[unix-history] / sys / kern / kern_ktrace.c

/*
 * Copyright (c) 1989 The Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)kern_ktrace.c	7.15 (Berkeley) 6/21/91
 */

#ifdef KTRACE

#include "param.h"
#include "proc.h"
#include "file.h"
#include "namei.h"
#include "vnode.h"
#include "ktrace.h"
#include "malloc.h"
#include "syslog.h"

struct ktr_header *
ktrgetheader(type)
{
	register struct ktr_header *kth;
	struct proc *p = curproc;	/* XXX */

	MALLOC(kth, struct ktr_header *, sizeof (struct ktr_header), 
		M_TEMP, M_WAITOK);
	kth->ktr_type = type;
	microtime(&kth->ktr_time);
	kth->ktr_pid = p->p_pid;
	bcopy(p->p_comm, kth->ktr_comm, MAXCOMLEN);
	return (kth);
}

ktrsyscall(vp, code, narg, args)
	struct vnode *vp;
	int code, narg, args[];
{
	struct	ktr_header *kth = ktrgetheader(KTR_SYSCALL);
	struct	ktr_syscall *ktp;
	register len = sizeof(struct ktr_syscall) + (narg * sizeof(int));
	int 	*argp, i;

	MALLOC(ktp, struct ktr_syscall *, len, M_TEMP, M_WAITOK);
	ktp->ktr_code = code;
	ktp->ktr_narg = narg;
	argp = (int *)((char *)ktp + sizeof(struct ktr_syscall));
	for (i = 0; i < narg; i++)
		*argp++ = args[i];
	kth->ktr_buf = (caddr_t)ktp;
	kth->ktr_len = len;
	ktrwrite(vp, kth);
	FREE(ktp, M_TEMP);
	FREE(kth, M_TEMP);
}

ktrsysret(vp, code, error, retval)
	struct vnode *vp;
	int code, error, retval;
{
	struct ktr_header *kth = ktrgetheader(KTR_SYSRET);
	struct ktr_sysret ktp;

	ktp.ktr_code = code;
	ktp.ktr_error = error;
	ktp.ktr_retval = retval;		/* what about val2 ? */

	kth->ktr_buf = (caddr_t)&ktp;
	kth->ktr_len = sizeof(struct ktr_sysret);

	ktrwrite(vp, kth);
	FREE(kth, M_TEMP);
}

ktrnamei(vp, path)
	struct vnode *vp;
	char *path;
{
	struct ktr_header *kth = ktrgetheader(KTR_NAMEI);

	kth->ktr_len = strlen(path);
	kth->ktr_buf = path;

	ktrwrite(vp, kth);
	FREE(kth, M_TEMP);
}

ktrgenio(vp, fd, rw, iov, len, error)
	struct vnode *vp;
	int fd;
	enum uio_rw rw;
	register struct iovec *iov;
{
	struct ktr_header *kth = ktrgetheader(KTR_GENIO);
	register struct ktr_genio *ktp;
	register caddr_t cp;
	register int resid = len, cnt;
	
	if (error)
		return;
	MALLOC(ktp, struct ktr_genio *, sizeof(struct ktr_genio) + len,
		M_TEMP, M_WAITOK);
	ktp->ktr_fd = fd;
	ktp->ktr_rw = rw;
	cp = (caddr_t)((char *)ktp + sizeof (struct ktr_genio));
	while (resid > 0) {
		if ((cnt = iov->iov_len) > resid)
			cnt = resid;
		if (copyin(iov->iov_base, cp, (unsigned)cnt))
			goto done;
		cp += cnt;
		resid -= cnt;
		iov++;
	}
	kth->ktr_buf = (caddr_t)ktp;
	kth->ktr_len = sizeof (struct ktr_genio) + len;

	ktrwrite(vp, kth);
done:
	FREE(kth, M_TEMP);
	FREE(ktp, M_TEMP);
}

ktrpsig(vp, sig, action, mask, code)
	struct	vnode *vp;
	sig_t	action;
{
	struct ktr_header *kth = ktrgetheader(KTR_PSIG);
	struct ktr_psig	kp;

	kp.signo = (char)sig;
	kp.action = action;
	kp.mask = mask;
	kp.code = code;
	kth->ktr_buf = (caddr_t)&kp;
	kth->ktr_len = sizeof (struct ktr_psig);

	ktrwrite(vp, kth);
	FREE(kth, M_TEMP);
}

/* Interface and common routines */

/*
 * ktrace system call
 */

struct ktrace_args {
	char	*fname;
	int	ops;
	int	facs;
	int	pid;
};

/* ARGSUSED */
ktrace(curp, uap, retval)
	struct proc *curp;
	register struct ktrace_args *uap;
	int *retval;
{
	register struct vnode *vp = NULL;
	register struct proc *p;
	struct pgrp *pg;
	int facs = uap->facs & ~KTRFAC_ROOT;
	int ops = KTROP(uap->ops);
	int descend = uap->ops & KTRFLAG_DESCEND;
	int ret = 0;
	int error = 0;
	struct nameidata nd;

	if (ops != KTROP_CLEAR) {
		/*
		 * an operation which requires a file argument.
		 */
		nd.ni_segflg = UIO_USERSPACE;
		nd.ni_dirp = uap->fname;
		if (error = vn_open(&nd, curp, FREAD|FWRITE, 0))
			return (error);
		vp = nd.ni_vp;
		VOP_UNLOCK(vp);
		if (vp->v_type != VREG) {
			(void) vn_close(vp, FREAD|FWRITE, curp->p_ucred, curp);
			return (EACCES);
		}
	}
	/*
	 * Clear all uses of the tracefile
	 */
	if (ops == KTROP_CLEARFILE) {
		for (p = allproc; p != NULL; p = p->p_nxt) {
			if (p->p_tracep == vp) {
				if (ktrcanset(curp, p)) {
					p->p_tracep = NULL;
					p->p_traceflag = 0;
					(void) vn_close(vp, FREAD|FWRITE,
						p->p_ucred, p);
				} else
					error = EPERM;
			}
		}
		goto done;
	}
	/*
	 * need something to (un)trace (XXX - why is this here?)
	 */
	if (!facs) {
		error = EINVAL;
		goto done;
	}
	/* 
	 * do it
	 */
	if (uap->pid < 0) {
		/*
		 * by process group
		 */
		pg = pgfind(-uap->pid);
		if (pg == NULL) {
			error = ESRCH;
			goto done;
		}
		for (p = pg->pg_mem; p != NULL; p = p->p_pgrpnxt)
			if (descend)
				ret |= ktrsetchildren(curp, p, ops, facs, vp);
			else 
				ret |= ktrops(curp, p, ops, facs, vp);
					
	} else {
		/*
		 * by pid
		 */
		p = pfind(uap->pid);
		if (p == NULL) {
			error = ESRCH;
			goto done;
		}
		if (descend)
			ret |= ktrsetchildren(curp, p, ops, facs, vp);
		else
			ret |= ktrops(curp, p, ops, facs, vp);
	}
	if (!ret)
		error = EPERM;
done:
	if (vp != NULL)
		(void) vn_close(vp, FWRITE, curp->p_ucred, curp);
	return (error);
}

ktrops(curp, p, ops, facs, vp)
	struct proc *curp, *p;
	struct vnode *vp;
{

	if (!ktrcanset(curp, p))
		return (0);
	if (ops == KTROP_SET) {
		if (p->p_tracep != vp) { 
			/*
			 * if trace file already in use, relinquish
			 */
			if (p->p_tracep != NULL)
				vrele(p->p_tracep);
			VREF(vp);
			p->p_tracep = vp;
		}
		p->p_traceflag |= facs;
		if (curp->p_ucred->cr_uid == 0)
			p->p_traceflag |= KTRFAC_ROOT;
	} else {	
		/* KTROP_CLEAR */
		if (((p->p_traceflag &= ~facs) & KTRFAC_MASK) == 0) {
			/* no more tracing */
			p->p_traceflag = 0;
			if (p->p_tracep != NULL) {
				vrele(p->p_tracep);
				p->p_tracep = NULL;
			}
		}
	}

	return (1);
}

ktrsetchildren(curp, top, ops, facs, vp)
	struct proc *curp, *top;
	struct vnode *vp;
{
	register struct proc *p;
	register int ret = 0;

	p = top;
	for (;;) {
		ret |= ktrops(curp, p, ops, facs, vp);
		/*
		 * If this process has children, descend to them next,
		 * otherwise do any siblings, and if done with this level,
		 * follow back up the tree (but not past top).
		 */
		if (p->p_cptr)
			p = p->p_cptr;
		else if (p == top)
			return (ret);
		else if (p->p_osptr)
			p = p->p_osptr;
		else for (;;) {
			p = p->p_pptr;
			if (p == top)
				return (ret);
			if (p->p_osptr) {
				p = p->p_osptr;
				break;
			}
		}
	}
	/*NOTREACHED*/
}

ktrwrite(vp, kth)
	struct vnode *vp;
	register struct ktr_header *kth;
{
	struct uio auio;
	struct iovec aiov[2];
	register struct proc *p = curproc;	/* XXX */
	int error;

	if (vp == NULL)
		return;
	auio.uio_iov = &aiov[0];
	auio.uio_offset = 0;
	auio.uio_segflg = UIO_SYSSPACE;
	auio.uio_rw = UIO_WRITE;
	aiov[0].iov_base = (caddr_t)kth;
	aiov[0].iov_len = sizeof(struct ktr_header);
	auio.uio_resid = sizeof(struct ktr_header);
	auio.uio_iovcnt = 1;
	auio.uio_procp = (struct proc *)0;
	if (kth->ktr_len > 0) {
		auio.uio_iovcnt++;
		aiov[1].iov_base = kth->ktr_buf;
		aiov[1].iov_len = kth->ktr_len;
		auio.uio_resid += kth->ktr_len;
	}
	VOP_LOCK(vp);
	error = VOP_WRITE(vp, &auio, IO_UNIT|IO_APPEND, p->p_ucred);
	VOP_UNLOCK(vp);
	if (!error)
		return;
	/*
	 * If error encountered, give up tracing on this vnode.
	 */
	log(LOG_NOTICE, "ktrace write failed, errno %d, tracing stopped\n",
	    error);
	for (p = allproc; p != NULL; p = p->p_nxt) {
		if (p->p_tracep == vp) {
			p->p_tracep = NULL;
			p->p_traceflag = 0;
			vrele(vp);
		}
	}
}

/*
 * Return true if caller has permission to set the ktracing state
 * of target.  Essentially, the target can't possess any
 * more permissions than the caller.  KTRFAC_ROOT signifies that
 * root previously set the tracing status on the target process, and 
 * so, only root may further change it.
 *
 * TODO: check groups.  use caller effective gid.
 */
ktrcanset(callp, targetp)
	struct proc *callp, *targetp;
{
	register struct pcred *caller = callp->p_cred;
	register struct pcred *target = targetp->p_cred;

	if ((caller->pc_ucred->cr_uid == target->p_ruid &&
	     target->p_ruid == target->p_svuid &&
	     caller->p_rgid == target->p_rgid &&	/* XXX */
	     target->p_rgid == target->p_svgid &&
	     (targetp->p_traceflag & KTRFAC_ROOT) == 0) ||
	     caller->pc_ucred->cr_uid == 0)
		return (1);

	return (0);
}

#endif
Commit	Line	Data
15637ed4 RG	1	/*
	2	* Copyright (c) 1989 The Regents of the University of California.
	3	* 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 7.15 (Berkeley) 6/21/91
	34	*/
	35
	36	#ifdef KTRACE
	37
	38	#include "param.h"
	39	#include "proc.h"
	40	#include "file.h"
	41	#include "namei.h"
	42	#include "vnode.h"
	43	#include "ktrace.h"
	44	#include "malloc.h"
	45	#include "syslog.h"
	46
	47	struct ktr_header *
	48	ktrgetheader(type)
	49	{
	50	register struct ktr_header *kth;
	51	struct proc p = curproc; / XXX */
	52
	53	MALLOC(kth, struct ktr_header *, sizeof (struct ktr_header),
	54	M_TEMP, M_WAITOK);
	55	kth->ktr_type = type;
	56	microtime(&kth->ktr_time);
	57	kth->ktr_pid = p->p_pid;
	58	bcopy(p->p_comm, kth->ktr_comm, MAXCOMLEN);
	59	return (kth);
	60	}
	61
	62	ktrsyscall(vp, code, narg, args)
	63	struct vnode *vp;
	64	int code, narg, args[];
65	{
66	struct ktr_header *kth = ktrgetheader(KTR_SYSCALL);
67	struct ktr_syscall *ktp;
68	register len = sizeof(struct ktr_syscall) + (narg * sizeof(int));
69	int *argp, i;
70
71	MALLOC(ktp, struct ktr_syscall *, len, M_TEMP, M_WAITOK);
72	ktp->ktr_code = code;
73	ktp->ktr_narg = narg;
74	argp = (int )((char )ktp + sizeof(struct ktr_syscall));
75	for (i = 0; i < narg; i++)
76	*argp++ = args[i];
77	kth->ktr_buf = (caddr_t)ktp;
78	kth->ktr_len = len;
79	ktrwrite(vp, kth);
80	FREE(ktp, M_TEMP);
81	FREE(kth, M_TEMP);
82	}
83
84	ktrsysret(vp, code, error, retval)
85	struct vnode *vp;
86	int code, error, retval;
87	{
88	struct ktr_header *kth = ktrgetheader(KTR_SYSRET);
89	struct ktr_sysret ktp;
90
91	ktp.ktr_code = code;
92	ktp.ktr_error = error;
93	ktp.ktr_retval = retval; /* what about val2 ? */
94
95	kth->ktr_buf = (caddr_t)&ktp;
96	kth->ktr_len = sizeof(struct ktr_sysret);
97
98	ktrwrite(vp, kth);
99	FREE(kth, M_TEMP);
100	}
101
102	ktrnamei(vp, path)
103	struct vnode *vp;
104	char *path;
105	{
106	struct ktr_header *kth = ktrgetheader(KTR_NAMEI);
107
108	kth->ktr_len = strlen(path);
109	kth->ktr_buf = path;
110
111	ktrwrite(vp, kth);
112	FREE(kth, M_TEMP);
113	}
114
115	ktrgenio(vp, fd, rw, iov, len, error)
116	struct vnode *vp;
117	int fd;
118	enum uio_rw rw;
119	register struct iovec *iov;
120	{
121	struct ktr_header *kth = ktrgetheader(KTR_GENIO);
122	register struct ktr_genio *ktp;
123	register caddr_t cp;
124	register int resid = len, cnt;
125
126	if (error)
127	return;
128	MALLOC(ktp, struct ktr_genio *, sizeof(struct ktr_genio) + len,
129	M_TEMP, M_WAITOK);
130	ktp->ktr_fd = fd;
131	ktp->ktr_rw = rw;
132	cp = (caddr_t)((char *)ktp + sizeof (struct ktr_genio));
133	while (resid > 0) {
134	if ((cnt = iov->iov_len) > resid)
135	cnt = resid;
136	if (copyin(iov->iov_base, cp, (unsigned)cnt))
137	goto done;
138	cp += cnt;
139	resid -= cnt;
140	iov++;
141	}
142	kth->ktr_buf = (caddr_t)ktp;
143	kth->ktr_len = sizeof (struct ktr_genio) + len;
144
145	ktrwrite(vp, kth);
146	done:
147	FREE(kth, M_TEMP);
148	FREE(ktp, M_TEMP);
149	}
150
151	ktrpsig(vp, sig, action, mask, code)
152	struct vnode *vp;
153	sig_t action;
154	{
155	struct ktr_header *kth = ktrgetheader(KTR_PSIG);
156	struct ktr_psig kp;
157
158	kp.signo = (char)sig;
159	kp.action = action;
160	kp.mask = mask;
161	kp.code = code;
162	kth->ktr_buf = (caddr_t)&kp;
163	kth->ktr_len = sizeof (struct ktr_psig);
164
165	ktrwrite(vp, kth);
166	FREE(kth, M_TEMP);
167	}
168
169	/* Interface and common routines */
170
171	/*
172	* ktrace system call
173	*/
3c7eb27c DG	174
	175	struct ktrace_args {
	176	char *fname;
	177	int ops;
	178	int facs;
	179	int pid;
	180	};
	181
15637ed4 RG	182	/* ARGSUSED */
	183	ktrace(curp, uap, retval)
	184	struct proc *curp;
3c7eb27c	185	register struct ktrace_args *uap;
15637ed4 RG	186	int *retval;
	187	{
	188	register struct vnode *vp = NULL;
	189	register struct proc *p;
	190	struct pgrp *pg;
	191	int facs = uap->facs & ~KTRFAC_ROOT;
	192	int ops = KTROP(uap->ops);
	193	int descend = uap->ops & KTRFLAG_DESCEND;
	194	int ret = 0;
	195	int error = 0;
	196	struct nameidata nd;
	197
	198	if (ops != KTROP_CLEAR) {
	199	/*
	200	* an operation which requires a file argument.
	201	*/
	202	nd.ni_segflg = UIO_USERSPACE;
	203	nd.ni_dirp = uap->fname;
	204	if (error = vn_open(&nd, curp, FREAD\|FWRITE, 0))
	205	return (error);
	206	vp = nd.ni_vp;
	207	VOP_UNLOCK(vp);
	208	if (vp->v_type != VREG) {
	209	(void) vn_close(vp, FREAD\|FWRITE, curp->p_ucred, curp);
	210	return (EACCES);
	211	}
	212	}
	213	/*
	214	* Clear all uses of the tracefile
	215	*/
	216	if (ops == KTROP_CLEARFILE) {
	217	for (p = allproc; p != NULL; p = p->p_nxt) {
	218	if (p->p_tracep == vp) {
	219	if (ktrcanset(curp, p)) {
	220	p->p_tracep = NULL;
	221	p->p_traceflag = 0;
	222	(void) vn_close(vp, FREAD\|FWRITE,
	223	p->p_ucred, p);
	224	} else
	225	error = EPERM;
	226	}
	227	}
	228	goto done;
	229	}
	230	/*
	231	* need something to (un)trace (XXX - why is this here?)
	232	*/
	233	if (!facs) {
	234	error = EINVAL;
	235	goto done;
	236	}
	237	/*
	238	* do it
	239	*/
	240	if (uap->pid < 0) {
	241	/*
	242	* by process group
	243	*/
	244	pg = pgfind(-uap->pid);
	245	if (pg == NULL) {
	246	error = ESRCH;
	247	goto done;
	248	}
	249	for (p = pg->pg_mem; p != NULL; p = p->p_pgrpnxt)
250	if (descend)
251	ret \|= ktrsetchildren(curp, p, ops, facs, vp);
252	else
253	ret \|= ktrops(curp, p, ops, facs, vp);
254
255	} else {
256	/*
257	* by pid
258	*/
259	p = pfind(uap->pid);
260	if (p == NULL) {
261	error = ESRCH;
262	goto done;
263	}
264	if (descend)
265	ret \|= ktrsetchildren(curp, p, ops, facs, vp);
266	else
267	ret \|= ktrops(curp, p, ops, facs, vp);
268	}
269	if (!ret)
270	error = EPERM;
271	done:
272	if (vp != NULL)
273	(void) vn_close(vp, FWRITE, curp->p_ucred, curp);
274	return (error);
275	}
276
277	ktrops(curp, p, ops, facs, vp)
278	struct proc curp, p;
279	struct vnode *vp;
280	{
281
282	if (!ktrcanset(curp, p))
283	return (0);
284	if (ops == KTROP_SET) {
285	if (p->p_tracep != vp) {
286	/*
287	* if trace file already in use, relinquish
288	*/
289	if (p->p_tracep != NULL)
290	vrele(p->p_tracep);
291	VREF(vp);
292	p->p_tracep = vp;
293	}
294	p->p_traceflag \|= facs;
295	if (curp->p_ucred->cr_uid == 0)
296	p->p_traceflag \|= KTRFAC_ROOT;
297	} else {
298	/* KTROP_CLEAR */
299	if (((p->p_traceflag &= ~facs) & KTRFAC_MASK) == 0) {
300	/* no more tracing */
301	p->p_traceflag = 0;
302	if (p->p_tracep != NULL) {
303	vrele(p->p_tracep);
304	p->p_tracep = NULL;
305	}
306	}
307	}
308
309	return (1);
310	}
311
312	ktrsetchildren(curp, top, ops, facs, vp)
313	struct proc curp, top;
314	struct vnode *vp;
315	{
316	register struct proc *p;
317	register int ret = 0;
318
319	p = top;
320	for (;;) {
321	ret \|= ktrops(curp, p, ops, facs, vp);
322	/*
323	* If this process has children, descend to them next,
324	* otherwise do any siblings, and if done with this level,
325	* follow back up the tree (but not past top).
326	*/
327	if (p->p_cptr)
328	p = p->p_cptr;
329	else if (p == top)
330	return (ret);
331	else if (p->p_osptr)
332	p = p->p_osptr;
333	else for (;;) {
334	p = p->p_pptr;
335	if (p == top)
336	return (ret);
337	if (p->p_osptr) {
338	p = p->p_osptr;
339	break;
340	}
341	}
342	}
343	/NOTREACHED/
344	}
345
346	ktrwrite(vp, kth)
347	struct vnode *vp;
348	register struct ktr_header *kth;
349	{
350	struct uio auio;
351	struct iovec aiov[2];
352	register struct proc p = curproc; / XXX */
353	int error;
354
355	if (vp == NULL)
356	return;
357	auio.uio_iov = &aiov[0];
358	auio.uio_offset = 0;
359	auio.uio_segflg = UIO_SYSSPACE;
360	auio.uio_rw = UIO_WRITE;
361	aiov[0].iov_base = (caddr_t)kth;
362	aiov[0].iov_len = sizeof(struct ktr_header);
363	auio.uio_resid = sizeof(struct ktr_header);
364	auio.uio_iovcnt = 1;
365	auio.uio_procp = (struct proc *)0;
366	if (kth->ktr_len > 0) {
367	auio.uio_iovcnt++;
368	aiov[1].iov_base = kth->ktr_buf;
369	aiov[1].iov_len = kth->ktr_len;
370	auio.uio_resid += kth->ktr_len;
371	}
372	VOP_LOCK(vp);
373	error = VOP_WRITE(vp, &auio, IO_UNIT\|IO_APPEND, p->p_ucred);
374	VOP_UNLOCK(vp);
375	if (!error)
376	return;
377	/*
378	* If error encountered, give up tracing on this vnode.
379	*/
380	log(LOG_NOTICE, "ktrace write failed, errno %d, tracing stopped\n",
381	error);
382	for (p = allproc; p != NULL; p = p->p_nxt) {
383	if (p->p_tracep == vp) {
384	p->p_tracep = NULL;
385	p->p_traceflag = 0;
386	vrele(vp);
387	}
388	}
389	}
390
391	/*
392	* Return true if caller has permission to set the ktracing state
393	* of target. Essentially, the target can't possess any
394	* more permissions than the caller. KTRFAC_ROOT signifies that
395	* root previously set the tracing status on the target process, and
396	* so, only root may further change it.
397	*
398	* TODO: check groups. use caller effective gid.
399	*/
400	ktrcanset(callp, targetp)
401	struct proc callp, targetp;
402	{
403	register struct pcred *caller = callp->p_cred;
404	register struct pcred *target = targetp->p_cred;
405
406	if ((caller->pc_ucred->cr_uid == target->p_ruid &&
407	target->p_ruid == target->p_svuid &&
408	caller->p_rgid == target->p_rgid && /* XXX */
409	target->p_rgid == target->p_svgid &&
410	(targetp->p_traceflag & KTRFAC_ROOT) == 0) \|\|
411	caller->pc_ucred->cr_uid == 0)
412	return (1);
413
414	return (0);
415	}
416
417	#endif