bsd/kern/mach_process.c

   1 /*
   2  * Copyright (c) 2000-2002 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 #include <mach/machine/thread_status.h>
  91
  92
  93 /* Macros to clear/set/test flags. */
  94 #define SET(t, f)       (t) |= (f)
  95 #define CLR(t, f)       (t) &= ~(f)
  96 #define ISSET(t, f)     ((t) & (f))
  97
  98 extern thread_t port_name_to_thread(mach_port_name_t port_name);
  99 extern kern_return_t thread_getstatus(thread_t thread, int flavor, thread_state_t tstate, mach_msg_type_number_t *count);
 100 extern thread_t get_firstthread(task_t);
 101
 102 #if defined (ppc)
 103 extern kern_return_t thread_setstatus(thread_t thread, int flavor, thread_state_t tstate, mach_msg_type_number_t count);
 104 #endif
 105
 106 /*
 107  * sys-trace system call.
 108  */
 109
 110 int
 111 ptrace(p, uap, retval)
 112         struct proc *p;
 113         struct ptrace_args *uap;
 114         register_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             *locr0;
 121 #if defined(ppc)
 122         struct ppc_thread_state64 statep;
 123 #elif   defined(i386)
 124         struct i386_saved_state statep;
 125 #else
 126 #error architecture not supported
 127 #endif
 128         unsigned long state_count;
 129         int tr_sigexc = 0;
 130
 131         AUDIT_ARG(cmd, uap->req);
 132         AUDIT_ARG(pid, uap->pid);
 133         AUDIT_ARG(addr, uap->addr);
 134         AUDIT_ARG(value, uap->data);
 135
 136         if (uap->req == PT_DENY_ATTACH) {
 137                 if (ISSET(p->p_flag, P_TRACED)) {
 138                         exit1(p, W_EXITCODE(ENOTSUP, 0), retval);
 139                         /* drop funnel before we return */
 140                         thread_funnel_set(kernel_flock, FALSE);
 141                         thread_exception_return();
 142                         /* NOTREACHED */
 143                 }
 144                 SET(p->p_flag, P_NOATTACH);
 145
 146                 return(0);
 147         }
 148
 149         if (uap->req == PT_FORCEQUOTA) {
 150                 if (is_suser()) {
 151                         SET(t->p_flag, P_FORCEQUOTA);
 152                         return (0);
 153                 } else
 154                         return (EPERM);
 155         }
 156
 157         /*
 158          *      Intercept and deal with "please trace me" request.
 159          */
 160         if (uap->req == PT_TRACE_ME) {
 161                 SET(p->p_flag, P_TRACED);
 162                 /* Non-attached case, our tracer is our parent. */
 163                 t->p_oppid = t->p_pptr->p_pid;
 164                 return(0);
 165         }
 166         if (uap->req == PT_SIGEXC) {
 167                 if (ISSET(p->p_flag, P_TRACED)) {
 168                         SET(p->p_flag, P_SIGEXC);
 169                         return(0);
 170                 } else
 171                         return(EINVAL);
 172         }
 173
 174         /*
 175          *      Locate victim, and make sure it is traceable.
 176          */
 177         if ((t = pfind(uap->pid)) == NULL)
 178                         return (ESRCH);
 179
 180         AUDIT_ARG(process, t);
 181
 182         /* We do not want ptrace to do anything with kernel, init
 183          * and mach_init
 184          */
 185         if (uap->pid <=2 )
 186                 return (EPERM);
 187
 188         task = t->task;
 189         if (uap->req == PT_ATTACHEXC) {
 190                 uap->req = PT_ATTACH;
 191                 tr_sigexc = 1;
 192         }
 193         if (uap->req == PT_ATTACH) {
 194                 int             err;
 195
 196                 if ( kauth_authorize_process(proc_ucred(p), KAUTH_PROCESS_CANTRACE,
 197                                                                          t, (uintptr_t)&err, 0, 0) == 0 ) {
 198                         /* it's OK to attach */
 199                         SET(t->p_flag, P_TRACED);
 200                         if (tr_sigexc)
 201                                 SET(t->p_flag, P_SIGEXC);
 202
 203                         t->p_oppid = t->p_pptr->p_pid;
 204                         if (t->p_pptr != p)
 205                                 proc_reparent(t, p);
 206
 207                         if (get_task_userstop(task) == 0 ) {
 208                                 t->p_xstat = 0;
 209                                 psignal(t, SIGSTOP);
 210                         } else {
 211                                 t->p_xstat = SIGSTOP;
 212                                 task_resume(task);
 213                         }
 214                         return(0);
 215                 }
 216                 else {
 217                         /* not allowed to attach, proper error code returned by kauth_authorize_process */
 218                         if (ISSET(t->p_flag, P_NOATTACH)) {
 219                                 psignal(p, SIGSEGV);
 220                         }
 221                         return (err);
 222                 }
 223         }
 224
 225         /*
 226          * You can't do what you want to the process if:
 227          *      (1) It's not being traced at all,
 228          */
 229         if (!ISSET(t->p_flag, P_TRACED))
 230                 return (EPERM);
 231
 232         /*
 233          *      (2) it's not being traced by _you_, or
 234          */
 235         if (t->p_pptr != p)
 236                 return (EBUSY);
 237
 238         /*
 239          *      (3) it's not currently stopped.
 240          */
 241         if (t->p_stat != SSTOP)
 242                 return (EBUSY);
 243
 244         /*
 245          *      Mach version of ptrace executes request directly here,
 246          *      thus simplifying the interaction of ptrace and signals.
 247          */
 248         switch (uap->req) {
 249
 250         case PT_DETACH:
 251                 if (t->p_oppid != t->p_pptr->p_pid) {
 252                         struct proc *pp;
 253
 254                         pp = pfind(t->p_oppid);
 255                         proc_reparent(t, pp ? pp : initproc);
 256                 }
 257
 258                 t->p_oppid = 0;
 259                 CLR(t->p_flag, P_TRACED);
 260                 CLR(t->p_flag, P_SIGEXC);
 261                 goto resume;
 262
 263         case PT_KILL:
 264                 /*
 265                  *      Tell child process to kill itself after it
 266                  *      is resumed by adding NSIG to p_cursig. [see issig]
 267                  */
 268                 psignal_lock(t, SIGKILL, 0);
 269                 goto resume;
 270
 271         case PT_STEP:                   /* single step the child */
 272         case PT_CONTINUE:               /* continue the child */
 273                 th_act = (thread_t)get_firstthread(task);
 274                 if (th_act == THREAD_NULL)
 275                         goto errorLabel;
 276                 ut = (uthread_t)get_bsdthread_info(th_act);
 277                 locr0 = ut->uu_ar0;
 278 #if defined(i386)
 279                 state_count = i386_NEW_THREAD_STATE_COUNT;
 280                 if (thread_getstatus(th_act, i386_NEW_THREAD_STATE, &statep, &state_count)  != KERN_SUCCESS) {
 281                         goto errorLabel;
 282                 }
 283 #elif defined(ppc)
 284                 state_count = PPC_THREAD_STATE64_COUNT;
 285                 if (thread_getstatus(th_act, PPC_THREAD_STATE64, (thread_state_t)&statep, (mach_msg_type_number_t *)&state_count)  != KERN_SUCCESS) {
 286                         goto errorLabel;
 287                 }
 288 #else
 289 #error architecture not supported
 290 #endif
 291                 if (uap->addr != (user_addr_t)1) {
 292 #if     defined(i386)
 293                         locr0[PC] = (int)uap->addr;
 294 #elif   defined(ppc)
 295 #define ALIGNED(addr,size)      (((unsigned)(addr)&((size)-1))==0)
 296                 if (!ALIGNED((int)uap->addr, sizeof(int)))
 297                         return (ERESTART);
 298
 299                 statep.srr0 = uap->addr;
 300                 state_count = PPC_THREAD_STATE64_COUNT;
 301                 if (thread_setstatus(th_act, PPC_THREAD_STATE64, (thread_state_t)&statep, state_count)  != KERN_SUCCESS) {
 302                         goto errorLabel;
 303                 }
 304 #undef  ALIGNED
 305 #else
 306 #error architecture not implemented!
 307 #endif
 308                 } /* uap->addr != (user_addr_t)1 */
 309
 310                 if ((unsigned)uap->data >= NSIG)
 311                         goto errorLabel;
 312
 313                 if (uap->data != 0) {
 314                         psignal_lock(t, uap->data, 0);
 315                 }
 316 #if defined(ppc)
 317                 state_count = PPC_THREAD_STATE64_COUNT;
 318                 if (thread_getstatus(th_act, PPC_THREAD_STATE64, (thread_state_t)&statep, (mach_msg_type_number_t *)&state_count)  != KERN_SUCCESS) {
 319                         goto errorLabel;
 320                 }
 321 #endif
 322
 323 #define MSR_SE_BIT      21
 324
 325                 if (uap->req == PT_STEP) {
 326 #if     defined(i386)
 327                         locr0[PS] |= PSL_T;
 328 #elif   defined(ppc)
 329                         statep.srr1 |= MASK(MSR_SE);
 330 #else
 331 #error architecture not implemented!
 332 #endif
 333                 } /* uap->req == PT_STEP */
 334                 else {  /* PT_CONTINUE - clear trace bit if set */
 335 #if defined(i386)
 336                         locr0[PS] &= ~PSL_T;
 337 #elif defined(ppc)
 338                         statep.srr1 &= ~MASK(MSR_SE);
 339 #endif
 340                 }
 341 #if defined (ppc)
 342                 state_count = PPC_THREAD_STATE64_COUNT;
 343                 if (thread_setstatus(th_act, PPC_THREAD_STATE64, (thread_state_t)&statep, state_count)  != KERN_SUCCESS) {
 344                         goto errorLabel;
 345                 }
 346 #endif
 347         resume:
 348                 t->p_xstat = uap->data;
 349                 t->p_stat = SRUN;
 350                 if (t->sigwait) {
 351                         wakeup((caddr_t)&(t->sigwait));
 352                         if ((t->p_flag & P_SIGEXC) == 0)
 353                                 task_release(task);
 354                 }
 355                 break;
 356
 357         case PT_THUPDATE:  {
 358                 if ((unsigned)uap->data >= NSIG)
 359                         goto errorLabel;
 360                 th_act = port_name_to_thread(CAST_DOWN(mach_port_name_t, uap->addr));
 361                 if (th_act == THREAD_NULL)
 362                         return (ESRCH);
 363                 ut = (uthread_t)get_bsdthread_info(th_act);
 364                 if (uap->data)
 365                         ut->uu_siglist |= sigmask(uap->data);
 366                 t->p_xstat = uap->data;
 367                 t->p_stat = SRUN;
 368                 thread_deallocate(th_act);
 369                 return(0);
 370                 }
 371                 break;
 372 errorLabel:
 373         default:
 374                 return(EINVAL);
 375         }
 376
 377         return(0);
 378 }
 379
 380
 381 /*
 382  * determine if one process (cur_procp) can trace another process (traced_procp).
 383  */
 384
 385 int
 386 cantrace(proc_t cur_procp, kauth_cred_t creds, proc_t traced_procp, int *errp)
 387 {
 388         int             my_err;
 389         /*
 390          * You can't trace a process if:
 391          *      (1) it's the process that's doing the tracing,
 392          */
 393         if (traced_procp->p_pid == cur_procp->p_pid) {
 394                 *errp = EINVAL;
 395                 return (0);
 396         }
 397
 398         /*
 399          *      (2) it's already being traced, or
 400          */
 401         if (ISSET(traced_procp->p_flag, P_TRACED)) {
 402                 *errp = EBUSY;
 403                 return (0);
 404         }
 405
 406         /*
 407          *      (3) it's not owned by you, or is set-id on exec
 408          *          (unless you're root).
 409          */
 410         if ((creds->cr_ruid != proc_ucred(traced_procp)->cr_ruid ||
 411                 ISSET(traced_procp->p_flag, P_SUGID)) &&
 412                 (my_err = suser(creds, &cur_procp->p_acflag)) != 0) {
 413                 *errp = my_err;
 414                 return (0);
 415         }
 416
 417         if ((cur_procp->p_flag & P_TRACED) && isinferior(cur_procp, traced_procp)) {
 418                 *errp = EPERM;
 419                 return (0);
 420         }
 421
 422         if (ISSET(traced_procp->p_flag, P_NOATTACH)) {
 423                 *errp = EBUSY;
 424                 return (0);
 425         }
 426         return(1);
 427 }