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 #if CONFIG_MACF
  99 #include <security/mac_framework.h>
 100 #endif
 101
 102 /* XXX ken/bsd_kern.c - prototype should be in common header */
 103 int get_task_userstop(task_t);
 104
 105 /* Macros to clear/set/test flags. */
 106 #define SET(t, f)       (t) |= (f)
 107 #define CLR(t, f)       (t) &= ~(f)
 108 #define ISSET(t, f)     ((t) & (f))
 109
 110 extern thread_t port_name_to_thread(mach_port_name_t port_name);
 111 extern thread_t get_firstthread(task_t);
 112
 113
 114 /*
 115  * sys-trace system call.
 116  */
 117
 118 int
 119 ptrace(struct proc *p, struct ptrace_args *uap, int32_t *retval)
 120 {
 121         struct proc *t = current_proc();        /* target process */
 122         task_t          task;
 123         thread_t        th_act;
 124         struct uthread  *ut;
 125         int tr_sigexc = 0;
 126         int error = 0;
 127         int stopped = 0;
 128
 129         AUDIT_ARG(cmd, uap->req);
 130         AUDIT_ARG(pid, uap->pid);
 131         AUDIT_ARG(addr, uap->addr);
 132         AUDIT_ARG(value32, uap->data);
 133
 134         if (uap->req == PT_DENY_ATTACH) {
 135 #if (DEVELOPMENT || DEBUG) && CONFIG_EMBEDDED
 136                 if (PE_i_can_has_debugger(NULL))
 137                         return(0);
 138 #endif
 139                 proc_lock(p);
 140                 if (ISSET(p->p_lflag, P_LTRACED)) {
 141                         proc_unlock(p);
 142                         KERNEL_DEBUG_CONSTANT(BSDDBG_CODE(DBG_BSD_PROC, BSD_PROC_FRCEXIT) | DBG_FUNC_NONE,
 143                                               p->p_pid, W_EXITCODE(ENOTSUP, 0), 4, 0, 0);
 144                         exit1(p, W_EXITCODE(ENOTSUP, 0), retval);
 145
 146                         thread_exception_return();
 147                         /* NOTREACHED */
 148                 }
 149                 SET(p->p_lflag, P_LNOATTACH);
 150                 proc_unlock(p);
 151
 152                 return(0);
 153         }
 154
 155         if (uap->req == PT_FORCEQUOTA) {
 156                 if (kauth_cred_issuser(kauth_cred_get())) {
 157                         OSBitOrAtomic(P_FORCEQUOTA, &t->p_flag);
 158                         return (0);
 159                 } else
 160                         return (EPERM);
 161         }
 162
 163         /*
 164          *      Intercept and deal with "please trace me" request.
 165          */
 166         if (uap->req == PT_TRACE_ME) {
 167 retry_trace_me:;
 168                 proc_t pproc = proc_parent(p);
 169                 if (pproc == NULL)
 170                         return (EINVAL);
 171 #if CONFIG_MACF
 172                 /*
 173                  * NB: Cannot call kauth_authorize_process(..., KAUTH_PROCESS_CANTRACE, ...)
 174                  *     since that assumes the process being checked is the current process
 175                  *     when, in this case, it is the current process's parent.
 176                  *     Most of the other checks in cantrace() don't apply either.
 177                  */
 178                 if ((error = mac_proc_check_debug(pproc, p)) == 0) {
 179 #endif
 180                         proc_lock(p);
 181                         /* Make sure the process wasn't re-parented. */
 182                         if (p->p_ppid != pproc->p_pid) {
 183                                 proc_unlock(p);
 184                                 proc_rele(pproc);
 185                                 goto retry_trace_me;
 186                         }
 187                         SET(p->p_lflag, P_LTRACED);
 188                         /* Non-attached case, our tracer is our parent. */
 189                         p->p_oppid = p->p_ppid;
 190                         proc_unlock(p);
 191                         /* Child and parent will have to be able to run modified code. */
 192                         cs_allow_invalid(p);
 193                         cs_allow_invalid(pproc);
 194 #if CONFIG_MACF
 195                 }
 196 #endif
 197                 proc_rele(pproc);
 198                 return (error);
 199         }
 200         if (uap->req == PT_SIGEXC) {
 201                 proc_lock(p);
 202                 if (ISSET(p->p_lflag, P_LTRACED)) {
 203                         SET(p->p_lflag, P_LSIGEXC);
 204                         proc_unlock(p);
 205                         return(0);
 206                 } else {
 207                         proc_unlock(p);
 208                         return(EINVAL);
 209                 }
 210         }
 211
 212         /*
 213          * We do not want ptrace to do anything with kernel or launchd
 214          */
 215         if (uap->pid < 2) {
 216                 return(EPERM);
 217         }
 218
 219         /*
 220          *      Locate victim, and make sure it is traceable.
 221          */
 222         if ((t = proc_find(uap->pid)) == NULL)
 223                         return (ESRCH);
 224
 225         AUDIT_ARG(process, t);
 226
 227         task = t->task;
 228         if (uap->req == PT_ATTACHEXC) {
 229 #pragma clang diagnostic push
 230 #pragma clang diagnostic ignored "-Wdeprecated-declarations"
 231                 uap->req = PT_ATTACH;
 232                 tr_sigexc = 1;
 233         }
 234         if (uap->req == PT_ATTACH) {
 235 #pragma clang diagnostic pop
 236                 int             err;
 237
 238 #if CONFIG_EMBEDDED
 239                 if (tr_sigexc == 0) {
 240                         error = ENOTSUP;
 241                         goto out;
 242                 }
 243 #endif
 244
 245                 if ( kauth_authorize_process(proc_ucred(p), KAUTH_PROCESS_CANTRACE,
 246                                                                          t, (uintptr_t)&err, 0, 0) == 0 ) {
 247                         /* it's OK to attach */
 248                         proc_lock(t);
 249                         SET(t->p_lflag, P_LTRACED);
 250                         if (tr_sigexc)
 251                                 SET(t->p_lflag, P_LSIGEXC);
 252
 253                         t->p_oppid = t->p_ppid;
 254                         /* Check whether child and parent are allowed to run modified
 255                          * code (they'll have to) */
 256                         proc_unlock(t);
 257                         cs_allow_invalid(t);
 258                         cs_allow_invalid(p);
 259                         if (t->p_pptr != p)
 260                                 proc_reparentlocked(t, p, 1, 0);
 261
 262                         proc_lock(t);
 263                         if (get_task_userstop(task) > 0 ) {
 264                                 stopped = 1;
 265                         }
 266                         t->p_xstat = 0;
 267                         proc_unlock(t);
 268                         psignal(t, SIGSTOP);
 269                         /*
 270                          * If the process was stopped, wake up and run through
 271                          * issignal() again to properly connect to the tracing
 272                          * process.
 273                          */
 274                         if (stopped)
 275                                 task_resume(task);
 276                         error = 0;
 277                         goto out;
 278                 }
 279                 else {
 280                         /* not allowed to attach, proper error code returned by kauth_authorize_process */
 281                         if (ISSET(t->p_lflag, P_LNOATTACH)) {
 282                                 psignal(p, SIGSEGV);
 283                         }
 284
 285                         error = err;
 286                         goto out;
 287                 }
 288         }
 289
 290         /*
 291          * You can't do what you want to the process if:
 292          *      (1) It's not being traced at all,
 293          */
 294         proc_lock(t);
 295         if (!ISSET(t->p_lflag, P_LTRACED)) {
 296                 proc_unlock(t);
 297                 error = EPERM;
 298                 goto out;
 299         }
 300
 301         /*
 302          *      (2) it's not being traced by _you_, or
 303          */
 304         if (t->p_pptr != p) {
 305                 proc_unlock(t);
 306                 error = EBUSY;
 307                 goto out;
 308         }
 309
 310         /*
 311          *      (3) it's not currently stopped.
 312          */
 313         if (t->p_stat != SSTOP) {
 314                 proc_unlock(t);
 315                 error = EBUSY;
 316                 goto out;
 317         }
 318
 319         /*
 320          *      Mach version of ptrace executes request directly here,
 321          *      thus simplifying the interaction of ptrace and signals.
 322          */
 323         /* proc lock is held here */
 324         switch (uap->req) {
 325
 326         case PT_DETACH:
 327                 if (t->p_oppid != t->p_ppid) {
 328                         struct proc *pp;
 329
 330                         proc_unlock(t);
 331                         pp = proc_find(t->p_oppid);
 332                         if (pp != PROC_NULL) {
 333                                 proc_reparentlocked(t, pp, 1, 0);
 334                                 proc_rele(pp);
 335                         } else {
 336                                 /* original parent exited while traced */
 337                                 proc_list_lock();
 338                                 t->p_listflag |= P_LIST_DEADPARENT;
 339                                 proc_list_unlock();
 340                                 proc_reparentlocked(t, initproc, 1, 0);
 341                         }
 342                         proc_lock(t);
 343                 }
 344
 345                 t->p_oppid = 0;
 346                 CLR(t->p_lflag, P_LTRACED);
 347                 CLR(t->p_lflag, P_LSIGEXC);
 348                 proc_unlock(t);
 349                 goto resume;
 350
 351         case PT_KILL:
 352                 /*
 353                  *      Tell child process to kill itself after it
 354                  *      is resumed by adding NSIG to p_cursig. [see issig]
 355                  */
 356                 proc_unlock(t);
 357 #if CONFIG_MACF
 358                 error = mac_proc_check_signal(p, t, SIGKILL);
 359                 if (0 != error)
 360                         goto resume;
 361 #endif
 362                 psignal(t, SIGKILL);
 363                 goto resume;
 364
 365         case PT_STEP:                   /* single step the child */
 366         case PT_CONTINUE:               /* continue the child */
 367                 proc_unlock(t);
 368                 th_act = (thread_t)get_firstthread(task);
 369                 if (th_act == THREAD_NULL) {
 370                         error = EINVAL;
 371                         goto out;
 372                 }
 373
 374                 /* force use of Mach SPIs (and task_for_pid security checks) to adjust PC */
 375                 if (uap->addr != (user_addr_t)1) {
 376                         error = ENOTSUP;
 377                         goto out;
 378                 }
 379
 380                 if ((unsigned)uap->data >= NSIG) {
 381                         error = EINVAL;
 382                         goto out;
 383                 }
 384
 385                 if (uap->data != 0) {
 386 #if CONFIG_MACF
 387                         error = mac_proc_check_signal(p, t, uap->data);
 388                         if (0 != error)
 389                                 goto out;
 390 #endif
 391                         psignal(t, uap->data);
 392                 }
 393
 394                 if (uap->req == PT_STEP) {
 395                         /*
 396                          * set trace bit
 397                          * we use sending SIGSTOP as a comparable security check.
 398                          */
 399 #if CONFIG_MACF
 400                         error = mac_proc_check_signal(p, t, SIGSTOP);
 401                         if (0 != error) {
 402                                 goto out;
 403                         }
 404 #endif
 405                         if (thread_setsinglestep(th_act, 1) != KERN_SUCCESS) {
 406                                 error = ENOTSUP;
 407                                 goto out;
 408                         }
 409                 } else {
 410                         /*
 411                          * clear trace bit if on
 412                          * we use sending SIGCONT as a comparable security check.
 413                          */
 414 #if CONFIG_MACF
 415                         error = mac_proc_check_signal(p, t, SIGCONT);
 416                         if (0 != error) {
 417                                 goto out;
 418                         }
 419 #endif
 420                         if (thread_setsinglestep(th_act, 0) != KERN_SUCCESS) {
 421                                 error = ENOTSUP;
 422                                 goto out;
 423                         }
 424                 }
 425         resume:
 426                 proc_lock(t);
 427                 t->p_xstat = uap->data;
 428                 t->p_stat = SRUN;
 429                 if (t->sigwait) {
 430                         wakeup((caddr_t)&(t->sigwait));
 431                         proc_unlock(t);
 432                         if ((t->p_lflag & P_LSIGEXC) == 0) {
 433                                 task_resume(task);
 434                         }
 435                 } else
 436                         proc_unlock(t);
 437
 438                 break;
 439
 440         case PT_THUPDATE:  {
 441                 proc_unlock(t);
 442                 if ((unsigned)uap->data >= NSIG) {
 443                         error = EINVAL;
 444                         goto out;
 445                 }
 446                 th_act = port_name_to_thread(CAST_MACH_PORT_TO_NAME(uap->addr));
 447                 if (th_act == THREAD_NULL) {
 448                         error = ESRCH;
 449                         goto out;
 450                 }
 451                 ut = (uthread_t)get_bsdthread_info(th_act);
 452                 if (uap->data)
 453                         ut->uu_siglist |= sigmask(uap->data);
 454                 proc_lock(t);
 455                 t->p_xstat = uap->data;
 456                 t->p_stat = SRUN;
 457                 proc_unlock(t);
 458                 thread_deallocate(th_act);
 459                 error = 0;
 460                 }
 461                 break;
 462         default:
 463                 proc_unlock(t);
 464                 error = EINVAL;
 465                 goto out;
 466         }
 467
 468         error = 0;
 469 out:
 470         proc_rele(t);
 471         return(error);
 472 }
 473
 474
 475 /*
 476  * determine if one process (cur_procp) can trace another process (traced_procp).
 477  */
 478
 479 int
 480 cantrace(proc_t cur_procp, kauth_cred_t creds, proc_t traced_procp, int *errp)
 481 {
 482         int             my_err;
 483         /*
 484          * You can't trace a process if:
 485          *      (1) it's the process that's doing the tracing,
 486          */
 487         if (traced_procp->p_pid == cur_procp->p_pid) {
 488                 *errp = EINVAL;
 489                 return (0);
 490         }
 491
 492         /*
 493          *      (2) it's already being traced, or
 494          */
 495         if (ISSET(traced_procp->p_lflag, P_LTRACED)) {
 496                 *errp = EBUSY;
 497                 return (0);
 498         }
 499
 500         /*
 501          *      (3) it's not owned by you, or is set-id on exec
 502          *          (unless you're root).
 503          */
 504         if ((kauth_cred_getruid(creds) != kauth_cred_getruid(proc_ucred(traced_procp)) ||
 505                 ISSET(traced_procp->p_flag, P_SUGID)) &&
 506                 (my_err = suser(creds, &cur_procp->p_acflag)) != 0) {
 507                 *errp = my_err;
 508                 return (0);
 509         }
 510
 511         if ((cur_procp->p_lflag & P_LTRACED) && isinferior(cur_procp, traced_procp)) {
 512                 *errp = EPERM;
 513                 return (0);
 514         }
 515
 516         if (ISSET(traced_procp->p_lflag, P_LNOATTACH)) {
 517                 *errp = EBUSY;
 518                 return (0);
 519         }
 520
 521 #if CONFIG_MACF
 522         if ((my_err = mac_proc_check_debug(cur_procp, traced_procp)) != 0) {
 523                 *errp = my_err;
 524                 return (0);
 525         }
 526 #endif
 527
 528         return(1);
 529 }