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
  86 #include <bsm/audit_kernel.h>
  87
  88 #include <kern/task.h>
  89 #include <kern/thread.h>
  90
  91 #include <mach/task.h>                  /* for task_resume() */
  92 #include <kern/sched_prim.h>            /* for thread_exception_return() */
  93
  94 /* XXX ken/bsd_kern.c - prototype should be in common header */
  95 int get_task_userstop(task_t);
  96
  97 /* Macros to clear/set/test flags. */
  98 #define SET(t, f)       (t) |= (f)
  99 #define CLR(t, f)       (t) &= ~(f)
 100 #define ISSET(t, f)     ((t) & (f))
 101
 102 extern thread_t port_name_to_thread(mach_port_name_t port_name);
 103 extern thread_t get_firstthread(task_t);
 104
 105
 106 /*
 107  * sys-trace system call.
 108  */
 109
 110 int
 111 ptrace(struct proc *p, struct ptrace_args *uap, register_t *retval)
 112 {
 113         struct proc *t = current_proc();        /* target process */
 114         task_t          task;
 115         thread_t        th_act;
 116         struct uthread  *ut;
 117         int tr_sigexc = 0;
 118         int error = 0;
 119         int stopped = 0;
 120
 121         AUDIT_ARG(cmd, uap->req);
 122         AUDIT_ARG(pid, uap->pid);
 123         AUDIT_ARG(addr, uap->addr);
 124         AUDIT_ARG(value, uap->data);
 125
 126         if (uap->req == PT_DENY_ATTACH) {
 127                 proc_lock(p);
 128                 if (ISSET(p->p_lflag, P_LTRACED)) {
 129                         proc_unlock(p);
 130                         exit1(p, W_EXITCODE(ENOTSUP, 0), retval);
 131                         /* drop funnel before we return */
 132                         thread_exception_return();
 133                         /* NOTREACHED */
 134                 }
 135                 SET(p->p_lflag, P_LNOATTACH);
 136                 proc_unlock(p);
 137
 138                 return(0);
 139         }
 140
 141         if (uap->req == PT_FORCEQUOTA) {
 142                 if (is_suser()) {
 143                         OSBitOrAtomic(P_FORCEQUOTA, (UInt32 *)&t->p_flag);
 144                         return (0);
 145                 } else
 146                         return (EPERM);
 147         }
 148
 149         /*
 150          *      Intercept and deal with "please trace me" request.
 151          */
 152         if (uap->req == PT_TRACE_ME) {
 153                 proc_lock(p);
 154                 SET(p->p_lflag, P_LTRACED);
 155                 /* Non-attached case, our tracer is our parent. */
 156                 p->p_oppid = p->p_ppid;
 157                 proc_unlock(p);
 158                 return(0);
 159         }
 160         if (uap->req == PT_SIGEXC) {
 161                 proc_lock(p);
 162                 if (ISSET(p->p_lflag, P_LTRACED)) {
 163                         SET(p->p_lflag, P_LSIGEXC);
 164                         proc_unlock(p);
 165                         return(0);
 166                 } else {
 167                         proc_unlock(p);
 168                         return(EINVAL);
 169                 }
 170         }
 171
 172         /*
 173          * We do not want ptrace to do anything with kernel or launchd
 174          */
 175         if (uap->pid < 2) {
 176                 return(EPERM);
 177         }
 178
 179         /*
 180          *      Locate victim, and make sure it is traceable.
 181          */
 182         if ((t = proc_find(uap->pid)) == NULL)
 183                         return (ESRCH);
 184
 185         AUDIT_ARG(process, t);
 186
 187         task = t->task;
 188         if (uap->req == PT_ATTACHEXC) {
 189                 uap->req = PT_ATTACH;
 190                 tr_sigexc = 1;
 191         }
 192         if (uap->req == PT_ATTACH) {
 193                 int             err;
 194
 195                 if ( kauth_authorize_process(proc_ucred(p), KAUTH_PROCESS_CANTRACE,
 196                                                                          t, (uintptr_t)&err, 0, 0) == 0 ) {
 197                         /* it's OK to attach */
 198                         proc_lock(t);
 199                         SET(t->p_lflag, P_LTRACED);
 200                         if (tr_sigexc)
 201                                 SET(t->p_lflag, P_LSIGEXC);
 202
 203                         t->p_oppid = t->p_ppid;
 204                         proc_unlock(t);
 205                         if (t->p_pptr != p)
 206                                 proc_reparentlocked(t, p, 1, 0);
 207
 208                         proc_lock(t);
 209                         if (get_task_userstop(task) > 0 ) {
 210                                 stopped = 1;
 211                         }
 212                         t->p_xstat = 0;
 213                         proc_unlock(t);
 214                         psignal(t, SIGSTOP);
 215                         /*
 216                          * If the process was stopped, wake up and run through
 217                          * issignal() again to properly connect to the tracing
 218                          * process.
 219                          */
 220                         if (stopped)
 221                                 task_resume(task);
 222                         error = 0;
 223                         goto out;
 224                 }
 225                 else {
 226                         /* not allowed to attach, proper error code returned by kauth_authorize_process */
 227                         if (ISSET(t->p_lflag, P_LNOATTACH)) {
 228                                 psignal(p, SIGSEGV);
 229                         }
 230
 231                         error = err;
 232                         goto out;
 233                 }
 234         }
 235
 236         /*
 237          * You can't do what you want to the process if:
 238          *      (1) It's not being traced at all,
 239          */
 240         proc_lock(t);
 241         if (!ISSET(t->p_lflag, P_LTRACED)) {
 242                 proc_unlock(t);
 243                 error = EPERM;
 244                 goto out;
 245         }
 246
 247         /*
 248          *      (2) it's not being traced by _you_, or
 249          */
 250         if (t->p_pptr != p) {
 251                 proc_unlock(t);
 252                 error = EBUSY;
 253                 goto out;
 254         }
 255
 256         /*
 257          *      (3) it's not currently stopped.
 258          */
 259         if (t->p_stat != SSTOP) {
 260                 proc_unlock(t);
 261                 error = EBUSY;
 262                 goto out;
 263         }
 264
 265         /*
 266          *      Mach version of ptrace executes request directly here,
 267          *      thus simplifying the interaction of ptrace and signals.
 268          */
 269         /* proc lock is held here */
 270         switch (uap->req) {
 271
 272         case PT_DETACH:
 273                 if (t->p_oppid != t->p_ppid) {
 274                         struct proc *pp;
 275
 276                         proc_unlock(t);
 277                         pp = proc_find(t->p_oppid);
 278                         proc_reparentlocked(t, pp ? pp : initproc, 1, 0);
 279                         if (pp != PROC_NULL)
 280                                 proc_rele(pp);
 281                         proc_lock(t);
 282
 283                 }
 284
 285                 t->p_oppid = 0;
 286                 CLR(t->p_lflag, P_LTRACED);
 287                 CLR(t->p_lflag, P_LSIGEXC);
 288                 proc_unlock(t);
 289                 goto resume;
 290
 291         case PT_KILL:
 292                 /*
 293                  *      Tell child process to kill itself after it
 294                  *      is resumed by adding NSIG to p_cursig. [see issig]
 295                  */
 296                 proc_unlock(t);
 297                 psignal(t, SIGKILL);
 298                 goto resume;
 299
 300         case PT_STEP:                   /* single step the child */
 301         case PT_CONTINUE:               /* continue the child */
 302                 proc_unlock(t);
 303                 th_act = (thread_t)get_firstthread(task);
 304                 if (th_act == THREAD_NULL) {
 305                         error = EINVAL;
 306                         goto out;
 307                 }
 308
 309                 if (uap->addr != (user_addr_t)1) {
 310 #if defined(ppc)
 311 #define ALIGNED(addr,size)      (((unsigned)(addr)&((size)-1))==0)
 312                         if (!ALIGNED((int)uap->addr, sizeof(int)))
 313                                 return (ERESTART);
 314 #undef  ALIGNED
 315 #endif
 316                         thread_setentrypoint(th_act, uap->addr);
 317                 }
 318
 319                 if ((unsigned)uap->data >= NSIG) {
 320                         error = EINVAL;
 321                         goto out;
 322                 }
 323
 324                 if (uap->data != 0) {
 325                         psignal(t, uap->data);
 326                 }
 327
 328                 if (uap->req == PT_STEP) {
 329                         /*
 330                          * set trace bit
 331                          */
 332                         if (thread_setsinglestep(th_act, 1) != KERN_SUCCESS) {
 333                                 error = ENOTSUP;
 334                                 goto out;
 335                         }
 336                 } else {
 337                         /*
 338                          * clear trace bit if on
 339                          */
 340                         if (thread_setsinglestep(th_act, 0) != KERN_SUCCESS) {
 341                                 error = ENOTSUP;
 342                                 goto out;
 343                         }
 344                 }
 345         resume:
 346                 proc_lock(t);
 347                 t->p_xstat = uap->data;
 348                 t->p_stat = SRUN;
 349                 if (t->sigwait) {
 350                         wakeup((caddr_t)&(t->sigwait));
 351                         proc_unlock(t);
 352                         if ((t->p_lflag & P_LSIGEXC) == 0) {
 353                                 task_resume(task);
 354                         }
 355                 } else
 356                         proc_unlock(t);
 357
 358                 break;
 359
 360         case PT_THUPDATE:  {
 361                 proc_unlock(t);
 362                 if ((unsigned)uap->data >= NSIG) {
 363                         error = EINVAL;
 364                         goto out;
 365                 }
 366                 th_act = port_name_to_thread(CAST_DOWN(mach_port_name_t, uap->addr));
 367                 if (th_act == THREAD_NULL)
 368                         return (ESRCH);
 369                 ut = (uthread_t)get_bsdthread_info(th_act);
 370                 if (uap->data)
 371                         ut->uu_siglist |= sigmask(uap->data);
 372                 proc_lock(t);
 373                 t->p_xstat = uap->data;
 374                 t->p_stat = SRUN;
 375                 proc_unlock(t);
 376                 thread_deallocate(th_act);
 377                 error = 0;
 378                 }
 379                 break;
 380         default:
 381                 proc_unlock(t);
 382                 error = EINVAL;
 383                 goto out;
 384         }
 385
 386         error = 0;
 387 out:
 388         proc_rele(t);
 389         return(error);
 390 }
 391
 392
 393 /*
 394  * determine if one process (cur_procp) can trace another process (traced_procp).
 395  */
 396
 397 int
 398 cantrace(proc_t cur_procp, kauth_cred_t creds, proc_t traced_procp, int *errp)
 399 {
 400         int             my_err;
 401         /*
 402          * You can't trace a process if:
 403          *      (1) it's the process that's doing the tracing,
 404          */
 405         if (traced_procp->p_pid == cur_procp->p_pid) {
 406                 *errp = EINVAL;
 407                 return (0);
 408         }
 409
 410         /*
 411          *      (2) it's already being traced, or
 412          */
 413         if (ISSET(traced_procp->p_lflag, P_LTRACED)) {
 414                 *errp = EBUSY;
 415                 return (0);
 416         }
 417
 418         /*
 419          *      (3) it's not owned by you, or is set-id on exec
 420          *          (unless you're root).
 421          */
 422         if ((creds->cr_ruid != proc_ucred(traced_procp)->cr_ruid ||
 423                 ISSET(traced_procp->p_flag, P_SUGID)) &&
 424                 (my_err = suser(creds, &cur_procp->p_acflag)) != 0) {
 425                 *errp = my_err;
 426                 return (0);
 427         }
 428
 429         if ((cur_procp->p_lflag & P_LTRACED) && isinferior(cur_procp, traced_procp)) {
 430                 *errp = EPERM;
 431                 return (0);
 432         }
 433
 434         if (ISSET(traced_procp->p_lflag, P_LNOATTACH)) {
 435                 *errp = EBUSY;
 436                 return (0);
 437         }
 438         return(1);
 439 }