xref: /netbsd-src/sys/kern/sys_process.c (revision aad9773e38ed2370a628a6416e098f9008fc10a7)
1 /*	$NetBSD: sys_process.c,v 1.165 2014/11/24 02:34:04 christos Exp $	*/
2 
3 /*-
4  * Copyright (c) 2008, 2009 The NetBSD Foundation, Inc.
5  * All rights reserved.
6  *
7  * This code is derived from software contributed to The NetBSD Foundation
8  * by Andrew Doran.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29  * POSSIBILITY OF SUCH DAMAGE.
30  */
31 
32 /*-
33  * Copyright (c) 1982, 1986, 1989, 1993
34  *	The Regents of the University of California.  All rights reserved.
35  * (c) UNIX System Laboratories, Inc.
36  * All or some portions of this file are derived from material licensed
37  * to the University of California by American Telephone and Telegraph
38  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
39  * the permission of UNIX System Laboratories, Inc.
40  *
41  * This code is derived from software contributed to Berkeley by
42  * Jan-Simon Pendry.
43  *
44  * Redistribution and use in source and binary forms, with or without
45  * modification, are permitted provided that the following conditions
46  * are met:
47  * 1. Redistributions of source code must retain the above copyright
48  *    notice, this list of conditions and the following disclaimer.
49  * 2. Redistributions in binary form must reproduce the above copyright
50  *    notice, this list of conditions and the following disclaimer in the
51  *    documentation and/or other materials provided with the distribution.
52  * 3. 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 /*-
72  * Copyright (c) 1993 Jan-Simon Pendry.
73  * Copyright (c) 1994 Christopher G. Demetriou.  All rights reserved.
74  *
75  * This code is derived from software contributed to Berkeley by
76  * Jan-Simon Pendry.
77  *
78  * Redistribution and use in source and binary forms, with or without
79  * modification, are permitted provided that the following conditions
80  * are met:
81  * 1. Redistributions of source code must retain the above copyright
82  *    notice, this list of conditions and the following disclaimer.
83  * 2. Redistributions in binary form must reproduce the above copyright
84  *    notice, this list of conditions and the following disclaimer in the
85  *    documentation and/or other materials provided with the distribution.
86  * 3. All advertising materials mentioning features or use of this software
87  *    must display the following acknowledgement:
88  *	This product includes software developed by the University of
89  *	California, Berkeley and its contributors.
90  * 4. Neither the name of the University nor the names of its contributors
91  *    may be used to endorse or promote products derived from this software
92  *    without specific prior written permission.
93  *
94  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
95  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
96  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
97  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
98  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
99  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
100  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
101  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
102  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
103  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
104  * SUCH DAMAGE.
105  *
106  *	from: @(#)sys_process.c	8.1 (Berkeley) 6/10/93
107  */
108 
109 /*
110  * References:
111  *	(1) Bach's "The Design of the UNIX Operating System",
112  *	(2) sys/miscfs/procfs from UCB's 4.4BSD-Lite distribution,
113  *	(3) the "4.4BSD Programmer's Reference Manual" published
114  *		by USENIX and O'Reilly & Associates.
115  * The 4.4BSD PRM does a reasonably good job of documenting what the various
116  * ptrace() requests should actually do, and its text is quoted several times
117  * in this file.
118  */
119 
120 #include <sys/cdefs.h>
121 __KERNEL_RCSID(0, "$NetBSD: sys_process.c,v 1.165 2014/11/24 02:34:04 christos Exp $");
122 
123 #include "opt_ptrace.h"
124 #include "opt_ktrace.h"
125 
126 #include <sys/param.h>
127 #include <sys/systm.h>
128 #include <sys/proc.h>
129 #include <sys/errno.h>
130 #include <sys/ptrace.h>
131 #include <sys/uio.h>
132 #include <sys/ras.h>
133 #include <sys/kmem.h>
134 #include <sys/kauth.h>
135 #include <sys/mount.h>
136 #include <sys/syscallargs.h>
137 
138 #include <uvm/uvm_extern.h>
139 
140 #include <machine/reg.h>
141 
142 #ifdef PTRACE
143 
144 # ifdef DEBUG
145 #  define DPRINTF(a) uprintf a
146 # else
147 #  define DPRINTF(a)
148 # endif
149 
150 static kauth_listener_t ptrace_listener;
151 
152 static int
153 ptrace_listener_cb(kauth_cred_t cred, kauth_action_t action, void *cookie,
154     void *arg0, void *arg1, void *arg2, void *arg3)
155 {
156 	struct proc *p;
157 	int result;
158 
159 	result = KAUTH_RESULT_DEFER;
160 	p = arg0;
161 
162 	if (action != KAUTH_PROCESS_PTRACE)
163 		return result;
164 
165 	switch ((u_long)arg1) {
166 	case PT_TRACE_ME:
167 	case PT_ATTACH:
168 	case PT_WRITE_I:
169 	case PT_WRITE_D:
170 	case PT_READ_I:
171 	case PT_READ_D:
172 	case PT_IO:
173 #ifdef PT_GETREGS
174 	case PT_GETREGS:
175 #endif
176 #ifdef PT_SETREGS
177 	case PT_SETREGS:
178 #endif
179 #ifdef PT_GETFPREGS
180 	case PT_GETFPREGS:
181 #endif
182 #ifdef PT_SETFPREGS
183 	case PT_SETFPREGS:
184 #endif
185 	case PT_SET_EVENT_MASK:
186 	case PT_GET_EVENT_MASK:
187 	case PT_GET_PROCESS_STATE:
188 #ifdef __HAVE_PTRACE_MACHDEP
189 	PTRACE_MACHDEP_REQUEST_CASES
190 #endif
191 		if (kauth_cred_getuid(cred) != kauth_cred_getuid(p->p_cred) ||
192 		    ISSET(p->p_flag, PK_SUGID)) {
193 			break;
194 		}
195 
196 		result = KAUTH_RESULT_ALLOW;
197 
198 	break;
199 
200 #ifdef PT_STEP
201 	case PT_STEP:
202 #endif
203 	case PT_CONTINUE:
204 	case PT_KILL:
205 	case PT_DETACH:
206 	case PT_LWPINFO:
207 	case PT_SYSCALL:
208 	case PT_SYSCALLEMU:
209 	case PT_DUMPCORE:
210 		result = KAUTH_RESULT_ALLOW;
211 		break;
212 
213 	default:
214 		break;
215 	}
216 
217 	return result;
218 }
219 
220 void
221 ptrace_init(void)
222 {
223 
224 	ptrace_listener = kauth_listen_scope(KAUTH_SCOPE_PROCESS,
225 	    ptrace_listener_cb, NULL);
226 }
227 
228 /*
229  * Process debugging system call.
230  */
231 int
232 sys_ptrace(struct lwp *l, const struct sys_ptrace_args *uap, register_t *retval)
233 {
234 	/* {
235 		syscallarg(int) req;
236 		syscallarg(pid_t) pid;
237 		syscallarg(void *) addr;
238 		syscallarg(int) data;
239 	} */
240 	struct proc *p = l->l_proc;
241 	struct lwp *lt;
242 #ifdef PT_STEP
243 	struct lwp *lt2;
244 #endif
245 	struct proc *t;				/* target process */
246 	struct uio uio;
247 	struct iovec iov;
248 	struct ptrace_io_desc piod;
249 	struct ptrace_event pe;
250 	struct ptrace_state ps;
251 	struct ptrace_lwpinfo pl;
252 	struct vmspace *vm;
253 	int error, write, tmp, req, pheld;
254 	int signo = 0;
255 	int resume_all;
256 	ksiginfo_t ksi;
257 	char *path;
258 	int len = 0;
259 
260 	error = 0;
261 	req = SCARG(uap, req);
262 
263 	/*
264 	 * If attaching or detaching, we need to get a write hold on the
265 	 * proclist lock so that we can re-parent the target process.
266 	 */
267 	mutex_enter(proc_lock);
268 
269 	/* "A foolish consistency..." XXX */
270 	if (req == PT_TRACE_ME) {
271 		t = p;
272 		mutex_enter(t->p_lock);
273 	} else {
274 		/* Find the process we're supposed to be operating on. */
275 		t = proc_find(SCARG(uap, pid));
276 		if (t == NULL) {
277 			mutex_exit(proc_lock);
278 			return (ESRCH);
279 		}
280 
281 		/* XXX-elad */
282 		mutex_enter(t->p_lock);
283 		error = kauth_authorize_process(l->l_cred, KAUTH_PROCESS_CANSEE,
284 		    t, KAUTH_ARG(KAUTH_REQ_PROCESS_CANSEE_ENTRY), NULL, NULL);
285 		if (error) {
286 			mutex_exit(proc_lock);
287 			mutex_exit(t->p_lock);
288 			return (ESRCH);
289 		}
290 	}
291 
292 	/*
293 	 * Grab a reference on the process to prevent it from execing or
294 	 * exiting.
295 	 */
296 	if (!rw_tryenter(&t->p_reflock, RW_READER)) {
297 		mutex_exit(proc_lock);
298 		mutex_exit(t->p_lock);
299 		return EBUSY;
300 	}
301 
302 	/* Make sure we can operate on it. */
303 	switch (req) {
304 	case  PT_TRACE_ME:
305 		/* Saying that you're being traced is always legal. */
306 		break;
307 
308 	case  PT_ATTACH:
309 		/*
310 		 * You can't attach to a process if:
311 		 *	(1) it's the process that's doing the attaching,
312 		 */
313 		if (t->p_pid == p->p_pid) {
314 			error = EINVAL;
315 			break;
316 		}
317 
318 		/*
319 		 *  (2) it's a system process
320 		 */
321 		if (t->p_flag & PK_SYSTEM) {
322 			error = EPERM;
323 			break;
324 		}
325 
326 		/*
327 		 *	(3) it's already being traced, or
328 		 */
329 		if (ISSET(t->p_slflag, PSL_TRACED)) {
330 			error = EBUSY;
331 			break;
332 		}
333 
334 		/*
335 		 * 	(4) the tracer is chrooted, and its root directory is
336 		 * 	    not at or above the root directory of the tracee
337 		 */
338 		mutex_exit(t->p_lock);	/* XXXSMP */
339 		tmp = proc_isunder(t, l);
340 		mutex_enter(t->p_lock);	/* XXXSMP */
341 		if (!tmp) {
342 			error = EPERM;
343 			break;
344 		}
345 		break;
346 
347 	case  PT_READ_I:
348 	case  PT_READ_D:
349 	case  PT_WRITE_I:
350 	case  PT_WRITE_D:
351 	case  PT_IO:
352 #ifdef PT_GETREGS
353 	case  PT_GETREGS:
354 #endif
355 #ifdef PT_SETREGS
356 	case  PT_SETREGS:
357 #endif
358 #ifdef PT_GETFPREGS
359 	case  PT_GETFPREGS:
360 #endif
361 #ifdef PT_SETFPREGS
362 	case  PT_SETFPREGS:
363 #endif
364 #ifdef __HAVE_PTRACE_MACHDEP
365 	PTRACE_MACHDEP_REQUEST_CASES
366 #endif
367 		/*
368 		 * You can't read/write the memory or registers of a process
369 		 * if the tracer is chrooted, and its root directory is not at
370 		 * or above the root directory of the tracee.
371 		 */
372 		mutex_exit(t->p_lock);	/* XXXSMP */
373 		tmp = proc_isunder(t, l);
374 		mutex_enter(t->p_lock);	/* XXXSMP */
375 		if (!tmp) {
376 			error = EPERM;
377 			break;
378 		}
379 		/*FALLTHROUGH*/
380 
381 	case  PT_CONTINUE:
382 	case  PT_KILL:
383 	case  PT_DETACH:
384 	case  PT_LWPINFO:
385 	case  PT_SYSCALL:
386 	case  PT_SYSCALLEMU:
387 	case  PT_DUMPCORE:
388 #ifdef PT_STEP
389 	case  PT_STEP:
390 #endif
391 	case  PT_SET_EVENT_MASK:
392 	case  PT_GET_EVENT_MASK:
393 	case  PT_GET_PROCESS_STATE:
394 		/*
395 		 * You can't do what you want to the process if:
396 		 *	(1) It's not being traced at all,
397 		 */
398 		if (!ISSET(t->p_slflag, PSL_TRACED)) {
399 			error = EPERM;
400 			break;
401 		}
402 
403 		/*
404 		 *	(2) it's being traced by procfs (which has
405 		 *	    different signal delivery semantics),
406 		 */
407 		if (ISSET(t->p_slflag, PSL_FSTRACE)) {
408 			DPRINTF(("file system traced\n"));
409 			error = EBUSY;
410 			break;
411 		}
412 
413 		/*
414 		 *	(3) it's not being traced by _you_, or
415 		 */
416 		if (t->p_pptr != p) {
417 			DPRINTF(("parent %d != %d\n", t->p_pptr->p_pid,
418 			    p->p_pid));
419 			error = EBUSY;
420 			break;
421 		}
422 
423 		/*
424 		 *	(4) it's not currently stopped.
425 		 */
426 		if (t->p_stat != SSTOP || !t->p_waited /* XXXSMP */) {
427 			DPRINTF(("stat %d flag %d\n", t->p_stat,
428 			    !t->p_waited));
429 			error = EBUSY;
430 			break;
431 		}
432 		break;
433 
434 	default:			/* It was not a legal request. */
435 		error = EINVAL;
436 		break;
437 	}
438 
439 	if (error == 0) {
440 		error = kauth_authorize_process(l->l_cred,
441 		    KAUTH_PROCESS_PTRACE, t, KAUTH_ARG(req),
442 		    NULL, NULL);
443 	}
444 	if (error == 0) {
445 		lt = lwp_find_first(t);
446 		if (lt == NULL)
447 			error = ESRCH;
448 	}
449 
450 	if (error != 0) {
451 		mutex_exit(proc_lock);
452 		mutex_exit(t->p_lock);
453 		rw_exit(&t->p_reflock);
454 		return error;
455 	}
456 
457 	/* Do single-step fixup if needed. */
458 	FIX_SSTEP(t);
459 	KASSERT(lt != NULL);
460 	lwp_addref(lt);
461 
462 	/*
463 	 * Which locks do we need held? XXX Ugly.
464 	 */
465 	switch (req) {
466 #ifdef PT_STEP
467 	case PT_STEP:
468 #endif
469 	case PT_CONTINUE:
470 	case PT_DETACH:
471 	case PT_KILL:
472 	case PT_SYSCALL:
473 	case PT_SYSCALLEMU:
474 	case PT_ATTACH:
475 	case PT_TRACE_ME:
476 		pheld = 1;
477 		break;
478 	default:
479 		mutex_exit(proc_lock);
480 		mutex_exit(t->p_lock);
481 		pheld = 0;
482 		break;
483 	}
484 
485 	/* Now do the operation. */
486 	write = 0;
487 	*retval = 0;
488 	tmp = 0;
489 	resume_all = 1;
490 
491 	switch (req) {
492 	case  PT_TRACE_ME:
493 		/* Just set the trace flag. */
494 		SET(t->p_slflag, PSL_TRACED);
495 		t->p_opptr = t->p_pptr;
496 		break;
497 
498 	case  PT_WRITE_I:		/* XXX no separate I and D spaces */
499 	case  PT_WRITE_D:
500 #if defined(__HAVE_RAS)
501 		/*
502 		 * Can't write to a RAS
503 		 */
504 		if (ras_lookup(t, SCARG(uap, addr)) != (void *)-1) {
505 			error = EACCES;
506 			break;
507 		}
508 #endif
509 		write = 1;
510 		tmp = SCARG(uap, data);
511 		/* FALLTHROUGH */
512 
513 	case  PT_READ_I:		/* XXX no separate I and D spaces */
514 	case  PT_READ_D:
515 		/* write = 0 done above. */
516 		iov.iov_base = (void *)&tmp;
517 		iov.iov_len = sizeof(tmp);
518 		uio.uio_iov = &iov;
519 		uio.uio_iovcnt = 1;
520 		uio.uio_offset = (off_t)(unsigned long)SCARG(uap, addr);
521 		uio.uio_resid = sizeof(tmp);
522 		uio.uio_rw = write ? UIO_WRITE : UIO_READ;
523 		UIO_SETUP_SYSSPACE(&uio);
524 
525 		error = process_domem(l, lt, &uio);
526 		if (!write)
527 			*retval = tmp;
528 		break;
529 
530 	case  PT_IO:
531 		error = copyin(SCARG(uap, addr), &piod, sizeof(piod));
532 		if (error)
533 			break;
534 		switch (piod.piod_op) {
535 		case PIOD_READ_D:
536 		case PIOD_READ_I:
537 			uio.uio_rw = UIO_READ;
538 			break;
539 		case PIOD_WRITE_D:
540 		case PIOD_WRITE_I:
541 			/*
542 			 * Can't write to a RAS
543 			 */
544 			if (ras_lookup(t, SCARG(uap, addr)) != (void *)-1) {
545 				return (EACCES);
546 			}
547 			uio.uio_rw = UIO_WRITE;
548 			break;
549 		default:
550 			error = EINVAL;
551 			break;
552 		}
553 		if (error)
554 			break;
555 		error = proc_vmspace_getref(l->l_proc, &vm);
556 		if (error)
557 			break;
558 		iov.iov_base = piod.piod_addr;
559 		iov.iov_len = piod.piod_len;
560 		uio.uio_iov = &iov;
561 		uio.uio_iovcnt = 1;
562 		uio.uio_offset = (off_t)(unsigned long)piod.piod_offs;
563 		uio.uio_resid = piod.piod_len;
564 		uio.uio_vmspace = vm;
565 
566 		error = process_domem(l, lt, &uio);
567 		piod.piod_len -= uio.uio_resid;
568 		(void) copyout(&piod, SCARG(uap, addr), sizeof(piod));
569 		uvmspace_free(vm);
570 		break;
571 
572 	case  PT_DUMPCORE:
573 		if ((path = SCARG(uap, addr)) != NULL) {
574 			char *dst;
575 			len = SCARG(uap, data);
576 
577 			if (len < 0 || len >= MAXPATHLEN) {
578 				error = EINVAL;
579 				break;
580 			}
581 			dst = kmem_alloc(len + 1, KM_SLEEP);
582 			if ((error = copyin(path, dst, len)) != 0) {
583 				kmem_free(dst, len + 1);
584 				break;
585 			}
586 			path = dst;
587 			path[len] = '\0';
588 		}
589 		error = (*coredump_vec)(lt, path);
590 		if (path)
591 			kmem_free(path, len + 1);
592 		break;
593 
594 #ifdef PT_STEP
595 	case  PT_STEP:
596 		/*
597 		 * From the 4.4BSD PRM:
598 		 * "Execution continues as in request PT_CONTINUE; however
599 		 * as soon as possible after execution of at least one
600 		 * instruction, execution stops again. [ ... ]"
601 		 */
602 #endif
603 	case  PT_CONTINUE:
604 	case  PT_SYSCALL:
605 	case  PT_DETACH:
606 		if (req == PT_SYSCALL) {
607 			if (!ISSET(t->p_slflag, PSL_SYSCALL)) {
608 				SET(t->p_slflag, PSL_SYSCALL);
609 #ifdef __HAVE_SYSCALL_INTERN
610 				(*t->p_emul->e_syscall_intern)(t);
611 #endif
612 			}
613 		} else {
614 			if (ISSET(t->p_slflag, PSL_SYSCALL)) {
615 				CLR(t->p_slflag, PSL_SYSCALL);
616 #ifdef __HAVE_SYSCALL_INTERN
617 				(*t->p_emul->e_syscall_intern)(t);
618 #endif
619 			}
620 		}
621 		t->p_trace_enabled = trace_is_enabled(t);
622 
623 		/*
624 		 * Pick up the LWPID, if supplied.  There are two cases:
625 		 * data < 0 : step or continue single thread, lwp = -data
626 		 * data > 0 in PT_STEP : step this thread, continue others
627 		 * For operations other than PT_STEP, data > 0 means
628 		 * data is the signo to deliver to the process.
629 		 */
630 		tmp = SCARG(uap, data);
631 		if (tmp >= 0) {
632 #ifdef PT_STEP
633 			if (req == PT_STEP)
634 				signo = 0;
635 			else
636 #endif
637 			{
638 				signo = tmp;
639 				tmp = 0;	/* don't search for LWP */
640 			}
641 		}
642 		else
643 			tmp = -tmp;
644 
645 		if (tmp > 0) {
646 			if (req == PT_DETACH) {
647 				error = EINVAL;
648 				break;
649 			}
650 			lwp_delref2 (lt);
651 			lt = lwp_find(t, tmp);
652 			if (lt == NULL) {
653 				error = ESRCH;
654 				break;
655 			}
656 			lwp_addref(lt);
657 			resume_all = 0;
658 			signo = 0;
659 		}
660 
661 		/*
662 		 * From the 4.4BSD PRM:
663 		 * "The data argument is taken as a signal number and the
664 		 * child's execution continues at location addr as if it
665 		 * incurred that signal.  Normally the signal number will
666 		 * be either 0 to indicate that the signal that caused the
667 		 * stop should be ignored, or that value fetched out of
668 		 * the process's image indicating which signal caused
669 		 * the stop.  If addr is (int *)1 then execution continues
670 		 * from where it stopped."
671 		 */
672 
673 		/* Check that the data is a valid signal number or zero. */
674 		if (signo < 0 || signo >= NSIG) {
675 			error = EINVAL;
676 			break;
677 		}
678 
679 		/* If the address parameter is not (int *)1, set the pc. */
680 		if ((int *)SCARG(uap, addr) != (int *)1) {
681 			error = process_set_pc(lt, SCARG(uap, addr));
682 			if (error != 0)
683 				break;
684 		}
685 #ifdef PT_STEP
686 		/*
687 		 * Arrange for a single-step, if that's requested and possible.
688 		 * More precisely, set the single step status as requested for
689 		 * the requested thread, and clear it for other threads.
690 		 */
691 		LIST_FOREACH(lt2, &t->p_lwps, l_sibling) {
692 			if (lt != lt2)
693 			{
694 				lwp_lock(lt2);
695 				process_sstep(lt2, 0);
696 				lwp_unlock(lt2);
697 			}
698 		}
699 		error = process_sstep(lt, req == PT_STEP);
700 		if (error)
701 			break;
702 #endif
703 		if (req == PT_DETACH) {
704 			CLR(t->p_slflag, PSL_TRACED|PSL_FSTRACE|PSL_SYSCALL);
705 
706 			/* give process back to original parent or init */
707 			if (t->p_opptr != t->p_pptr) {
708 				struct proc *pp = t->p_opptr;
709 				proc_reparent(t, pp ? pp : initproc);
710 			}
711 
712 			/* not being traced any more */
713 			t->p_opptr = NULL;
714 		}
715 	sendsig:
716 		t->p_fpid = 0;
717 		/* Finally, deliver the requested signal (or none). */
718 		if (t->p_stat == SSTOP) {
719 			/*
720 			 * Unstop the process.  If it needs to take a
721 			 * signal, make all efforts to ensure that at
722 			 * an LWP runs to see it.
723 			 */
724 			t->p_xstat = signo;
725 			if (resume_all)
726 				proc_unstop(t);
727 			else
728 				lwp_unstop(lt);
729 		} else if (signo != 0) {
730 			KSI_INIT_EMPTY(&ksi);
731 			ksi.ksi_signo = signo;
732 			kpsignal2(t, &ksi);
733 		}
734 		break;
735 
736 	case  PT_SYSCALLEMU:
737 		if (!ISSET(t->p_slflag, PSL_SYSCALL) || t->p_stat != SSTOP) {
738 			error = EINVAL;
739 			break;
740 		}
741 		SET(t->p_slflag, PSL_SYSCALLEMU);
742 		break;
743 
744 	case  PT_KILL:
745 		/* just send the process a KILL signal. */
746 		signo = SIGKILL;
747 		goto sendsig;	/* in PT_CONTINUE, above. */
748 
749 	case  PT_ATTACH:
750 		/*
751 		 * Go ahead and set the trace flag.
752 		 * Save the old parent (it's reset in
753 		 *   _DETACH, and also in kern_exit.c:wait4()
754 		 * Reparent the process so that the tracing
755 		 *   proc gets to see all the action.
756 		 * Stop the target.
757 		 */
758 		t->p_opptr = t->p_pptr;
759 		if (t->p_pptr != p) {
760 			struct proc *parent = t->p_pptr;
761 
762 			if (parent->p_lock < t->p_lock) {
763 				if (!mutex_tryenter(parent->p_lock)) {
764 					mutex_exit(t->p_lock);
765 					mutex_enter(parent->p_lock);
766 				}
767 			} else if (parent->p_lock > t->p_lock) {
768 				mutex_enter(parent->p_lock);
769 			}
770 			parent->p_slflag |= PSL_CHTRACED;
771 			proc_reparent(t, p);
772 			if (parent->p_lock != t->p_lock)
773 				mutex_exit(parent->p_lock);
774 		}
775 		SET(t->p_slflag, PSL_TRACED);
776 		signo = SIGSTOP;
777 		goto sendsig;
778 
779 	case  PT_GET_EVENT_MASK:
780 		if (SCARG(uap, data) != sizeof(pe)) {
781 			DPRINTF(("ptrace(%d): %d != %zu\n", req,
782 			    SCARG(uap, data), sizeof(pe)));
783 			error = EINVAL;
784 			break;
785 		}
786 		memset(&pe, 0, sizeof(pe));
787 		pe.pe_set_event = ISSET(t->p_slflag, PSL_TRACEFORK) ?
788 		    PTRACE_FORK : 0;
789 		error = copyout(&pe, SCARG(uap, addr), sizeof(pe));
790 		break;
791 
792 	case  PT_SET_EVENT_MASK:
793 		if (SCARG(uap, data) != sizeof(pe)) {
794 			DPRINTF(("ptrace(%d): %d != %zu\n", req,
795 			    SCARG(uap, data), sizeof(pe)));
796 			error = EINVAL;
797 			break;
798 		}
799 		if ((error = copyin(SCARG(uap, addr), &pe, sizeof(pe))) != 0)
800 			return error;
801 		if (pe.pe_set_event & PTRACE_FORK)
802 			SET(t->p_slflag, PSL_TRACEFORK);
803 		else
804 			CLR(t->p_slflag, PSL_TRACEFORK);
805 		break;
806 
807 	case  PT_GET_PROCESS_STATE:
808 		if (SCARG(uap, data) != sizeof(ps)) {
809 			DPRINTF(("ptrace(%d): %d != %zu\n", req,
810 			    SCARG(uap, data), sizeof(ps)));
811 			error = EINVAL;
812 			break;
813 		}
814 		memset(&ps, 0, sizeof(ps));
815 		if (t->p_fpid) {
816 			ps.pe_report_event = PTRACE_FORK;
817 			ps.pe_other_pid = t->p_fpid;
818 		}
819 		error = copyout(&ps, SCARG(uap, addr), sizeof(ps));
820 		break;
821 
822 	case PT_LWPINFO:
823 		if (SCARG(uap, data) != sizeof(pl)) {
824 			DPRINTF(("ptrace(%d): %d != %zu\n", req,
825 			    SCARG(uap, data), sizeof(pl)));
826 			error = EINVAL;
827 			break;
828 		}
829 		error = copyin(SCARG(uap, addr), &pl, sizeof(pl));
830 		if (error)
831 			break;
832 		tmp = pl.pl_lwpid;
833 		lwp_delref(lt);
834 		mutex_enter(t->p_lock);
835 		if (tmp == 0)
836 			lt = lwp_find_first(t);
837 		else {
838 			lt = lwp_find(t, tmp);
839 			if (lt == NULL) {
840 				mutex_exit(t->p_lock);
841 				error = ESRCH;
842 				break;
843 			}
844 			lt = LIST_NEXT(lt, l_sibling);
845 		}
846 		while (lt != NULL && !lwp_alive(lt))
847 			lt = LIST_NEXT(lt, l_sibling);
848 		pl.pl_lwpid = 0;
849 		pl.pl_event = 0;
850 		if (lt) {
851 			lwp_addref(lt);
852 			pl.pl_lwpid = lt->l_lid;
853 			if (lt->l_lid == t->p_sigctx.ps_lwp)
854 				pl.pl_event = PL_EVENT_SIGNAL;
855 		}
856 		mutex_exit(t->p_lock);
857 
858 		error = copyout(&pl, SCARG(uap, addr), sizeof(pl));
859 		break;
860 
861 #ifdef PT_SETREGS
862 	case  PT_SETREGS:
863 		write = 1;
864 #endif
865 #ifdef PT_GETREGS
866 	case  PT_GETREGS:
867 		/* write = 0 done above. */
868 #endif
869 #if defined(PT_SETREGS) || defined(PT_GETREGS)
870 		tmp = SCARG(uap, data);
871 		if (tmp != 0 && t->p_nlwps > 1) {
872 			lwp_delref(lt);
873 			mutex_enter(t->p_lock);
874 			lt = lwp_find(t, tmp);
875 			if (lt == NULL) {
876 				mutex_exit(t->p_lock);
877 				error = ESRCH;
878 				break;
879 			}
880 			lwp_addref(lt);
881 			mutex_exit(t->p_lock);
882 		}
883 		if (!process_validregs(lt))
884 			error = EINVAL;
885 		else {
886 			error = proc_vmspace_getref(l->l_proc, &vm);
887 			if (error)
888 				break;
889 			iov.iov_base = SCARG(uap, addr);
890 			iov.iov_len = sizeof(struct reg);
891 			uio.uio_iov = &iov;
892 			uio.uio_iovcnt = 1;
893 			uio.uio_offset = 0;
894 			uio.uio_resid = sizeof(struct reg);
895 			uio.uio_rw = write ? UIO_WRITE : UIO_READ;
896 			uio.uio_vmspace = vm;
897 
898 			error = process_doregs(l, lt, &uio);
899 			uvmspace_free(vm);
900 		}
901 		break;
902 #endif
903 
904 #ifdef PT_SETFPREGS
905 	case  PT_SETFPREGS:
906 		write = 1;
907 #endif
908 #ifdef PT_GETFPREGS
909 	case  PT_GETFPREGS:
910 		/* write = 0 done above. */
911 #endif
912 #if defined(PT_SETFPREGS) || defined(PT_GETFPREGS)
913 		tmp = SCARG(uap, data);
914 		if (tmp != 0 && t->p_nlwps > 1) {
915 			lwp_delref(lt);
916 			mutex_enter(t->p_lock);
917 			lt = lwp_find(t, tmp);
918 			if (lt == NULL) {
919 				mutex_exit(t->p_lock);
920 				error = ESRCH;
921 				break;
922 			}
923 			lwp_addref(lt);
924 			mutex_exit(t->p_lock);
925 		}
926 		if (!process_validfpregs(lt))
927 			error = EINVAL;
928 		else {
929 			error = proc_vmspace_getref(l->l_proc, &vm);
930 			if (error)
931 				break;
932 			iov.iov_base = SCARG(uap, addr);
933 			iov.iov_len = sizeof(struct fpreg);
934 			uio.uio_iov = &iov;
935 			uio.uio_iovcnt = 1;
936 			uio.uio_offset = 0;
937 			uio.uio_resid = sizeof(struct fpreg);
938 			uio.uio_rw = write ? UIO_WRITE : UIO_READ;
939 			uio.uio_vmspace = vm;
940 
941 			error = process_dofpregs(l, lt, &uio);
942 			uvmspace_free(vm);
943 		}
944 		break;
945 #endif
946 
947 #ifdef __HAVE_PTRACE_MACHDEP
948 	PTRACE_MACHDEP_REQUEST_CASES
949 		error = ptrace_machdep_dorequest(l, lt,
950 		    req, SCARG(uap, addr), SCARG(uap, data));
951 		break;
952 #endif
953 	}
954 
955 	if (pheld) {
956 		mutex_exit(t->p_lock);
957 		mutex_exit(proc_lock);
958 	}
959 	if (lt != NULL)
960 		lwp_delref(lt);
961 	rw_exit(&t->p_reflock);
962 
963 	return error;
964 }
965 
966 int
967 process_doregs(struct lwp *curl /*tracer*/,
968     struct lwp *l /*traced*/,
969     struct uio *uio)
970 {
971 #if defined(PT_GETREGS) || defined(PT_SETREGS)
972 	int error;
973 	struct reg r;
974 	char *kv;
975 	int kl;
976 
977 	if (uio->uio_offset < 0 || uio->uio_offset > (off_t)sizeof(r))
978 		return EINVAL;
979 
980 	kl = sizeof(r);
981 	kv = (char *)&r;
982 
983 	kv += uio->uio_offset;
984 	kl -= uio->uio_offset;
985 	if ((size_t)kl > uio->uio_resid)
986 		kl = uio->uio_resid;
987 
988 	error = process_read_regs(l, &r);
989 	if (error == 0)
990 		error = uiomove(kv, kl, uio);
991 	if (error == 0 && uio->uio_rw == UIO_WRITE) {
992 		if (l->l_stat != LSSTOP)
993 			error = EBUSY;
994 		else
995 			error = process_write_regs(l, &r);
996 	}
997 
998 	uio->uio_offset = 0;
999 	return (error);
1000 #else
1001 	return (EINVAL);
1002 #endif
1003 }
1004 
1005 int
1006 process_validregs(struct lwp *l)
1007 {
1008 
1009 #if defined(PT_SETREGS) || defined(PT_GETREGS)
1010 	return ((l->l_flag & LW_SYSTEM) == 0);
1011 #else
1012 	return (0);
1013 #endif
1014 }
1015 
1016 int
1017 process_dofpregs(struct lwp *curl /*tracer*/,
1018     struct lwp *l /*traced*/,
1019     struct uio *uio)
1020 {
1021 #if defined(PT_GETFPREGS) || defined(PT_SETFPREGS)
1022 	int error;
1023 	struct fpreg r;
1024 	char *kv;
1025 	size_t kl;
1026 
1027 	if (uio->uio_offset < 0 || uio->uio_offset > (off_t)sizeof(r))
1028 		return EINVAL;
1029 
1030 	kl = sizeof(r);
1031 	kv = (char *)&r;
1032 
1033 	kv += uio->uio_offset;
1034 	kl -= uio->uio_offset;
1035 	if (kl > uio->uio_resid)
1036 		kl = uio->uio_resid;
1037 
1038 	error = process_read_fpregs(l, &r, &kl);
1039 	if (error == 0)
1040 		error = uiomove(kv, kl, uio);
1041 	if (error == 0 && uio->uio_rw == UIO_WRITE) {
1042 		if (l->l_stat != LSSTOP)
1043 			error = EBUSY;
1044 		else
1045 			error = process_write_fpregs(l, &r, kl);
1046 	}
1047 	uio->uio_offset = 0;
1048 	return (error);
1049 #else
1050 	return (EINVAL);
1051 #endif
1052 }
1053 
1054 int
1055 process_validfpregs(struct lwp *l)
1056 {
1057 
1058 #if defined(PT_SETFPREGS) || defined(PT_GETFPREGS)
1059 	return ((l->l_flag & LW_SYSTEM) == 0);
1060 #else
1061 	return (0);
1062 #endif
1063 }
1064 #endif /* PTRACE */
1065 
1066 #if defined(KTRACE) || defined(PTRACE)
1067 int
1068 process_domem(struct lwp *curl /*tracer*/,
1069     struct lwp *l /*traced*/,
1070     struct uio *uio)
1071 {
1072 	struct proc *p = l->l_proc;	/* traced */
1073 	struct vmspace *vm;
1074 	int error;
1075 
1076 	size_t len;
1077 #ifdef PMAP_NEED_PROCWR
1078 	vaddr_t	addr;
1079 #endif
1080 
1081 	error = 0;
1082 	len = uio->uio_resid;
1083 
1084 	if (len == 0)
1085 		return (0);
1086 
1087 #ifdef PMAP_NEED_PROCWR
1088 	addr = uio->uio_offset;
1089 #endif
1090 
1091 	vm = p->p_vmspace;
1092 
1093 	mutex_enter(&vm->vm_map.misc_lock);
1094 	if ((l->l_flag & LW_WEXIT) || vm->vm_refcnt < 1)
1095 		error = EFAULT;
1096 	if (error == 0)
1097 		p->p_vmspace->vm_refcnt++;  /* XXX */
1098 	mutex_exit(&vm->vm_map.misc_lock);
1099 	if (error != 0)
1100 		return (error);
1101 	error = uvm_io(&vm->vm_map, uio);
1102 	uvmspace_free(vm);
1103 
1104 #ifdef PMAP_NEED_PROCWR
1105 	if (error == 0 && uio->uio_rw == UIO_WRITE)
1106 		pmap_procwr(p, addr, len);
1107 #endif
1108 	return (error);
1109 }
1110 #endif /* KTRACE || PTRACE */
1111 
1112 #if defined(KTRACE) || defined(PTRACE)
1113 void
1114 process_stoptrace(void)
1115 {
1116 	struct lwp *l = curlwp;
1117 	struct proc *p = l->l_proc, *pp;
1118 
1119 	mutex_enter(proc_lock);
1120 	mutex_enter(p->p_lock);
1121 	pp = p->p_pptr;
1122 	if (pp->p_pid == 1) {
1123 		CLR(p->p_slflag, PSL_SYSCALL);	/* XXXSMP */
1124 		mutex_exit(p->p_lock);
1125 		mutex_exit(proc_lock);
1126 		return;
1127 	}
1128 
1129 	p->p_xstat = SIGTRAP;
1130 	proc_stop(p, 1, SIGSTOP);
1131 	mutex_exit(proc_lock);
1132 
1133 	if (sigispending(l, 0)) {
1134 		lwp_lock(l);
1135 		l->l_flag |= LW_PENDSIG;
1136 		lwp_unlock(l);
1137 	}
1138 	mutex_exit(p->p_lock);
1139 }
1140 #endif	/* KTRACE || PTRACE */
1141