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  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */
  23 /*-
  24  * Copyright (c) 1982, 1986, 1989, 1993
  25  *      The Regents of the University of California.  All rights reserved.
  26  * (c) UNIX System Laboratories, Inc.
  27  * All or some portions of this file are derived from material licensed
  28  * to the University of California by American Telephone and Telegraph
  29  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
  30  * the permission of UNIX System Laboratories, Inc.
  31  *
  32  * Redistribution and use in source and binary forms, with or without
  33  * modification, are permitted provided that the following conditions
  34  * are met:
  35  * 1. Redistributions of source code must retain the above copyright
  36  *    notice, this list of conditions and the following disclaimer.
  37  * 2. Redistributions in binary form must reproduce the above copyright
  38  *    notice, this list of conditions and the following disclaimer in the
  39  *    documentation and/or other materials provided with the distribution.
  40  * 3. All advertising materials mentioning features or use of this software
  41  *    must display the following acknowledgement:
  42  *      This product includes software developed by the University of
  43  *      California, Berkeley and its contributors.
  44  * 4. Neither the name of the University nor the names of its contributors
  45  *    may be used to endorse or promote products derived from this software
  46  *    without specific prior written permission.
  47  *
  48  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  49  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  50  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  51  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  52  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  53  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  54  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  55  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  56  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  57  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  58  * SUCH DAMAGE.
  59  *
  60  *      from: @(#)sys_process.c 8.1 (Berkeley) 6/10/93
  61  */
  62
  63 #include <machine/reg.h>
  64 #include <machine/psl.h>
  65
  66 #include <sys/param.h>
  67 #include <sys/systm.h>
  68 #include <sys/proc_internal.h>
  69 #include <sys/kauth.h>
  70 #include <sys/errno.h>
  71 #include <sys/ptrace.h>
  72 #include <sys/uio.h>
  73 #include <sys/user.h>
  74 #include <sys/sysctl.h>
  75 #include <sys/wait.h>
  76
  77 #include <sys/mount_internal.h>
  78 #include <sys/sysproto.h>
  79
  80 #include <bsm/audit_kernel.h>
  81
  82 #include <kern/task.h>
  83 #include <kern/thread.h>
  84 #include <mach/machine/thread_status.h>
  85
  86
  87 /* Macros to clear/set/test flags. */
  88 #define SET(t, f)       (t) |= (f)
  89 #define CLR(t, f)       (t) &= ~(f)
  90 #define ISSET(t, f)     ((t) & (f))
  91
  92 extern thread_t port_name_to_thread(mach_port_name_t port_name);
  93 extern kern_return_t thread_getstatus(thread_t thread, int flavor, thread_state_t tstate, mach_msg_type_number_t *count);
  94 extern thread_t get_firstthread(task_t);
  95
  96 #if defined (ppc)
  97 extern kern_return_t thread_setstatus(thread_t thread, int flavor, thread_state_t tstate, mach_msg_type_number_t count);
  98 #endif
  99
 100 /*
 101  * sys-trace system call.
 102  */
 103
 104 int
 105 ptrace(p, uap, retval)
 106         struct proc *p;
 107         struct ptrace_args *uap;
 108         register_t *retval;
 109 {
 110         struct proc *t = current_proc();        /* target process */
 111         task_t          task;
 112         thread_t        th_act;
 113         struct uthread  *ut;
 114         int             *locr0;
 115 #if defined(ppc)
 116         struct ppc_thread_state64 statep;
 117 #elif   defined(i386)
 118         struct i386_saved_state statep;
 119 #else
 120 #error architecture not supported
 121 #endif
 122         unsigned long state_count;
 123         int tr_sigexc = 0;
 124
 125         AUDIT_ARG(cmd, uap->req);
 126         AUDIT_ARG(pid, uap->pid);
 127         AUDIT_ARG(addr, uap->addr);
 128         AUDIT_ARG(value, uap->data);
 129
 130         if (uap->req == PT_DENY_ATTACH) {
 131                 if (ISSET(p->p_flag, P_TRACED)) {
 132                         exit1(p, W_EXITCODE(ENOTSUP, 0), retval);
 133                         /* drop funnel before we return */
 134                         thread_funnel_set(kernel_flock, FALSE);
 135                         thread_exception_return();
 136                         /* NOTREACHED */
 137                 }
 138                 SET(p->p_flag, P_NOATTACH);
 139
 140                 return(0);
 141         }
 142
 143         if (uap->req == PT_FORCEQUOTA) {
 144                 if (is_suser()) {
 145                         SET(t->p_flag, P_FORCEQUOTA);
 146                         return (0);
 147                 } else
 148                         return (EPERM);
 149         }
 150
 151         /*
 152          *      Intercept and deal with "please trace me" request.
 153          */
 154         if (uap->req == PT_TRACE_ME) {
 155                 SET(p->p_flag, P_TRACED);
 156                 /* Non-attached case, our tracer is our parent. */
 157                 t->p_oppid = t->p_pptr->p_pid;
 158                 return(0);
 159         }
 160         if (uap->req == PT_SIGEXC) {
 161                 if (ISSET(p->p_flag, P_TRACED)) {
 162                         SET(p->p_flag, P_SIGEXC);
 163                         return(0);
 164                 } else
 165                         return(EINVAL);
 166         }
 167
 168         /*
 169          *      Locate victim, and make sure it is traceable.
 170          */
 171         if ((t = pfind(uap->pid)) == NULL)
 172                         return (ESRCH);
 173
 174         AUDIT_ARG(process, t);
 175
 176         /* We do not want ptrace to do anything with kernel, init
 177          * and mach_init
 178          */
 179         if (uap->pid <=2 )
 180                 return (EPERM);
 181
 182         task = t->task;
 183         if (uap->req == PT_ATTACHEXC) {
 184                 uap->req = PT_ATTACH;
 185                 tr_sigexc = 1;
 186         }
 187         if (uap->req == PT_ATTACH) {
 188                 int             err;
 189
 190                 if ( kauth_authorize_process(proc_ucred(p), KAUTH_PROCESS_CANTRACE,
 191                                                                          t, (uintptr_t)&err, 0, 0) == 0 ) {
 192                         /* it's OK to attach */
 193                         SET(t->p_flag, P_TRACED);
 194                         if (tr_sigexc)
 195                                 SET(t->p_flag, P_SIGEXC);
 196
 197                         t->p_oppid = t->p_pptr->p_pid;
 198                         if (t->p_pptr != p)
 199                                 proc_reparent(t, p);
 200
 201                         if (get_task_userstop(task) == 0 ) {
 202                                 t->p_xstat = 0;
 203                                 psignal(t, SIGSTOP);
 204                         } else {
 205                                 t->p_xstat = SIGSTOP;
 206                                 task_resume(task);
 207                         }
 208                         return(0);
 209                 }
 210                 else {
 211                         /* not allowed to attach, proper error code returned by kauth_authorize_process */
 212                         if (ISSET(t->p_flag, P_NOATTACH)) {
 213                                 psignal(p, SIGSEGV);
 214                         }
 215                         return (err);
 216                 }
 217         }
 218
 219         /*
 220          * You can't do what you want to the process if:
 221          *      (1) It's not being traced at all,
 222          */
 223         if (!ISSET(t->p_flag, P_TRACED))
 224                 return (EPERM);
 225
 226         /*
 227          *      (2) it's not being traced by _you_, or
 228          */
 229         if (t->p_pptr != p)
 230                 return (EBUSY);
 231
 232         /*
 233          *      (3) it's not currently stopped.
 234          */
 235         if (t->p_stat != SSTOP)
 236                 return (EBUSY);
 237
 238         /*
 239          *      Mach version of ptrace executes request directly here,
 240          *      thus simplifying the interaction of ptrace and signals.
 241          */
 242         switch (uap->req) {
 243
 244         case PT_DETACH:
 245                 if (t->p_oppid != t->p_pptr->p_pid) {
 246                         struct proc *pp;
 247
 248                         pp = pfind(t->p_oppid);
 249                         proc_reparent(t, pp ? pp : initproc);
 250                 }
 251
 252                 t->p_oppid = 0;
 253                 CLR(t->p_flag, P_TRACED);
 254                 CLR(t->p_flag, P_SIGEXC);
 255                 goto resume;
 256
 257         case PT_KILL:
 258                 /*
 259                  *      Tell child process to kill itself after it
 260                  *      is resumed by adding NSIG to p_cursig. [see issig]
 261                  */
 262                 psignal_lock(t, SIGKILL, 0);
 263                 goto resume;
 264
 265         case PT_STEP:                   /* single step the child */
 266         case PT_CONTINUE:               /* continue the child */
 267                 th_act = (thread_t)get_firstthread(task);
 268                 if (th_act == THREAD_NULL)
 269                         goto errorLabel;
 270                 ut = (uthread_t)get_bsdthread_info(th_act);
 271                 locr0 = ut->uu_ar0;
 272 #if defined(i386)
 273                 state_count = i386_NEW_THREAD_STATE_COUNT;
 274                 if (thread_getstatus(th_act, i386_NEW_THREAD_STATE, &statep, &state_count)  != KERN_SUCCESS) {
 275                         goto errorLabel;
 276                 }
 277 #elif defined(ppc)
 278                 state_count = PPC_THREAD_STATE64_COUNT;
 279                 if (thread_getstatus(th_act, PPC_THREAD_STATE64, (thread_state_t)&statep, (mach_msg_type_number_t *)&state_count)  != KERN_SUCCESS) {
 280                         goto errorLabel;
 281                 }
 282 #else
 283 #error architecture not supported
 284 #endif
 285                 if (uap->addr != (user_addr_t)1) {
 286 #if     defined(i386)
 287                         locr0[PC] = (int)uap->addr;
 288 #elif   defined(ppc)
 289 #define ALIGNED(addr,size)      (((unsigned)(addr)&((size)-1))==0)
 290                 if (!ALIGNED((int)uap->addr, sizeof(int)))
 291                         return (ERESTART);
 292
 293                 statep.srr0 = uap->addr;
 294                 state_count = PPC_THREAD_STATE64_COUNT;
 295                 if (thread_setstatus(th_act, PPC_THREAD_STATE64, (thread_state_t)&statep, state_count)  != KERN_SUCCESS) {
 296                         goto errorLabel;
 297                 }
 298 #undef  ALIGNED
 299 #else
 300 #error architecture not implemented!
 301 #endif
 302                 } /* uap->addr != (user_addr_t)1 */
 303
 304                 if ((unsigned)uap->data >= NSIG)
 305                         goto errorLabel;
 306
 307                 if (uap->data != 0) {
 308                         psignal_lock(t, uap->data, 0);
 309                 }
 310 #if defined(ppc)
 311                 state_count = PPC_THREAD_STATE64_COUNT;
 312                 if (thread_getstatus(th_act, PPC_THREAD_STATE64, (thread_state_t)&statep, (mach_msg_type_number_t *)&state_count)  != KERN_SUCCESS) {
 313                         goto errorLabel;
 314                 }
 315 #endif
 316
 317 #define MSR_SE_BIT      21
 318
 319                 if (uap->req == PT_STEP) {
 320 #if     defined(i386)
 321                         locr0[PS] |= PSL_T;
 322 #elif   defined(ppc)
 323                         statep.srr1 |= MASK(MSR_SE);
 324 #else
 325 #error architecture not implemented!
 326 #endif
 327                 } /* uap->req == PT_STEP */
 328                 else {  /* PT_CONTINUE - clear trace bit if set */
 329 #if defined(i386)
 330                         locr0[PS] &= ~PSL_T;
 331 #elif defined(ppc)
 332                         statep.srr1 &= ~MASK(MSR_SE);
 333 #endif
 334                 }
 335 #if defined (ppc)
 336                 state_count = PPC_THREAD_STATE64_COUNT;
 337                 if (thread_setstatus(th_act, PPC_THREAD_STATE64, (thread_state_t)&statep, state_count)  != KERN_SUCCESS) {
 338                         goto errorLabel;
 339                 }
 340 #endif
 341         resume:
 342                 t->p_xstat = uap->data;
 343                 t->p_stat = SRUN;
 344                 if (t->sigwait) {
 345                         wakeup((caddr_t)&(t->sigwait));
 346                         if ((t->p_flag & P_SIGEXC) == 0)
 347                                 task_release(task);
 348                 }
 349                 break;
 350
 351         case PT_THUPDATE:  {
 352                 if ((unsigned)uap->data >= NSIG)
 353                         goto errorLabel;
 354                 th_act = port_name_to_thread(CAST_DOWN(mach_port_name_t, uap->addr));
 355                 if (th_act == THREAD_NULL)
 356                         return (ESRCH);
 357                 ut = (uthread_t)get_bsdthread_info(th_act);
 358                 if (uap->data)
 359                         ut->uu_siglist |= sigmask(uap->data);
 360                 t->p_xstat = uap->data;
 361                 t->p_stat = SRUN;
 362                 thread_deallocate(th_act);
 363                 return(0);
 364                 }
 365                 break;
 366 errorLabel:
 367         default:
 368                 return(EINVAL);
 369         }
 370
 371         return(0);
 372 }
 373
 374
 375 /*
 376  * determine if one process (cur_procp) can trace another process (traced_procp).
 377  */
 378
 379 int
 380 cantrace(proc_t cur_procp, kauth_cred_t creds, proc_t traced_procp, int *errp)
 381 {
 382         int             my_err;
 383         /*
 384          * You can't trace a process if:
 385          *      (1) it's the process that's doing the tracing,
 386          */
 387         if (traced_procp->p_pid == cur_procp->p_pid) {
 388                 *errp = EINVAL;
 389                 return (0);
 390         }
 391
 392         /*
 393          *      (2) it's already being traced, or
 394          */
 395         if (ISSET(traced_procp->p_flag, P_TRACED)) {
 396                 *errp = EBUSY;
 397                 return (0);
 398         }
 399
 400         /*
 401          *      (3) it's not owned by you, or is set-id on exec
 402          *          (unless you're root).
 403          */
 404         if ((creds->cr_ruid != proc_ucred(traced_procp)->cr_ruid ||
 405                 ISSET(traced_procp->p_flag, P_SUGID)) &&
 406                 (my_err = suser(creds, &cur_procp->p_acflag)) != 0) {
 407                 *errp = my_err;
 408                 return (0);
 409         }
 410
 411         if ((cur_procp->p_flag & P_TRACED) && isinferior(cur_procp, traced_procp)) {
 412                 *errp = EPERM;
 413                 return (0);
 414         }
 415
 416         if (ISSET(traced_procp->p_flag, P_NOATTACH)) {
 417                 *errp = EBUSY;
 418                 return (0);
 419         }
 420         return(1);
 421 }