xref: /freebsd/sys/kern/kern_ktrace.c (revision 17ee9d00bc1ae1e598c38f25826f861e4bc6c3ce) 
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. All advertising materials mentioning features or use of this software
14  *    must display the following acknowledgement:
15  *	This product includes software developed by the University of
16  *	California, Berkeley and its contributors.
17  * 4. Neither the name of the University nor the names of its contributors
18  *    may be used to endorse or promote products derived from this software
19  *    without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  *
33  *	@(#)kern_ktrace.c	8.2 (Berkeley) 9/23/93
34  * $Id: kern_ktrace.c,v 1.4 1994/08/18 22:35:01 wollman Exp $
35  */
36 
37 #ifdef KTRACE
38 
39 #include <sys/param.h>
40 #include <sys/systm.h>
41 #include <sys/proc.h>
42 #include <sys/file.h>
43 #include <sys/namei.h>
44 #include <sys/vnode.h>
45 #include <sys/ktrace.h>
46 #include <sys/malloc.h>
47 #include <sys/syslog.h>
48 
49 struct ktr_header *
50 ktrgetheader(type)
51 	int type;
52 {
53 	register struct ktr_header *kth;
54 	struct proc *p = curproc;	/* XXX */
55 
56 	MALLOC(kth, struct ktr_header *, sizeof (struct ktr_header),
57 		M_TEMP, M_WAITOK);
58 	kth->ktr_type = type;
59 	microtime(&kth->ktr_time);
60 	kth->ktr_pid = p->p_pid;
61 	bcopy(p->p_comm, kth->ktr_comm, MAXCOMLEN);
62 	return (kth);
63 }
64 
65 void
66 ktrsyscall(vp, code, narg, args)
67 	struct vnode *vp;
68 	int code, narg, args[];
69 {
70 	struct	ktr_header *kth;
71 	struct	ktr_syscall *ktp;
72 	register len = sizeof(struct ktr_syscall) + (narg * sizeof(int));
73 	struct proc *p = curproc;	/* XXX */
74 	int 	*argp, i;
75 
76 	p->p_traceflag |= KTRFAC_ACTIVE;
77 	kth = ktrgetheader(KTR_SYSCALL);
78 	MALLOC(ktp, struct ktr_syscall *, len, M_TEMP, M_WAITOK);
79 	ktp->ktr_code = code;
80 	ktp->ktr_narg = narg;
81 	argp = (int *)((char *)ktp + sizeof(struct ktr_syscall));
82 	for (i = 0; i < narg; i++)
83 		*argp++ = args[i];
84 	kth->ktr_buf = (caddr_t)ktp;
85 	kth->ktr_len = len;
86 	ktrwrite(vp, kth);
87 	FREE(ktp, M_TEMP);
88 	FREE(kth, M_TEMP);
89 	p->p_traceflag &= ~KTRFAC_ACTIVE;
90 }
91 
92 void
93 ktrsysret(vp, code, error, retval)
94 	struct vnode *vp;
95 	int code, error, retval;
96 {
97 	struct ktr_header *kth;
98 	struct ktr_sysret ktp;
99 	struct proc *p = curproc;	/* XXX */
100 
101 	p->p_traceflag |= KTRFAC_ACTIVE;
102 	kth = ktrgetheader(KTR_SYSRET);
103 	ktp.ktr_code = code;
104 	ktp.ktr_error = error;
105 	ktp.ktr_retval = retval;		/* what about val2 ? */
106 
107 	kth->ktr_buf = (caddr_t)&ktp;
108 	kth->ktr_len = sizeof(struct ktr_sysret);
109 
110 	ktrwrite(vp, kth);
111 	FREE(kth, M_TEMP);
112 	p->p_traceflag &= ~KTRFAC_ACTIVE;
113 }
114 
115 void
116 ktrnamei(vp, path)
117 	struct vnode *vp;
118 	char *path;
119 {
120 	struct ktr_header *kth;
121 	struct proc *p = curproc;	/* XXX */
122 
123 	p->p_traceflag |= KTRFAC_ACTIVE;
124 	kth = ktrgetheader(KTR_NAMEI);
125 	kth->ktr_len = strlen(path);
126 	kth->ktr_buf = path;
127 
128 	ktrwrite(vp, kth);
129 	FREE(kth, M_TEMP);
130 	p->p_traceflag &= ~KTRFAC_ACTIVE;
131 }
132 
133 void
134 ktrgenio(vp, fd, rw, iov, len, error)
135 	struct vnode *vp;
136 	int fd;
137 	enum uio_rw rw;
138 	register struct iovec *iov;
139 	int len, error;
140 {
141 	struct ktr_header *kth;
142 	register struct ktr_genio *ktp;
143 	register caddr_t cp;
144 	register int resid = len, cnt;
145 	struct proc *p = curproc;	/* XXX */
146 
147 	if (error)
148 		return;
149 	p->p_traceflag |= KTRFAC_ACTIVE;
150 	kth = ktrgetheader(KTR_GENIO);
151 	MALLOC(ktp, struct ktr_genio *, sizeof(struct ktr_genio) + len,
152 		M_TEMP, M_WAITOK);
153 	ktp->ktr_fd = fd;
154 	ktp->ktr_rw = rw;
155 	cp = (caddr_t)((char *)ktp + sizeof (struct ktr_genio));
156 	while (resid > 0) {
157 		if ((cnt = iov->iov_len) > resid)
158 			cnt = resid;
159 		if (copyin(iov->iov_base, cp, (unsigned)cnt))
160 			goto done;
161 		cp += cnt;
162 		resid -= cnt;
163 		iov++;
164 	}
165 	kth->ktr_buf = (caddr_t)ktp;
166 	kth->ktr_len = sizeof (struct ktr_genio) + len;
167 
168 	ktrwrite(vp, kth);
169 done:
170 	FREE(kth, M_TEMP);
171 	FREE(ktp, M_TEMP);
172 	p->p_traceflag &= ~KTRFAC_ACTIVE;
173 }
174 
175 void
176 ktrpsig(vp, sig, action, mask, code)
177 	struct vnode *vp;
178 	int sig;
179 	sig_t action;
180 	int mask, code;
181 {
182 	struct ktr_header *kth;
183 	struct ktr_psig	kp;
184 	struct proc *p = curproc;	/* XXX */
185 
186 	p->p_traceflag |= KTRFAC_ACTIVE;
187 	kth = ktrgetheader(KTR_PSIG);
188 	kp.signo = (char)sig;
189 	kp.action = action;
190 	kp.mask = mask;
191 	kp.code = code;
192 	kth->ktr_buf = (caddr_t)&kp;
193 	kth->ktr_len = sizeof (struct ktr_psig);
194 
195 	ktrwrite(vp, kth);
196 	FREE(kth, M_TEMP);
197 	p->p_traceflag &= ~KTRFAC_ACTIVE;
198 }
199 
200 void
201 ktrcsw(vp, out, user)
202 	struct vnode *vp;
203 	int out, user;
204 {
205 	struct ktr_header *kth;
206 	struct	ktr_csw kc;
207 	struct proc *p = curproc;	/* XXX */
208 
209 	p->p_traceflag |= KTRFAC_ACTIVE;
210 	kth = ktrgetheader(KTR_CSW);
211 	kc.out = out;
212 	kc.user = user;
213 	kth->ktr_buf = (caddr_t)&kc;
214 	kth->ktr_len = sizeof (struct ktr_csw);
215 
216 	ktrwrite(vp, kth);
217 	FREE(kth, M_TEMP);
218 	p->p_traceflag &= ~KTRFAC_ACTIVE;
219 }
220 
221 /* Interface and common routines */
222 
223 /*
224  * ktrace system call
225  */
226 struct ktrace_args {
227 	char	*fname;
228 	int	ops;
229 	int	facs;
230 	int	pid;
231 };
232 /* ARGSUSED */
233 int
234 ktrace(curp, uap, retval)
235 	struct proc *curp;
236 	register struct ktrace_args *uap;
237 	int *retval;
238 {
239 	register struct vnode *vp = NULL;
240 	register struct proc *p;
241 	struct pgrp *pg;
242 	int facs = uap->facs & ~KTRFAC_ROOT;
243 	int ops = KTROP(uap->ops);
244 	int descend = uap->ops & KTRFLAG_DESCEND;
245 	int ret = 0;
246 	int error = 0;
247 	struct nameidata nd;
248 
249 	curp->p_traceflag |= KTRFAC_ACTIVE;
250 	if (ops != KTROP_CLEAR) {
251 		/*
252 		 * an operation which requires a file argument.
253 		 */
254 		NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, uap->fname, curp);
255 		error = vn_open(&nd, FREAD|FWRITE, 0);
256 		if (error) {
257 			curp->p_traceflag &= ~KTRFAC_ACTIVE;
258 			return (error);
259 		}
260 		vp = nd.ni_vp;
261 		VOP_UNLOCK(vp);
262 		if (vp->v_type != VREG) {
263 			(void) vn_close(vp, FREAD|FWRITE, curp->p_ucred, curp);
264 			curp->p_traceflag &= ~KTRFAC_ACTIVE;
265 			return (EACCES);
266 		}
267 	}
268 	/*
269 	 * Clear all uses of the tracefile
270 	 */
271 	if (ops == KTROP_CLEARFILE) {
272 		for (p = (struct proc *)allproc; p != NULL; p = p->p_next) {
273 			if (p->p_tracep == vp) {
274 				if (ktrcanset(curp, p)) {
275 					p->p_tracep = NULL;
276 					p->p_traceflag = 0;
277 					(void) vn_close(vp, FREAD|FWRITE,
278 						p->p_ucred, p);
279 				} else
280 					error = EPERM;
281 			}
282 		}
283 		goto done;
284 	}
285 	/*
286 	 * need something to (un)trace (XXX - why is this here?)
287 	 */
288 	if (!facs) {
289 		error = EINVAL;
290 		goto done;
291 	}
292 	/*
293 	 * do it
294 	 */
295 	if (uap->pid < 0) {
296 		/*
297 		 * by process group
298 		 */
299 		pg = pgfind(-uap->pid);
300 		if (pg == NULL) {
301 			error = ESRCH;
302 			goto done;
303 		}
304 		for (p = pg->pg_mem; p != NULL; p = p->p_pgrpnxt)
305 			if (descend)
306 				ret |= ktrsetchildren(curp, p, ops, facs, vp);
307 			else
308 				ret |= ktrops(curp, p, ops, facs, vp);
309 
310 	} else {
311 		/*
312 		 * by pid
313 		 */
314 		p = pfind(uap->pid);
315 		if (p == NULL) {
316 			error = ESRCH;
317 			goto done;
318 		}
319 		if (descend)
320 			ret |= ktrsetchildren(curp, p, ops, facs, vp);
321 		else
322 			ret |= ktrops(curp, p, ops, facs, vp);
323 	}
324 	if (!ret)
325 		error = EPERM;
326 done:
327 	if (vp != NULL)
328 		(void) vn_close(vp, FWRITE, curp->p_ucred, curp);
329 	curp->p_traceflag &= ~KTRFAC_ACTIVE;
330 	return (error);
331 }
332 
333 int
334 ktrops(curp, p, ops, facs, vp)
335 	struct proc *p, *curp;
336 	int ops, facs;
337 	struct vnode *vp;
338 {
339 
340 	if (!ktrcanset(curp, p))
341 		return (0);
342 	if (ops == KTROP_SET) {
343 		if (p->p_tracep != vp) {
344 			/*
345 			 * if trace file already in use, relinquish
346 			 */
347 			if (p->p_tracep != NULL)
348 				vrele(p->p_tracep);
349 			VREF(vp);
350 			p->p_tracep = vp;
351 		}
352 		p->p_traceflag |= facs;
353 		if (curp->p_ucred->cr_uid == 0)
354 			p->p_traceflag |= KTRFAC_ROOT;
355 	} else {
356 		/* KTROP_CLEAR */
357 		if (((p->p_traceflag &= ~facs) & KTRFAC_MASK) == 0) {
358 			/* no more tracing */
359 			p->p_traceflag = 0;
360 			if (p->p_tracep != NULL) {
361 				vrele(p->p_tracep);
362 				p->p_tracep = NULL;
363 			}
364 		}
365 	}
366 
367 	return (1);
368 }
369 
370 int
371 ktrsetchildren(curp, top, ops, facs, vp)
372 	struct proc *curp, *top;
373 	int ops, facs;
374 	struct vnode *vp;
375 {
376 	register struct proc *p;
377 	register int ret = 0;
378 
379 	p = top;
380 	for (;;) {
381 		ret |= ktrops(curp, p, ops, facs, vp);
382 		/*
383 		 * If this process has children, descend to them next,
384 		 * otherwise do any siblings, and if done with this level,
385 		 * follow back up the tree (but not past top).
386 		 */
387 		if (p->p_cptr)
388 			p = p->p_cptr;
389 		else if (p == top)
390 			return (ret);
391 		else if (p->p_osptr)
392 			p = p->p_osptr;
393 		else for (;;) {
394 			p = p->p_pptr;
395 			if (p == top)
396 				return (ret);
397 			if (p->p_osptr) {
398 				p = p->p_osptr;
399 				break;
400 			}
401 		}
402 	}
403 	/*NOTREACHED*/
404 }
405 
406 void
407 ktrwrite(vp, kth)
408 	struct vnode *vp;
409 	register struct ktr_header *kth;
410 {
411 	struct uio auio;
412 	struct iovec aiov[2];
413 	register struct proc *p = curproc;	/* XXX */
414 	int error;
415 
416 	if (vp == NULL)
417 		return;
418 	auio.uio_iov = &aiov[0];
419 	auio.uio_offset = 0;
420 	auio.uio_segflg = UIO_SYSSPACE;
421 	auio.uio_rw = UIO_WRITE;
422 	aiov[0].iov_base = (caddr_t)kth;
423 	aiov[0].iov_len = sizeof(struct ktr_header);
424 	auio.uio_resid = sizeof(struct ktr_header);
425 	auio.uio_iovcnt = 1;
426 	auio.uio_procp = (struct proc *)0;
427 	if (kth->ktr_len > 0) {
428 		auio.uio_iovcnt++;
429 		aiov[1].iov_base = kth->ktr_buf;
430 		aiov[1].iov_len = kth->ktr_len;
431 		auio.uio_resid += kth->ktr_len;
432 	}
433 	VOP_LOCK(vp);
434 	error = VOP_WRITE(vp, &auio, IO_UNIT|IO_APPEND, p->p_ucred);
435 	VOP_UNLOCK(vp);
436 	if (!error)
437 		return;
438 	/*
439 	 * If error encountered, give up tracing on this vnode.
440 	 */
441 	log(LOG_NOTICE, "ktrace write failed, errno %d, tracing stopped\n",
442 	    error);
443 	for (p = (struct proc *)allproc; p != NULL; p = p->p_next) {
444 		if (p->p_tracep == vp) {
445 			p->p_tracep = NULL;
446 			p->p_traceflag = 0;
447 			vrele(vp);
448 		}
449 	}
450 }
451 
452 /*
453  * Return true if caller has permission to set the ktracing state
454  * of target.  Essentially, the target can't possess any
455  * more permissions than the caller.  KTRFAC_ROOT signifies that
456  * root previously set the tracing status on the target process, and
457  * so, only root may further change it.
458  *
459  * TODO: check groups.  use caller effective gid.
460  */
461 int
462 ktrcanset(callp, targetp)
463 	struct proc *callp, *targetp;
464 {
465 	register struct pcred *caller = callp->p_cred;
466 	register struct pcred *target = targetp->p_cred;
467 
468 	if ((caller->pc_ucred->cr_uid == target->p_ruid &&
469 	     target->p_ruid == target->p_svuid &&
470 	     caller->p_rgid == target->p_rgid &&	/* XXX */
471 	     target->p_rgid == target->p_svgid &&
472 	     (targetp->p_traceflag & KTRFAC_ROOT) == 0) ||
473 	     caller->pc_ucred->cr_uid == 0)
474 		return (1);
475 
476 	return (0);
477 }
478 
479 #endif
480