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kern_ktrace.c revision 1.3 
      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 1.3 1993/05/20 02:54:26 cgd Exp $
     35  */
     36 
     37 #include "param.h"
     38 #include "proc.h"
     39 #include "file.h"
     40 #include "namei.h"
     41 #include "vnode.h"
     42 #include "ktrace.h"
     43 #include "malloc.h"
     44 #include "syslog.h"
     45 
     46 struct ktr_header *
     47 ktrgetheader(type)
     48 {
     49 	register struct ktr_header *kth;
     50 	struct proc *p = curproc;	/* XXX */
     51 
     52 	MALLOC(kth, struct ktr_header *, sizeof (struct ktr_header),
     53 		M_TEMP, M_WAITOK);
     54 	kth->ktr_type = type;
     55 	microtime(&kth->ktr_time);
     56 	kth->ktr_pid = p->p_pid;
     57 	bcopy(p->p_comm, kth->ktr_comm, MAXCOMLEN);
     58 	return (kth);
     59 }
     60 
     61 ktrsyscall(vp, code, narg, args)
     62 	struct vnode *vp;
     63 	int code, narg, args[];
     64 {
     65 	struct	ktr_header *kth = ktrgetheader(KTR_SYSCALL);
     66 	struct	ktr_syscall *ktp;
     67 	register len = sizeof(struct ktr_syscall) + (narg * sizeof(int));
     68 	int 	*argp, i;
     69 
     70 	MALLOC(ktp, struct ktr_syscall *, len, M_TEMP, M_WAITOK);
     71 	ktp->ktr_code = code;
     72 	ktp->ktr_narg = narg;
     73 	argp = (int *)((char *)ktp + sizeof(struct ktr_syscall));
     74 	for (i = 0; i < narg; i++)
     75 		*argp++ = args[i];
     76 	kth->ktr_buf = (caddr_t)ktp;
     77 	kth->ktr_len = len;
     78 	ktrwrite(vp, kth);
     79 	FREE(ktp, M_TEMP);
     80 	FREE(kth, M_TEMP);
     81 }
     82 
     83 ktrsysret(vp, code, error, retval)
     84 	struct vnode *vp;
     85 	int code, error, retval;
     86 {
     87 	struct ktr_header *kth = ktrgetheader(KTR_SYSRET);
     88 	struct ktr_sysret ktp;
     89 
     90 	ktp.ktr_code = code;
     91 	ktp.ktr_error = error;
     92 	ktp.ktr_retval = retval;		/* what about val2 ? */
     93 
     94 	kth->ktr_buf = (caddr_t)&ktp;
     95 	kth->ktr_len = sizeof(struct ktr_sysret);
     96 
     97 	ktrwrite(vp, kth);
     98 	FREE(kth, M_TEMP);
     99 }
    100 
    101 ktrnamei(vp, path)
    102 	struct vnode *vp;
    103 	char *path;
    104 {
    105 	struct ktr_header *kth = ktrgetheader(KTR_NAMEI);
    106 
    107 	kth->ktr_len = strlen(path);
    108 	kth->ktr_buf = path;
    109 
    110 	ktrwrite(vp, kth);
    111 	FREE(kth, M_TEMP);
    112 }
    113 
    114 ktrgenio(vp, fd, rw, iov, len, error)
    115 	struct vnode *vp;
    116 	int fd;
    117 	enum uio_rw rw;
    118 	register struct iovec *iov;
    119 {
    120 	struct ktr_header *kth = ktrgetheader(KTR_GENIO);
    121 	register struct ktr_genio *ktp;
    122 	register caddr_t cp;
    123 	register int resid = len, cnt;
    124 
    125 	if (error)
    126 		return;
    127 	MALLOC(ktp, struct ktr_genio *, sizeof(struct ktr_genio) + len,
    128 		M_TEMP, M_WAITOK);
    129 	ktp->ktr_fd = fd;
    130 	ktp->ktr_rw = rw;
    131 	cp = (caddr_t)((char *)ktp + sizeof (struct ktr_genio));
    132 	while (resid > 0) {
    133 		if ((cnt = iov->iov_len) > resid)
    134 			cnt = resid;
    135 		if (copyin(iov->iov_base, cp, (unsigned)cnt))
    136 			goto done;
    137 		cp += cnt;
    138 		resid -= cnt;
    139 		iov++;
    140 	}
    141 	kth->ktr_buf = (caddr_t)ktp;
    142 	kth->ktr_len = sizeof (struct ktr_genio) + len;
    143 
    144 	ktrwrite(vp, kth);
    145 done:
    146 	FREE(kth, M_TEMP);
    147 	FREE(ktp, M_TEMP);
    148 }
    149 
    150 ktrpsig(vp, sig, action, mask, code)
    151 	struct	vnode *vp;
    152 	sig_t	action;
    153 {
    154 	struct ktr_header *kth = ktrgetheader(KTR_PSIG);
    155 	struct ktr_psig	kp;
    156 
    157 	kp.signo = (char)sig;
    158 	kp.action = action;
    159 	kp.mask = mask;
    160 	kp.code = code;
    161 	kth->ktr_buf = (caddr_t)&kp;
    162 	kth->ktr_len = sizeof (struct ktr_psig);
    163 
    164 	ktrwrite(vp, kth);
    165 	FREE(kth, M_TEMP);
    166 }
    167 
    168 /* Interface and common routines */
    169 
    170 /*
    171  * ktrace system call
    172  */
    173 /* ARGSUSED */
    174 ktrace(curp, uap, retval)
    175 	struct proc *curp;
    176 	register struct args {
    177 		char	*fname;
    178 		int	ops;
    179 		int	facs;
    180 		int	pid;
    181 	} *uap;
    182 	int *retval;
    183 {
    184 	register struct vnode *vp = NULL;
    185 	register struct proc *p;
    186 	struct pgrp *pg;
    187 	int facs = uap->facs & ~KTRFAC_ROOT;
    188 	int ops = KTROP(uap->ops);
    189 	int descend = uap->ops & KTRFLAG_DESCEND;
    190 	int ret = 0;
    191 	int error = 0;
    192 	struct nameidata nd;
    193 
    194 	if (ops != KTROP_CLEAR) {
    195 		/*
    196 		 * an operation which requires a file argument.
    197 		 */
    198 		nd.ni_segflg = UIO_USERSPACE;
    199 		nd.ni_dirp = uap->fname;
    200 		if (error = vn_open(&nd, curp, FREAD|FWRITE, 0))
    201 			return (error);
    202 		vp = nd.ni_vp;
    203 		VOP_UNLOCK(vp);
    204 		if (vp->v_type != VREG) {
    205 			(void) vn_close(vp, FREAD|FWRITE, curp->p_ucred, curp);
    206 			return (EACCES);
    207 		}
    208 	}
    209 	/*
    210 	 * Clear all uses of the tracefile
    211 	 */
    212 	if (ops == KTROP_CLEARFILE) {
    213 		for (p = allproc; p != NULL; p = p->p_nxt) {
    214 			if (p->p_tracep == vp) {
    215 				if (ktrcanset(curp, p)) {
    216 					p->p_tracep = NULL;
    217 					p->p_traceflag = 0;
    218 					(void) vn_close(vp, FREAD|FWRITE,
    219 						p->p_ucred, p);
    220 				} else
    221 					error = EPERM;
    222 			}
    223 		}
    224 		goto done;
    225 	}
    226 	/*
    227 	 * need something to (un)trace (XXX - why is this here?)
    228 	 */
    229 	if (!facs) {
    230 		error = EINVAL;
    231 		goto done;
    232 	}
    233 	/*
    234 	 * do it
    235 	 */
    236 	if (uap->pid < 0) {
    237 		/*
    238 		 * by process group
    239 		 */
    240 		pg = pgfind(-uap->pid);
    241 		if (pg == NULL) {
    242 			error = ESRCH;
    243 			goto done;
    244 		}
    245 		for (p = pg->pg_mem; p != NULL; p = p->p_pgrpnxt)
    246 			if (descend)
    247 				ret |= ktrsetchildren(curp, p, ops, facs, vp);
    248 			else
    249 				ret |= ktrops(curp, p, ops, facs, vp);
    250 
    251 	} else {
    252 		/*
    253 		 * by pid
    254 		 */
    255 		p = pfind(uap->pid);
    256 		if (p == NULL) {
    257 			error = ESRCH;
    258 			goto done;
    259 		}
    260 		if (descend)
    261 			ret |= ktrsetchildren(curp, p, ops, facs, vp);
    262 		else
    263 			ret |= ktrops(curp, p, ops, facs, vp);
    264 	}
    265 	if (!ret)
    266 		error = EPERM;
    267 done:
    268 	if (vp != NULL)
    269 		(void) vn_close(vp, FWRITE, curp->p_ucred, curp);
    270 	return (error);
    271 }
    272 
    273 ktrops(curp, p, ops, facs, vp)
    274 	struct proc *curp, *p;
    275 	struct vnode *vp;
    276 {
    277 
    278 	if (!ktrcanset(curp, p))
    279 		return (0);
    280 	if (ops == KTROP_SET) {
    281 		if (p->p_tracep != vp) {
    282 			/*
    283 			 * if trace file already in use, relinquish
    284 			 */
    285 			if (p->p_tracep != NULL)
    286 				vrele(p->p_tracep);
    287 			VREF(vp);
    288 			p->p_tracep = vp;
    289 		}
    290 		p->p_traceflag |= facs;
    291 		if (curp->p_ucred->cr_uid == 0)
    292 			p->p_traceflag |= KTRFAC_ROOT;
    293 	} else {
    294 		/* KTROP_CLEAR */
    295 		if (((p->p_traceflag &= ~facs) & KTRFAC_MASK) == 0) {
    296 			/* no more tracing */
    297 			p->p_traceflag = 0;
    298 			if (p->p_tracep != NULL) {
    299 				vrele(p->p_tracep);
    300 				p->p_tracep = NULL;
    301 			}
    302 		}
    303 	}
    304 
    305 	return (1);
    306 }
    307 
    308 ktrsetchildren(curp, top, ops, facs, vp)
    309 	struct proc *curp, *top;
    310 	struct vnode *vp;
    311 {
    312 	register struct proc *p;
    313 	register int ret = 0;
    314 
    315 	p = top;
    316 	for (;;) {
    317 		ret |= ktrops(curp, p, ops, facs, vp);
    318 		/*
    319 		 * If this process has children, descend to them next,
    320 		 * otherwise do any siblings, and if done with this level,
    321 		 * follow back up the tree (but not past top).
    322 		 */
    323 		if (p->p_cptr)
    324 			p = p->p_cptr;
    325 		else if (p == top)
    326 			return (ret);
    327 		else if (p->p_osptr)
    328 			p = p->p_osptr;
    329 		else for (;;) {
    330 			p = p->p_pptr;
    331 			if (p == top)
    332 				return (ret);
    333 			if (p->p_osptr) {
    334 				p = p->p_osptr;
    335 				break;
    336 			}
    337 		}
    338 	}
    339 	/*NOTREACHED*/
    340 }
    341 
    342 ktrwrite(vp, kth)
    343 	struct vnode *vp;
    344 	register struct ktr_header *kth;
    345 {
    346 	struct uio auio;
    347 	struct iovec aiov[2];
    348 	register struct proc *p = curproc;	/* XXX */
    349 	int error;
    350 
    351 	if (vp == NULL)
    352 		return;
    353 	auio.uio_iov = &aiov[0];
    354 	auio.uio_offset = 0;
    355 	auio.uio_segflg = UIO_SYSSPACE;
    356 	auio.uio_rw = UIO_WRITE;
    357 	aiov[0].iov_base = (caddr_t)kth;
    358 	aiov[0].iov_len = sizeof(struct ktr_header);
    359 	auio.uio_resid = sizeof(struct ktr_header);
    360 	auio.uio_iovcnt = 1;
    361 	auio.uio_procp = (struct proc *)0;
    362 	if (kth->ktr_len > 0) {
    363 		auio.uio_iovcnt++;
    364 		aiov[1].iov_base = kth->ktr_buf;
    365 		aiov[1].iov_len = kth->ktr_len;
    366 		auio.uio_resid += kth->ktr_len;
    367 	}
    368 	VOP_LOCK(vp);
    369 	error = VOP_WRITE(vp, &auio, IO_UNIT|IO_APPEND, p->p_ucred);
    370 	VOP_UNLOCK(vp);
    371 	if (!error)
    372 		return;
    373 	/*
    374 	 * If error encountered, give up tracing on this vnode.
    375 	 */
    376 	log(LOG_NOTICE, "ktrace write failed, errno %d, tracing stopped\n",
    377 	    error);
    378 	for (p = allproc; p != NULL; p = p->p_nxt) {
    379 		if (p->p_tracep == vp) {
    380 			p->p_tracep = NULL;
    381 			p->p_traceflag = 0;
    382 			vrele(vp);
    383 		}
    384 	}
    385 }
    386 
    387 /*
    388  * Return true if caller has permission to set the ktracing state
    389  * of target.  Essentially, the target can't possess any
    390  * more permissions than the caller.  KTRFAC_ROOT signifies that
    391  * root previously set the tracing status on the target process, and
    392  * so, only root may further change it.
    393  *
    394  * TODO: check groups.  use caller effective gid.
    395  */
    396 ktrcanset(callp, targetp)
    397 	struct proc *callp, *targetp;
    398 {
    399 	register struct pcred *caller = callp->p_cred;
    400 	register struct pcred *target = targetp->p_cred;
    401 
    402 	if ((caller->pc_ucred->cr_uid == target->p_ruid &&
    403 	     target->p_ruid == target->p_svuid &&
    404 	     caller->p_rgid == target->p_rgid &&	/* XXX */
    405 	     target->p_rgid == target->p_svgid &&
    406 	     (targetp->p_traceflag & KTRFAC_ROOT) == 0) ||
    407 	     caller->pc_ucred->cr_uid == 0)
    408 		return (1);
    409 
    410 	return (0);
    411 }
    412