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
  85
  86 /* Macros to clear/set/test flags. */
  87 #define SET(t, f)       (t) |= (f)
  88 #define CLR(t, f)       (t) &= ~(f)
  89 #define ISSET(t, f)     ((t) & (f))
  90
  91 extern thread_t port_name_to_thread(mach_port_name_t port_name);
  92 extern thread_t get_firstthread(task_t);
  93
  94
  95 /*
  96  * sys-trace system call.
  97  */
  98
  99 int
 100 ptrace(p, uap, retval)
 101         struct proc *p;
 102         struct ptrace_args *uap;
 103         register_t *retval;
 104 {
 105         struct proc *t = current_proc();        /* target process */
 106         task_t          task;
 107         thread_t        th_act;
 108         struct uthread  *ut;
 109         int tr_sigexc = 0;
 110
 111         AUDIT_ARG(cmd, uap->req);
 112         AUDIT_ARG(pid, uap->pid);
 113         AUDIT_ARG(addr, uap->addr);
 114         AUDIT_ARG(value, uap->data);
 115
 116         if (uap->req == PT_DENY_ATTACH) {
 117                 if (ISSET(p->p_flag, P_TRACED)) {
 118                         exit1(p, W_EXITCODE(ENOTSUP, 0), retval);
 119                         /* drop funnel before we return */
 120                         thread_funnel_set(kernel_flock, FALSE);
 121                         thread_exception_return();
 122                         /* NOTREACHED */
 123                 }
 124                 SET(p->p_flag, P_NOATTACH);
 125
 126                 return(0);
 127         }
 128
 129         if (uap->req == PT_FORCEQUOTA) {
 130                 if (is_suser()) {
 131                         SET(t->p_flag, P_FORCEQUOTA);
 132                         return (0);
 133                 } else
 134                         return (EPERM);
 135         }
 136
 137         /*
 138          *      Intercept and deal with "please trace me" request.
 139          */
 140         if (uap->req == PT_TRACE_ME) {
 141                 SET(p->p_flag, P_TRACED);
 142                 /* Non-attached case, our tracer is our parent. */
 143                 t->p_oppid = t->p_pptr->p_pid;
 144                 return(0);
 145         }
 146         if (uap->req == PT_SIGEXC) {
 147                 if (ISSET(p->p_flag, P_TRACED)) {
 148                         SET(p->p_flag, P_SIGEXC);
 149                         return(0);
 150                 } else
 151                         return(EINVAL);
 152         }
 153
 154         /*
 155          *      Locate victim, and make sure it is traceable.
 156          */
 157         if ((t = pfind(uap->pid)) == NULL)
 158                         return (ESRCH);
 159
 160         AUDIT_ARG(process, t);
 161
 162         /* We do not want ptrace to do anything with kernel, init
 163          * and mach_init
 164          */
 165         if (uap->pid <=2 )
 166                 return (EPERM);
 167
 168         task = t->task;
 169         if (uap->req == PT_ATTACHEXC) {
 170                 uap->req = PT_ATTACH;
 171                 tr_sigexc = 1;
 172         }
 173         if (uap->req == PT_ATTACH) {
 174                 int             err;
 175
 176                 if ( kauth_authorize_process(proc_ucred(p), KAUTH_PROCESS_CANTRACE,
 177                                                                          t, (uintptr_t)&err, 0, 0) == 0 ) {
 178                         /* it's OK to attach */
 179                         SET(t->p_flag, P_TRACED);
 180                         if (tr_sigexc)
 181                                 SET(t->p_flag, P_SIGEXC);
 182
 183                         t->p_oppid = t->p_pptr->p_pid;
 184                         if (t->p_pptr != p)
 185                                 proc_reparent(t, p);
 186
 187                         if (get_task_userstop(task) == 0 ) {
 188                                 t->p_xstat = 0;
 189                                 psignal(t, SIGSTOP);
 190                         } else {
 191                                 t->p_xstat = SIGSTOP;
 192                                 task_resume(task);
 193                         }
 194                         return(0);
 195                 }
 196                 else {
 197                         /* not allowed to attach, proper error code returned by kauth_authorize_process */
 198                         if (ISSET(t->p_flag, P_NOATTACH)) {
 199                                 psignal(p, SIGSEGV);
 200                         }
 201                         return (err);
 202                 }
 203         }
 204
 205         /*
 206          * You can't do what you want to the process if:
 207          *      (1) It's not being traced at all,
 208          */
 209         if (!ISSET(t->p_flag, P_TRACED))
 210                 return (EPERM);
 211
 212         /*
 213          *      (2) it's not being traced by _you_, or
 214          */
 215         if (t->p_pptr != p)
 216                 return (EBUSY);
 217
 218         /*
 219          *      (3) it's not currently stopped.
 220          */
 221         if (t->p_stat != SSTOP)
 222                 return (EBUSY);
 223
 224         /*
 225          *      Mach version of ptrace executes request directly here,
 226          *      thus simplifying the interaction of ptrace and signals.
 227          */
 228         switch (uap->req) {
 229
 230         case PT_DETACH:
 231                 if (t->p_oppid != t->p_pptr->p_pid) {
 232                         struct proc *pp;
 233
 234                         pp = pfind(t->p_oppid);
 235                         proc_reparent(t, pp ? pp : initproc);
 236                 }
 237
 238                 t->p_oppid = 0;
 239                 CLR(t->p_flag, P_TRACED);
 240                 CLR(t->p_flag, P_SIGEXC);
 241                 goto resume;
 242
 243         case PT_KILL:
 244                 /*
 245                  *      Tell child process to kill itself after it
 246                  *      is resumed by adding NSIG to p_cursig. [see issig]
 247                  */
 248                 psignal_lock(t, SIGKILL, 0);
 249                 goto resume;
 250
 251         case PT_STEP:                   /* single step the child */
 252         case PT_CONTINUE:               /* continue the child */
 253                 th_act = (thread_t)get_firstthread(task);
 254                 if (th_act == THREAD_NULL)
 255                         goto errorLabel;
 256
 257                 if (uap->addr != (user_addr_t)1) {
 258 #if defined(ppc)
 259 #define ALIGNED(addr,size)      (((unsigned)(addr)&((size)-1))==0)
 260                         if (!ALIGNED((int)uap->addr, sizeof(int)))
 261                                 return (ERESTART);
 262 #undef  ALIGNED
 263 #endif
 264                         thread_setentrypoint(th_act, uap->addr);
 265                 }
 266
 267                 if ((unsigned)uap->data >= NSIG)
 268                         goto errorLabel;
 269
 270                 if (uap->data != 0) {
 271                         psignal_lock(t, uap->data, 0);
 272                 }
 273
 274                 if (uap->req == PT_STEP) {
 275                         /*
 276                          * set trace bit
 277                          */
 278                         thread_setsinglestep(th_act, 1);
 279                 } else {
 280                         /*
 281                          * clear trace bit if on
 282                          */
 283                         thread_setsinglestep(th_act, 0);
 284                 }
 285         resume:
 286                 t->p_xstat = uap->data;
 287                 t->p_stat = SRUN;
 288                 if (t->sigwait) {
 289                         wakeup((caddr_t)&(t->sigwait));
 290                         if ((t->p_flag & P_SIGEXC) == 0)
 291                                 task_release(task);
 292                 }
 293                 break;
 294
 295         case PT_THUPDATE:  {
 296                 if ((unsigned)uap->data >= NSIG)
 297                         goto errorLabel;
 298                 th_act = port_name_to_thread(CAST_DOWN(mach_port_name_t, uap->addr));
 299                 if (th_act == THREAD_NULL)
 300                         return (ESRCH);
 301                 ut = (uthread_t)get_bsdthread_info(th_act);
 302                 if (uap->data)
 303                         ut->uu_siglist |= sigmask(uap->data);
 304                 t->p_xstat = uap->data;
 305                 t->p_stat = SRUN;
 306                 thread_deallocate(th_act);
 307                 return(0);
 308                 }
 309                 break;
 310 errorLabel:
 311         default:
 312                 return(EINVAL);
 313         }
 314
 315         return(0);
 316 }
 317
 318
 319 /*
 320  * determine if one process (cur_procp) can trace another process (traced_procp).
 321  */
 322
 323 int
 324 cantrace(proc_t cur_procp, kauth_cred_t creds, proc_t traced_procp, int *errp)
 325 {
 326         int             my_err;
 327         /*
 328          * You can't trace a process if:
 329          *      (1) it's the process that's doing the tracing,
 330          */
 331         if (traced_procp->p_pid == cur_procp->p_pid) {
 332                 *errp = EINVAL;
 333                 return (0);
 334         }
 335
 336         /*
 337          *      (2) it's already being traced, or
 338          */
 339         if (ISSET(traced_procp->p_flag, P_TRACED)) {
 340                 *errp = EBUSY;
 341                 return (0);
 342         }
 343
 344         /*
 345          *      (3) it's not owned by you, or is set-id on exec
 346          *          (unless you're root).
 347          */
 348         if ((creds->cr_ruid != proc_ucred(traced_procp)->cr_ruid ||
 349                 ISSET(traced_procp->p_flag, P_SUGID)) &&
 350                 (my_err = suser(creds, &cur_procp->p_acflag)) != 0) {
 351                 *errp = my_err;
 352                 return (0);
 353         }
 354
 355         if ((cur_procp->p_flag & P_TRACED) && isinferior(cur_procp, traced_procp)) {
 356                 *errp = EPERM;
 357                 return (0);
 358         }
 359
 360         if (ISSET(traced_procp->p_flag, P_NOATTACH)) {
 361                 *errp = EBUSY;
 362                 return (0);
 363         }
 364         return(1);
 365 }