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                         /* drop funnel before we return */
 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                 proc_lock(p);
 160                 SET(p->p_lflag, P_LTRACED);
 161                 /* Non-attached case, our tracer is our parent. */
 162                 p->p_oppid = p->p_ppid;
 163                 /* Check whether child and parent are allowed to run modified
 164                  * code (they'll have to) */
 165                 struct proc *pproc=proc_find(p->p_oppid);
 166                 proc_unlock(p);
 167                 cs_allow_invalid(p);
 168                 if(pproc) {
 169                         cs_allow_invalid(pproc);
 170                         proc_rele(pproc);
 171                 }
 172                 return(0);
 173         }
 174         if (uap->req == PT_SIGEXC) {
 175                 proc_lock(p);
 176                 if (ISSET(p->p_lflag, P_LTRACED)) {
 177                         SET(p->p_lflag, P_LSIGEXC);
 178                         proc_unlock(p);
 179                         return(0);
 180                 } else {
 181                         proc_unlock(p);
 182                         return(EINVAL);
 183                 }
 184         }
 185
 186         /*
 187          * We do not want ptrace to do anything with kernel or launchd
 188          */
 189         if (uap->pid < 2) {
 190                 return(EPERM);
 191         }
 192
 193         /*
 194          *      Locate victim, and make sure it is traceable.
 195          */
 196         if ((t = proc_find(uap->pid)) == NULL)
 197                         return (ESRCH);
 198
 199         AUDIT_ARG(process, t);
 200
 201         task = t->task;
 202         if (uap->req == PT_ATTACHEXC) {
 203                 uap->req = PT_ATTACH;
 204                 tr_sigexc = 1;
 205         }
 206         if (uap->req == PT_ATTACH) {
 207                 int             err;
 208
 209                 if ( kauth_authorize_process(proc_ucred(p), KAUTH_PROCESS_CANTRACE,
 210                                                                          t, (uintptr_t)&err, 0, 0) == 0 ) {
 211                         /* it's OK to attach */
 212                         proc_lock(t);
 213                         SET(t->p_lflag, P_LTRACED);
 214                         if (tr_sigexc)
 215                                 SET(t->p_lflag, P_LSIGEXC);
 216
 217                         t->p_oppid = t->p_ppid;
 218                         /* Check whether child and parent are allowed to run modified
 219                          * code (they'll have to) */
 220                         proc_unlock(t);
 221                         cs_allow_invalid(t);
 222                         cs_allow_invalid(p);
 223                         if (t->p_pptr != p)
 224                                 proc_reparentlocked(t, p, 1, 0);
 225
 226                         proc_lock(t);
 227                         if (get_task_userstop(task) > 0 ) {
 228                                 stopped = 1;
 229                         }
 230                         t->p_xstat = 0;
 231                         proc_unlock(t);
 232                         psignal(t, SIGSTOP);
 233                         /*
 234                          * If the process was stopped, wake up and run through
 235                          * issignal() again to properly connect to the tracing
 236                          * process.
 237                          */
 238                         if (stopped)
 239                                 task_resume(task);
 240                         error = 0;
 241                         goto out;
 242                 }
 243                 else {
 244                         /* not allowed to attach, proper error code returned by kauth_authorize_process */
 245                         if (ISSET(t->p_lflag, P_LNOATTACH)) {
 246                                 psignal(p, SIGSEGV);
 247                         }
 248
 249                         error = err;
 250                         goto out;
 251                 }
 252         }
 253
 254         /*
 255          * You can't do what you want to the process if:
 256          *      (1) It's not being traced at all,
 257          */
 258         proc_lock(t);
 259         if (!ISSET(t->p_lflag, P_LTRACED)) {
 260                 proc_unlock(t);
 261                 error = EPERM;
 262                 goto out;
 263         }
 264
 265         /*
 266          *      (2) it's not being traced by _you_, or
 267          */
 268         if (t->p_pptr != p) {
 269                 proc_unlock(t);
 270                 error = EBUSY;
 271                 goto out;
 272         }
 273
 274         /*
 275          *      (3) it's not currently stopped.
 276          */
 277         if (t->p_stat != SSTOP) {
 278                 proc_unlock(t);
 279                 error = EBUSY;
 280                 goto out;
 281         }
 282
 283         /*
 284          *      Mach version of ptrace executes request directly here,
 285          *      thus simplifying the interaction of ptrace and signals.
 286          */
 287         /* proc lock is held here */
 288         switch (uap->req) {
 289
 290         case PT_DETACH:
 291                 if (t->p_oppid != t->p_ppid) {
 292                         struct proc *pp;
 293
 294                         proc_unlock(t);
 295                         pp = proc_find(t->p_oppid);
 296                         if (pp != PROC_NULL) {
 297                                 proc_reparentlocked(t, pp, 1, 0);
 298                                 proc_rele(pp);
 299                         } else {
 300                                 /* original parent exited while traced */
 301                                 proc_list_lock();
 302                                 t->p_listflag |= P_LIST_DEADPARENT;
 303                                 proc_list_unlock();
 304                                 proc_reparentlocked(t, initproc, 1, 0);
 305                         }
 306                         proc_lock(t);
 307                 }
 308
 309                 t->p_oppid = 0;
 310                 CLR(t->p_lflag, P_LTRACED);
 311                 CLR(t->p_lflag, P_LSIGEXC);
 312                 proc_unlock(t);
 313                 goto resume;
 314
 315         case PT_KILL:
 316                 /*
 317                  *      Tell child process to kill itself after it
 318                  *      is resumed by adding NSIG to p_cursig. [see issig]
 319                  */
 320                 proc_unlock(t);
 321 #if CONFIG_MACF
 322                 error = mac_proc_check_signal(p, t, SIGKILL);
 323                 if (0 != error)
 324                         goto resume;
 325 #endif
 326                 psignal(t, SIGKILL);
 327                 goto resume;
 328
 329         case PT_STEP:                   /* single step the child */
 330         case PT_CONTINUE:               /* continue the child */
 331                 proc_unlock(t);
 332                 th_act = (thread_t)get_firstthread(task);
 333                 if (th_act == THREAD_NULL) {
 334                         error = EINVAL;
 335                         goto out;
 336                 }
 337
 338                 /* force use of Mach SPIs (and task_for_pid security checks) to adjust PC */
 339                 if (uap->addr != (user_addr_t)1) {
 340                         error = ENOTSUP;
 341                         goto out;
 342                 }
 343
 344                 if ((unsigned)uap->data >= NSIG) {
 345                         error = EINVAL;
 346                         goto out;
 347                 }
 348
 349                 if (uap->data != 0) {
 350                         psignal(t, uap->data);
 351                 }
 352
 353                 if (uap->req == PT_STEP) {
 354                         /*
 355                          * set trace bit
 356                          * we use sending SIGSTOP as a comparable security check.
 357                          */
 358 #if CONFIG_MACF
 359                         error = mac_proc_check_signal(p, t, SIGSTOP);
 360                         if (0 != error) {
 361                                 goto out;
 362                         }
 363 #endif
 364                         if (thread_setsinglestep(th_act, 1) != KERN_SUCCESS) {
 365                                 error = ENOTSUP;
 366                                 goto out;
 367                         }
 368                 } else {
 369                         /*
 370                          * clear trace bit if on
 371                          * we use sending SIGCONT as a comparable security check.
 372                          */
 373 #if CONFIG_MACF
 374                         error = mac_proc_check_signal(p, t, SIGCONT);
 375                         if (0 != error) {
 376                                 goto out;
 377                         }
 378 #endif
 379                         if (thread_setsinglestep(th_act, 0) != KERN_SUCCESS) {
 380                                 error = ENOTSUP;
 381                                 goto out;
 382                         }
 383                 }
 384         resume:
 385                 proc_lock(t);
 386                 t->p_xstat = uap->data;
 387                 t->p_stat = SRUN;
 388                 if (t->sigwait) {
 389                         wakeup((caddr_t)&(t->sigwait));
 390                         proc_unlock(t);
 391                         if ((t->p_lflag & P_LSIGEXC) == 0) {
 392                                 task_resume(task);
 393                         }
 394                 } else
 395                         proc_unlock(t);
 396
 397                 break;
 398
 399         case PT_THUPDATE:  {
 400                 proc_unlock(t);
 401                 if ((unsigned)uap->data >= NSIG) {
 402                         error = EINVAL;
 403                         goto out;
 404                 }
 405                 th_act = port_name_to_thread(CAST_MACH_PORT_TO_NAME(uap->addr));
 406                 if (th_act == THREAD_NULL)
 407                         return (ESRCH);
 408                 ut = (uthread_t)get_bsdthread_info(th_act);
 409                 if (uap->data)
 410                         ut->uu_siglist |= sigmask(uap->data);
 411                 proc_lock(t);
 412                 t->p_xstat = uap->data;
 413                 t->p_stat = SRUN;
 414                 proc_unlock(t);
 415                 thread_deallocate(th_act);
 416                 error = 0;
 417                 }
 418                 break;
 419         default:
 420                 proc_unlock(t);
 421                 error = EINVAL;
 422                 goto out;
 423         }
 424
 425         error = 0;
 426 out:
 427         proc_rele(t);
 428         return(error);
 429 }
 430
 431
 432 /*
 433  * determine if one process (cur_procp) can trace another process (traced_procp).
 434  */
 435
 436 int
 437 cantrace(proc_t cur_procp, kauth_cred_t creds, proc_t traced_procp, int *errp)
 438 {
 439         int             my_err;
 440         /*
 441          * You can't trace a process if:
 442          *      (1) it's the process that's doing the tracing,
 443          */
 444         if (traced_procp->p_pid == cur_procp->p_pid) {
 445                 *errp = EINVAL;
 446                 return (0);
 447         }
 448
 449         /*
 450          *      (2) it's already being traced, or
 451          */
 452         if (ISSET(traced_procp->p_lflag, P_LTRACED)) {
 453                 *errp = EBUSY;
 454                 return (0);
 455         }
 456
 457         /*
 458          *      (3) it's not owned by you, or is set-id on exec
 459          *          (unless you're root).
 460          */
 461         if ((kauth_cred_getruid(creds) != kauth_cred_getruid(proc_ucred(traced_procp)) ||
 462                 ISSET(traced_procp->p_flag, P_SUGID)) &&
 463                 (my_err = suser(creds, &cur_procp->p_acflag)) != 0) {
 464                 *errp = my_err;
 465                 return (0);
 466         }
 467
 468         if ((cur_procp->p_lflag & P_LTRACED) && isinferior(cur_procp, traced_procp)) {
 469                 *errp = EPERM;
 470                 return (0);
 471         }
 472
 473         if (ISSET(traced_procp->p_lflag, P_LNOATTACH)) {
 474                 *errp = EBUSY;
 475                 return (0);
 476         }
 477         return(1);
 478 }