bsd/kern/mach_process.c

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