xref: /dragonfly/sys/kern/kern_ktrace.c (revision 73610d44) 
1 /*
2  * Copyright (c) 1989, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 3. Neither the name of the University nor the names of its contributors
14  *    may be used to endorse or promote products derived from this software
15  *    without specific prior written permission.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  *
29  *	@(#)kern_ktrace.c	8.2 (Berkeley) 9/23/93
30  * $FreeBSD: src/sys/kern/kern_ktrace.c,v 1.35.2.6 2002/07/05 22:36:38 darrenr Exp $
31  */
32 
33 #include "opt_ktrace.h"
34 
35 #include <sys/param.h>
36 #include <sys/systm.h>
37 #include <sys/sysproto.h>
38 #include <sys/kernel.h>
39 #include <sys/proc.h>
40 #include <sys/fcntl.h>
41 #include <sys/lock.h>
42 #include <sys/nlookup.h>
43 #include <sys/vnode.h>
44 #include <sys/ktrace.h>
45 #include <sys/malloc.h>
46 #include <sys/syslog.h>
47 #include <sys/sysent.h>
48 
49 #include <vm/vm_zone.h>
50 
51 #include <sys/mplock2.h>
52 
53 static MALLOC_DEFINE(M_KTRACE, "KTRACE", "KTRACE");
54 
55 #ifdef KTRACE
56 static void ktrgetheader (struct ktr_header *kth, int type);
57 static struct ktr_syscall *ktrgetsyscall(struct ktr_header *kth,
58 				struct ktr_syscall *ktp_cache, int narg);
59 static void ktrputsyscall(struct ktr_syscall *ktp_cache,
60 				struct ktr_syscall *ktp);
61 static void ktrwrite (struct lwp *, struct ktr_header *, struct uio *);
62 static int ktrcanset (struct thread *,struct proc *);
63 static int ktrsetchildren (struct thread *, struct proc *,
64 				int, int, ktrace_node_t);
65 static int ktrops (struct thread *,struct proc *,int,int, ktrace_node_t);
66 
67 /*
68  * MPSAFE
69  */
70 static
71 void
72 ktrgetheader(struct ktr_header *kth, int type)
73 {
74 	thread_t td = curthread;
75 	struct proc *p = td->td_proc;
76 	struct lwp *lp = td->td_lwp;
77 
78 	kth->ktr_type = type;
79 	/* XXX threaded flag is a hack at the moment */
80 	kth->ktr_flags = (p->p_nthreads > 1) ? KTRH_THREADED : 0;
81 	kth->ktr_flags |= KTRH_CPUID_ENCODE(td->td_gd->gd_cpuid);
82 	/*microtime(&kth->ktr_time); set in ktrwrite */
83 	kth->ktr_pid = p->p_pid;
84 	kth->ktr_tid = lp->lwp_tid;
85 	bcopy(p->p_comm, kth->ktr_comm, MAXCOMLEN + 1);
86 }
87 
88 static
89 struct ktr_syscall *
90 ktrgetsyscall(struct ktr_header *kth, struct ktr_syscall *ktp_cache, int narg)
91 {
92 	size_t len;
93 
94 	len = offsetof(struct ktr_syscall, ktr_args[narg]);
95 	if (len > sizeof(*ktp_cache))
96 		ktp_cache = kmalloc(len, M_KTRACE, M_WAITOK);
97 	kth->ktr_buf = (caddr_t)ktp_cache;
98 	kth->ktr_len = (int)len;
99 	return (ktp_cache);
100 }
101 
102 static
103 void
104 ktrputsyscall(struct ktr_syscall *ktp_cache, struct ktr_syscall *ktp)
105 {
106 	if (ktp != ktp_cache)
107 		kfree(ktp, M_KTRACE);
108 }
109 
110 void
111 ktrsyscall(struct lwp *lp, int code, int narg, register_t args[])
112 {
113 	struct ktr_header kth;
114 	struct ktr_syscall ktp_cache;
115 	struct ktr_syscall *ktp;
116 	register_t *argp;
117 	int i;
118 
119 	/*
120 	 * Setting the active bit prevents a ktrace recursion from the
121 	 * ktracing op itself.
122 	 */
123 	lp->lwp_traceflag |= KTRFAC_ACTIVE;
124 	ktrgetheader(&kth, KTR_SYSCALL);
125 
126 	ktp = ktrgetsyscall(&kth, &ktp_cache, narg);
127 	ktp->ktr_code = code;
128 	ktp->ktr_narg = narg;
129 	argp = &ktp->ktr_args[0];
130 	for (i = 0; i < narg; i++)
131 		*argp++ = args[i];
132 	ktrwrite(lp, &kth, NULL);
133 
134 	ktrputsyscall(&ktp_cache, ktp);
135 	lp->lwp_traceflag &= ~KTRFAC_ACTIVE;
136 }
137 
138 void
139 ktrsysret(struct lwp *lp, int code, int error, register_t retval)
140 {
141 	struct ktr_header kth;
142 	struct ktr_sysret ktp;
143 
144 	lp->lwp_traceflag |= KTRFAC_ACTIVE;
145 	ktrgetheader(&kth, KTR_SYSRET);
146 
147 	ktp.ktr_code = code;
148 	ktp.ktr_error = error;
149 	if (error == 0)
150 		ktp.ktr_retval = retval;		/* what about val2 ? */
151 	else
152 		ktp.ktr_retval = 0;
153 
154 	kth.ktr_buf = (caddr_t)&ktp;
155 	kth.ktr_len = (int)sizeof(struct ktr_sysret);
156 
157 	ktrwrite(lp, &kth, NULL);
158 	lp->lwp_traceflag &= ~KTRFAC_ACTIVE;
159 }
160 
161 void
162 ktrnamei(struct lwp *lp, char *path)
163 {
164 	struct ktr_header kth;
165 
166 	lp->lwp_traceflag |= KTRFAC_ACTIVE;
167 	ktrgetheader(&kth, KTR_NAMEI);
168 
169 	kth.ktr_len = (int)strlen(path);
170 	kth.ktr_buf = path;
171 
172 	ktrwrite(lp, &kth, NULL);
173 	lp->lwp_traceflag &= ~KTRFAC_ACTIVE;
174 }
175 
176 void
177 ktrgenio(struct lwp *lp, int fd, enum uio_rw rw, struct uio *uio, int error)
178 {
179 	struct ktr_header kth;
180 	struct ktr_genio ktg;
181 
182 	if (error)
183 		return;
184 	lp->lwp_traceflag |= KTRFAC_ACTIVE;
185 	ktrgetheader(&kth, KTR_GENIO);
186 
187 	ktg.ktr_fd = fd;
188 	ktg.ktr_rw = rw;
189 	kth.ktr_buf = (caddr_t)&ktg;
190 	kth.ktr_len = (int)sizeof(struct ktr_genio);
191 	uio->uio_offset = 0;
192 	uio->uio_rw = UIO_WRITE;
193 
194 	ktrwrite(lp, &kth, uio);
195 	lp->lwp_traceflag &= ~KTRFAC_ACTIVE;
196 }
197 
198 void
199 ktrpsig(struct lwp *lp, int sig, sig_t action, sigset_t *mask, int code)
200 {
201 	struct ktr_header kth;
202 	struct ktr_psig	kp;
203 
204 	lp->lwp_traceflag |= KTRFAC_ACTIVE;
205 	ktrgetheader(&kth, KTR_PSIG);
206 
207 	kp.signo = (char)sig;
208 	kp.action = action;
209 	kp.mask = *mask;
210 	kp.code = code;
211 	kth.ktr_buf = (caddr_t)&kp;
212 	kth.ktr_len = (int)sizeof(struct ktr_psig);
213 
214 	ktrwrite(lp, &kth, NULL);
215 	lp->lwp_traceflag &= ~KTRFAC_ACTIVE;
216 }
217 
218 void
219 ktrcsw(struct lwp *lp, int out, int user)
220 {
221 	struct ktr_header kth;
222 	struct ktr_csw kc;
223 
224 	lp->lwp_traceflag |= KTRFAC_ACTIVE;
225 	ktrgetheader(&kth, KTR_CSW);
226 
227 	kc.out = out;
228 	kc.user = user;
229 	kth.ktr_buf = (caddr_t)&kc;
230 	kth.ktr_len = (int)sizeof(struct ktr_csw);
231 
232 	ktrwrite(lp, &kth, NULL);
233 	lp->lwp_traceflag &= ~KTRFAC_ACTIVE;
234 }
235 #endif
236 
237 /* Interface and common routines */
238 
239 #ifdef KTRACE
240 /*
241  * ktrace system call
242  */
243 struct ktrace_clear_info {
244 	ktrace_node_t tracenode;
245 	int rootclear;
246 	int error;
247 };
248 
249 static int ktrace_clear_callback(struct proc *p, void *data);
250 
251 #endif
252 
253 /*
254  * MPALMOSTSAFE
255  */
256 int
257 sys_ktrace(struct ktrace_args *uap)
258 {
259 #ifdef KTRACE
260 	struct ktrace_clear_info info;
261 	struct thread *td = curthread;
262 	struct proc *curp = td->td_proc;
263 	struct proc *p;
264 	struct pgrp *pg;
265 	int facs = uap->facs & ~KTRFAC_ROOT;
266 	int ops = KTROP(uap->ops);
267 	int descend = uap->ops & KTRFLAG_DESCEND;
268 	int ret = 0;
269 	int error = 0;
270 	struct nlookupdata nd;
271 	ktrace_node_t tracenode = NULL;
272 
273 	get_mplock();
274 	curp->p_traceflag |= KTRFAC_ACTIVE;
275 	if (ops != KTROP_CLEAR) {
276 		/*
277 		 * an operation which requires a file argument.
278 		 */
279 		error = nlookup_init(&nd, uap->fname,
280 					UIO_USERSPACE, NLC_LOCKVP);
281 		if (error == 0)
282 			error = vn_open(&nd, NULL, FREAD|FWRITE|O_NOFOLLOW, 0);
283 		if (error == 0 && nd.nl_open_vp->v_type != VREG)
284 			error = EACCES;
285 		if (error) {
286 			curp->p_traceflag &= ~KTRFAC_ACTIVE;
287 			nlookup_done(&nd);
288 			goto done;
289 		}
290 		tracenode = kmalloc(sizeof(struct ktrace_node), M_KTRACE,
291 				    M_WAITOK | M_ZERO);
292 		tracenode->kn_vp = nd.nl_open_vp;
293 		tracenode->kn_refs = 1;
294 		nd.nl_open_vp = NULL;
295 		nlookup_done(&nd);
296 		vn_unlock(tracenode->kn_vp);
297 	}
298 	/*
299 	 * Clear all uses of the tracefile.  Not the most efficient operation
300 	 * in the world.
301 	 */
302 	if (ops == KTROP_CLEARFILE) {
303 		info.tracenode = tracenode;
304 		info.error = 0;
305 		info.rootclear = 0;
306 		allproc_scan(ktrace_clear_callback, &info);
307 		error = info.error;
308 		goto done;
309 	}
310 	/*
311 	 * need something to (un)trace (XXX - why is this here?)
312 	 */
313 	if (!facs) {
314 		error = EINVAL;
315 		goto done;
316 	}
317 	/*
318 	 * do it
319 	 */
320 	if (uap->pid < 0) {
321 		/*
322 		 * By process group.  Process group is referenced, preventing
323 		 * disposal.
324 		 */
325 		pg = pgfind(-uap->pid);
326 		if (pg == NULL) {
327 			error = ESRCH;
328 			goto done;
329 		}
330 		lwkt_gettoken(&pg->pg_token);
331 		LIST_FOREACH(p, &pg->pg_members, p_pglist) {
332 			PHOLD(p);
333 			if (descend)
334 				ret |= ktrsetchildren(td, p, ops, facs, tracenode);
335 			else
336 				ret |= ktrops(td, p, ops, facs, tracenode);
337 			PRELE(p);
338 		}
339 		lwkt_reltoken(&pg->pg_token);
340 		pgrel(pg);
341 	} else {
342 		/*
343 		 * by pid
344 		 */
345 		p = pfind(uap->pid);
346 		if (p == NULL) {
347 			error = ESRCH;
348 			goto done;
349 		}
350 		if (descend)
351 			ret |= ktrsetchildren(td, p, ops, facs, tracenode);
352 		else
353 			ret |= ktrops(td, p, ops, facs, tracenode);
354 		PRELE(p);
355 	}
356 	if (!ret)
357 		error = EPERM;
358 done:
359 	if (tracenode)
360 		ktrdestroy(&tracenode);
361 	curp->p_traceflag &= ~KTRFAC_ACTIVE;
362 	rel_mplock();
363 	return (error);
364 #else
365 	return ENOSYS;
366 #endif
367 }
368 
369 #ifdef KTRACE
370 
371 /*
372  * NOTE: NOT MPSAFE (yet)
373  */
374 static int
375 ktrace_clear_callback(struct proc *p, void *data)
376 {
377 	struct ktrace_clear_info *info = data;
378 
379 	if (p->p_tracenode) {
380 		if (info->rootclear) {
381 			if (p->p_tracenode == info->tracenode) {
382 				ktrdestroy(&p->p_tracenode);
383 				p->p_traceflag = 0;
384 			}
385 		} else {
386 			if (p->p_tracenode->kn_vp == info->tracenode->kn_vp) {
387 				if (ktrcanset(curthread, p)) {
388 					ktrdestroy(&p->p_tracenode);
389 					p->p_traceflag = 0;
390 				} else {
391 					info->error = EPERM;
392 				}
393 			}
394 		}
395 	}
396 	return(0);
397 }
398 
399 #endif
400 
401 /*
402  * utrace system call
403  *
404  * MPALMOSTSAFE
405  */
406 int
407 sys_utrace(struct utrace_args *uap)
408 {
409 #ifdef KTRACE
410 	struct ktr_header kth;
411 	struct thread *td = curthread;	/* XXX */
412 	char cp_cache[64];
413 	caddr_t cp;
414 
415 	if (!KTRPOINT(td, KTR_USER))
416 		return (0);
417 	if (uap->len > KTR_USER_MAXLEN)
418 		return (EINVAL);
419 	td->td_lwp->lwp_traceflag |= KTRFAC_ACTIVE;
420 	ktrgetheader(&kth, KTR_USER);
421 	if (uap->len <= sizeof(cp_cache))
422 		cp = cp_cache;
423 	else
424 		cp = kmalloc(uap->len, M_KTRACE, M_WAITOK);
425 
426 	if (!copyin(uap->addr, cp, uap->len)) {
427 		kth.ktr_buf = cp;
428 		kth.ktr_len = uap->len;
429 		ktrwrite(td->td_lwp, &kth, NULL);
430 	}
431 	if (cp != cp_cache)
432 		kfree(cp, M_KTRACE);
433 	td->td_lwp->lwp_traceflag &= ~KTRFAC_ACTIVE;
434 
435 	return (0);
436 #else
437 	return (ENOSYS);
438 #endif
439 }
440 
441 void
442 ktrdestroy(struct ktrace_node **tracenodep)
443 {
444 	ktrace_node_t tracenode;
445 
446 	if ((tracenode = *tracenodep) != NULL) {
447 		*tracenodep = NULL;
448 		KKASSERT(tracenode->kn_refs > 0);
449 		if (atomic_fetchadd_int(&tracenode->kn_refs, -1) == 1) {
450 			vn_close(tracenode->kn_vp, FREAD|FWRITE, NULL);
451 			tracenode->kn_vp = NULL;
452 			kfree(tracenode, M_KTRACE);
453 		}
454 	}
455 }
456 
457 /*
458  * This allows a process to inherit a ref on a tracenode and is also used
459  * as a temporary ref to prevent a tracenode from being destroyed out from
460  * under an active operation.
461  */
462 ktrace_node_t
463 ktrinherit(ktrace_node_t tracenode)
464 {
465 	if (tracenode) {
466 		KKASSERT(tracenode->kn_refs > 0);
467 		atomic_add_int(&tracenode->kn_refs, 1);
468 	}
469 	return(tracenode);
470 }
471 
472 #ifdef KTRACE
473 static int
474 ktrops(struct thread *td, struct proc *p, int ops, int facs,
475        ktrace_node_t tracenode)
476 {
477 	ktrace_node_t oldnode;
478 
479 	if (!ktrcanset(td, p))
480 		return (0);
481 	if (ops == KTROP_SET) {
482 		if ((oldnode = p->p_tracenode) != tracenode) {
483 			p->p_tracenode = ktrinherit(tracenode);
484 			ktrdestroy(&oldnode);
485 		}
486 		p->p_traceflag |= facs;
487 		if (td->td_ucred->cr_uid == 0)
488 			p->p_traceflag |= KTRFAC_ROOT;
489 	} else {
490 		/* KTROP_CLEAR */
491 		if (((p->p_traceflag &= ~facs) & KTRFAC_MASK) == 0) {
492 			/* no more tracing */
493 			p->p_traceflag = 0;
494 			ktrdestroy(&p->p_tracenode);
495 		}
496 	}
497 
498 	return (1);
499 }
500 
501 static int
502 ktrsetchildren(struct thread *td, struct proc *top, int ops, int facs,
503 	       ktrace_node_t tracenode)
504 {
505 	struct proc *p;
506 	struct proc *np;
507 	int ret = 0;
508 
509 	p = top;
510 	PHOLD(p);
511 	lwkt_gettoken(&p->p_token);
512 
513 	for (;;) {
514 		ret |= ktrops(td, p, ops, facs, tracenode);
515 
516 		/*
517 		 * If this process has children, descend to them next,
518 		 * otherwise do any siblings, and if done with this level,
519 		 * follow back up the tree (but not past top).
520 		 */
521 		if ((np = LIST_FIRST(&p->p_children)) != NULL) {
522 			PHOLD(np);
523 		}
524 		while (np == NULL) {
525 			if (p == top)
526 				break;
527 			if ((np = LIST_NEXT(p, p_sibling)) != NULL) {
528 				PHOLD(np);
529 				break;
530 			}
531 
532 			/*
533 			 * recurse up to parent, set p in our inner
534 			 * loop when doing this.  np can be NULL if
535 			 * we race a reparenting to init (thus 'top'
536 			 * is skipped past and never encountered).
537 			 */
538 			np = p->p_pptr;
539 			if (np == NULL)
540 				break;
541 			PHOLD(np);
542 			lwkt_reltoken(&p->p_token);
543 			PRELE(p);
544 			p = np;
545 			lwkt_gettoken(&p->p_token);
546 			np = NULL;
547 		}
548 		lwkt_reltoken(&p->p_token);
549 		PRELE(p);
550 		p = np;
551 		if (p == NULL)
552 			break;
553 		/* Already held, but we need the token too */
554 		lwkt_gettoken(&p->p_token);
555 	}
556 	return (ret);
557 }
558 
559 static void
560 ktrwrite(struct lwp *lp, struct ktr_header *kth, struct uio *uio)
561 {
562 	struct ktrace_clear_info info;
563 	struct uio auio;
564 	struct iovec aiov[2];
565 	int error;
566 	ktrace_node_t tracenode;
567 
568 	/*
569 	 * We have to ref our tracenode to prevent it from being ripped out
570 	 * from under us while we are trying to use it.   p_tracenode can
571 	 * go away at any time if another process gets a write error.
572 	 *
573 	 * XXX not MP safe
574 	 */
575 	if (lp->lwp_proc->p_tracenode == NULL)
576 		return;
577 	tracenode = ktrinherit(lp->lwp_proc->p_tracenode);
578 	auio.uio_iov = &aiov[0];
579 	auio.uio_offset = 0;
580 	auio.uio_segflg = UIO_SYSSPACE;
581 	auio.uio_rw = UIO_WRITE;
582 	aiov[0].iov_base = (caddr_t)kth;
583 	aiov[0].iov_len = sizeof(struct ktr_header);
584 	auio.uio_resid = sizeof(struct ktr_header);
585 	auio.uio_iovcnt = 1;
586 	auio.uio_td = curthread;
587 	if (kth->ktr_len > 0) {
588 		auio.uio_iovcnt++;
589 		aiov[1].iov_base = kth->ktr_buf;
590 		aiov[1].iov_len = kth->ktr_len;
591 		auio.uio_resid += kth->ktr_len;
592 		if (uio != NULL)
593 			kth->ktr_len += uio->uio_resid;
594 	}
595 
596 	/*
597 	 * NOTE: Must set timestamp after obtaining lock to ensure no
598 	 * 	 timestamp reversals in the output file.
599 	 */
600 	vn_lock(tracenode->kn_vp, LK_EXCLUSIVE | LK_RETRY);
601 	microtime(&kth->ktr_time);
602 	error = VOP_WRITE(tracenode->kn_vp, &auio,
603 			  IO_UNIT | IO_APPEND, lp->lwp_thread->td_ucred);
604 	if (error == 0 && uio != NULL) {
605 		error = VOP_WRITE(tracenode->kn_vp, uio,
606 			      IO_UNIT | IO_APPEND, lp->lwp_thread->td_ucred);
607 	}
608 	vn_unlock(tracenode->kn_vp);
609 	if (error) {
610 		/*
611 		 * If an error occured, give up tracing on all processes
612 		 * using this tracenode.  This is not MP safe but is
613 		 * blocking-safe.
614 		 */
615 		log(LOG_NOTICE,
616 		    "ktrace write failed, errno %d, tracing stopped\n", error);
617 		info.tracenode = tracenode;
618 		info.error = 0;
619 		info.rootclear = 1;
620 		allproc_scan(ktrace_clear_callback, &info);
621 	}
622 	ktrdestroy(&tracenode);
623 }
624 
625 /*
626  * Return true if caller has permission to set the ktracing state
627  * of target.  Essentially, the target can't possess any
628  * more permissions than the caller.  KTRFAC_ROOT signifies that
629  * root previously set the tracing status on the target process, and
630  * so, only root may further change it.
631  *
632  * TODO: check groups.  use caller effective gid.
633  */
634 static int
635 ktrcanset(struct thread *calltd, struct proc *targetp)
636 {
637 	struct ucred *caller = calltd->td_ucred;
638 	struct ucred *target = targetp->p_ucred;
639 
640 	if (!PRISON_CHECK(caller, target))
641 		return (0);
642 	if ((caller->cr_uid == target->cr_ruid &&
643 	     target->cr_ruid == target->cr_svuid &&
644 	     caller->cr_rgid == target->cr_rgid &&	/* XXX */
645 	     target->cr_rgid == target->cr_svgid &&
646 	     (targetp->p_traceflag & KTRFAC_ROOT) == 0 &&
647 	     (targetp->p_flags & P_SUGID) == 0) ||
648 	     caller->cr_uid == 0)
649 		return (1);
650 
651 	return (0);
652 }
653 
654 #endif /* KTRACE */
655