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
  91
  92 /* Macros to clear/set/test flags. */
  93 #define SET(t, f)       (t) |= (f)
  94 #define CLR(t, f)       (t) &= ~(f)
  95 #define ISSET(t, f)     ((t) & (f))
  96
  97 extern thread_t port_name_to_thread(mach_port_name_t port_name);
  98 extern thread_t get_firstthread(task_t);
  99
 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 tr_sigexc = 0;
 116
 117         AUDIT_ARG(cmd, uap->req);
 118         AUDIT_ARG(pid, uap->pid);
 119         AUDIT_ARG(addr, uap->addr);
 120         AUDIT_ARG(value, uap->data);
 121
 122         if (uap->req == PT_DENY_ATTACH) {
 123                 if (ISSET(p->p_flag, P_TRACED)) {
 124                         exit1(p, W_EXITCODE(ENOTSUP, 0), retval);
 125                         /* drop funnel before we return */
 126                         thread_funnel_set(kernel_flock, FALSE);
 127                         thread_exception_return();
 128                         /* NOTREACHED */
 129                 }
 130                 SET(p->p_flag, P_NOATTACH);
 131
 132                 return(0);
 133         }
 134
 135         if (uap->req == PT_FORCEQUOTA) {
 136                 if (is_suser()) {
 137                         SET(t->p_flag, P_FORCEQUOTA);
 138                         return (0);
 139                 } else
 140                         return (EPERM);
 141         }
 142
 143         /*
 144          *      Intercept and deal with "please trace me" request.
 145          */
 146         if (uap->req == PT_TRACE_ME) {
 147                 SET(p->p_flag, P_TRACED);
 148                 /* Non-attached case, our tracer is our parent. */
 149                 t->p_oppid = t->p_pptr->p_pid;
 150                 return(0);
 151         }
 152         if (uap->req == PT_SIGEXC) {
 153                 if (ISSET(p->p_flag, P_TRACED)) {
 154                         SET(p->p_flag, P_SIGEXC);
 155                         return(0);
 156                 } else
 157                         return(EINVAL);
 158         }
 159
 160         /*
 161          *      Locate victim, and make sure it is traceable.
 162          */
 163         if ((t = pfind(uap->pid)) == NULL)
 164                         return (ESRCH);
 165
 166         AUDIT_ARG(process, t);
 167
 168         /* We do not want ptrace to do anything with kernel, init
 169          * and mach_init
 170          */
 171         if (uap->pid <=2 )
 172                 return (EPERM);
 173
 174         task = t->task;
 175         if (uap->req == PT_ATTACHEXC) {
 176                 uap->req = PT_ATTACH;
 177                 tr_sigexc = 1;
 178         }
 179         if (uap->req == PT_ATTACH) {
 180                 int             err;
 181
 182                 if ( kauth_authorize_process(proc_ucred(p), KAUTH_PROCESS_CANTRACE,
 183                                                                          t, (uintptr_t)&err, 0, 0) == 0 ) {
 184                         /* it's OK to attach */
 185                         SET(t->p_flag, P_TRACED);
 186                         if (tr_sigexc)
 187                                 SET(t->p_flag, P_SIGEXC);
 188
 189                         t->p_oppid = t->p_pptr->p_pid;
 190                         if (t->p_pptr != p)
 191                                 proc_reparent(t, p);
 192
 193                         if (get_task_userstop(task) == 0 ) {
 194                                 t->p_xstat = 0;
 195                                 psignal(t, SIGSTOP);
 196                         } else {
 197                                 t->p_xstat = SIGSTOP;
 198                                 task_resume(task);
 199                         }
 200                         return(0);
 201                 }
 202                 else {
 203                         /* not allowed to attach, proper error code returned by kauth_authorize_process */
 204                         if (ISSET(t->p_flag, P_NOATTACH)) {
 205                                 psignal(p, SIGSEGV);
 206                         }
 207                         return (err);
 208                 }
 209         }
 210
 211         /*
 212          * You can't do what you want to the process if:
 213          *      (1) It's not being traced at all,
 214          */
 215         if (!ISSET(t->p_flag, P_TRACED))
 216                 return (EPERM);
 217
 218         /*
 219          *      (2) it's not being traced by _you_, or
 220          */
 221         if (t->p_pptr != p)
 222                 return (EBUSY);
 223
 224         /*
 225          *      (3) it's not currently stopped.
 226          */
 227         if (t->p_stat != SSTOP)
 228                 return (EBUSY);
 229
 230         /*
 231          *      Mach version of ptrace executes request directly here,
 232          *      thus simplifying the interaction of ptrace and signals.
 233          */
 234         switch (uap->req) {
 235
 236         case PT_DETACH:
 237                 if (t->p_oppid != t->p_pptr->p_pid) {
 238                         struct proc *pp;
 239
 240                         pp = pfind(t->p_oppid);
 241                         proc_reparent(t, pp ? pp : initproc);
 242                 }
 243
 244                 t->p_oppid = 0;
 245                 CLR(t->p_flag, P_TRACED);
 246                 CLR(t->p_flag, P_SIGEXC);
 247                 goto resume;
 248
 249         case PT_KILL:
 250                 /*
 251                  *      Tell child process to kill itself after it
 252                  *      is resumed by adding NSIG to p_cursig. [see issig]
 253                  */
 254                 psignal_lock(t, SIGKILL, 0);
 255                 goto resume;
 256
 257         case PT_STEP:                   /* single step the child */
 258         case PT_CONTINUE:               /* continue the child */
 259                 th_act = (thread_t)get_firstthread(task);
 260                 if (th_act == THREAD_NULL)
 261                         goto errorLabel;
 262
 263                 if (uap->addr != (user_addr_t)1) {
 264 #if defined(ppc)
 265 #define ALIGNED(addr,size)      (((unsigned)(addr)&((size)-1))==0)
 266                         if (!ALIGNED((int)uap->addr, sizeof(int)))
 267                                 return (ERESTART);
 268 #undef  ALIGNED
 269 #endif
 270                         thread_setentrypoint(th_act, uap->addr);
 271                 }
 272
 273                 if ((unsigned)uap->data >= NSIG)
 274                         goto errorLabel;
 275
 276                 if (uap->data != 0) {
 277                         psignal_lock(t, uap->data, 0);
 278                 }
 279
 280                 if (uap->req == PT_STEP) {
 281                         /*
 282                          * set trace bit
 283                          */
 284                         thread_setsinglestep(th_act, 1);
 285                 } else {
 286                         /*
 287                          * clear trace bit if on
 288                          */
 289                         thread_setsinglestep(th_act, 0);
 290                 }
 291         resume:
 292                 t->p_xstat = uap->data;
 293                 t->p_stat = SRUN;
 294                 if (t->sigwait) {
 295                         wakeup((caddr_t)&(t->sigwait));
 296                         if ((t->p_flag & P_SIGEXC) == 0)
 297                                 task_release(task);
 298                 }
 299                 break;
 300
 301         case PT_THUPDATE:  {
 302                 if ((unsigned)uap->data >= NSIG)
 303                         goto errorLabel;
 304                 th_act = port_name_to_thread(CAST_DOWN(mach_port_name_t, uap->addr));
 305                 if (th_act == THREAD_NULL)
 306                         return (ESRCH);
 307                 ut = (uthread_t)get_bsdthread_info(th_act);
 308                 if (uap->data)
 309                         ut->uu_siglist |= sigmask(uap->data);
 310                 t->p_xstat = uap->data;
 311                 t->p_stat = SRUN;
 312                 thread_deallocate(th_act);
 313                 return(0);
 314                 }
 315                 break;
 316 errorLabel:
 317         default:
 318                 return(EINVAL);
 319         }
 320
 321         return(0);
 322 }
 323
 324
 325 /*
 326  * determine if one process (cur_procp) can trace another process (traced_procp).
 327  */
 328
 329 int
 330 cantrace(proc_t cur_procp, kauth_cred_t creds, proc_t traced_procp, int *errp)
 331 {
 332         int             my_err;
 333         /*
 334          * You can't trace a process if:
 335          *      (1) it's the process that's doing the tracing,
 336          */
 337         if (traced_procp->p_pid == cur_procp->p_pid) {
 338                 *errp = EINVAL;
 339                 return (0);
 340         }
 341
 342         /*
 343          *      (2) it's already being traced, or
 344          */
 345         if (ISSET(traced_procp->p_flag, P_TRACED)) {
 346                 *errp = EBUSY;
 347                 return (0);
 348         }
 349
 350         /*
 351          *      (3) it's not owned by you, or is set-id on exec
 352          *          (unless you're root).
 353          */
 354         if ((creds->cr_ruid != proc_ucred(traced_procp)->cr_ruid ||
 355                 ISSET(traced_procp->p_flag, P_SUGID)) &&
 356                 (my_err = suser(creds, &cur_procp->p_acflag)) != 0) {
 357                 *errp = my_err;
 358                 return (0);
 359         }
 360
 361         if ((cur_procp->p_flag & P_TRACED) && isinferior(cur_procp, traced_procp)) {
 362                 *errp = EPERM;
 363                 return (0);
 364         }
 365
 366         if (ISSET(traced_procp->p_flag, P_NOATTACH)) {
 367                 *errp = EBUSY;
 368                 return (0);
 369         }
 370         return(1);
 371 }