 108
 109
 110 /*
 111  * sys-trace system call.
 112  */
 113
 114 int
 115 ptrace(struct proc *p, struct ptrace_args *uap, int32_t *retval)
 116 {
 117         struct proc *t = current_proc();        /* target process */
 118         task_t          task;
 119         thread_t        th_act;
 120         struct uthread  *ut;
 121         int tr_sigexc = 0;
 122         int error = 0;
 123         int stopped = 0;
 124
 125         AUDIT_ARG(cmd, uap->req);
 126         AUDIT_ARG(pid, uap->pid);
 127         AUDIT_ARG(addr, uap->addr);
 128         AUDIT_ARG(value32, uap->data);
 129
 130         if (uap->req == PT_DENY_ATTACH) {
 131                 proc_lock(p);
 132                 if (ISSET(p->p_lflag, P_LTRACED)) {
 133                         proc_unlock(p);
 134                         KERNEL_DEBUG_CONSTANT(BSDDBG_CODE(DBG_BSD_PROC, BSD_PROC_FRCEXIT) | DBG_FUNC_NONE,
 135                                               p->p_pid, W_EXITCODE(ENOTSUP, 0), 4, 0, 0);
 136                         exit1(p, W_EXITCODE(ENOTSUP, 0), retval);
 137
 138                         thread_exception_return();
 139                         /* NOTREACHED */
 140                 }
 141                 SET(p->p_lflag, P_LNOATTACH);
 142                 proc_unlock(p);
 143
 144                 return(0);
 145         }
 146
 147         if (uap->req == PT_FORCEQUOTA) {
 148                 if (kauth_cred_issuser(kauth_cred_get())) {
 149                         OSBitOrAtomic(P_FORCEQUOTA, &t->p_flag);
 150                         return (0);
 151                 } else
 152                         return (EPERM);
 153         }
 154
 155         /*
 156          *      Intercept and deal with "please trace me" request.
 157          */
 158         if (uap->req == PT_TRACE_ME) {
 159 retry_trace_me:;
 160                 proc_t pproc = proc_parent(p);
 161                 if (pproc == NULL)
 162                         return (EINVAL);
 163 #if CONFIG_MACF
 164                 /*
 165                  * NB: Cannot call kauth_authorize_process(..., KAUTH_PROCESS_CANTRACE, ...)
 166                  *     since that assumes the process being checked is the current process
 167                  *     when, in this case, it is the current process's parent.
 168                  *     Most of the other checks in cantrace() don't apply either.
 169                  */
 170                 if ((error = mac_proc_check_debug(pproc, p)) == 0) {
 171 #endif
 172                         proc_lock(p);
 173                         /* Make sure the process wasn't re-parented. */
 174                         if (p->p_ppid != pproc->p_pid) {
 175                                 proc_unlock(p);
 176                                 proc_rele(pproc);
 177                                 goto retry_trace_me;
 178                         }
 179                         SET(p->p_lflag, P_LTRACED);
 180                         /* Non-attached case, our tracer is our parent. */
 181                         p->p_oppid = p->p_ppid;
 182                         proc_unlock(p);
 183                         /* Child and parent will have to be able to run modified code. */
 184                         cs_allow_invalid(p);
 185                         cs_allow_invalid(pproc);
 186 #if CONFIG_MACF
 187                 }
 188 #endif
 189                 proc_rele(pproc);
 190                 return (error);
 191         }
 192         if (uap->req == PT_SIGEXC) {
 193                 proc_lock(p);
 194                 if (ISSET(p->p_lflag, P_LTRACED)) {
 195                         SET(p->p_lflag, P_LSIGEXC);
 196                         proc_unlock(p);
 197                         return(0);
 198                 } else {
 199                         proc_unlock(p);
 200                         return(EINVAL);
 201                 }
 202         }
 203
 204         /*
 205          * We do not want ptrace to do anything with kernel or launchd
 206          */
 207         if (uap->pid < 2) {
 208                 return(EPERM);
 209         }
 210
 211         /*
 212          *      Locate victim, and make sure it is traceable.
 213          */
 214         if ((t = proc_find(uap->pid)) == NULL)
 215                         return (ESRCH);
 216
 217         AUDIT_ARG(process, t);
 218
 219         task = t->task;
 220         if (uap->req == PT_ATTACHEXC) {
 221 #pragma clang diagnostic push
 222 #pragma clang diagnostic ignored "-Wdeprecated-declarations"
 223                 uap->req = PT_ATTACH;
 224                 tr_sigexc = 1;
 225         }
 226         if (uap->req == PT_ATTACH) {
 227 #pragma clang diagnostic pop
 228                 int             err;
 229
 230
 231                 if ( kauth_authorize_process(proc_ucred(p), KAUTH_PROCESS_CANTRACE,
 232                                                                          t, (uintptr_t)&err, 0, 0) == 0 ) {
 233                         /* it's OK to attach */
 234                         proc_lock(t);
 235                         SET(t->p_lflag, P_LTRACED);
 236                         if (tr_sigexc)
 237                                 SET(t->p_lflag, P_LSIGEXC);
 238
 239                         t->p_oppid = t->p_ppid;
 240                         /* Check whether child and parent are allowed to run modified
 241                          * code (they'll have to) */
 242                         proc_unlock(t);
 243                         cs_allow_invalid(t);
 244                         cs_allow_invalid(p);
 245                         if (t->p_pptr != p)
 246                                 proc_reparentlocked(t, p, 1, 0);
 247
 248                         proc_lock(t);
 249                         if (get_task_userstop(task) > 0 ) {
 250                                 stopped = 1;
 251                         }
 252                         t->p_xstat = 0;
 253                         proc_unlock(t);
 254                         psignal(t, SIGSTOP);
 255                         /*
 256                          * If the process was stopped, wake up and run through
 257                          * issignal() again to properly connect to the tracing
 258                          * process.
 259                          */
 260                         if (stopped)
 261                                 task_resume(task);
 262                         error = 0;
 263                         goto out;
 264                 }
 265                 else {
 266                         /* not allowed to attach, proper error code returned by kauth_authorize_process */
 267                         if (ISSET(t->p_lflag, P_LNOATTACH)) {
 268                                 psignal(p, SIGSEGV);
 269                         }
 270
 271                         error = err;
 272                         goto out;
 273                 }
 274         }
 275
 276         /*
 277          * You can't do what you want to the process if:
 278          *      (1) It's not being traced at all,
 279          */
 280         proc_lock(t);
 281         if (!ISSET(t->p_lflag, P_LTRACED)) {
 282                 proc_unlock(t);
 283                 error = EPERM;
 284                 goto out;
 285         }
 286
 287         /*
 288          *      (2) it's not being traced by _you_, or
 289          */
 290         if (t->p_pptr != p) {
 291                 proc_unlock(t);
 292                 error = EBUSY;
 293                 goto out;
 294         }
 295
 296         /*
 297          *      (3) it's not currently stopped.
 298          */
 299         if (t->p_stat != SSTOP) {
 300                 proc_unlock(t);
 301                 error = EBUSY;
 302                 goto out;
 303         }
 304
 305         /*
 306          *      Mach version of ptrace executes request directly here,
 307          *      thus simplifying the interaction of ptrace and signals.
 308          */
 309         /* proc lock is held here */
 310         switch (uap->req) {
 311
 312         case PT_DETACH:
 313                 if (t->p_oppid != t->p_ppid) {
 314                         struct proc *pp;
 315
 316                         proc_unlock(t);
 317                         pp = proc_find(t->p_oppid);
 318                         if (pp != PROC_NULL) {
 319                                 proc_reparentlocked(t, pp, 1, 0);
 320                                 proc_rele(pp);
 321                         } else {
 322                                 /* original parent exited while traced */
 323                                 proc_list_lock();
 324                                 t->p_listflag |= P_LIST_DEADPARENT;
 325                                 proc_list_unlock();
 326                                 proc_reparentlocked(t, initproc, 1, 0);
 327                         }
 328                         proc_lock(t);
 329                 }
 330
 331                 t->p_oppid = 0;
 332                 CLR(t->p_lflag, P_LTRACED);
 333                 CLR(t->p_lflag, P_LSIGEXC);
 334                 proc_unlock(t);
 335                 goto resume;
 336
 337         case PT_KILL:
 338                 /*
 339                  *      Tell child process to kill itself after it
 340                  *      is resumed by adding NSIG to p_cursig. [see issig]
 341                  */
 342                 proc_unlock(t);
 343 #if CONFIG_MACF
 344                 error = mac_proc_check_signal(p, t, SIGKILL);
 345                 if (0 != error)
 346                         goto resume;
 347 #endif
 348                 psignal(t, SIGKILL);
 349                 goto resume;
 350
 351         case PT_STEP:                   /* single step the child */
 352         case PT_CONTINUE:               /* continue the child */
 353                 proc_unlock(t);
 354                 th_act = (thread_t)get_firstthread(task);
 355                 if (th_act == THREAD_NULL) {
 356                         error = EINVAL;
 357                         goto out;
 358                 }
 359
 360                 /* force use of Mach SPIs (and task_for_pid security checks) to adjust PC */
 361                 if (uap->addr != (user_addr_t)1) {
 362                         error = ENOTSUP;
 363                         goto out;
 364                 }
 365
 366                 if ((unsigned)uap->data >= NSIG) {
 367                         error = EINVAL;
 368                         goto out;
 369                 }
 370
 371                 if (uap->data != 0) {
 372 #if CONFIG_MACF
 373                         error = mac_proc_check_signal(p, t, uap->data);
 374                         if (0 != error)
 375                                 goto out;
 376 #endif
 377                         psignal(t, uap->data);
 378                 }
 379
 380                 if (uap->req == PT_STEP) {
 381                         /*
 382                          * set trace bit
 383                          * we use sending SIGSTOP as a comparable security check.
 384                          */
 385 #if CONFIG_MACF
 386                         error = mac_proc_check_signal(p, t, SIGSTOP);
 387                         if (0 != error) {
 388                                 goto out;
 389                         }
 390 #endif
 391                         if (thread_setsinglestep(th_act, 1) != KERN_SUCCESS) {
 392                                 error = ENOTSUP;
 393                                 goto out;
 394                         }
 395                 } else {
 396                         /*
 397                          * clear trace bit if on
 398                          * we use sending SIGCONT as a comparable security check.
 399                          */
 400 #if CONFIG_MACF
 401                         error = mac_proc_check_signal(p, t, SIGCONT);
 402                         if (0 != error) {
 403                                 goto out;
 404                         }
 405 #endif
 406                         if (thread_setsinglestep(th_act, 0) != KERN_SUCCESS) {
 407                                 error = ENOTSUP;
 408                                 goto out;
 409                         }
 410                 }
 411         resume:
 412                 proc_lock(t);
 413                 t->p_xstat = uap->data;
 414                 t->p_stat = SRUN;
 415                 if (t->sigwait) {
 416                         wakeup((caddr_t)&(t->sigwait));
 417                         proc_unlock(t);
 418                         if ((t->p_lflag & P_LSIGEXC) == 0) {
 419                                 task_resume(task);
 420                         }
 421                 } else
 422                         proc_unlock(t);
 423
 424                 break;
 425
 426         case PT_THUPDATE:  {
 427                 proc_unlock(t);
 428                 if ((unsigned)uap->data >= NSIG) {
 429                         error = EINVAL;
 430                         goto out;
 431                 }
 432                 th_act = port_name_to_thread(CAST_MACH_PORT_TO_NAME(uap->addr));
 433                 if (th_act == THREAD_NULL) {
 434                         error = ESRCH;
 435                         goto out;
 436                 }
 437                 ut = (uthread_t)get_bsdthread_info(th_act);
 438                 if (uap->data)
 439                         ut->uu_siglist |= sigmask(uap->data);
 440                 proc_lock(t);
 441                 t->p_xstat = uap->data;
 442                 t->p_stat = SRUN;
 443                 proc_unlock(t);
 444                 thread_deallocate(th_act);
 445                 error = 0;
 446                 }
 447                 break;
 448         default:
 449                 proc_unlock(t);
 450                 error = EINVAL;
 451                 goto out;
 452         }
 453
 454         error = 0;
 455 out:
 456         proc_rele(t);
 457         return(error);
 458 }
 459
 460
 461 /*
 462  * determine if one process (cur_procp) can trace another process (traced_procp).
 463  */
 464
 465 int
 466 cantrace(proc_t cur_procp, kauth_cred_t creds, proc_t traced_procp, int *errp)
 467 {
 468         int             my_err;
 469         /*
 470          * You can't trace a process if:
 471          *      (1) it's the process that's doing the tracing,
 472          */
 473         if (traced_procp->p_pid == cur_procp->p_pid) {
 474                 *errp = EINVAL;
 475                 return (0);
 476         }
 477
 478         /*
 479          *      (2) it's already being traced, or
 480          */
 481         if (ISSET(traced_procp->p_lflag, P_LTRACED)) {
 482                 *errp = EBUSY;
 483                 return (0);
 484         }
 485
 486         /*
 487          *      (3) it's not owned by you, or is set-id on exec
 488          *          (unless you're root).
 489          */
 490         if ((kauth_cred_getruid(creds) != kauth_cred_getruid(proc_ucred(traced_procp)) ||
 491                 ISSET(traced_procp->p_flag, P_SUGID)) &&
 492                 (my_err = suser(creds, &cur_procp->p_acflag)) != 0) {
 493                 *errp = my_err;
 494                 return (0);
 495         }
 496
 497         if ((cur_procp->p_lflag & P_LTRACED) && isinferior(cur_procp, traced_procp)) {
 498                 *errp = EPERM;
 499                 return (0);
 500         }
 501
 502         if (ISSET(traced_procp->p_lflag, P_LNOATTACH)) {
 503                 *errp = EBUSY;
 504                 return (0);
 505         }
 506
 507 #if CONFIG_MACF
 508         if ((my_err = mac_proc_check_debug(cur_procp, traced_procp)) != 0) {
 509                 *errp = my_err;
 510                 return (0);
 511         }
 512 #endif
 513
 514         return(1);
 515 }