Home | History | Annotate | Line # | Download | only in kern
kern_ktrace.c revision 1.4 
      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  *	from: @(#)kern_ktrace.c	7.15 (Berkeley) 6/21/91
     34  *	$Id: kern_ktrace.c,v 1.4 1993/06/27 06:01:37 andrew Exp $
     35  */
     36 
     37 #include "param.h"
     38 #include "systm.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 void ktrwrite __P((struct vnode *vp, struct ktr_header *kth));
     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 = ktrgetheader(KTR_SYSCALL);
     71 	struct	ktr_syscall *ktp;
     72 	register len = sizeof(struct ktr_syscall) + (narg * sizeof(int));
     73 	int 	*argp, i;
     74 
     75 	MALLOC(ktp, struct ktr_syscall *, len, M_TEMP, M_WAITOK);
     76 	ktp->ktr_code = code;
     77 	ktp->ktr_narg = narg;
     78 	argp = (int *)((char *)ktp + sizeof(struct ktr_syscall));
     79 	for (i = 0; i < narg; i++)
     80 		*argp++ = args[i];
     81 	kth->ktr_buf = (caddr_t)ktp;
     82 	kth->ktr_len = len;
     83 	ktrwrite(vp, kth);
     84 	FREE(ktp, M_TEMP);
     85 	FREE(kth, M_TEMP);
     86 }
     87 
     88 void
     89 ktrsysret(vp, code, error, retval)
     90 	struct vnode *vp;
     91 	int code, error, retval;
     92 {
     93 	struct ktr_header *kth = ktrgetheader(KTR_SYSRET);
     94 	struct ktr_sysret ktp;
     95 
     96 	ktp.ktr_code = code;
     97 	ktp.ktr_error = error;
     98 	ktp.ktr_retval = retval;		/* what about val2 ? */
     99 
    100 	kth->ktr_buf = (caddr_t)&ktp;
    101 	kth->ktr_len = sizeof(struct ktr_sysret);
    102 
    103 	ktrwrite(vp, kth);
    104 	FREE(kth, M_TEMP);
    105 }
    106 
    107 void
    108 ktrnamei(vp, path)
    109 	struct vnode *vp;
    110 	char *path;
    111 {
    112 	struct ktr_header *kth = ktrgetheader(KTR_NAMEI);
    113 
    114 	kth->ktr_len = strlen(path);
    115 	kth->ktr_buf = path;
    116 
    117 	ktrwrite(vp, kth);
    118 	FREE(kth, M_TEMP);
    119 }
    120 
    121 void
    122 ktrgenio(vp, fd, rw, iov, len, error)
    123 	struct vnode *vp;
    124 	int fd;
    125 	enum uio_rw rw;
    126 	register struct iovec *iov;
    127 	int len, error;
    128 {
    129 	struct ktr_header *kth = ktrgetheader(KTR_GENIO);
    130 	register struct ktr_genio *ktp;
    131 	register caddr_t cp;
    132 	register int resid = len, cnt;
    133 
    134 	if (error)
    135 		return;
    136 	MALLOC(ktp, struct ktr_genio *, sizeof(struct ktr_genio) + len,
    137 		M_TEMP, M_WAITOK);
    138 	ktp->ktr_fd = fd;
    139 	ktp->ktr_rw = rw;
    140 	cp = (caddr_t)((char *)ktp + sizeof (struct ktr_genio));
    141 	while (resid > 0) {
    142 		if ((cnt = iov->iov_len) > resid)
    143 			cnt = resid;
    144 		if (copyin(iov->iov_base, cp, (unsigned)cnt))
    145 			goto done;
    146 		cp += cnt;
    147 		resid -= cnt;
    148 		iov++;
    149 	}
    150 	kth->ktr_buf = (caddr_t)ktp;
    151 	kth->ktr_len = sizeof (struct ktr_genio) + len;
    152 
    153 	ktrwrite(vp, kth);
    154 done:
    155 	FREE(kth, M_TEMP);
    156 	FREE(ktp, M_TEMP);
    157 }
    158 
    159 void
    160 ktrpsig(vp, sig, action, mask, code)
    161 	struct	vnode *vp;
    162 	sig_t	action;
    163 	int sig, mask, code;
    164 {
    165 	struct ktr_header *kth = ktrgetheader(KTR_PSIG);
    166 	struct ktr_psig	kp;
    167 
    168 	kp.signo = (char)sig;
    169 	kp.action = action;
    170 	kp.mask = mask;
    171 	kp.code = code;
    172 	kth->ktr_buf = (caddr_t)&kp;
    173 	kth->ktr_len = sizeof (struct ktr_psig);
    174 
    175 	ktrwrite(vp, kth);
    176 	FREE(kth, M_TEMP);
    177 }
    178 
    179 /* Interface and common routines */
    180 
    181 /*
    182  * ktrace system call
    183  */
    184 /* ARGSUSED */
    185 int
    186 ktrace(curp, uap, retval)
    187 	struct proc *curp;
    188 	register struct args {
    189 		char	*fname;
    190 		int	ops;
    191 		int	facs;
    192 		int	pid;
    193 	} *uap;
    194 	int *retval;
    195 {
    196 	register struct vnode *vp = NULL;
    197 	register struct proc *p;
    198 	struct pgrp *pg;
    199 	int facs = uap->facs & ~KTRFAC_ROOT;
    200 	int ops = KTROP(uap->ops);
    201 	int descend = uap->ops & KTRFLAG_DESCEND;
    202 	int ret = 0;
    203 	int error = 0;
    204 	struct nameidata nd;
    205 
    206 	if (ops != KTROP_CLEAR) {
    207 		/*
    208 		 * an operation which requires a file argument.
    209 		 */
    210 		nd.ni_segflg = UIO_USERSPACE;
    211 		nd.ni_dirp = uap->fname;
    212 		if (error = vn_open(&nd, curp, FREAD|FWRITE, 0))
    213 			return (error);
    214 		vp = nd.ni_vp;
    215 		VOP_UNLOCK(vp);
    216 		if (vp->v_type != VREG) {
    217 			(void) vn_close(vp, FREAD|FWRITE, curp->p_ucred, curp);
    218 			return (EACCES);
    219 		}
    220 	}
    221 	/*
    222 	 * Clear all uses of the tracefile
    223 	 */
    224 	if (ops == KTROP_CLEARFILE) {
    225 		for (p = allproc; p != NULL; p = p->p_nxt) {
    226 			if (p->p_tracep == vp) {
    227 				if (ktrcanset(curp, p)) {
    228 					p->p_tracep = NULL;
    229 					p->p_traceflag = 0;
    230 					(void) vn_close(vp, FREAD|FWRITE,
    231 						p->p_ucred, p);
    232 				} else
    233 					error = EPERM;
    234 			}
    235 		}
    236 		goto done;
    237 	}
    238 	/*
    239 	 * need something to (un)trace (XXX - why is this here?)
    240 	 */
    241 	if (!facs) {
    242 		error = EINVAL;
    243 		goto done;
    244 	}
    245 	/*
    246 	 * do it
    247 	 */
    248 	if (uap->pid < 0) {
    249 		/*
    250 		 * by process group
    251 		 */
    252 		pg = pgfind(-uap->pid);
    253 		if (pg == NULL) {
    254 			error = ESRCH;
    255 			goto done;
    256 		}
    257 		for (p = pg->pg_mem; p != NULL; p = p->p_pgrpnxt)
    258 			if (descend)
    259 				ret |= ktrsetchildren(curp, p, ops, facs, vp);
    260 			else
    261 				ret |= ktrops(curp, p, ops, facs, vp);
    262 
    263 	} else {
    264 		/*
    265 		 * by pid
    266 		 */
    267 		p = pfind(uap->pid);
    268 		if (p == NULL) {
    269 			error = ESRCH;
    270 			goto done;
    271 		}
    272 		if (descend)
    273 			ret |= ktrsetchildren(curp, p, ops, facs, vp);
    274 		else
    275 			ret |= ktrops(curp, p, ops, facs, vp);
    276 	}
    277 	if (!ret)
    278 		error = EPERM;
    279 done:
    280 	if (vp != NULL)
    281 		(void) vn_close(vp, FWRITE, curp->p_ucred, curp);
    282 	return (error);
    283 }
    284 
    285 int
    286 ktrops(curp, p, ops, facs, vp)
    287 	struct proc *curp, *p;
    288 	int ops, facs;
    289 	struct vnode *vp;
    290 {
    291 
    292 	if (!ktrcanset(curp, p))
    293 		return (0);
    294 	if (ops == KTROP_SET) {
    295 		if (p->p_tracep != vp) {
    296 			/*
    297 			 * if trace file already in use, relinquish
    298 			 */
    299 			if (p->p_tracep != NULL)
    300 				vrele(p->p_tracep);
    301 			VREF(vp);
    302 			p->p_tracep = vp;
    303 		}
    304 		p->p_traceflag |= facs;
    305 		if (curp->p_ucred->cr_uid == 0)
    306 			p->p_traceflag |= KTRFAC_ROOT;
    307 	} else {
    308 		/* KTROP_CLEAR */
    309 		if (((p->p_traceflag &= ~facs) & KTRFAC_MASK) == 0) {
    310 			/* no more tracing */
    311 			p->p_traceflag = 0;
    312 			if (p->p_tracep != NULL) {
    313 				vrele(p->p_tracep);
    314 				p->p_tracep = NULL;
    315 			}
    316 		}
    317 	}
    318 
    319 	return (1);
    320 }
    321 
    322 int
    323 ktrsetchildren(curp, top, ops, facs, vp)
    324 	struct proc *curp, *top;
    325 	int ops, facs;
    326 	struct vnode *vp;
    327 {
    328 	register struct proc *p;
    329 	register int ret = 0;
    330 
    331 	p = top;
    332 	for (;;) {
    333 		ret |= ktrops(curp, p, ops, facs, vp);
    334 		/*
    335 		 * If this process has children, descend to them next,
    336 		 * otherwise do any siblings, and if done with this level,
    337 		 * follow back up the tree (but not past top).
    338 		 */
    339 		if (p->p_cptr)
    340 			p = p->p_cptr;
    341 		else if (p == top)
    342 			return (ret);
    343 		else if (p->p_osptr)
    344 			p = p->p_osptr;
    345 		else for (;;) {
    346 			p = p->p_pptr;
    347 			if (p == top)
    348 				return (ret);
    349 			if (p->p_osptr) {
    350 				p = p->p_osptr;
    351 				break;
    352 			}
    353 		}
    354 	}
    355 	/*NOTREACHED*/
    356 }
    357 
    358 void
    359 ktrwrite(vp, kth)
    360 	struct vnode *vp;
    361 	register struct ktr_header *kth;
    362 {
    363 	struct uio auio;
    364 	struct iovec aiov[2];
    365 	register struct proc *p = curproc;	/* XXX */
    366 	int error;
    367 
    368 	if (vp == NULL)
    369 		return;
    370 	auio.uio_iov = &aiov[0];
    371 	auio.uio_offset = 0;
    372 	auio.uio_segflg = UIO_SYSSPACE;
    373 	auio.uio_rw = UIO_WRITE;
    374 	aiov[0].iov_base = (caddr_t)kth;
    375 	aiov[0].iov_len = sizeof(struct ktr_header);
    376 	auio.uio_resid = sizeof(struct ktr_header);
    377 	auio.uio_iovcnt = 1;
    378 	auio.uio_procp = (struct proc *)0;
    379 	if (kth->ktr_len > 0) {
    380 		auio.uio_iovcnt++;
    381 		aiov[1].iov_base = kth->ktr_buf;
    382 		aiov[1].iov_len = kth->ktr_len;
    383 		auio.uio_resid += kth->ktr_len;
    384 	}
    385 	VOP_LOCK(vp);
    386 	error = VOP_WRITE(vp, &auio, IO_UNIT|IO_APPEND, p->p_ucred);
    387 	VOP_UNLOCK(vp);
    388 	if (!error)
    389 		return;
    390 	/*
    391 	 * If error encountered, give up tracing on this vnode.
    392 	 */
    393 	log(LOG_NOTICE, "ktrace write failed, errno %d, tracing stopped\n",
    394 	    error);
    395 	for (p = allproc; p != NULL; p = p->p_nxt) {
    396 		if (p->p_tracep == vp) {
    397 			p->p_tracep = NULL;
    398 			p->p_traceflag = 0;
    399 			vrele(vp);
    400 		}
    401 	}
    402 }
    403 
    404 /*
    405  * Return true if caller has permission to set the ktracing state
    406  * of target.  Essentially, the target can't possess any
    407  * more permissions than the caller.  KTRFAC_ROOT signifies that
    408  * root previously set the tracing status on the target process, and
    409  * so, only root may further change it.
    410  *
    411  * TODO: check groups.  use caller effective gid.
    412  */
    413 int
    414 ktrcanset(callp, targetp)
    415 	struct proc *callp, *targetp;
    416 {
    417 	register struct pcred *caller = callp->p_cred;
    418 	register struct pcred *target = targetp->p_cred;
    419 
    420 	if ((caller->pc_ucred->cr_uid == target->p_ruid &&
    421 	     target->p_ruid == target->p_svuid &&
    422 	     caller->p_rgid == target->p_rgid &&	/* XXX */
    423 	     target->p_rgid == target->p_svgid &&
    424 	     (targetp->p_traceflag & KTRFAC_ROOT) == 0) ||
    425 	     caller->pc_ucred->cr_uid == 0)
    426 		return (1);
    427 
    428 	return (0);
    429 }
    430