xref: /openbsd/sys/kern/kern_ktrace.c (revision df930be7) 
1 /*	$NetBSD: kern_ktrace.c,v 1.20 1995/10/07 06:28:16 mycroft Exp $	*/
2 
3 /*
4  * Copyright (c) 1989, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. All advertising materials mentioning features or use of this software
16  *    must display the following acknowledgement:
17  *	This product includes software developed by the University of
18  *	California, Berkeley and its contributors.
19  * 4. Neither the name of the University nor the names of its contributors
20  *    may be used to endorse or promote products derived from this software
21  *    without specific prior written permission.
22  *
23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33  * SUCH DAMAGE.
34  *
35  *	@(#)kern_ktrace.c	8.2 (Berkeley) 9/23/93
36  */
37 
38 #ifdef KTRACE
39 
40 #include <sys/param.h>
41 #include <sys/systm.h>
42 #include <sys/proc.h>
43 #include <sys/file.h>
44 #include <sys/namei.h>
45 #include <sys/vnode.h>
46 #include <sys/ktrace.h>
47 #include <sys/malloc.h>
48 #include <sys/syslog.h>
49 
50 #include <sys/mount.h>
51 #include <sys/syscallargs.h>
52 
53 struct ktr_header *
54 ktrgetheader(type)
55 	int type;
56 {
57 	register struct ktr_header *kth;
58 	struct proc *p = curproc;	/* XXX */
59 
60 	MALLOC(kth, struct ktr_header *, sizeof (struct ktr_header),
61 		M_TEMP, M_WAITOK);
62 	kth->ktr_type = type;
63 	microtime(&kth->ktr_time);
64 	kth->ktr_pid = p->p_pid;
65 	bcopy(p->p_comm, kth->ktr_comm, MAXCOMLEN);
66 	return (kth);
67 }
68 
69 void
70 ktrsyscall(vp, code, argsize, args)
71 	struct vnode *vp;
72 	register_t code;
73 	size_t argsize;
74 	register_t args[];
75 {
76 	struct	ktr_header *kth;
77 	struct	ktr_syscall *ktp;
78 	register len = sizeof(struct ktr_syscall) + argsize;
79 	struct proc *p = curproc;	/* XXX */
80 	register_t *argp;
81 	int i;
82 
83 	p->p_traceflag |= KTRFAC_ACTIVE;
84 	kth = ktrgetheader(KTR_SYSCALL);
85 	MALLOC(ktp, struct ktr_syscall *, len, M_TEMP, M_WAITOK);
86 	ktp->ktr_code = code;
87 	ktp->ktr_argsize = argsize;
88 	argp = (register_t *)((char *)ktp + sizeof(struct ktr_syscall));
89 	for (i = 0; i < (argsize / sizeof *argp); i++)
90 		*argp++ = args[i];
91 	kth->ktr_buf = (caddr_t)ktp;
92 	kth->ktr_len = len;
93 	ktrwrite(vp, kth);
94 	FREE(ktp, M_TEMP);
95 	FREE(kth, M_TEMP);
96 	p->p_traceflag &= ~KTRFAC_ACTIVE;
97 }
98 
99 void
100 ktrsysret(vp, code, error, retval)
101 	struct vnode *vp;
102 	register_t code;
103 	int error;
104 	register_t retval;
105 {
106 	struct ktr_header *kth;
107 	struct ktr_sysret ktp;
108 	struct proc *p = curproc;	/* XXX */
109 
110 	p->p_traceflag |= KTRFAC_ACTIVE;
111 	kth = ktrgetheader(KTR_SYSRET);
112 	ktp.ktr_code = code;
113 	ktp.ktr_error = error;
114 	ktp.ktr_retval = retval;		/* what about val2 ? */
115 
116 	kth->ktr_buf = (caddr_t)&ktp;
117 	kth->ktr_len = sizeof(struct ktr_sysret);
118 
119 	ktrwrite(vp, kth);
120 	FREE(kth, M_TEMP);
121 	p->p_traceflag &= ~KTRFAC_ACTIVE;
122 }
123 
124 void
125 ktrnamei(vp, path)
126 	struct vnode *vp;
127 	char *path;
128 {
129 	struct ktr_header *kth;
130 	struct proc *p = curproc;	/* XXX */
131 
132 	p->p_traceflag |= KTRFAC_ACTIVE;
133 	kth = ktrgetheader(KTR_NAMEI);
134 	kth->ktr_len = strlen(path);
135 	kth->ktr_buf = path;
136 
137 	ktrwrite(vp, kth);
138 	FREE(kth, M_TEMP);
139 	p->p_traceflag &= ~KTRFAC_ACTIVE;
140 }
141 
142 void
143 ktremul(vp, emul)
144 	struct vnode *vp;
145 	char *emul;
146 {
147 	struct ktr_header *kth;
148 	struct proc *p = curproc;       /* XXX */
149 
150 	p->p_traceflag |= KTRFAC_ACTIVE;
151 	kth = ktrgetheader(KTR_EMUL);
152 	kth->ktr_len = strlen(emul);
153 	kth->ktr_buf = emul;
154 
155 	ktrwrite(vp, kth);
156 	FREE(kth, M_TEMP);
157 	p->p_traceflag &= ~KTRFAC_ACTIVE;
158 }
159 
160 void
161 ktrgenio(vp, fd, rw, iov, len, error)
162 	struct vnode *vp;
163 	int fd;
164 	enum uio_rw rw;
165 	register struct iovec *iov;
166 	int len, error;
167 {
168 	struct ktr_header *kth;
169 	register struct ktr_genio *ktp;
170 	register caddr_t cp;
171 	register int resid = len, cnt;
172 	struct proc *p = curproc;	/* XXX */
173 
174 	if (error)
175 		return;
176 	p->p_traceflag |= KTRFAC_ACTIVE;
177 	kth = ktrgetheader(KTR_GENIO);
178 	MALLOC(ktp, struct ktr_genio *, sizeof(struct ktr_genio) + len,
179 		M_TEMP, M_WAITOK);
180 	ktp->ktr_fd = fd;
181 	ktp->ktr_rw = rw;
182 	cp = (caddr_t)((char *)ktp + sizeof (struct ktr_genio));
183 	while (resid > 0) {
184 		if ((cnt = iov->iov_len) > resid)
185 			cnt = resid;
186 		if (copyin(iov->iov_base, cp, (unsigned)cnt))
187 			goto done;
188 		cp += cnt;
189 		resid -= cnt;
190 		iov++;
191 	}
192 	kth->ktr_buf = (caddr_t)ktp;
193 	kth->ktr_len = sizeof (struct ktr_genio) + len;
194 
195 	ktrwrite(vp, kth);
196 done:
197 	FREE(kth, M_TEMP);
198 	FREE(ktp, M_TEMP);
199 	p->p_traceflag &= ~KTRFAC_ACTIVE;
200 }
201 
202 void
203 ktrpsig(vp, sig, action, mask, code)
204 	struct vnode *vp;
205 	int sig;
206 	sig_t action;
207 	int mask, code;
208 {
209 	struct ktr_header *kth;
210 	struct ktr_psig	kp;
211 	struct proc *p = curproc;	/* XXX */
212 
213 	p->p_traceflag |= KTRFAC_ACTIVE;
214 	kth = ktrgetheader(KTR_PSIG);
215 	kp.signo = (char)sig;
216 	kp.action = action;
217 	kp.mask = mask;
218 	kp.code = code;
219 	kth->ktr_buf = (caddr_t)&kp;
220 	kth->ktr_len = sizeof (struct ktr_psig);
221 
222 	ktrwrite(vp, kth);
223 	FREE(kth, M_TEMP);
224 	p->p_traceflag &= ~KTRFAC_ACTIVE;
225 }
226 
227 void
228 ktrcsw(vp, out, user)
229 	struct vnode *vp;
230 	int out, user;
231 {
232 	struct ktr_header *kth;
233 	struct	ktr_csw kc;
234 	struct proc *p = curproc;	/* XXX */
235 
236 	p->p_traceflag |= KTRFAC_ACTIVE;
237 	kth = ktrgetheader(KTR_CSW);
238 	kc.out = out;
239 	kc.user = user;
240 	kth->ktr_buf = (caddr_t)&kc;
241 	kth->ktr_len = sizeof (struct ktr_csw);
242 
243 	ktrwrite(vp, kth);
244 	FREE(kth, M_TEMP);
245 	p->p_traceflag &= ~KTRFAC_ACTIVE;
246 }
247 
248 /* Interface and common routines */
249 
250 /*
251  * ktrace system call
252  */
253 /* ARGSUSED */
254 int
255 sys_ktrace(curp, v, retval)
256 	struct proc *curp;
257 	void *v;
258 	register_t *retval;
259 {
260 	register struct sys_ktrace_args /* {
261 		syscallarg(char *) fname;
262 		syscallarg(int) ops;
263 		syscallarg(int) facs;
264 		syscallarg(int) pid;
265 	} */ *uap = v;
266 	register struct vnode *vp = NULL;
267 	register struct proc *p;
268 	struct pgrp *pg;
269 	int facs = SCARG(uap, facs) & ~KTRFAC_ROOT;
270 	int ops = KTROP(SCARG(uap, ops));
271 	int descend = SCARG(uap, ops) & KTRFLAG_DESCEND;
272 	int ret = 0;
273 	int error = 0;
274 	struct nameidata nd;
275 
276 	curp->p_traceflag |= KTRFAC_ACTIVE;
277 	if (ops != KTROP_CLEAR) {
278 		/*
279 		 * an operation which requires a file argument.
280 		 */
281 		NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, SCARG(uap, fname),
282 		    curp);
283 		if (error = vn_open(&nd, FREAD|FWRITE, 0)) {
284 			curp->p_traceflag &= ~KTRFAC_ACTIVE;
285 			return (error);
286 		}
287 		vp = nd.ni_vp;
288 		VOP_UNLOCK(vp);
289 		if (vp->v_type != VREG) {
290 			(void) vn_close(vp, FREAD|FWRITE, curp->p_ucred, curp);
291 			curp->p_traceflag &= ~KTRFAC_ACTIVE;
292 			return (EACCES);
293 		}
294 	}
295 	/*
296 	 * Clear all uses of the tracefile
297 	 */
298 	if (ops == KTROP_CLEARFILE) {
299 		for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) {
300 			if (p->p_tracep == vp) {
301 				if (ktrcanset(curp, p)) {
302 					p->p_tracep = NULL;
303 					p->p_traceflag = 0;
304 					(void) vn_close(vp, FREAD|FWRITE,
305 						p->p_ucred, p);
306 				} else
307 					error = EPERM;
308 			}
309 		}
310 		goto done;
311 	}
312 	/*
313 	 * need something to (un)trace (XXX - why is this here?)
314 	 */
315 	if (!facs) {
316 		error = EINVAL;
317 		goto done;
318 	}
319 	/*
320 	 * do it
321 	 */
322 	if (SCARG(uap, pid) < 0) {
323 		/*
324 		 * by process group
325 		 */
326 		pg = pgfind(-SCARG(uap, pid));
327 		if (pg == NULL) {
328 			error = ESRCH;
329 			goto done;
330 		}
331 		for (p = pg->pg_members.lh_first; p != 0; p = p->p_pglist.le_next)
332 			if (descend)
333 				ret |= ktrsetchildren(curp, p, ops, facs, vp);
334 			else
335 				ret |= ktrops(curp, p, ops, facs, vp);
336 
337 	} else {
338 		/*
339 		 * by pid
340 		 */
341 		p = pfind(SCARG(uap, pid));
342 		if (p == NULL) {
343 			error = ESRCH;
344 			goto done;
345 		}
346 		if (descend)
347 			ret |= ktrsetchildren(curp, p, ops, facs, vp);
348 		else
349 			ret |= ktrops(curp, p, ops, facs, vp);
350 	}
351 	if (!ret)
352 		error = EPERM;
353 done:
354 	if (vp != NULL)
355 		(void) vn_close(vp, FWRITE, curp->p_ucred, curp);
356 	curp->p_traceflag &= ~KTRFAC_ACTIVE;
357 	return (error);
358 }
359 
360 int
361 ktrops(curp, p, ops, facs, vp)
362 	struct proc *p, *curp;
363 	int ops, facs;
364 	struct vnode *vp;
365 {
366 
367 	if (!ktrcanset(curp, p))
368 		return (0);
369 	if (ops == KTROP_SET) {
370 		if (p->p_tracep != vp) {
371 			/*
372 			 * if trace file already in use, relinquish
373 			 */
374 			if (p->p_tracep != NULL)
375 				vrele(p->p_tracep);
376 			VREF(vp);
377 			p->p_tracep = vp;
378 		}
379 		p->p_traceflag |= facs;
380 		if (curp->p_ucred->cr_uid == 0)
381 			p->p_traceflag |= KTRFAC_ROOT;
382 	} else {
383 		/* KTROP_CLEAR */
384 		if (((p->p_traceflag &= ~facs) & KTRFAC_MASK) == 0) {
385 			/* no more tracing */
386 			p->p_traceflag = 0;
387 			if (p->p_tracep != NULL) {
388 				vrele(p->p_tracep);
389 				p->p_tracep = NULL;
390 			}
391 		}
392 	}
393 
394 	return (1);
395 }
396 
397 ktrsetchildren(curp, top, ops, facs, vp)
398 	struct proc *curp, *top;
399 	int ops, facs;
400 	struct vnode *vp;
401 {
402 	register struct proc *p;
403 	register int ret = 0;
404 
405 	p = top;
406 	for (;;) {
407 		ret |= ktrops(curp, p, ops, facs, vp);
408 		/*
409 		 * If this process has children, descend to them next,
410 		 * otherwise do any siblings, and if done with this level,
411 		 * follow back up the tree (but not past top).
412 		 */
413 		if (p->p_children.lh_first)
414 			p = p->p_children.lh_first;
415 		else for (;;) {
416 			if (p == top)
417 				return (ret);
418 			if (p->p_sibling.le_next) {
419 				p = p->p_sibling.le_next;
420 				break;
421 			}
422 			p = p->p_pptr;
423 		}
424 	}
425 	/*NOTREACHED*/
426 }
427 
428 ktrwrite(vp, kth)
429 	struct vnode *vp;
430 	register struct ktr_header *kth;
431 {
432 	struct uio auio;
433 	struct iovec aiov[2];
434 	register struct proc *p = curproc;	/* XXX */
435 	int error;
436 
437 	if (vp == NULL)
438 		return;
439 	auio.uio_iov = &aiov[0];
440 	auio.uio_offset = 0;
441 	auio.uio_segflg = UIO_SYSSPACE;
442 	auio.uio_rw = UIO_WRITE;
443 	aiov[0].iov_base = (caddr_t)kth;
444 	aiov[0].iov_len = sizeof(struct ktr_header);
445 	auio.uio_resid = sizeof(struct ktr_header);
446 	auio.uio_iovcnt = 1;
447 	auio.uio_procp = (struct proc *)0;
448 	if (kth->ktr_len > 0) {
449 		auio.uio_iovcnt++;
450 		aiov[1].iov_base = kth->ktr_buf;
451 		aiov[1].iov_len = kth->ktr_len;
452 		auio.uio_resid += kth->ktr_len;
453 	}
454 	VOP_LOCK(vp);
455 	error = VOP_WRITE(vp, &auio, IO_UNIT|IO_APPEND, p->p_ucred);
456 	VOP_UNLOCK(vp);
457 	if (!error)
458 		return;
459 	/*
460 	 * If error encountered, give up tracing on this vnode.
461 	 */
462 	log(LOG_NOTICE, "ktrace write failed, errno %d, tracing stopped\n",
463 	    error);
464 	for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) {
465 		if (p->p_tracep == vp) {
466 			p->p_tracep = NULL;
467 			p->p_traceflag = 0;
468 			vrele(vp);
469 		}
470 	}
471 }
472 
473 /*
474  * Return true if caller has permission to set the ktracing state
475  * of target.  Essentially, the target can't possess any
476  * more permissions than the caller.  KTRFAC_ROOT signifies that
477  * root previously set the tracing status on the target process, and
478  * so, only root may further change it.
479  *
480  * TODO: check groups.  use caller effective gid.
481  */
482 ktrcanset(callp, targetp)
483 	struct proc *callp, *targetp;
484 {
485 	register struct pcred *caller = callp->p_cred;
486 	register struct pcred *target = targetp->p_cred;
487 
488 	if ((caller->pc_ucred->cr_uid == target->p_ruid &&
489 	     target->p_ruid == target->p_svuid &&
490 	     caller->p_rgid == target->p_rgid &&	/* XXX */
491 	     target->p_rgid == target->p_svgid &&
492 	     (targetp->p_traceflag & KTRFAC_ROOT) == 0) ||
493 	     caller->pc_ucred->cr_uid == 0)
494 		return (1);
495 
496 	return (0);
497 }
498 
499 #endif
500