bsd/kern/mach_process.c

   1 /*
   2  * Copyright (c) 2000-2002 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_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. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23 /* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */
  24 /*-
  25  * Copyright (c) 1982, 1986, 1989, 1993
  26  *      The Regents of the University of California.  All rights reserved.
  27  * (c) UNIX System Laboratories, Inc.
  28  * All or some portions of this file are derived from material licensed
  29  * to the University of California by American Telephone and Telegraph
  30  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
  31  * the permission of UNIX System Laboratories, Inc.
  32  *
  33  * Redistribution and use in source and binary forms, with or without
  34  * modification, are permitted provided that the following conditions
  35  * are met:
  36  * 1. Redistributions of source code must retain the above copyright
  37  *    notice, this list of conditions and the following disclaimer.
  38  * 2. Redistributions in binary form must reproduce the above copyright
  39  *    notice, this list of conditions and the following disclaimer in the
  40  *    documentation and/or other materials provided with the distribution.
  41  * 3. All advertising materials mentioning features or use of this software
  42  *    must display the following acknowledgement:
  43  *      This product includes software developed by the University of
  44  *      California, Berkeley and its contributors.
  45  * 4. Neither the name of the University nor the names of its contributors
  46  *    may be used to endorse or promote products derived from this software
  47  *    without specific prior written permission.
  48  *
  49  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  50  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  51  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  52  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  53  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  54  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  55  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  56  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  57  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  58  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  59  * SUCH DAMAGE.
  60  *
  61  *      from: @(#)sys_process.c 8.1 (Berkeley) 6/10/93
  62  */
  63
  64 #include <machine/reg.h>
  65 #include <machine/psl.h>
  66
  67 #include <sys/param.h>
  68 #include <sys/systm.h>
  69 #include <sys/proc_internal.h>
  70 #include <sys/kauth.h>
  71 #include <sys/errno.h>
  72 #include <sys/ptrace.h>
  73 #include <sys/uio.h>
  74 #include <sys/user.h>
  75 #include <sys/sysctl.h>
  76 #include <sys/wait.h>
  77
  78 #include <sys/mount_internal.h>
  79 #include <sys/sysproto.h>
  80
  81 #include <bsm/audit_kernel.h>
  82
  83 #include <kern/task.h>
  84 #include <kern/thread.h>
  85 #include <mach/machine/thread_status.h>
  86
  87
  88 /* Macros to clear/set/test flags. */
  89 #define SET(t, f)       (t) |= (f)
  90 #define CLR(t, f)       (t) &= ~(f)
  91 #define ISSET(t, f)     ((t) & (f))
  92
  93 extern thread_t port_name_to_thread(mach_port_name_t port_name);
  94 extern kern_return_t thread_getstatus(thread_t thread, int flavor, thread_state_t tstate, mach_msg_type_number_t *count);
  95 extern thread_t get_firstthread(task_t);
  96
  97 #if defined (ppc)
  98 extern kern_return_t thread_setstatus(thread_t thread, int flavor, thread_state_t tstate, mach_msg_type_number_t count);
  99 #endif
 100
 101 /*
 102  * sys-trace system call.
 103  */
 104
 105 int
 106 ptrace(p, uap, retval)
 107         struct proc *p;
 108         struct ptrace_args *uap;
 109         register_t *retval;
 110 {
 111         struct proc *t = current_proc();        /* target process */
 112         task_t          task;
 113         thread_t        th_act;
 114         struct uthread  *ut;
 115         int             *locr0;
 116 #if defined(ppc)
 117         struct ppc_thread_state64 statep;
 118 #elif   defined(i386)
 119         struct i386_saved_state statep;
 120 #else
 121 #error architecture not supported
 122 #endif
 123         unsigned long state_count;
 124         int tr_sigexc = 0;
 125
 126         AUDIT_ARG(cmd, uap->req);
 127         AUDIT_ARG(pid, uap->pid);
 128         AUDIT_ARG(addr, uap->addr);
 129         AUDIT_ARG(value, uap->data);
 130
 131         if (uap->req == PT_DENY_ATTACH) {
 132                 if (ISSET(p->p_flag, P_TRACED)) {
 133                         exit1(p, W_EXITCODE(ENOTSUP, 0), retval);
 134                         /* drop funnel before we return */
 135                         thread_funnel_set(kernel_flock, FALSE);
 136                         thread_exception_return();
 137                         /* NOTREACHED */
 138                 }
 139                 SET(p->p_flag, P_NOATTACH);
 140
 141                 return(0);
 142         }
 143
 144         if (uap->req == PT_FORCEQUOTA) {
 145                 if (is_suser()) {
 146                         SET(t->p_flag, P_FORCEQUOTA);
 147                         return (0);
 148                 } else
 149                         return (EPERM);
 150         }
 151
 152         /*
 153          *      Intercept and deal with "please trace me" request.
 154          */
 155         if (uap->req == PT_TRACE_ME) {
 156                 SET(p->p_flag, P_TRACED);
 157                 /* Non-attached case, our tracer is our parent. */
 158                 t->p_oppid = t->p_pptr->p_pid;
 159                 return(0);
 160         }
 161         if (uap->req == PT_SIGEXC) {
 162                 if (ISSET(p->p_flag, P_TRACED)) {
 163                         SET(p->p_flag, P_SIGEXC);
 164                         return(0);
 165                 } else
 166                         return(EINVAL);
 167         }
 168
 169         /*
 170          *      Locate victim, and make sure it is traceable.
 171          */
 172         if ((t = pfind(uap->pid)) == NULL)
 173                         return (ESRCH);
 174
 175         AUDIT_ARG(process, t);
 176
 177         /* We do not want ptrace to do anything with kernel, init
 178          * and mach_init
 179          */
 180         if (uap->pid <=2 )
 181                 return (EPERM);
 182
 183         task = t->task;
 184         if (uap->req == PT_ATTACHEXC) {
 185                 uap->req = PT_ATTACH;
 186                 tr_sigexc = 1;
 187         }
 188         if (uap->req == PT_ATTACH) {
 189                 int             err;
 190
 191                 if ( kauth_authorize_process(proc_ucred(p), KAUTH_PROCESS_CANTRACE,
 192                                                                          t, (uintptr_t)&err, 0, 0) == 0 ) {
 193                         /* it's OK to attach */
 194                         SET(t->p_flag, P_TRACED);
 195                         if (tr_sigexc)
 196                                 SET(t->p_flag, P_SIGEXC);
 197
 198                         t->p_oppid = t->p_pptr->p_pid;
 199                         if (t->p_pptr != p)
 200                                 proc_reparent(t, p);
 201
 202                         if (get_task_userstop(task) == 0 ) {
 203                                 t->p_xstat = 0;
 204                                 psignal(t, SIGSTOP);
 205                         } else {
 206                                 t->p_xstat = SIGSTOP;
 207                                 task_resume(task);
 208                         }
 209                         return(0);
 210                 }
 211                 else {
 212                         /* not allowed to attach, proper error code returned by kauth_authorize_process */
 213                         if (ISSET(t->p_flag, P_NOATTACH)) {
 214                                 psignal(p, SIGSEGV);
 215                         }
 216                         return (err);
 217                 }
 218         }
 219
 220         /*
 221          * You can't do what you want to the process if:
 222          *      (1) It's not being traced at all,
 223          */
 224         if (!ISSET(t->p_flag, P_TRACED))
 225                 return (EPERM);
 226
 227         /*
 228          *      (2) it's not being traced by _you_, or
 229          */
 230         if (t->p_pptr != p)
 231                 return (EBUSY);
 232
 233         /*
 234          *      (3) it's not currently stopped.
 235          */
 236         if (t->p_stat != SSTOP)
 237                 return (EBUSY);
 238
 239         /*
 240          *      Mach version of ptrace executes request directly here,
 241          *      thus simplifying the interaction of ptrace and signals.
 242          */
 243         switch (uap->req) {
 244
 245         case PT_DETACH:
 246                 if (t->p_oppid != t->p_pptr->p_pid) {
 247                         struct proc *pp;
 248
 249                         pp = pfind(t->p_oppid);
 250                         proc_reparent(t, pp ? pp : initproc);
 251                 }
 252
 253                 t->p_oppid = 0;
 254                 CLR(t->p_flag, P_TRACED);
 255                 CLR(t->p_flag, P_SIGEXC);
 256                 goto resume;
 257
 258         case PT_KILL:
 259                 /*
 260                  *      Tell child process to kill itself after it
 261                  *      is resumed by adding NSIG to p_cursig. [see issig]
 262                  */
 263                 psignal_lock(t, SIGKILL, 0);
 264                 goto resume;
 265
 266         case PT_STEP:                   /* single step the child */
 267         case PT_CONTINUE:               /* continue the child */
 268                 th_act = (thread_t)get_firstthread(task);
 269                 if (th_act == THREAD_NULL)
 270                         goto errorLabel;
 271                 ut = (uthread_t)get_bsdthread_info(th_act);
 272                 locr0 = ut->uu_ar0;
 273 #if defined(i386)
 274                 state_count = i386_NEW_THREAD_STATE_COUNT;
 275                 if (thread_getstatus(th_act, i386_NEW_THREAD_STATE, &statep, &state_count)  != KERN_SUCCESS) {
 276                         goto errorLabel;
 277                 }
 278 #elif defined(ppc)
 279                 state_count = PPC_THREAD_STATE64_COUNT;
 280                 if (thread_getstatus(th_act, PPC_THREAD_STATE64, (thread_state_t)&statep, (mach_msg_type_number_t *)&state_count)  != KERN_SUCCESS) {
 281                         goto errorLabel;
 282                 }
 283 #else
 284 #error architecture not supported
 285 #endif
 286                 if (uap->addr != (user_addr_t)1) {
 287 #if     defined(i386)
 288                         locr0[PC] = (int)uap->addr;
 289 #elif   defined(ppc)
 290 #define ALIGNED(addr,size)      (((unsigned)(addr)&((size)-1))==0)
 291                 if (!ALIGNED((int)uap->addr, sizeof(int)))
 292                         return (ERESTART);
 293
 294                 statep.srr0 = uap->addr;
 295                 state_count = PPC_THREAD_STATE64_COUNT;
 296                 if (thread_setstatus(th_act, PPC_THREAD_STATE64, (thread_state_t)&statep, state_count)  != KERN_SUCCESS) {
 297                         goto errorLabel;
 298                 }
 299 #undef  ALIGNED
 300 #else
 301 #error architecture not implemented!
 302 #endif
 303                 } /* uap->addr != (user_addr_t)1 */
 304
 305                 if ((unsigned)uap->data >= NSIG)
 306                         goto errorLabel;
 307
 308                 if (uap->data != 0) {
 309                         psignal_lock(t, uap->data, 0);
 310                 }
 311 #if defined(ppc)
 312                 state_count = PPC_THREAD_STATE64_COUNT;
 313                 if (thread_getstatus(th_act, PPC_THREAD_STATE64, (thread_state_t)&statep, (mach_msg_type_number_t *)&state_count)  != KERN_SUCCESS) {
 314                         goto errorLabel;
 315                 }
 316 #endif
 317
 318 #define MSR_SE_BIT      21
 319
 320                 if (uap->req == PT_STEP) {
 321 #if     defined(i386)
 322                         locr0[PS] |= PSL_T;
 323 #elif   defined(ppc)
 324                         statep.srr1 |= MASK(MSR_SE);
 325 #else
 326 #error architecture not implemented!
 327 #endif
 328                 } /* uap->req == PT_STEP */
 329                 else {  /* PT_CONTINUE - clear trace bit if set */
 330 #if defined(i386)
 331                         locr0[PS] &= ~PSL_T;
 332 #elif defined(ppc)
 333                         statep.srr1 &= ~MASK(MSR_SE);
 334 #endif
 335                 }
 336 #if defined (ppc)
 337                 state_count = PPC_THREAD_STATE64_COUNT;
 338                 if (thread_setstatus(th_act, PPC_THREAD_STATE64, (thread_state_t)&statep, state_count)  != KERN_SUCCESS) {
 339                         goto errorLabel;
 340                 }
 341 #endif
 342         resume:
 343                 t->p_xstat = uap->data;
 344                 t->p_stat = SRUN;
 345                 if (t->sigwait) {
 346                         wakeup((caddr_t)&(t->sigwait));
 347                         if ((t->p_flag & P_SIGEXC) == 0)
 348                                 task_release(task);
 349                 }
 350                 break;
 351
 352         case PT_THUPDATE:  {
 353                 if ((unsigned)uap->data >= NSIG)
 354                         goto errorLabel;
 355                 th_act = port_name_to_thread(CAST_DOWN(mach_port_name_t, uap->addr));
 356                 if (th_act == THREAD_NULL)
 357                         return (ESRCH);
 358                 ut = (uthread_t)get_bsdthread_info(th_act);
 359                 if (uap->data)
 360                         ut->uu_siglist |= sigmask(uap->data);
 361                 t->p_xstat = uap->data;
 362                 t->p_stat = SRUN;
 363                 thread_deallocate(th_act);
 364                 return(0);
 365                 }
 366                 break;
 367 errorLabel:
 368         default:
 369                 return(EINVAL);
 370         }
 371
 372         return(0);
 373 }
 374
 375
 376 /*
 377  * determine if one process (cur_procp) can trace another process (traced_procp).
 378  */
 379
 380 int
 381 cantrace(proc_t cur_procp, kauth_cred_t creds, proc_t traced_procp, int *errp)
 382 {
 383         int             my_err;
 384         /*
 385          * You can't trace a process if:
 386          *      (1) it's the process that's doing the tracing,
 387          */
 388         if (traced_procp->p_pid == cur_procp->p_pid) {
 389                 *errp = EINVAL;
 390                 return (0);
 391         }
 392
 393         /*
 394          *      (2) it's already being traced, or
 395          */
 396         if (ISSET(traced_procp->p_flag, P_TRACED)) {
 397                 *errp = EBUSY;
 398                 return (0);
 399         }
 400
 401         /*
 402          *      (3) it's not owned by you, or is set-id on exec
 403          *          (unless you're root).
 404          */
 405         if ((creds->cr_ruid != proc_ucred(traced_procp)->cr_ruid ||
 406                 ISSET(traced_procp->p_flag, P_SUGID)) &&
 407                 (my_err = suser(creds, &cur_procp->p_acflag)) != 0) {
 408                 *errp = my_err;
 409                 return (0);
 410         }
 411
 412         if ((cur_procp->p_flag & P_TRACED) && isinferior(cur_procp, traced_procp)) {
 413                 *errp = EPERM;
 414                 return (0);
 415         }
 416
 417         if (ISSET(traced_procp->p_flag, P_NOATTACH)) {
 418                 *errp = EBUSY;
 419                 return (0);
 420         }
 421         return(1);
 422 }