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 #include <pexpert/pexpert.h>
  98
  99 /* XXX ken/bsd_kern.c - prototype should be in common header */
 100 int get_task_userstop(task_t);
 101
 102 /* Macros to clear/set/test flags. */
 103 #define SET(t, f)       (t) |= (f)
 104 #define CLR(t, f)       (t) &= ~(f)
 105 #define ISSET(t, f)     ((t) & (f))
 106
 107 extern thread_t port_name_to_thread(mach_port_name_t port_name);
 108 extern thread_t get_firstthread(task_t);
 109
 110
 111 /*
 112  * sys-trace system call.
 113  */
 114
 115 int
 116 ptrace(struct proc *p, struct ptrace_args *uap, int32_t *retval)
 117 {
 118         struct proc *t = current_proc();        /* target process */
 119         task_t          task;
 120         thread_t        th_act;
 121         struct uthread  *ut;
 122         int tr_sigexc = 0;
 123         int error = 0;
 124         int stopped = 0;
 125
 126         AUDIT_ARG(cmd, uap->req);
 127         AUDIT_ARG(pid, uap->pid);
 128         AUDIT_ARG(addr, uap->addr);
 129         AUDIT_ARG(value32, uap->data);
 130
 131         if (uap->req == PT_DENY_ATTACH) {
 132 #if (DEVELOPMENT || DEBUG) && defined(__arm__)
 133                 if (PE_i_can_has_debugger(NULL))
 134                         return(0);
 135 #endif
 136                 proc_lock(p);
 137                 if (ISSET(p->p_lflag, P_LTRACED)) {
 138                         proc_unlock(p);
 139                         KERNEL_DEBUG_CONSTANT(BSDDBG_CODE(DBG_BSD_PROC, BSD_PROC_FRCEXIT) | DBG_FUNC_NONE,
 140                                               p->p_pid, W_EXITCODE(ENOTSUP, 0), 4, 0, 0);
 141                         exit1(p, W_EXITCODE(ENOTSUP, 0), retval);
 142                         /* drop funnel before we return */
 143                         thread_exception_return();
 144                         /* NOTREACHED */
 145                 }
 146                 SET(p->p_lflag, P_LNOATTACH);
 147                 proc_unlock(p);
 148
 149                 return(0);
 150         }
 151
 152         if (uap->req == PT_FORCEQUOTA) {
 153                 if (is_suser()) {
 154                         OSBitOrAtomic(P_FORCEQUOTA, &t->p_flag);
 155                         return (0);
 156                 } else
 157                         return (EPERM);
 158         }
 159
 160         /*
 161          *      Intercept and deal with "please trace me" request.
 162          */
 163         if (uap->req == PT_TRACE_ME) {
 164                 proc_lock(p);
 165                 SET(p->p_lflag, P_LTRACED);
 166                 /* Non-attached case, our tracer is our parent. */
 167                 p->p_oppid = p->p_ppid;
 168                 /* Check whether child and parent are allowed to run modified
 169                  * code (they'll have to) */
 170                 struct proc *pproc=proc_find(p->p_oppid);
 171                 proc_unlock(p);
 172                 cs_allow_invalid(p);
 173                 if(pproc) {
 174                         cs_allow_invalid(pproc);
 175                         proc_rele(pproc);
 176                 }
 177                 return(0);
 178         }
 179         if (uap->req == PT_SIGEXC) {
 180                 proc_lock(p);
 181                 if (ISSET(p->p_lflag, P_LTRACED)) {
 182                         SET(p->p_lflag, P_LSIGEXC);
 183                         proc_unlock(p);
 184                         return(0);
 185                 } else {
 186                         proc_unlock(p);
 187                         return(EINVAL);
 188                 }
 189         }
 190
 191         /*
 192          * We do not want ptrace to do anything with kernel or launchd
 193          */
 194         if (uap->pid < 2) {
 195                 return(EPERM);
 196         }
 197
 198         /*
 199          *      Locate victim, and make sure it is traceable.
 200          */
 201         if ((t = proc_find(uap->pid)) == NULL)
 202                         return (ESRCH);
 203
 204         AUDIT_ARG(process, t);
 205
 206         task = t->task;
 207         if (uap->req == PT_ATTACHEXC) {
 208                 uap->req = PT_ATTACH;
 209                 tr_sigexc = 1;
 210         }
 211         if (uap->req == PT_ATTACH) {
 212                 int             err;
 213
 214                 if ( kauth_authorize_process(proc_ucred(p), KAUTH_PROCESS_CANTRACE,
 215                                                                          t, (uintptr_t)&err, 0, 0) == 0 ) {
 216                         /* it's OK to attach */
 217                         proc_lock(t);
 218                         SET(t->p_lflag, P_LTRACED);
 219                         if (tr_sigexc)
 220                                 SET(t->p_lflag, P_LSIGEXC);
 221
 222                         t->p_oppid = t->p_ppid;
 223                         /* Check whether child and parent are allowed to run modified
 224                          * code (they'll have to) */
 225                         proc_unlock(t);
 226                         cs_allow_invalid(t);
 227                         cs_allow_invalid(p);
 228                         if (t->p_pptr != p)
 229                                 proc_reparentlocked(t, p, 1, 0);
 230
 231                         proc_lock(t);
 232                         if (get_task_userstop(task) > 0 ) {
 233                                 stopped = 1;
 234                         }
 235                         t->p_xstat = 0;
 236                         proc_unlock(t);
 237                         psignal(t, SIGSTOP);
 238                         /*
 239                          * If the process was stopped, wake up and run through
 240                          * issignal() again to properly connect to the tracing
 241                          * process.
 242                          */
 243                         if (stopped)
 244                                 task_resume(task);
 245                         error = 0;
 246                         goto out;
 247                 }
 248                 else {
 249                         /* not allowed to attach, proper error code returned by kauth_authorize_process */
 250                         if (ISSET(t->p_lflag, P_LNOATTACH)) {
 251                                 psignal(p, SIGSEGV);
 252                         }
 253
 254                         error = err;
 255                         goto out;
 256                 }
 257         }
 258
 259         /*
 260          * You can't do what you want to the process if:
 261          *      (1) It's not being traced at all,
 262          */
 263         proc_lock(t);
 264         if (!ISSET(t->p_lflag, P_LTRACED)) {
 265                 proc_unlock(t);
 266                 error = EPERM;
 267                 goto out;
 268         }
 269
 270         /*
 271          *      (2) it's not being traced by _you_, or
 272          */
 273         if (t->p_pptr != p) {
 274                 proc_unlock(t);
 275                 error = EBUSY;
 276                 goto out;
 277         }
 278
 279         /*
 280          *      (3) it's not currently stopped.
 281          */
 282         if (t->p_stat != SSTOP) {
 283                 proc_unlock(t);
 284                 error = EBUSY;
 285                 goto out;
 286         }
 287
 288         /*
 289          *      Mach version of ptrace executes request directly here,
 290          *      thus simplifying the interaction of ptrace and signals.
 291          */
 292         /* proc lock is held here */
 293         switch (uap->req) {
 294
 295         case PT_DETACH:
 296                 if (t->p_oppid != t->p_ppid) {
 297                         struct proc *pp;
 298
 299                         proc_unlock(t);
 300                         pp = proc_find(t->p_oppid);
 301                         proc_reparentlocked(t, pp ? pp : initproc, 1, 0);
 302                         if (pp != PROC_NULL)
 303                                 proc_rele(pp);
 304                         proc_lock(t);
 305
 306                 }
 307
 308                 t->p_oppid = 0;
 309                 CLR(t->p_lflag, P_LTRACED);
 310                 CLR(t->p_lflag, P_LSIGEXC);
 311                 proc_unlock(t);
 312                 goto resume;
 313
 314         case PT_KILL:
 315                 /*
 316                  *      Tell child process to kill itself after it
 317                  *      is resumed by adding NSIG to p_cursig. [see issig]
 318                  */
 319                 proc_unlock(t);
 320                 psignal(t, SIGKILL);
 321                 goto resume;
 322
 323         case PT_STEP:                   /* single step the child */
 324         case PT_CONTINUE:               /* continue the child */
 325                 proc_unlock(t);
 326                 th_act = (thread_t)get_firstthread(task);
 327                 if (th_act == THREAD_NULL) {
 328                         error = EINVAL;
 329                         goto out;
 330                 }
 331
 332                 if (uap->addr != (user_addr_t)1) {
 333 #if defined(ppc)
 334 #define ALIGNED(addr,size)      (((unsigned)(addr)&((size)-1))==0)
 335                         if (!ALIGNED((int)uap->addr, sizeof(int)))
 336                                 return (ERESTART);
 337 #undef  ALIGNED
 338 #endif
 339                         thread_setentrypoint(th_act, uap->addr);
 340                 }
 341
 342                 if ((unsigned)uap->data >= NSIG) {
 343                         error = EINVAL;
 344                         goto out;
 345                 }
 346
 347                 if (uap->data != 0) {
 348                         psignal(t, uap->data);
 349                 }
 350
 351                 if (uap->req == PT_STEP) {
 352                         /*
 353                          * set trace bit
 354                          */
 355                         if (thread_setsinglestep(th_act, 1) != KERN_SUCCESS) {
 356                                 error = ENOTSUP;
 357                                 goto out;
 358                         }
 359                 } else {
 360                         /*
 361                          * clear trace bit if on
 362                          */
 363                         if (thread_setsinglestep(th_act, 0) != KERN_SUCCESS) {
 364                                 error = ENOTSUP;
 365                                 goto out;
 366                         }
 367                 }
 368         resume:
 369                 proc_lock(t);
 370                 t->p_xstat = uap->data;
 371                 t->p_stat = SRUN;
 372                 if (t->sigwait) {
 373                         wakeup((caddr_t)&(t->sigwait));
 374                         proc_unlock(t);
 375                         if ((t->p_lflag & P_LSIGEXC) == 0) {
 376                                 task_resume(task);
 377                         }
 378                 } else
 379                         proc_unlock(t);
 380
 381                 break;
 382
 383         case PT_THUPDATE:  {
 384                 proc_unlock(t);
 385                 if ((unsigned)uap->data >= NSIG) {
 386                         error = EINVAL;
 387                         goto out;
 388                 }
 389                 th_act = port_name_to_thread(CAST_MACH_PORT_TO_NAME(uap->addr));
 390                 if (th_act == THREAD_NULL)
 391                         return (ESRCH);
 392                 ut = (uthread_t)get_bsdthread_info(th_act);
 393                 if (uap->data)
 394                         ut->uu_siglist |= sigmask(uap->data);
 395                 proc_lock(t);
 396                 t->p_xstat = uap->data;
 397                 t->p_stat = SRUN;
 398                 proc_unlock(t);
 399                 thread_deallocate(th_act);
 400                 error = 0;
 401                 }
 402                 break;
 403         default:
 404                 proc_unlock(t);
 405                 error = EINVAL;
 406                 goto out;
 407         }
 408
 409         error = 0;
 410 out:
 411         proc_rele(t);
 412         return(error);
 413 }
 414
 415
 416 /*
 417  * determine if one process (cur_procp) can trace another process (traced_procp).
 418  */
 419
 420 int
 421 cantrace(proc_t cur_procp, kauth_cred_t creds, proc_t traced_procp, int *errp)
 422 {
 423         int             my_err;
 424         /*
 425          * You can't trace a process if:
 426          *      (1) it's the process that's doing the tracing,
 427          */
 428         if (traced_procp->p_pid == cur_procp->p_pid) {
 429                 *errp = EINVAL;
 430                 return (0);
 431         }
 432
 433         /*
 434          *      (2) it's already being traced, or
 435          */
 436         if (ISSET(traced_procp->p_lflag, P_LTRACED)) {
 437                 *errp = EBUSY;
 438                 return (0);
 439         }
 440
 441         /*
 442          *      (3) it's not owned by you, or is set-id on exec
 443          *          (unless you're root).
 444          */
 445         if ((kauth_cred_getruid(creds) != kauth_cred_getruid(proc_ucred(traced_procp)) ||
 446                 ISSET(traced_procp->p_flag, P_SUGID)) &&
 447                 (my_err = suser(creds, &cur_procp->p_acflag)) != 0) {
 448                 *errp = my_err;
 449                 return (0);
 450         }
 451
 452         if ((cur_procp->p_lflag & P_LTRACED) && isinferior(cur_procp, traced_procp)) {
 453                 *errp = EPERM;
 454                 return (0);
 455         }
 456
 457         if (ISSET(traced_procp->p_lflag, P_LNOATTACH)) {
 458                 *errp = EBUSY;
 459                 return (0);
 460         }
 461         return(1);
 462 }