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
  87 #include <security/audit/audit.h>
  88
  89 #include <kern/task.h>
  90 #include <kern/thread.h>
  91
  92 #include <mach/task.h>                  /* for task_resume() */
  93 #include <kern/sched_prim.h>            /* for thread_exception_return() */
  94
  95 #include <vm/vm_protos.h>               /* cs_allow_invalid() */
  96
  97 /* XXX ken/bsd_kern.c - prototype should be in common header */
  98 int get_task_userstop(task_t);
  99
 100 /* Macros to clear/set/test flags. */
 101 #define SET(t, f)       (t) |= (f)
 102 #define CLR(t, f)       (t) &= ~(f)
 103 #define ISSET(t, f)     ((t) & (f))
 104
 105 extern thread_t port_name_to_thread(mach_port_name_t port_name);
 106 extern thread_t get_firstthread(task_t);
 107
 108
 109 /*
 110  * sys-trace system call.
 111  */
 112
 113 int
 114 ptrace(struct proc *p, struct ptrace_args *uap, int32_t *retval)
 115 {
 116         struct proc *t = current_proc();        /* target process */
 117         task_t          task;
 118         thread_t        th_act;
 119         struct uthread  *ut;
 120         int tr_sigexc = 0;
 121         int error = 0;
 122         int stopped = 0;
 123
 124         AUDIT_ARG(cmd, uap->req);
 125         AUDIT_ARG(pid, uap->pid);
 126         AUDIT_ARG(addr, uap->addr);
 127         AUDIT_ARG(value32, uap->data);
 128
 129         if (uap->req == PT_DENY_ATTACH) {
 130                 proc_lock(p);
 131                 if (ISSET(p->p_lflag, P_LTRACED)) {
 132                         proc_unlock(p);
 133                         KERNEL_DEBUG_CONSTANT(BSDDBG_CODE(DBG_BSD_PROC, BSD_PROC_FRCEXIT) | DBG_FUNC_NONE,
 134                                               p->p_pid, W_EXITCODE(ENOTSUP, 0), 4, 0, 0);
 135                         exit1(p, W_EXITCODE(ENOTSUP, 0), retval);
 136                         /* drop funnel before we return */
 137                         thread_exception_return();
 138                         /* NOTREACHED */
 139                 }
 140                 SET(p->p_lflag, P_LNOATTACH);
 141                 proc_unlock(p);
 142
 143                 return(0);
 144         }
 145
 146         if (uap->req == PT_FORCEQUOTA) {
 147                 if (is_suser()) {
 148                         OSBitOrAtomic(P_FORCEQUOTA, &t->p_flag);
 149                         return (0);
 150                 } else
 151                         return (EPERM);
 152         }
 153
 154         /*
 155          *      Intercept and deal with "please trace me" request.
 156          */
 157         if (uap->req == PT_TRACE_ME) {
 158                 proc_lock(p);
 159                 SET(p->p_lflag, P_LTRACED);
 160                 /* Non-attached case, our tracer is our parent. */
 161                 p->p_oppid = p->p_ppid;
 162                 /* Check whether child and parent are allowed to run modified
 163                  * code (they'll have to) */
 164                 struct proc *pproc=proc_find(p->p_oppid);
 165                 proc_unlock(p);
 166                 cs_allow_invalid(p);
 167                 cs_allow_invalid(pproc);
 168                 proc_rele(pproc);
 169                 return(0);
 170         }
 171         if (uap->req == PT_SIGEXC) {
 172                 proc_lock(p);
 173                 if (ISSET(p->p_lflag, P_LTRACED)) {
 174                         SET(p->p_lflag, P_LSIGEXC);
 175                         proc_unlock(p);
 176                         return(0);
 177                 } else {
 178                         proc_unlock(p);
 179                         return(EINVAL);
 180                 }
 181         }
 182
 183         /*
 184          * We do not want ptrace to do anything with kernel or launchd
 185          */
 186         if (uap->pid < 2) {
 187                 return(EPERM);
 188         }
 189
 190         /*
 191          *      Locate victim, and make sure it is traceable.
 192          */
 193         if ((t = proc_find(uap->pid)) == NULL)
 194                         return (ESRCH);
 195
 196         AUDIT_ARG(process, t);
 197
 198         task = t->task;
 199         if (uap->req == PT_ATTACHEXC) {
 200                 uap->req = PT_ATTACH;
 201                 tr_sigexc = 1;
 202         }
 203         if (uap->req == PT_ATTACH) {
 204                 int             err;
 205
 206                 if ( kauth_authorize_process(proc_ucred(p), KAUTH_PROCESS_CANTRACE,
 207                                                                          t, (uintptr_t)&err, 0, 0) == 0 ) {
 208                         /* it's OK to attach */
 209                         proc_lock(t);
 210                         SET(t->p_lflag, P_LTRACED);
 211                         if (tr_sigexc)
 212                                 SET(t->p_lflag, P_LSIGEXC);
 213
 214                         t->p_oppid = t->p_ppid;
 215                         /* Check whether child and parent are allowed to run modified
 216                          * code (they'll have to) */
 217                         proc_unlock(t);
 218                         cs_allow_invalid(t);
 219                         cs_allow_invalid(p);
 220                         if (t->p_pptr != p)
 221                                 proc_reparentlocked(t, p, 1, 0);
 222
 223                         proc_lock(t);
 224                         if (get_task_userstop(task) > 0 ) {
 225                                 stopped = 1;
 226                         }
 227                         t->p_xstat = 0;
 228                         proc_unlock(t);
 229                         psignal(t, SIGSTOP);
 230                         /*
 231                          * If the process was stopped, wake up and run through
 232                          * issignal() again to properly connect to the tracing
 233                          * process.
 234                          */
 235                         if (stopped)
 236                                 task_resume(task);
 237                         error = 0;
 238                         goto out;
 239                 }
 240                 else {
 241                         /* not allowed to attach, proper error code returned by kauth_authorize_process */
 242                         if (ISSET(t->p_lflag, P_LNOATTACH)) {
 243                                 psignal(p, SIGSEGV);
 244                         }
 245
 246                         error = err;
 247                         goto out;
 248                 }
 249         }
 250
 251         /*
 252          * You can't do what you want to the process if:
 253          *      (1) It's not being traced at all,
 254          */
 255         proc_lock(t);
 256         if (!ISSET(t->p_lflag, P_LTRACED)) {
 257                 proc_unlock(t);
 258                 error = EPERM;
 259                 goto out;
 260         }
 261
 262         /*
 263          *      (2) it's not being traced by _you_, or
 264          */
 265         if (t->p_pptr != p) {
 266                 proc_unlock(t);
 267                 error = EBUSY;
 268                 goto out;
 269         }
 270
 271         /*
 272          *      (3) it's not currently stopped.
 273          */
 274         if (t->p_stat != SSTOP) {
 275                 proc_unlock(t);
 276                 error = EBUSY;
 277                 goto out;
 278         }
 279
 280         /*
 281          *      Mach version of ptrace executes request directly here,
 282          *      thus simplifying the interaction of ptrace and signals.
 283          */
 284         /* proc lock is held here */
 285         switch (uap->req) {
 286
 287         case PT_DETACH:
 288                 if (t->p_oppid != t->p_ppid) {
 289                         struct proc *pp;
 290
 291                         proc_unlock(t);
 292                         pp = proc_find(t->p_oppid);
 293                         proc_reparentlocked(t, pp ? pp : initproc, 1, 0);
 294                         if (pp != PROC_NULL)
 295                                 proc_rele(pp);
 296                         proc_lock(t);
 297
 298                 }
 299
 300                 t->p_oppid = 0;
 301                 CLR(t->p_lflag, P_LTRACED);
 302                 CLR(t->p_lflag, P_LSIGEXC);
 303                 proc_unlock(t);
 304                 goto resume;
 305
 306         case PT_KILL:
 307                 /*
 308                  *      Tell child process to kill itself after it
 309                  *      is resumed by adding NSIG to p_cursig. [see issig]
 310                  */
 311                 proc_unlock(t);
 312                 psignal(t, SIGKILL);
 313                 goto resume;
 314
 315         case PT_STEP:                   /* single step the child */
 316         case PT_CONTINUE:               /* continue the child */
 317                 proc_unlock(t);
 318                 th_act = (thread_t)get_firstthread(task);
 319                 if (th_act == THREAD_NULL) {
 320                         error = EINVAL;
 321                         goto out;
 322                 }
 323
 324                 if (uap->addr != (user_addr_t)1) {
 325 #if defined(ppc)
 326 #define ALIGNED(addr,size)      (((unsigned)(addr)&((size)-1))==0)
 327                         if (!ALIGNED((int)uap->addr, sizeof(int)))
 328                                 return (ERESTART);
 329 #undef  ALIGNED
 330 #endif
 331                         thread_setentrypoint(th_act, uap->addr);
 332                 }
 333
 334                 if ((unsigned)uap->data >= NSIG) {
 335                         error = EINVAL;
 336                         goto out;
 337                 }
 338
 339                 if (uap->data != 0) {
 340                         psignal(t, uap->data);
 341                 }
 342
 343                 if (uap->req == PT_STEP) {
 344                         /*
 345                          * set trace bit
 346                          */
 347                         if (thread_setsinglestep(th_act, 1) != KERN_SUCCESS) {
 348                                 error = ENOTSUP;
 349                                 goto out;
 350                         }
 351                 } else {
 352                         /*
 353                          * clear trace bit if on
 354                          */
 355                         if (thread_setsinglestep(th_act, 0) != KERN_SUCCESS) {
 356                                 error = ENOTSUP;
 357                                 goto out;
 358                         }
 359                 }
 360         resume:
 361                 proc_lock(t);
 362                 t->p_xstat = uap->data;
 363                 t->p_stat = SRUN;
 364                 if (t->sigwait) {
 365                         wakeup((caddr_t)&(t->sigwait));
 366                         proc_unlock(t);
 367                         if ((t->p_lflag & P_LSIGEXC) == 0) {
 368                                 task_resume(task);
 369                         }
 370                 } else
 371                         proc_unlock(t);
 372
 373                 break;
 374
 375         case PT_THUPDATE:  {
 376                 proc_unlock(t);
 377                 if ((unsigned)uap->data >= NSIG) {
 378                         error = EINVAL;
 379                         goto out;
 380                 }
 381                 th_act = port_name_to_thread(CAST_MACH_PORT_TO_NAME(uap->addr));
 382                 if (th_act == THREAD_NULL)
 383                         return (ESRCH);
 384                 ut = (uthread_t)get_bsdthread_info(th_act);
 385                 if (uap->data)
 386                         ut->uu_siglist |= sigmask(uap->data);
 387                 proc_lock(t);
 388                 t->p_xstat = uap->data;
 389                 t->p_stat = SRUN;
 390                 proc_unlock(t);
 391                 thread_deallocate(th_act);
 392                 error = 0;
 393                 }
 394                 break;
 395         default:
 396                 proc_unlock(t);
 397                 error = EINVAL;
 398                 goto out;
 399         }
 400
 401         error = 0;
 402 out:
 403         proc_rele(t);
 404         return(error);
 405 }
 406
 407
 408 /*
 409  * determine if one process (cur_procp) can trace another process (traced_procp).
 410  */
 411
 412 int
 413 cantrace(proc_t cur_procp, kauth_cred_t creds, proc_t traced_procp, int *errp)
 414 {
 415         int             my_err;
 416         /*
 417          * You can't trace a process if:
 418          *      (1) it's the process that's doing the tracing,
 419          */
 420         if (traced_procp->p_pid == cur_procp->p_pid) {
 421                 *errp = EINVAL;
 422                 return (0);
 423         }
 424
 425         /*
 426          *      (2) it's already being traced, or
 427          */
 428         if (ISSET(traced_procp->p_lflag, P_LTRACED)) {
 429                 *errp = EBUSY;
 430                 return (0);
 431         }
 432
 433         /*
 434          *      (3) it's not owned by you, or is set-id on exec
 435          *          (unless you're root).
 436          */
 437         if ((creds->cr_ruid != proc_ucred(traced_procp)->cr_ruid ||
 438                 ISSET(traced_procp->p_flag, P_SUGID)) &&
 439                 (my_err = suser(creds, &cur_procp->p_acflag)) != 0) {
 440                 *errp = my_err;
 441                 return (0);
 442         }
 443
 444         if ((cur_procp->p_lflag & P_LTRACED) && isinferior(cur_procp, traced_procp)) {
 445                 *errp = EPERM;
 446                 return (0);
 447         }
 448
 449         if (ISSET(traced_procp->p_lflag, P_LNOATTACH)) {
 450                 *errp = EBUSY;
 451                 return (0);
 452         }
 453         return(1);
 454 }