Home | History | Annotate | Line # | Download | only in kern
kern_ktrace.c revision 1.33.6.2 
      1 /*	$NetBSD: kern_ktrace.c,v 1.33.6.2 2000/04/30 20:13:33 he 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	8.5 (Berkeley) 5/14/95
     36  */
     37 
     38 #include "opt_ktrace.h"
     39 
     40 #ifdef KTRACE
     41 
     42 #include <sys/param.h>
     43 #include <sys/systm.h>
     44 #include <sys/proc.h>
     45 #include <sys/file.h>
     46 #include <sys/namei.h>
     47 #include <sys/vnode.h>
     48 #include <sys/ktrace.h>
     49 #include <sys/malloc.h>
     50 #include <sys/syslog.h>
     51 #include <sys/filedesc.h>
     52 
     53 #include <sys/mount.h>
     54 #include <sys/syscallargs.h>
     55 
     56 #include <vm/vm.h>		/* XXX for uvmexp, needed by PAGE_SIZE */
     57 #include <uvm/uvm.h>		/* XXX for uvmexp, needed by PAGE_SIZE */
     58 
     59 void	ktrinitheader __P((struct ktr_header *, struct proc *, int));
     60 int	ktrops __P((struct proc *, struct proc *, int, int, void *));
     61 int	ktrsetchildren __P((struct proc *, struct proc *, int, int, void *));
     62 int	ktrwrite __P((struct proc *, void *, struct ktr_header *));
     63 int	ktrcanset __P((struct proc *, struct proc *));
     64 
     65 void
     66 ktrderef(p)
     67 	struct proc *p;
     68 {
     69 	if (p->p_tracep == NULL)
     70 		return;
     71 
     72 	if (p->p_traceflag & KTRFAC_FD) {
     73 		struct file *fp = p->p_tracep;
     74 
     75 		closef(fp, NULL);
     76 	} else {
     77 		struct vnode *vp = p->p_tracep;
     78 
     79 		vrele(vp);
     80 	}
     81 	p->p_tracep = NULL;
     82 	p->p_traceflag = 0;
     83 }
     84 
     85 void
     86 ktradref(p)
     87 	struct proc *p;
     88 {
     89 	if (p->p_traceflag & KTRFAC_FD) {
     90 		struct file *fp = p->p_tracep;
     91 
     92 		fp->f_count++;
     93 	} else {
     94 		struct vnode *vp = p->p_tracep;
     95 
     96 		VREF(vp);
     97 	}
     98 }
     99 
    100 void
    101 ktrinitheader(kth, p, type)
    102 	struct ktr_header *kth;
    103 	struct proc *p;
    104 	int type;
    105 {
    106 
    107 	memset(kth, 0, sizeof(*kth));
    108 	kth->ktr_type = type;
    109 	microtime(&kth->ktr_time);
    110 	kth->ktr_pid = p->p_pid;
    111 	memcpy(kth->ktr_comm, p->p_comm, MAXCOMLEN);
    112 }
    113 
    114 void
    115 ktrsyscall(v, code, argsize, args)
    116 	void *v;
    117 	register_t code;
    118 	size_t argsize;
    119 	register_t args[];
    120 {
    121 	struct ktr_header kth;
    122 	struct ktr_syscall *ktp;
    123 	struct proc *p = curproc;	/* XXX */
    124 	register_t *argp;
    125 	size_t len = sizeof(struct ktr_syscall) + argsize;
    126 	int i;
    127 
    128 	p->p_traceflag |= KTRFAC_ACTIVE;
    129 	ktrinitheader(&kth, p, KTR_SYSCALL);
    130 	ktp = malloc(len, M_TEMP, M_WAITOK);
    131 	ktp->ktr_code = code;
    132 	ktp->ktr_argsize = argsize;
    133 	argp = (register_t *)((char *)ktp + sizeof(struct ktr_syscall));
    134 	for (i = 0; i < (argsize / sizeof(*argp)); i++)
    135 		*argp++ = args[i];
    136 	kth.ktr_buf = (caddr_t)ktp;
    137 	kth.ktr_len = len;
    138 	(void) ktrwrite(p, v, &kth);
    139 	free(ktp, M_TEMP);
    140 	p->p_traceflag &= ~KTRFAC_ACTIVE;
    141 }
    142 
    143 void
    144 ktrsysret(v, code, error, retval)
    145 	void *v;
    146 	register_t code;
    147 	int error;
    148 	register_t retval;
    149 {
    150 	struct ktr_header kth;
    151 	struct ktr_sysret ktp;
    152 	struct proc *p = curproc;	/* XXX */
    153 
    154 	p->p_traceflag |= KTRFAC_ACTIVE;
    155 	ktrinitheader(&kth, p, KTR_SYSRET);
    156 	ktp.ktr_code = code;
    157 	ktp.ktr_error = error;
    158 	ktp.ktr_retval = retval;		/* what about val2 ? */
    159 
    160 	kth.ktr_buf = (caddr_t)&ktp;
    161 	kth.ktr_len = sizeof(struct ktr_sysret);
    162 
    163 	(void) ktrwrite(p, v, &kth);
    164 	p->p_traceflag &= ~KTRFAC_ACTIVE;
    165 }
    166 
    167 void
    168 ktrnamei(v, path)
    169 	void *v;
    170 	char *path;
    171 {
    172 	struct ktr_header kth;
    173 	struct proc *p = curproc;	/* XXX */
    174 
    175 	p->p_traceflag |= KTRFAC_ACTIVE;
    176 	ktrinitheader(&kth, p, KTR_NAMEI);
    177 	kth.ktr_len = strlen(path);
    178 	kth.ktr_buf = path;
    179 
    180 	(void) ktrwrite(p, v, &kth);
    181 	p->p_traceflag &= ~KTRFAC_ACTIVE;
    182 }
    183 
    184 void
    185 ktremul(v, p, emul)
    186 	void *v;
    187 	struct proc *p;
    188 	char *emul;
    189 {
    190 	struct ktr_header kth;
    191 
    192 	p->p_traceflag |= KTRFAC_ACTIVE;
    193 	ktrinitheader(&kth, p, KTR_EMUL);
    194 	kth.ktr_len = strlen(emul);
    195 	kth.ktr_buf = emul;
    196 
    197 	(void) ktrwrite(p, v, &kth);
    198 	p->p_traceflag &= ~KTRFAC_ACTIVE;
    199 }
    200 
    201 void
    202 ktrgenio(v, fd, rw, iov, len, error)
    203 	void *v;
    204 	int fd;
    205 	enum uio_rw rw;
    206 	struct iovec *iov;
    207 	int len, error;
    208 {
    209 	struct ktr_header kth;
    210 	struct ktr_genio *ktp;
    211 	caddr_t cp;
    212 	int resid = len, cnt;
    213 	struct proc *p = curproc;	/* XXX */
    214 	int buflen;
    215 
    216 	if (error)
    217 		return;
    218 
    219 	p->p_traceflag |= KTRFAC_ACTIVE;
    220 
    221 	buflen = min(PAGE_SIZE, len + sizeof(struct ktr_genio));
    222 
    223 	ktrinitheader(&kth, p, KTR_GENIO);
    224 	ktp = malloc(buflen, M_TEMP, M_WAITOK);
    225 	ktp->ktr_fd = fd;
    226 	ktp->ktr_rw = rw;
    227 
    228 	kth.ktr_buf = (caddr_t)ktp;
    229 
    230 	cp = (caddr_t)((char *)ktp + sizeof(struct ktr_genio));
    231 	buflen -= sizeof(struct ktr_genio);
    232 
    233 	while (resid > 0) {
    234 		if (schedflags & PSCHED_SHOULDYIELD)
    235 			preempt(NULL);
    236 
    237 		cnt = min(iov->iov_len, buflen);
    238 		if (cnt > resid)
    239 			cnt = resid;
    240 		if (copyin(iov->iov_base, cp, cnt))
    241 			break;
    242 
    243 		kth.ktr_len = cnt + sizeof(struct ktr_genio);
    244 
    245 		if (ktrwrite(p, v, &kth) != 0)
    246 			break;
    247 
    248 		iov->iov_base = (caddr_t)iov->iov_base + cnt;
    249 		iov->iov_len -= cnt;
    250 
    251 		if (iov->iov_len == 0)
    252 			iov++;
    253 
    254 		resid -= cnt;
    255 	}
    256 
    257 	free(ktp, M_TEMP);
    258 	p->p_traceflag &= ~KTRFAC_ACTIVE;
    259 }
    260 
    261 void
    262 ktrpsig(v, sig, action, mask, code)
    263 	void *v;
    264 	int sig;
    265 	sig_t action;
    266 	sigset_t *mask;
    267 	int code;
    268 {
    269 	struct ktr_header kth;
    270 	struct ktr_psig	kp;
    271 	struct proc *p = curproc;	/* XXX */
    272 
    273 	p->p_traceflag |= KTRFAC_ACTIVE;
    274 	ktrinitheader(&kth, p, KTR_PSIG);
    275 	kp.signo = (char)sig;
    276 	kp.action = action;
    277 	kp.mask = *mask;
    278 	kp.code = code;
    279 	kth.ktr_buf = (caddr_t)&kp;
    280 	kth.ktr_len = sizeof(struct ktr_psig);
    281 
    282 	(void) ktrwrite(p, v, &kth);
    283 	p->p_traceflag &= ~KTRFAC_ACTIVE;
    284 }
    285 
    286 void
    287 ktrcsw(v, out, user)
    288 	void *v;
    289 	int out, user;
    290 {
    291 	struct ktr_header kth;
    292 	struct ktr_csw kc;
    293 	struct proc *p = curproc;	/* XXX */
    294 
    295 	p->p_traceflag |= KTRFAC_ACTIVE;
    296 	ktrinitheader(&kth, p, KTR_CSW);
    297 	kc.out = out;
    298 	kc.user = user;
    299 	kth.ktr_buf = (caddr_t)&kc;
    300 	kth.ktr_len = sizeof(struct ktr_csw);
    301 
    302 	(void) ktrwrite(p, v, &kth);
    303 	p->p_traceflag &= ~KTRFAC_ACTIVE;
    304 }
    305 
    306 /* Interface and common routines */
    307 
    308 /*
    309  * ktrace system call
    310  */
    311 /* ARGSUSED */
    312 int
    313 sys_fktrace(curp, v, retval)
    314 	struct proc *curp;
    315 	void *v;
    316 	register_t *retval;
    317 {
    318 	struct sys_fktrace_args /* {
    319 		syscallarg(int) fd;
    320 		syscallarg(int) ops;
    321 		syscallarg(int) facs;
    322 		syscallarg(int) pid;
    323 	} */ *uap = v;
    324 	struct file *fp = NULL;
    325 	struct proc *p;
    326 	struct filedesc *fdp = curp->p_fd;
    327 	struct pgrp *pg;
    328 	int facs;
    329 	int ops;
    330 	int descend;
    331 	int ret = 0;
    332 	int error = 0;
    333 
    334 	if (((u_int)SCARG(uap, fd)) >= fdp->fd_nfiles ||
    335 	    (fp = fdp->fd_ofiles[SCARG(uap, fd)]) == NULL ||
    336 	    (fp->f_flag & FWRITE) == 0)
    337 		return (EBADF);
    338 
    339 	ops = KTROP(SCARG(uap, ops)) | KTRFLAG_FD;
    340 	descend = SCARG(uap, ops) & KTRFLAG_DESCEND;
    341 	facs = SCARG(uap, facs) & ~((unsigned) KTRFAC_ROOT);
    342 	curp->p_traceflag |= KTRFAC_ACTIVE;
    343 
    344 	/*
    345 	 * Clear all uses of the tracefile
    346 	 */
    347 	if (KTROP(ops) == KTROP_CLEARFILE) {
    348 		for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) {
    349 			if (p->p_tracep == fp) {
    350 				if (ktrcanset(curp, p))
    351 					ktrderef(p);
    352 				else
    353 					error = EPERM;
    354 			}
    355 		}
    356 		goto done;
    357 	}
    358 	/*
    359 	 * need something to (un)trace (XXX - why is this here?)
    360 	 */
    361 	if (!facs) {
    362 		error = EINVAL;
    363 		goto done;
    364 	}
    365 	/*
    366 	 * do it
    367 	 */
    368 	if (SCARG(uap, pid) < 0) {
    369 		/*
    370 		 * by process group
    371 		 */
    372 		pg = pgfind(-SCARG(uap, pid));
    373 		if (pg == NULL) {
    374 			error = ESRCH;
    375 			goto done;
    376 		}
    377 		for (p = LIST_FIRST(&pg->pg_members); p != NULL;
    378 		     p = LIST_NEXT(p, p_pglist)) {
    379 			if (descend)
    380 				ret |= ktrsetchildren(curp, p, ops, facs, fp);
    381 			else
    382 				ret |= ktrops(curp, p, ops, facs, fp);
    383 		}
    384 
    385 	} else {
    386 		/*
    387 		 * by pid
    388 		 */
    389 		p = pfind(SCARG(uap, pid));
    390 		if (p == NULL) {
    391 			error = ESRCH;
    392 			goto done;
    393 		}
    394 		if (descend)
    395 			ret |= ktrsetchildren(curp, p, ops, facs, fp);
    396 		else
    397 			ret |= ktrops(curp, p, ops, facs, fp);
    398 	}
    399 	if (!ret)
    400 		error = EPERM;
    401 done:
    402 	curp->p_traceflag &= ~KTRFAC_ACTIVE;
    403 	return (error);
    404 }
    405 
    406 /*
    407  * ktrace system call
    408  */
    409 /* ARGSUSED */
    410 int
    411 sys_ktrace(curp, v, retval)
    412 	struct proc *curp;
    413 	void *v;
    414 	register_t *retval;
    415 {
    416 	struct sys_ktrace_args /* {
    417 		syscallarg(const char *) fname;
    418 		syscallarg(int) ops;
    419 		syscallarg(int) facs;
    420 		syscallarg(int) pid;
    421 	} */ *uap = v;
    422 	struct vnode *vp = NULL;
    423 	struct proc *p;
    424 	struct pgrp *pg;
    425 	int facs = SCARG(uap, facs) & ~((unsigned) KTRFAC_ROOT);
    426 	int ops = KTROP(SCARG(uap, ops));
    427 	int descend = SCARG(uap, ops) & KTRFLAG_DESCEND;
    428 	int ret = 0;
    429 	int error = 0;
    430 	struct nameidata nd;
    431 
    432 	curp->p_traceflag |= KTRFAC_ACTIVE;
    433 	if (ops != KTROP_CLEAR) {
    434 		/*
    435 		 * an operation which requires a file argument.
    436 		 */
    437 		NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, SCARG(uap, fname),
    438 		    curp);
    439 		if ((error = vn_open(&nd, FREAD|FWRITE, 0)) != 0) {
    440 			curp->p_traceflag &= ~KTRFAC_ACTIVE;
    441 			return (error);
    442 		}
    443 		vp = nd.ni_vp;
    444 		VOP_UNLOCK(vp, 0);
    445 		if (vp->v_type != VREG) {
    446 			(void) vn_close(vp, FREAD|FWRITE, curp->p_ucred, curp);
    447 			curp->p_traceflag &= ~KTRFAC_ACTIVE;
    448 			return (EACCES);
    449 		}
    450 	}
    451 	/*
    452 	 * Clear all uses of the tracefile
    453 	 */
    454 	if (KTROP(ops) == KTROP_CLEARFILE) {
    455 		for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) {
    456 			if (p->p_tracep == vp &&
    457 			    !ktrops(curp, p, KTROP_CLEAR, ~0, vp))
    458 				error = EPERM;
    459 		}
    460 		goto done;
    461 	}
    462 	/*
    463 	 * need something to (un)trace (XXX - why is this here?)
    464 	 */
    465 	if (!facs) {
    466 		error = EINVAL;
    467 		goto done;
    468 	}
    469 	/*
    470 	 * do it
    471 	 */
    472 	if (SCARG(uap, pid) < 0) {
    473 		/*
    474 		 * by process group
    475 		 */
    476 		pg = pgfind(-SCARG(uap, pid));
    477 		if (pg == NULL) {
    478 			error = ESRCH;
    479 			goto done;
    480 		}
    481 		for (p = LIST_FIRST(&pg->pg_members); p != NULL;
    482 		     p = LIST_NEXT(p, p_pglist)) {
    483 			if (descend)
    484 				ret |= ktrsetchildren(curp, p, ops, facs, vp);
    485 			else
    486 				ret |= ktrops(curp, p, ops, facs, vp);
    487 		}
    488 
    489 	} else {
    490 		/*
    491 		 * by pid
    492 		 */
    493 		p = pfind(SCARG(uap, pid));
    494 		if (p == NULL) {
    495 			error = ESRCH;
    496 			goto done;
    497 		}
    498 		if (descend)
    499 			ret |= ktrsetchildren(curp, p, ops, facs, vp);
    500 		else
    501 			ret |= ktrops(curp, p, ops, facs, vp);
    502 	}
    503 	if (!ret)
    504 		error = EPERM;
    505 done:
    506 	if (vp != NULL)
    507 		(void) vn_close(vp, FWRITE, curp->p_ucred, curp);
    508 	curp->p_traceflag &= ~KTRFAC_ACTIVE;
    509 	return (error);
    510 }
    511 
    512 int
    513 ktrops(curp, p, ops, facs, v)
    514 	struct proc *p, *curp;
    515 	int ops, facs;
    516 	void *v;
    517 {
    518 
    519 	if (!ktrcanset(curp, p))
    520 		return (0);
    521 	if (KTROP(ops) == KTROP_SET) {
    522 		if (p->p_tracep != v) {
    523 			/*
    524 			 * if trace file already in use, relinquish
    525 			 */
    526 			ktrderef(p);
    527 			if (ops & KTRFLAG_FD)
    528 				p->p_traceflag = KTRFAC_FD;
    529 			p->p_tracep = v;
    530 			ktradref(p);
    531 		}
    532 		p->p_traceflag |= facs;
    533 		if (curp->p_ucred->cr_uid == 0)
    534 			p->p_traceflag |= KTRFAC_ROOT;
    535 	} else {
    536 		/* KTROP_CLEAR */
    537 		if (((p->p_traceflag &= ~facs) & KTRFAC_MASK) == 0) {
    538 			/* no more tracing */
    539 			ktrderef(p);
    540 		}
    541 	}
    542 
    543 	/*
    544 	 * Emit an emulation record, every time there is a ktrace
    545 	 * change/attach request.
    546 	 */
    547 	if (KTRPOINT(p, KTR_EMUL))
    548 		ktremul(p->p_tracep, p, p->p_emul->e_name);
    549 
    550 	return (1);
    551 }
    552 
    553 int
    554 ktrsetchildren(curp, top, ops, facs, v)
    555 	struct proc *curp, *top;
    556 	int ops, facs;
    557 	void *v;
    558 {
    559 	struct proc *p;
    560 	int ret = 0;
    561 
    562 	p = top;
    563 	for (;;) {
    564 		ret |= ktrops(curp, p, ops, facs, v);
    565 		/*
    566 		 * If this process has children, descend to them next,
    567 		 * otherwise do any siblings, and if done with this level,
    568 		 * follow back up the tree (but not past top).
    569 		 */
    570 		if (LIST_FIRST(&p->p_children) != NULL)
    571 			p = LIST_FIRST(&p->p_children);
    572 		else for (;;) {
    573 			if (p == top)
    574 				return (ret);
    575 			if (LIST_NEXT(p, p_sibling) != NULL) {
    576 				p = LIST_NEXT(p, p_sibling);
    577 				break;
    578 			}
    579 			p = p->p_pptr;
    580 		}
    581 	}
    582 	/*NOTREACHED*/
    583 }
    584 
    585 int
    586 ktrwrite(p, v, kth)
    587 	struct proc *p;
    588 	void *v;
    589 	struct ktr_header *kth;
    590 {
    591 	struct uio auio;
    592 	struct iovec aiov[2];
    593 	int error;
    594 
    595 	if (v == NULL)
    596 		return (0);
    597 	auio.uio_iov = &aiov[0];
    598 	auio.uio_offset = 0;
    599 	auio.uio_segflg = UIO_SYSSPACE;
    600 	auio.uio_rw = UIO_WRITE;
    601 	aiov[0].iov_base = (caddr_t)kth;
    602 	aiov[0].iov_len = sizeof(struct ktr_header);
    603 	auio.uio_resid = sizeof(struct ktr_header);
    604 	auio.uio_iovcnt = 1;
    605 	auio.uio_procp = (struct proc *)0;
    606 	if (kth->ktr_len > 0) {
    607 		auio.uio_iovcnt++;
    608 		aiov[1].iov_base = kth->ktr_buf;
    609 		aiov[1].iov_len = kth->ktr_len;
    610 		auio.uio_resid += kth->ktr_len;
    611 	}
    612 	if (p->p_traceflag & KTRFAC_FD) {
    613 		struct file *fp = v;
    614 
    615 		error = (*fp->f_ops->fo_write)(fp, &fp->f_offset, &auio,
    616 		    fp->f_cred, FOF_UPDATE_OFFSET);
    617 	}
    618 	else {
    619 		struct vnode *vp = v;
    620 
    621 		vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
    622 		error = VOP_WRITE(vp, &auio, IO_UNIT|IO_APPEND, p->p_ucred);
    623 		VOP_UNLOCK(vp, 0);
    624 	}
    625 	if (error == 0)
    626 		return (0);
    627 	/*
    628 	 * If error encountered, give up tracing on this vnode.  Don't report
    629 	 * EPIPE as this can easily happen with fktrace()/ktruss.
    630 	 */
    631 	if (error != EPIPE)
    632 		log(LOG_NOTICE,
    633 		    "ktrace write failed, errno %d, tracing stopped\n",
    634 		    error);
    635 	for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) {
    636 		if (p->p_tracep == v)
    637 			ktrderef(p);
    638 	}
    639 
    640 	return (error);
    641 }
    642 
    643 /*
    644  * Return true if caller has permission to set the ktracing state
    645  * of target.  Essentially, the target can't possess any
    646  * more permissions than the caller.  KTRFAC_ROOT signifies that
    647  * root previously set the tracing status on the target process, and
    648  * so, only root may further change it.
    649  *
    650  * TODO: check groups.  use caller effective gid.
    651  */
    652 int
    653 ktrcanset(callp, targetp)
    654 	struct proc *callp, *targetp;
    655 {
    656 	struct pcred *caller = callp->p_cred;
    657 	struct pcred *target = targetp->p_cred;
    658 
    659 	if ((caller->pc_ucred->cr_uid == target->p_ruid &&
    660 	     target->p_ruid == target->p_svuid &&
    661 	     caller->p_rgid == target->p_rgid &&	/* XXX */
    662 	     target->p_rgid == target->p_svgid &&
    663 	     (targetp->p_traceflag & KTRFAC_ROOT) == 0) ||
    664 	     caller->pc_ucred->cr_uid == 0)
    665 		return (1);
    666 
    667 	return (0);
    668 }
    669 
    670 #endif
    671