bsd/kern/mach_process.c

   1 /*
   2  * Copyright (c) 2006 Apple Computer, Inc. All Rights Reserved.
   3  *
   4  * @APPLE_LICENSE_OSREFERENCE_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
  10  * License may not be used to create, or enable the creation or
  11  * redistribution of, unlawful or unlicensed copies of an Apple operating
  12  * system, or to circumvent, violate, or enable the circumvention or
  13  * violation of, any terms of an Apple operating system software license
  14  * agreement.
  15  *
  16  * Please obtain a copy of the License at
  17  * http://www.opensource.apple.com/apsl/ and read it before using this
  18  * file.
  19  *
  20  * The Original Code and all software distributed under the License are
  21  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  22  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  23  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  24  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  25  * Please see the License for the specific language governing rights and
  26  * limitations under the License.
  27  *
  28  * @APPLE_LICENSE_OSREFERENCE_HEADER_END@
  29  */
  30 /* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */
  31 /*-
  32  * Copyright (c) 1982, 1986, 1989, 1993
  33  *      The Regents of the University of California.  All rights reserved.
  34  * (c) UNIX System Laboratories, Inc.
  35  * All or some portions of this file are derived from material licensed
  36  * to the University of California by American Telephone and Telegraph
  37  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
  38  * the permission of UNIX System Laboratories, Inc.
  39  *
  40  * Redistribution and use in source and binary forms, with or without
  41  * modification, are permitted provided that the following conditions
  42  * are met:
  43  * 1. Redistributions of source code must retain the above copyright
  44  *    notice, this list of conditions and the following disclaimer.
  45  * 2. Redistributions in binary form must reproduce the above copyright
  46  *    notice, this list of conditions and the following disclaimer in the
  47  *    documentation and/or other materials provided with the distribution.
  48  * 3. All advertising materials mentioning features or use of this software
  49  *    must display the following acknowledgement:
  50  *      This product includes software developed by the University of
  51  *      California, Berkeley and its contributors.
  52  * 4. Neither the name of the University nor the names of its contributors
  53  *    may be used to endorse or promote products derived from this software
  54  *    without specific prior written permission.
  55  *
  56  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  57  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  58  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  59  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  60  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  61  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  62  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  63  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  64  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  65  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  66  * SUCH DAMAGE.
  67  *
  68  *      from: @(#)sys_process.c 8.1 (Berkeley) 6/10/93
  69  */
  70
  71 #include <machine/reg.h>
  72 #include <machine/psl.h>
  73
  74 #include <sys/param.h>
  75 #include <sys/systm.h>
  76 #include <sys/proc_internal.h>
  77 #include <sys/kauth.h>
  78 #include <sys/errno.h>
  79 #include <sys/ptrace.h>
  80 #include <sys/uio.h>
  81 #include <sys/user.h>
  82 #include <sys/sysctl.h>
  83 #include <sys/wait.h>
  84
  85 #include <sys/mount_internal.h>
  86 #include <sys/sysproto.h>
  87
  88 #include <bsm/audit_kernel.h>
  89
  90 #include <kern/task.h>
  91 #include <kern/thread.h>
  92 #include <mach/machine/thread_status.h>
  93
  94
  95 /* Macros to clear/set/test flags. */
  96 #define SET(t, f)       (t) |= (f)
  97 #define CLR(t, f)       (t) &= ~(f)
  98 #define ISSET(t, f)     ((t) & (f))
  99
 100 extern thread_t port_name_to_thread(mach_port_name_t port_name);
 101 extern kern_return_t thread_getstatus(thread_t thread, int flavor, thread_state_t tstate, mach_msg_type_number_t *count);
 102 extern thread_t get_firstthread(task_t);
 103
 104 #if defined (ppc)
 105 extern kern_return_t thread_setstatus(thread_t thread, int flavor, thread_state_t tstate, mach_msg_type_number_t count);
 106 #endif
 107
 108 /*
 109  * sys-trace system call.
 110  */
 111
 112 int
 113 ptrace(p, uap, retval)
 114         struct proc *p;
 115         struct ptrace_args *uap;
 116         register_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             *locr0;
 123 #if defined(ppc)
 124         struct ppc_thread_state64 statep;
 125 #elif   defined(i386)
 126         struct i386_saved_state statep;
 127 #else
 128 #error architecture not supported
 129 #endif
 130         unsigned long state_count;
 131         int tr_sigexc = 0;
 132
 133         AUDIT_ARG(cmd, uap->req);
 134         AUDIT_ARG(pid, uap->pid);
 135         AUDIT_ARG(addr, uap->addr);
 136         AUDIT_ARG(value, uap->data);
 137
 138         if (uap->req == PT_DENY_ATTACH) {
 139                 if (ISSET(p->p_flag, P_TRACED)) {
 140                         exit1(p, W_EXITCODE(ENOTSUP, 0), retval);
 141                         /* drop funnel before we return */
 142                         thread_funnel_set(kernel_flock, FALSE);
 143                         thread_exception_return();
 144                         /* NOTREACHED */
 145                 }
 146                 SET(p->p_flag, P_NOATTACH);
 147
 148                 return(0);
 149         }
 150
 151         if (uap->req == PT_FORCEQUOTA) {
 152                 if (is_suser()) {
 153                         SET(t->p_flag, P_FORCEQUOTA);
 154                         return (0);
 155                 } else
 156                         return (EPERM);
 157         }
 158
 159         /*
 160          *      Intercept and deal with "please trace me" request.
 161          */
 162         if (uap->req == PT_TRACE_ME) {
 163                 SET(p->p_flag, P_TRACED);
 164                 /* Non-attached case, our tracer is our parent. */
 165                 t->p_oppid = t->p_pptr->p_pid;
 166                 return(0);
 167         }
 168         if (uap->req == PT_SIGEXC) {
 169                 if (ISSET(p->p_flag, P_TRACED)) {
 170                         SET(p->p_flag, P_SIGEXC);
 171                         return(0);
 172                 } else
 173                         return(EINVAL);
 174         }
 175
 176         /*
 177          *      Locate victim, and make sure it is traceable.
 178          */
 179         if ((t = pfind(uap->pid)) == NULL)
 180                         return (ESRCH);
 181
 182         AUDIT_ARG(process, t);
 183
 184         /* We do not want ptrace to do anything with kernel, init
 185          * and mach_init
 186          */
 187         if (uap->pid <=2 )
 188                 return (EPERM);
 189
 190         task = t->task;
 191         if (uap->req == PT_ATTACHEXC) {
 192                 uap->req = PT_ATTACH;
 193                 tr_sigexc = 1;
 194         }
 195         if (uap->req == PT_ATTACH) {
 196                 int             err;
 197
 198                 if ( kauth_authorize_process(proc_ucred(p), KAUTH_PROCESS_CANTRACE,
 199                                                                          t, (uintptr_t)&err, 0, 0) == 0 ) {
 200                         /* it's OK to attach */
 201                         SET(t->p_flag, P_TRACED);
 202                         if (tr_sigexc)
 203                                 SET(t->p_flag, P_SIGEXC);
 204
 205                         t->p_oppid = t->p_pptr->p_pid;
 206                         if (t->p_pptr != p)
 207                                 proc_reparent(t, p);
 208
 209                         if (get_task_userstop(task) == 0 ) {
 210                                 t->p_xstat = 0;
 211                                 psignal(t, SIGSTOP);
 212                         } else {
 213                                 t->p_xstat = SIGSTOP;
 214                                 task_resume(task);
 215                         }
 216                         return(0);
 217                 }
 218                 else {
 219                         /* not allowed to attach, proper error code returned by kauth_authorize_process */
 220                         if (ISSET(t->p_flag, P_NOATTACH)) {
 221                                 psignal(p, SIGSEGV);
 222                         }
 223                         return (err);
 224                 }
 225         }
 226
 227         /*
 228          * You can't do what you want to the process if:
 229          *      (1) It's not being traced at all,
 230          */
 231         if (!ISSET(t->p_flag, P_TRACED))
 232                 return (EPERM);
 233
 234         /*
 235          *      (2) it's not being traced by _you_, or
 236          */
 237         if (t->p_pptr != p)
 238                 return (EBUSY);
 239
 240         /*
 241          *      (3) it's not currently stopped.
 242          */
 243         if (t->p_stat != SSTOP)
 244                 return (EBUSY);
 245
 246         /*
 247          *      Mach version of ptrace executes request directly here,
 248          *      thus simplifying the interaction of ptrace and signals.
 249          */
 250         switch (uap->req) {
 251
 252         case PT_DETACH:
 253                 if (t->p_oppid != t->p_pptr->p_pid) {
 254                         struct proc *pp;
 255
 256                         pp = pfind(t->p_oppid);
 257                         proc_reparent(t, pp ? pp : initproc);
 258                 }
 259
 260                 t->p_oppid = 0;
 261                 CLR(t->p_flag, P_TRACED);
 262                 CLR(t->p_flag, P_SIGEXC);
 263                 goto resume;
 264
 265         case PT_KILL:
 266                 /*
 267                  *      Tell child process to kill itself after it
 268                  *      is resumed by adding NSIG to p_cursig. [see issig]
 269                  */
 270                 psignal_lock(t, SIGKILL, 0);
 271                 goto resume;
 272
 273         case PT_STEP:                   /* single step the child */
 274         case PT_CONTINUE:               /* continue the child */
 275                 th_act = (thread_t)get_firstthread(task);
 276                 if (th_act == THREAD_NULL)
 277                         goto errorLabel;
 278                 ut = (uthread_t)get_bsdthread_info(th_act);
 279                 locr0 = ut->uu_ar0;
 280 #if defined(i386)
 281                 state_count = i386_NEW_THREAD_STATE_COUNT;
 282                 if (thread_getstatus(th_act, i386_NEW_THREAD_STATE, &statep, &state_count)  != KERN_SUCCESS) {
 283                         goto errorLabel;
 284                 }
 285 #elif defined(ppc)
 286                 state_count = PPC_THREAD_STATE64_COUNT;
 287                 if (thread_getstatus(th_act, PPC_THREAD_STATE64, (thread_state_t)&statep, (mach_msg_type_number_t *)&state_count)  != KERN_SUCCESS) {
 288                         goto errorLabel;
 289                 }
 290 #else
 291 #error architecture not supported
 292 #endif
 293                 if (uap->addr != (user_addr_t)1) {
 294 #if     defined(i386)
 295                         locr0[PC] = (int)uap->addr;
 296 #elif   defined(ppc)
 297 #define ALIGNED(addr,size)      (((unsigned)(addr)&((size)-1))==0)
 298                 if (!ALIGNED((int)uap->addr, sizeof(int)))
 299                         return (ERESTART);
 300
 301                 statep.srr0 = uap->addr;
 302                 state_count = PPC_THREAD_STATE64_COUNT;
 303                 if (thread_setstatus(th_act, PPC_THREAD_STATE64, (thread_state_t)&statep, state_count)  != KERN_SUCCESS) {
 304                         goto errorLabel;
 305                 }
 306 #undef  ALIGNED
 307 #else
 308 #error architecture not implemented!
 309 #endif
 310                 } /* uap->addr != (user_addr_t)1 */
 311
 312                 if ((unsigned)uap->data >= NSIG)
 313                         goto errorLabel;
 314
 315                 if (uap->data != 0) {
 316                         psignal_lock(t, uap->data, 0);
 317                 }
 318 #if defined(ppc)
 319                 state_count = PPC_THREAD_STATE64_COUNT;
 320                 if (thread_getstatus(th_act, PPC_THREAD_STATE64, (thread_state_t)&statep, (mach_msg_type_number_t *)&state_count)  != KERN_SUCCESS) {
 321                         goto errorLabel;
 322                 }
 323 #endif
 324
 325 #define MSR_SE_BIT      21
 326
 327                 if (uap->req == PT_STEP) {
 328 #if     defined(i386)
 329                         locr0[PS] |= PSL_T;
 330 #elif   defined(ppc)
 331                         statep.srr1 |= MASK(MSR_SE);
 332 #else
 333 #error architecture not implemented!
 334 #endif
 335                 } /* uap->req == PT_STEP */
 336                 else {  /* PT_CONTINUE - clear trace bit if set */
 337 #if defined(i386)
 338                         locr0[PS] &= ~PSL_T;
 339 #elif defined(ppc)
 340                         statep.srr1 &= ~MASK(MSR_SE);
 341 #endif
 342                 }
 343 #if defined (ppc)
 344                 state_count = PPC_THREAD_STATE64_COUNT;
 345                 if (thread_setstatus(th_act, PPC_THREAD_STATE64, (thread_state_t)&statep, state_count)  != KERN_SUCCESS) {
 346                         goto errorLabel;
 347                 }
 348 #endif
 349         resume:
 350                 t->p_xstat = uap->data;
 351                 t->p_stat = SRUN;
 352                 if (t->sigwait) {
 353                         wakeup((caddr_t)&(t->sigwait));
 354                         if ((t->p_flag & P_SIGEXC) == 0)
 355                                 task_release(task);
 356                 }
 357                 break;
 358
 359         case PT_THUPDATE:  {
 360                 if ((unsigned)uap->data >= NSIG)
 361                         goto errorLabel;
 362                 th_act = port_name_to_thread(CAST_DOWN(mach_port_name_t, uap->addr));
 363                 if (th_act == THREAD_NULL)
 364                         return (ESRCH);
 365                 ut = (uthread_t)get_bsdthread_info(th_act);
 366                 if (uap->data)
 367                         ut->uu_siglist |= sigmask(uap->data);
 368                 t->p_xstat = uap->data;
 369                 t->p_stat = SRUN;
 370                 thread_deallocate(th_act);
 371                 return(0);
 372                 }
 373                 break;
 374 errorLabel:
 375         default:
 376                 return(EINVAL);
 377         }
 378
 379         return(0);
 380 }
 381
 382
 383 /*
 384  * determine if one process (cur_procp) can trace another process (traced_procp).
 385  */
 386
 387 int
 388 cantrace(proc_t cur_procp, kauth_cred_t creds, proc_t traced_procp, int *errp)
 389 {
 390         int             my_err;
 391         /*
 392          * You can't trace a process if:
 393          *      (1) it's the process that's doing the tracing,
 394          */
 395         if (traced_procp->p_pid == cur_procp->p_pid) {
 396                 *errp = EINVAL;
 397                 return (0);
 398         }
 399
 400         /*
 401          *      (2) it's already being traced, or
 402          */
 403         if (ISSET(traced_procp->p_flag, P_TRACED)) {
 404                 *errp = EBUSY;
 405                 return (0);
 406         }
 407
 408         /*
 409          *      (3) it's not owned by you, or is set-id on exec
 410          *          (unless you're root).
 411          */
 412         if ((creds->cr_ruid != proc_ucred(traced_procp)->cr_ruid ||
 413                 ISSET(traced_procp->p_flag, P_SUGID)) &&
 414                 (my_err = suser(creds, &cur_procp->p_acflag)) != 0) {
 415                 *errp = my_err;
 416                 return (0);
 417         }
 418
 419         if ((cur_procp->p_flag & P_TRACED) && isinferior(cur_procp, traced_procp)) {
 420                 *errp = EPERM;
 421                 return (0);
 422         }
 423
 424         if (ISSET(traced_procp->p_flag, P_NOATTACH)) {
 425                 *errp = EBUSY;
 426                 return (0);
 427         }
 428         return(1);
 429 }